The role of the gut in the development of multiple organ dysfunction in cardiothoracic patients

Strategies to attenuate maladaptive inflammatory response associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) initiates an intense inflammatory response due to various factors: conversion from pulsatile to laminar flow, cold cardioplegia, surgical trauma, endotoxemia, ischemia-reperfusion injury, oxidative stress, hypothermia, and contact activation of cells by the extracorporeal circuit. Redundant and overlapping inflammatory cascades amplify the initial response to produce a systemic inflammatory response, heightened by coincident activation of coagulation and fibrinolytic pathways. When unchecked, this inflammatory response can become maladaptive and lead to serious postoperative complications. Concerted research efforts have been made to identify technical refinements and pharmacologic interventions that appropriately attenuate the inflammatory response and ultimately translate to improved clinical outcomes. Surface modification of the extracorporeal circuit to increase biocompatibility, miniaturized circuits with sheer resistance, filtration techniques, and minimally invasive approaches have improved clinical outcomes in specific populations. Pharmacologic adjuncts, including aprotinin, steroids, monoclonal antibodies, and free radical scavengers, show real promise. A multimodal approach incorporating technical, circuit-specific, and pharmacologic strategies will likely yield maximal clinical benefit.

Evaluation of the NMR-MOUSE as a new method for continuous functional monitoring of the small intestine during different perfusion states in a porcine model

Objective

The study aim was to evaluate a small low-field NMR (nuclear magnetic resonance) scanner, the NMR-MOUSE^®, for detecting changes in intestinal diffusion under different (patho-) physiological perfusion states.

Methods

Laparotomy was performed on 8 female landrace pigs (body weight 70±6 kg) and the feeding vessels of several intestinal loops were dissected. Successively, the intestinal loops were examined using O2C (oxygen to see, LEA Medizintechnik GmbH, Giessen, Germany) for microcirculatory monitoring and the NMR-MOUSE^® for diffusion measurement (fast and slow components). On each loop the baseline measurement (physiological perfusion) was followed by one of the following main procedures: method 1 –ischemia; method 2 –flow reduction; method 3 –intraluminal glucose followed by ischemia; method 4 –intraluminal glucose followed by flow reduction. Additionally, standard perioperative monitoring (blood pressure, ECG, blood gas analyses) and histological assessment of intestinal biopsies was performed.

Results

There was no statistical overall time and method effect in the NMR-MOUSE measurement (fast component: p_time = 0.6368, p_method = 0.9766, slow component: p_time = 0.8216, p_method = 0.7863). Yet, the fast component of the NMR-MOUSE measurement showed contrary trends during ischemia (increase) versus flow reduction (decrease). The slow-to-fast diffusion ratio shifted slightly towards slow diffusion during flow reduction. The O2C measurement showed a significant decrease of oxygen saturation and microcirculatory blood flow during ischemia and flow reduction (p < .0001). The local microcirculatory blood amount (rHb) showed a significant mucosal increase (p_{Clamping(method 1)} = 0.0007, p_{Clamping(method 3)} = 0.0119), but a serosal decrease (p_{Clamping(method 1)} = 0.0119, p_{Clamping(method 3)} = 0.0078) during ischemia. The histopathological damage was significantly higher with increasing experimental duration and at the end of methods 3 and 4 (p < .0001,Fisher-test).

Conclusion

Monitoring intestinal diffusion changes due to different perfusion states using the NMR-MOUSE is feasible under experimental conditions. Despite the lack of statistical significance, this technique reflects perfusion changes and therefore seems promising for the evaluation of different intestinal perfusion states in the future. Beforehand however, an optimization of this technology, including the optimization of the penetration depth, as well as further validation studies under physiological conditions and including older animals are required.

Ischemic Colitis after Cardiac Surgery: Can We Foresee the Threat?

Introduction

Ischemic colitis (IC) remains a great threat after cardiac surgery with use of extracorporeal circulation. We aimed to identify predictive risk factors and influence of early catecholamine therapy for this disease.

Methods

We prospectively collected and analyzed data of 224 patients, who underwent laparotomy due to IC after initial cardiac surgery with use of extracorporeal circulation during 2002 and 2014. For further comparability 58 patients were identified, who underwent bypass surgery, aortic valve replacement or combination of both. Age ±5 years, sex, BMI ± 5, left ventricular function, peripheral arterial disease, diabetes and urgency status were used for match-pair analysis (1:1) to compare outcome and detect predictive risk factors. Highest catecholamine doses during 1 POD were compared for possible predictive potential.

Results

Patients’ baseline characteristics showed no significant differences. In-hospital mortality of the IC group with a mean age of 71 years (14% female) was significantly higher than the control group with a mean age of 70 (14% female) (67% vs. 16%, p<0.001). Despite significantly longer bypass time in the IC group (133 ± 68 vs. 101 ± 42, p = 0.003), cross-clamp time remained comparable (64 ± 33 vs. 56 ± 25 p = 0.150). The majority of the IC group suffered low-output syndrome (71% vs. 14%, p<0.001) leading to significant higher lactate values within first 24h after operation (55 ± 46 mg/dl vs. 31 ± 30 mg/dl, p = 0.002). Logistic regression revealed elevated lactate values to be significant predictor for colectomy during the postoperative course (HR 1.008, CI 95% 1.003–1.014, p = 0.003). However, Receiver Operating Characteristic Curve calculates a cut-off value for lactate of 22.5 mg/dl (sensitivity 73% and specificity 57%). Furthermore, multivariate analysis showed low-output syndrome (HR 4.301, CI 95% 2.108–8.776, p<0.001) and vasopressin therapy (HR 1.108, CI 95% 1.012–1.213, p = 0.027) significantly influencing necessity of laparotomy.

Conclusion

Patients who undergo laparotomy for IC after initial cardiac surgery have a substantial in-hospital mortality risk. Early postoperative catecholamine levels do not influence the development of an IC except vasopressin. Elevated lactate remains merely a vague predictive risk factor.

Acute respiratory distress syndrome after cardiac surgery

Acute respiratory distress syndrome (ARDS) is a leading cause of postoperative respiratory failure, with a mortality rate approaching 40% in the general population and 80% in the subset of patients undergoing cardiac surgery. The increased risk of ARDS in these patients has traditionally been associated with the use of cardiopulmonary bypass (CPB), the need for blood product transfusions, large volume shifts, mechanical ventilation and direct surgical insult. Indeed, the impact of ARDS in the cardiac population is substantial, affecting not only survival but also in-hospital length of stay and long-term physical and psychological morbidity. No patient undergoing cardiac surgery can be considered ARDS risk-free. Early identification of those at higher risk is crucial to warrant the adoption of both surgical and non-surgical specific preventative strategies. The present review focuses on epidemiology, risk assessment, pathophysiology, prevention and management of ARDS in the specific setting of patients undergoing cardiac surgery.

Pulmonary Complications After Cardiac Surgery

Over the past two decades there has been a steady evolution in the practice of adult cardiac surgery with the introduction of “off-pump” surgery. However, respiratory complications remain a leading cause of postcardiac surgical morbidity and can prolong hospital stays and increase costs. The high incidence of pulmonary complications is in part due to the disruption of normal ventilatory function that is inherent to surgery in the thoracic region. Furthermore, patients undergoing such surgery often have underlying illnesses such as intrinsic lung disease (e.g., chronic obstructive pulmonary disease) and pulmonary dysfunction secondary to cardiac disease (e.g., congestive heart failure) that increase their susceptibility to postoperative respiratory problems. Given that many patients undergoing cardiac surgery are thus susceptiple to pulmonary complications, it is remarkable that more patients do not suffer from them during and after cardiac surgery. This is to a large degree because of advances in anesthetic, surgical and critical care that, for example, have reduced the physiological insults of surgery (e.g., better myocardial preservation techniques) and streamlined care in the immediate postoperative period (e.g., early extubation). Moreover, the development of minimally invasive surgery and nonbypass techniques are further evidence of the attempts at reducing the homeostatic disruptions of cardiac surgery. This review examines the available information on the incidences, consequences, and treatments of postcardiac surgery respiratory complications.

