Milrinone modulates endotoxemia, systemic inflammation, and subsequent acute phase response after cardiopulmonary bypass (CPB)

The gut microbiome and cardiac surgery an unusual symphony

The relationship between the gut microbiome and various organ systems has gained interest throughout the scientific community in recent times. The understanding of these complex relationships has greatly improved with clinical benefits now being seen. Cardiopulmonary bypass (CPB) is a form of extracorporeal circulation that provides circulatory and respiratory support during cardiac surgery. This physiological support facilitates a still and bloodless field facilitating operations on the heart to be performed. Through various mechanisms CPB results in a systemic inflammatory response syndrome (SIRS). This response can vary from mild hypotension to multiple organ failure. It remains difficult to predict the degree to which a patient will experience SIRS post-operatively. The relationship between the composition of the gut microbiome and inflammatory processes associated with disease has been seen across several fields including gastroenterology, neurology, psychiatry and cardiology. To date, minimal research has been undertaken to examine the impact the gut microbiome has on outcomes following cardiac surgery. This review paper explores the pathophysiology behind the SIRS response associated with CPB for cardiac surgery and the hypothesis that a correlation exists between a patients gut microbiome composition and the degree of inflammatory response experienced following cardiac surgery.

Assessment of the effect of two regimens of milrinone infusion in paediatric patients with pulmonary artery hypertension undergoing corrective cardiac procedure: A prospective observational study

Background

The aim of the study was to compare the effect of two different regimens of milrinone in pediatric patients with pulmonary artery hypertension (PAH) undergoing corrective procedure.

Materials and Methods

This randomized prospective study included 100 pediatric patients undergoing corrective cardiac surgeries. Group E: Milrinone was started as infusion 0.5 μg/kg/min without a loading dose after induction of anesthesia and continued as infusion 0.5-0.75 μg/kg/min in the pediatric cardiac surgical intensive care unit (PSICU). Group L: Milrinone was started as a loading dose 50 μg/kg over 10 min before weaning from cardiopulmonary bypass (CPB) followed by infusion 0.5-0.75 μg/kg/min in the PSICU. We compared heart rate, mean arterial blood pressure, central venous pressure, cardiac index (CI), mean pulmonary arterial pressure (MPAP), serum lactate level, urine output, vasoactive inotropic score, mechanical ventilation duration, and intensive care unit (ICU)- and hospital length of stay between the groups.

Results

There was an increase in mean arterial blood pressure, CI, and urine output in Group E compared to Group L (P < 0.05). MPAP, serum lactate level, and requirement of inotropes and vasopressors were lower in Group E compared to Group L (P < 0.05). Mechanical ventilation duration, ICU, and hospital length of stay were shorter in Group E than Group L (P < 0.05).

Conclusions

Early use of milrinone in patients with PAH undergoing corrective cardiac surgeries improved CI and mean arterial pressure, decreased MPAP, improved urine output, decreased serum lactate level, and decreased requirement of inotropes and vasopressors after weaning from CPB compared to the milrinone bolus group.

Early administration of milrinone ameliorates lung and kidney injury during sepsis in juvenile rats

BACKGROUND

A sepsis model was created, induced by cecal ligation and puncture (CLP), in juvenile rat groups. Milrinone (MIL), which is known to have a modulatory effect on pro-inflammatory cytokines, was administered to the designated rat groups in the early period before severe sepsis developed. The study was aimed at investigating the possible protective effects of milrinone on the lung and kidney tissues of rats in the late phase of sepsis.

METHODS

The rat pups were divided into seven groups with six animals in each group: (1) healthy rats who received no drug; (2) CLP-S12 (sacrificed at hour 12); (3) CLP-S24 (sacrificed at hour 24); (4) CLP-MIL1-S12 (administered with 0.5 mg/kg milrinone at hour 1 and sacrificed at hour 12); (5) CLP-MIL1-S24 (administered with 0.5 mg/kg milrinone at hour 1 and sacrificed at hour 24): (6) CLP-MIL12-S24 (administered with 0.5 mg/kg milrinone at hour 12 and sacrificed at hour 24), (7) and CLP-MIL1,12-S24 (administered with 0.5 mg/kg milrinone at hours 1 and 12 and sacrificed at hour 24).

RESULTS

Significant differences were found between the early and late administration of milrinone in terms of both molecular and histopathological results. The results showed that the tissues were significantly preserved in the groups in which milrinone had been started in the early period compared to the sepsis control groups and the groups in which milrinone had been started in the late period.

CONCLUSIONS

In addition to the positive inotropic effects of milrinone, its immunomodulatory properties that result in decreased cytokine storm can be beneficial during early period of sepsis.

A Randomized Porcine Study in Low Cardiac Output of Vasoactive and Inotropic Drug Effects on the Gastrointestinal Tract

BACKGROUND

Splanchnic vasodilation by inodilators is an argument for their use in critical cardiac dysfunction. To isolate peripheral vasoactivity from inotropy, such drugs were investigated, and contrasted to vasopressors, in a fixed low cardiac output (CO) model resembling acute cardiac dysfunction effects on the gastrointestinal tract. We hypothesized that inodilators would vasodilate and preserve the aerobic metabolism in the splanchnic circulation in low CO.

METHODS

In anesthetized pigs, CO was lowered to 60% of baseline by partial inferior caval vein balloon inflation. The animals were randomized to placebo (n = 8), levosimendan (24 μg kg-1 bolus, 0.2 μg kg-1 min-1, n = 7), milrinone (50 μg kg-1 bolus, 0.5 μg kg-1 min-1, n = 7), vasopressin (0.001, 0.002 and 0.006 U kg-1 min-1, 1 h each, n = 7) or norepinephrine (0.04, 0.12, and 0.36 μg kg-1 min-1, 1 h each, n = 7). Hemodynamic variables including mesenteric blood flow were collected. Systemic, mixed-venous, mesenteric-venous, and intraperitoneal metabolites were analyzed.

RESULTS

Cardiac output was stable at 60% in all groups, which resulted in systemic hypotension, low superior mesenteric artery blood flow, lactic acidosis, and increased intraperitoneal concentrations of lactate. Levosimendan and milrinone did not change any circulatory variables, but levosimendan increased blood lactate concentrations. Vasopressin and norepinephrine increased systemic and mesenteric vascular resistances at the highest dose. Vasopressin increased mesenteric resistance more than systemic, and the intraperitoneal lactate concentration and lactate/pyruvate ratio.

CONCLUSION

Splanchnic vasodilation by levosimendan and milrinone may be negligible in low CO, thus rejecting the hypothesis. High-dose vasopressors may have side effects in the splanchnic circulation.

