Question 1

An increase in the H⁺ ion concentration [H⁺] of the blood due only to an increase in the arterial PCO₂ (hypercapnia) best describes which of the following?

Accepted Answer

An increase in the arterial PCO2 (hypercapnia) will lead to an increase in carbonic acid (H2CO3) formation, which dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). This increase in hydrogen ion concentration will lower blood pH, leading to respiratory acidosis. This does not involve changes in metabolic processes, so metabolic acidosis or alkalosis is not a correct choice, and the term "ion concentration" rules out respiratory alkalosis.

Question 2

A patient has a pH of 7.49. What would this define?

Accepted Answer

A pH of 7.49 is higher than the normal pH range of 7.35-7.45, indicating alkalosis.

Question 3

In the face of uncompensated respiratory acidosis, which of the following blood gas abnormalities would you expect to encounter? I.decreased pH II.increased HCO₃^- III.increased PCO₂ IV.increased pH

Accepted Answer

In uncompensated respiratory acidosis, you would expect to see a decreased pH due to the accumulation of CO2, which forms carbonic acid in the body, lowering the pH. Increased PCO2 is also expected as the primary issue in respiratory acidosis is the accumulation of CO2 due to inadequate ventilation. HCO3- may eventually increase as a compensatory mechanism, but in the uncompensated phase, the focus is on the direct consequences of retained CO2. An increased pH would not be expected in the context of acidosis.

Question 4

Correction of acute respiratory acidosis is accomplished by which of the following?

Accepted Answer

Acute respiratory acidosis occurs due to hypoventilation, resulting in an increase in carbon dioxide (CO2) levels and a decrease in pH. The best way to correct it is by increasing alveolar ventilation, which causes the elimination of CO2 and a decrease in carbonic acid levels, thereby increasing pH. Other choices, such as increasing or decreasing HCO₃F1F1F1S1^F1F1F10 reabsorption, are not relevant to the correction of respiratory acidosis.

Question 5

Compensation for metabolic acidosis occurs through which of the following?

Accepted Answer

Compensation for metabolic acidosis involves hyperventilation, which decreases blood CO2 levels, thereby reducing acidity and helping to restore normal pH.

Question 6

Compensation for respiratory acidosis occurs through which of the following?

Accepted Answer

Compensation for respiratory acidosis involves an increase in blood bicarbonate (HCO3-) levels to help neutralize the excess acid.

Question 7

Which of the following accurately describes compensation for acid-base disorders?

Accepted Answer

Compensation for respiratory disorders occurs through the kidneys, which cannot make immediate changes to pH levels. It can take hours to days for the kidneys to adjust pH levels in response to respiratory acid-base disorders. Therefore, the statement "Kidneys take hours to days to compensate for respiratory disorders" is accurate. The other choices are not entirely correct, as compensation for metabolic disorders involves the lungs (not the kidneys); renal compensation is not always complete, and respiratory compensation may also not be complete in some cases.

Question 8

A patient has a bicarbonate concentration of 36 mEq and a PCO₂ of 60 mm Hg. What is the approximate pH?

Accepted Answer

The patient's bicarbonate concentration and PCO2 suggest a compensated respiratory acidosis or metabolic alkalosis. Using the Henderson-Hasselbalch equation, pH = 6.1 + log([HCO3-]/(0.03*PCO2)), substituting the given values, the pH is closer to 7.4, indicating a normal or slightly altered pH due to compensation mechanisms.

Question 9

What is a normal response of the body to a failure in one component of the acid-base regulatory mechanism?

Accepted Answer

The normal response of the body to a failure in one component of the acid-base regulatory mechanism is compensation, where other components try to maintain homeostasis by adjusting pH levels through the respiratory or renal system. Autoregulation and correction are not physiological responses, but rather refer to processes of regulation and adjustment. Homeostasis is a general concept of maintaining stable internal conditions, but does not describe the specific response to a failure in acid-base regulation.

Question 10

Causes of respiratory acidosis in patients with normal lungs include which of the following?
I.neuromuscular disorders
II.spinal cord trauma
III.anesthesia
IV.central nervous system depression

Accepted Answer

All of the options listed can lead to respiratory acidosis in patients with normal lungs. Neuromuscular disorders can affect the ability to effectively breathe, spinal cord trauma can impair respiratory muscles or the brainstem control of breathing, anesthesia can depress respiratory drive, and central nervous system depression can also impair respiratory drive.

Question 11

A patient with a measured plasma HCO₃^- concentration of 24 mmol/L has an episode of acute hypoventilation, with the PCO₂ rising from 40 to 70 mm Hg. What do you predict will happen acutely to the plasma HCO₃^-concentration?

Accepted Answer

The increase in PCO₂ will cause a shift in the Haldane effect, decreasing the affinity of hemoglobin for CO2 and increasing CO2 concentration in the plasma. This will lead to an increase in HCO₃F1F1F1S1^F1F1F10 concentration to maintain equilibrium between the plasma and alveolar CO2. The expected rise in HCO₃F1F1F1S1^F1F1F10 concentration is about 27 to 28 mmol/L.

