Gastric intramucosal pH and hepatic venous oximetry after cardiopulmonary bypass in valve replacement patients

Correlation of hepatic venous saturation and mixed venous saturation: pooled analyses

INTRODUCTION

In critical care, monitoring adequate tissue oxygenation is essential. Mixed venous oxygen saturation has traditionally been considered the gold standard for measuring cardiac output, which represents systemic oxygen delivery. Studies have shown that hepatic vein saturation is correlated with mixed venous oxygen saturation and mortality. The primary aim of this study was to determine the correlation between hepatic vein saturation and mixed venous saturation, and the impact of clinical characteristics on this correlation.

EVIDENCE ACQUISITION

A systematic review of the literature was performed to identify manuscripts. They must have included patients who received simultaneous mixed venous saturations and hepatic vein saturations, and the data for both must have been explicitly shared. Data were pooled from these studies to analyze the correlation between mixed venous saturation and the corresponding hepatic vein saturation.

EVIDENCE SYNTHESIS

A total of 13 studies with 333 patients were included in the final analyses. The average age across these studies was 60.3±5.2. The pooled correlation between the mixed venous saturation and hepatic vein saturation was 0.88, demonstrating a strong correlation between the two. The average mixed venous saturation was 73.3±5.0 while the average hepatic vein saturation was 59.5±11.1.

CONCLUSIONS

In these pooled analyses, hepatic vein saturation has a strong correlation with mixed venous saturation. This correlation is not significantly impacted by patient age, weight, or clinical setting. Nonetheless, further prospective studies are needed for confirmation.

High dose statin prophylaxis in cardiopulmonary bypass related surgery: clinical utility

Background

Previous studies from our group demonstrated the anti-inflammatory properties of statins on cardiopulmonary bypass (CPB), through inhibition of neutrophil transendothelial migration. We sought to determine the utility of preoperative statin on patients undergoing cardiac surgery, to investigate any moderating effects on the systemic inflammatory response (SIRS) with CPB, and to evaluate any clinical impact on our patients.

Methods

This is a prospective, randomised controlled trial with national regulatory body approval. Eligible patients were already on oral statin therapy. They were then randomly assigned to either investigation arm (n = 15, atorvastatin 80 mg for 2 weeks before surgery) or control arm (n = 15, no change to current statin therapy). Blood and urine samples were collected at 3 timepoints. Postoperative clinical measures were documented.

Results

Patients in the investigation arm have significantly lower troponin level (p = 0.016), and lower level of urine neutrophil gelatinase-associated lipocalin (NGAL; p = 0.002); thus demonstrating a lesser degree of cardiac and renal injury in these patients. Higher level of Interleukin-8 (IL-8) at baseline (p = 0.036) and 4 h post cross-clamp removal (p = 0.035) in the investiation arm. A similar trend is also observed in Matrix Metalloproteinase-9 (MMP-9; p > 0.05). There were however no differences in clinical outcomes.

Conclusions

Maximizing the dose of statin in patients waiting for cardiac surgery has measurable biological effects. There is evidence of less cardiac and renal damage. The use of preoperative statins and in particular, high dose preoperative statin therapy, may prove a useful new tool for optimal preparation of patients for cardiac surgery.

Trial registration

EudraCT no. 2012-003396-20. Registered 05 November 2012

The effect of nicorandil on small intestinal ischemia-reperfusion injury in a canine model

BACKGROUND

It has been shown that nicorandil, which has both ATP-sensitive K+ (KATP) channel opener-like and nitrate-like properties, has an organ-protective effect in ischemia-reperfusion injury in several experimental animal models.

AIMS

We evaluate the effectiveness of nicorandil on warm ischemia-reperfusion injury of the small intestine in a canine model.

METHODS

Eighteen beagle dogs were divided into three groups: the control group (n=6); the nicorandil group (n=6), to which nicorandil was injected intravenously before the ischemia; and the glibenclamide group (n=6), to which glibenclamide, which closes the KATP channel and does not suppress the nitrate effect of nicorandil, was orally administered, and then nicorandil was injected in the same manner as in the nicorandil group. Both the superior mesenteric artery and vein were clamped for 2 h. Superior mesenteric artery blood flow, small intestinal mucosal tissue blood flow, intramucosal pH, and histopathological analyses were compared among the three groups.

RESULTS

Superior mesenteric artery blood flow, mucosal tissue blood flow and pHi after reperfusion were significantly maintained in the nicorandil in comparison with the control and the glibenclamide groups. The histopathological findings showed less severe mucosal damage after reperfusion in the nicorandil group compared with the other two groups. Between the control group and the glibenclamide group, no significant differences were observed in all those parameters.

