The acute surgical abdomen after cardiac surgery involving extracorporeal circulation

Gastrointestinal bleeding risk factors in type A aortic dissection post-aortic arch replacement

Background

Gastrointestinal bleeding (GIB) is a notable complication in patients diagnosed with aortic dissection (AD). We evaluated the outcomes and identified the risk factors associated with GIB in patients with AD.

Methods

A retrospective case-control study was conducted on patients diagnosed with type A aortic dissection (TAAD) who underwent total aortic arch replacement (TAAR) at our institution from July 2021 to July 2023. Comprehensive clinical data, laboratory findings, and imaging results were meticulously gathered and analyzed to identify potential risk factors linked to GIB in this patient cohort.

Results

Of the 198 AD patients who underwent TAAR, 38 (19.2%) developed postoperative GIB (GIB group), with a median interval of 7 days between surgery and bleeding onset. The GIB group exhibited significantly higher mortality (26.3% vs. 3.1%, P<0.001), prolonged intensive care unit (ICU) stay {15 [interquartile range (IQR), 8-25] vs. 7 (IQR, 5-12) days, P<0.001}, and extended duration of ventilation [168 (IQR, 120-372) vs. 71 (IQR, 34-148) hours, P<0.001] compared to the control group (n=160, 80.8%). Logistic regression analysis identified age >54 years [odds ratio (OR): 3.529], intraoperative red blood cell (RBC) transfusion >600 mL (OR: 3.865), and concomitant celiac trunk and superior mesenteric artery (SMA) hypoperfusion (OR: 15.974) as independent risk factors for GIB in AD patients.

Conclusions

GIB subsequent to TAAR in AD patients is linked to adverse prognosis. Factors such as advanced age, extensive intraoperative transfusion, and gastrointestinal (GI) perfusion abnormalities may heighten the risk of GIB in this patient population.

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.

Gastrointestinal complications after cardiac surgery: 10-year experience of a single Australian centre

BACKGROUND

Gastrointestinal (GI) complications after cardiac surgery are uncommon, but are associated with high morbidity and mortality as well as significant hospital resource utilization.

METHODS

We analysed a prospectively collected database containing all adult cardiac surgery procedures performed from July 2001 to March 2011 at Monash Medical Centre and Jessie McPherson Private Hospital. Patients with post-operative GI complications were compared to patients without GI complications who were operated in the same period.

RESULTS

The incidence of GI complications was 1.1% (61 out of 5382 patients) with an overall 30-day mortality of 33% (versus 3% in the non-GI complication group). The most common complications were GI bleeding, gastroenteritis and bowel ischaemia. Patients who had GI complications were significantly older, had higher incidence of renal impairment, chronic lung disease and anticoagulation therapy and were more likely to be in cardiogenic shock. Emergency procedures, combined coronary artery bypass grafting and valve surgery and aortic dissection cases were more common in the GI complication group. The GI complication group also had higher incidence of return to theatre, renal failure, stroke, septicaemia and multi-organ failure.

CONCLUSIONS

GI complications after cardiac surgery remain an uncommon but dreadful complication associated with high mortality. Our findings should prompt a high degree of clinical vigilance in order to make an early diagnosis especially in high risk patients. Further studies aiming to identify independent predictors for GI complications after cardiac surgery are warranted.

Bedside diagnostic laparoscopy for critically ill patients: a retrospective study of 62 patients

BACKGROUND

Bedside diagnostic laparoscopy has an important role of diagnosing acute abdomen in critically ill patients hospitalized in the intensive care unit (ICU). Delayed diagnosis of intraabdominal pathology increases the morbidity and mortality rates for these patients, whose clinical signs often are absent due to analgesic medication and sedation.

METHODS

In this retrospective study performed from January 2007 to December 2009, 62 consecutive ICU patients whose blood test results showed them to be hemodynamically unstable underwent bedside diagnostic laparoscopy. The inclusion criteria specified clinically suspected acute cholecystitis, unknown sepsis, acidosis with a high level of lactate, elevated lab tests (white blood cell count, bilirubin, lactic dehydrogenase, creatine phosphokinase, gamma glutamyl transferase [γGT]), and acute anemia with suspected intraabdominal bleeding. The major contraindications to bedside diagnostic laparoscopy were coagulopathy, endocranic hypertension, and heart failure. Patients with a clear indication for an open surgical procedure were excluded from the study.

