The effect of prone position on respiratory mechanics during spinal surgery.

OBJECTIVE To study the effect of prone position on respiratory mechanics during spine surgery. DESIGN Prospective study. SETTING Elective spine surgery at a university hospital. PATIENTS 12 ASA physical I & II with no coexisting cardiorespiratory disease undergoing cervical or lumbar laminectomy under general anesthesia in prone position. MEASUREMENTS Ten min after induction of general anesthesia and endotracheal intubation, while patients were in supine position, the following measurements were taken using anesthesia delivery unit (Datex Ohmeda type A_Elec, Promma, Sweden): peak airway pressure (Ppeak), peak plataeu pressure (Pplat), peak mean pressure (Pmean) and dynamic lung compliance (DLC). The same measurements were recorded 10 min after placing patients into prone position. At the end of surgery and 5 min after turning the patients supine and before tracheal extubation, the same measurements were again recorded. The results expressed as means +/- sd. One way ANOVA was used for analysis of differences in the data before, during prone position and after turning patients supine at the end of the procedure. For all comparisons p < 0.05 was considered significant. RESULTS During prone position there was significant reduction in DLC and significant increase in airway pressures. CONCLUSION We conclude that turning the patients form supine to prone position during anesthesia for spine surgery caused significant decrease of DLC and significant increase of airway pressure.