Question 12

A decrease in the H⁺ ion concentration [H⁺] of the blood caused by a low PaCO₂ best describes which of the following?

Accepted Answer

Respiratory alkalosis occurs when there is a decrease in carbon dioxide (PaCO2) in the blood, which can lead to a decrease in hydrogen ion concentration, making the blood more alkaline.

Question 13

An ABG result shows pH of 7.35, PaCO₂ of 30 mm Hg, and HCO₃^- of 18 mEq/L. What compensatory measure has the body taken to at least partially compensate for the acid-base disorder?

Accepted Answer

The pH is low (acidotic) and the PaCO2 is also low, indicating respiratory alkalosis. The body has compensated by blowing off CO2 through hyperventilation, which would decrease the PaCO2.

Question 14

What is the most common cause of respiratory alkalosis?

Accepted Answer

The answer of What is the most common cause of...

Question 15

Which of the following clinical findings would you expect in a fully compensated respiratory acidosis? I.elevated HCO₃^- II.pH below 7.35 III.pH between 7.35 and 7.39 IV.elevated PO₂

Accepted Answer

In fully compensated respiratory acidosis, the kidneys retain bicarbonate (HCO3-) to compensate, leading to elevated HCO3-. The pH is brought back towards normal, typically between 7.35 and 7.39. Elevated PO2 is not a typical finding.

Question 16

An ABG result shows the pH to be 7.56 and the HCO₃^- to be 23 mEq/L. Which of the following is the most likely disorder?

Accepted Answer

The ABG result shows a high pH (7.56), indicating alkalosis, and a normal or slightly low HCO3- (23 mEq/L), suggesting the primary problem is not metabolic. Therefore, the most likely disorder is respiratory alkalosis, which is characterized by an elevated pH due to decreased CO2 levels from hyperventilation.

Question 17

What is the primary chemical event in metabolic alkalosis?

Accepted Answer

The primary chemical event in metabolic alkalosis is an increase in blood bicarbonate (HCO3-) levels.

Question 18

An ABG result shows pH of 7.35, PaCO₂ of 30 mm Hg, and HCO₃^-of 18 mEq/L. Which of the following is the patient's most likely primary disorder?

Accepted Answer

The ABG results show a pH within normal limits, a decreased PaCO2 (indicating hyperventilation or respiratory alkalosis), and a decreased HCO3- (indicating a primary metabolic acidosis). The primary disorder is metabolic acidosis because the primary change is in the bicarbonate level (HCO3-), which is decreased.

Question 19

What is the primary chemical event in respiratory acidosis?

Accepted Answer

The primary chemical event in respiratory acidosis is an increase in blood CO2 levels, as it leads to a decrease in blood pH.

Question 20

Which of the following are potential causes of respiratory alkalosis?
I.anxiety
II.central nervous system depression
III.hypoxemia
IV.pain

Accepted Answer

Respiratory alkalosis occurs when there is a decrease in carbon dioxide levels in the blood, often due to hyperventilation. Anxiety and pain can lead to hyperventilation, increasing the rate and depth of breathing, thus causing respiratory alkalosis. Hypoxemia, or low oxygen levels in the blood, can also stimulate hyperventilation as the body attempts to increase oxygen intake, contributing to respiratory alkalosis. Central nervous system depression, however, typically leads to respiratory depression, not alkalosis, making choices I, III, and IV correct.

Quiz 13: Acid-Base Balance

An increase in the H+ ion concentration [H+] of the blood due only to an increase in the arterial PCO2 (hypercapnia) best describes which of the following?

A patient has a pH of 7.49. What would this define?

In the face of uncompensated respiratory acidosis, which of the following blood gas abnormalities would you expect to encounter? I.decreased pH II.increased HCO3- III.increased PCO2 IV.increased pH

Correction of acute respiratory acidosis is accomplished by which of the following?

Compensation for metabolic acidosis occurs through which of the following?

Compensation for respiratory acidosis occurs through which of the following?

Which of the following accurately describes compensation for acid-base disorders?

A patient has a bicarbonate concentration of 36 mEq and a PCO2 of 60 mm Hg. What is the approximate pH?

What is a normal response of the body to a failure in one component of the acid-base regulatory mechanism?

Causes of respiratory acidosis in patients with normal lungs include which of the following? I.neuromuscular disorders II.spinal cord trauma III.anesthesia IV.central nervous system depression

A patient with a measured plasma HCO3- concentration of 24 mmol/L has an episode of acute hypoventilation, with the PCO2 rising from 40 to 70 mm Hg. What do you predict will happen acutely to the plasma HCO3- concentration?

A decrease in the H+ ion concentration [H+] of the blood caused by a low PaCO2 best describes which of the following?

An ABG result shows pH of 7.35, PaCO2 of 30 mm Hg, and HCO3- of 18 mEq/L. What compensatory measure has the body taken to at least partially compensate for the acid-base disorder?