Literature review

Abstract

Gong M, Thompson T, Williams P, et al: Clinical predictors of and mortality in acute respiratory distress syndrome: Potential role of red cell transfusion. Crit Care Med 33:1191-1198, 2005 While allogeneic blood transfusion is life-saving in some patients, it has been associated with morbid outcomes in both medical and surgical patient populations. Aged stored blood, immunomodulatory effects, and changes associated with the systemic inflammatory response syndrome have been hypothesized to mediate the negative effects of transfusion on clinical outcomes. In a prospective, observational study of 688 patients at risk for non-trauma-related acute respiratory distress syndrome (ARDS), Gong and colleagues determined the clinical predictors of ARDS risk and mortality, including the role of packed red blood cell (RBC) transfusion. Patients admitted to the intensive care unit with at least one of a well-defined list of risk factors for ARDS and no exclusion criteria were eligible for the study. Data analysis was with multiple logistic regression. Acute respiratory distress syndrome developed in 32% of patients, with a 60-day mortality rate of 46%. Packed RBC transfusion was an independent risk factor for the development of ARDS (odds ratio [OR], 2.19; 95% confidence interval [CI], 1.42-3.36; p < 0.001). Other significant independent predictors for the development of ARDS included the Acute Physiology and Chronic Health Evaluation (APACHE) III score, age, trauma, diabetes, direct pulmonary injury, hospital transfer, hematocrit greater than 37%, arterial pH less than 7.33, and serum albumin level 2.3 g/dL or less. Packed RBC transfusion was also a significant independent predictor of ARDS mortality (OR, 1.10; 95% CI, 1.04-1.17; p = 0.001). Among those with ARDS, 55% of survivors and 68% of nonsurvivors received transfusions. Survivors received a median of 1 unit of RBCs, compared with 2 units in nonsurvivors. Other significant independent predictors of ARDS mortality included age, APACHE III score, trauma, corticosteroid administration before development of ARDS, and arterial pH less than 7.22. Implication: Packed RBC transfusion is an independent risk factor for ARDS and ARDS-related mortality. This finding is consistent with previous reports linking packed RBC transfusions with adverse clinical outcomes. These data suggest that clinicians should take a more cautious and restrictive approach to transfusion in critically ill patients. Selnes O, Grega M, Borowicz L, et al: Cognitive outcomes three years after coronary artery bypass surgery: A comparison of on-pump coronary artery bypass graft surgery and nonsurgical controls. Ann Thorac Surg 79:1201-1209, 2005 The degree and duration of cognitive decline after coronary artery bypass grafting (CABG) are controversial. It is unclear whether cognitive decline after CABG is related to cardiopulmonary bypass (CPB), age-related changes, or underlying microvascular brain disease. Postoperative changes in cognitive test performance were compared in patients undergoing CABG (n =140) with a demographically similar nonsurgical control group of patients with known risk factors for coronary artery disease (n = 92). All patients completed a baseline neuropsychologic assessment and were followed up at 3, 12, and 36 months. Cognitive performance was assessed with a battery of neuropsychologic tests that measured 8 cognitive domains. Statistical analyses were performed using data from all tested individuals and using a model imputing missing observations for individuals lost to follow-up. Of the 140 patients who underwent CABG, 70 completed the 36-month follow-up testing, 47 refused further testing, 10 died, and 13 were lost to follow-up. Among the 92 nonsurgical control patients, 57 completed the 36-month follow-up testing, 15 refused further testing, 7 died, and 13 were lost to follow-up. The rate of interim medical events in both groups did not significantly differ. The neuropsychologic performance of the patients in the CABG group did not significantly differ from that of the nonsurgical control group at 1 and 3 years. Neuropsychological performance in both the CABG and nonsurgical control groups improved from baseline to 1 year, with both groups demonstrating additional improvements from baseline to 3 years in some cognitive domains. Furthermore, the CABG group exhibited statistically greater improvement than did the nonsurgical control patients in some cognitive subsets. Implication: The neuropsychological performance of patients undergoing CABG does not significantly differ from that of a demographically comparable group of nonsurgical control patients with coronary artery disease at 1 and 3 years. These data suggest that previous reports of late cognitive decline after CABG may be unrelated to the use of CPB, but may also occur in patients with similar risk factors for cardiovascular and cerebrovascular disease. Jin R, Grunkemeier G, Furnary A, et al: Is obesity a risk factor for mortality in coronary artery bypass surgery? Circulation 111:3359-3365, 2005 Since 1991, the prevalence of obesity in adults in the United States has increased by more than 75%. Today, approximately 65% of all persons 20 