Acute Gastrointestinal Complications after Open Heart Surgery

Retrospective analysis revealed that 24 of 4401 adult patients (0.5%) developed severe gastrointestinal complications after open heart surgery during a 3-year period from January 1995. There were 4 women (17%) and 20 men (83%). Mean age was 61.7 ± 2.02 years. Gastrointestinal bleeding (33.3%), mesenteric ischemia (20.8%), pancreatitis (20.8%), hepatic dysfunction (16.7%), and cholecystitis (16.7%) were the most common complications. Mortality was 41.7% (10 patients). During the same period, mortality in the patients who did not develop gastrointestinal complications was 1.89% (p < 0.0001). Emergency basis, reoperation, combined operations, peripheral vascular disease, diabetes mellitus, chronic lung disease, and impaired left ventricle function were found to be risk factors for the development of postoperative gastrointestinal complications.

Extracorporeal circulation increases proliferation in the intestinal mucosa in a large animal model

OBJECTIVE

Extracorporeal circulation induces ischemia/reperfusion injury in the small intestinal wall. One reason for this damage is a perfusion shift from the muscular toward the mucosal layer. This study investigated the effect of this perfusion shift on the small-intestinal apoptosis and proliferation.

METHODS

Twenty-eight pigs were randomly assigned to the following cohorts and underwent a thoracolaparotomy and a 1 hour main procedure: cohort I: control; cohort II: thoracic aortic cross-clamping (TAC) without perfusion; cohort III: TAC and distal aortic perfusion (DAP); cohort IV: TAC, DAP, and selective visceral perfusion. The main procedure was followed by 2 hours of reperfusion in all cohorts. Tissue samples were taken during the experiment, stained, and analyzed for apoptosis and proliferation (caspase-3, annexin-V, terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling, and proliferating cell nuclear antigen). Six animals died unexpectedly during the experiment and were excluded from the analysis.

RESULTS

Extensive tissue damage and necrosis was only found in cohort II after the main procedure. In the mucosa, the proliferation was increased in cohort III at the end of the experiment (P = .0157 cohort I vs II). In contrast, the annexin-V/proliferating cell nuclear antigen ratio was significantly higher in cohorts II and IV than in cohorts I and II at the end of the experiment (P = .0034). Furthermore, the caspase-3/annexin-V ratio was increased in all cohorts at the end of the experiment (P = .0015).

CONCLUSIONS

Mucosal proliferation is the early repair mechanism of the limited small intestinal ischemia/reperfusion injury after DAP. Furthermore, the extensive surgical trauma shifted the mucosal apoptosis into an advanced state.

Population pharmacokinetics of phenytoin in critically ill children

The objective was to study the population pharmacokinetics of bound and unbound phenytoin in critically ill children, including influences on the protein binding profile. A population pharmacokinetic approach was used to analyze paired protein-unbound and total phenytoin plasma concentrations (n = 146 each) from 32 critically ill children (0.08-17 years of age) who were admitted to a pediatric hospital, primarily intensive care unit. The pharmacokinetics of unbound and bound phenytoin and the influence of possible influential covariates were modeled and evaluated using visual predictive checks and bootstrapping. The pharmacokinetics of protein-unbound phenytoin was described satisfactorily by a 1-compartment model with first-order absorption in conjunction with a linear partition coefficient parameter to describe the binding of phenytoin to albumin. The partitioning coefficient describing protein binding and distribution to bound phenytoin was estimated to be 8.22. Nonlinear elimination of unbound phenytoin was not supported in this patient group. Weight, allometrically scaled for clearance and volume of distribution for the unbound and bound compartments, and albumin concentration significantly influenced the partition coefficient for protein binding of phenytoin. The population model can be applied to estimate the fraction of unbound phenytoin in critically ill children given an individual's albumin concentration.

Acute bowel ischemia after heart operations

Acute bowel ischemia is a perioperative complication that is frequently unrecognized as a cause of death after cardiac surgical procedures, with an in-hospital mortality of 50% to 100%. In recent years, controversy regarding the most appropriate approach to resolve clinical or laboratory suspicion and the limited therapeutic options have led to very little improvement in patient prognosis. This article reviews the related literature examining the actual prevalence, pathophysiologic mechanisms, predisposing factors, diagnostic tests, and therapeutic approaches providing a glance at new promising tools in diagnostic workup.

Microcirculatory perfusion shift in the gut wall layers induced by extracorporeal circulation

OBJECTIVE

Extracorporeal circulation (ECC) is regularly applied to maintain organ perfusion during major aortic and cardiovascular surgery. During thoracoabdominal aortic repair, ECC-driven selective visceral arterial perfusion (SVP) results in changed microcirculatory perfusion (shift from the muscularis toward the mucosal small intestinal layer) in conjunction with macrohemodynamic hypoperfusion. The underlying mechanism, however, is unclear. Therefore, the aim of this study was to assess in a porcine model whether ECC itself or the hypoperfusion induced by SVP is responsible for the mucosal/muscular shift in the small intestinal wall.

METHODS

A thoracoabdominal aortic approach was performed in 15 healthy pigs divided equally into three groups: group I, control; group II, thoracic aortic cross-clamping with distal aortic perfusion; and group III, thoracic aortic cross-clamping with distal aortic perfusion and SVP. Macrocirculatory and microcirculatory blood flow was assessed by transit time ultrasound volume flow measurement and fluorescent microspheres. In addition, markers for metabolism and intestinal ischemia-reperfusion injury were determined.

RESULTS

ECC with a roller pump induced a significant switch from the muscularis and mucosal layer of the small intestine, even with adequate macrocirculation (mucosal/muscular perfusion ratio: group I vs II, P = .005; group I vs III, P = .0018). Furthermore, the oxygen extraction ratio increased significantly in groups II (>30%) and III (>40%) in the beginning of the ECC compared with the control (group I vs II, P = .0037; group I vs III, P = .0062). Lactate concentrations and pH values did not differ between groups I and II; but group III demonstrated a significant shifting toward a lactate-associated acidosis (lactate: group I vs III, P = .0031; pH: group I vs III, P = .0001).

CONCLUSIONS

We demonstrated a significant shifting between the small intestinal gut wall layers induced by roller pump-driven ECC. The shift occurs independently of macrohemodynamics, with a significant effect on aerobic metabolism in the gut wall. Consequently, an optimal intestinal perfusion cannot be guaranteed by a roller pump; therefore, perfusion techniques need to be optimized.

Splanchnic vasoregulation after major abdominal surgery in pigs

BACKGROUND

Unrecognized reduction of blood supply to intestinal organs is associated with significant postoperative morbidity in abdominal surgery. The aim of this study was to determine whether--in the absence of hypovolemia--intestinal hypoperfusion as a result of blood flow redistribution occurs after abdominal surgery.

METHODS

Standardized operative trauma was induced in 14 healthy pigs. Systemic, regional, and local blood flow, intestinal and gastric intraluminal-to-end-tidal pCO(2) gradients representing mucosal perfusion, and oxygen transport variables were measured for 10 postoperative hours. Normovolemia was maintained using continuous infusion of Ringer's lactate and additional boluses of colloids in response to blood pressure, pulmonary wedge pressure, and urinary output.

