A 21-year-old man is brought to the emergency department after being found unresponsive in a public restroom. He has a history of injection drug use. Temperature is 36.1 C (97 F), blood pressure is 110/70 mm Hg, pulse is 62/min, and respiratory rate is 8/min. On physical examination, the patient is unconscious with pinpoint pupils. Endotracheal intubation is performed, and mechanical ventilation is begun. The ventilator settings are adjusted to provide a minute ventilation of 6.0 L/min. Calculated alveolar ventilation is 4.2 L/min. Which of the following most likely accounts for the difference between these 2 parameters?

Question

A 21-year-old man is brought to the emergency department after being found unresponsive in a public restroom.  He has a history of injection drug use.  Temperature is 36.1 C (97 F), blood pressure is 110/70 mm Hg, pulse is 62/min, and respiratory rate is 8/min.  On physical examination, the patient is unconscious with pinpoint pupils.  Endotracheal intubation is performed, and mechanical ventilation is begun.  The ventilator settings are adjusted to provide a minute ventilation of 6.0 L/min.  Calculated alveolar ventilation is 4.2 L/min.  Which of the following most likely accounts for the difference between these 2 parameters?

Quizplus · Accepted Answer

Eductional Objective: Minute ventilation is equal to the product of tidal volume and respiratory rate and includes dead space ventilation.  Alveolar ventilation is equal to the product of respiratory rate and the difference between tidal volume and dead space volume.

A 21-Year-Old Man Is Brought to the Emergency Department After