Designated liver transplant anesthesia team reduces blood transfusion, need for mechanical ventilation, and duration of intensive care

Authors


  • Some of this information was presented at the International Hepato-Pancreato-Biliary Association's 8th World Congress (Mumbai, India, 2008) and at the Joint International ILTS-ELITA-LICAGE Congress (Paris, France, 2008).

It was the area of manufacturing in which the idea of continuous quality improvement (CQI) originated and developed to what we consider a highly efficient model for all industries today.1–6 Since the 1980s, when the cost of healthcare began rising faster in the United States than the cost of living, quality issues have gradually gained importance for the medical industry and the government. Furthermore, a systematic assessment of healthcare by the Institute of Medicine in 1999 revealed shocking discrepancies between outcomes. One of the main findings suggested that, despite having one of the best acute care services in the world, the United States fails to deliver consistent quality. A growing body of research has confirmed the existence of wide variations that are attributable to differences in medical practices and are unrelated to patients' preexisting medical conditions.7 Healthcare leaders recognized long ago that education and continuous systematic development are essential to improving outcome.8–10 To build on the strengths of the current system and address the weakness of inconsistent quality, healthcare organizations have initiated CQI processes with various degrees of success over the last few years.11

Our institution, the University of Wisconsin (UW), is a large transplant center with over 8000 organs transplanted to date, and it is regarded as a pioneer of organ preservation.12 This article describes the decision process, implementation, and results of a newly established dedicated liver transplant anesthesia team since 2003.

Abbreviations

CQI, continuous quality improvement; CREAT, creatinine; CVP, central venous pressure; DF, degree of freedom; FFP, fresh frozen plasma; ICU, intensive care unit; N, sample size; RBC, red blood cell; TEG, thromboelastography; UW, University of Wisconsin; VENT, ventilation.

PATIENTS AND METHODS

After the commitment was made to develop a state-of-the-art transplant anesthesiology division at UW, the CQI plan called for a series of educational, organizational, and clinical changes that were to be gradually introduced in a fashion consistent with the plan-do-study-act cycle.

The first step of the new CQI process focused on education. Creating concentrated subspecialty knowledge was accomplished by the creation of a liver transplant anesthesiology case library and the establishment of a new transplant anesthesia rotation for resident training. Evidence-based guidelines [eg, low central venous pressure (CVP) intraoperative fluid management, thromboelastography (TEG), conservative blood transfusion triggers, systematic use of antifibrinolytics for hyperfibrinolysis, and extubation in the operating room when possible] were published on the departmental intranet for all anesthesia personnel.

Subsequently, we identified a group of 7 faculty volunteers who later became the dedicated liver transplant anesthesia team. None of these individuals completed a formal transplant anesthesia fellowship, but 2 were board-certified in critical care, and more importantly, all were committed to upgrading and maintaining their knowledge on transplant anesthesia. Journal clubs and other regular meetings played a vital role in developing a transplant anesthesia division with clearly stated objectives. In addition to providing clinical care and contributing to educational activities, team members became involved with various perioperative transplant surgery functions, such as patient selection and preoperative screening. Furthermore, anesthesiologists began attending surgical transplant conferences, and transplant surgeons were invited to anesthesia conferences when they dealt with transplantation issues.

To ascertain whether our model has improved outcomes, we have continuously monitored and analyzed patient data since the implementation of the CQI program.

Statistical Methods

We analyzed the use of intraoperative blood transfusion, the need for postoperative mechanical ventilation, and the duration of intensive care stay from 2000 to 2005. In order to compare the values from year to year, linear regression was used, with the period of 2000-2002 used as the baseline. In addition, a series of paired t tests were performed to compare preoperative and postoperative creatinine (CREAT) values by year (2001-2005).

RESULTS

During the period of 2000-2005, the surgical group consisted of the same 3 senior transplant surgeons, and the surgical technique was essentially unchanged. Venovenous bypass was not used in any of these cases. For greater consistency of the studied population, we excluded patients under age 14 and those who had simultaneous liver-kidney transplantation.