Treatment of Subarachnoid Hemorrhage-associated Delayed Cerebral Ischemia With Milrinone: A Review and Proposal

Delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage continues to be associated with high levels of morbidity and mortality. This complication had long been thought to occur secondary to severe cerebral vasospasm, but expert opinion now favors a multifactorial etiology, opening the possibility of new therapies. To date, no definitive treatment option for DCI has been recommended as standard of care, highlighting a need for further research into potential therapies. Milrinone has been identified as a promising therapeutic agent for DCI, possessing a mechanism of action for the reversal of cerebral vasospasm as well as potentially anti-inflammatory effects to treat the underlying etiology of DCI. Intra-arterial and intravenous administration of milrinone has been evaluated for the treatment of DCI in single-center case series and cohorts and appears safe and associated with improved clinical outcomes. Recent results have also brought attention to the potential outcome benefits of early, more aggressive dosing and titration of milrinone. Limitations exist within the available data, however, and questions remain about the generalizability of results across a broader spectrum of patients suffering from DCI. The development of a standardized protocol for milrinone use in DCI, specifically addressing areas requiring further clarification, is needed. Data generated from a standardized protocol may provide the impetus for a multicenter, randomized control trial. We review the current literature on milrinone for the treatment of DCI and propose a preliminary standardized protocol for further evaluation of both safety and efficacy of milrinone.

The effect of milrinone on mortality in adult patients who underwent CABG surgery: a systematic review of randomized clinical trials with a meta-analysis and trial sequential analysis

Background

As an inodilator, milrinone is commonly used for patients who undergo coronary artery bypass graft (CABG) surgery because of its effectiveness in decreasing the cardiac index and mitral regurgitation. The aim of this study was to perform a systematic review and meta-analysis of existing studies from the past 20 years to evaluate the impact of milrinone on mortality in patients who undergo CABG surgery.

Methods

We performed a systematic literature search on the application of milrinone in patients who underwent CABG surgery in studies published between 1997 and 2017 in BioMed Central, PubMed, EMBASE, and the Cochrane Central Register. The included studies evaluated milrinone groups compared to groups receiving either placebo or standard treatment and further compared the systemic administration.

Results

The network meta-analysis included 723 patients from 16 randomized clinical trials. Overall, there was no significant difference in mortality between the milrinone group and the placebo/standard care group when patients underwent CABG surgery. In addition, 9 trials (with 440 randomized patients), 4 trials (with 212 randomized patients), and 10 trials (with 470 randomized patients) reported that the occurrence of myocardial infarction (MI), myocardial ischemia, and arrhythmia was lower in the milrinone group than in the placebo/standard care group. Between the milrinone treatment and placebo/standard care groups, the occurrence of myocardial infarction, myocardial ischemia, and arrhythmia was significantly different. However, the occurrence of stroke and renal failure, the duration of inotropic support (h), the need for an intra-aortic balloon pump (IABP), and mechanical ventilation (h) between these two groups showed no differences.

Conclusions

Based on the current results, compared with placebo, milrinone might be unable to decrease mortality in adult CABG surgical patients but can significantly ameliorate the occurrence of MI, myocardial ischemia, and arrhythmia. These results provide evidence for the further clinical application of milrinone and of therapeutic strategies for CABG surgery. However, along with milrinone application in clinical use, sufficient data from randomized clinical trials need to be collected, and the potential benefits and adverse effects should be analyzed and reevaluated.

Milrinone Attenuates Heart and Lung Remote Injury after Abdominal Aortic Cross-Clamping

BACKGROUND

Phosphodiesterase enzymes play a pivotal role in the pathogenesis of ischemia/reperfusion (IR). We examined the role of milrinone (MIL), a phosphodiesterase 3 inhibitor, on remote injury of the heart and lung after abdominal aortic cross-clamping.

DESIGN

Experimental study.

METHODS

Twenty-one Wistar rats were divided into 3 groups: (1) control (C, n = 7), underwent laparotomy and exploration of abdominal aorta only; (2) IR (n = 7), normal saline was applied intraperitoneally (i.p) before IR induced by clamping of the abdominal aorta for 1 hr and then allowing reperfusion for 1 hr; and (3) MIL + IR (n = 7), MIL was given (0.5 mg/kg, i.p) before IR. After sacrification, the lungs and hearts were taken out for analyses and the tissue malondialdehyde (MDA) and glutathione (GSH) were studied. All tissues were examined under light microscopy and transmission electron microscopy (TEM). Expressions of caveolin (Cav)-1 in the lung and Cav-1 and Cav-3 in the heart were examined immunohistochemically.

RESULTS

The MIL + IR group had significantly a lower magnitude of oxidative stress than the IR group both in the lung and heart (lung: P = 0.03 for MDA and 0.001 for GSH and heart: P = 0.002 for MDA and 0.000 for GSH). In light microscopy, the MIL + IR group had statistically a lower total injury score than the IR group for both the lung and heart tissue (P = 0.03 and P = 0.04, respectively). In TEM, regression of mitochondrial degeneration and lamellar bodies in type II pneumocytes in the lungs and obvious improvements in disruption at the intercalated discs and mitochondrial degeneration in the hearts in the MIL + IR group were detected compared with the IR group. The expression of both Cav-1 and Cav-3 in the MIL + IR group was improved compared with the IR group (P = 0.03 for both).

CONCLUSIONS

MIL attenuates remote injury of heart and lung in lower body IR by inhibiting oxidative stress. Moreover, Cav-1 and Cav-3 might have a potential role in MIL-induced cardioprotection.

Assessment of the effect of two regimens of milrinone infusion in pediatric patients undergoing fontan procedure: A randomized study

Objective:

The aim of the study was to compare the effect of two different regimens of milrinone on hemodynamics and oxygen saturation in pediatric patients undergoing Fontan procedure.

Design:

This was a randomized study.

Setting:

Cardiac centers.

Patients:

This study included 116 patients undergoing Fontan procedure.

Material and Methods:

Group E: Milrinone was started as infusion 0.5 μg/kg/min without a loading dose at the beginning of cardiopulmonary bypass (CPB) followed by infusion 0.5–0.75 μg/kg/min in the pediatric cardiac surgical intensive care unit (PSICU). Group L: Milrinone was started as a loading dose 50 μg/kg over 10 min before weaning from CPB followed by infusion 0.5–0.75 μg/kg/min in the PSICU.

Measurements:

Heart rate, mean arterial blood pressure, central venous pressure, transpulmonary pressure, cardiac index, pharmacological support, lactate level, urine output, oxygen saturation, ICU, and hospital length of stay.

Main Results:

There were no changes in the heart rate and mean arterial blood pressure (P > 0.05). The increase in the postoperative central venous pressure, transpulmonary pressure and lactate level was lower in Group E than Group L (P < 0.05). The increase in the postoperative cardiac index, oxygen saturation, and urine output was higher in Group E than Group L (P < 0.05). The requirement for pharmacological support was lower in the Group E (P < 0.05). The ICU and hospital length of stay were shorter in the Group E than Group L (P < 0.05).

