John E. Scarborough

Effects of ischemia on pulmonary dysfunction after cardiopulmonary bypass

BACKGROUND Pulmonary hypertension and lung injury secondary to cardiopulmonary bypass (CPB) are probably caused by a combination of ischemia and inflammation. This study was undertaken to investigate the potential ischemic effects of cessation of pulmonary arterial flow during CPB on pulmonary injury. METHODS Twenty neonatal piglets (2.5 to 3.1 kg) were randomly assigned to two groups. Group A (n = 10) underwent 90 minutes of CPB at full flow (100 mL x kg(-1) x min(-1)) and clamping of the main pulmonary artery (PA). Group B (n = 10) underwent 90 minutes of partial CPB (66 mL x kg(-1) x min(-1)) with continued mechanical ventilation and without clamping of the PA. All hearts were instrumented with micromanometers and a PA ultrasonic flow probe. Endothelial function was assessed by measuring endothelial-dependent relaxation (measured by change in pulmonary vascular resistance after PA infusion of acetylcholine) and endothelial-independent relaxation (measured by change in pulmonary vascular resistance after ventilator infusion of nitric oxide and PA infusion of sodium nitroprusside). RESULTS All groups exhibited signs of pulmonary injury after CPB as evidenced by significantly increased pulmonary vascular resistance, increased alveolar-arterial O2 gradients, and decreased pulmonary compliance (p<0.05); however, pulmonary injury was significantly worse in group A (p<0.05). CONCLUSIONS This study suggests that although exposure to CPB alone is enough to cause pulmonary injury, cessation of PA flow during CPB contributes significantly to this pulmonary dysfunction.

Low volume is associated with worse patient outcomes for pediatric liver transplant centers.

BACKGROUND An inverse association between hospital procedure volume and postoperative mortality has been demonstrated for a variety of pediatric surgical procedures. The objective of our study was to determine whether such an association exists for pediatric liver transplantation. METHODS We performed a retrospective analysis of pediatric liver transplant procedures included in the Scientific Registry of Transplant Recipients over a 7.5-year time period from July 1, 2000, through December 31, 2007. Pediatric liver transplant centers were divided into three volume categories (high, middle, low) based on absolute annual volume. Mean 1-year patient survival rates and aggregate 1-year observed-to-expected (O:E) patient death ratios were calculated for each hospital volume category and then compared using ordered logistic regression and chi square analyses. RESULTS High-volume pediatric liver transplant centers achieved significantly lower aggregate 1-year O:E patient death ratios than low-volume centers. When freestanding childrens hospitals (FCH), childrens hospitals within adult hospitals (CAH), and other centers (OC) were considered separately, we found that a significant volume-outcomes association existed among OC centers but not among FCH or CAH centers. Low-volume OC centers, which represent 41.6% of all pediatric liver transplant centers and perform 10% of all pediatric liver transplantation, had the least favorable aggregate 1-year O:E patient death ratio of all groups. CONCLUSIONS We demonstrate that a significant center volume-outcomes relationship exists among OC pediatric liver transplant centers but not among FCH or CAH centers. These findings support the possible institution of minimum annual procedure volume requirements for OC pediatric liver transplant centers.

Regional versus general anesthesia for carotid endarterectomy: The American College of Surgeons National Surgical Quality Improvement Program perspective

BACKGROUND The ideal anesthetic technique for carotid endarterectomy remains a matter of debate. This study used the American College of Surgeons National Surgical Quality Improvement Program to evaluate the influence of anesthesia modality on outcomes after carotid endarterectomy. METHODS Postoperative outcomes were compared for American College of Surgeons National Surgical Quality Improvement Program patients undergoing carotid endarterectomy between 2005 and 2009 with either general or regional anesthesia. A separate analysis was performed on a subset of patients matched on propensity for undergoing carotid endarterectomy with regional anesthesia. RESULTS For the entire sample of 24,716 National Surgical Quality Improvement Program patients undergoing carotid endarterectomy and the propensity-matched cohort of 8,050 patients, there was no difference in the 30-day postoperative composite stroke/myocardial infarction/death rate based on anesthetic type. Within the matched cohort, the rate of other complications did not differ (2.8% regional vs. 3.6% general anesthesia; P = .07), but patients receiving regional anesthesia had shorter operative (99 ± 36 minutes vs 119 ± 53 minutes; P < .0001) and anesthesia times (52 ± 29 minutes vs. 64 ± 37 minutes; P < .0001) and were more likely to be discharged the next day (77.0% vs 64.4%; P < .0001). CONCLUSION Anesthesia technique does not impact patient outcomes after carotid endarterectomy, but may influence overall cost of care.

