Magnitude of the inflammatory response to cardiopulmonary bypass and its relation to adverse clinical outcomes.

INTRODUCTION: Cardiopulmonary bypass (CPB) induces an inflammatory response believed to contribute to postoperative morbidity. We hypothesized that the magnitude of the inflammatory response following CPB would be associated with adverse clinical outcomes. METHODS: Twenty-nine patients had plasma TNF, IL-6, IL-8, elastase, histamine, complement C5a, and complement C3a measured by ELISA before, during, and after cardiac operations employing CPB. Inflammatory mediator levels were analyzed with respect to outcomes. RESULTS: Mediator levels peaked at 4 h post-CPB and either returned to baseline or substantially decreased by 24 h. Patients with peak mediator levels above the median for the group as a whole were classified as 'hyper-responders'; those with levels below the median were classified as 'normal responders'. While IL-8, C3a, and IL-6 levels were independently associated with adverse outcomes, TNF, histamine, and C5a levels were not. Elastase levels trended towards adverse outcomes. IL-8 'hyper-responders' experienced significantly greater postoperative weight gain and had higher IL-8 levels at 24 h (p<0.05), with trends towards renal impairment and protracted supplemental oxygen requirements. C3a 'hyper-responders' strongly trended towards increased bleeding, delayed extubation, greater postoperative weight gain, and decreased levels of independent functioning at discharge (p < or = 0.10). IL-6 'hyper-responders' experienced significantly more postoperative bleeding, delayed extubation, and higher IL-6 levels at 24 h compared to 'normal responders' (p < 0.05). They strongly trended towards greater postoperative weight gain and decreased levels of independent functioning at discharge (p < or = 0.10). CONCLUSIONS: Patients who have an exaggerated inflammatory response to CPB tend to bleed more, require more respiratory support, demonstrate greater capillary leak via weight gain, and display a decline in independent functioning relative to normal responders. Thus, it appears that the magnitude of the inflammatory response to CPB adversely influences clinical outcomes.

Elevated intestinal fatty acid binding protein and gastrointestinal complications following cardiopulmonary bypass: a preliminary analysis.

BACKGROUND: Cardiopulmonary bypass (CPB) is associated with poorly understood alterations in gastrointestinal (GI) perfusion. Intestinal fatty acid binding protein (IFABP), a cytosolic protein uniquely located in mature small-intestinal enterocytes, has been shown to be a sensitive biochemical marker of early intestinal ischemia when assayed in urine. We hypothesized that if significant small-intestinal ischemia occurs with CPB, then urine IFABP levels should be concomitantly elevated. METHODS: Twenty-nine patients (15 low risk and 14 high risk) undergoing cardiac surgery with CPB were studied prospectively. Serial urine IFABP levels were measured and results were correlated with clinical outcomes. RESULTS: None of the low-risk patients had IFABP elevations or experienced GI complications. Five of the high-risk patients had IFABP elevations, and three of the five developed GI complications. Within the high-risk cohort, the only significant difference between patients with or without IFABP elevations was the GI complication rate (P = 0.03). Overall, patients with IFABP elevations had a significantly higher mean ASA class and significant increases in mean CPB and aortic cross-clamp times, mean time to oral intake, median ICU and postoperative lengths of stay, and GI complications. CONCLUSIONS: In low-risk bypass patients, small-bowel mucosal perfusion appeared to be maintained, while in the high-risk population, 21% of the patients sustained clinically significant mucosal compromise. In this pilot study, urine IFABP was 100% sensitive and 92% specific with respect to GI complications. Since elevated urine IFABP concentrations appeared to correlate with clinical GI complications, urine IFABP may be a useful marker to identify the patient at risk for postbypass GI complications.

Beta blockade to prevent atrial dysrhythmias following coronary bypass surgery.

BACKGROUND: Atrial fibrillation and atrial flutter (AF) frequently complicate coronary artery bypass surgery (CABG) and increase hospital stay as well as morbidity. Studies of drug prophylaxis to prevent AF with beta-adrenergic blocking agents administered in fixed doses have had conflicting results. METHODS: One hundred patients were randomized to receive metoprolol or placebo following CABG. A dosing algorithm was used to achieve clinically significant beta-adrenergic blockade. RESULTS: There was no significant difference between the incidence of AF in the metoprolol (24%) and placebo (26%) groups. However, the incidence of AF in all patients having CABG at this institution declined over the period of the study from 31% to 23% (P < .025), in association with the adoption of a continuous technique of cardioplegia delivery. CONCLUSIONS: Metoprolol is not efficacious for the prevention of post-CABG AF even when dosage is titrated to achieve clinical evidence of beta blockade. It is likely that the adoption of a continuous cardioplegia technique caused a reduction in our incidence of post-CABG AF.