CONCLUSION

This study suggests that nicorandil has a protective effect on small intestinal IR injury, and activation of KATP channels plays an important role in inhibiting small intestinal IR injury.

Effects of Sevoflurane on Biomechanical Markers of Hepatic and Renal Dysfunction After Coronary Artery Surgery

OBJECTIVE

The purpose of this study was to compare the effects of a total intravenous and a volatile anesthetic regimen on biochemical markers of hepatic and renal dysfunction after coronary artery surgery.

DESIGN

Prospective, double-blind, randomized clinical study.

SETTING

University hospital, single institutional.

PARTICIPANTS

Three hundred twenty patients undergoing elective coronary artery surgery were divided into 2 different anesthetic protocols: propofol group (n = 160) and sevoflurane group (n = 160).

INTERVENTIONS

Hemodynamic data were registered before the start of surgery, before the start of CPB, 15 minutes after the end of CPB, at arrival in the intensive care unit, and 6 and 12 hours after arrival in the intensive care unit. Serum glutamic oxaloacetic transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), serum lactate dehydrogenase (LDH), and serum creatinine concentrations were measured before surgery, at arrival in the intensive care unit, and after 6, 12, 24, and 48 hours.

MEASUREMENTS AND MAIN RESULTS

Postoperative levels of serum SGOT, SGPT, and LDH increased transiently in both anesthetic groups, but the increase was significantly lower in the sevoflurane group compared with the propofol group. Creatinine levels remained largely unchanged in both groups.

CONCLUSION

Postoperative biochemical markers of hepatic dysfunction were lower with a sevoflurane-based anesthetic regimen in patients undergoing coronary artery surgery with cardiopulmonary bypass.

Bradykinin B2 receptor antagonist FR173657 ameliorates small bowel ischemia-reperfusion injury in dogs

Bradykinin mediates acute inflammation by increasing microvascular permeability, vasodilation, leukocyte migration and accumulation, and the production of arachidonic acid via phospholipase A2 activation. Arachidonic acid metabolites, or eicosanoids, are potent modulators of biological functions, particularly inflammation. Bradykinin exerts its inflammatory effects via the bradykinin B2 receptor. The aim of this study was to evaluate the effect of a bradykinin B2 receptor antagonist, FR173657 (FR), on intestinal ischemia-reperfusion (I/R) injury. Twenty-eight mongrel dogs were divided into four groups (n = 7 per group). Group I underwent I/R alone, Group II underwent I/R and received FR treatment, Group III was sham operated, and Group IV was sham operated and received FR treatment. The FR treatment consisted of FR continuously from 30 min prior to ischemia to 2 hr after reperfusion. In the I/R procedure, the superior mesenteric artery (SMA) and vein were clamped for 2 hr and then released to permit reperfusion for 12 hr. The intramucosal pH (pHi), SMA blood flow, and mucosal tissue blood flow were measured during the reperfusion period. The serum thromboxane B2 and 6-keto-prostaglandin F1alpha levels were determined, and tissue samples were examined histologically. Results showed that tissue blood flow, pHi, and SMA blood flow after reperfusion were maintained in Group II in comparison with Group I. Histopathological examination showed less severe mucosal damage after reperfusion in Group II than in Group I. The serum thromboxane B2 and 6-keto-prostagland in F1alpha levels were significantly lower in Group II than in Group I (P < 0.05). We conclude that FR treatment appears to have clear protective effects on small bowel I/R injury by inhibiting the release of eicosanoids.

Effects of the phosphodiesterase III inhibitors olprinone, milrinone, and amrinone on hepatosplanchnic oxygen metabolism

OBJECTIVE

To measure the hepatic venous oxygen saturation in patients after cardiac surgery and to compare the effects of olprinone (OLP), a newly synthesized phosphodiesterase III inhibitor, with those of milrinone (MIL) and amrinone (AMR) on hepatosplanchnic oxygen dynamics. Phosphodiesterase III inhibitors are used to improve the hemodynamic state after cardiac surgery. However, the effect of these agents on the hepatosplanchnic circulation has not been investigated thoroughly.

DESIGN

Prospective, randomized study.

SETTING

University hospital intensive care unit (ICU).