Conclusion:

Early use of milrinone during Fontan procedure facilitated the weaning from CPB, decreased the elevation in the central venous pressure, transpulmonary gradient pressure, and the requirement for pharmacological support. Furthermore, it increased the cardiac index and arterial oxygen saturation.

Endotoxin Activity in Neonates Undergoing Cardiac Surgery: Cohort Study

BACKGROUND

Endotoxemia in pediatric cardiac surgical patients is poorly understood. The endotoxin activity assay (EAA) levels were examined in neonates undergoing cardiac surgery in order to assess their reference levels and their association with other pre-, intra-, and postoperative risk factors for gut hypoperfusion. We finally observed if refeeding was associated with modification of endotoxin levels.

METHODS

In a prospective cohort study, neonates undergoing surgery for correction or palliation were enrolled. Preterm birth, weight below 1.5 kg, the need for extracorporeal membrane oxygenation, and urgent surgery were exclusion criteria.

RESULTS

Among the 26 enrolled neonates, 12 underwent on-pump and 14 off-pump surgery, 22 received a preoperative infusion of prostaglandin E2. Overall, 11 patients were surgically corrected and 15 received a palliation. Endotoxin activity assay baseline levels were inversely correlated with age at surgery ( r = -.50, P = .006) and they increased to postoperative day2 ( P = .002). On-pump versus off-pump surgery ( P =.36) and surgical palliation with a Blalock-Taussig shunt versus correction ( P = .45) did not predict increase in EAA levels. Aortic clamping for coarctation repair was associated with the lowest levels ( P = .04). Systolic, mean, and diastolic pressures were associated with EAA levels ( r = -.55, P = .01; r = -.45, P = .02; r = -.37, P = .04, respectively). Endotoxin activity assay levels after refeeding were similar to baseline levels. Patients with abdominal distension and feeding intolerance showed higher median peak EAA levels (0.7, 0.66-1.11) than asymptomatic patients (0.53, 0.35-0.64; P = .01).

CONCLUSIONS

Endotoxin activity assay levels increase after elective neonatal surgery and are not modified by refeeding. High postoperative levels may predict feeding intolerance.

The Inflammatory Response to Cardiopulmonary Bypass— Should It Be Treated?

Proinflammatory cytokines, including tumor necrosis factor (TNF) α and the interieukins, are important in the metabolic response to injury or infection. Although the importance of cytokine release during cardiopulmonary bypass (CPB) is not fully appreciated, increasing num bers of publications present evidence that cytokine release during CPB is detrimental. In addition, endoge nous inhibitors of cytokine function, including TNF-sol uble receptor and interleukin 1 receptor antagonist, are released in response to elevated proinflammatory cyto kine levels during and after CPB. The involvement of these endogenous inhibitors in the pathophysiology of proinflammatory cytokine-induced solid organ injury after CPB remains to be defined.

Routine clinical markers of the magnitude of the systemic inflammatory response after elective operation: a systematic review

BACKGROUND

Operative injury to the body from all procedures causes a stereotypical cascade of neuroendocrine, cytokine, myeloid, and acute phase responses. This response has been examined commonly by the use of cortisol, interleukin-6 (IL-6), white cell count, and C-reactive protein (CRP). We aimed to determine which markers of the systemic inflammatory response were useful in determining the magnitude of injury after elective operations.

METHODS

A systematic review of the literature was performed using surgery, endocrine response, systemic inflammatory response, cortisol, IL-6, white cell count, and CRP. For each analyte the studies were grouped according to whether the operative injury was considered to be minor, moderate, or major and then by the operative procedure.

RESULTS

A total of 164 studies were included involving 14,362 patients. The IL-6 and CRP responses clearly were associated with the magnitude of operative injury and the invasiveness of the operative procedure. For example, the peak CRP response increased from 52 mg/L with cholecystectomy to 123 mg/L with colorectal cancer resection, 145 mg/L with hip replacement, 163 mg/L after abdominal aortic aneurysm repair, and 189 mg/L after open cardiac surgery. There also appeared to be a difference between minimally invasive/laparoscopic and open procedures such as cholecystectomy (27 vs 80 mg/L), colorectal cancer resection (97 vs 133 mg/L), and aortic aneurysm repair (132 vs 180 mg/L).

CONCLUSION

Peak IL-6 and CRP concentrations consistently were associated with the magnitude of operative injury and operative procedure. These markers may be useful in the objective assessment of which components of Enhanced Recovery after Surgery are likely to improve patient outcome and to assess the possible impact of operative injury on immune function.

Milrinone attenuates arteriolar vasoconstriction and capillary perfusion deficits on endotoxemic hamsters

Background and Objective

Apart from its inotropic property, milrinone has vasodilator, anti-inflammatory and antithrombotic effects that could assist in the reversal of septic microcirculatory changes. This paper investigates the effects of milrinone on endotoxemia-related microcirculatory changes and compares them to those observed with the use of norepinephrine.

Materials and Methods

After skinfold chamber implantation procedures and endotoxemia induction by intravenous Escherichia coli lipopolysaccharide administration (2 mg.kg-1), male golden Syrian hamsters were treated with two regimens of intravenous milrinone (0.25 or 0.5 μg.kg-1.min-1). Intravital microscopy of skinfold chamber preparations allowed quantitative analysis of microvascular variables. Macro-hemodynamic, biochemical, and hematological parameters and survival rate were also analyzed. Endotoxemic non-treated animals, endotoxemic animals treated with norepinephrine (0.2 μg.kg-1.min-1), and non-endotoxemic hamsters served as controls.

Results

Milrinone (0.5 μg.kg-1.min-1) was effective in reducing lipopolysaccharide-induced arteriolar vasoconstriction, capillary perfusion deficits, and inflammatory response, and in increasing survival. Norepinephrine treated animals showed the best mean arterial pressure levels but the worst functional capillary density values among all endotoxemic groups.

Conclusion

Our data suggests that milrinone yielded protective effects on endotoxemic animals’ microcirculation, showed anti-inflammatory properties, and improved survival. Norepinephrine did not recruit the microcirculation nor demonstrated anti-inflammatory effects.

Comparison of hypertonic saline versus normal saline on cytokine profile during CABG

Background and the purpose of the study

Blood contact with artificial surfaces of the extracorporeal circuit and ischemia-reperfusion injury in CABG with CPB, may lead to a systemic inflammatory response. Hypertonic saline have been recently investigated as a fluid in order to decrease inflammatory response and cytokines generation in patients undergo cardiac operations. Our purpose is to study the prophylactic effect of HS 5% infusion versus NS on serum IL-6 as an inflammatory & IL-10 as an anti-inflammatory biomarker in CABG patients.

Methods

The present study is a randomized double-blinded clinical trial. 40 patients undergoing CABG were randomized to receive HS 5% or NS before operation. Blood samples were obtained after receiving HS or NS, just before operation, 24 and 48 hours post-operatively. Plasma levels of IL-6 and IL-10 were measured by ELISA.

