respiratory alkalosis

A 34-year-old white female goes to the funeral of her dear friend and suddenly develops chest pain, sweating and palpitations. She is rushed to an ER and an EKG is taken which is normal. On examination, she is tachycardiac and tachypneic. Her ABG shows pH of 7.48, PaCO2 of 33 mmHg, and HCO3- of 24 meq/L. Which of the following would be the most appropriate treatment of her alkalosis?

A. IV Ringer lactate.
B. IV Ammonium chloride.
C. IV Sodium bicarbonate.
D. IV Hydrochloric acid.
E. Ask the patient to breathe in a small paper bag.
F. Sedation with diazepam.

the answer is E. Ask the patient to breathe in a small paper bag.

Explanation:

This patient is experiencing a panic attack as characterized by her tachypnea, tachycardia, chest pain, sweating and palpitations in the absence of EKG abnormalities. Her ABG shows acute respiratory alkalosis (high pH with low PaCO2 and near normal bicarbonate) secondary to hyperventilation.

The treatment of respiratory alkalosis is essentially the correction of the underlying cause. Respiratory alkalosis usually occurs in response to some stimulus, so treatment is usually unsuccessful unless the stimulus is controlled. In this patient with a panic attack, the underlying cause of alkalosis is the increased respiratory rate. Therefore, the best intervention is to calm the patient and let her breathe in a closed bag (Choice E). This would expose her to a high concentration of carbon dioxide and thus reduce her respiratory drive and decrease her respiratory rate, thereby correcting the underlying cause.

Respiratory alkalosis itself is rarely life threatening; therefore, emergent treatment is usually not indicated unless the pH is greater than 7.5 (Choice A, B, D are thus incorrect).

Sedation with diazepam (Choice F) should be reserved as a next step for this patient if she does not improve with the conservative treatment.