Ann Walia

Pathology of fatal perioperative myocardial infarction : implications regarding pathophysiology and prevention

The aim of this study was to determine the pathology of fatal postoperative myocardial infarction (MI) and compare it with that of non-operative myocardial infarction. Histopathological analyses of coronary arteries and myocardium were performed on autopsy heart specimens (n = 67), and clinical attributes were studied. Findings of perioperative MI (n = 42) were compared to those of non-perioperative MI (n = 25). Significant atherosclerotic obstruction (> 50% cross-sectional narrowing) was observed in the majority of patients (93%). Left main (> 50% cross-sectional narrowing) and/or three-vessel coronary artery disease were especially common (44%) in this group. Evidence of unstable plaques with disruption was noted in 55% of perioperative MI patients (n = 23); plaque hemorrhage was found in 45% (n = 19). Predicting the site of infarction based on severity of underlying stenosis would have been unsuccessful in more than half the patients in both perioperative and nonoperative MI groups. Clinical profiles of the patients in the two groups were similar in terms of prior cardiac history, gender and age. Fatal perioperative MI occurs predominantly in patients with multivessel coronary disease, especially left main and three-vessel disease. The severity of preexisting underlying stenosis did not predict the resulting infarct territory. Evidence of acute plaque disruption in the infarct-related artery is common. Perioperative MIs have similar coronary artery pathology to non-operative MIs with regard to coronary plaque hemorrhage, rupture, and thrombus formation and probably occur by a similar mechanism.

Acute kidney injury during liver transplantation as determined by neutrophil gelatinase‐associated lipocalin

Acute kidney injury (AKI) has significant prognostic implications for long‐term outcomes in patients undergoing liver transplantation. In several retrospective studies, perioperative variables have been associated with AKI. These variables have been mainly associated with changes in creatinine concentrations over several days or months post‐transplantation. To better define AKI, new markers have become available that help to identify patients at risk for renal injury within hours of a triggering insult. We prospectively enrolled liver transplant patients at our institutions to evaluate neutrophil gelatinase‐associated lipocalin (NGAL), a marker of early renal injury, as a surrogate for AKI in patients undergoing liver transplantation. Blood was prospectively collected at predetermined time points from 59 patients at 2 institutions. The electronic anesthesia records and the hospital computer data system were reviewed for perioperative variables. Data collection included patient demographics, intraoperative variables such as fluid management, transfusion requirements, hemodynamics, and urine output. Subsequently, patients were grouped according to the presence of risk for developing AKI as defined by the RIFLE (risk, injury, failure, loss, and end‐stage kidney disease) criteria. The difference between the NGAL concentration 2 hours after reperfusion and the baseline NGAL concentration was predictive of AKI in all patients, including patients with preexisting renal dysfunction. In patients with creatinine concentrations less than 1.5 mg/dL, a single NGAL determination 2 hours after reperfusion of the liver was associated with the development of AKI. Total occlusion of the inferior vena cava was associated with AKI. In conclusion, NGAL concentrations obtained during surgery were highly associated with postoperative AKI in patients undergoing liver transplantation. These findings will allow the design of larger interventional studies. Our findings regarding the impact of surgical techniques and glucose require validation in larger studies. Liver Transpl 15:1852–1860, 2009.

A multicenter evaluation of safety of early extubation in liver transplant recipients

Small single‐institutional studies performed prior to the introduction of organ allocation using the Model for End‐Stage Liver Disease (MELD) suggest that early airway extubation of liver transplant recipients is a safe practice. We designed a multicenter study to examine adverse events associated with early extubation in patients selected for liver transplantation using MELD score. A total of 7 institutions extubated all patients meeting study criteria and reported adverse events that occurred within 72 hours following surgery. Adverse events were uncommon: occurring in only 7.7% of 391 patients studied. Most adverse events were pulmonary or surgically related. Pulmonary complications were usually minor, requiring only an increase in ambient oxygen concentration. The majority of surgical adverse events required additional surgery. Analysis of a limited set of perioperative variables suggest that blood transfusions and technical factors were associated with an increased risk of adverse events. In conclusion, while early extubation appears to be safe under specified circumstances, there are performance differences between institutions that remain to be explained. Liver Transpl 13:1557–1563, 2007.