Results and major conclusion

Patients received HS had lower levels of IL-6 and higher level of IL-10 compared with NS group, however these differences were not statistically significant. Results of this study suggest that pre-treatment with small volume hypertonic saline 5% may have beneficial effects on inflammatory response following CABG operation.

Protective effects of penehyclidine hydrochloride on liver injury in a rat cardiopulmonary bypass model

BACKGROUND AND OBJECTIVE

Hepatic injury after cardiac surgery is considered to be a consequence of cardiopulmonary bypass (CPB). The aim of this study was to test the hypothesis that penehyclidine hydrochloride (PHC) could attenuate hepatic injury using a rat CPB model.

METHODS

Male Sprague-Dawley rats were randomly divided into six groups (eight per group), including sham-operated control, sham low-dose PHC control (0.6 mg kg), sham high-dose PHC control (2.0 mg kg), vehicle control, low-dose PHC (0.6 mg kg) and high-dose PHC (2.0 mg kg)-treated groups. Blood samples were collected from the femoral artery at the cessation of CPB and the serum levels of the liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were determined. The ultrastructure of liver tissue was also examined under an electron microscope.

RESULTS

In the sham-operated groups, high-dose PHC and low-dose PHC had no significant impact on the levels of respiratory rate, heart rate, blood pressure, ECG, ALT or AST. Compared with the sham group, the serum levels of ALT and AST were increased significantly in the surgical groups. PHC alleviated all the biochemical and histopathological changes in a dose-dependent manner. The ALT and AST levels in the high-dose PHC-treated groups were significantly lower than those in the vehicle control group.

CONCLUSION

Treatment with penehyclidine hydrochloride could improve liver function during CPB.

Hepatic and renal protection during cardiac surgery

Hepatic injury in cardiac surgery is a rare complication but is associated with significant morbidity and mortality. A high index of suspicion postoperatively will lead to earlier treatment directed at eliminating or minimizing ongoing hepatic injury while preventing additional metabolic stress from ischemia, hemorrhage, or sepsis. The evidence-basis for perioperative renal risk factors remains hampered by the inconsistent definitions for renal injury. Although acute kidney injury (as defined by the Risk, Injury, Failure, Loss, End-stage criteria) has become accepted, it does not address pathogenesis and bears little relevance to cardiac surgery. Although acute renal failure requiring renal replacement therapy after cardiac surgery is rare, it has a devastating impact on morbidity and mortality, and further studies on protective strategies are essential.

Advances in gastrointestinal complications in cardiac surgery

Gastrointestinal (GI) complications are serious in cardiac surgery, and definite diagnosis is often delayed to due to the absence of early specific clinical signs. They are associated with higher mortality rates and medical costs. The preoperative and intraoperative predictors associated with an increased incidence of postoperative GI complications after cardiopulmonary bypass are of great importance, and investigations of these factors may lead to earlier identification of patients at an increased risk and allow more efficient and earlier interventions to reduce the mortality rate.

Metabolic effects of phosphodiesterase III inhibitors: another reason to promote their use?

Phosphodiesterase III inhibitors combine positive inotropic and vasodilator properties. These inhibitors are therefore frequently used to treat low cardiac output and/or severe left heart failure associated with cardiac surgery. Their effects on energy metabolism and visceral organ function are not well studied, however, particularly in comparison with their 'competitors' in daily practice (that is, catecholamines).

Propofol attenuates intestinal mucosa injury induced by intestinal ischemia-reperfusion in the rat

PURPOSE

We investigated whether propofol at a sedative dose can prevent intestinal mucosa ischemia/reperfusion (I/R) injury, and if propofol can attenuate oxidative stress and increases in nitric oxide (NO) and endothelin-1 (ET-1) release that may occur during intestinal I/R injury.

METHODS

Rats were randomly allocated into one of five groups (n=10 each): (i) sham control; (ii) injury (one hour superior mesenteric artery occlusion followed by three hours reperfusion); (iii) propofol pre-treatment, with propofol given 30 min before inducing intestinal ischemia; (iv) simultaneous propofol treatment, with propofol given 30 min before intestinal reperfusion was started; (v) propofol post-treatment, with propofol given 30 min after intestinal reperfusion was initiated. In the treatment groups, propofol 50 mg x kg(-1) was administrated intraperitoneally. Animals in the control and untreated injury groups received equal volumes of intralipid (the vehicle solution of propofol) intraperitoneally. Intestinal mucosa histology was analyzed by Chiu's scoring assessment. Levels of lactic acid (LD), NO, ET-1, lipid peroxidation product malondialdehyde (MDA) and superoxide dismutase (SOD) activity in intestinal mucosa were determined.

RESULTS

Histological results showed severe damage in the intestinal mucosa of the injury group accompanied by increases in MDA, NO and ET-1 and a decrease in SOD activity. Propofol treatments, especially pre-treatment, significantly reduced Chiu's scores and levels of MDA, NO, ET-1 and LD, while restoring SOD activity.

CONCLUSION

These findings indicate that propofol attenuates intestinal I/R-induced mucosal injury in an animal model. The response may be attributable to propofol's antioxidant properties, and the effects of inhibiting over-production of NO and in decreasing ET-1 levels.

Inhaled milrinone: a new alternative in cardiac surgery?

The administration of milrinone through inhalation has been studied in only a few animal and human studies. Compared to the intravenous administration, inhaled milrinone has been shown to reduce pulmonary artery pressure without systemic hypotension. Therefore, this approach could represent an alternative to nitric oxide. This current state of knowledge of intravenous and inhaled milrinone is presented and summarized.

Selecting a Vasopressor Drug for Vasoplegic Shock After Adult Cardiac Surgery: A Systematic Literature Review

The choice of vasopressors to treat vasodilatory shock after cardiac surgery is a matter of controversy. We have systematically reviewed the literature and found that the data are insufficient to guide choice of agent. However, we found sufficient evidence that when a target blood pressure can not be achieved with a single agent, addition of another is more likely to help achieve the blood pressure target. We also found that there is no evidence that vasopressors induce organ ischemia. Finally, the lack of high quality data indicate that large multicenter trials are needed in this field.

Modulation of systemic inflammatory response after cardiac surgery

Cardiac surgery and cardiopulmonary bypass initiate a systemic inflammatory response largely determined by blood contact with foreign surfaces and the activation of complement. It is generally accepted that cardiopulmonary bypass initiates a whole-body inflammatory reaction. The magnitude of this inflammatory reaction varies, but the persistence of any degree of inflammation may be considered potentially harmful to the cardiac patient. The development of strategies to control the inflammatory response following cardiac surgery is currently the focus of considerable research efforts. Diverse techniques including maintenance of hemodynamic stability, minimization of exposure to cardiopulmonary bypass circuitry, and pharmacologic and immunomodulatory agents have been examined in clinical studies. This article briefly reviews the current concepts of the systemic inflammatory response following cardiac surgery, and the various therapeutic strategies being used to modulate this response.

