Effects of ventilatory strategy on arterial oxygenation and respiratory mechanics in overweight and obese patients undergoing posterior spine surgery

摘要

Prolonged inspiratory to expiratory (I:E) ratio ventilation may improve arterial oxygenation or gas exchange and respiratory mechanics in patients with obesity. We performed a randomised study to compare the effects of the conventional ratio ventilation (CRV) of 1:2 and the equal ratio ventilation (ERV) of 1:1 on arterial oxygenation and respiratory mechanics during spine surgery in overweight and obese patients. Fifty adult patients with a body mass index of ≥25?kg/msup2/sup were randomly allocated to receive an I:E ratio either l:2 (CRV; n?=?25) or 1:1 (ERV; n?=?25). Arterial oxygenation and respiratory mechanics were recorded in the supine position, and at 30?minutes and 90?minutes after placement in the prone position. The changes in partial arterial oxygen pressure (PaOsub2/sub) over time did not differ between the groups. The changes in partial arterial carbon dioxide pressure over time were significantly different between the two groups (P?=?0.040). The changes in mean airway pressure (Pmean) over time were significantly different between the two groups (P?=?0.044). Although ERV provided a significantly higher Pmean than CRV during surgery, the changes in PaOsub2/sub did not differ between the two groups.