Hyperoxia-induced arterial compliance decrease in healthy man.

INTRODUCTION

Oxygen therapy is commonly used in emergency department and intensive care units without careful evaluation of its effects, especially on the haemodynamics and artery characteristics.

MATERIALS AND METHODS

A prospective laboratory study evaluated brachial circulatory effects of normobaric hyperoxia using ultrasonography-Doppler. The study was set in a hospital research laboratory. The subjects were thirteen healthy volunteers. Investigations were performed under normal air ventilation and after 20 min of hyperoxic mixture ventilation using a high concentration mask. Two dimensional images and brachial blood flow velocities were recorded using ultrasonography and pulsed Doppler to study changes in cross sectional area, blood flow, resistance index, and cross-sectional compliance coefficient.

RESULTS

During hyperoxic exposure, mean PaO2 was 372 +/- 21 mmHg. A significant decrease of heart rate was observed. Arterial pressures (systolic and diastolic arterial pressures) were not modified. A decrease of cross sectional areas at end diastole and end systole was observed. Pulsed Doppler study showed a decrease of brachial artery blood flow and an increase of the resistance index. Furthermore, a decrease of the cross-sectional compliance coefficient was observed during hyperoxic exposure in all subjects.

CONCLUSION

This study using two-dimensional ultrasonography and pulsed Doppler could demonstrate an increase in brachial arterial tone and a decrease in brachial blood flow under normobaric hyperoxia.