Peritoneal ventilation in volume controlled hemorrhagic shock: outcome model in rats

Introduction

Peritoneal ventilation was studied few years ago [1,2] to be a successful auxiliary extrapulmonary method for improving oxygenation and CO₂ elimination in laboratory animals with experimental ARDS. Bowel ischemia during hemorrhagic shock is known to cause, after initial fluid resuscitation, late hazardous remote effects with multiple organ system failure and high mortality rate [3].

Hypothesis

In severe volume controlled hemorrhagic shock, peritoneal ventilation with oxygen would: 1) improve local oxygenation of the abdominal viscera, preventing later multiple organ failure, and 2) increase survival rate.

Methods

(Figure) The study included three groups (10 rats each), using light anesthesia (N₂O/O₂ and Halothane) during preparation and the first 120 min of the study. Group I = PEV-O₂ (Peritoneal ventilation with 100% oxygen), Group II = PEV-RA (PEV with room-air), Group III (control, no PEV). In groups I & II, a 14 F catheter was surgically introduced into the peritoneal cavity, before hemorrhagic shock (HS). Phase I - HS: All rats underwent blood withdrawal of 3 ml/100 g body weight within 15 min, causing HS lasting up to 60 min. Starting at 15 min, Group I & II were terated by peritoneal ventilation (oxygen vs. room-air), rate = 40/min, tidal volume = 6 ml, until the end of resuscitation phase. Phase II - Resuscitation - lasted 60 min (from 60 to 120 min), at the beginning of which 3-4 ml of blood transfusion increased MAP to >80 mmHg within 2-3 min. The rest of the blood was transfused over the next 15 min. Phase III - observation - lasted 7 days. Surviving rats were scarified (high dose halothane). Necropsy of abdominal organs was performed in all rats.

Results

Survival to 7 days was achieved by 10 of 10 rats in PEV-O₂ Group I, 9 of 10 in PEV-RA Group II, and 5 of 10 rats in the Control Group III. Survival rate in the PEV-O₂ group (100% survival) was significantly higher than that of the control group, but not significantly higher than that of the PEV-RA group. The survival rate of the PEV-RA group (90%) was not significantly higher than that of the control group (50%). Morbidity evaluation of all rats during the observation phase, as reflected by their daily neurological deficit scores, showed significant difference between all groups. Necropsy examination of the rats who died during the observation phase showed marked, diffuse pathology of abdominal organs, mainly gut perforations and necrosis. Necropsy of the rats who survived the 7 days of observation, showed marked macroscopic abnormalities in all survivors of the Control Group III, moderate changes in most of the rats of the PEV-RA Group II, and normal examination in all 10 rats of the PEV-O₂ Group I.

Conclusion

Peritoneal ventilation with oxygen during and after hemorrhagic shock, seems to help to preserve viability of the intestine and may significantly decrease morbidity and mortality.

Figure.

Peritoneal ventilation: study design.