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Anesthesia for liver transplantation in US academic centers: Institutional structure and perioperative care†
Article first published online: 29 MAY 2012
Copyright © 2012 American Association for the Study of Liver Diseases
Volume 18, Issue 6, pages 737–743, June 2012
How to Cite
Walia, A., Mandell, M. S., Mercaldo, N., Michaels, D., Robertson, A., Banerjee, A., Pai, R., Klinck, J., Weinger, M., Pandharipande, P. and Schumann, R. (2012), Anesthesia for liver transplantation in US academic centers: Institutional structure and perioperative care. Liver Transpl, 18: 737–743. doi: 10.1002/lt.23427
This study was supported by an educational grant from the Department of Anesthesiology at Vanderbilt University Medical Center (Nashville, TN).
- Issue published online: 29 MAY 2012
- Article first published online: 29 MAY 2012
- Accepted manuscript online: 12 MAR 2012 05:53AM EST
- Manuscript Accepted: 29 FEB 2012
- Manuscript Received: 30 SEP 2011
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. © 2012 AASLD.
Government oversight policies guide health care practitioners to use evidence-based medical paradigms.1 The aim is to reduce the number of adverse events and eliminate the unnecessary use of resources. The transplant community uses this approach to make objective decisions. Committees rely extensively on peer-reviewed evidence to develop policies that affect the delivery of care. Individual and institutional transplant practices must adhere to policies/bylaws established by the United Network for Organ Sharing (UNOS), a self-governing organization that functions under the auspices of the federal government.
The bylaws are designed to ensure that all patients receive comprehensive care. They address issues influencing how interdisciplinary transplant teams are organized. The bylaws provide explicit criteria about issues such as the minimum level of competency, the continuity of care, the availability of personnel, and the presence of ancillary resources. These criteria are enacted at the institutional level, and compliance is monitored.1
In contrast, published data about the efficacy of various transplant anesthesia practices are sparse, and there are few UNOS bylaws that influence how transplant anesthesia care is delivered.1, 2 There are no binding rules that specify levels of competency or guarantee the continuity of care by anesthesia providers. To date, only 1 policy has been developed for the practice of liver transplant anesthesia, and this is simply a recommendation that all programs have a service director.1, 2 The remaining bylaw states only that anesthesia services must be available. Thus, there is no oversight of liver transplant anesthesia care. In contrast to surgical and medical transplant practices, there is no shared mechanism for assessing efficacy or quality. Without evidence or oversight, personal and institutional preferences must play large roles in how anesthesia care is delivered to transplant patients.3, 4
These issues would not be important if anesthesia care had little effect on transplant patient outcomes. However, there is evidence that anesthesia care makes a significant difference.5-7
Outcomes were better and fewer resources were used when anesthesia was administered by a tightly knit team of physicians who were experienced in the care of liver transplant patients.5 The investigators thought that the better outcomes were due to several characteristics of the practice: the formation of a distinct anesthesia transplant team whose focus was liver transplant care, additional education, and the integration of the team members into the larger multidisciplinary transplant team.
This hypothesis is supported by evidence from other transplant centers showing an association between evidence-driven care and the use of focused teams during transplant recipient care.8 Anesthesia teams specializing in the care of transplant patients were able to introduce and systematically test new practices for outcomes. The decision to incorporate practices at these sites was based on evidence rather than empiric reasoning. These studies provide additional evidence that qualities facilitated by an anesthesia team structure are linked to recipient outcomes.9 To date, however, there is no information about the number of institutions with structured teams of anesthesia providers, their financial support, or the rules used for membership and availability.
In view of these findings, we hypothesized that liver transplant anesthesia practices are diverse and are determined by factors that may vary with the site of practice. To test our hypothesis, we collected quantitative survey data from liver transplant programs in good standing with national governing agencies. In this article, we report how anesthesia providers organize their personnel to deliver comprehensive care, and we examine descriptive variables related to team structure and function. Survey questions were focused on team duties, the criteria for membership, the availability of services, and the resources used to maintain team structure.