Levosimendan in cardiac surgery

OBJECTIVE

Levosimendan is a new calcium sensitizer with inodilatory properties. There is growing clinical experience with levosimendan given to cardiac surgical patients. The aim of this report was to evaluate the effects of perioperative use of levosimendan in surgical patients with high perioperative risk, compromised left ventricular (LV) function, or difficulties in weaning from cardiopulmonary bypass (CPB).

DESIGN

Case series.

SETTING

Single-institution, university hospital.

PARTICIPANTS

Patients undergoing cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Sixteen cardiac surgical patients received levosimendan infusion with a maximum duration of 29 hours. Eight were initiated preoperatively and 8 postoperatively. Coronary artery disease was the main operative indication in 10 of 16 cases, and 75% of the patients were high-risk patients.

RESULTS

Continuous levosimendan infusion increased cardiac index significantly in both groups compared with preoperative baseline. Pulmonary capillary wedge pressure and systolic blood pressure did not change significantly. Norepinephrine and epinephrine were the most common concomitant vasoactive medications. Most importantly, weaning from CPB was successful in all patients even after failure to wean the patient with catecholamines. One high-risk patient in the preoperative group and 2 patients in the postoperative group died in the hospital. Another patient died during the 1-year follow-up.

CONCLUSION

Levosimendan can be used for postoperative rescue therapy for patients difficult to wean from CPB. Also, elective preoperative initiation of levosimendan seems applicable to patients with high perioperative risk or compromised LV function.

Ginsenosides compound (shen-fu) attenuates gastrointestinal injury and inhibits inflammatory response after cardiopulmonary bypass in patients with congenital heart disease

OBJECTIVE

This study was undertaken to demonstrate that gastrointestinal mucosal injury occurs during cardiopulmonary bypass in children, increasing systemic inflammatory responses, and to determine whether shen-fu injection (the major components of which are ginsenosides compound, extract of Panax ginseng shown to have antioxidant properties) could attenuate gastrointestinal mucosal injury and subsequent inflammatory responses.

METHODS

Twenty-four children undergoing heart surgery for congenital heart defects were randomly assigned to groups C (placebo control, n = 12) and G (1.35 mg/kg ginsenosides compound intravenously before and throughout the course of cardiopulmonary bypass, n = 12). Central venous blood samples were taken before cardiopulmonary bypass and at 60 and 120 minutes after aortic declamping (reperfusion). Gastric intramucosal pH was measured by perioperative tonometry. Plasma lipid peroxidation product malondialdehyde, myocardium-specific creatine kinase isoenzyme MB activity, diamine oxidase, lipopolysaccharide, and interleukin 6 were all measured.

RESULTS

Significant decrease in gastric intramucosal pH and increase in plasma diamine oxidase were seen during reperfusion in group C, accompanied by increases in plasma levels of malondialdehyde, lipopolysaccharide, interleukin 6, and creatine kinase isoenzyme MB (P < .01 vs before cardiopulmonary bypass). Shen-fu injection significantly attenuated these changes (P < .05). Consequently, fewer patients in group G (2/12) than in group C (7/12) needed postoperative inotropic support. Postoperative intensive care unit stay was shorter in group G than in group C. A tight positive correlation was seen between diamine oxidase and interleukin 6 at 60 minutes after aortic declamping and between diamine oxidase and lipopolysaccharide at 120 minutes after aortic declamping (r = 0.79, P < .0001).

CONCLUSION

Ginsenosides compound may attenuate gastrointestinal injury and inhibit inflammatory response after cardiopulmonary bypass in patients with congenital heart disease.

Abdominal organ injury after cardiac surgery

Gastrointestinal complications occur in about 2.5% of patients undergoing cardiac surgery, are associated with a high mortality (about 33%), and account for nearly 15% (and perhaps increasing) of all postoperative deaths. The various complications and risk factors are reviewed. Splanchnic ischemia prior to, during, and especially postoperatively appears to be an important cause of these complications. In addition, splanchnic ischemia is hypothesized to be one cause of the systemic inflammatory response syndrome and multiorgan failure that may follow cardiac surgery. The physiology of splanchic perfusion and the effects of cardiac surgery, including cardiopulmonary bypass, on it are reviewed. Finally, possible methods to minimize splanchnic ischemia and reduce the incidence of abdominal complications are discussed.

Levosimendan is superior to milrinone and dobutamine in selectively increasing microvascular gastric mucosal oxygenation in dogs*

OBJECTIVE

The effect of levosimendan, a novel inotropic vasodilator (inodilator), on the microvascular gastric mucosal hemoglobin oxygenation (muHbo(2)) is unknown. A possible effect could thereby be selective for the splanchnic region or could primarily reflect changes in systemic oxygen transport (Do(2)) and/or oxygen consumption (Vo(2). We compared systemic and regional effects of levosimendan with those of established inotropes, milrinone and dobutamine.

DESIGN

Laboratory experiment.

SETTING

University animal research laboratory of experimental anesthesiology.

SUBJECTS

Chronically instrumented dogs with flow probes for cardiac output measurement.

INTERVENTIONS

Anesthetized, mechanically ventilated dogs (each group n = 6) on different days randomly received levosimendan (10 microg.kg, followed by four infusion steps: 0.125-1.0 microg.kg.min), milrinone (5.0 microg.kg, followed by 1.25-10 microg.kg.min), or dobutamine (2.5-10.0 microg.kg.min). Since these drugs may modify regional or systemic responses to fluid load, an additional predefined volume challenge was subsequently performed with hydroxyethyl starch 6% (10 mL.kg).

MEASUREMENTS AND MAIN RESULTS

We measured muHbo(2) (reflectance spectrophotometry), Do(2), Vo(2), and systemic hemodynamics. Levosimendan significantly increased muHbo(2) from baseline (approximately 55% for all groups) to 64 +/- 4% and further to 69 +/- 2% with volume challenge (mean +/- sem). At the systemic level, levosimendan alone only slightly increased Do(2) at a Vo(2). Milrinone elicited similar systemic effects (Do(2), Vo(2), hemodynamics) but failed to increase muHbo(2). Dobutamine, conversely, increased muHbo(2) to a similar extent as levosimendan; however, this was accompanied by marked increases in Do(2) and Vo(2). The gastric mucosa selectivity of these interventions, expressed as slope of the muHbo(2)/Do2 relation, was highest for levosimendan (+1.89 and +1.14, without and with volume challenge), compared with milrinone (+0.45 and + 0.47) and dobutamine (+0.48 and + 0.33).

CONCLUSIONS

Levosimendan is superior to milrinone (no significant regional effects) and dobutamine (marked systemic effects) in increasing gastric mucosal oxygenation selectively (i.e., at only moderately increased Do(2) and stable Vo(2). If our experimental data apply to the clinical setting, levosimendan may serve as an option to selectively increase gastrointestinal mucosa oxygenation in patients at risk to develop splanchnic ischemia.