RESULTS

Of the 62 patients who underwent bedside diagnostic laparoscopy, 43 (69.3%) had positive findings and 29 (46.7%) had acute acalculous cholecystitis. The mean operation time was 38 min, and no procedure-related deaths occurred. The procedure was performed for postsurgery patients, especially after cardiac operations, and for trauma or septic patients. Respiratory and hemodynamic parameters were monitored before, during, and after the procedure.

CONCLUSIONS

As a minimally invasive procedure, bedside diagnostic laparoscopy can be performed in the ICU for hemodynamically unstable patients. It is safe procedure with high diagnostic accuracy for acute intraabdominal conditions that avoids negative laparotomies for unstable patients. The bedside diagnostic laparoscopy procedure is not performed widely, and prospective studies are needed to better evaluate outcome and advantages for critically ill patients.

Postoperative Care of the Cardiac Surgical Patient

The subspecialty of interventional cardiology began in 1977. Since then, the discipline of interventional cardiology has matured rapidly, particularly with regards to ischemic heart disease. As a result, more patients are undergoing percutaneous catheter interventional therapy for ischemic heart disease and fewer patients are undergoing surgical myocardial revascularization. Those patients referred for surgical revascularization are generally older and have more complex problems. Furthermore, as the population ages more patients are referred to surgery for valvular heart disease. The result of these changes is a population of surgical patients older and sicker than previously treated.

Diagnosis and outcome from suspected mesenteric ischaemia following cardiac surgery

A three-year retrospective chart review was undertaken of all post-cardiothoracic ICU patients who underwent laparotomy for suspected mesenteric ischaemia, or who had the diagnosis confirmed at post mortem. The aim was to compare the clinical and diagnostic characteristics of cardiothoracic patients with suspected mesenteric ischaemia with patients who had a confirmed diagnosis. There were 3024 admissions to the cardiothoracic ICU over the three-year period. Twenty-six laparotomies were performed for suspected mesenteric ischaemia and 15 were positive for mesenteric ischaemia. The overall incidence of mesenteric ischaemia was 17/3024 (0.6%). Mortality for patients with mesenteric ischaemia was 13/17 (76%). Ischaemia was limited to a single segment of bowel in the four survivors. Mortality in patients who had a negative laparotomy for suspected mesenteric ischaemia was 7/11 (64%), attributable to cardiovascular failure (2/11) and multi-organ dysfunction syndrome (5/11). No clinical, biochemical or haematological test was discriminatory for mesenteric ischaemia. In patients with proven ischaemia, 7/13 plain abdominal radiographs were positive for ischaemia and 7/7 radiographs were negative for ischaemia in patients with no ischaemia (P = 0.05, PPV 1.0, NPV 0.5, sensitivity 54%, specificity 100%). Neither routine clinical investigations nor plain abdominal radiography reliably diagnose mesenteric ischaemia when the diagnosis is suspected clinically. Early laparotomy is recommended in these patients and further investigation may delay this procedure unnecessarily. The presence of mesenteric ischaemia identifies a cohort of patients with high mortality.

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.

Accuracy of diagnostic laparoscopy for early diagnosis of abdominal complications after cardiac surgery

BACKGROUND

In the early postoperative period after major cardiac surgery using extracorporal circulation, abdominal complications can have serious consequences with a mortality rate of up to 70%. Early diagnosis and the timely institution of therapy are the most important factors to improve the outcome; however, clinical evaluation of the abdomen is difficult in these patients. Diagnostic laparoscopy is a minimally invasive procedure with low procedure-associated morbidity, even in critically ill patients. The aims of our study were to investigate the safety of laparoscopy in critically ill patients suspected to have intraabdominal pathology following cardiac surgery and to evaluate the accuracy of diagnostic laparoscopy compared to laparotomy in this setting.