RESULTS

Postoperative blood flow was significantly increased in the celiac trunk (76% increase [percentage of baseline flow], p = 0.003) and the hepatic (136% increase, p = 0.002) and splenic (36% increase, p = 0.025) arteries. Blood flow was significantly decreased in the mesenteric artery (25% decrease, p = 0.007) and portal vein (13% decrease, p = 0.028). Carotid and renal artery blood flow remained unchanged.

CONCLUSIONS

Maintenance of normovolemia is insufficient to protect from intestinal hypoperfusion after abdominal surgery. Postoperative redistribution of cardiac output results in decreased intestinal and increased hepatic and splenic arterial blood flow.

Impact of bloodstream infections on outcome and the influence of prophylactic oral antibiotic regimens in allogeneic hematopoietic SCT recipients

This study aimed to determine the impact of blood stream infections (BSIs) on outcome of allogeneic hematopoietic SCT (HSCT), and to examine the influence of old (non-levofloxacin-containing) and new (levofloxacin-based) prophylactic antibiotic protocols on the pattern of BSIs. We retrospectively enrolled 246 allogeneic HSCT recipients between January 1999 and June 2006, dividing patients into BSI (within 6 months post-HSCT, n=61) and non-BSI groups (n=185). We found that Gram-negative bacteria (GNB) predominated BSI pathogens (54%). Multivariate analyses showed that patients with a BSI, compared with those without, had a significantly greater 6-month mortality (hazard ratio, 1.75; 95% confidence interval, 1.09-2.82; P=0.021) and a significantly increased length of hospital (LOH) stay (70.8 vs 55.2 days, P=0.014). Moreover, recipients of old and new protocols did not have a significantly different 6-month mortality and time-to-occurrence of BSIs. However, there were significantly more resistant GNB to third-generation cephalosporins and carbapenem in recipients of levofloxacin-based prophylaxis. Our data suggest that BSIs occur substantially and impact negatively on the outcome and LOH stay after allogeneic HSCT despite antibiotic prophylaxis. Levofloxacin-based prophylaxis, albeit providing similar efficacy to non-levofloxacin-containing regimens, may be associated with increased antimicrobial resistance.

Impact of selective decontamination of the digestive tract on multiple organ dysfunction syndrome: systematic review of randomized controlled trials

OBJECTIVE

We examined the impact of selective decontamination of the digestive tract on multiple organ dysfunction syndrome.

DATA SOURCES

We searched MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, previous meta-analyses, and meetings proceedings.

STUDY SELECTION

We included all randomized trials comparing both oropharyngeal and intestinal administration of antibiotics in selective decontamination of the digestive tract with or without a parenteral component, with placebo or standard therapy used in the controls.

DATA EXTRACTION

Two reviewers independently applied selection criteria, performed quality assessment, and extracted the data. The primary end point was the number of patients with multiple organ dysfunction syndrome developing during intensive care unit stay. Secondary end points were overall mortality and multiple organ dysfunction syndrome-related mortality. Odds ratios were pooled with the random effect model.

DATA SYNTHESIS

We identified seven randomized trials including 1270 patients. Multiple organ dysfunction syndrome was found in 132 of 637 patients (20.7%) in the selective decontamination of the digestive tract group and in 219 of 633 patients (34.6%) in the control group (odds ratio, 0.50; 95% confidence interval, 0.34-0.74; p < .001). Overall mortality for selective decontamination of the digestive tract vs. control patients was 119 of 637 (18.7%) and 145 of 633 (22.9%), respectively, demonstrating a nonsignificant reduction in the odds of death (odds ratio, 0.82; 95% confidence interval, 0.51-1.32; p = .41). In five studies including 472 patients, multiple organ dysfunction syndrome-related mortality was demonstrated in 31 of 239 (13%) patients in selective decontamination of the digestive tract group and 37 of 233 (15.9%) in the controls (odds ratio, 0.84; 95% confidence interval, 0.48-1.41; p = .54).

CONCLUSIONS

Selective decontamination of the digestive tract reduces the number of patients with multiple organ dysfunction syndrome. Mortality was not significantly reduced, probably because of the small sample size.

The role of endogenous and exogenous ligands for the peroxisome proliferator-activated receptor alpha (PPAR-alpha) in the regulation of inflammation in macrophages

The aim of the present study was to evaluate the role of endogenous and exogenous peroxisome proliferator-activated receptor alpha (PPAR-alpha), a nuclear receptor, on the regulation of inflammation in macrophages. To address this question, we have stimulated peritoneal macrophages from PPAR-alpha wild-type mice and PPAR-alpha knockout mice (PPAR-alpha) with 10 microg/mL LPS and 100 U/mL IFN-gamma. We report here that the absence of a functional PPAR-alpha gene in PPAR-alpha knockout mice resulted in a significant augmentation of various inflammatory parameters in peritoneal macrophages. In particular, we have clearly demonstrated that PPAR-alpha gene deletion increases (1) the mitogen-activated protein kinase phosphorylation (extracellular signal-regulated kinase, c-Jun NH2-terminal kinase, and p38), (2) nuclear factor-kappaB activation, (3) IkappaB-alpha degradation, (4) iNOS expression and NO formation, and (5) cyclooxygenase 2 expression and prostaglandin E2 formation caused by LPS/IFN-gamma stimulation. On the contrary, the incubation of peritoneal macrophages from PPAR-alpha wild type with clofibrate (2 mM) at 2 h before the LPS and IFN-gamma stimulation significantly reduced the expression and the release of the proinflammatory mediators. To elucidate whether the protective effects of clofibrate is related to activation of the PPAR-alpha receptor, we also investigated the effect of clofibrate treatment on PPAR-alpha-deficient mice. The absence of the PPAR-alpha receptor significantly abolished the protective effect of the PPAR-alpha agonist against LPS/IFN-gamma-induced macrophage inflammation. In conclusion, our study demonstrates that the endogenous and exogenous PPAR-alpha ligands reduce the degree of macrophage inflammation caused by LPS/IFN-gamma stimulation.

Prospective comparison of eubacterial PCR and measurement of procalcitonin levels with blood culture for diagnosing septicemia in intensive care unit patients

Rapid identification of infection has a major impact on the clinical course, management, and outcome of critically ill intensive care unit (ICU) patients. We compared the results of PCR and procalcitonin with blood culture for ICU patients suspected of having septicemia. Ninety patients (60 patients meeting the criteria for sepsis and 30 patients not meeting the criteria for sepsis) were evaluated. Compared with blood culture as the gold standard, the sensitivity, specificity, and positive and negative predictive values for PCR were 100%, 43.33%, 46.87%, and 100%, respectively, and for procalcitonin were 100%, 61.66%, 56.6%, and 100%, respectively. The average times required to produce a final result were as follows: PCR, 10 h; blood culture, 33 h; procalcitonin, 45 min. Both PCR and procalcitonin may be useful as rapid tests for detecting septicemia but compared with blood cultures lacked specificity.

Carbohydrate supplementation before operation retains intestinal barrier function and lowers bacterial translocation in a rat model of major abdominal surgery

BACKGROUND

Overnight fasting of rats augments the susceptibility of the small intestine to ischemia-reperfusion damage. Feeding before surgery may improve injuries to distant organs that were induced by ischemia-reperfusion. The present study tested the hypothesis that one of the food constituents, namely carbohydrates, may be responsible for the protective effect of preoperative feeding on postoperative organ dysfunction.

