Question 1

A 64-year-old woman was found poorly responsive in her apartment and brought to the hospital via ambulance.  She has recently become more withdrawn and no longer participates in events at her local senior center during the past few weeks.  Her medical history includes severe degenerative arthritis of her hips and knees, type 2 diabetes mellitus, hyperlipidemia, and hypertension.  Her medications include aspirin, atenolol, lovastatin, metformin, and NSAIDs in unknown doses.  She has no known drug allergies.  She has no history of tobacco or alcohol use.
Examination shows that she is lethargic and complains of poor hearing.  She is only oriented to person.  Her temperature is 37.3°C (99.1°F), blood pressure is 130/76 mm Hg, pulse is 110/min, and respirations are 24/min.  Her pulse oximetry shows 94% on room air.  Her neck is supple.  Examinations of the heart and lungs show no abnormalities.  Abdominal examination reveals no tenderness.  She has 2+ pulses, with warm extremities.  There are no focal neurologic findings.
The patient's laboratory studies reveal:

Chest x-ray shows no abnormalities.
Which of the following interventions would be most beneficial for this patient?

Accepted Answer

This patient's clinical presentation is strongly suggestive of salicylate toxicity, with the classic clinical features summarized in the table below. Salicylate directly stimulates the central respiratory center to cause a respiratory alkalosis and also uncouples oxidative phosphorylation to cause an increased anion gap metabolic acidosis (due to increased lactate). 11ec193a_971f_e4b4_853d_554109d20c01_MD0002_00 Salicylate intoxication often results in decreased hearing, tinnitus, and a lower serum uric acid level (decreased tubular reabsorption of uric acid). Salicylate can also directly suppress synthesis of some vitamin K-dependent coagulation factors, resulting in mild elevation of the prothrombin time. Diagnosis is confirmed by an elevated plasma salicylate level. Treatment involves supportive care (i.e., oxygen). Patients should not be intubated, if possible, because aspirin acts on the respiratory center in the medulla and can cause a marked increase in minute ventilation. Alkalinization of the urine with intravenous bicarbonate traps the ionic form of salicylic acid in tubular fluid and enhances renal elimination. Note that alkalinization is NOT contraindicated, despite the presence of alkalemia from respiratory alkalosis. Hemodialysis is reserved for patients with altered mental status, pulmonary or cerebral edema, renal insufficiency, and salicylate level >100 mg/dL. (Choice A) N-acetylcysteine is a treatment for acetaminophen toxicity, which may present with abnormal mental status, elevated liver function tests, and increased prothrombin time. However, this patient's liver function tests are only mildly elevated and do not explain the remainder of the clinical scenario (i.e., poor hearing, low uric acid, and acid-base disturbance). N (Choice B) Pulmonary embolism typically presents with hypoxia, pleuritic chest pain, and respiratory alkalosis. This patient has respiratory alkalosis, but the elevated prothrombin time and altered mentation without hypoxia are less consistent with pulmonary embolism. (Choice C) While an acute neurologic event may cause altered mentation, a stroke is not consistent with this patient's laboratory values and clinical presentation. (Choice E) Sepsis can result in combined respiratory alkalosis and anion gap metabolic acidosis due to increased lactate. This patient has normal urinalysis and a negative chest x-ray; early sepsis could still be possible but is less likely. Educational objective: Combined respiratory alkalosis and increased anion gap metabolic acidosis suggest the presence of salicylate intoxication. Other clinical and laboratory features include decreased hearing, tinnitus, and very low serum uric acid. Treatment is supportive and involves alkalization of the urine with intravenous bicarbonate to promote renal excretion. Dialysis is reserved for more serious cases. __________ References: Unrecognized adult salicylate intoxication (http://www.ncbi.nlm.nih.gov/pubmed/999110)

Question 2

A 48-year-old man comes to the emergency department due to fever and cellulitis of the distal right lower extremity.  He was initially seen in a clinic 2 days earlier and treated with oral clindamycin, but he subsequently developed increasing erythema.  Medical history is notable for nondeforming rheumatoid arthritis treated with hydroxychloroquine and a similar episode of cellulitis 2 years ago that resolved with a course of cefazolin.  The patient is admitted to the hospital and treated with cefazolin and leg elevation.  His fever rapidly resolves and the area of erythema recedes.  However, 3 days after admission, serum creatinine increases from 1.2 to 1.9 mg/dL.
Urinalysis results are as follows:
 Urine stain for eosinophils is negative.
Which of the following is the most likely diagnosis in this patient?

Accepted Answer

11ec193a_9721_b977_853d_15f64b9b41e8_MD0002_00 This patient has acute kidney injury (AKI) with pyuria, hematuria, and granular casts on urinalysis. In the setting of antibiotic therapy for cellulitis, this most likely represents antibiotic-induced acute interstitial nephritis (AIN). Drugs are the most common cause of AIN, implicated in up to 75% of cases. Major classes include antibiotics, proton pump inhibitors, and nonsteroidal anti-inflammatory drugs. Onset is generally within weeks to months after primary exposure but develops more rapidly (days) after repeat exposure. Characteristic features of AIN include rash (15%), fever (27%), and eosinophilia (23%), although patients rarely have all 3 and may be asymptomatic. Urinalysis commonly shows pyuria, hematuria, and white blood cell casts with varying degrees of proteinuria but may also be normal. Granular casts are noted in a variety of kidney pathologies and are nondiagnostic. Urinary eosinophils can be seen in up to 40% of patients with AIN, but they are present in a variety of diseases (eg, prostatitis, renal atheroemboli); therefore, their presence is supportive but nondiagnostic. Renal biopsy can confirm the diagnosis but is not required if renal function improves after the culprit drug is stopped. (Choice B) Although infectious processes can result in acute immune complex glomerulonephritis, this is usually associated with significant proteinuria and red blood cell casts. (Choice C) Prerenal AKI can develop in the setting of an acute illness but would not typically be associated with cells and casts on urinalysis. (Choices D and E) Renal involvement is rarely seen in rheumatoid arthritis and generally occurs in advanced, joint-destructive disease. Manifestations can include renal vasculitis, glomerulonephritis, or membranous nephropathy. Renal vasculitis and glomerulonephritis present with red blood cell casts, and membranous nephropathy causes significant proteinuria; neither finding is seen in this patient. Educational objective: Acute kidney injury after implementation of a new drug (especially antibiotics) should raise suspicion for acute interstitial nephritis. Symptom onset is variable and generally occurs weeks to months after primary exposure; however, symptoms develop more rapidly (days) after second exposure. The presence of white blood cell casts, urine eosinophils, hematuria, and pyuria are suggestive but not required for diagnosis. __________ References: Drug-induced acute interstitial nephritis. (http://www.ncbi.nlm.nih.gov/pubmed/20517290) Acute interstitial nephritis. (http://www.ncbi.nlm.nih.gov/pubmed/20336051)

