Could hyperoxic ventilation impair oxygen delivery in septic patients?

Summary Objective: In critically ill patients, a decrease in whole body oxygen consumption under hyperoxia has been reported and this could be related to hyperoxia‐induced arterial changes. We investigated changes in brachial artery circulation and tone during short‐term hyperoxic ventilation in septic patients. Design and setting: Prospective clinical study in the intensive care unit of a university hospital. Patients: Fourteen patients (severe sepsis n = 3 and septic shock n = 11) requiring mechanically controlled ventilation due to sepsis syndrome were investigated under stable clinical conditions. Interventions: After a 20‐min period of hyperoxic ventilation (inspired oxygen fraction = 100%), two‐dimensional images of brachial artery cross‐sectional area and brachial blood flow velocities were recorded using conventional ultrasonography and pulsed Doppler simultaneously with invasive arterial pressure measurements. Measurements and main results: Hyperoxia did not affect heart rate, but increased mean arterial pressure and decreased cross‐sectional areas both at the end of diastole and at the end of systole. Haemodynamic study showed an increase in resistance index, and a decrease in distensibility and compliance coefficients. Furthermore, a decrease in brachial artery blood flow and arterial oxygen delivery was observed during hyperoxic exposure. Conclusions: Hyperoxia was paradoxically demonstrated to decrease oxygen delivery in upper limbs during septic shock.