Question

A 40-year-old man with a history of IV drug use presents with cellulitis with multiple abscesses of the right upper extremity. His current weight is 70 kg (lean body weight). He rapidly develops worsening respiratory distress and hypotension and ultimately requires intubation and mechanical ventilation. Blood gas analysis shows a pH of 7.23, Paco2 of 58 torr, Pao2 of 60 torr, and an oxygen saturation of 88%. His ventila- tor settings are assist-control mode with a tidal vol- ume of 420 mL, respiratory rate of 16 breaths/min,positive end-expiratory pressure (PEEP) of 5 cm H2O, and Fio2 of 70%. His plateau pressure on the ventilator is 29 cm H2O. A chest radiograph shows bilateral interstitial infiltrates, and a 2-dimensional echocardiogram demonstrates normal left ventricular function. What ventilator adjustments should be made?

(A) Change the ventilator mode to synchronized intermittent mandatory ventilation
(B) Increase PEEP
(C) Increase respiratory rate to 24 breaths/min (D) Increase tidal volume to 600 mL
(E) Leave the ventilator settings unchanged

Answer 1

Increasing PEEP would likely be the most appropriate ventilator adjustment for the patient to improve oxygenation, considering his normal plateau pressure and the signs of hypoxemic respiratory failure present.

Step-by-step explanation:

The 40-year-old man in question is showing signs of hypoxemic respiratory failure, which is evident from the blood gas analysis. His challenge is to improve oxygenation while minimizing any potential ventilator-induced lung injury. The blood gas shows a low pH indicating acidosis, a high Paco2, which reflects hypoventilation, a low Pao2, indicating hypoxemia, and a reduced oxygen saturation. Given that his plateau pressure is acceptable (29 cm H2O) but oxygenation is poor, increasing the PEEP can help improve oxygenation by keeping the alveoli open and thus improving gas exchange. The goal is to improve alveolar ventilation without causing overdistension or barotrauma. Therefore, the best adjustment to the ventilator settings would be to increase PEEP (B), rather than changing the mode of ventilation, increasing tidal volume, or respiratory rate unnecessarily or keeping the settings unchanged.