Question 3

A 48-year-old man is admitted to the hospital for recurrent, diffuse abdominal pain.  The pain has occurred intermittently for the past 8 months and is worse after eating.  Four months ago, the patient underwent emergency laparoscopic surgery with resection of necrotic gallbladder and omental tissue, but he continued to have symptoms.  In addition, the patient has experienced intermittent testicular pain and a 13.7-kg (30-lb) weight loss since the onset of symptoms.  Medical history is notable for chronic hepatitis B, exercise-induced asthma, acid reflux disease, and renal stones.  The patient has a 25-pack-year smoking history and drinks alcohol occasionally.  His medications include an albuterol inhaler and omeprazole as needed.
Temperature is 38 C (100.5 F), blood pressure is 180/100 mm Hg, pulse is 78/min, and respirations are 12/min.  On examination, the patient appears anxious and diaphoretic.  Cardiopulmonary examination is normal.  Abdominal palpation elicits diffuse tenderness without any rebound or guarding.  Bowel sounds are present.  No abdominal masses are palpable, and the stool is negative on guaiac testing.  The right testicle appears swollen and tender.  There are no skin rashes.
Laboratory results show normal serum chemistry, liver function studies, and complete blood count.  Other study results are as follows:
 Blood cultures, urinalysis, and urine culture are normal.  Chest x-ray and ECG are also normal.
Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_9727_10b6_853d_d9e63e9a93e1_MD0002_00 This patient has recurrent postprandial abdominal pain suggesting mesenteric ischemia, uncontrolled hypertension, systemic signs and symptoms (ie, fever, weight loss), and elevated inflammatory markers. In light of his negative antineutrophil cytoplasmic antibody (ANCA) test and history of hepatitis B, this presentation is consistent with polyarteritis nodosa (PAN). PAN is a multisystem, necrotizing vasculitis typically involving the mesenteric and renal vessels but sparing the lungs. It is characterized by immune-mediated, small- and medium-size arterial injury with lumenal narrowing, reduced blood flow, and thrombosis, leading to tissue infarction and aneurysm formation. In addition to abdominal (eg, mesenteric ischemia) and gallbladder involvement, this patient has evidence of orchitis (eg, testicular pain, swelling). PAN has been associated with hepatitis B, hepatitis C, and hairy cell leukemia, but the precise etiology is not well understood. There is no specific serologic test for PAN; however, a positive ANCA or antinuclear antibody test suggests an alternate vasculitic process. Tissue biopsy is generally needed for diagnosis. If there is no obvious site for biopsy, the diagnosis can be suggested by angiography showing renal, hepatic, or mesenteric microaneurysms. Treatment usually involves corticosteroids and cyclophosphamide. (Choice A) Essential mixed cryoglobulinemia is associated predominantly with hepatitis C and less commonly with hepatitis B. It usually presents with purpura, weakness, arthralgias, and renal disease. This patient's absence of skin rash makes this diagnosis less likely. (Choice B) Granulomatosis with polyangiitis is characterized by upper and lower airway inflammation and glomerulonephritis. ANCA is positive in >80% of cases. (Choice C) Henoch-Schönlein purpura is an IgA-mediated systemic vasculitis that is primarily seen in children but is less common in adults. Almost all patients have palpable purpura. (Choice D) Like PAN, microscopic polyangiitis causes vasculitis affecting small- and medium-sized arteries. However, glomerulonephritis is present in 80% of cases, pulmonary involvement (eg, hemoptysis) is common, gastrointestinal involvement is uncommon, and the majority of patients have a positive ANCA assay. Educational objective: Polyarteritis nodosa is a small- and medium-vessel vasculitis that presents with multiorgan manifestations (sparing the lungs). It is often associated with hepatitis B. Anti-neutrophil cytoplasmic antibody is negative. Tissue biopsy confirms the diagnosis. If there is no obvious site for biopsy, the diagnosis can be suggested by angiography showing renal, hepatic, or mesenteric microaneurysms. __________ References: Clinical features and outcomes in 348 patients with polyarteritis nodosa: a systematic retrospective study of patients diagnosed between 1963 and 2005 and entered into the French Vasculitis Study Group Database. (http://www.ncbi.nlm.nih.gov/pubmed/20112401) Polyarteritis nodosa. (http://www.ncbi.nlm.nih.gov/pubmed/25399938)

Question 4

A 25-year-old woman being treated for infective endocarditis is evaluated for new-onset renal dysfunction.  The patient has a 2-year history of injection drug use and presented 3 weeks ago with subjective fevers, pleuritic chest pain, and shortness of breath.  Chest CT imaging with contrast revealed peripheral nodular opacities consistent with septic emboli, and blood cultures were positive for Enterococcus faecalis.  Echocardiography showed tricuspid valve vegetations without valvular insufficiency or abnormal cardiac function.  The patient has been receiving intravenous ampicillin and ceftriaxone, and repeat blood cultures have been negative.  Yesterday, she was noted to have elevated serum creatinine on routine weekly laboratory studies.  The patient has no nausea, vomiting, flank pain, rash, dysuria, or chills.  She continues to void regularly with no changes in appearance or volume of her urine.
Temperature is 38.3 C (100.9 F), blood pressure is 122/64 mm Hg, pulse is 90/min, and respirations are 14/min.  Physical examination shows no jugular venous distension, and auscultation of the heart and lungs is normal.  There is no abdominal or costovertebral angle tenderness.  No rash or edema is present.
Repeat laboratory results are as follows:
 Which of the following is the most likely diagnosis in this patient?

Accepted Answer

11ec193a_9725_b122_853d_35966f77bd15_MD0002_00 This patient has acute renal failure 2 weeks after initiation of antibiotic therapy with concomitant fever, eosinophilia, and hematuria, pyuria, white blood cell (WBC) casts on urinalysis. This constellation of findings suggests acute interstitial nephritis (AIN), likely due to ampicillin. Up to 75% of cases of AIN are due to drugs, especially antibiotics (eg, penicillins, trimethoprim-sulfamethoxazole), nonsteroidal anti-inflammatory drugs, and proton pump inhibitors. Other causes include autoimmune disorders, malignancy, and certain infections (eg, Legionella). Onset is variable and generally occurs weeks to months after primary exposure; however, symptoms develop more rapidly (days) after second exposure. Clinical features of AIN resemble an allergic response and include fevers, rash, and eosinophilia, although all 3 symptoms occur in only 10% of cases and patients may be asymptomatic. Urinalysis classically shows hematuria, pyuria with white blood cell (WBC) casts, and variable proteinuria. Urinary eosinophils are supportive but are not sensitive or specific. Renal biopsy is diagnostic but is not required if symptoms resolve after drug withdrawal. (Choice A) Cholesterol embolization causes renal failure, sterile pyuria, and WBC casts but typically occurs following percutaneous endovascular procedures in older patients with significant atherosclerosis. This young woman is unlikely to have significant atherosclerosis and has not undergone an invasive procedure in >2 weeks. (Choices B and D) Contrast-induced nephropathy is a type of drug-induced acute tubular necrosis classically seen following CT studies. Renal failure typically occurs 24-48 hours after exposure, and urinalysis would be expected to show muddy brown casts, not WBC casts. (Choice E) Immune complex-mediated glomerulonephritis (eg, membranoproliferative, postinfectious) is characterized by acute renal failure with dysmorphic red blood cells and red blood cell casts, not WBC casts. In addition, postinfectious glomerulonephritis is more common after streptococcal or staphylococcal infections rather than enterococcal infections. Educational objective: Acute interstitial nephritis is characterized by acute renal failure with concurrent fever, rash, and eosinophilia, with sterile pyuria, hematuria, and white blood cell casts on urinalysis. Common causes include antibiotics, nonsteroidal anti-inflammatory drugs, and proton pump inhibitors. __________ References: Acute interstitial nephritis - a reappraisal and update. (http://www.ncbi.nlm.nih.gov/pubmed/25079860)

Question 5

A 47-year-old man is hospitalized due to worsening shortness of breath over the last 2 days. He complains of orthopnea requiring 2 pillows to sleep. The patient has a history of coronary artery disease and underwent coronary artery bypass grafting 2 years ago. He has been nonadherent with his medications. His temperature is 98.6° F (37° C), blood pressure is 157/90 mm Hg, pulse is 113/min, and respirations are 34/min. Pulse oximetry shows 88% on 100% O₂ non-rebreather face mask. He appears to be in respiratory distress and is using accessory muscles of respiration. Jugular venous pressure is estimated at 12 cm H₂O. Examination shows a third heart sound and bibasilar crackles. There is 1+ pitting peripheral edema bilaterally to the shins. The patient's chest-x ray is shown below. ECG shows sinus tachycardia with nonspecific T-wave changes. Which of the following best describes how noninvasive positive pressure would benefit this patient?