Patient demographics (gender, age, height, and weight) and average Model for End-Stage Liver Disease scores [11.3 (2000-2002), 12.4 (2003), 14.1 (2004), and 12.8 (2005)] were similar for the observed time periods. There were no major changes in graft quality either: donation after cardiac death liver frequency was 7.1% (2000-2002), 11.4% (2003), 11.5% (2004), and 9.2% (2005). Intraoperative mortality was rare and sporadic throughout the years: 0.89% (2000-2002), 1.26% (2003), 0% (2004), and 2.3% (2005).

Figures 1 and 2 show the means, standard deviations, and sample sizes for intraoperative red blood cell (RBC) transfusion, fresh frozen plasma (FFP) transfusion, postoperative mechanical ventilation duration, and intensive care unit (ICU) duration by year.

Figure 1.

Blood transfusion during liver transplantation (per case): bar plots of RBC and FFP by year. An asterisk indicates a significant difference from the 2000-2002 value at a significance level of α = 0.05 based on the Wald t test for the respective regression coefficient with adjustments for age, gender, baseline weight, and height. Abbreviations: FFP, fresh frozen plasma; N, sample size; RBC, red blood cell.

Figure 2.

Postoperative recourse utilization: bar plots of VENT and ICU by year. An asterisk indicates a significant difference from the 2000-2002 value at a significance level of α = 0.05 based on the Wald t test for the respective regression coefficient with adjustments for age, gender, baseline weight, and height. Abbreviations: ICU, intensive care unit; N, sample size; VENT, ventilation.

There were significant reductions of RBC transfusion in 2004 [t = −3.19, degree of freedom (DF) = 86, P = 0.0015] and in 2005 (t = −4.89, DF = 86, P < 0.001). Similarly, FFP use was reduced in 2004 (t = −6.40, DF = 86, P < 0.001) and in 2005 (t = −9.47, DF = 86, P < 0.001).

Our success rate of removing the endotracheal tube at the end of surgery before the patient left the operating room increased from 0% (2000-2002) to 56% (2005). In the year 2005, there were statistically significant reductions in mean ventilation (t = −2.14, DF = 80, P = 0.0326) and ICU (t = −2.39, DF = 80, P = 0.0170) durations.

DISCUSSION

It has been a long time since Dr. Thomas Starzl performed the first liver transplant in 1963.13, 14 Currently, nearly 6000 liver transplants are performed in the United States yearly, with a 3-year survival of around 80%. Rapidly changing clinical knowledge has been a major factor in surgical and anesthesia care from the very beginning.15 A review of the anesthesia literature from the 1990s suggests an enormous variability of perioperative care and resource utilization.16

Liver transplant outcome at UW has ranked consistently high on national comparisons since the late 1980s, and the volume of liver transplant cases has increased gradually over time. One-year survival was 88.97% for the patients of the 7/1/2000-12/31/2002 period.12 In the opinion of the Anesthesiology Department, there was no justification for establishing a dedicated liver transplant anesthesiology team as there was no published evidence that specialized anesthesia personnel would improve outcome. By 2003, all 40 faculty anesthesiologists participated in liver transplantation, with approximately 90 cases per year. Surgeons, however, strongly felt that there was a lack of consistency of anesthesia care and that there was no concentrated anesthesia expertise in transplantation. Furthermore, they argued that the large size of the UW anesthesia group was a limiting factor in developing a collaborative relationship between anesthesiologists and surgeons.