PATIENTS

Twenty-nine patients undergoing elective cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

In each patient, a 7.5-Fr oximeter catheter was placed in the hepatic vein via the right femoral vein. Catheterization was completed before admission to the ICU, and the study was performed 8 to 24 hrs after surgery, after obtaining stable systemic hemodynamics in the ICU. The patients were assigned randomly to three groups, and they received one of three drugs for 2 hrs (OLP group, 0.3 microg/kg/min of OLP; MIL group, 0.5 microg/kg/min of MIL; AMR group, 10 microg/kg/min of AMR). The authors did not change the patient's hemodynamic interventions, including catecholamines and vasodilators, throughout the study period. Arterial and hepatic venous blood gas data and hemodynamic data (via a pulmonary artery catheter) were obtained before and after drug infusion. Using these data, the authors calculated systemic oxygen delivery and consumption, the systemic oxygen extraction ratio and the hepatosplanchnic oxygen extraction ratio, and the change in hepatosplanchnic blood flow using Fick's equation. Although the increases in cardiac index were not significantly different among the three groups, hepatic venous oxygen saturation increased significantly only in the OLP group (from 47.1% +/-2.6% to 57.0% +/- 1.5% in the OLP group, from 48.4% +/- 2.3% to 50.9% +/- 2.6% in the MIL group, and from 49.8% +/- 3.6% to 50.8% + +/-.7% in the AMR group). The calculated hepatosplanchnic blood flow change was significantly larger in the OLP group than in the other groups (30.1% +/- 5.7% in the OLP group, 9.3% +/- 5.1% in the MIL group, and 2.6% +/- 6.5% in the AMR group).

CONCLUSIONS

These results suggest that OLP enhances hepatosplanchnic blood flow and thus may be beneficial in protecting the hepatosplanchnic organs after cardiac surgery.

Markers of splanchnic perfusion and intestinal translocation of endotoxins during cardiopulmonary bypass: effects of dopamine and milrinone

OBJECTIVES

To investigate markers of splanchnic perfusion and the extent of endotoxemia during cardiopulmonary bypass (CPB) and to compare the effects of dopamine and milrinone on both splanchnic perfusion and endotoxemia.

DESIGN

Prospective, randomized, blinded study.

SETTING

University teaching hospital.

PARTICIPANTS

Twenty-four patients scheduled for elective coronary artery bypass graft surgery (CABG).

INTERVENTIONS

Patients were allocated to receive placebo (eight patients), dopamine (eight patients), or milrinone (eight patients) during CPB, and at seven times intraoperatively assays were performed of arterial and hepatic venous endotoxin levels, as well as measurements and/or calculations of intramucosal gastric pH (pHi), arterial and hepatic venous lactate-pyruvate ratio (lac/pyr), and hepatic venous oxygen saturation (S(HV)O2).

MEASUREMENTS AND MAIN RESULTS

Both splanchnic and systemic endotoxin levels increased significantly, and this was unaffected by either dopamine or milrinone. Gastric pHi did not change, and there were only modest increases in lac/pyr, which remained within the normal range of less than 10 in both splanchnic and systemic blood. In the placebo group, S(HV)O2 decreased at the onset of CPB and also significantly decreased during rewarming and at the end of CPB and surgery. In the dopamine-treated patients, S(HV)O2 was greater compared with placebo and milrinone during both hypothermic and rewarming phases.

CONCLUSION

Endotoxemia occurs during routine CPB. Neither pHi nor lac/pyr values showed adverse change, but hepatic venous oximetry may be a more sensitive indicator of splanchnic dysoxia in that S(HV)O2 was reduced during rewarming. Whether dopamine or milrinone confer protection against splanchnic ischemia remains uncertain.

Treatment for accidental occlusion of the hepatic artery after hepatic resection: report of two cases

Two patients in whom accidental hepatic artery occlusion (HAO) occurred after hepatic resection (Hx) were reported. A 59-year-old female who underwent Hx for hepatocellular carcinoma with underlying liver cirrhosis developed HAO on postoperative day (POD) 14 and died of hepatic failure on POD 23. The autopsy findings showed multiple necrosis in the remnant liver and an extraluminal hematoma of the hepatic artery, suggesting an injury caused by Pringle's maneuver. The second case was a 53-year-old male who underwent Hx for cholangiocarcinoma without any underlying liver disease. He developed HAO on POD 6, and radiological studies indicated a pseudoaneurysma formation and severe stenosis of the hepatic artery. It was speculated that the cause of the HAO was intraluminal injury of the hepatic artery during an angiographic study conducted prior to Hx. Partial arterialization of the portal vein was performed, following which his liver function test results improved. In both cases, measuring the serum hepatocyte growth factor level and the hepatic vein oxygen saturation proved useful, not only for determining the degree of liver injury, but also for predicting the outcome after treatments for HAO. Furthermore, the partial arterialization of the portal vein for HAO after Hx may rescue the normal remnant liver.