Accepted Answer

This patient has acute decompensated heart failure (ADHF), likely due to reduced left ventricular systolic function, as evidenced by cardiomegaly on imaging. The reduced cardiac output increases left ventricular filling pressures and left atrial pressure (increased preload). The elevated pressures are eventually transmitted to the pulmonary capillaries, leading to fluid transudation. Patients with cardiogenic pulmonary edema who continue to have respiratory distress, respiratory acidosis, and/or hypoxia while on a non-rebreather face mask delivering 100% oxygen should be placed on noninvasive positive-pressure ventilation (NPPV). NPPV in cardiogenic pulmonary edema patients decreases the need for intubation and enhances oxygenation via improvements in respiratory and cardiac parameters. noninvasive positive-pressure ventilation (NPPV) NPPV increases intrathoracic pressure; this results in reduced venous return, decreased right and left ventricular preload, and improved cardiac output (via the Frank-Starling relationship). NPPV also reduces LV afterload as the high intrathoracic pressure has a squeezing effect on the left ventricle, augmenting ventricular contraction. There is a subsequent reduction in the pressure gradient between the left ventricle and aorta, reducing the work (afterload) required for contraction (Choice D). NPPV augments inspiratory and expiratory flow, decreasing the work of breathing. Specifically, it unloads (and augments) the inspiratory muscles, increasing tidal volume and functional residual capacity (Choice A). Further, by re-expanding flooded alveoli, NPPV decreases dead space ventilation. There is a resultant reduction in the amount of ventilation/perfusion mismatch and improvements in alveolar (and therefore minute) ventilation (Choices B and E). Educational objective: Noninvasive positive-pressure ventilation in cardiogenic pulmonary edema patients enhances oxygenation via improvements in respiratory (↓dead space ventilation, ↑tidal volume, ↑alveolar/minute ventilation) and cardiac indices (↓preload, ↓afterload). __________ References: Noninvasive ventilation in acute cardiogenic pulmonary edema. (http://www.ncbi.nlm.nih.gov/pubmed/18614781)

Question 6

A 76-year-old man with chronic obstructive pulmonary disease is admitted to the intensive care unit for pneumonia.  On presentation in the emergency department, he had hypercapnia and hypoxic respiratory failure.  He was intubated and sedated.  After intubation, the patient's blood pressure dropped to 85/58 mm Hg and did not recover with intravenous fluid resuscitation.  A central venous catheter was placed and he was started on pressors.
Which of the following procedures is most likely to improve outcome in this patient?

Accepted Answer

Central venous catheters (CVCs) are the most common cause of iatrogenic bloodstream infection, which can significantly worsen patient outcomes. Recommendations to reduce the incidence of central line-associated blood stream infections (CLABSIs) include the following: Hand hygiene prior to catheter insertionUse of a catheter cart/kit that includes all necessary items for insertionChlorhexidine for insertion site cleaningMaximal sterile precautions (gown, cap, mask, gloves, sterile full-body drape)Removal of nonessential CVCs ("idle CVCs") Hand hygiene prior to catheter insertion Use of a catheter cart/kit that includes all necessary items for insertion Chlorhexidine for insertion site cleaning Maximal sterile precautions (gown, cap, mask, gloves, sterile full-body drape) Removal of nonessential CVCs ("idle CVCs") CLABSI risk increases with each additional day that the catheter remains in place. A recent study of patients not in the intensive care unit showed that health care providers did not know the reason that a CVC was maintained in >8% of patients. (Choices A, C, and D) Routine clinical testing can increase health care costs, has not proven beneficial for patient care, and may occasionally cause harm (eg, induce anemia requiring transfusion). Unnecessary testing may also lead to workup of incidental and non-clinically significant results. Daily routine laboratory testing is not advised; instead, testing should be performed based on specific clinical indications. (Choice E) Starting enteral nutrition in critically ill but hemodynamically stable patients within 48 hours has been shown to improve outcomes. However, it is recommended that enteral nutrition not be started in hemodynamically unstable patients who have not been fully resuscitated as it may lead to bowel ischemia. Educational objective: Risk for central line-associated bloodstream infections increases the longer a catheter remains in place. Critically ill patients should be assessed daily for the need for continued central venous access. __________ References: Making health care safer II: an updated critical analysis of the evidence for patient safety practices. (http://www.ncbi.nlm.nih.gov/pubmed/24423049)

Question 7

A 65-year-old man is admitted to the hospital for increasing shortness of breath and edema. Over the last 10 days, he has experienced progressively worsening shortness of breath occurring with modest exertion and a cough productive of a small amount of purulent sputum. He denies paroxysmal nocturnal dyspnea, orthopnea, fever, chills, and chest pain. He also reports a 4.5-kg (10-lb) weight gain. His medical problems include chronic obstructive pulmonary disease (COPD), congestive heart failure due to coronary artery disease, type 2 diabetes mellitus, hypertension, degenerative joint disease, and obesity. His blood pressure is 138/84 mm Hg, pulse is 96/min and regular, and respirations are 20/min. Pulse oximetry reveals an oxygen saturation of 94% while using nasal prongs at 2 liters of oxygen/min. His jugular venous pressure is 10-12 cm H₂O. Lung examination reveals diffusely decreased breath sounds with prolongation of the expiratory phase. There are no rales. Cardiac examination reveals an increased P2 and a grade 2/6 systolic murmur along the left sternal border. Abdominal examination is normal. There is 2-3+ bilateral pedal edema. He is treated with intravenous furosemide and azithromycin, and his symptoms are gradually improving. Laboratory results obtained 48 hours after admission are as follows: Which of the following is most likely the cause of his acid-base disorder?

Accepted Answer

This patient has a mixed acid-base disorder. He has alkalosis which can either be metabolic (high bicarbonate concentration) or respiratory (low PaCO2). Given his high bicarbonate concentration and high PaCO2, he has metabolic alkalosis, which sometimes complicates the course of diuretic therapy. One clue to the presence of a mixed acid-base disturbance is a lesser or greater degree of compensation than would be expected for the patient's primary acid-base disorder. In response to metabolic alkalosis, there is usually a 0.7 mm Hg increase in PaCO2 for each mEq/L increase in bicarbonate concentration. Therefore, in a patient with a bicarbonate level of 37 mEq/L, PaCO2 can increase up to a maximum of 50-55 mm Hg. This patient's PaCO2 of 63 mm Hg is significantly higher than would occur from metabolic alkalosis alone, suggesting the presence of underlying chronic respiratory acidosis, most likely due to chronic obstructive pulmonary disease (COPD). (Choice A) The acid-base disorder most commonly seen in association with diabetes is ketoacidosis. This patient is not acidemic and does not have an increase in his anion gap, making diabetic ketoacidosis implausible. The appropriate respiratory compensation to metabolic acidosis (not metabolic alkalosis) can be given by Winter's formula: PaCO2 = 1.5 × serum bicarbonate + 8 ± 2. (Choice B) With chronic respiratory acidosis from COPD, for every 10 mm Hg increase in PaCO2, the bicarbonate concentration increases by about 3 mEq/L. The degree of CO₂ retention in this patient would be expected to increase his bicarbonate concentration by approximately 8 mEq/L. His measured bicarbonate concentration is significantly higher, which suggests metabolic alkalosis. He is also alkalemic. The body does not "over-compensate" for any primary acid-base disorder, and the presence of alkalemia effectively excludes the simple acid-base disorder of respiratory acidosis. (Choice C) Congestive heart failure can be associated with several acid-base disorders depending upon the severity and associated comorbidities. Respiratory alkalosis is often seen due to the effect of hypoxemia to stimulate ventilation. Respiratory acidosis sometimes occurs when marked pulmonary edema is present. Since patients with heart failure are often treated with diuretics, metabolic alkalosis can also be seen. Rarely, lactic acidosis will be seen in association with cardiogenic shock. This patient's combined metabolic alkalosis and chronic respiratory acidosis are unlikely to be due to heart failure alone. (Choice E) Some diuretic agents can induce metabolic alkalosis. However, diuretic agents would not cause a combined metabolic alkalosis and respiratory acidosis. Educational objective: The presence of a mixed acid-base disorder is suggested by clinical history and when there is a lesser or greater degree of compensation than what typically occurs in response to the primary acid-base disorder. __________ References: Secondary responses to altered acid-base status: the rules of engagement. (http://www.ncbi.nlm.nih.gov/pubmed/20431042) Effect of metabolic alkalosis on respiratory function in patients with chronic obstructive lung disease. (http://www.ncbi.nlm.nih.gov/pubmed/21028)

Question 8

A 47-year-old man with known HIV infection is admitted for shortness of breath and non-productive cough.  He has not been adherent with his medications and has not received medical attention for two years.  His other medical problems include hepatitis C, lower extremity neuropathy, and tonic-clonic seizures.  His last seizure episode was 7 years ago.  He receives 2 L of intravenous normal saline in the emergency department and is started on trimethoprim-sulfamethoxazole and prednisone for presumed pneumocystis pneumonia.
Forty-eight hours later, his serum creatinine increased from 1.3 to 1.6 mg/dL.
His temperature is 37.8 C (100 F), blood pressure is 102/70 mm Hg supine and 105/68 mm Hg standing, and pulse is 112/min.  He has crackles in both posterior lung bases.  His liver is palpated 2 cm below the costal margin.  There is no peripheral edema.
Urinalysis results are shown below:

Which of the following is the most likely cause of his elevated creatinine?