METHODS

A total of 17 patients were included (13 male, four female, age 52-80 years) in the early (3-30 days) postoperative period after cardiac surgery using extracorporal circulation (10 ACVB, four valve replacement, one aorto-coronary-venous-bypass (ACVB)+ valve replacement, two cardiac transplantation). Clinical and laboratory findings included distended abdomen (17 of 17), elevated white blood cells (12 of 17), elevated C-reactive protein (CRP) (13 of 17), and elevated lactate levels (11 of 17). The decision to perform laparotomy was taken in all patients on the basis of their clinical condition. Diagnostic laparoscopy was always performed immediately before laparotomy. The laparoscopic findings were then compared to the laparotomy findings.

RESULTS

In one patient, laparoscopy showed no abnormal findings, this was confirmed on laparotomy. Five patients were found to have massive distension of the large bowel without ischemia on both laparoscopy and laparotomy. Colonic ischemia of the right hemicolon was found laparoscopically in six patients, which was confirmed in all cases by open resection and histological workup. Three patients suffered from acute cholecystitis, which was correctly diagnosed by laparoscopy in all cases. In one patient, laparoscopy revealed fibrinous peritonitis without other findings. Open exploration failed to identify the cause of the peritonitis in this patient. Laparoscopy showed no pathological findings in one patient, but laparotomy then revealed necrotizing pancreatitis confined to the lesser sac. There was one laparoscopy-associated intraoperative complication (6%) in this series.

CONCLUSIONS

Diagnostic laparoscopy is a minimally invasive procedure that can be performed at low intraoperative risk in critically ill patients and has a high sensitivity (94%) for the correct diagnosis of intraabdominal complications after major cardiac surgery. These results suggest that bedside laparoscopy should be considered for all patients with equivocal abdominal symptoms in this setting.

Unexpected subdiaphragmatic findings on CT of the chest in septic patients after cardiac surgery

AIM

to draw the attention to upper abdominal abnormalities, which may be revealed incidentally in patients referred for a chest computed tomography (CT) after cardiac surgery.

MATERIALS AND METHODS

We reviewed prospectively and retrospectively the CT results of all patients referred for a chest CT, with suspected sternal infection or for other reasons, after cardiac surgery, to assess possible upper abdominal disease as visualized on lower cuts of the chest CT with abdominal windows.

RESULTS

Out of a total of 205 patients in the study 39 (19%) had unexpected abdominal abnormalities. The organs involved in decreasing order of frequency were the spleen (n = 18), gallbladder (n = 15), pancreas (n = 9), kidneys (n = 6) and bowel (n = 3). Many patients had involvement of more than one organ. The lesions were mainly ischaemic and/or infectious in origin. These findings led to interventional procedures in 13 (33%) of the patients with a good outcome.

CONCLUSIONS

We found a relatively high prevalence of abdominal abnormalities on CT of the chest in patients referred with suspected thoracic problems after cardiac surgery. Major findings on CT led to changes in the management of these patients. We recommend therefore viewing lung bases with abdominal windows as well as adding sections through the upper abdomen in patients who are referred for a chest CT after cardiac surgery with suspected thoracic problems.

Visceral Ischemia after Cardiopulmonary Bypass

The diagnosis and management of gastrointestinal complications associated with cardiopulmonary bypass is often hindered by a complicated clinical picture and equivocal examination. To better define the incidence, risk factors, and mortality, we reviewed the records of all patients undergoing cardiopulmonary bypass from 1988 through 1996. The database for this study comprised 14,521 patients who underwent cardiac surgery. The patients (543) with gastrointestinal complications were identified, and those with major complications (166) were individually reviewed. Major complications included pancreatitis, gastritis, laparotomy, gastric ulcer, cholecystitis, colonic perforation, gastrointestinal bleeding, diverticulitis, bowel obstruction, perforation, and visceral ischemia. Our results were the following. 1) Gastrointestinal complications were noted in 3.7 per cent (543) of patients with major complications occurring in 1.2 per cent. In 166 patients, 187 major complications were noted. 2) Visceral ischemia, an infrequent but usually fatal (71%) complication, occurred in 24 (0.17%). 3) Of the ischemic events, 83 per cent (20 of 24) affected the bowel; with the colon involved 80 per cent of the time (16 of 20). 4) Patients with visceral ischemia were more likely to be female (relative risk 2.1), have longer pump times (92.2 versus 74.2), have cardiac procedures other than coronary artery bypass graft (relative risk 2.6), and have end-stage renal disease (relative risk 16.7). We conclude that, given the incidence and mortality related to visceral ischemia, especially to the colon, patients with risk factors (end-stage renal disease, female sex, non-coronary artery bypass graft, and longer pump times) should undergo routine endoscopic examination of the colon early after bypass and when clinically indicated thereafter.