METHODS

Male Wistar rats were fed ad libitum for 5 d and had either free access to water or free access to a carbohydrate drink and water. Then they were fasted for 16 h and access remained to either water or a carbohydrate drink and water. Following this, the arteria mesenterica superior was clamped for 60 min followed by 180 min of reperfusion. Subsequently, the intestinal permeability of stripped ileum was determined by measuring the mucosal to serosal flux in Ussing chambers. For assessment of bacterial content, organs were aseptically removed and assessed for bacterial content by culture under anaerobic conditions.

RESULTS

Preoperative supplementation with carbohydrates resulted in a better maintenance of intestinal barrier function when compared with water supplemented animals. Moreover, carbohydrate supplementation resulted in a reduction in the ischemiareperfusion-induced increase in bacterial content of the liver, kidney, and mesenteric lymph nodes.

CONCLUSIONS

Preoperative intake of carbohydrates by rats retains both the intestinal barrier function and prevents translocation of bacteria to distant organs.

Pathological changes in the gastrointestinal tract of a heavily radiation-exposed worker at the Tokai-mura criticality accident

Gastrointestinal syndrome after high-dose acute radiation whole body exposure is difficult to treat, although it is a well-known complication. In this report, we describe the clinical and pathological features of a patient who died after the criticality accident which occurred in Japan on 30 September 1999. The patient was estimated to have been exposed to 16-25 Gy equivalent of gamma ray, and died of multiple organ failure after acute radiation syndrome, especially gastrointestinal syndrome, on day 82. The stomach and small intestine contained a large amount of blood clots and the gastrointestinal epithelial cells were almost totally depleted at autopsy. In addition, the degree of the mucosal damage was dependent on the segment of the gastrointestinal tract; the mucosa of stomach, ileum and ascending colon was entirely depleted, but the esophagus, descending and sigmoid colon and rectum retained a small portion of the epithelial cells. From the posture of the patient at the time of exposure, the absorbed dose was presumed to be highest in the right-anterior abdomen. This agreed with the pathological differences in the mucosal damage by the position in the abdomen, which depended presumably on the radiation dose. This is the first report documenting the relationship between the absorbed dose and the severity of gastrointestinal damages in vivo.

Gastrointestinal complications after coronary artery bypass grafting: a national study of morbidity and mortality predictors

BACKGROUND

Previous single-institution studies have documented a 0.6% to 2.4% incidence of gastrointestinal (GI) complications after coronary artery bypass grafting (CABG), with an associated 14% to 63% mortality rate. To better determine the incidence and impact of GI complications after CABG, national outcomes for CABG were examined from 1998 to 2002.

STUDY DESIGN

The Nationwide Inpatient Sample was queried for all patients undergoing CABG (ICD9 procedure codes 36.10 to 36.16). Two cohorts were compared: CABGs with and without GI complications. Both demographic and outcomes variables were compared by either t-test or chi-square analysis. Logistic regression analyses indicated potential predictors of CABG inpatient mortality and GI complications after CABG.

RESULTS

The incidence of GI complications among 2.7 million CABGs identified was 4.1%. Total hospital length of stay (19.3 versus 8.8 days) and inpatient mortality (12.0% versus 2.5%, both p < 0.0001) were increased in CABG patients having GI complications. Factors associated with increased risk of GI complications included: age greater than 65 years (odds ratio [OR], 2.1); hemodialysis (OR, 3.4); intraaortic balloon pump (OR, 1.6); concomitant valve procedure (OR, 1.5); and procedure urgency (OR, 1.22). Use of an internal mammary graft was protective (OR, 0.5), but GI complications increased inpatient mortality risk (OR, 2.6).

CONCLUSIONS

This national population-based study indicates that GI complications after CABG occur at a higher rate than previously described, leading to increased hospital length of stay and mortality.

Manipulation of nitric oxide in an animal model of acute liver injury. The impact on liver and intestinal function

BACKGROUND

Nitric oxide may have a protective effect on the liver during endotoxemia and chronic inflammation. There is evidence that it maintains liver and intestinal tissue integrity during inflammatory processes. We evaluated the impact of altering nitric oxide release on acute liver injury, the associated gut injury and bacterial translocation, at different time intervals.

METHODS

An acute rat liver injury model induced by D-galactosamine was used. Sprague Dawley rats were divided into four main groups: normal control, acute liver injury control, acute liver injury + N-nitro-L-arginine methyl ester (L-NAME), acute liver injury + L-NAME + L-arginine. Each group was divided into three subgroups according to the different time intervals (6, 12, 24 hours) after the induction of the liver injury. Liver enzymes and bilirubin were evaluated, as well as bacterial translocation, cecal and colonic microflora, and histological study of liver, ileum and cecum.

RESULTS

Liver enzymes increased significantly at all time intervals in acute liver injury + L-NAME compared to liver injury control groups. Bacterial translocation increased significantly in liver injury + L-NAME groups; at 6 hours to the liver, at 12 hours to the liver and mesenteric lymph nodes (MLNs), and at 24 hours to arterial and portal blood, liver and MLNS. Inhibition of nitric oxide increased significantly the Enterobacteriaceae count in cecum compared to normal and liver injury control groups. The G-negative anaerobes increased significantly in the colon compared to the liver injury control group.

CONCLUSION

Inhibition of nitric oxide in an acute liver injury model potentiates the liver injury as evidenced by increased appearance of hepatocellular necrosis and elevated liver enzymes and bilirubin. It increases the Enterobacteriaceae in both cecum and colon and Gnegative anaerobes in the colon. It also increases bacterial translocation to extra-intestinal sites. The increased bacterial translocation could be one of the mechanisms potentiating liver injury and nitric oxide may be pathophysiologically involved. Further studies are required to confirm this hypothesis.

Abdominal Complications After Heart Surgery

BACKGROUND

Up to 3% of patients undergoing heart surgery suffer from an intraabdominal complication (IAC). These complications carry a high mortality besides adding to the morbidity and cost. This review was undertaken to see if a subset of patients with increased risk of IAC could be identified.

METHODS

Medical records of 7,731 consecutive patients undergoing heart surgery in a single center were screened for identification of postoperative IAC. One hundred and twenty (120) cases were found. One hundred and six (106) cases were compared with the same number of matched controls.

RESULTS

Significant predictors of the development of IAC were increased cardiopulmonary bypass times (> 99 minutes), peripheral vascular disease, chronic steroid use, and low left ventricular ejection fraction. Patients on postoperative antiplatelet therapy or warfarin had a lower risk of IAC. Significant predictors of mortality in IAC were increased cardiopulmonary bypass times (> or = 120 minutes.), use of inotropes, cerebral vascular disease, and incremental age.

CONCLUSIONS

A subset of patients can be identified who are at higher risk for IAC and an associated adverse outcome. Patients who have prolonged cardiopulmonary bypass, have a low left ventricular ejection fraction, are on steroids, and suffer from other vascular disease should be observed carefully for development of IAC. Postoperative anticlotting strategies may be helpful. Early diagnosis and intervention are essential for improving outcomes in cases of IAC.

Preventing prolonged post-operative ileus in gastric cancer patients undergoing gastrectomy and intra-peritoneal chemotherapy

AIM: To assess the efficacy of metoclopramide (Met) for prevention of prolonged post-operative ileus in advanced gastric cancer patients undergoing D2 gastrectomy and intra-peritoneal chemotherapy (IPC).