Accepted Answer

Creatinine is an organic cation, and approximately 15% of urinary creatinine comes from tubular secretion. Other organic cations and anions, such as trimethoprim and cimetidine, can compete with creatinine for tubular secretion. By decreasing creatinine secretion, both trimethoprim and cimetidine can result in increased serum creatinine without decreasing the glomerular filtration rate (GFR). This increase is usually minor, in the range of 0.1-0.2 mg/dL, but can be up to 0.4-0.5 mg/dL. Other factors that can increase the serum creatinine without decreasing GFR include chemical interference by ketone bodies, cefoxitin, and flucytosine. (Choice A) AIDS nephropathy is typically associated with significant proteinuria, which is not seen in this patient. (Choice B) Interstitial nephritis is usually associated with more white cells and granular casts on urinalysis. Drug-induced early interstitial nephritis may also present with a rash, fever, eosinophilia, and eosinophiluria. (Choice C) Volume depletion with pre-renal injury causes enhanced renal tubular sodium conservation and a spot urinary sodium < 20 mEq/dL. This patient does not have orthostatic blood pressure changes and has a spot urinary sodium of 40 mEq/dL. (Choice D) Sulfamethoxazole crystalluria usually takes longer to develop, occurs in the setting of more acidic urine, and is often associated with the appearance of sulfa crystals in the urine. Educational objective: By decreasing creatinine secretion, both trimethoprim and cimetidine can result in an increased serum creatinine without decreasing the glomerular filtration rate. __________ References: Renal effects of trimethoprim in cyclosporine- and azathioprine-treated kidney allograft patients. (http://www.ncbi.nlm.nih.gov/pubmed/2677807) Trimethoprim-sulfamethoxazole revisited. (http://www.ncbi.nlm.nih.gov/pubmed/12588198)

Question 9

A 60-year-old woman is brought to the emergency department by her husband due to confusion.  She has been increasingly confused over the last 2 days.  The patient also has a 2-week history of excessive urination, heartburn, nausea, vomiting, and fatigue.  She has had no associated fever, chills, chest pain, or respiratory symptoms.  Medical history is notable for coronary artery disease, hypertension, and gastroesophageal reflux.  The patient takes several medications, including an over-the-counter medication for heartburn, but her husband does not recall their names.
Temperature is 37.2 C (99 F), blood pressure is 146/90 mm Hg, pulse is 90/min, and respirations are 16/min.  Pulse oximetry is 96% on room air.  Mucous membranes are dry.  The patient cannot recall 2 of 3 items acutely.  The lungs are clear with no cardiac murmurs or gallops.  She has no skin rashes.
Laboratory results are as follows:
 The patient's serum calcium rapidly improves with an infusion of normal saline.
Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_9725_14e0_853d_d1b73dd7bc52_MD0002_00 This patient has parathyroid hormone (PTH)-independent hypercalcemia (ie, hypercalcemia with a low or low-normal PTH level). In addition, she has renal insufficiency and alkalosis. Together, this triad is most consistent with milk-alkali syndrome (MAS). MAS is caused by excessive intake of calcium and absorbable alkali, most commonly due to the use of calcium carbonate preparations for osteoporosis or heartburn. The resulting hypercalcemia causes renal vasoconstriction with decreased glomerular blood flow and leads to increased natriuresis, with eventual volume depletion and metabolic alkalosis due to increased renal tubular bicarbonate resorption. Patients also frequently have hypophosphatemia due to the phosphate-binding effect of calcium carbonate. The risk of MAS is increased in patients taking medications that decrease glomerular filtration (eg, ACE inhibitors/angiotensin II receptor blockers, nonsteroidal anti-inflammatory drugs). Manifestations can range from incidental hypercalcemia, to acute symptomatic hypercalcemia, to chronic kidney disease with metastatic calcification. The hypercalcemia in MAS corrects promptly with isotonic saline infusion and (if necessary) furosemide. (Choice A) Granulomatous diseases (eg, sarcoidosis) cause hypercalcemia due to increased production of 1,25-dihydroxyvitamin D and increased intestinal calcium absorption. This patient's 1,25-dihydroxyvitamin D level is at the low end of normal. (Choice B) Malignancy-induced hypercalcemia is possible in this patient but less likely than MAS in light of her history of taking an over-the-counter medication for heartburn (most likely calcium carbonate), coexistent alkalosis, and rapid correction with normal saline. (Choice D) This patient has a suppressed PTH level, which rules out primary hyperparathyroidism. (Choice E) Thiazide diuretics can cause hypercalcemia due to increased renal reabsorption of calcium. Although thiazides can increase the risk for MAS, the hypercalcemia attributable to thiazides is usually very mild and rarely symptomatic. Educational objective: Milk-alkali syndrome is characterized by parathyroid hormone-independent hypercalcemia, renal insufficiency, and metabolic alkalosis. It is usually caused by excessive ingestion of calcium carbonate. The risk is increased in patients taking medications that decrease glomerular filtration. Treatment includes isotonic saline infusion and furosemide. __________ References: Milk-alkali syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/19252114)

Question 10

A 41-year-old previously healthy man is admitted to the hospital with 3 days of nausea, vomiting, and abdominal pain. He was found to have acute necrotizing pancreatitis due to alcohol use. His hospital course was complicated by hypotension requiring 8 L of intravenous fluids. He subsequently developed bilateral infiltrates and refractory hypoxemia requiring intubation and mechanical ventilation. While in the intensive care unit, he develops low-grade fevers and worsening hypoxemia requiring 100% FiO₂ and positive end-expiratory pressure of 12. Cultures are obtained and antibiotic coverage is broadened. His blood and urine cultures show no growth 48 hours later. However, sputum culture grows Candida species. Laboratory results are as follows: A repeat chest x-ray shows persistent bilateral infiltrates and new small bilateral pleural effusions. Which of the following is the most appropriate next step in managing this patient's positive sputum culture?

Accepted Answer

Bronchial tree colonization with Candida species is common in critically ill patients receiving mechanical ventilation, but primary Candida pneumonia and invasive disease are rare. Candida pneumonia is usually not due to aspiration of oropharyngeal secretions but rather to hematogenous spread from disseminated candidiasis (eg, osteomyelitis, septic arthritis, or endocarditis). As a result, diagnosis of Candida pneumonia requires histopathological confirmation. Current guidelines do not recommend antifungal treatment or repeat cultures for immunocompetent patients with Candida from respiratory sputum or bronchoalveolar lavage unless they are immunocompromised (Choice D). Antifungal treatment is also reserved for immunocompetent patients with a primary Candida infection at another site who develop new pulmonary lesions suspicious for hematogenous spread (Choices A and B). Fluconazole is preferred for treating candidemia, but echinocandins (eg, micafungin) are recommended in patients with severe illness or recent azole exposure. (Choice E) Thoracentesis is not indicated in patients with small bilateral pleural effusions. Educational objective: Growth of Candida from respiratory secretions rarely indicates invasive candidiasis and should not be treated with antifungal therapy. __________ References: Clinical practice guidelines for the management of candidiasis: 2009 update by the Infectious Diseases Society of America. (http://www.ncbi.nlm.nih.gov/pubmed/19191635)

Question 11

A 58-year-old man with a history of chronic obstructive pulmonary disease develops acute respiratory distress syndrome secondary to community-acquired pneumonia. He has been stable on mechanical ventilation with peak and plateau pressures <30 cm H₂O, and his oxygen requirements have decreased over the past 2 days. On his third day in the intensive care unit, he is ventilated on assist control mode, with a respiratory rate of 16/min, positive end-expiratory pressure of 10 cm H₂O, and FiO₂ of 0.6 (60%). The patient's peak pressure ventilator alarm has been on for the past 10 minutes and his respirations appear more labored. Pulse has increased from 85 to 120/min, and respiratory rate has increased from 16 to 32/min. The peak pressure is 44 cm H₂O and the plateau pressure is 24 cm H₂O. On chest auscultation, breath sounds are coarse and mildly decreased on the left side. Which of the following actions would be most likely to improve the patient's current symptoms?