The significance of hyperamylasaemia after colonic resection

OBJECTIVE

Colonic resection may be complicated by prolonged post-operative paralytic ileus. Post-operative hyperamylasaemia and pancreatitis may sometimes follow abdominal surgery or occasionally trauma. Post-operative ileus seen after colectomy may be secondary to unrecognized pancreatitis and hyperamylasaemia. The aims of this study were to identify the incidence of hyperamylasaemia after colonic resection, to investigate the effect of hyperamylasaemia on post-operative intestinal function and to correlate any changes with extent of colorectal resection.

PATIENTS AND METHODS

The serum amylase was determined prospectively in a consecutive series of 150 patients who underwent elective colorectal resection. Serum amylase was measured before surgery and post-operatively until it returned to within the normal range.

RESULTS

Hyperamylasaemia occurred in 28 patients (18.7%) after colorectal surgery. Serum amylase levels returned to normal in all but seven patients (4.7%) by the second post-operative day. The development of hyperamylasaemia did not adversely influence the post-operative course. Both groups of patients had similar restoration of intestinal function and were discharged home on equivalent days. Ligation of the middle colic artery alone was found to be significantly associated with hyperamylasaemia by multivariate stepwise logistic regression analysis.

CONCLUSION

Twenty-eight out of 150 patients who underwent colorectal resection developed hyperamylasaemia after surgery. The incidence was highest in patients with middle colic artery ligation. The development of post-operative hyperamylasaemia does not seem to influence adversely the post-operative course in this series.

The acute abdomen in the critically ill patient

The critically ill patient with an acute abdomen represents a great challenge for the surgeon. The physiologic derangement that is associated with the critically ill state both fuels and is fueled by acute abdominal processes. Improvements in critical care and cardiopulmonary bypass technique have allowed for a group of patients to evolve that are susceptible to the complications of prolonged flow states. This article focuses on the abdominal consequences of support of the critically ill patient, as well as, the diagnostic and therapeutic options that are available to treat these patients.

Determinants of mortality and multiorgan dysfunction in cardiac surgery patients requiring prolonged mechanical ventilation

OBJECTIVES

To identify characteristics associated with mortality and the development of multiorgan dysfunction in patients who had undergone cardiac surgery and required prolonged mechanical ventilation, ie, > 48 h.

DESIGN

A prospective cohort study.

SETTING

Barnes Hospital, St. Louis, an academic tertiary care center.

PATIENTS OR OTHER PARTICIPANTS

A total of 107 consecutive patients undergoing cardiac surgery and requiring prolonged mechanical ventilation.

INTERVENTIONS

Prospective patients surveillance and data collection.

MAIN OUTCOME MEASURES

ICU mortality and multiorgan dysfunction.

RESULTS

Among 472 consecutive patients admitted to the cardiac surgery ICU following surgery, 107 (22.7%) required prolonged mechanical ventilation. Twenty-one of these patients (19.6%) died during their hospitalization. In a logistic-regression analysis, the development of an organ system failure index (OSFI) of 3 or greater was the only characteristic independently associated with ICU mortality (p < 0.001). The occurrence of an antibiotic-resistant infection (adjusted odds ratio [AOR] = 6.1, 95% confidence interval [CI] = 2.5 to 14.6 p = 0.006), an aortic cross-clamp time equal to or greater than 1.25 h (AOR = 3.9, CI = 2.3 to 6.8, p = 0.016), the development of ventilator-associated pneumonia (AOR = 3.6, CI = 2.4 to 5.3, p < 0.001), and an APACHE III score equal to or greater than 30 (AOR = 3.1, CI = 1.8 to 5.3, p = 0.036) were independently associated with the development of an OSFI of 3 or greater.