METHODS: Thirty-two advanced gastric cancer patients undergoing D2 gastrectomy and IPC were allocated to two groups. Sixteen patients received Met immediately after operation (group A), and 16 did not (group B). Another 16 patients who underwent D2 gastrectomy without IPC were enrolled as the control group (group C). All patients had received epidural pain control. The primary endpoints were time to first post-operative flatus and time until oral feeding with a soft diet without discomfort. Secondary endpoints were early complications during hospitalization.

RESULTS: Gender, the type of resection, operating time, blood loss, tumor status and amount of narcotics were comparable in the three groups. However, the group C patients were older than those in groups A and B (67.5±17.7 vs 56.8±13.2, 57.5±11.7 years, P = 0.048). First bowel flatus occurred after 4.35±0.93 d in group A, 4.94±1.37 d in group B, and 4.71±1.22 d in group C (P>0.05). Oral feeding of a soft diet was tolerated 7.21±1.92 d after operation in group A, 10.15±2.17 d in group B, and 7.53±1.35 d in group C (groups A and C vs group B, P<0.05). There was no significant difference in respect to the first flatus among the three groups. However, the time of tolerating oral intake with soft food in groups A and C patients was significantly shorter than that in group B patients. Levels of C-reactive protein (CRP) were significantly lower in group C and there was a more prominent and prolonged response in CRP level in patients undergoing IPC. The incidence of post-operative complications was similar in the three groups except for prolonged post-operative ileus. There was no increased risk of anastomotic leakage in patients receiving Met.

CONCLUSION: The results suggest that a combination of intravenous Met and epidural pain control may be required to achieve a considerable decrease in time to resumption of oral soft diet in advanced gastric cancer patients who underwent gastrectomy and IPC. Furthermore, the administration of Met did not increase anastomotic leakage. Met has a role in the prevention of prolonged post-operative ileus.

Preoperative feeding preserves heart function and decreases oxidative injury in rats

OBJECTIVE

The nutritional status of a patient has been implicated as an important factor in the development of postoperative complications. Fasting before an operation may have detrimental effects on the metabolic state. We hypothesized that there was a positive correlation between preoperative nutritional status and postoperative organ function.

METHODS

Preoperative feeding was compared with fasting with respect to effects on organ function and biochemical parameters in an animal model of extensive large abdominal surgery. Male Wistar rats were fed ad libitum or fasted for 16 h, after which the arteria mesenterica superior was clamped for 60 min followed by 180 min of reperfusion.

RESULTS

After the ischemic period, heart function was significantly better in animals that were fed ad libitum than in fasted animals. Moreover, after intestinal ischemia and reperfusion, fed rats showed significantly higher levels of intestinal adenosine triphosphate and a significantly higher malondialdehyde concentration in the intestine and lung than did fasted rats. The ratio of adenosine triphosphate to adenosine diphosphate in the liver, an indicator of energy status, in fed rats was similar to that in a sham group, whereas fasted animals showed a significantly lower value.

CONCLUSIONS

Preoperative nutrition in contrast to fasting may attenuate ischemia/reperfusion-induced injury and preserve organ function in the rat.

Preoperative supplementation with a carbohydrate mixture decreases organ dysfunction-associated risk factors

BACKGROUND & AIMS

Recently, both asymmetrical dimethylarginine and IL-6 have been suggested to be associated with the induction and severity of single and multiple organ dysfunction. The aims of the present study were to elucidate if these factors were increased in an ischemia reperfusion (IR) model and whether pre-operative carbohydrate supplementation can reduce the risk factors along with the IR injury.

METHODS

One group of male Wistar rats was fasted for 16 h (water ad libitum) prior to clamping the superior mesenteric artery (IR fasted n=14). A second group had ad libitum access to a carbohydrate solution prior to clamping (IR fasted CHO group n=11). Sham-fasted animals, which only received laparotomy and no clamping, served as controls (n=4).

RESULTS

Plasma urea and ALAT activity were both increased in the IR fasted animals when compared to the sham rats (P=0.007 and P<0.02, respectively). Furthermore, it was shown that IR fasted rats had increased ADMA and IL-6 concentration in plasma when compared to sham animals (P<0.02). Moreover, the GSH level in lung was significantly decreased in the IR fasted animals (P=0.014). IR CHO supplemented showed no significant increase of ALAT activity and decrease of lung GSH. Furthermore, significantly lower plasma urea, ADMA and IL-6 concentration was seen in the IR CHO supplemented group when compared to the IR fasted rats (P=0.028, P<0.01 and P<0.02, respectively). The liver glycogen concentration in IR fasted rats was 48% of that IR rats supplemented the carbohydrate mixture.

CONCLUSION

The present rat intestinal ischemia reperfusion model not only induces organ injury indicated by the classical parameters such as plasma urea and ALAT activity, but also increased plasma IL-6 and ADMA and decreased lung GSH concentration in IR fasted rats. Pre-operative supplementation with the carbohydrate mixture significantly lowered the plasma urea, IL-6 and ADMA concentrations and maintained lung GSH concentration. This indicates that pre-operative carbohydrate supplementation reduces post-operative organ injury.

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.

A european, multicenter, observational study to assess the value of gastric-to-end tidal PCO2 difference in predicting postoperative complications

Automated online tonometry displays a rapid, semicontinuous measurement of gastric-to-endtidal carbon dioxide (Pr-etCO2) as an index of gastrointestinal perfusion during surgery. Its use to predict postoperative outcome has not been studied in general surgery patients. We, therefore, studied ASA physical status III-IV patients operated on for elective surgery under general anesthesia and a planned duration of >2 h in a European, multicenter study. As each center was equipped with only 1 tonometric monitor, a randomization was performed if more than one patient was eligible the same day. Patients not monitored with tonometry were assessed only for follow-up. The main outcome measure was the assessment of postoperative functional recovery delay (FRD) on day 8. Among the 290 patients studied, 34% had FRD associated with a longer hospital stay. The most common FRDs were gastrointestinal (45%), infection (39%), and respiratory (35%). In those monitored with tonometry (n = 179), maximum Pr-etCO2 proved to be the best predictor increasing the probability of FRD from 34% for all patients to 65% at a cut-off of 21 mm Hg (2.8kPa) (sensitivity 0.27, specificity 0.92, positive predictive value 64%, negative predictive value 70%). We conclude that intraoperative Pr-etCO2 measurement may be a useful prognostic index of postoperative morbidity.

Visceral and Renal Tissue Oxygenation During Supraceliac Aortic Crossclamping and Left Heart Bypass with Selective Organ Perfusion

INTRODUCTION

Left-heart bypass (LHB) and selective organ perfusion (SOP) are used during thoracoabdominal aortic surgery to prevent ischemic damage to the kidneys and visceral organs after supraceliac aortic crossclamping. We studied the hypothesis, in a porcine model, that despite LHB and maximal SOP, visceral and renal ischemia still occurred during surgery.

MATERIAL AND METHODS

Eleven pigs (54-70 kg) were coupled to a non-pulsatile LHB with inflow and outflow at the lower thoracic and distal infrarenal aorta, respectively. After supracoeliac and infrarenal aortic crossclamping, SOP was started using perfusion catheters. The proximal and distal mean aortic blood pressures were kept above 70 and 50 mmHg, respectively, while the mean blood pressure within the SOP system was above 60 mmHg. The visceral and renal tissue oxygenation was measured by intermittent blood gas analysis, from the portal and both renal veins. The jejunal mucosal oxygenation was measured by tonometric measurement of the luminal pCO2.

