Discussion
bleeding, blood loss, intraoperative blood loss, cardiovascular and coagulation, lesser intraoperative blood loss
BLOOD LOSS, BLEEDING, SURGICAL BLOOD LOSS, INTRAOPERATIVE BLOOD LOSS
This study was done to investigate the effect of mechanical ventilation mode on the outcomes in patients undergoing PLIF in prone position. As main outcomes, amount of intraoperative surgical bleeding, transfusion requirement, and surgeon satisfaction were compared in two groups of VCV and PCV. Hemodynamic parameters, heart rate, and blood pressure were also measured and compared in the two groups as other outcomes.PCV group showed slightly better outcomes than VCV group in terms of mean blood loss (431 cc vs. 465 cc), transfusion requirement (0.40 vs. 0.43 unit), and satisfaction of the surgeon from surgical field (82.1% vs. 74.4%); however, the differences were not statistically significant.Zhendan Peng et al. after a similar randomized controlled trial reported a similar result of less, but not significant blood loss in PCV group [However, there are some studies in which PCV has been reported to be significantly associated with lesser intraoperative blood loss [To explain the inconsistency of our results with studies that demonstrated significant lesser surgical bleeding during PCV, other factors influencing intraoperative blood loss should be considered. For example, age is an important factor that affects cardiovascular and coagulation status. The mean age of patients in our study was 42–44 years, while the patients in Kang et al. study aged more than 64 years in average. Moreover, all patients in our study were operated in prone position, whereas in some studies the patient’s position during the surgery had been different. Length of surgery and number of surgical levels are among other factors that were different in our study and can explain our different results regarding surgical blood loss. In our study, there were 11 patients with 4 fused levels in VCV group comparing 3 patients in PCV group. Although not significant and by chance, this may have a negative effect on blood loss.In our study, diastolic blood pressures 90 and 105 min. after induction were significantly lower in PCV group (Some authors believe that because of hemodynamic stability and providing lower PIP, PCV is a better choice than VCV for patients undergoing lumbar spine fusion surgery [