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

The contemporary application of the head-down position and the drapes over the face significantly increased PaO2 and SaO2 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 PaO2 and SaO2 in the patients with end-stage heart disease. In the coronary patients that were breathing room air, PaO2 and SaO2 were stable throughout the study.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 (FiO2 of 0.4).The complete covering of the face by sterile drapes is a manoeuvre routinely used to cannulate the internal jugular vein and position the pulmonary artery catheter. The head-down position is a manoeuvre associated with that of sterile drapes when particular conditions (big and short neck, hypovolemia) make the cannulation of the jugular vein difficult [1]. Experimental and clinical studies have shown that the head-down position can interfere with respiratory function by reducing the functional residual capacity (FRC) and increasing the pulmonary blood volume [2,3,4]. A literature search found no data supporting a negative effect on respiratory function with the drapes covering the face; however, we hypothesized such a negative influence, supposing that the application of the sterile drapes over the face can favour the rebreathing of the expired gases. The aim of this study was to evaluate the effect on respiratory gas exchange of the two combined manoeuvres used during the insertion of monitoring catheters in the cardiosurgical patient before induction of anaesthesia.Fifty-four patients scheduled for elective coronary bypass grafting (CABG; 43 c