RESULTS

Measured median blood blood flow through the LHB and the SOP system were 800 and 1140 ml/min, respectively. Median blood flow prior to, and during LHB and SOP through the celiac artery, superior mesenteric artery, and left renal artery were 300 and 240, 762 and 295, and 235 and 235 ml/min, respectively. During 3 h of LHB and SOP no significant changes in the renal tissue oxygenation were noted compared with the physiological situation prior to supracoeliac aortic crossclamping and cannulation. However, in the visceral vascular bed median mixed venous oxygen saturation dropped from 79 to 63% (p<0.001), and median oxygen extraction ratio increased from 26 to 41% (p<0.001). Median tonometric measured intraluminal jejunal pCO2 increased from 9.9 to 12.15 kPa (p>0.05). During 3 h of LHB and SOP no hemolysis was detected, as there was no rise in serum LDH.

CONCLUSION

LHB and SOP preserves renal but not visceral tissue oxygenation during supraceliac aortic crossclamping and does not induce hemolysis.

Outcomes in patients with normal serum creatinine and with artificial renal support for acute renal failure developing after coronary artery bypass grafting

This retrospective study of cardiac surgical patients with normal serum creatinine who developed acute renal failure requiring artificial renal support was undertaken to (1) determine the prevalence of acute renal failure and hospital mortality in this subgroup, (2) identify the independent predictors of early mortality, and (3) determine long-term survival and prognosis.

Does off-pump CABG reduce gastrointestinal complications?

BACKGROUND

The aim of this study was to compare gastrointestinal complications and associated risk factors among patients undergoing cardiac surgery using off- and on-pump revascularization techniques.

METHODS

A total of 1146 adult patients who underwent coronary artery surgery during a 6-year period were evaluated retrospectively. Group 1 consisted of 546 patients operated using off-pump techniques and group 2 consisted of 600 cases operated with cardiopulmonary bypass. Patients were compared and evaluated for gastrointestinal complications and possible associated risk factors using univariate and multivariate logistic regression analysis.

RESULTS

Overall mortality was 1.6% in group 1 and 2.2% in group 2 (p = 0.523). Mortality due to gastrointestinal complications was 38.5% and 35.7% respectively in group 1 and group 2. The mean EuroSCORE value was 5.1 +/- 2.8 in group 1 and 3.8 +/- 2.4 in group 2 (p < 0.001). The most common gastrointestinal complication in the off-pump group was gastrointestinal bleeding. The leading complication in group 2 was intestinal ischemia.

CONCLUSIONS

The incidence rates of gastrointestinal complications were similar in the on- and off-pump coronary artery bypass groups, the type of gastrointestinal complications, however, was different. Mortality rate due to these complications was also similar and remained high, regardless of the type of surgery. Cardiopulmonary bypass did not emerge as a risk factor for gastrointestinal complications, but prolonged cardiopulmonary bypass (longer than 98 minutes) resulted in a high incidence of such complications. Old age and advanced arteriosclerosis emerged as risk factors in both groups resulting in gastrointestinal complications suggesting the ischemic nature of the injury.

Gut in diseases: Physiological elements and their clinical significance

The intestinal barrier function of GI tract is very important in the body except for the function of digestion and absorption. The functional status of gut barrier basically reflects the stress severity when body suffers from trauma and various stimulations. Many harmful factors such as drugs, illnesses, trauma and burns can damage the gut barrier, which can lead to the barrier dysfunction and bacterial/endotoxin translocation. The paper discusses and reviews the concepts, anatomy, pathophysiology of gut barrier and its clinical relations.

Gastric emptying in mechanically ventilated critically ill patients: effect of neuromuscular blocking agent

OBJECTIVE

To assess gastrointestinal function in critically ill patients receiving muscle relaxant and to test clinical tolerance to enteral nutrition.

DESIGN AND SETTING

Prospective study in an intensive care unit.

PATIENTS

20 critically ill patients requiring sedation with muscle relaxant to obtain adequate mechanical ventilation.

MEASUREMENTS AND RESULTS

Patients were randomly selected to receive infusions of opioid sedation during the first session (session 1) and the same sedation with muscle relaxation (cisatracurium) during the second session (session 2). Gastric emptying was assessed by the paracetamol absorption technique. Following the paracetamol absorption 200 ml enteral feed was given, and the residual gastric volume was measured 1 and 2 h after feeding. The maximum plasma concentration (Cmax) was 14 mg/l (range 5-26) when patients received sedation, and 12 mg/l (range 5-30) when they received muscle relaxant. The target time for reaching the maximum plasma concentration (Tmax) was 30 min (range 20-60) and 35 min (range 20-60), respectively, in sessions 1 and 2. There was no significant difference between the two session as regards Tmax, Cmax, or AUC(0-120). The residual volumes were 110+/-65 ml (H1) and 95+/-76 ml (H2) during session 1 and 125+/-85 ml (H1) and 105+/-90 ml (H2) during session 2.

CONCLUSIONS

Enteral feeding is one of the most effective methods of supporting nutritional needs in the critically ill patient. We conclude that in critically ill patients requiring sedation gastric emptying is not improved by neuromuscular blocking agent.

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Gastric hypercarbia and adverse outcome after cardiac surgery

OBJECTIVE

It has been postulated that splanchnic ischemia, as manifested by gastric hypercarbia, helps to trigger excessive systemic inflammation, which has been linked to the development of adverse postoperative outcome. This study examined whether gastric PCO(2) values are associated with adverse outcome in cardiac surgical patients.

DESIGN AND SETTING

Prospective cohort study in a tertiary-care hospital.

PATIENTS

43 patients undergoing elective cardiac surgery.

INTERVENTIONS

Simultaneous measurements of gastric PCO(2) (using automated air tonometry) and arterial PCO(2) were obtained at the beginning and end of surgery. The difference (gap) between regional PCO(2) and arterial PCO(2) (corrected for temperature) was calculated. Adverse outcome was defined as in-hospital death or prolonged (>10 days) postoperative hospitalization.

MEASUREMENTS AND RESULTS

Fourteen patients fulfilled the predefined definition for adverse outcome. Postoperative ICU stay and postoperative hospital length of stay were significantly longer in these patients. At the end of surgery gastric minus arterial PCO(2) gap was significantly larger in patients with adverse outcome. Global hemodynamic and perfusion related variables were not associated with adverse outcome (cardiac index, mean arterial pressure, mixed venous oxygen saturation, arterial lactate, arterial base excess).

CONCLUSIONS

Gastric minus arterial PCO(2) gap after surgery is larger in patients with adverse postoperative outcome, which supports the theory that gastrointestinal reduced perfusion is relevant to the pathogenesis of postoperative morbidity.

Usefulness of continuous air tonometry for evaluation of splanchnic perfusion during cardiopulmonary bypass

Although gastric mucosal tonometry has been reported as a useful method to assess splanchnic perfusion during cardiovascular surgery, the conventional discontinuous method of tonometry (saline tonometry) was cumbersome and prone to systematic errors. A new automated system of air tonometry (Tonocap; Datex Ohmeda, Helsinki, Finland) allows for frequent (every 10 minutes) measurement of gastric regional CO2 (PrCO2) and may be more suitable as a monitoring system in cardiac patients. We evaluated the usefulness of continuous air tonometry as a marker of splanchnic perfusion during cardiopulmonary bypass (CPB). In 19 patients (53-79 years, mean 63 years) who underwent cardiovascular surgery under standard CPB with mild hypothermia (32 degrees C) from January 2001 to May 2002, the PrCO2 and calculated intramucosal pH (pHi) of gastric tonometry was monitored using Tonocap, and their relation to postoperative visceral organ function was evaluated. The pHi significantly increased after initiation of CPB from 7.32 +/- 0.07 to 7.43 +/- 0.10 (p < 0.05) and then consistently decreased in all patients to 7.39 +/- 0.09 at the end of CPB. The value of PrCO2 significantly (p < 0.01) correlated with the value of pHi. The lowest value of pHi during CPB was significantly related to blood urea nitrogen (r = -0.75, p < 0.05), serum creatinine (r = -0.78, p < 0.05), creatinine clearance (r = 0.68, p < 0.05) on postoperative day 1, and blood urea nitrogen (r = -0.84, p < 0.01) on day 3. In contrast, arterial blood lactate level, venous oxygen saturation, and routinely measured hemodynamics (e.g., pump flow, arterial pressure) during CPB were unrelated to the postoperative visceral organ function. These results suggest that continuous monitoring of gastric regional CO2 and pHi by air tonometry system is useful for the evaluation of splanchnic perfusion during CPB and may contribute to improve CPB technique by allowing the early detection of visceral malperfusion.

