Could hyperoxic ventilation impair oxygen delivery in septic patients?

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.