Accepted Answer

11ec193a_971d_4ca2_853d_556d244e9a90_MD0002_00 Measurement of airway pressures can be useful in the management of mechanically ventilated patients: The peak airway pressure is the maximum pressure measured as the tidal volume is being delivered. It equals the sum of the resistive pressure (flow × resistance) and the plateau pressure. (Peak airway pressure = resistive pressure + plateau pressure). Peak pressures are dynamic pressures that measure the resistance to flow of air delivered from the ventilator and the amount of pressure needed to inflate the lung. Peak airway pressure is ideally maintained ≤35 cm H₂O to minimize risk of barotrauma.The plateau pressure is the pressure measured during an inspiratory hold maneuver, when pulmonary airflow and therefore resistive pressure are both 0. It equals the sum of the elastic pressure (elastance × tidal volume) and positive end-expiratory pressure. (Plateau pressure = elastic pressure + positive end-expiratory pressure). Plateau pressures are static lung pressures that give an estimate of lung compliance; a typical goal is ≤30 cm H₂O. Because elastance and compliance are inversely related, decreased compliance (eg, pulmonary fibrosis) causes stiffer lungs and higher elastic pressure. The peak airway pressure is the maximum pressure measured as the tidal volume is being delivered. It equals the sum of the resistive pressure (flow × resistance) and the plateau pressure. (Peak airway pressure = resistive pressure + plateau pressure). Peak pressures are dynamic pressures that measure the resistance to flow of air delivered from the ventilator and the amount of pressure needed to inflate the lung. Peak airway pressure is ideally maintained ≤35 cm H₂O to minimize risk of barotrauma. The peak airway pressure is the maximum pressure measured as the tidal volume is being delivered. It equals the sum of the resistive pressure (flow × resistance) and the plateau pressure. (Peak airway pressure = resistive pressure + plateau pressure). Peak pressures are dynamic pressures that measure the resistance to flow of air delivered from the ventilator and the amount of pressure needed to inflate the lung. Peak airway pressure is ideally maintained ≤35 cm H₂O to minimize risk of barotrauma. The plateau pressure is the pressure measured during an inspiratory hold maneuver, when pulmonary airflow and therefore resistive pressure are both 0. It equals the sum of the elastic pressure (elastance × tidal volume) and positive end-expiratory pressure. (Plateau pressure = elastic pressure + positive end-expiratory pressure). Plateau pressures are static lung pressures that give an estimate of lung compliance; a typical goal is ≤30 cm H₂O. Because elastance and compliance are inversely related, decreased compliance (eg, pulmonary fibrosis) causes stiffer lungs and higher elastic pressure. The plateau pressure is the pressure measured during an inspiratory hold maneuver, when pulmonary airflow and therefore resistive pressure are both 0. It equals the sum of the elastic pressure (elastance × tidal volume) and positive end-expiratory pressure. (Plateau pressure = elastic pressure + positive end-expiratory pressure). Plateau pressures are static lung pressures that give an estimate of lung compliance; a typical goal is ≤30 cm H₂O. Because elastance and compliance are inversely related, decreased compliance (eg, pulmonary fibrosis) causes stiffer lungs and higher elastic pressure. Increased peak pressure associated with an unchanged plateau pressure, as seen in this patient, suggests a pathologic process causing increased airway resistance without a change in lung compliance. The most likely cause of increased resistance to flow in this patient is a mucus plug, which may be improved with airway or endotracheal tube suctioning. (Choices B and C) Bronchospasm and the patient biting on the endotracheal tube are other causes of elevated peak pressures without an increase in plateau pressures. However, bronchospasm is expected to cause wheezing on examination. Increasing the sedation can help prevent biting of the endotracheal tube, but a mucus plug is more likely in this patient with unilateral decreased breath sounds and evidence of respiratory distress (eg, tachypnea). (Choices D and E) Intravenous furosemide and needle decompression of the left chest are treatments for pulmonary edema and tension pneumothorax, respectively. These conditions lead to decreased pulmonary compliance and would be suggested by an elevation in both plateau and peak airway pressures. Educational objective: Peak and plateau pressures are derived from the ventilator according to the different clinical states of the airway, lung, and chest wall. Peak pressures, also known as dynamic pressures, measure the resistance to flow of air delivered from the ventilator and the amount of pressure needed to inflate the lung. Plateau pressures are static lung pressures, measured during an inspiratory hold, that give an estimate of lung compliance. __________ References: Mechanical ventilation. (http://www.ncbi.nlm.nih.gov/pubmed/18655948)

Question 12

A 39-year-old man is admitted to the hospital for acute alcoholic pancreatitis.  His initial APACHE II score was 20, suggestive of severe disease.  Within the first 48 hours, he received a total of 10 liters of intravenous fluid resuscitation.  Because of decreasing oxygenation, he was intubated and started on mechanical ventilation.  Due to increased oxygen requirements, both PEEP and FiO2 were progressively increased.  Over the past 12 hours, his urine output decreased and his serum creatinine increased from 1.2 mg/dL at admission to 2.2 mg/dL at present.
His blood pressure is 110/70 mm Hg and pulse is 98/min.  Jugular venous pressure is elevated.  Lung examination reveals bilateral crackles at the lung bases.  His abdomen is diffusely tender and tensely distended.  Bowel sounds are diminished.  There are no flank or periumbilical ecchymoses.  There is 3+ pitting edema to mid-thighs bilaterally.
Urinalysis results are as follows:

Which of the following would most likely establish the cause of the acute kidney injury?

Accepted Answer

11ec193a_9722_55b9_853d_01364fda3b46_MD0002_00 This patient's presentation is consistent with likely intra-abdominal hypertension (IAH) causing abdominal compartment syndrome (ACS). Intra-abdominal hypertension is defined as pressure > 12 mm Hg; and ACS is defined as IAH with new organ dysfunction. Primary ACS is due to abdominal pelvic disease, while secondary ACS is usually due to extra-abdominal conditions (e.g., burns). Abdominal compartment syndrome occurs in patients receiving large amounts of fluids and almost any organ can be affected (especially the kidney due to its anatomical position). While the exact pathophysiology is unknown, acute kidney injury is likely due to decreased renal blood flow and elevated renal venous pressure. A diagnosis of ACS can rapidly be confirmed by measuring hydrostatic pressure within the bladder, which is strongly correlated with intra-abdominal pressure. Lowering intra-abdominal hydrostatic pressure often quickly improves renal function; however, most patients require surgical decompression. Abdominal compartment syndrome has a mortality rate ranging as high as 40-100%. (Choice A) An abdominal CT scan in ACS patients is fairly non-specific (e.g., massive abdominal distention, direct renal compression or displacement, bowel wall thickening). An abdominal CT scan may help show pancreatic necrosis or a local complication from pancreatitis, but it is unlikely to establish the cause of this patient's acute kidney injury. (Choice B) The fractional excretion of sodium (FE_Na) can differentiate between poor kidney perfusion (FE_Na < 1%)) and renal tubular necrosis (FE_Na > 2%). However, FE_Na is neither sensitive nor specific in ACS and is usually < 2%. (Choice D) An ultrasound of the kidneys and bladder to further evaluate AKI would be indicated if the bladder pressure is normal, but it is unlikely to be of much help in this patient. (Choice E) Complement levels can help differentiate causes of rapidly progressive glomerulonephritis, but this patient's lack of proteinuria makes this less likely. Educational objective: Intra-abdominal hypertension and abdominal compartment syndrome often follow aggressive volume expansion in patients with trauma, septic shock, or other conditions. Abdominal compartment syndrome can cause multi-organ failure, including acute kidney injury. Measurement of hydrostatic pressure within the bladder is preferred to assess intra-abdominal pressure. Most patients require surgical decompression. __________ References: Intra-abdominal hypertension and abdominal compartment syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/21184922) Is the evolving management of intra-abdominal hypertension and abdominal compartment syndrome improving survival? (http://www.ncbi.nlm.nih.gov/pubmed/20095067)