CONCLUSIONS

These data confirm that acquired multiorgan dysfunction is the best predictor of mortality in patients requiring prolonged mechanical ventilation following cardiac surgery. Additionally, they identify potential determinants of multiorgan dysfunction and suggest possible interventions for its reduction in this patient population.

General surgical complications can be predicted after cardiopulmonary bypass

OBJECTIVE

The authors review the general surgical complications of cardiopulmonary bypass, including newer procedures such as heart and lung transplantation, to identify patients at higher risk.

SUMMARY BACKGROUND DATA

Although rare, the general surgical complications of cardiopulmonary bypass are associated with high mortality. The early identification of patients at increased risk for these complications may allow for earlier detection and treatment of these problems to reduce mortality.

METHODS

A retrospective review was performed of 1831 patients undergoing cardiopulmonary bypass from 1991 to 1993. This was done to identify factors that significantly contributed to an increased risk of general surgical complications.

RESULTS

Factors associated with an increased risk of general surgical complications included prolonged cardiopulmonary bypass (p < 0.005) and intensive care unit stay (p < 0.002), occurrence of arrhythmias (p < 0.001), use of inotropic agents (preoperatively or postoperatively p < 0.001), insertion of the intra-aortic balloon pump (preoperatively p < 0.005, postoperatively p < 0.001), use of steroids (p < 0.001), and prolonged ventilator support (p < 0.001). Multivariate analysis identified use of the intra-aortic balloon pump (p < 0.001) as the strongest predictor of the general surgical complications of cardiopulmonary bypass. A variety of factors not contributing significantly to an increased risk also were identified.

CONCLUSIONS

Factors indicative of or contributing to periods of decreased end-organ perfusion appear to be significantly related to general surgical complications after cardiopulmonary bypass.

Determinants of outcome for patients in the medical intensive care unit requiring abdominal surgery: a prospective, single-center study

OBJECTIVE

To identify objective factors, available at the time of surgical evaluation, associated with outcome for patients in the medical ICU undergoing abdominal surgery.

DESIGN

Single-center, prospective observational study.

SETTING

An academic tertiary care center.

PATIENTS

The study included 1,617 consecutive patients in the medical ICU.

INTERVENTION

Prospective patient surveillance and data collection.

MEASUREMENTS

Patient demographics, severity of illness, organ system derangements, abdominal processes requiring surgery, and hospital mortality.

RESULTS

Sixty-seven patients in the medical ICU (4.1 percent) developed an acute abdominal process potentially amenable to surgical intervention. Eleven of these patients (16.4 percent) elected not to undergo surgery (mortality = 100 percent). Forty-two of the 56 patients who underwent surgery survived (75.0 percent). Stepwise logistic regression analysis identified two independent objective predictors of mortality for this patient cohort (p < 0.05): an organ system failure index (OSFI) > 2 (adjusted odds ratio [AOR] = 19.5; 95 percent confidence interval [CI], 7.4 to 51.5; p < 0.001); and an APACHE II score > 18 (AOR = 9.4; CI = 3.1 to 28.3; p = 0.03). The observed mortality following surgery was stratified according to the presence or absence of these two factors: neither present, 5.1 percent; APACHE II > 18 present alone, 33 percent; OSFI > 2 present alone, 60 percent; and both present, 88.9 percent (p < 0.001). Surgical nonsurvivors and patients electing not to undergo surgery were similar without significant differences for demographics, severity of illness, or organ system derangements at the time of surgical evaluation.

CONCLUSIONS

The number of organ system derangements and the severity of illness, as assessed by APACHE II, appear to be useful discriminators of outcome for patients in the medical ICU undergoing abdominal surgery. These data suggest potential outcome predictors for this selected group of patients in the ICU.