years of age or older are overweight or obese. To investigate the effect of obesity on postoperative outcomes, a retrospective study was conducted in 16,218 patients enrolled in the Providence Health System Cardiovascular Study Group database who underwent isolated coronary artery bypass grafting (CABG) from 1997 to 2003. Body mass index (BMI) was defined as follows: underweight, less than 18.5 kg/m2; normal, 18.5 to 24.9 kg/m2; overweight, 25 to 29.9 kg/m2; and obese, greater than 30 kg/m2. Obesity was further subdivided into the following subgroups: mild, 30 to 34.9 kg/m2; moderate, 35 to 39.9 kg/m2; and extreme, 40 kg/m2. Measured clinical outcomes included in-hospital mortality, stroke, myocardial infarction, deep sternal wound infection, renal failure, need for blood transfusion, length of stay, need for mechanical ventilation, reoperation for cardiac reason, and postoperative coronary angiography intervention. Data analysis was with multivariate logistic regression. Body mass index was not a significant risk factor for postoperative in-hospital mortality, including in women, who had higher BMIs than did men in the same age group. Using cumulative sum techniques, the lowest risk-adjusted postoperative in-hospital mortality was found to be in the high-normal and overweight BMI subgroups, with underweight and obese patients having slightly increased mortality. Body mass index was independently associated with increased risk for deep sternal infection and renal failure, and decreased risk for postoperative blood transfusion, coronary angiography intervention, and reoperation. Implication: Although obesity is a well-known risk factor for coronary artery disease and hypertension, these data suggest that body size is not a significant risk factor for in-hospital mortality after CABG. However, obesity may be associated with increased risk for postoperative sternal infection and renal failure. Lo B, Fijnheer R, Nierich A, et al: C-reactive protein is risk indicator for atrial fibrillation after myocardial revascularization. Ann Thorac Surg 79:1530-1535, 2005 Atrial fibrillation (AF) occurs in as many as one third of patients undergoing cardiac surgery and is associated with significant increases in hospital resource use. Although multiple demographic and perioperative factors have been associated with the development of postoperative AF, the mechanism by which cardiac surgery predisposes patients to AF is unknown. Recent evidence suggests that postoperative AF may be associated with postoperative inflammation. To investigate whether baseline levels of the inflammatory marker C-reactive protein (CRP) were associated with postoperative AF, Lo and colleagues examined the last 152 consecutive patients enrolled in the randomized OCTOPUS study, which compared patients undergoing coronary artery bypass grafting (CABG) with (n = 73) or without (n = 79) the use of cardiopulmonary bypass. Patients requiring emergency surgery, with poor left ventricular function, or scheduled to undergo major concomitant surgery were excluded from the study. Data analysis was with multivariate logistic regression. Baseline CRP levels did not significantly differ between groups. Thirty-four patients had postoperative AF; 22 patients were in the on-pump group and 12 were in the off-pump group. To determine whether preoperative CRP levels were associated with postoperative AF, both groups were subdivided into low (<3.0 mg/L) and high (≥3.0 mg/L) baseline CRP levels. In the off-pump group, AF occurred in 4 (8%) of 52 patients with low baseline CRP levels v 8 (30%) of 27 patients with high preoperative CRP levels (p = 0.002). When both the on-pump and off-pump groups were combined, AF occurred in 15 (14%) of 105 patients in the low baseline CRP group and 19 (40%) of 47 patients in the high baseline group (odds ratio [OR], 4.1; 95% confidence interval [CI], 1.8-9.1). The adjusted OR was 3.3 (95% CI, 1.4-7.6) for development of postoperative AF as a function of high baseline CRP in both groups together. Baseline CRP levels (p = 0.02), age, and type of surgery were also significant independent predictors of postoperative AF. Hypertension, peripheral vascular disease, β-blocker use, hypercholesterolemia, chronic obstructive pulmonary disease, and chronic renal failure were not independently associated with increased risk for postoperative AF. Implication: Patients with high baseline CRP levels are at increased risk for development of postoperative AF after both on-pump and off-pump cardiac surgery. Although baseline CRP levels may be useful for postoperative AF risk stratification, a randomized controlled trial is still needed to determine whether prophylactic pharmacologic intervention would be beneficial in patients with elevated baseline CRP levels. Serruys P, Ong A, van Herwerden L, et al: Five-year outcomes after coronary stenting versus bypass surgery for the treatment of multivessel disease: The final analysis of the Arterial Revascularization Therapies Study (ARTS) randomized trial. J Am Coll Cardiol 46:575-581, 2005 It is unclear at present whether stenting or coronary artery bypass grafting (CABG) is preferable for the long-term treatment of multivessel coronary artery disease. The