Quantifying the Amount of Bleeding and Associated Changes in Intra-Abdominal Pressure and Mean Airway Pressure in Patients Undergoing Lumbar Fixation Surgeries: A Comparison of Three Positioning Systems

Abstract

Study DesignProspective, randomised controlled, single centre study of 45 patients posted for two level lumbar fixation surgery in the prone position.PurposeTo compare intra-abdominal pressure (IAP), mean airway pressure mean airway pressure and blood loss during the spine surgery in prone position using three different positioning systems.Overview of LiteratureStudies have correlated IAP with the amount of perioperative bleeding. However, IAP and airway pressures while assessing the bleeding comparing two or more prone positioning systems are unclear.MethodsThis prospective study was conducted on a cohort of 45 patients scheduled for two-level lumbar fixation. Patients were randomly allocated to a spine table, Wilson's frame, and thermomodulated pads. Bladder pressure as an indicator of IAP, mean and peak airway pressures, and blood loss were monitored.ResultsIAP increased whenever patient position was changed to prone .The increase in pressure was more in the Wilson's frame group but was statistically significant only on prolonged positioning. Adopting the prone position always increased the mean airway pressure, but the increased was significant only in the Wilson's frame group. Mean airway pressure decreased in the spine table group and was statistically significant. The blood loss in the spine table group was significantly less as compared to the other groups.ConclusionsPositioning on a spine table results in less blood loss and low mean airway pressure. The Wilson's frame results in high IAP, increased mean airway pressure, and more blood loss. The thermomodulated frame increases mean airway pressure and produces a moderate increase in IAP and airway pressure.

A Comparative Evaluation of the Effect of Prone Positioning Methods on Blood Loss and Intra-Abdominal Pressure in Obese Patients Undergoing Spinal Surgery

“…12 The method chosen to measure IAP has been devised by Kron et al and later standardized and validated by Fusco et al 8,13 This method is noninvasive, accurate, and the most commonly method used for measuring IAP. 7 The mean baseline IAP recorded in the present study in supine position was within the normal range of 4 to 8 cm Hg described by Sanchez et al 14 but slightly higher than that reported by Park and Malhotra et al 2,7 This could be due to the fact that both these studies were conducted on patients with normal BMI, whereas the present study enrolled only obese patients. Obese patients tend to have higher baseline IAP and the direct correlation between IAP and BMI has been previously reported by Wilson et al 15 The increase in mean IAP in both groups on placing the patients in prone position is on the expected lines as IAP tends to increase on placing the patients prone.…”

“…16 Malhotra et al had also reported that Wilson's frame is associated with greater IAP as compared to spinal table and thermo-regulated pads, which were the other alternative frames available in their set up. 7 The HR and MAP were statistically similar in both groups at all time intervals. This finding is important because prone position often results in reduction of stroke volume and cardiac index thus predisposing patients to hypotension.…”

“…Most of the studies conducted to evaluate the effect of prone positioning systems on IAP have been conducted on patients with normal BMI. 4,6,7 The results of such studies, however, may not be valid for obese patients. The only study to evaluate the effect of BMI on IAP was conducted by Han et al, who reported that IAP increases to a greater extent when patients with increased BMI are positioned prone.…”

Cushing Syndrome: A Potential Risk of Bilateral Postoperative Ischemic Optic Neuropathy after Lumbar Fusion

“…BMI was reported to influence intraabdominal pressure in the prone position more than in the supine position during lumbar spinal surgery. A positive correlation of blood loss and intraabdominal pressure and with BMI in the prone position was reported 1015). Intraocular pressure also rises if there is direct pressure on the abdomen 8).…”

Equal Ratio Ventilation Reduces Blood Loss During Posterior Lumbar Interbody Fusion Surgery

“… 9 – 11 All of these hemodynamic and respiratory changes in the prone position may cause engorgement of the vertebral veins and increase in surgical bleeding. 8 …”