Abdominal complications following cardiac surgery

Between 1978 and 1991, 116 of 19,246 patients (0.6%) undergoing cardiac surgery developed abdominal complications (renal/hepatic failure excluded) within 30 days of their cardiac operation. Comparison with a randomly selected control group of 217 patients operated upon over the same period of time was also undertaken. Compared to the control group, the study patients were older (mean age, 63.3 +/- 12.5 years vs 57.5 +/- 21.5 years; P = 0.03), more likely to have a history of alcohol abuse (10% vs 4%; P = 0.03), and more likely to have a previous history of gastrointestinal problems (43% vs 17%; P = 0.0001). There was also a trend towards a greater number of patients having valvular surgery, particularly reoperative surgery, in the study group. Postoperatively, patients with marked low cardiac output, requiring the intra-aortic balloon pump, were more likely to develop abdominal complications. These complications included complicated peptic ulcer disease in 54 (47%), intestinal obstruction and/or perforation in 19 (16%), biliary tract disease in 13 (11%), mesenteric ischemia in 13 (11%), acute pancreatitis in 3 (3%), and miscellaneous complications in the remaining 14 (12%). Forty-three patients were treated medically and 73 patients required operative intervention. The surgical procedures performed were truncal vagotomy and drainage (12), oversewing of a perforation or a bleeding vessel (6), gastrectomy (2), intestinal resection (14), laparotomy only (14), cholecystectomy (14), and other (11). Mortality was 26% (30/116) with the mortality for medical and surgical treatment being 16% vs 32%, respectively (P = 0.112). Intestinal ischemia had the highest mortality, with a rate of 85% (11/13). Despite intensive monitoring and care of cardiac surgical patients, abdominal complications do occur, although rarely. Risk factors include older age, a positive history of gastrointestinal disease, reoperative valve surgery, and severe postoperative low cardiac output.

Acute mesenteric ischemia after cardiopulmonary bypass

Three thousand sixty-six patients underwent cardiopulmonary bypass at the Maimonides Medical Center over a 5-year period from January 1, 1987, to January 1, 1992. Of these patients, 1,890 (62%) were less than 70 years of age, 969 (32%) ranged from 70 to 79 years of age, and 207 (7%) were 80 years of age or older. The overall 30-day mortality rate was 8%. Eleven patients developed acute mesenteric ischemia from 24 hours to 12 days postoperatively. At the time of diagnosis, the majority of patients presented with late classical signs and symptoms of acute mesenteric ischemia including abdominal distension, respiratory distress, hypotension, oliguria, and sepsis. All patients underwent immediate laparotomy. Extensive bowel necrosis was found in all, and resection was possible in eight patients. All patients died as a result of this complication. Using the exact trend test, we found a statistically significant increase in the incidence of deaths due to acute mesenteric ischemia after cardiopulmonary bypass in older compared with younger patients. This fatal complication after cardiopulmonary bypass occurs more often than previously believed and is a relatively common cause of death in the elderly.

Diagnostic laparoscopy in the intensive care patient. Avoiding the nontherapeutic laparotomy

Evaluation of a potential acute abdomen in patients who require intensive care for concurrent medical/surgical problems is often difficult due to ambiguities in the physical exam and ancillary diagnostic tests. Between August 1990, and February 1992, 25 ICU patients underwent diagnostic laparoscopy to evaluate a suspected acute intraabdominal process. Thirteen laparoscopies were negative, and 12 were positive. The overall accuracy for laparoscopy was 96% as confirmed by subsequent laparotomy, autopsy, or clinical course. Laparoscopic findings led to a change in management in nine patients (36%), leading to earlier exploration in four patients, and avoidance of laparotomy in five. No significant hemodynamic effects were noted during laparoscopy, and the procedure-related morbidity was low (8.0%). Diagnostic laparoscopy is a safe and accurate guide for managing the ICU patient with a suspected acute surgical abdomen. The use of laparoscopy can help avoid nontherapeutic laparotomy or confirm the need for operative intervention in these complex cases.