Arterial Revascularization Therapies Study (ARTS) was a randomized, controlled, multicenter trial designed to compare CABG v stenting in patients with multivessel coronary disease. A total of 1205 patients with the potential for equivalent revascularization were randomly assigned to CABG (n = 605) or stent implantation (n = 600). The primary end point of the study was freedom from major adverse cardiac and cerebrovascular events at 1 year, with the secondary endpoints being freedom from major adverse cardiac and cerebrovascular events at 3 and 5 years. Event-free survival was assessed with the Kaplan-Meier method, and differences were assessed with the long-rank test. Complete follow-up was available at 5 years in 98.3% of patients in the stent group and 96.6% of patients in the CABG group. At 5 years, there were 48 deaths in the stent group and 46 deaths in the CABG group (8.0% v 7.6%; p = 0.83; relative risk [RR], 1.05; 95% confidence interval [CI], 0.71-1.55). Overall freedom from death, stroke, or myocardial infarction was not significantly different between groups (18.2% in the stent group v 14.9% in the CABG group; p = 0.14; RR, 1.22; 95% CI, 0.95-1.58). However, the incidence of repeat revascularization was significantly higher in the stent group (30.3%) than in the CABG group (8.8%; p < 0.001; RR, 3.46; 95% CI, 2.61-4.60). Further, at the end of 5 years, 10.5% of patients originally assigned to the stent group required CABG and 23.3% underwent a second percutaneous coronary intervention (PCI). Conversely, 1.2% of patients originally assigned to the CABG group required reoperation and 8.3% required revascularization with PCI. The 5 year composite event-free survival rate was 58.3% in the stent group and 78.2% in the CABG group (p < 0.0001; RR, 1.91; 95% CI, 1.60-2.28). In addition, there was a significant difference between groups in the presence of anginal symptoms at 5 years (21.2% in the stent group v 15.5% in the CABG group; p < 0.05). Significantly more patients in the stent group were receiving nitrates, β-blockers, or calcium channel antagonists. Analysis of a subgroup of patients with diabetes (n = 208) revealed that mortality was 13.4% in the stent group v 8.3% in the CABG group (p = 0.27; RR, 1.61; 95% CI, 0.71-3.63). Implication: There is no significant difference in mortality, stroke, or myocardial infarction in patients receiving stents or undergoing CABG to treat multivessel coronary disease at 5 years. However, the overall incidence of major adverse cardiac and cerebrovascular events at 5 years is higher in patients receiving stents, largely because of the need for repeat revascularization. Inasmuch as this study did not include drug-eluting stents, further long-term follow-up data are needed to assess the effect of stents on the need for repeat revascularization. Barrera R, Shi W, Amar D, et al: Smoking and timing of cessation: Impact on pulmonary complications after thoracotomy. Chest 127:1977-1983, 2005 Cigarette smoking is associated with increased postoperative pulmonary complications after thoracic surgery. However, many of the benefits of discontinuing smoking are not immediate, including reduced mucous secretion, and improvement in mucociliary transport and small airways function. Furthermore, there have been reports of paradoxic increases in the rate of pulmonary complications in smokers who have recently quit, possibly related to increased intraoperative sputum production. Thus it is unclear whether patients who have been abstinent for less than 2 months have a higher rate of postoperative complications compared with nonsmokers, current smokers, or those who quit in the distant past. Barrera and colleagues examined the effect of smoking history and timing of smoking cessation on postoperative pulmonary complications in 300 consecutive patients undergoing thoracotomy for resection of primary or secondary lung tumors. The study groups included nonsmokers (21%), previous smokers who quit longer than (62%) or less than (13%) 2 months earlier, and ongoing smokers (4%). Measured end points included postoperative pulmonary complications, defined as respiratory failure requiring admission to the intensive care unit, or intubation, pneumonia, atelectasis requiring bronchoscopy, pulmonary embolism, or the need for supplemental oxygen at hospital discharge. Data analysis was with multivariate logistic regression. Fifty-one (17%) of 300 patients had postoperative pulmonary complications. Length of stay was significantly longer in patients with pulmonary complications compared with those without pulmonary complications (median, 8 v 6 days; p < 0.0001). The distribution of pulmonary complications was 8% in nonsmokers, 19% in smokers who quit more than 2 months earlier, 23% in smokers who quit within 2 months, and 23% for current smokers. Nonsmokers had lower pulmonary complication rates compared with all smokers (p = 0.03), with no difference detected among subgroups of smokers (p = 0.76). Significant independent predictors of postoperative pulmonary complications included a lower than predicted diffusing capacity of the lung for carbon dioxide [odds ratio [OR] per 10% decrement, 1.41; 95% confidence interval [CI], 1.17-1.70; p = 0.01] and