Liver Transplant Anesthesia Consortium (LTrAC)
LTrAC is a self-appointed group of anesthesiologists who shared the task of developing quantitative surveys about liver transplant anesthesia practices. The executive board comprised 4 anesthesiologists from academic institutions in the United States (Vanderbilt University, the University of Colorado, the University of California San Francisco, and Tufts University). There was 1 additional member from the Liver Intensive Care Group of Europe. All executive members were certified in the specialty of anesthesiology and had performed at least 60 liver transplants during the preceding 5 years. These criteria were adapted from the UNOS bylaws outlining minimum competency rules for liver transplant surgeons.1 The project was housed at Vanderbilt University and was funded by the Department of Anesthesiology; the data management and analysis were performed by the Department of Biostatistics.
LTrAC executive board members developed 4 Web-based surveys to collect data about perioperative anesthesia care in liver transplantation. The first and last surveys in the series focused on team structure (the 101 survey) and perioperative care (the 301 survey). The other 2 surveys concentrated on operative practices. Members of the executive board distributed informational flyers about the LTrAC study to promote participation before the surveys were mailed. The flyers were distributed to the American Society of Anesthesiologists and at the International Liver Transplant Congress.
After institutional review board approval was received from Vanderbilt University, an electronic or mail invitation was sent to the anesthesiology departments included in the study. The first survey was distributed to potential participants in 2006. E-mail reminders were sent every 2 weeks for a total of 3 reminders. In the absence of an electronic response, one of the LTrAC board members tried to contact the anesthesiology department by telephone. All data collection was closed in 2009.
All survey questions were 1-dimensional and multiple-choice in design and allowed categorical responses, dichotomous responses (yes or no), or responses with continuous finite numerical information. The study questions were intended to be as inclusive of anesthesia practices as possible, but additional comment sections were integrated to capture unique practices and answers not included in the survey response options. The surveys were tested for clarity and face validity by the research team members.
The census population was composed of all adult liver transplant academic programs that were certified and were in good standing with governing national agencies (the Centers for Medicaid and Medicare and UNOS). Therefore, we excluded all institutions that cared only for pediatric patients and centers that averaged fewer than 10 cases per year for a period of 3 years. The latter are not certified by the Centers for Medicaid and Medicare.10 We categorized anesthesia practices as academic when they were governed by an accredited school of medicine. Anesthesia practices that were self-governing and were not associated with a medical school were designated as private contractors.
The number of transplants performed annually by each center was confirmed with the Scientific Registry of Transplant Recipients.11 All liver transplant programs were categorized according to their annual transplant frequencies as high-volume (>100), medium-volume (50-100), or low-volume centers (10-49). We were unable to find strict criteria defining adult liver transplant case volumes. Investigators have used a range of numbers to describe high- and low-volume programs.12-15 Most of the definitions are empiric, but there is general agreement between studies. Therefore, we chose numerical definitions that were compatible with previously published studies.
Completed surveys were returned directly to the Department of Anesthesiology at Vanderbilt University. The data were extracted, coded, and entered into a database. The data were analyzed for input errors via a sampling of the distribution of responses. All responses that were outside the distribution were examined by 2 investigators for accuracy. Coding frames were used to solve missing values.
All categorical variables were summarized as weighted percentages. Weights were calculated from the number of respondents at each UNOS center. For example, if 2 responses came from the same center, then the weight associated with each would be 0.5. All analyses were performed with the survey package in R 2.11, an open-source statistical program.16-18 Proportions and their confidence intervals (CIs) were computed via the fitting of logistic regression models whose outcome was a single survey question [(1) yes or (0) no], and the adjustment variable (x) was the size (small, medium, or large). The coefficient (b) values and their associated 95% CIs were computed on a log-odds scale and then were retransformed to obtain probability estimates and CIs as follows:
There were 119 centers listed in good standing when the LTrAC 101 and 301 surveys were distributed (Fig. 1). During the 101 survey, 29% of all centers were excluded because they were pediatric practices or had fewer than 10 cases per year during a 3-year period and 3 programs were also excluded because they were undergoing a reorganization. The majority of the 85 programs included in the study were academic centers (69%). There were few changes in the types of clinical practices during the 301 survey. The same centers were excluded from the 301 survey except for 1 program that had reorganized and become associated with a medical school. A second program, which had been a private anesthesia contractor, became an anesthesia group associated with a medical school. This increased the number of academic centers to 61 during the 301 survey (59 for the 101 survey).
