Effect of Trendelenburg position during prone ventilation in fifteen COVID-19 patients. Observational study

Background Prone position ventilation has shown to improve oxygenation and mortality in severe ARDS. The data of prone position ventilation during severe ARDS secondary to COVID-19 have shown similar benefit in oxygenation and mortality. Usually, patient placed in prone position are placed flat or in reverse Trendelenburg positioning to decrease risk of aspiration and abdominal girth compressing the chest. To date, no studies are available to compare the effects of positioning the bed in different angles during the prone position ventilation. Methods An observational study in fifteen patients with severe ARDS secondary to COVID-19 who were placed in the prone position for the first time. All the patients were sedated and chemically paralyzed with no spontaneous effort. All patients were ventilated with the pressure-controlled mode with set PEEP according to the pressure-volume curves. Five patients had esophageal balloon manometry to estimate pleural pressures and trans-pulmonary pressures. Patients were initially placed in reverse Trendelenburg position and later in Trendelenburg position. Tidal volume and respiratory compliance were observed for 30 minutes after bed positioning has been achieved. Tidal volume and total respiratory compliance in both Trendelenburg and reverse Trendelenburg position were compared. Ventilator settings were not changed during the observation. No patients were suspected of increased intra-cranial or intra-ocular pressures. T-test was done to compare the values. Results Tidal volume significantly increased by 80.26 ± 23.4 ml/breath (95% CI 37.7 - 122.9) from 391.3 ± 52.7 to 471.6 ± 60.9 (20.5%) P 0.001. The respiratory system compliance significantly increased by 4.9 ml/cmH2O (95% CI 1.4 - 8.4) from 34.6 ± 4.7 to 39.5 ± 4.6 (14%) P 0.001. Of the five patients with esophageal balloon, the lung compliance significantly increased by 16.7 ml/cmH2O (95% CI 12.8 – 20.6) from 66.6 ± 1.7 to 83.3 ± 3.3 (25%) P 0.001. The chest wall compliance had small but non-significant increase by 1.5 ml/cmH2O (95% CI -1.3 – 4.3) from 65 ± 1.4 to 66.5 ± 2.3 (2%) P 0.085. Conclusion In this study, statistically significant increase in tidal volume, lung and respiratory system compliance were observed in patients placed in the Trendelenburg position during prone position ventilation. The results reflect the effect of body positioning during prone position ventilation. These effects may be the reflection of altered ventilation distribution throughout the lungs and change in pleural pressure as well as trans-pulmonary pressure during body positioning. More studies need to be done to confirm and examine this phenomenon. Precautions should be taken as this maneuver can increase the intra-cranial and intra-ocular pressures. Keywords: COVID-19, Trendelenburg, Reverse Trendelenburg, ARDS

Successive perioperative management of laparoscopic liver resection in the reverse Trendelenburg position for a patient with Fontan physiology: a case report

Background Laparoscopic surgery for a patient with Fontan physiology is challenging because pneumoperitoneum and positive pressure ventilation could decrease venous return and the accumulated partial pressure of arterial carbon dioxide (PaCO2) could increase pulmonary vascular resistance, which might lead to disruption of the hemodynamics. Case presentation A 25-year-old man with Fontan physiology was scheduled to undergo laparoscopic liver resection for Fontan-associated liver disease (FALD) with noninvasive monitoring of cardiac output (CO) by transpulmonary thermodilution in addition to transesophageal echocardiography. The abdominal air pressure was maintained low, and we planned to switch to open abdominal surgery promptly if hemodynamic instability became apparent because of the accumulated PaCO2 or postural change. Consequently, the pneumoperitoneum had limited influence on circulatory dynamics, but central venous pressure significantly decreased with postural change to the reverse Trendelenburg position. Laparoscopic liver resection for FALD was performed successfully with no significant changes in CO and central venous saturation. Conclusions With strict circulation management, laparoscopic surgery for a patient with Fontan physiology can be performed safely. Comprehensive hemodynamic assessment by noninvasive transpulmonary thermodilution can provide valuable information to determine the time for shift to open abdominal surgery.

Effect of Body Posture on Lung Ventilation and Oxygenation During Carbon Dioxide Pneumoperitoneum in Rabbit

This study was conducted to investigate the influence of body position on respiratory compliance and oxygenation during iatrogenic pneumoperitoneum in the rabbit. The peak inspiratory pressure, dynamic compliance, static compliance and arterial gas parameters were calculated and measured 10 min before and 30 min after the creation of pneumoperitoneum with the patient in the horizontal position, 30 min after placing the patient in the Trendelenburg position and 30 min after placing the patient in the reversed Trendelenburg position. Following the creation of pneumoperitoneum and Trendelenburg positioning, there was a significant increase in peak inspiratory pressure while dynamic and static respiratory compliance decreased. Similarly, arterial oxygenation increased during Trendelenburg position while arterial carbon pressure remained within limits during all positions. Overall, the reverse Trendelenburg position did not improve ventilation, neither the oxygenation. However, this position showed to be more appropriate because may reduce the risk of lung injury associated with high-pressure ventilation during pneumoperitoneum.

Optimum Degree of Head Elevation/Reverse Trendelenburg Position for Sinus Surgery: Systematic Review

Background This review aims to evaluate the effect of Reverse Trendelenburg Position (RTP) on bleeding and Boezaart score and to determine the optimum degree of head elevation through a systematic review and meta-analysis. Methodology: We conducted a systematic review according to PRISMA guidelines and a literature search was performed on PubMed, Web of Science, Cochrane, Dental and Oral Science, Google scholar and Clinicaltrials.gov and included randomized controlled trials (RCTs) in English language only. We extracted all relevant data and conducted quality assessment using Cochrane risk of Bias tool (Version 2). We also performed quality assessment of the outcomes using GRADE. Meta-analysis for all the outcomes using conducted on RevMan version 5.3. Results The search identified 629 articles and three RCTs that met our inclusion criteria. Two were included in the meta-analysis. A total of 124 patients were assessed for bleeding during sinus surgery and there was a significant reduction in total blood loss in RTP (10–15°) when compared to horizontal position by 134 ml (Mean Difference (MD): −134.23; 95% confidence interval (CI): −184.13 to −67.27). RTP also had a significant reduction in bleeding per minute by 1.07 ml/min (MD: −1.07; 95%CI: (−1.69 to −0.44), while the Boezaart score was significantly lower in the RTP group (MD: −0.69; 95%CI: −0.94 to −0.43) when compared to horizontal position. Conclusion Though with limited evidence RTP for ESS reduces total blood loss, blood loss per minute and improves visualization. Further studies are needed to assess the actual impact and optimal degree of head elevation.