Question 13

A 64-year-old man with a moderate right-sided pleural effusion seen on initial chest x-ray was admitted for pneumonia. Initial admission testing showed a white blood cell count of 14,800/mm³ with 92% neutrophils. He was started on ceftriaxone and azithromycin, and his symptoms improved over the next few hours. The patient's other medical problems include hypertension, hyperlipidemia, and hypothyroidism. He is a former smoker with a 25-pack-year history. His blood pressure this morning is 142/90 mm Hg, pulse is 88/min, and respirations are 16/min. Oxygen saturation is 93% on room air. The patient speaks in full sentences, without respiratory distress. Jugular venous pressure is estimated at 5 cm H₂O. Lung examination shows decreased breath sounds, decreased tactile fremitus, and dullness to percussion less than halfway up the right chest. A soft second heart sound and 3/6 systolic ejection murmur are heard at the upper right sternal border with radiation to the carotids. The white blood cell count is 12,200/mm³ with 78% neutrophils. A right lateral decubitus chest x-ray demonstrates a 20-mm free-flowing effusion. Further imaging shows an effusion in the right base without pleural thickening. Which of the following is the best next step in management of this patient?

Accepted Answer

11ec193a_971c_3b30_853d_ddc4a1b53cb4_MD0002_00 Parapneumonic effusions can occur in the adjacent pleural space in up to 40% of bacterial pneumonias. Most parapneumonic effusions are minimal and resolve with antibiotics. Effusions that are free-flowing and ≤10 mm on lateral decubitus film should be observed with serial imaging alone as they are most likely to resolve with antibiotics. Effusions >10 mm need to be evaluated further with chest imaging (ultrasonography or chest CT). Loculations, pleural thickening, and large (>½ hemithorax) effusions are considered high-risk features as they are associated with a higer rate of adverse outcomes. Diagnostic thoracentesis is recommended for effusions >10 mm with no high-risk features on imaging, as in this patient. Negative Gram stain, negative culture, and pH >7.2 with glucose ≥60 mg/dL on fluid analysis show that the effusion is uncomplicated and may respond to antibiotics alone. By contrast, complicated effusions (positive Gram stain or culture, pH <7.2, glucose <60 mg/dL) require drainage, usually with tube thoracostomy; similarly, effusions >10 mm with high-risk features require drainage (Choice C). Drainage also may be needed if there is no clinical improvement with antibiotics, the effusions persist on serial imaging, or the patient subsequently develops any high-risk features. (Choice A) Furosemide may decrease pleural effusions due to heart failure or renal disease. However, this patient's normal jugular venous pressure and absence of peripheral edema make these less likely. (Choices B and E) Although this patient has noted clinical improvement on current antimicrobial therapy, he needs a diagnostic thoracentesis (eg, to exclude a complicated effusion and to potentially identify the causative organism) as the pleural effusion is >10 mm. Antibiotics may need to be changed after the suspected organism and its antibiotic susceptibility are identified. Educational objective: Free-flowing effusions ≤10 mm usually resolve with antibiotic therapy alone. Larger effusions should be imaged with ultrasound and/or CT. Effusions without high-risk features (loculation, >½ hemithorax, pleural thickening) should undergo diagnostic thoracentesis. Effusions with high-risk features or pH <7.2, glucose <60 mg/dL, or positive Gram stain/culture should be drained. __________ References: Parapneumonic pleural effusion and empyema. (http://www.ncbi.nlm.nih.gov/pubmed/18367849) Management of infectious processes of the pleural space: a review. (http://www.ncbi.nlm.nih.gov/pubmed/22536502)

Question 14

A 35-year-old woman underwent ultrasound evaluation for dyspepsia. No gallstones were identified; however, the ultrasonogram showed three cortical cysts in the right kidney, two in the left kidney, and two liver cysts. She is in good health and has no urinary symptoms. Her father died at the age of 52 from a stroke. There is no family history of kidney disease. Her blood pressure is 132/78 mm Hg and pulse is 89/min. Her BMI is 29 kg/m². Physical examination is unremarkable. Her serum creatinine is 0.8 mg/dL. Urinalysis is normal. Which of the following is the most likely diagnosis?

Accepted Answer

11ec193a_9723_672b_853d_a1edd1e0fd87_MD0002_00 This patient's number of kidney cysts, liver cysts, and possible family history of cerebral aneurysm (father's stroke) is consistent with likely autosomal dominant polycystic kidney disease (ADPKD). The characteristic ultrasound findings for ADPKD are listed in the above table. Autosomal dominant polycystic kidney disease is frequently associated with hepatic cysts (up to 20-80% of patients), pancreatic cysts, cerebral aneurysms (5-20% of patients), cardiac valvular disease (e.g., mitral or aortic regurgitation), and diverticulosis. Genetic testing should be performed in this patient to confirm the diagnosis. Treatment is mainly supportive with close follow-up to monitor renal function and treatment of associated conditions (e.g., hypertension). (Choice A) Acquired cystic disease presents with small cysts in advanced chronic kidney disease due to non-cystic causes. Unlike ADPKD, acquired cystic disease usually presents with smaller kidneys with a smooth contour and no family history. (Choice C) Multiple benign cysts at this age are less common, rarely bilateral, and are usually not associated with liver cysts. (Choice D) Medullary sponge kidney typically presents with dilated collecting ducts in the medullary pyramids that is sometimes confused with the radiographic appearance of ADPKD. However, medullary sponge kidney does not involve the cortex, while ADPKD usually does. (Choice E) Tuberous sclerosis is usually associated with renal angiomyolipomas (70% of cases), multiple renal cysts (30% of cases), skin lesions (e.g., hypopigmented macules), and CNS disease (e.g., subependymal giant cell astrocytoma). This patient's lack of skin findings and associated liver cysts make tuberous sclerosis unlikely. Educational objective: Ultrasound findings of multiple renal cysts may suggest autosomal dominant polycystic kidney disease, which is associated with several extra-renal manifestations (e.g., hepatic cysts and intracerebral aneurysms). __________ References: Unified criteria for ultrasonographic diagnosis of autosomal dominant polycystic kidney disease. (http://www.ncbi.nlm.nih.gov/pubmed/18945943) Hepatic and renal manifestations in autosomal dominant polycystic kidney disease: a dichotomy of two ends of a spectrum. (http://www.ncbi.nlm.nih.gov/pubmed/21978978)

Question 15

A 46-year-old man with known kyphoscoliosis complains of fatigue and progressive shortness of breath over the last year. He can barely walk a block without becoming "short-winded." During his last evaluation, his vital capacity was 40% of predicted value and his FEV₁/FVC ratio was 85%. He does not use tobacco, alcohol, or illicit drugs. The patient's blood pressure is 144/78 mm Hg and pulse is 78/min. Oxygen saturation is 90% on room air. The angle of scoliosis is > 65 degrees and kyphosis deformity is above T10. The remainder of physical examination is unremarkable. Transthoracic echocardiogram shows normal left ventricular function, mild right ventricular enlargement, and estimated pulmonary artery systolic pressure of 55 mm Hg. Pulmonary function test results are unchanged from prior testing. This patient is most likely to benefit from which of the following?