We received answers to the LTrAC 101 survey from 42 of the 59 academic centers (71%) and from 3 of the 26 private practice groups (12%). The private practice groups were excluded from further analysis because of the poor response rate. There were 24 small-volume academic programs, 23 medium-volume academic programs, and 12 high-volume academic programs during the LTrAC 101 survey (Fig. 1). The programs that were designated as medium-volume had the highest response rate (82%). These programs were closely followed by high-volume programs (75%). The programs designated as low-volume had a response rate of 58%. Thirty-nine of the 61 eligible academic centers responded to the 301 survey (64%). The sizes of the centers and the response rates remained relatively constant during the LTrAC 301 survey (Fig. 1).
Criteria for Team Membership
All programs included in the survey population had a dedicated team of anesthesiologists who provided care during liver transplantation surgery. At least 64% (95% CI = 49%-77%) of the study samples required additional postresidency training for team membership (Fig. 2). Most large- and medium-volume programs used supervised on-the-job training for liver transplant anesthesia team members. This type of additional training was least frequent at the low-volume centers, at which additional training in cardiovascular or intensive care anesthesia was more often used for membership. A written anesthesia transplant protocol was used at 80% (95% CI = 65%-89%) of the centers (Fig. 2).
Team Availability and Compensation
A callback system was used to ensure that team members at all study sites were always available for liver transplant surgery. However, only a minority of the programs [30% (95% CI = 17%-45%)] called team members back for emergent surgical events occurring within 72 hours of transplant surgery. This increased to 56% (95% CI = 42%-69%) for life-threatening emergencies when the patient was hemodynamically unstable. For both scenarios, the involvement of the team anesthesiologist decreased with increasing center case volume.
Calls were distributed equally among physicians in most of the study centers [83% (95% CI = 69%-92%)]. The method of compensation for this additional work varied among the centers. More than 75% (95% CI = 60%-86%) of the programs used incentives to compensate anesthesiologists for call availability (Fig. 2). These were either direct financial reimbursements or reductions in other work duties. The incentives were subsidized directly by the hospital at 16% (95% CI = 8%-29%) of the responding centers [mostly at medium-volume centers (26%) and at none of the high-volume centers]. The anesthesiology department provided additional payments for call availability at 40% (95% CI = 27%-54%) of the centers.
Team Duties: Perioperative Care
The majority of the anesthesia programs [65% (95% CI = 51%-77%)] participated in patient selection committees. Participation was greater at high-volume centers. However, only 18% (95% CI = 9%-32%) of the centers reported anesthesia attendance at more than 50% of meetings. Few programs [25% 95% CI = (15%-40%)] provided an anesthesiologist with additional time to attend the selection committee.
Liver transplant anesthesiologists performed routine preoperative assessments at all high-volume centers. This was less common at low-volume [86% (95% CI = 56%-97%)] and medium-volume centers [79% (95% CI = 57%-91%)]. Sixty-five percent (95% CI = 52%-77%) of the centers followed a standard protocol for the preoperative assessment.
There were few protocols that included a time interval necessitating the re-evaluation of transplant candidates. Only 16% (95% CI = 8%-29%) of the anesthesia teams reported a systematic approach to the annual reassessment of candidates. Forty percent (95% CI = 27%-54%) of the centers did not perform an additional evaluation after listing, and anesthesiologists at 33% (95% CI = 22%-46%) of the centers were not aware of a reassessment protocol. The remaining centers had mixed practices.
Some programs asked for anesthesia consults by team members when there was a significant change in the health of a patient on the waiting list. Most centers [62% (95% CI = 47%-75%)] reported that an anesthesia consult was requested for less than 25% of the patients who were already on the transplant list. This low consultation rate was most common at the low-volume centers.
