Effects on respiratory function of the head-down position and the complete covering of the face by drapes during insertion of the monitoring catheters in the cardiosurgical patient

BACKGROUND: We evaluated the effect on the respiratory gas exchange of the 30° head-down position and the complete covering of the face by sterile drapes. These are used to cannulate the internal jugular vein and position the pulmonary artery catheter in the cardiosurgical patient. During the two manoeuvres, 20 coronary patients and 10 patients with end-stage heart disease were supplied with oxygen (F(i)O(2) =0.4) by a Venturi mask, while 20 coronary patients breathed room air. The arterial blood samples to measure oxygen (PaO(2)) and carbon dioxide (PaCO(2)) tension and oxygen saturation (SaO(2)) were analysed by a blood gas system. RESULTS: The contemporary application of the head-down position and the drapes over the face significantly increased PaO(2) and SaO(2) in all the patientssupplied with oxygen. Without the head-down position, leaving the drapes over the face, did not significantly change the two parameters in the coronary patients supplied with oxygen, but induced a significant increase in PaO(2) and SaO(2) in the patients with end-stage heart disease. In the coronary patients that were breathing room air, PaO(2) and SaO(2) were stable throughout the study. CONCLUSIONS: We conclude that the 30° head-down position and the complete covering of the face by drapes does not interfere with respiratory gas exchange and can be safely performed in coronary patients supplied with oxygen or breathing room air and in patients with end-stage heart disease supplied with oxygen (F(i)O(2) of 0.4).