A 36-year-old woman has increasing nausea and headaches 12 hours after a right-sided percutaneous nephrolithotomy for staghorn calculi. The procedure involved ultrasonic lithotripsy followed by fragment removal using a flexible nephroscope. The patient spent a prolonged period in recovery and has been drowsy since returning to the ward. She is receiving intermittent morphine for pain control. She also received intravenous ceftriaxone after an episode of postoperative low-grade fever.
Other medical conditions include frequent urinary tract infections, gastroesophageal reflux disease, and angioedema. A month ago, the patient was treated for contact dermatitis from poison ivy with a 10-day course of prednisone.
Temperature is 37.2 C (99 F), blood pressure is 130/90 mm Hg, pulse is 64/min, respirations are 14/min, and oxygen saturation is 96% on room air. The patient is drowsy but arousable with a short attention span. Pupils are small but reactive to light and accommodation. Mucous membranes are moist. The neck is supple, and cardiovascular and lung examinations are unremarkable. Abdominal examination reveals diminished bowel sounds. The patient is able to move all extremities on command, and deep tendon reflexes are symmetric. The remainder of the examination is normal.
Laboratory results are as follows:
The patient's preoperative laboratory studies were normal. Which of the following is the most appropriate next step in management of this patient?

Question

A 36-year-old woman has increasing nausea and headaches 12 hours after a right-sided percutaneous nephrolithotomy for staghorn calculi.  The procedure involved ultrasonic lithotripsy followed by fragment removal using a flexible nephroscope.  The patient spent a prolonged period in recovery and has been drowsy since returning to the ward.  She is receiving intermittent morphine for pain control.  She also received intravenous ceftriaxone after an episode of postoperative low-grade fever.
Other medical conditions include frequent urinary tract infections, gastroesophageal reflux disease, and angioedema.  A month ago, the patient was treated for contact dermatitis from poison ivy with a 10-day course of prednisone.
Temperature is 37.2 C (99 F), blood pressure is 130/90 mm Hg, pulse is 64/min, respirations are 14/min, and oxygen saturation is 96% on room air.  The patient is drowsy but arousable with a short attention span.  Pupils are small but reactive to light and accommodation.  Mucous membranes are moist.  The neck is supple, and cardiovascular and lung examinations are unremarkable.  Abdominal examination reveals diminished bowel sounds.  The patient is able to move all extremities on command, and deep tendon reflexes are symmetric.  The remainder of the examination is normal.
Laboratory results are as follows:
 The patient's preoperative laboratory studies were normal.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

11ec193a_98ff_2c69_853d_65d360a7075d_MD0002_00 This patient, who is experiencing nausea, headaches, and drowsiness following lithotripsy, has acute symptomatic hyponatremia, likely related to her recent surgery. Postoperative hyponatremia can develop within hours of surgery due to release of vasopressin related to surgical stress, the use of nonelectrolyte solutions (eg, glycine, sorbitol) for irrigation, or the infusion of hypotonic solutions during surgery. Patients with hyponatremia may be asymptomatic, or they may have mild (eg, headache, nausea, vomiting, confusion) or severe (eg, seizure, obtundation, coma) symptoms. Untreated patients may develop cerebral edema and brain herniation. Management depends on hyponatremia chronicity and associated symptoms: Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours.Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline.In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours. Patients with acute (<24-48 hours) hyponatremia who are symptomatic, such as this patient, should be treated emergently with hypertonic saline while being carefully monitored. The goal is to relieve symptoms and increase the sodium level relatively rapidly (eg, 4-6 mEq/L within the first few hours); the correction rate should not exceed 8 mEq/L in 24 hours. Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline. Regardless of hyponatremia chronicity, patients with severe symptoms and those with intracranial pathology (eg, intracranial tumor, recent traumatic brain injury) should also receive hypertonic saline. In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). In patients who do not require hypertonic saline, including most patients with chronic hyponatremia, serum sodium levels should be increased slowly; treatment depends on the underlying disease (eg, fluid restriction in hypervolemic patients, normal saline in hypovolemic patients). (Choice B) This patient needs relatively rapid correction of hyponatremia with hypertonic saline to prevent further deterioration in mental status; this cannot be achieved with an isotonic solution such as normal saline. In addition, her physical examination findings (eg, moist mucous membranes, lack of hypotension) do not suggest volume depletion. (Choice C) This patient already received ceftriaxone and does not have signs of sepsis (eg, tachycardia, hypotension) to warrant a change in antibiotics or blood cultures. Her mental status changes are more likely due to hyponatremia. (Choice D) The mechanism of the neurological manifestations of postoperative hyponatremia is unclear, but they may be due to effects of the actual irrigant used or, less commonly, to cerebral edema. In this patient, a noncontrast CT scan of the head may show cerebral edema but would not change management and could delay appropriate treatment. (Choice E) Although this patient received corticosteroids in the past, the lack of hypotension and of metabolic abnormalities consistent with adrenal insufficiency (eg, hyperkalemia, significant metabolic acidosis, hypoglycemia) makes an adrenal crisis less likely. Educational objective: Postoperative hyponatremia usually occurs due to surgical stress-related release of vasopressin, use of nonelectrolyte solutions for irrigation, or infusion of hypotonic solutions. Acute, symptomatic hyponatremia should be emergently treated with hypertonic saline. __________ References: The treatment of hyponatremia. (http://www.ncbi.nlm.nih.gov/pubmed/19523575) Postoperative hyponatremia despite near-isotonic saline infusion: a phenomenon of desalination. (http://www.ncbi.nlm.nih.gov/pubmed/8992919) Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. (http://www.ncbi.nlm.nih.gov/pubmed/24074529)

A 36-Year-Old Woman Has Increasing Nausea and Headaches 12 Hours