Selection of patients for same-day coronary bypass operations.

Between March 15, 1990, and December 31, 1991, we admitted to the Virginia Mason Hospital for isolated coronary bypass operations 175 consecutive patients with chronic, stable angina pectoris who had prior coronary arteriography. One hundred patients were admitted on the same day as their operations, and 75 patients, deemed to be at higher risk, were admitted 1 day before the operation. Postoperative progress of all patients was monitored by means of a clinical pathway form with physiologic and activity measures plotted against postoperative days. We found no difference in age, sex, or total number of comorbidity factors. Diabetes and ejection fraction less than 0.50 were significantly more common in preoperatively admitted patients and were independently predictive of admitting group. Significant differences between surgeons in the proportion of same-day patients admitted could not be explained by differences in common risk factors. There was no significant difference in postoperative major or minor complications or number of clinical pathway deviations, but two deaths occurred in patients admitted preoperatively. Average total hospital stay was 1 1/2 days less for same-day patients, a highly significant difference. Total hospital charges averaged $19,000 for the series and were $286 more for preoperatively admitted patients, a difference that was not statistically significant. Patients admitted selectively for same-day coronary bypass are not at risk for an increased number of complications. Although their hospital stay is reduced, the reduction of their hospital charges is minimal. Preoperative admission of patients with comorbidity requiring medical management or with physical incapacity remains justified, and admitting decisions should remain with the operating surgeon, not third parties.

Mitral valve reconstruction.

Modern repair techniques allow reconstruction rather than replacement of the mitral valve (MV) in the majority of patients requiring operation. Such patients are now older and more likely to have nonrheumatic MV disease than those treated in former years. A continuing experience with MV reconstruction was reviewed to determine its safety and efficacy. In 50 patients undergoing isolated MV reconstructions, there have been no postoperative deaths. In 36 patients undergoing mitral reconstruction combined with other cardiac procedures, there have been 5 deaths (14%). Three patients have required MV replacement for an inadequate repair as determined by evaluation during the repair or by intraoperative transesophageal echocardiography (TEE) following cardiopulmonary bypass. Overall complications have included five reoperations for bleeding, two perioperative myocardial infarctions, two strokes, and one aortic dissection. The majority of patients maintain an improved functional state after operation. Multiple reconstructive maneuvers are now available, and the elements of any given reconstruction depend on the pathoanatomy of the valve. Intraoperative TEE has been invaluable in planning, evaluating, and modifying repairs. At present, over 70% of all MV operations are reconstructions, and the most common recent indication for MV replacement is a malfunctioning prosthetic MV rather than native valve disease.

Continuing experience with the automatic implantable cardioverter defibrillator.

The automatic implantable cardioverter defibrillator (AICD) is now used commonly in the management of malignant ventricular arrhythmias. Its use may obviate the need for antiarrhythmic drugs or endocardial resection. We reviewed our continuing experience with the AICD to determine its safety and efficacy. Since June 1987, 102 patients (mean age: 63 years) who survived out-of-hospital ventricular fibrillation or hemodynamically unstable ventricular tachycardia not associated with acute myocardial infarction underwent implantation of an AICD. There were three operative deaths and nine complications. Eighty-nine patients are alive. No patient has experienced sudden cardiac death. Forty-two patients (43%) have had 1 or more AICD discharges associated with symptoms of cardiac arrest. During AICD implantation, it appears preferable to configure lead placement by individual patient characteristics rather than by a rigid protocol. The relative safety and efficacy of the AICD support its use as an alternative to toxic medications or more dangerous endocardial resection in suboptimal candidates.

Evaluation of the patient having cardiac surgery in the postoperative rewarming period.