Anesthesia for liver transplantation in United States academic centers: intraoperative practice

STUDY OBJECTIVE To determine current practice patterns for patients receiving liver transplantation. DESIGN International, web-based survey instrument. SETTING Academic medical centers. MEASUREMENTS Survey database responses to questions about liver transplant anesthesiology programs and current intraoperative anesthetic care and resource utilization were assessed. Descriptive statistics of intraoperative practices and resource utilization according to the size of the transplant program were recorded. MAIN RESULTS Anesthetic management practices for liver transplantation varied across the academic centers. The use of cell salvage (Cell Saver®), transesophageal echocardiography, thrombelastography, and ultrasound guidance for catheter placement varies among institutions. CONCLUSION Effective practices and more evidence-based intraoperative management have not yet been applied in many programs. Many facets of perioperative liver transplantation anesthesia care remain underexplored.

Liver Transplantation Outcome in Patients with Angiographically-Proven Coronary Artery Disease: A Multi-Institutional Study

Over the last decade the age of liver transplant (LT) recipients and the likelihood of coronary artery disease (CAD) in this population have increased. There are no multicenter studies that have examined the impact of CAD on LT outcomes. In this historical cohort study, we identified adult LT recipients who underwent angiography prior to transplantation at seven institutions over a 12‐year period. For each patient we recorded demographic data, recipient and donor risk factors, duration of follow‐up, the presence of angiographically proven obstructive CAD (≥50% stenosis) and post‐LT survival. Obstructive CAD was present in 151 of 630 patients, the CAD(+) group. Nonobstructive CAD was found in 479 patients, the CAD(−) group. Patient survival was similar for the CAD(+) group (adjusted HR 1.13, CI = [0.79, 1.62], p = 0.493) compared to the CAD(−) group. The CAD(+) patients were further stratified into severe (CADsev, >70% stenosis, n = 96), and moderate CAD (CADmod, 50–70% stenosis, n = 55) groups. Survival for the CADsev (adjusted HR = 1.26, CI = [0.83, 1.91], p = 0.277) and CADmod (adjusted HR = 0.93, CI = [0.52, 1.66], p = 0.797) groups were similar to the CAD(−) group. We conclude that when current CAD treatment strategies are employed prior to transplant, post‐LT survival is not significantly different between patients with and without obstructive CAD.

Water warming garment versus forced air warming system in prevention of intraoperative hypothermia during liver transplantation: a randomized controlled trial [ISRCTN32154832].

BackgroundThe authors compared two strategies for the maintenance of intraoperative normothermia during orthotopic liver transplantation (OLT): the routine forced-air warming system and the newly developed, whole body water garment.MethodsIn this prospective, randomized and open-labelled study, 24 adult patients were enrolled in one of two intraoperative temperature management groups during OLT. The water-garment group (N = 12) received warming with a body temperature (esophageal) set point of 36.8°C. The forced air-warmer group (N = 12) received routine warming therapy using upper- and lower-body forced-air warming system. Body core temperature (primary outcome) was recorded intraoperatively and during the two hours after surgery in both groups.ResultsThe mean core temperatures during incision, one hour after incision and during the skin closing were significantly higher (p < 0.05, t test with Bonferroni corrections for the individual tests) in the water warmer group compared to the control group (36.7 ± 0.1, 36.7 ± 0.2, 36.8 ± 0.1 vs 36.1 ± 0.4, 36.1 ± 0.4, 36.07 ± 0.4°C, respectively). Moreover, significantly higher core temperatures were observed in the water warmer group than in the control group during the placement of cold liver allograft (36.75 ± 0.17 vs 36.09 ± 0.38°C, respectively) and during the allograft reperfusion period (36.3 ± 0.26 vs 35.52 ± 0.42°C, respectively). In addition, the core temperatures immediately after admission to the SICU (36.75 ± 0.13 vs 36.22 ± 0.3°C, respectively) and at one hr (36.95 ± 0.13 vs 36.46 ± 0.2°C, respectively) were significantly higher in the water warmer group, compared to the control group, whereas the core temperature did not differ significantly afte two hours in ICU in both groups.ConclusionsThe investigated water warming system results in better maintenance of intraoperative normothermia than routine air forced warming applied to upper- and lower body.

The evolution of liver transplantation practices.