Modified Ultrafiltration Versus Conventional Ultrafiltration: A Randomized Prospective Study In Neonatal Piglets☆☆☆★★★

UNLABELLED Cardiopulmonary bypass in neonates generates large increases in inflammatory mediators, causing edema formation that may lead to multiple organ dysfunction. Clinical strategies aimed at removing inflammatory mediators, reducing edema formation, and improving organ function include conventional and modified ultrafiltration. OBJECTIVE This study examines the effectiveness of conventional and modified ultrafiltration in preventing weight gain, myocardial edema formation, and left ventricular dysfunction in neonatal piglets undergoing cardiopulmonary bypass. METHODS In this randomized prospective study, 18 1-week-old piglets were supported with cardiopulmonary bypass at 100 ml kg(-1) x min(-1), cooled to 25 degrees C, exposed to 75 minutes of cardioplegic arrest, rewarmed to 37 degrees C, and weaned from bypass. Left ventricular myocardial contractility was assessed by the preload-recruitable stroke work method, with the use of a sonomicrometric two-dimensional cylindrical model, before bypass and at 10, 60, and 120 minutes after separation from bypass. RESULTS Total body weight gain was significantly less in the modified ultrafiltration group than in either the conventional ultrafiltration group or the control group (no filtration). Myocardial wet/dry ratios were also improved with modified ultrafiltration, but not with conventional ultrafiltration, when compared with no filtration (control group). Hemodynamically, modified ultrafiltration was superior to conventional ultrafiltration and no filtration (control) in raising the mean arterial pressure and increasing the left ventricular preload-recruitable stroke work after bypass. CONCLUSION Modified ultrafiltration is superior to conventional ultrafiltration and no filtration in reducing the total body weight gain, lessening myocardial edema, raising mean arterial pressure, and improving left ventricular contractility in neonatal piglets undergoing cardiopulmonary bypass and cardioplegic arrest.

Concomitant Vascular Reconstruction During Pancreatectomy for Malignant Disease: A Propensity Score–Adjusted, Population-Based Trend Analysis Involving 10 206 Patients

OBJECTIVE To assess trends in the frequency of concomitant vascular reconstructions (VRs) from 2000 through 2009 among patients who underwent pancreatectomy, as well as to compare the short-term outcomes between patients who underwent pancreatic resection with and without VR. DESIGN Single-center series have been conducted to evaluate the short-term and long-term outcomes of VR during pancreatic resection. However, its effectiveness from a population-based perspective is still unknown. Unadjusted, multivariable, and propensity score-adjusted generalized linear models were performed. SETTING Nationwide Inpatient Sample from 2000 through 2009. PATIENTS A total of 10,206 patients were involved. MAIN OUTCOME MEASURES Incidence of VR during pancreatic resection, perioperative in-hospital complications, and length of hospital stay. RESULTS Overall, 10,206 patients were included in this analysis. Of these, 412 patients (4.0%) underwent VR, with the rate increasing from 0.7% in 2000 to 6.0% in 2009 (P < .001). Patients who underwent pancreatic resection with VR were at a higher risk for intraoperative (propensity score-adjusted odds ratio, 1.94; P = .001) and postoperative (propensity score-adjusted odds ratio, 1.36; P = .008) complications, while the mortality and median length of hospital stay were similar to those of patients without VR. Among the 25% of hospitals with the highest surgical volume, patients who underwent pancreatic surgery with VR had significantly higher rates of postoperative complications and mortality than patients without VR. CONCLUSIONS The frequency of VR during pancreatic surgery is increasing in the United States. In contrast with most single-center analyses, this population-based study demonstrated that patients who underwent VR during pancreatic surgery had higher rates of adverse postoperative outcomes than their counterparts who underwent pancreatic resection only. Prospective studies incorporating long-term outcomes are warranted to further define which patients benefit from VR.

Neurologic outcomes after coronary artery bypass grafting with and without cardiopulmonary bypass

Neurologic injury, in the form of either stroke or more subtle neurocognitive impairment, is a frequent and potentially devastating complication of coronary artery bypass grafting (CABG). The etiology of CABG-associated neurologic injury is likely multifactorial, with the phenomena of cerebral hypoperfusion and embolism being the major contributors. Several perioperative strategies have been developed in an effort to reduce the incidence of CABG-associated neurologic complications. Hypothermic cerebral perfusion, alpha stat acid-base management, and slow patient rewarming have been shown by several investigators to minimize adverse neurologic sequelae associated with the use of cardiopulmonary bypass. Performing CABG without cardiopulmonary bypass (off-pump CABG), meanwhile, has been shown to reduce the risk of perioperative stroke, especially in high-risk patients such as the elderly. Whether off-pump CABG reduces the incidence of less severe neurocognitive impairment has not yet been clearly established and merits further investigation in the form of large, multicenter, randomized trials. Other technical innovations, such as the use of sutureless and clampless aortic anastomotic devices, also may be able to further minimize the neurologic complications associated with CABG.