Bench-to-bedside review: Inotropic drug therapy after adult cardiac surgery -- a systematic literature review

Many adult patients require temporary inotropic support after cardiac surgery. We reviewed the literature systematically to establish, present and classify the evidence regarding choice of inotropic drugs. The available evidence, while limited in quality and scope, supports the following observations; although all β-agonists can increase cardiac output, the best studied β-agonist and the one with the most favourable side-effect profile appears to be dobutamine. Dobutamine and phosphodiesterase inhibitors (PDIs) are efficacious inotropic drugs for management of the low cardiac output syndrome. Dobutamine is associated with a greater incidence of tachycardia and tachyarrhythmias, whereas PDIs often require the administration of vasoconstrictors. Other catecholamines have no clear advantages over dobutamine. PDIs increase the likelihood of successful weaning from cardiopulmonary bypass as compared with placebo. There is insufficient evidence that inotropic drugs should be selected for their effects on regional perfusion. PDIs also increase flow through arterial grafts, reduce mean pulmonary artery pressure and improve right heart performance in pulmonary hypertension. Insufficient data exist to allow selection of a specific inotropic agent in preference over another in adult cardiac surgery patients. Multicentre randomized controlled trials focusing on clinical rather than physiological outcomes are needed.

The prophylactic use of the beta-blocker esmolol in combination with phosphodiesterase III inhibitor enoximone in elderly cardiac surgery patients

We assessed the influence of the prophylactic use of a combination of the IV beta-adrenergic blocker, esmolol, and the phosphodiesterase III inhibitor, enoximone, on postbypass hemodynamic status, inflammation, and endothelial and organ function in a prospective, randomized, placebo-controlled study in 42 patients aged >65 yr undergoing aortocoronary bypass grafting. In 21 patients, esmolol (aim: heart rate <70 bpm) plus enoximone (initial bolus of 0.5 mg/kg followed by a continuous infusion of 2.5 microg x kg(-1) x min(-1)) was started after induction of anesthesia and continued until the morning of the first postoperative day; another 21 patients received saline solution as placebo. Hemodynamics, splanchnic perfusion (gastric-arterial CO(2) gap), liver function (glutathione transferase-alpha plasma levels), renal function (creatinine clearance, urine concentrations of N-acetyl-beta-D-glucosaminidase), myocardial ischemia (creatine-kinase MB and troponin T plasma levels), inflammation (elastase, interleukin-6 and -8 plasma levels), and endothelial integrity (adhesion molecules plasma levels) were assessed at baseline, before and after cardiopulmonary bypass (CPB), and in the intensive care unit until the first postoperative day. Catecholamine requirements were significantly less in the treated than in the nontreated patients. Heart rate was significantly slower, cardiac index was higher, and gastric-arterial CO(2) gap was significantly lower in the treatment group. Troponin T, beta-N-acetyl-beta-D-glucosaminidase, glutathione transferase-alpha, and soluble adhesion molecules increased significantly in the untreated control, but remained almost normal in the esmolol+enoximone patients. Inflammatory responses (elastase/interleukins) were attenuated by esmolol+enoximone. We conclude that, in comparison to an untreated control, the prophylactic use of a combination of esmolol and enoximone in elderly patients undergoing cardiac surgery with cardiopulmonary bypass resulted in overall beneficial effects on postbypass hemodynamic status, organ function, inflammatory response, and endothelial integrity.

PMEA Coating of Pump Circuit and Oxygenator May Attenuate the Early Systemic Inflammatory Response in Cardiopulmonary Bypass Surgery

We investigated the effects of coating a cardiopulmonary bypass (CPB) circuit and oxygenator with poly-2-methoxy-ethyl acrylate (PMEA) on the systemic inflammatory response during and after CPB. Thirty patients undergoing elective cardiac surgery were randomized into three groups (each group n = 10): noncoated (group N), heparin coated (group H), and PMEA coated circuit and oxygenator (group X). Bradykinin (BK), complement 3 activation (C3a) and interleukin-6 (IL-6) levels were measured as early phase indicators of inflammatory response, as were maximum C reactive proteins (CRP) and white blood cell (WBC) levels. The alveolar-arterial oxygen gradient (A-a DO2) was measured as a parameter of respiratory function. IL-6 levels after CPB were significantly higher in group N than in groups H and X (p < 0.05). Serum BK and C3a levels showed similar patterns in all groups. A-a DO2 was lower at the end of and 3 hours after CPB in groups H and X than in group N (p < 0.05). Maximum CRP levels were lower in group X than in groups N (p < 0.05). This prospective study suggests that PMEA coated CPB may improve respiratory function and decrease systemic inflammatory response after cardiac surgery, possibly because this circuit is as biocompatible as heparin coated CPB circuit.

A review of anti-inflammatory strategies in cardiac surgery

It is generally accepted that cardiac surgery is frequently associated with the development of systemic inflammatory response. This phenomenon is very variable clinically, and can be detected by measuring plasma concentrations of certain inflammatory markers. Complement component, cytokines and adhesion molecules are examples of these markers. Systemic inflammation can be potentially damaging to major organs. Several anti-inflammatory strategies have been used in recent years, aiming to attenuate the development of systemic inflammatory response. This article summarizes recently published literature concerning the use of anti-inflammatory techniques and pharmacological agents in cardiac surgery. In particular, the anti-inflammatory effects of off-pump surgery, leukocyte filtration, corticosteroids, aprotinin, phosphodiesterase inhibitors, dpoexamine, H2 antagonists and ACE inhibitors are reviewed. The overall conclusion is that although certain strategies reduce plasma levels of inflammatory mediators, convincing evidence of significant clinical benefits is yet to come.

Serum amyloid A is a better early predictor of severity than C-reactive protein in acute pancreatitis

BACKGROUND

Serum amyloid A (SAA) is an early and sensitive marker of the extent of tissue trauma and inflammation. The aim of this study was to compare the early prognostic accuracy of SAA with that of serum C-reactive protein (CRP) in acute pancreatitis.

METHODS

In a prospective multicentre trial, plasma SAA and CRP levels were measured in patients with severe and mild acute pancreatitis, and in a control group with acute abdominal pain. Plasma samples were collected on admission and at 6-h intervals for 48 h, every 12 h between 48 and 72 h, then daily for 5 days. Plasma SAA was measured by a new enzyme-linked immunosorbent assay and CRP was measured by immunoturbidometry.

