Study Of Gastric Mucosal Perfusion During Cardiopulmonary Bypass In Infants And Children

Background:Cardiopulmonary bypass (CPB) is associated with gut mucosalhypoperfusion and hypoxia, which may contribute to gastrointestinal complications. Compromised splanchnic perfusion and the resulting gastrointestinal mucosal injury leads to a decreased mucosal barrier function, which allows translocation of intestinal flora and endotoxemia, furthermore, drives the systemic inflammatory response syndrome and multi-system organ failure. Many studies have shown that pHi measurements provide a reliable indication of the adequacy of splanchnic perfusion.lt not only can early reflect gastric mucosal oxygenation but also can early reflect global oxygenation . Monitoring gastric mucosal pressure of carbon dioxide by air gastric tonometry has been proposed to assess the adequacy of splanchnic perfusion. Currently most experts agree that the gastric-arterial CO₂ gap should be regarded as the gold standard measurement. Standard pHi is not affected by the systemic cid-base statusThere are some pattern of CPB, normothemic CPB, mild hypothermia CPB, moderate hypothermia CPB and deep hypothermic CPB etc.Objective:To evaluate the changes of gastric mucosal perfusion during CPB ofinfants and children.To compare the effects of mild hypothermia and moderate hypothermia during CPB on gastric mucosal perfusion.To discuss the relativitybetween standard pHi and arterial blood lactate during CPB. Material and methods:1. Subjects: Thirty infants and children with congenital heart disease who were performed elective operation under CPB from October 2004 to March 2005 in children's hospital of ZheJiang University were included in this study.They were divide randomly into two group A (underwent mild hypothermia CPB)and group B(underwent moderate hypothermia CPB).2. Anaesthetic management:ketamine-based anaesthesia was used in combination with midazolam and norcuron as a muscle relaxant. Anaesthesia was maintained intraoperatively with a mixture of isoflurane and intravenous fentanyl infusion.3. CPB management: Patients underwent nonpulsatile hypothermic CPB with a membrane oxygenator and hemodilution using a colloid prime. Alpha-stat management of acid-base status was used.The flow were maintained at 100¹50ml/kg. The mean perfusion pressure were maintained between 30 and 65mmHg. The HCT were maintained at 20%²5%. The nasopharyngeal temperature of group A were maintained at 33²9°C and group B were maintained at 27²4°C.4. monitor: After induction of anesthesia a Tonometric catheter was placed into the stomach and its position confirmed by aspiration of gastric contents or auscultation. Measurements of PgCCh were obtained every lOmin using air tonometry with the Tonocap monitor.Measurements were made at six time-points: lOmin after inserting tonometric catheter(Tl),10min after initiation of CPB(T2),10min after aortic cross-clamping(T3),20min after aortic cross-clamping(T4),10min after aortic declamping(T5). lOmin after the end of CPB(T6). PgCC>2,arterial blood gas and lactate were determined at all time-points. Indices of conventional hemodynamics were measured at Tl and T6. The Pg-aCCh was calculated by subtracting the temperature-corrected arterial PCO2 flom the PgCC>2. Standard pHi was calculated according to formula (pHi=7.4-logioPgC02/PaC02).5.Statistical analysis:SPSS for windows software 13.0 was applied in data statistic.Results :l.The PgCO2 and standard pHi decreased significantly (PO.05) after initiation ofCPB and then they started to increase gradually after aortic declamping . Theminimum value appeared during aortic cross-clamping.The Pg-aCC>2 increasedsignificantly (P<0.05) after initiation of CPB and then they started to decreasegradually after aortic declamping. The maximum value appeared during aorticcross-clamping.2.There was no significant difference(P>0.05)between two group in the PgCO2during CPB. There were significant difference(P<0.05) between two group in thePg-aCO2 and standard pHi after initiation of CPB.3.The arterial blood lactate increased significantly (P<...