Mesenteric complications after hypothermic cardiopulmonary bypass with cardiac arrest: underlying mechanisms

The aim of this study was to determine the pathophysiological mechanisms of postcardiopulmonary bypass (CPB) intestinal dysfunction using an in vivo canine model of extracorporeal circulation. Six dogs underwent a 90 min hypothermic CPB with continuous monitoring of mean arterial blood pressure (MAP) and mesenteric blood flow (MBF). Reactive hyperemia and vasodilator responses of the superior mesenteric artery to acetylcholine and sodium nitroprusside were determined before and after CPB. Mesenteric lactate production, glucose consumption, creatine kinase (CK) release and venous free radicals were determined. CPB induced a significant fall (p < 0.05) in MAP and MBF. After CPB, reactive hyperemia (-26 +/- 15% versus -53 +/- 2%, p < 0.05) and the response to acetylcholine (-42 +/- 9 versus -55 +/- 6%, p < 0.05) were significantly decreased. Reperfusion increased lactate production (0.8 +/- 0.09 mmol/L versus 0.4 +/- 0.18, p < 0.05) and the CK release (446 +/- 98 U/L versus 5 +/- 19 U/L, p < 0.01). Endothelial dysfunction, conversion from aerobic to anaerobic metabolism, and intestinal cell necrosis seem to be responsible for intestinal complications associated with CPB.

Evodia rutaecarpa protects against circulation failure and organ dysfunction in endotoxaemic rats through modulating nitric oxide release

Using a rat model of septic shock we studied the effects of Evodia rutaecarpa, a Chinese herbal medicine with antimicrobial and anti-inflammatory activity, on haemodynamic parameters, biochemical markers of organ function and nitric oxide (NO) production. Anaesthetized rats challenged with a high dosage of endotoxin (Escherichia coli lipopolysaccharide; LPS; 50 mg kg(-1), i.v.) for 6 h showed a severe decrease in mean arterial pressure. This was accompanied by delayed bradycardia, vascular hyporeactivity to phenylephrine and increase in plasma levels of lactate dehydrogenase, aspartate aminotransferase, bilirubin and creatinine, as well as NOx (NO2- plus NO3-). Pretreatment with ethanol extract of E. rutaecarpa (25, 50 and 100 mg kg(-1), i.v.), 1 h before LPS, dose-dependently prevented the circulation failure, vascular hyporeactivity to phenylephrine, prevented liver dysfunction and reduced the NOx over-production in plasma in endotoxaemic rats. A selective inducible NO-synthase (iNOS) inhibitor, aminoguanidine (15 mg kg(-1), i.v.), also effectively ameliorated the above pathophysiological phenomenon associated with endotoxaemia so that the normal condition was approached. Endotoxaemia for 6 h resulted in a significant increase in iNOS activity in the liver homogenate, which was attenuated significantly by E. rutaecarpa pretreatment. In summary, E. rutaecarpa, at the dosages used, exerted these beneficial effects probably through inhibition of iNOS activity and subsequent modulation of the release of NO. These significant results may offer E. rutaecarpa as a candidate for the treatment of this model of endotoxaemia.

The Use of Metoclopramide in Ileus: A Look at Duration of Therapy

Purpose

The authors conducted a retrospective chart review to determine if metoclopramide was being used properly for ileus and if it caused any adverse effects.

Methods

All adult patients admitted to the institution's ICUs between November 10, 2000 and January 31, 2001 were evaluated for enrollment. Data was obtained from medication administration records, patient flow sheets, the computer-based laboratory and report systems, and a database of adverse drug events. Bowel movements were used to assess effectiveness. The primary end-point was the length of time metoclopramide was continued after the first bowel movement. A secondary endpoint was the occurrence of any adverse effects related to metoclopramide administration.

Results

There were a total of 32 patients who received metoclopramide for ileus during the time period studied. The average number of days people received metoclopramide was 11.5 ± 7.3 days. The mean time to first bowel movement was 1.7 ± 1.4 days. Patients had therapy continued after first bowel movement for an average of 10.7 ± 7.1 days. Extrapyramidal symptoms possibly occurred in 3% of the patients.

Conclusion

The results suggest that metoclopramide was used for the treatment of ileus in ICU patients for prolonged periods of time. This overuse may place patients at risk for adverse events and may also occur at other institutions.

Dopexamine attenuates microvascular perfusion injury of the small bowel in pigs induced by extracorporeal circulation

BACKGROUND

Cardio-thoracic surgery with the use of extracorporeal circulation may lead to an impairment of splanchnic perfusion. The aim of this study was to investigate the effect of dopexamine on gastrointestinal microvascular perfusion failure due to extracorporeal circulation.

METHODS

Twenty landrace pigs served as laboratory animals. A loop of the terminal ileum was exteriorized for microscopic observation. In 13 animals a partial left-heart bypass (pLHB), with a non-pulsatile pump flow of approximately 50% of the cardiac output, was established for 2 h. Seven animals received a continuous i.v. infusion of 3 micrograms kg-1 min-1 dopexamine from the beginning of pLHB to the end of the experiment. Seven sham-operated animals served as controls. The microcirculatory network was analysed by means of intra-vital microscopy prior to, during pLHB, and 2 h after bypass.

RESULTS

Despite normal haemodynamics measured by arterial pressure and cardiac output, pLHB led to significant impairment of microvascular perfusion characterized by arteriolar vasoconstriction, reduction of functional capillary density (FCD) to 30% 2 h after weaning off bypass and diminished blood-cell velocities in submucous venules. Dopexamine attenuated this perfusion impairment, preventing arteriolar vasoconstriction. FCD remained normal.

CONCLUSION

Our data demonstrate that treatment with the vasoactive drug dopexamine leads to a significant reduction of the perfusion injury of the small bowel.

Special feature: exploring the benefits and myths of enteral feeding in the critically ill

Patients in the intensive care unit setting have been nutritionally deprived for various reasons. Many patients who are critically ill cannot absorb nourishment by traditional routes. Enteral feeding should be considered for all patients who cannot meet caloric needs. There are many benefits to enteral feeding such as decreased infection, rapid wound healing, and decreased length of stay and mortality. Many critical care nurses subscribe to myths for not feeding their patients. The myths for not feeding critically ill patients involve gut motility, feeding residuals, and patient positioning. There is significant evidence both to support nutrition as integral to recovery from a critical illness and to suggest that enteral feeding is efficient and effective at providing nutrition.