RESULTS

There were 137 patients with mild and 35 with severe acute pancreatitis, and 74 control patients. SAA levels were significantly higher in patients with severe acute pancreatitis than in those with mild acute pancreatitis, on admission, at 24 h or less after symptom onset, and subsequently. Whereas plasma CRP concentration was also significantly higher in patients with severe acute pancreatitis on admission, it failed to distinguish mild from severe acute pancreatitis until 30-36 h after symptom onset. SAA levels predicted severity (sensitivity 67 per cent, specificity 70 per cent, negative predictive value 89 per cent, mean(s.d.) area under curve 0.7(0.05)) significantly better than CRP (57 per cent, 60 per cent, 84 per cent, 0.59(0.06) respectively) on admission (P = 0.02) and at 24 h following symptom onset (area under curve 0.65(0.09) versus 0.58(0.09) respectively; P < or = 0.02).

CONCLUSION

Plasma SAA concentration is an early marker of severity in acute pancreatitis and is superior to CRP estimation on hospital admission and at 24 h or less after symptom onset. This study suggests that plasma SAA concentration is clinically useful, with the potential to replace CRP in the management of acute pancreatitis.

Serum amyloid A is a better early predictor of severity than C-reactive protein in acute pancreatitis

BACKGROUND

Serum amyloid A (SAA) is an early and sensitive marker of the extent of tissue trauma and inflammation. The aim of this study was to compare the early prognostic accuracy of SAA with that of serum C-reactive protein (CRP) in acute pancreatitis.

METHODS

In a prospective multicentre trial, plasma SAA and CRP levels were measured in patients with severe and mild acute pancreatitis, and in a control group with acute abdominal pain. Plasma samples were collected on admission and at 6-h intervals for 48 h, every 12 h between 48 and 72 h, then daily for 5 days. Plasma SAA was measured by a new enzyme-linked immunosorbent assay and CRP was measured by immunoturbidometry.

RESULTS

There were 137 patients with mild and 35 with severe acute pancreatitis, and 74 control patients. SAA levels were significantly higher in patients with severe acute pancreatitis than in those with mild acute pancreatitis, on admission, at 24 h or less after symptom onset, and subsequently. Whereas plasma CRP concentration was also significantly higher in patients with severe acute pancreatitis on admission, it failed to distinguish mild from severe acute pancreatitis until 30-36 h after symptom onset. SAA levels predicted severity (sensitivity 67 per cent, specificity 70 per cent, negative predictive value 89 per cent, mean(s.d.) area under curve 0.7(0.05)) significantly better than CRP (57 per cent, 60 per cent, 84 per cent, 0.59(0.06) respectively) on admission (P = 0.02) and at 24 h following symptom onset (area under curve 0.65(0.09) versus 0.58(0.09) respectively; P < or = 0.02).

CONCLUSION

Plasma SAA concentration is an early marker of severity in acute pancreatitis and is superior to CRP estimation on hospital admission and at 24 h or less after symptom onset. This study suggests that plasma SAA concentration is clinically useful, with the potential to replace CRP in the management of acute pancreatitis.

Intravenous milrinone in cardiac surgery

Phosphodiesterase inhibitors including milrinone produce positive inotropic effects by slowing the hydrolysis of cyclic adenosine monophosphate in the myocardium. With a loading dose of 50 microg/kg followed by an infusion of 0.5 microg x kg(-1) x min(-1), milrinone increases stroke volume index and left ventricular velocity of circumferential fiber shortening after weaning from cardiopulmonary bypass. Milrinone has potential for the treatment and prevention of internal mammary artery spasm because of its vasodilative effect, which is similar to that of papaverine, and is a potent pulmonary vasodilator for patients with right ventricular dysfunction and pulmonary vasoconstriction. Low-dose milrinone may have antiinflammatory properties and potentially can improve splanchnic perfusion.

The efficacy of preemptive Milrinone or Amrinone therapy in patients undergoing coronary artery bypass grafting

Acute deterioration in ventricular function and oxygen transport is common after cardiac surgery. We hypothesized that milrinone or amrinone may reduce their occurrence and catecholamine requirements and increase cellular enzyme levels in patients undergoing coronary artery bypass. In 45 patients, we randomly administered milrinone 50 microg/kg plus 0.5 microg x kg(-1) x min(-1) infusion for 10 h, amrinone 1.5 mg/kg plus 10 microg x kg(-1) x min(-1) infusion for 10 h, or placebo at release of aortic cross-clamp. Hemodynamic variables, dopamine requirement, and laboratory values were recorded. At the postoperative nadir, stroke volume index was higher in the Milrinone and Amrinone groups (mean +/- SD, 27.8 +/- 4.0 and 26.1 +/- 3.2 vs. 20.4 +/- 5.1 mL x min (-1) x m(-2) per beat, P < 0.0001), and oxygen transport index was higher (354.7 +/- 57.8 and 353.7 +/- 91.2 vs 283.0 +/- 83.9 mL. min(-1) x m(-2), P = 0.009). The postoperative dopamine requirement was less (6.6 +/- 2.7 and 6.8 +/- 2.6 vs 10.4 +/- 2.0 mg/kg, P < 0.008), and postoperative serum lactate, alanine and aspartate aminotransferase, lactate dehydrogenase, creatinine kinase, C-reactive protein, and glucose levels were less (P < 0.01). The mean postoperative heart rate was faster in the Milrinone group than in the Amrinone and Placebo groups (96.8 +/- 10.3 vs. 86.9 +/- 9.5 and 87.8 +/- 10.8 bpm, P < 0.01). Milrinone and amrinone administered preemptively reduce postoperative deterioration in cardiac function and oxygen transport, dopamine requirement, and increases in serum lactate, glucose, and enzyme levels, although milrinone may increase heart rate.

IMPLICATIONS

Preemptive milrinone or amrinone administration before separation from cardiopulmonary bypass in cardiac surgical patients not only ameliorates postoperative deterioration in cardiac function and oxygen transport, but also reduces dopamine requirement and increases serum lactate, glucose, and cellular enzyme levels, although milrinone may increase heart rate.

Influence of aminosteroid and glucocorticoid treatment on inflammation and immune function during cardiopulmonary bypass

OBJECTIVE

During cardiopulmonary bypass, inflammation and immunosuppression is present. We measured circulating mediators and monocyte-based functions and tested the hypothesis that these variables are influenced by methylprednisolone (MP) or tirilazad mesylate (TM) treatment.

DESIGN

Randomized, controlled, double-blind prospective trial.

SETTING

A university hospital.

PATIENTS

Thirty-nine patients scheduled for conventional coronary surgery with three-vessel disease.

INTERVENTIONS

Preoperative application of MP (15 mg/kg) or TM (10 mg/kg) compared with placebo (PL).