Ensuring adequate oxygen delivery to the tissues with respect to oxygen demand is the treatment goal in patients undergoing coronary artery surgery (CAS). In this study we examined changes in temperature, arterial oxygen saturation (SaO2), cardiac index (CI), oxygen consumption (VO2), and mixed venous oxygen saturation (SvO2) over the initial 4-hour rewarming period in 36 patients having CAS. When patients were admitted to the intensive care unit the mean temperature was 36.27 degrees C, and it increased to 37.50 degrees C; SaO2 was 97.67% at the beginning and end of the 4-hour period; CI was 2.88 L/min/m2 and rose to 3.00 L/min/m2; VO2 was high at 0.320 L/min on admission and remained high at 0.290 L/min at the end of the 4-hour rewarming period; and SvO2 was 70.83% initially and declined to 66.53% in the same period of time. Continuous SvO2 monitoring was valuable in the ongoing assessment and management of the patients in stable, mildly hypothermic condition after CAS during the 4-hour postoperative rewarming period.

Effects of position changes on mixed venous oxygen saturation in patients after coronary revascularization.

The purpose of this study was to investigate the effects of position changes on mixed venous oxygen saturation (SvO2) and to describe the mechanisms responsible for SvO2 changes reported to occur with position changes. The study was done from 4 to 8 hours after surgery in 34 patients after coronary artery bypass grafting. Subjects were put through a series of six position changes, including head of bed elevations and right and left lateral decubitus with return to supine between each. Each position was maintained for 30 minutes. SvO2, arterial oxygen saturation (SaO2), and oxygen consumption (VO2) were measured before and after each position change. Overall mean subject data demonstrated a decrease in SvO2 with each of the lateral position changes. The SvO2 did not drop below 60% in these mean data, and this drop returned to baseline by 5 minutes. There were no significant changes in the mean data for VO2 or SaO2. No significant correlation was found in the mean data between SvO2 and VO2 or SvO2 and SaO2 measurements. Trends were demonstrated in five specific cases that suggested a correlation between changes in SvO2 and changes in VO2 and SaO2. In conclusion, this study demonstrated that subjects were able to tolerate position changes with no clinically significant changes in SvO2, SaO2, or VO2.

Early experience with the automatic implantable cardioverter defibrillator in sudden death survivors.

Medical management of life-threatening ventricular arrhythmias is difficult because of the toxicity and limited efficacy of antiarrhythmic drugs. The automatic implantable cardioverter defibrillator (AICD) offers protection against malignant ventricular arrhythmias and allows some patients to be managed without antiarrhythmic drugs. We reviewed our experience with the AICD to determine its safety and efficacy. Since June 1987, 24 patients (mean age 63 years) who survived out-of-hospital ventricular fibrillation or hemodynamically unstable ventricular tachycardia not associated with acute myocardial infarction had implantation of an AICD. None had inducible monomorphic ventricular tachycardia associated with ventricular aneurysm. Twenty-three had abnormal left ventricular function (mean ejection fraction 0.32). There were no operative deaths and three complications. At last follow-up (mean 8.9 months) 23 patients were alive. Eight patients had one or more AICD discharges associated with symptomatic or monitored cardiac arrest. AICD implantation can be performed with low risk and appears to be an effective alternative to antiarrhythmic therapy with toxic drugs.

Introducer insertion of mini-thoracostomy tubes.

Introducer insertion of a small caliber chest tube is easily mastered, fast, and nearly painless. Outpatient management of spontaneous pneumothorax with a 12 F. polyvinylchloride catheter and a Heimlich valve appears both safe and economical in a selected group of patients. Introducer chest tube insertion is well tolerated, in contrast to the discomfort experienced during insertion of chest tubes by means of blunt dissection or trocar. In addition, the high risk of injury to the lung or other viscera by trocars is avoided.

Appendiceal abscess.

Of 61 patients with appendiceal abscess, 32 were treated by incision and drainage without appendectomy, with 16% morbidity. Seventeen patients had incision and drainage with appendectomy, with 24% morbidity. One patient, admitted in septic shock, died without operation. Average hospitalization was shortest in the nine patients treated nonoperatively. Many patients with appendiceal mass or abscess do not require immediate operation. In the 42 patients discharged without appendectomy, the recurrence rate of appendicitis was 5% at 9.1 months' average follow-up. Thirty-two elective interval appendectomies were performed at an average interval of 96 days, with 13% morbidity. At interval appendectomy, those patients from whom a free fecalith had been removed at the time of drainage had the greatest degree of appendiceal destruction. Interval appendectomy is probably not necessary in such patients.