The involvement of anesthesia team members in the postoperative care of recipients was low [29% (95% CI = 17%-44%)]. This practice was followed at 42% (95% CI = 23%-64%) of the medium-volume centers and at only 7% (95% CI = 1%-39%) of the low-volume centers (Fig. 2). A team anesthesiologist was involved in the decision to extubate a patient admitted to the intensive care unit at less than 31% (95% CI = 19%-45%) of the programs. An early extubation protocol (defined as extubation within 6 hours of leaving the operating room) was used at 27% (95% CI = 16%-41%) of the centers. This was uncommon [4% (95% CI = 0%-22%)] in low-volume programs and was most used in mid-volume programs [47% (28%-67%)].
Team Interactions and Communication
As reported by other investigators, regular meetings and educational forums were used as surrogate measures of communication.18, 19 There were significant variations in the amount of time that anesthesiologists spent performing activities that intersected with the larger multidisciplinary transplant team. Team anesthesiologists regularly attended multidisciplinary morbidity and mortality conferences at 80% (95% CI = 66%-89%) of all programs; however this varied with the center volume (Fig. 2). Direct communication with a team anesthesiologist about timing or recipient and donor events was consistently provided at 45% of the centers. The transplant coordinator, the surgeon, or both were most frequently involved in this communication.
Departmental liver transplant team meetings occurred in only 56% (95% CI = 41%-69%) of the surveyed programs [most often in high-volume programs: 75% (95% CI = 36%-94%)]. Only 35% (95% CI = 24%-48%) of all programs included in this study reported routine activities that specifically focused on liver transplantation, including journal clubs, grand rounds, and educational curricula for faculty and residents. These activities were more common in medium-volume programs [41% (95% CI = 24%-60%)] and high-volume programs [47% (95% CI = 23%-72%)].
Our study shows that all academic liver transplant programs have distinct anesthesia teams to care for liver transplant recipients, but their criteria for membership and responsibilities are inconsistent. Most conformity between programs was observed in activities based on the initiation of care, such as preoperative evaluations, attendance at selection committees, and availability for transplant surgery. Fewer team members were involved in the extended care of patients (including postoperative care) and were available for patients needing subsequent surgery. Trends in our data were associated with the center volume. This suggests that the choice of some practices is currently influenced by the resources available at each institution.
The findings of this study are limited to anesthesia practices of adult programs associated with a medical school. We anticipated that the surveys would capture a large amount of variance in practice patterns.3, 20, 21 Therefore, exclusions were used to eliminate variables in the data set that could be related to factors other than anesthesia practices. Pediatric programs were excluded because the case volumes of all institutions are substantially less than the case volumes of adult programs.11 Furthermore, additional certification in pediatric practice is not uniformly applied at all institutions.22
We also excluded all programs not in good standing or certified by national agencies because we were unable to determine how this would affect transplant practices. Only 12% of the programs with private contractors responded to the LTrAC survey. These programs were also dropped from the study because we could not determine whether this caused accidental sampling bias.23 Despite the limited nature of our study population, the data still describe the practices of the majority of all adult transplant centers (69%).
All programs included in the study had a distinct team of anesthesiologists who provided exclusive care for liver transplant surgery. The cost of the additional activities was primarily supported by the department of anesthesiology. This suggests the existence of an informal consensus in US adult academic anesthesia departments that care during liver transplantation is different from other types of care in the operating room.24
The use of additional postresidency training as a criterion for team membership in most programs supports this line of reasoning. Although this opinion has been previously expressed by individual anesthesiologists, our findings show that this is a common viewpoint.15, 24
There is currently no evidence that indicates how additional anesthesia training influences transplant patient outcomes. Indirect findings, however, show that additional anesthesia education and experience are characteristics in a cluster of traits associated with better liver transplant outcomes.5 These observations are congruent with evidence supporting the use of subspecialization in multiple areas of medicine.25 These findings also support the use of educational and experiential criteria established by UNOS and the American Society of Anesthesiologists for the newly recommended position of director of liver transplant anesthesia services.
Anesthesia teams shared similarities in their duties that were associated with the initiation of care. All anesthesia teams had a mechanism to ensure that a member was always available for transplant surgery. Preoperative evaluations and attendance at the selection committee meeting were 2 additional activities that were performed at the majority of the transplant centers.