It was the University Healthsystem Consortium national transplant benchmarking project in 2003 that became a catalyst for resolving this difference of opinion. The data showed great differences in perioperative practices nationwide and, more importantly for us, significantly higher blood transfusion use for liver transplantation at UW versus the national norm (mean RBC, 17.3 versus 10.2 units).17 Furthermore, the University Healthsystem Consortium named “consistency of practice” and “team approach with ongoing communication” the 2 top priority “project critical success factors.” The survey convinced the Transplant Surgery Division, the Department of Anesthesiology, and the hospital to form an alliance and create a dedicated liver transplant anesthesia team. The goal was to increase perioperative anesthesia involvement with transplant surgery, explore areas to improve care, and optimize resource utilization. Specifically, we aimed to decrease blood product transfusion and shorten ICU stay. Matching the best liver transplantation anesthesia practices worldwide was the ultimate target. The venture took off in late 2003, with the appointment of the Director of Transplant Anesthesia and with retrospective data collection to establish a baseline. In addition, after obtaining institutional review board approval, the Transplant Anesthesia Division gained access to the hospital's transplant database to facilitate monitoring of a broader spectrum of clinical data.

The main steps of organizational, educational, and clinical changes are listed in the Patients and Methods section. However, detailed explanations for our evidence-based clinical changes seem more appropriate in this section. The main difference in this regard was intraoperative fluid management. There were no published liver transplant studies with this specific focus before 2003, but we felt that the evidence from liver resection surgery was compelling and applicable to the pre-anhepatic phase of liver transplantation.18, 19 In particular, we were inspired by the prospective study of Jones et al.,18 which indicated as much as 80% reduction of blood loss when the CVP was maintained at or below 5 cmH2O. We were glad to see Massicotte et al.20 in 2004 reproduce the utility of the low CVP strategy during liver transplantation. It should not come as a surprise that maintaining CVP at less than 5 cmH2O during the pre-anhepatic phase by the limitation of intravenous fluid use became a main goal for our team. Another major change in our approach was the routine use of TEG for coagulation assessment. The evidence was well established in the literature, since Kang et al.21 first observed it in 1985, that TEG use was associated with a 33% reduction of blood and other fluid infusion. Therefore, we incorporated intraoperative baseline and postreperfusion TEG measurements into our clinical practice. Consequently, unlike in previous years at UW, blood transfusion was performed according to goal-directed transfusion triggers, and FFP and RBC units were no longer used as the primary volume expanders.20 A hemoglobin level of 7 to 9 g/dL and a fibrinogen concentration over 100 mg/dL became standardized goals for RBC and cryoprecipitate transfusions.22 At the same time, on the basis of TEG, we aimed to maintain the fibrin formation rate (R) at less than 20 mm and the maximal amplitude (MA) over 45 mm with plasma and platelet administration.23 Subsequently, on the basis of numerous studies showing a significant reduction in blood transfusion with antifibrinolytics, we decided on administering aminocaproic acid or aprotinin to our patients when hyperfibrinolysis (30 minutes after maximal amplitude, lysis above 7.5%) was observed on TEG.24–26

At UW, the main cause of improvement came from a systematic adjustment of clinical care based on published medical evidence. We used the classic CQI model and the plan-do-study-act cycle for the sequential introduction of organizational, educational, and clinical changes. Evidence-based adjustments of clinical guidelines were followed by outcome monitoring and necessary readjustments. We observed a significant reduction of blood product transfusion requirement in the subsequent years. Decreased intraoperative fluid administration improved our ability to discontinue mechanical ventilation immediately after surgery in an increasing portion of cases.27 Patients, on average, progressed faster postoperatively and required a lower acuity of care as reflected in a shortened ICU stay. One-year survival has not changed. A significant reduction of resource utilization on the side of the organization and a shorter ICU stay for the patients are remarkable and encouraging results nonetheless.

Favorable changes were evident to the surgeons, the intensive care providers, and the hospital administration. Positive interactions developed into a self-perpetuating cycle of trust with increasingly efficient communication and mutual respect.

In the end, we included preoperative and postoperative CREAT in our analysis because optimal intraoperative fluid management has been an area of much debate recently for transplant surgeons and anesthesiologists alike (Fig. 3). Low intravascular filling pressure has the advantage of reduced blood loss and a lower blood transfusion requirement during liver surgery. However, the potential for compromised postoperative renal function as a result of restrictive intraoperative fluid administration is a valid concern and deserves a large-scale, prospective, randomized study. