Perioperative mucosal pH and splanchnic endotoxin concentration in orthotopic liver transplantation

Abstract

Although impairment of splanchnic perfusion may induce mucosal hypoxia and endotoxaemia during orthotopic liver transplantation (OLT), little is known about the changes in mucosal oxygenation during and after the procedure. To study the effects of liver surgery itself on mucosal pH (pHi) and the response of pHi to acute changes in portal flow, we measured gastric pHi during six liver resections using tonometry: in two patients, after clamping of the hepatoduodenal ligament, pHi decreased within 30 min and recovered promptly after reperfusion. We then investigated gastric and sigmoid pHi (pHig, pHis) during the perioperative phase in 18 OLT. Median pHi values were low before surgery (pHig 7.28 (first/third quartiles 7.22/7.34); pHis 7.27 (7.12/7.36)). Although global oxygen delivery and haemodynamic variables remained constant and veno-venous bypass (VVB) was used to maintain portal flow, pHi declined during the anhepatic phase (pHig 7.19 (7.13/7.23), P < 0.01; pHis 7.13 (7.06/7.24), P < 0.05). After reperfusion of the graft, pHi recovered and did not differ from baseline values by the end of OLT. After operation pHig increased further, reaching the highest values 30 h after ICU admission (7.34 (7.26/7.38)). In the intraoperative period, no significant endotoxaemia was observed either in portal or systemic blood. The maximum reduction in pHi was related neither to the duration of VVB and OLT nor to the number of red cell units transfused. pHi after reperfusion did not correlate with graft viability or dysfunction of the lung or kidney. We conclude that pHi indicates mucosal ischaemia during OLT which is not necessarily associated with endotoxaemia, and intraoperative pHi monitoring does not appear to be a valuable predictor of postoperative graft failure and organ dysfunction.

Gastric mucosal pH is associated with initial graft function but is not a predictor of major morbidity after liver transplantation

“…Our data confirm other reports 3,8,21 that pH a decreases during the anhepatic phase and returns to normal after reperfusion. Because gastromucosal pH is calculated using the systemic bicarbonate concentration, it is easily understood that gastromucosal pH reflects, at least partly, systemic pH in cases of metabolic acidosis.…”

“…6,7 On the other hand, impaired splanchnic tissue oxygenation has been observed during liver transplantation, even with the use of venovenous bypass, although no deleterious effect on outcome could be detected. 8 During liver transplantation, shifts in arterial pH are well known. 9 So far, it has remained unclear whether the measured pH i should be corrected for arterial pH, but in case of a systemic disturbance in acid-base balance, the use of a corrected pH i (standard pH i ) is recommended.…”

Markers of cellular dysoxia during orthotopic liver transplantation in pigs

“…In this context, although gastric tonometry appeared to have a low capability of identifying splanchnic dysoxia in this experiment, our data do not discredit tonometry as a marker of splanchnic hypoperfusion. In humans, Welte et al documented decreased values of gastric pHi during the anhepatic phase, possibly reflecting gastric mucosal ischemia associated with liver transplantation [30]. However, they failed to document any association between gastric pHi and the development of graft failure or organ dysfunction [30].…”

“…In humans, Welte et al documented decreased values of gastric pHi during the anhepatic phase, possibly reflecting gastric mucosal ischemia associated with liver transplantation [30]. However, they failed to document any association between gastric pHi and the development of graft failure or organ dysfunction [30].…”

Basolateral potassium (IKCa) channel inhibition prevents increased colonic permeability induced by chemical hypoxia

“…These complications increase postoperative mortality and may also reduce longterm survival (19,33,45). Impaired intestinal perfusion, gut barrier failure, and increased bacterial translocation are recognized events following liver resection in humans and animals (10,16,25,26,39,42,46). Intestinal ischemia has therefore been proposed as the key event underlying increased mucosal permeability and bacterial translocation, resulting in sepsis and multiorgan failure (36).…”