The data show that anesthesia teams at few study sites provided continuity of care extending beyond the initial evaluation and the immediate postoperative period. Team anesthesiologists at a minority of the programs were available to take patients back for additional surgery, perform evaluations after patients had been on the wait list, or provide input about postoperative care. These practices are substantially different from the practices of most other members of multidisciplinary transplant teams.9, 26, 27
Investigators define continuity of anesthesia care as a preoperative evaluation, intraoperative management, and a postoperative visit by a single provider.28 Therefore, the majority of the perioperative anesthesia transplant practices conformed to accepted general anesthesia duties consistent with continuity of care. There is a body of evidence from other specialties that extended continuity of care improves outcomes.25, 29 Deductive reasoning suggests that more inclusive and extended practices among liver transplant anesthesiologists could improve outcomes. However, there is currently no evidence to support or refute this hypothesis.
Most of our observations were associated with the case volume. The case volume influences the use of resources.30 This may explain some of the previously reported variance in liver transplant anesthesia resource utilization.3 It may also help explain the volume trends observed in our data. For example, we found that all high-volume centers used on-the-job training for team membership criteria. In contrast, this was rare at low-volume centers, which had fewer cases to use for teaching. In comparison with larger teams, fewer low-volume centers provided postoperative care or participated in activities that intersected with the larger multidisciplinary team. Our data suggest that department of anesthesia resources used for liver transplantation, such as personnel and financial support, could influence the ways in which teams are organized and the type of duties that are performed. We suggest that this issue needs to be further evaluated to ensure that quality is maintained in this particular model of health care delivery.
There are several limitations to our study. The LTrAC surveys were designed to collect and catalogue anesthesia liver transplant practices. The surveys were not hypothesis-driven, so the data are primarily descriptive. Because there was no mechanism for conducting an open systematic inquiry, it was not possible to test hypotheses generated from the data. This type of limitation is found in most other quantitative surveys. However, these data give us the first picture of the current organization of anesthesia liver transplant practices and the institutional processes used to deliver care in the United States, and they provide descriptive evidence for future policy development. These data should help us to determine whether specific changes in the organization or structure of anesthesia care are feasible and practical. We also suggest that the variability in the data set can be used to identify areas of practice that need timely attention.
The data describe only adult academic practices. We cannot make inferences about programs not included in the survey population. Furthermore, the data describe only the frequency of practices outlined in the survey. Although the survey questions were as inclusive as possible, they were categorical and were not structured to explore the reasons that health care providers chose these practices. Our survey findings, therefore, do not explain why anesthesiologists adopted specific practices. We think that the reasoning underlying these decisions would be informative.
In conclusion, our findings represent practices from the majority of adult liver transplant programs. The programs shared a number of similarities, all had distinct team anesthesiologists who provided exclusive care for transplant surgery, and most performed activities involved in the initiation of care. The largest variance was observed in extended care because these practices were used by the minority of the study sites. Preliminary data suggest that some of these differences could be related to the resources available at each institution.
- 1United Network for Organ Sharing. http://www.unos.org. Accessed February 2012.
- 2American Society of Anesthesiologists. Guidelines for director of liver transplant anesthesia. http://www.asahq.org/For-Members/Clinical-information/∼/media/For%20Members/documents/Standards%20Guidelines%20Stmts/Liver%20Transplant%20Anesthesia.ashx. Accessed February 2012.
- 7Quality in anesthetic management during hepatic transplant. Hepatic Transplant Anesthesia Group [in Spanish]. Rev Esp Anestesiol Reanim 1996; 43: 354-359., , .
- 10United Network for Organ Sharing. Attachment I to appendix B of UNOS bylaws. http://www.unos.org/docs/Appendix_B_AttachI_XIII.pdf. Accessed February 2012.
- 11Scientific Registry of Transplant Recipients. http://www.srtr.org. Accessed February 2012.
- 16Analysis of complex survey samples. J Stat Softw 2004; 9: 1-19..
- 17R Development Core Team. R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing; 2010.
- 18Complex Surveys: A Guide to Analysis Using R. Hoboken, NJ: John Wiley & Sons; 2010..