MEASUREMENTS AND MAIN RESULTS

Circulating proinflammatory markers including interleukin (IL)-6, IL-8, monocyte chemoattractant protein 1, and C-reactive protein were all decreased by MP treatment but not by TM treatment. Whereas rapid increases in circulating anti-inflammatory IL-10 were superinduced by MP but not TM, plasma levels of IL-1RA and transforming growth factor beta were not altered by either treatment. Decreased ex vivo lipopolysaccharide-stimulated secretion of tumor necrosis factor alpha was prolonged after MP treatment but not after TM treatment. Perioperative stimulated secretion of IL-12 and interferon gamma was diminished in all groups, whereas ex vivo IL-1RA secretion tended to increase in all groups. Depression of monocyte surface expression of HLA-DR was significantly greater in patients treated with MP, whereas CD14 expression did not change.

CONCLUSIONS

These data confirm that, during cardiopulmonary bypass, pro- and anti-inflammatory systems are activated at the same time, whereas monocyte-based immune functions are depressed. Treatment with MP abrogates proinflammatory mediators and induces a shift toward anti-inflammation at the cost of further functional monocyte deficits, whereas treatment with TM apparently has neither anti-inflammatory nor immunosuppressive actions in this setting.

Enoximone in contrast to dobutamine improves hepatosplanchnic function in fluid-optimized septic shock patients

OBJECTIVE

To investigate the impact of dobutamine and enoximone on hepatosplanchnic perfusion and function in fluid-optimized septic patients.

DESIGN

Prospective, randomized, double-blinded interventional study.

SETTING

Intensive care unit of a university hospital.

PATIENTS

Forty-eight septic shock patients were examined within 12 hrs after onset of septic shock. Patients were conventionally resuscitated, achieving an optimal pulmonary artery occlusion pressure at which the left ventricular stroke work was on the maximal plateau. Liver blood flow was estimated by venous suprahepatic catheterization using the continuous indocyanine green infusion technique. Microsomal liver function was assessed by the plasma appearance of monoethylglycinexylidide, and release of hepatic tumor necrosis factor-alpha (TNF-alpha) was measured to estimate the severity of hepatic ischemia-reperfusion syndrome.

INTERVENTIONS

Patients were randomly treated with dobutamine or enoximone. Within the first 10 hrs after baseline measurements, the dosage was increased until no further increase in the left ventricular stroke work index occurred. Then, positive inotropes were kept constant throughout the study.

MEASUREMENTS AND MAIN RESULTS

Measurements were performed at baseline and after 12 and 48 hrs after baseline measurements. Cardiac index, systemic oxygen delivery, systemic oxygen consumption, and liver blood flow increased significantly in both groups during treatment (p <.01) without a significant difference between groups. Fractional liver blood flow (liver blood flow/cardiac index) did not change in the enoximone group and showed a significant but only minor (median, 10%) decrease in the dobutamine group (p <.05 after 12 hrs and p <.01 after 48 hrs vs. baseline). After 12 hrs of enoximone treatment, monoethylglycinexylidide kinetics and hepatosplanchnic oxygen consumption demonstrated a significant increase (p <.05). The release of hepatic TNF-alpha after 12 hrs of dobutamine treatment was twice as high (p <.05) as during enoximone.

CONCLUSION

The increase in hepatosplanchnic oxygen consumption, together with an increased lignocaine metabolism and decreased release of hepatic TNF-alpha, indicates improved hepatosplanchnic function and antiinflammatory properties after 12 hrs of enoximone treatment. Therefore, if the inflammatory response should be attenuated in high-risk patients, administration of enoximone in fluid-optimized septic shock patients may be favorable compared with dobutamine.

Effects of olprinone, a new phosphodiesterase inhibitor, on gastric intramucosal acidosis and systemic inflammatory responses following hypothermic cardiopulmonary bypass

BACKGROUND

Phosphodiesterase (PDE) III inhibitors have both an inotropic and a peripheral vasodilatory effect, and also inhibit the activation of macrophages. Thus a newly developed PDE III inhibitor, olprinone, could modify gastric intramucosal pH (pHi), systemic oxygen consumption, and systemic inflammatory responses in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

We studied 23 patients. In 15 patients, olprinone (0.1 or 0.2 microg x kg(-1) x min(-1)) was administered from the commencement of CPB until their admission to the ICU. The other 8 patients received placebo. The pHi and regional CO2 tension (PrCO2) were assessed by a capnometric air tonometry. Systemic inflammatory responses were evaluated by serum interleukin-6 (IL-6), IL-10, and leucocyte counts.

RESULTS

The pHi and PCO2-gap, the difference between PrCO2 and arterial CO2 tension (PaCO2), showed a transient decrease and an increase after CPB, respectively. Although olprinone did not affect pHi, olprinone at 0.2 microg x kg(-1) x min(-1) significantly lessened post-CPB increase in PCO2-gap. Olprinone at 0.2 microg x kg(-1) x min(-1) significantly increased IL-10 and reduced the extent of leucocytosis, while it did not affect IL-6 levels. At the same dosage, olprinone also lessened the surge in systemic oxygen uptake index (VO2) and augmented the increase in mixed oxygen saturation (SvO2) both of which occurred after CPB. At 0.1 microg x kg(-1) x min(-1), however, olprinone did not show any significant effect.

CONCLUSION

Our results suggest that olprinone at 0.2 microg x kg(-1) x min(-1) suppresses gastric intramucosal acidosis and systemic inflammation following CPB.

Effect of low-dose milrinone on gastric intramucosal pH and systemic inflammation after hypothermic cardiopulmonary bypass

OBJECTIVE

To investigate the usefulness of low-dose milrinone on gastric intramucosal pH (pHi) and systemic inflammation in patients undergoing hypothermic cardiopulmonary bypass (CPB).

DESIGN

Prospective randomized study.

SETTING

University hospital.

PARTICIPANTS

Twenty patients scheduled for cardiac surgery.

INTERVENTIONS

Ten patients were administered a low dose of milrinone, 0.25 microg/kg/min, from the initiation of CPB to 1 hour after admission to the intensive care unit. The other patients were administered saline. Supplemental inotropes and intravenous fluid were given to obtain adequate mean arterial blood pressure and pulmonary artery occlusion pressure.

MEASUREMENTS AND RESULTS

Gastric pHi and carbon dioxide pressure (PCO2) were assessed by capnometric air tonometry. The difference between PCO2 and arterial carbon dioxide pressure (PaCO2), PCO2-gap, was also examined. Systemic inflammatory responses were evaluated by serum interleukin-6 and leukocyte counts. Hemodynamics, oxygen delivery index, and oxygen uptake index were monitored with catheters in the radial and pulmonary arteries (thermodilution). The hepatic venous blood flow and left ventricular flow were measured using transesophageal echocardiography. Milrinone prevented gastric intramucosal acidosis, detected as a decrease in pHi or an increase in PCO2-gap, without affecting hepatic venous blood flow. Increases in interleukin-6, leukocyte count, and oxygen uptake index, all of which developed after CPB, were significantly less in the milrinone group than in the control group.

CONCLUSION

These results suggest that in patients undergoing hypothermic CPB, supplemental low-dose milrinone prevents gastric intramucosal acidosis and increases in some markers of systemic inflammation.