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

Interest in the importance of the gut after injury or operation has waxed and waned over this century. Recent studies implicate the gut in septic complications and multiple organ failure after trauma, operations including cardiothoracic procedures, starvation, and other serious illnesses. Changes in the gut in sick patients include stress ulceration, bacterial overgrowth from stress ulceration prophylaxis, mucosal atrophy, loss of barrier function, increased permeability, and bacterial translocation. Such changes in relation to multiorgan failure are reviewed, along with methods to support the gut and prevent gastrointestinal failure. Preventive measures include stress ulceration prophylaxis, selective gut decontamination, enteral feeding, and adjuvants to promote gut function such as glutamine, fiber, and growth hormone. In cardiothoracic operations, the gut may be altered by the "whole body" inflammatory processes of cardiopulmonary bypass. Gastrointestinal complications after cardiothoracic operations are related primarily to low flow states. In 5,924 patients having cardiothoracic operations at St. Louis University Hospital from 1985 to 1991, multiorgan failure developed in 128 patients, with a mortality of 78%. Significant gastrointestinal problems occurred and contributed to multiorgan failure in a number of these patients. Support of the gastrointestinal tract and the prevention of multiorgan failure are important for the cardiothoracic surgeon.

Peripheral organ perfusion augmentation during left ventricular failure. A controlled bovine comparison between the intraaortic balloon pump and the Hemopump

Despite the use of inotropic therapy and the intraaortic balloon pump (IABP), inadequate peripheral organ perfusion and subsequent multiorgan failure from left ventricular dysfunction is a major cause of death following cardiac surgery. To compare the end-organ perfusion provided by the IABP with that of the recently developed Hemopump Cardiac Assist System, blood flow from visceral organs was measured by ultrasonic flow probes during separate periods of support with each of these pumps. Ten calves underwent coronary artery ligations with beta-receptor blockade; hemodynamic parameters were recorded before the induction of failure, during unsupported cardiac failure, and during Hemopump and IABP support. Improvement in mean cardiac output, mixed venous oxygen saturation, and pulmonary artery wedge pressure was significantly greater (p < 0.05) during Hemopump support than during IABP support. Renal artery flow was significantly greater during Hemopump support (276 +/- 74.2 cc/min) than during IABP support (164 +/- 79.6 cc/min). Hepatic artery flow was significantly greater during Hemopump support (34.7 +/- 25.7 cc/min) than during IABP support (24.4 +/- 18.9 cc/min), and portal vein flow was significantly greater during Hemopump support (1588 +/- 315 cc/min) than IABP support (1259 +/- 310 cc/min). There were no significant differences, however, between carotid artery flow during Hemopump support (292 +/- 171 cc/min) and that during IABP support (317 +/- 204 cc/min). We conclude that renal, hepatic, and mesenteric perfusion provided by the nonpulsatile Hemopump is superior to that of the IABP in this bovine model of left ventricular failure. Therefore, the Hemopump may be more effective in preventing multiorgan failure during recovery of ventricular function.

Hyperamylasemia after cardiac surgery. Incidence, significance, and management

The significance of hyperamylasemia and its relationship to pancreatitis after cardiac surgery is controversial. Three hundred consecutive patients undergoing cardiopulmonary bypass were prospectively studied to determine the incidence and significance of postoperative hyperamylasemia. Ninety-six of three hundred patients (32%) developed hyperamylasemia. Fifty-six patients (19%) were classified as having isolated hyperamylasemia because they were asymptomatic and had normal serum lipase. Thirty-two patients (10.7%) had subclinical pancreatitis defined as elevation of serum amylase and lipase or pancreatic isoamylase. Many of these patients had mild gastrointestinal symptoms that were self-limited. Eight patients (2.7%) had overt pancreatitis documented by clinical findings, biochemical abnormalities, and computed tomography (CT) scan or autopsy. Isoamylase analysis demonstrated that isolated hyperamylasemia usually originated from nonpancreatic sources. However, hyperamylasemia occurring in conjunction with abdominal signs and symptoms or elevated serum lipase was almost always pancreatic in origin. Patients with hyperamylasemia had a significantly higher mortality rate (seven of 96 patients, 7.5%) than those with normal serum amylase (two of 204 patients, 0.9%) (p less than 0.01) even when the amylase was nonpancreatic in origin (five of 56 patients, 9%). The reason that nonpancreatic hyperamylasemia is associated with increased postoperative mortality is not established but may represent a variety of metabolic aberrations or tissue injuries. It is concluded that 1) hyperamylasemia after cardiopulmonary bypass is a marker of potential clinical importance, and 2) pancreatitis in this setting is more common than previously recognized and is a potentially lethal complications. Successful treatment depends on early diagnosis and aggressive treatment.