a diagnosis of primary lung cancer (OR, 3.94; 95% CI, 1.34-11.59; p = 0.003). Comparing recent quitters and ongoing smokers, no differences in pulmonary complications or pneumonia were found (p = 0.67). Implication: Smokers experience more postoperative pulmonary complications than do nonsmokers after lung surgery. Although there was no evidence of a paradoxic increase in pulmonary complications in patients who quit smoking within 2 months of surgery, and that it is extremely likely that smoking cessation can safely be encouraged before surgery, it should be noted that the present study was not sufficiently powered to detect significant differences between nonsmokers and each individual smoker subgroup; that is, it was powered only to detect significant differences between nonsmokers and all smokers. Roselli E, Murthy S, Rice T, et al: Atrial fibrillation complicating lung cancer resection. J Thorac Cardiovas Surg 130:438-444, 2005 Atrial fibrillation (AF) is a common complication that occurs in approximately 20% of patients undergoing thoracotomy for lung resection. The present study investigated whether postoperative AF is associated with increased risk for postoperative complications in thoracic surgical patients. Subjects consisted of 604 consecutive patients undergoing anatomic resection because of non–small cell cancer at a tertiary referral center. Atrial fibrillation prevalence, onset, and temporal association with other postoperative complications were determined. No attempt was made to prevent postoperative AF. All patients had cardiac telemetry throughout their hospital stay, with postoperative AF being defined electrocardiographically. Measured postoperative complications were categorized as cardiovascular, respiratory, infectious, or renal. Atrial fibrillation economics were also assessed, using 91 propensity-matched pairs. Atrial fibrillation occurred in 113 (19%) patients, with peak onset on postoperative day 2. Patients free of AF by postoperative day 5 seldom developed it. Risk factors for postoperative AF included increased age, male sex, history of paroxysmal AF, heart failure, clamshell incision, and right-sided pneumonectomy (p < 0.01). Among the 113 patients who had postoperative AF, it was a solitary complication in 75 patients, with additional postoperative complications occurring in 38 patients. In the 91 propensity-matched pairs, patients with AF had more postoperative complications (30% v 9%; p < 0.0004), had longer postoperative stays (median, 8 v 5 days; p < 0.0001), incurred higher costs (cost ratio, 1.8; 68% CI, 1.6-2.1), and had a higher rate of in-hospital mortality (8% v 0%; p = 0.01). Even when AF was a solitary postoperative complication, hospital stay (median, 7 v 5 days; p < 0.0001) and cost were increased (cost ratio, 1.5; 68% CI, 1.2-1.6). Implication: Atrial fibrillation is a frequent complication in patients undergoing pulmonary resection and is related to both patient and procedural variables. Because postoperative AF is associated with increased hospital stay and costs, it should be promptly treated and should increase clinical suspicion for other potential postoperative complications. Halm E, Hannan E, Rojas M, et al: Clinical and operative predictors of outcomes of carotid endarterectomy. J Vasc Surg 42:420-428, 2005 Predictors of poor outcome after carotid endarterectomy (CEA) continue to be defined. In a retrospective, multicenter investigation of 1972 patients undergoing CEA, Halm and colleagues sought to identify perioperative risk factors associated with death or nonfatal stroke within 30 days of surgery. Multivariate logistic regression was used to identify independent clinical characteristics and operative techniques associated with risk-adjusted rates of combined death and nonfatal stroke, and all strokes. Death or stroke occurred in 2.28% of patients without carotid symptoms, 2.93% of those with carotid transient ischemic attacks, and 7.11% of those with stroke (p < 0.0001). Three clinical factors that increased the risk-adjusted odds of complications were stroke as the indication for surgery (odds ratio [OR], 2.84; 95% confidence interval [CI], 1.55-5.20), presence of active coronary artery disease (OR, 3.58; 95% CI, 1.53-8.36), and contralateral carotid stenosis greater than 50% (OR, 2.32; 95% CI, 1.33-4.02). Two surgical techniques that reduced the risk-adjusted odds of death or stroke were use of local anesthesia (OR, 0.30; 95% CI, 0.16-0.58), and patch closure (OR, 0.43; 95% CI, 0.24-0.76). Implication: The risk for postoperative death or stroke after CEA is significantly increased in patients who have had a previous stroke, have active coronary artery disease, or have significant contralateral carotid stenosis. Further, these data support the need for a randomized clinical trial comparing general and local anesthesia, because local anesthesia may reduce the risk for postoperative death and stroke after CEA. Articles reviewed in this issue were selected from those published in the following journals: Critical Care Medicine, Annals of Thoracic Surgery, Circulation, Journal of the American College of Cardiology, Chest, Journal of Thoracic and Cardiovascular Surgery, and Journal of Vascular Surgery.