Accepted Answer

Diseases of the chest wall, such as ankylosing spondylitis, pectus excavatum, and kyphoscoliosis, and morbid obesity cause a restrictive pattern of respiratory impairment that can lead to respiratory failure. Patients with kyphoscoliosis and deformity above T10 are at higher risk for respiratory failure due to compromised chest wall mechanics. pectus excavatum Total lung capacity, vital capacity, and functional residual capacity are reduced due to decreased chest wall compliance. Lung compliance also decreases eventually due to atelectasis and air trapping, causing increased work of breathing. This may lead to respiratory fatigue and even failure. Patients are also prone to nocturnal hypoventilation leading to apneic events. They can subsequently develop pulmonary hypertension and cor pulmonale. Patients at risk for respiratory failure should be advised to avoid extremes of temperature, humidity, fatigue, sedatives, and opiates. They should also receive influenza and pneumococcal vaccines. Treatment of respiratory impairment due to chest wall disease is usually supportive with pulmonary rehabilitation and intermittent nocturnal or longer term use of noninvasive positive-pressure ventilation (NPPV). NPPV eliminates hypoxemia and obstructive apneas and improves lung volumes and respiratory function. Some studies have shown improved mortality in these patients. (Choice A) Bracing may be used in idiopathic scoliosis for skeletally immature adolescents but is contraindicated in adults. (Choice B) Inhaled corticosteroids are not helpful in patients with respiratory compromise from chest wall disease. (Choices D and E) Anticoagulation is recommended for patients with idiopathic or hereditary pulmonary hypertension (PH), drug-induced PH, and chronic thromboembolic PH. PH due to chest wall disorders usually does not benefit from vasodilator or chronic anticoagulation therapy. NPPV is the only therapy proven to improve dyspnea and sleep disturbances and may even partially reverse cor pulmonale. Educational objective: The intermittent use of noninvasive positive-pressure ventilation in patients with chronic respiratory failure from chest wall disease has been shown to improve dyspnea, sleep disturbances, and mortality. It also may partially reverse cor pulmonale. __________ References: Treatment of chronic respiratory failure in kyphoscoliosis: oxygen or ventilation? (http://www.ncbi.nlm.nih.gov/pubmed/14516146) Lung function in congenital kyphosis and kyphoscoliosis. (http://www.ncbi.nlm.nih.gov/pubmed/17473639) Effect of long term intermittent nocturnal non-invasive positive pressure ventilation on patient with severe kyphoscoliosis and hypoxemia. (http://www.ncbi.nlm.nih.gov/pubmed/21686653) Pulmonary diseases and the heart. (http://www.ncbi.nlm.nih.gov/pubmed/18086941)

Question 16

A 45-year-old hospitalized man is evaluated for worsening kidney function. The patient has a history of alcoholic cirrhosis and was admitted 3 days ago due to progressive abdominal pain and lethargy. Evaluation revealed asterixis and 300/mm³ of neutrophils in the ascitic fluid. He was started on intravenous cefotaxime and oral lactulose for treatment of spontaneous bacterial peritonitis complicated by hepatic encephalopathy. The patient's symptoms have gradually improved with treatment, but his serum creatinine has increased from 0.9 mg/dL on admission to 2.1 mg/dL now. Urine output during the last 24 hours is 450 mL. He has no history of kidney disease or other medical problems. The patient's home diuretic therapy with furosemide and spironolactone had been initially continued during the hospitalization but was stopped yesterday. He stopped drinking alcohol after being diagnosed with cirrhosis 3 years ago and does not use tobacco. Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 96/min, and respirations are 18/min. The patient is somnolent but easily roused. There is mild scleral icterus, and jugular venous pressure is normal. Lungs are clear to auscultation. The abdomen is soft, moderately distended with ascites, and nontender. Bowel sounds are normoactive. There is 2+ bilateral lower-extremity pitting edema. Laboratory results are as follows: Renal ultrasonography shows no hydronephrosis. Which of the following is the most appropriate next step in management of this patient's renal dysfunction?

Accepted Answer

11ec193a_9720_a805_853d_03b31129714f_MD0002_00 This patient's advanced liver disease and rapidly developing acute kidney injury (AKI) raise suspicion for hepatorenal syndrome (HRS); spontaneous bacterial peritonitis (SBP) is a common precipitant of HRS. HRS likely results from increased activity of circulating vasodilators (eg, nitric oxide), leading to arterial vasodilation in the splanchnic and systemic circulation. The consequent decrease in renal perfusion pressure triggers compensatory renal vasoconstriction and marked reduction in glomerular filtration rate and urine production. HRS is largely a diagnosis of exclusion, which requires the following: Evidence of liver disease (usually cirrhosis) with portal hypertensionAKI in the absence of other causes (eg, shock, nephrotoxic agents)Urine red blood cells <50/hpf and urine protein <500 mg/dayLack of improvement in AKI after 48 hours of diuretic cessation and volume expansion with albumin Evidence of liver disease (usually cirrhosis) with portal hypertension AKI in the absence of other causes (eg, shock, nephrotoxic agents) Urine red blood cells <50/hpf and urine protein <500 mg/day Lack of improvement in AKI after 48 hours of diuretic cessation and volume expansion with albumin This patient requires a diagnostic trial of intravenous albumin. If there is no improvement in renal function, HRS is diagnosed, and midodrine (a selective alpha-1 adrenergic agonist) and octreotide (a somatostatin analogue that reduces splanchnic vasodilation) can be added to treatment. Alternately, norepinephrine may be used for patients in an intensive care unit. These therapies typically act as a temporizing measure until hepatic function might be restored (eg, liver transplantation, spontaneous recovery of acute liver failure). (Choice A) Antibiotic discontinuation is appropriate for suspected acute interstitial nephritis; however, the absence of white blood cells on urinalysis makes this unlikely. This patient should continue cefotaxime to ensure sufficient treatment of SBP. (Choice C) Large-volume paracentesis (LVP) should be considered for renal failure due to suspected abdominal compartment syndrome; however, this patient's soft abdomen makes the diagnosis unlikely. In addition, chronic ascites may protect against abdominal compartment syndrome due to changes in abdominal wall compliance. In this patient with suspected HRS, LVP may further decrease renal perfusion and should be avoided at this time. (Choice D) Restarting furosemide is likely to cause intravascular volume depletion and lead to worsening renal dysfunction. Diuretics do not cause HRS but should be held in suspected HRS to allow a chance for renal recovery. (Choice E) Transjugular intrahepatic portosystemic shunts (TIPS) may improve renal function in some patients with HRS. However, due to the risk of complications and often poor outcome despite the procedure, TIPS is generally considered a last resort for patients who fail medical management. In addition, this patient's Model for End-Stage Liver Disease (MELD) score of >18 predicts poor 3-month survival following TIPS. (MELD) Educational objective: Hepatorenal syndrome presents with renal dysfunction and bland urine sediment in patients with advanced liver disease and portal hypertension. A 48-hour trial of diuretic cessation and volume expansion with albumin is required for the diagnosis. __________ References: Hepatorenal syndrome: Current concepts related to diagnosis and management. (http://www.ncbi.nlm.nih.gov/pubmed/27236146) Hepatorenal syndrome: Update on diagnosis and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/26558188) Diagnosis and management of acute kidney injury in patients with cirrhosis: Revised consensus recommendations of the International Club of Ascites. (http://www.ncbi.nlm.nih.gov/pubmed/25638527)

Question 17

A 78-year-old woman is admitted to the intensive care unit (ICU) with confusion, fever, hypotension, and tachypnea.  She is intubated and started on antibiotics for septic shock caused by a urinary tract infection.  Norepinephrine infusion is started via an internal jugular venous catheter.  The ventilator is set on continuous mandatory ventilation (CMV) mode and the patient is sedated with midazolam and fentanyl infusions.  Chest x-ray shows mild subsegmental atelectasis and appropriate positioning of endotracheal and orogastric tubes.
Which of the following is likely to decrease this patient's length of stay in the ICU and reduce the number of days she requires mechanical ventilation?

Accepted Answer

Multiple meta-analyses have shown that use of sedation protocols (daily interruption/algorithm-based sedation) reduces duration of mechanical ventilation and length of stay in the intensive care unit (ICU). Both techniques aim to minimize the total sedative dose. Some trials have shown improved one-year mortality. Sedation interruption allows for a daily spontaneous breathing trial and assessment of the patient's neurologic status and may reduce the need for neurodiagnostic testing. (Choice B) Studies of early tracheostomy in medical ICU patients have shown that it has no benefit and may even cause a worse outcome. (Choices C and D) Low tidal volume ventilation with higher positive end-expiratory pressure and neuromuscular blockade may be beneficial in patients with acute respiratory distress syndrome (ARDS). This patient likely has metabolic acidosis with respiratory compensation causing tachypnea. There is no evidence of ARDS. (Choice E) There is no evidence to suggest that synchronized intermittent mandatory ventilation is a better mode of mechanical ventilation than continuous mandatory ventilation. Educational objective: Protocolized sedation refers to the use of a sedation algorithm or daily sedation interruption. It has been shown to reduce duration of mechanical ventilation and length of intensive care unit stay. __________ References: Treatment algorithms in critical care: do they improve outcomes? (http://www.ncbi.nlm.nih.gov/pubmed/21507794)

Question 18

A 52-year-old woman develops cardiac arrest while hospitalized for the treatment of a pulmonary embolism. Advanced cardiac life support (ACLS) measures, including external chest compressions and endotracheal intubation, are implemented. After the airway is secured, a waveform capnograph is attached to the endotracheal tube and shows that the end-tidal partial pressure of CO₂ (EtCO₂) is 16 mm Hg. Cardiopulmonary resuscitation is continued along ACLS guidelines. After approximately 5 minutes of resuscitation, the EtCO₂ rapidly increases to 38 mm Hg. Which of the following is the most likely explanation for the change in this patient's capnography finding?

