Which scenario may cause respiratory alkalosis?

Which scenario may cause respiratory alkalosis?

• A. Renal failure and dehydration
• B. Excessive bicarbonate administration
• C. Anxiety and hyperventilation
• D. Airway obstruction and chest wall injury

Answer: (C)

Respiratory alkalosis occurs when ventilation increases enough to blow off CO2 faster than it’s produced, lowering arterial CO2 and raising blood pH. Anxiety often triggers rapid, deep breathing (hyperventilation), which drops CO2 levels and shifts the blood’s bicarbonate buffering toward a more alkaline state. That combination fits the scenario of anxiety with hyperventilation. The other situations don’t produce a primary respiratory alkalosis: renal failure and dehydration tend to cause metabolic disturbances, not a ventilatory-driven rise in pH. Excessive bicarbonate administration causes metabolic (not respiratory) alkalosis by increasing buffering capacity rather than lowering CO2. Airway obstruction and chest wall injury reduce ventilation, causing CO2 to build up and lead to respiratory acidosis, not alkalosis.

Respiratory alkalosis occurs when ventilation increases enough to blow off CO2 faster than it’s produced, lowering arterial CO2 and raising blood pH. Anxiety often triggers rapid, deep breathing (hyperventilation), which drops CO2 levels and shifts the blood’s bicarbonate buffering toward a more alkaline state. That combination fits the scenario of anxiety with hyperventilation.

The other situations don’t produce a primary respiratory alkalosis: renal failure and dehydration tend to cause metabolic disturbances, not a ventilatory-driven rise in pH. Excessive bicarbonate administration causes metabolic (not respiratory) alkalosis by increasing buffering capacity rather than lowering CO2. Airway obstruction and chest wall injury reduce ventilation, causing CO2 to build up and lead to respiratory acidosis, not alkalosis.