Advanced age is an independent predictor for increased morbidity and mortality after emergent surgery for diverticulitis

BACKGROUND The objectives of our study were to determine the association between age and postoperative outcomes after emergency surgery for diverticulitis and to identify risk factors for postoperative mortality among elderly patients. METHODS All patients from the American College of Surgeons National Surgical Quality Improvement Program 2005-2009 Participant User Files undergoing emergent surgery for diverticulitis were included. Multivariate logistic regression was used to determine the association between age and postoperative morbidity and mortality after adjustment for perioperative variables. A separate regression model was used to determine risk factors for postoperative mortality among elderly patients, with specific postoperative complications being included as potential predictors. RESULTS We included 2,264 patients for analysis, of whom 1,267 (56%) were <65 years old (nonelderly), 648 (28.6%) were 65-79 years old (elderly), and 349 (15.4%) were ≥80 years old (super-elderly). Advanced age was a significant predictor of 30-day postoperative mortality, and to a lesser extent postoperative morbidity. Among those patients ≥65 years old, super-elderly age classification remained a significant predictor of mortality after adjustment for the presence or absence of postoperative complications. Mortality among elderly and super-elderly patients was greatest in the setting of specific complications, such as septic shock, prolonged postoperative mechanical ventilation, and acute renal failure. CONCLUSION Advanced age is an independent risk factor for death after emergency surgery for diverticulitis, with mortality being greatest among elderly patients who experience certain postoperative complications. Prevention of these complications should form the cornerstone of initiatives designed to lower the mortality associated with emergency surgery in elderly patients.

The Volume-Outcomes Relationship for United States Level I Trauma Centers

BACKGROUND Previous studies of the center volume-outcomes relationship for severe trauma care have yielded conflicting findings regarding the presence or nature of such a relationship. Few studies have confined their analysis to Level I centers. METHODS We performed a retrospective analysis of severely injured adults treated from 2001 through 2006 in United States Level I trauma centers using data from the National Trauma Data Bank version 7.1. The post-injury in-hospital mortality rates for patients treated at high- or medium-volume Level I trauma centers were compared with the rates for patients treated at low-volume Level I centers before and after adjustment for patient demographic and injury characteristics. Subgroup comparisons were performed for those Level I centers with and without American College of Surgeons (ACS) verification of Level I designation. RESULTS Overall, medium-volume Level I trauma centers had significantly lower mortality than low-volume centers (14.3% versus 15.6%), both before and after adjustment for patient demographic and injury characteristics. Of those trauma centers without ACS verification of Level I designation, high-volume centers had significantly greater mortality than low-volume centers. CONCLUSIONS Our findings support the current utilization by the American College of Surgeons of minimum annual volume requirements for the verification of Level I trauma center designation, and suggest that the presence of such verification may enable Level I centers to effectively manage high volume of severely injured adult patients.

Surgical trainee participation during infrainguinal bypass grafting procedures is associated with increased early postoperative graft failure

OBJECTIVE This study was conducted to determine the potential effect of surgical trainee participation during infrainguinal bypass procedures on postoperative graft patency rates. METHODS Data from the National Surgical Quality Improvement Program (NSQIP) Participant User Files from 2005 through 2009 were retrospectively reviewed, using propensity score matching, to identify all patients undergoing infrainguinal bypass grafting procedures, excluding those who had prior operation ≤30 days of the index procedure. A separate analysis was performed on a subset of procedures from the entire NSQIP sample that was matched on propensity for intraoperative surgical trainee participation. The primary predictor variable was intraoperative surgical trainee participation. The main outcome measure was the 30-day postoperative graft failure rate. RESULTS For the entire sample of 14,723 NSQIP patients undergoing infrainguinal bypass grafting, 30-day graft failure rates were significantly higher when a surgical trainee participated (5.8%) vs without participation (3.9%; P < .0001). For the cohort of 9234 patients matched on their propensity for intraoperative trainee participation, this difference in graft failure rate remained significant (5.0% with participation vs 4.0% without participation; P = .02). CONCLUSIONS Surgical trainee participation is an independent risk factor for technical failure after infrainguinal bypass grafting. Prospective evaluation is needed to determine the cause of this increase in graft failure rates for procedures that involve surgical trainees.

The Impact of Functional Dependency on Outcomes After Complex General and Vascular Surgery

OBJECTIVE To describe the outcomes of functionally dependent patients who undergo major general or vascular surgery and to determine the relationship between functional health status and early postoperative outcomes. BACKGROUND In contrast to frailty, functional health status is a relatively easy entity to define and to measure and therefore may be a more practical variable to assess in patients who are being considered for major surgery. To date, few studies have assessed the impact of functional health status on surgical outcomes. METHODS Patients undergoing 1 of 10 complex general or vascular operations were extracted from the 2005 to 2010 America College of Surgeons National Surgical Quality Improvement Program database. Propensity score techniques were used to match patients with and without preoperative functional dependency on known patient- and procedure-related factors. The postoperative outcomes of this matched cohort were then compared. RESULTS A total of 10,246 functionally dependent surgical patients were included for analysis. These patients were more acutely and chronically ill than functionally independent patients, and they had higher rates of mortality and morbidity for each of the 10 procedures analyzed. Propensity-matching techniques resulted in the creation of a cohort of functionally independent and dependent patients who were well matched for known patient- and procedure-related variables. Dependent patients from the matched cohort had a 1.75-fold greater odds of postoperative death (95% confidence interval: 1.54-1.98, P < 0.0001) than functionally independent patients. CONCLUSIONS Preoperative functional dependency is an independent risk factor for mortality after major operation. Functional health status should be routinely assessed in patients who are being considered for complex surgery.