Accepted Answer

Capnography is the measurement of the partial pressure of CO₂ in the exhaled breath over time. The maximum CO₂ concentration at the end of each tidal breath (end-tidal [Et] CO₂) can provide information about ventilation and perfusion in patients in cardiac arrest undergoing cardiopulmonary resuscitation (CPR). The increase in cardiac output with the return of spontaneous circulation (ROSC) causes rapid transport of CO₂ accumulated in tissues during cardiac arrest to the lungs. This is detected as a sudden rise in EtCO₂ on capnography and is the earliest indicator of ROSC, occurring even before a pulse can be palpated. This technology virtually eliminates the need to stop CPR to check for a palpable pulse, reducing interruptions in cardiac compressions. In addition, recent studies have indicated that EtCO₂ can help determine prognosis during cardiac arrest. Patients with an EtCO₂ of ≤10 mm Hg after 20 minutes of CPR are highly unlikely to achieve ROSC. (Choices A and B) Esophageal intubation or a kinked endotracheal tube leads to ineffective ventilation. The EtCO₂ fails to rise despite effective CPR or ROSC. (Choice C) EtCO₂ levels reflect pulmonary blood flow and can be used as a noninvasive measure of cardiac output during CPR. High-quality chest compressions increase cardiac output and systemic and pulmonary perfusion causing a rise in EtCO₂, although this change is gradual. Poor quality chest compressions would cause a fall rather than a sudden increase in EtCO₂. (Choice E) Signs of right mainstem endobronchial intubation include an asymmetric rise in the chest wall during inflation and the absence of left-sided breath sounds. Regardless of tube positioning, a sudden rise in EtCO₂ during CPR suggests ROSC. Educational objective: A sudden rise in end-tidal CO₂ is the earliest indicator of return of spontaneous circulation in patients in cardiac arrest undergoing cardiopulmonary resuscitation. __________

Question 19

A 70-year-old woman is admitted to the hospital with a fractured hip after a fall.
Laboratory results are as follows:

Which of the following medications is most likely responsible for her acid-base abnormality?

Accepted Answer

11ec193a_9723_dc5d_853d_830d04791267_MD0002_00 This patient presents with non-anion gap metabolic acidosis, which can be caused by numerous agents. Carbonic anhydrase inhibitors, including acetazolamide (used for glaucoma) and topiramate (used for seizures and migraine headaches), typically cause bicarbonate diuresis with resultant non-anion gap metabolic acidosis. Many of the other implicated agents cause mild forms of renal tubular acidosis with accompanying non-anion gap metabolic acidosis, sometimes due to interstitial nephritis. (Choices B and D) Neither of these agents have been known to cause renal tubular acidosis or non-anion gap metabolic acidosis. (Choice C) Metformin has been associated with lactic acidosis that causes an anion gap metabolic acidosis. (Choice E) Zoledronic acid has rarely been associated with acute kidney injury, but causes neither renal tubular acidosis nor non-anion gap metabolic acidosis. Educational objective: Several pharmacologic agents are associated with non-anion gap metabolic acidosis. Acetazolamide inhibits carbonic anhydrase and typically causes bicarbonate diuresis with a non-anion gap metabolic acidosis. __________ References: Acetazolamide and symptomatic metabolic acidosis in mild renal failure. (http://www.ncbi.nlm.nih.gov/pubmed/6799050) Effect of topiramate on acid-base balance: extent, mechanism and effects. (http://www.ncbi.nlm.nih.gov/pubmed/19916989)

Question 20

A 65-year-old woman comes to the emergency department due to worsening cough and difficulty breathing.  The patient had similar symptoms a month ago and was found to have right-sided pneumonia.  The symptoms resolved with antibiotic treatment but recurred 2 days ago.  During the previous hospitalization, the patient also reported progressive muscle weakness and fatigue of several months' duration.  She subsequently underwent muscle biopsy, which revealed dermatomyositis; oral prednisone therapy was initiated 2 weeks ago.  She still has significant muscle weakness.  The patient also has had poor oral intake and frequent coughing while eating, and has lost 6.8 kg (15 lb) over the last 3 months.  The patient feels mildly depressed but has had no suicidal ideation.  She is a lifelong nonsmoker and does not drink alcohol.
Temperature is 38.6 C (101.5 F), blood pressure is 122/78 mm Hg, pulse is 89/min, and respirations are 20/min.  Bronchial breath sounds and rhonchi are present over the right lung base.  Muscle strength is moderately decreased in the proximal muscles.  There is a scaly skin rash over the extensor surfaces of both hands.
Laboratory results are as follows:
 Chest x-ray shows a right lower lobe lung infiltrate.
Which of the following is most likely responsible for this patient's pulmonary symptoms?

Accepted Answer

11ec193a_9726_4d64_853d_c7720ea2ddb9_MD0002_00 Dermatomyositis can cause weakness of the oropharyngeal and striated muscles in the upper third of the esophagus. This may lead to dysphagia for both solids and liquids and aspiration with recurrent pneumonia, as seen in this patient. Associated findings may include hoarseness and a nasal quality to the voice. Dermatomyositis-related dysphagia can be evaluated with manometry and a videofluoroscopic swallowing study, which typically shows pharyngeal pooling and nasal regurgitation. Treatment initially involves patient education on aspiration risk, elevation of the head of the bed, and semi-thick diets. Dysphagia may respond to treatment of the underlying myopathy with systemic glucocorticoids, although this is not well studied. Patients who are refractory to conservative measures may require a nasopharyngeal or gastric feeding tube for nutrition and airway protection. (Choice B) Impaired mucociliary clearance is common in smokers and is also seen in a variety of disorders, including Sjögren syndrome, cystic fibrosis, and primary ciliary dyskinesia. This patient is a lifelong nonsmoker and does not have any of these conditions. Although patients with impaired mucociliary clearance have an increased incidence of pulmonary infections, recurrent right lower lobe pneumonia suggests aspiration. (Choice C) Mycobacterial infection typically presents with upper-lobe disease (reactivation tuberculosis) or perihilar infiltrates (primary tuberculosis) with hilar adenopathy. This patient's initial improvement with antibiotics and chest x-ray findings make this less likely. (Choice D) Necrotizing vasculitis is seen in polyarteritis nodosa, eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), rheumatoid arthritis, systemic lupus erythematosus, scleroderma, and granulomatosis with polyangiitis (formerly Wegener granulomatosis), but is not common in dermatomyositis. Vasculitis also often causes acute/chronic kidney injury, which is not seen in this patient. (Choice E) Dermatomyositis is associated with interstitial lung disease, including interstitial pneumonia. However, examination typically shows fine ("Velcro") crackles, and imaging would show diffuse reticulonodular interstitial opacities, predominantly at the lung bases. Educational objective: Dermatomyositis can cause weakness of the oropharyngeal and striated muscles in the upper third of the esophagus. This may lead to dysphagia for both solids and liquids and aspiration with recurrent pneumonia. __________ References: Review article: the gastrointestinal complications of myositis. (http://www.ncbi.nlm.nih.gov/pubmed/19886949) Oropharyngeal dysphagia in dermatomyositis: associations with clinical and laboratory features including autoantibodies. (http://www.ncbi.nlm.nih.gov/pubmed/27167831)

Exam 2: In-patient Facilities

A 70-year-old woman is admitted to the hospital with a fractured hip after a fall. Laboratory results are as follows: Which of the following medications is most likely responsible for her acid-base abnormality?