No effect of preoperative selective gut decontamination on endotoxemia and cytokine activation during cardiopulmonary bypass: a randomized, placebo-controlled study

BACKGROUND

Cardiopulmonary bypass predisposes the splanchnic region to inadequate perfusion and increases in gut permeability. Related to these changes, circulating endotoxin has been shown to rise during cardiac surgery, and may contribute to cytokine activation, high oxygen consumption, and fever ("postperfusion syndrome"). To a large extent, free endotoxin in the gut is a product of the proliferation of aerobic gram-negative bacteria and may be reduced by nonabsorbable antibiotics.

OBJECTIVE

To evaluate the effect of preoperative selective gut decontamination (SGD) on the incidence of endotoxemia and cytokine activation in patients undergoing open heart surgery.

DESIGN

Prospective, randomized, placebo-controlled double-blind trial.

SETTING

Tertiary-care university teaching hospital.

INTERVENTION

Preoperative administration for 5 to 7 days of oral nonabsorbable antibiotics (polymyxin B and neomycin) vs. placebo. The efficacy of SGD was assessed by culture of rectal swabs.

PATIENTS

Forty-four patients (median age 65 yrs, 29 males) were included in a pilot study to establish the sampling points of perioperative measurements. Seventy-eight consecutive patients (median age 65 yrs, 55 males) were enrolled for the prospective study; of these, 51 were randomly allocated to take SGD (n = 24) or placebo (n = 27); 27 were included in a control group (no medication).

MEASUREMENTS AND RESULTS

SGD but not placebo effectively reduced the number of rectal swabs that grew aerobic gram-negative bacteria (27% vs. 93%, respectively; p < .001). SGD did not affect the occurrence of perioperative endotoxemia, nor did it reduce the tumor necrosis factor-alpha, interleukin-10, or interleukin-6 concentrations (p > .20), as determined before surgery, upon aorta declamping, 30 mins into reperfusion, or 2 hrs after surgery. Also, SGD did not alter the incidence of postoperative fever or clinical outcome measures such as duration of artificial ventilation and intensive care unit and hospital stay.

CONCLUSION

SGD effectively reduces the aerobic gram-negative bowel flora in cardiac surgery patients but fails to affect the incidence of perioperative endotoxemia and cytokine activation during cardiopulmonary bypass and the occurrence of a postperfusion syndrome.

Malnutrition, nutritional indices, and early enteral feeding in critically ill children

We measured the incidences of protein and fat depletions and the frequencies of acute and chronic protein-energy malnutrition during stress states in children and investigated the influence of early enteral feeding on nutrition indices and acute-phase proteins. Seventy-one, consecutively enrolled, critically ill children received early enteral feeding (energy intakes equal to 0.50, 1, 1.25, 1.5, and 1.5 of the predicted basal metabolic rates on days 1 through 5, respectively) through nasogastric tubes. On the first day of the study, 16.7% of the patients already were depleted of protein and 31% of fat stores. Overall, 16.9% were at risk for chronic protein-energy malnutrition and 21.1% for acute protein-energy malnutrition, whereas 4.2% and 5.6% already had chronic and acute, respectively protein-energy malnutrition. Only 22.7% of patients without protein deficiencies versus 37% of those at risk or already deficient developed multiple-organ system failure. Transferrin and prealbumin levels improved at the end of the period of early enteral feeding (187 +/- 6.6 versus 233 +/- 7 mg/dL, P < 0.0001; 15.1 +/- 2 versus 21.9 +/- 2.9 mg/dL, P < 0.0001; respectively); survivors had higher prealbumin levels than non-survivors (22.3 versus 15.5 mg/dL). With logistic regression analysis, only repleted energy, not anthropometric or nutrition indices, was independently associated with survival (P = 0.05). These results reinforce the observation that critically ill children are at risk for fat or protein depletion and development of malnutrition, which is associated with increased morbidity and mortality. We conclude that early enteral nutrition improves nutrition indices and outcomes.

Effectiveness and safety of a protocol for promotion of early intragastric feeding in critically ill children

OBJECTIVES: To investigate the feasibility, adequacy, and efficacy of early poststress intragastric feeding (EPIGF) in critically ill children. DESIGN: A prospective clinical study. SETTING: Pediatric intensive care unit in a tertiary care children's hospital. PATIENTS: Seventy-one consecutively enrolled critically ill children requiring prolonged mechanical ventilation. INTERVENTIONS: Full-strength intragastric tube feedings (Nutrison Pediatric, Standard) were initiated within 12 hrs of the study-entry event. Enteral feedings were advanced to a target volume of energy intake = 1/2, 1, 5/4, 6/4, and 6/4 of the predicted basal metabolic rate (PBMR) on days 1-5, respectively. MEASUREMENTS AND MAIN RESULTS: Nutritional status by the caloric intake, recommended dietary allowances, PBMR, predicted energy expenditure (PEE), anthropometry, and clinical indices were evaluated on days 1 and 5. Safety was assessed by the clinical course of disease, laboratory findings, and occurrence of complications. Success was determined by accomplishment of the PEE target. The early success rate was 94.4% and predicted late enteral feeding success accurately (p =.0001). Caloric intake approached PBMR the second day (43 +/- 1.7 kcal/kg/day vs. 43.2 +/- 1.1 kcal/kg/day) and PEE the fifth day (66.2 +/- 2.7 kcal/kg/day vs. 67.7 +/- 6.4 kcal/kg/day). Multivariate stepwise regression analysis showed that poor outcome and a high Therapeutic Intervention Scoring System score correlated with failure of EPIGF (p <.0001). Patients who succeeded EPIGF had significantly higher myocardial ejection (65% vs. 43%; p <.0001) or shortening fractions (34% vs. 20%; p =.0001) on day 1 than those who failed. Patients tolerated EPIGF well; 9.9% developed nosocomial pneumonia, 5.6% developed diarrhea, and 8.5% needed treatment with cisapride because of a delay of gastric emptying. The mortality rate (5.6%) was different between initial and final success and failure groups (p <.0001) and was lower than predicted by the admission severity scores (12% +/- 2%). CONCLUSIONS: This study showed that increases of caloric intake during the acute phase of a critical illness are well tolerated and may approach PBMR by the second day and PEE by the fourth day in critically ill children. Caloric intake lower than PBMR is associated with higher mortality and morbidity rates.

Incidence and predictors of ARDS after cardiac surgery

BACKGROUND

Severe pulmonary injury with the development of ARDS is a potential complication of cardiac surgery and cardiopulmonary bypass (CPB).

STUDY OBJECTIVES

This retrospective, case-control study was designed to determine the incidence and mortality of ARDS after cardiac surgery and CPB, as well as to identify preoperative and perioperative predisposing factors of this complication.

METHODS

Of 3,278 patients who underwent cardiac surgery and CPB between January 1995 and December 1998, 13 patients developed ARDS during the postoperative period. Each patient was matched with four or five control subjects who had the same type of surgery on the same day but did not develop postoperative respiratory complications.

RESULTS

The incidence of ARDS was 0.4%, with an ARDS mortality of 15%. In the ARDS group, 38% had previous cardiac surgery, as compared to 3.5% in the control group (p < 0.002). During the postoperative period, ARDS patients received more blood products (4 +/- 5 vs 2 +/- 3; p < 0.01) and developed shock more frequently (31% vs 5%; p < 0.02) than patients in the control group. Multivariate regression analysis identified previous cardiac surgery, shock, and the number of transfused blood products as significant independent predictors for ARDS, with odds ratios of 31.5 (p = 0.015), 10.8 (p = 0.03), and 1.6 (p = 0.03), respectively.

CONCLUSIONS

ARDS following cardiac surgery and CPB was a rare complication that carried a 15% mortality rate. Previous cardiac surgery, shock, and number of blood products received are important predicting factors for this complication.