Purpose of reviewOver the last 40 years, liver transplantation developed from a compassionate attempt to save the lives of patients with end stage liver disease into a sophisticated therapy, for which 1-year survival rates now approach 90%. To understand the evolution of anesthetic perioperative care, its origin needs to be considered. The implications of this evolution on patient outcomes are important and have not been comprehensively reviewed. This article attempts to fill this gap. Recent findingsPolicies for allocating organs continue to evolve in order to better serve those in greatest need as more reliable predictors of pretransplant mortality emerge. Novel approaches to increase the number of organs available for transplantation include donation after cardiac death, living donation and extending the criteria for organ acceptance. Progress in intraoperative hemostatic management and blood loss control, understanding renal physiology, and early extubation protocols are improving outcomes, and contribute to the slowly expanding evidence base for anesthetic perioperative care in liver transplantation. SummaryThe evidence for perioperative best practices in liver transplantation is at a nascent stage. Increased multicenter and international collaborative research in perioperative anesthetic care of liver transplant patients is needed to extend this body of knowledge required to improve transplant outcomes.

Anesthesia for liver transplantation in US academic centers: Institutional structure and perioperative care†

Investigators at a single institution have shown that the organization of the anesthesia team influences patient outcomes after liver transplant surgery. Little is known about how liver transplant anesthesiologists are organized to deliver care throughout the United States. Therefore, we collected quantitative survey data from adult liver transplant programs in good standing with national governing agencies so that we could describe team structure and duties. Information was collected from 2 surveys in a series of quantitative surveys conducted by the Liver Transplant Anesthesia Consortium. All data related to duties, criteria for team membership, interactions/communication with the multidisciplinary team, and service availability were collected and summarized. Thirty‐four of 119 registered transplant centers were excluded (21 pediatric centers and 13 centers not certified by national governing agencies). Private practice sites (26) were later excluded because of a poor response rate. There were minimal changes in the compositions of the programs between the 2 surveys. All academic programs had distinct liver transplant anesthesia teams. Most had set criteria for membership and protocols outlining the preoperative evaluation, attended selection committees, and were always available for transplant surgery. Fewer were involved in postoperative care or were available for patients needing subsequent surgery. Most trends were associated with the center volume. In conclusion, some of the variance in team structure and responsibilities is probably related to resources available at the site of practice. However, similarities in specific duties across all teams suggest some degree of self‐initiated specialization. Liver Transpl, 2012.

Director of anesthesiology for liver transplantation: Existing practices and recommendations by the united network for organ sharing

A new Organ Procurement and Transplantation Network/United Network for Organ Sharing bylaw recommends that all centers appoint a director of liver transplant anesthesia with a uniform set of criteria. We obtained survey data from the Liver Transplant Anesthesia Consortium so that we could compare existing criteria for a director in the United States with the current recommendations. The data set included responses from adult academic liver transplant programs before the new bylaw. The respondent rates were within statistical limits to exclude sampling bias. All centers had a director of liver transplant anesthesia. The criteria varied between institutions, and the data suggest that the availability of resources influenced the choice of criteria. The information suggests that the criteria used in the new bylaw reflect existing practices. The bylaw plays an important role in supporting emerging leadership roles in liver transplant anesthesia and brings greater uniformity to the directorship position. Liver Transpl 19:425–430, 2013.

Anesthetic management for liver resection

As a result of advanced improved diagnostic surveillance, better surgical techniques, and improved anesthetic management and perioperative care, hepatic resections have become more common and more complex but with strikingly better outcomes. For nontumorous hepatic masses, only routine preanesthetic assessment is required. Preexisting liver disease warrants careful assessment of coagulation status, pulmonary and renal function, and cardia status. This may include obtaining a room air arterial blood gas sample and an echocardiogram in addition to the routine preoperative tests. The site and volume of planned resection must be carefully assessed in the preoperative period. This, in addition to the patient’s comorbidities, will determine the extent of invasive monitoring that is required. Previous history of abdominal surgery may increase intraoperative blood loss. Recent data suggest that there has been a marked decrease in transfusion rate in patients undergoing liver resections. More than 60% of the patients do not require blood transfusion, 80% of the patients transfused receive less than 6 units of packed red cells, and only 2% of the patients require greater than 10 units of blood. Blood transfusion has been cited as an independent predictor of operative mortality, major complications, and length of hospital stay. Patients requiring no transfusions had a 1% to 2% mortality, those receiving 1 to 2 units of packed red blood cells had a similar mortality of 2.5% but those who received greater than 2 units of blood had a mortality rate of 11%. Most intraoperative and postoperative complications have been reported during resection of large tumors, particularly in the right lobe or tumors located near or invading the inferior vena cava, the portal veins, or the cavoportal junction. In addition, total vascular occlusion and combined organ surgery and repeat abdominal surgery can lead to sudden or protracted bleeding with intraoperative hemodynamic compromise and increased incidence of air embolism.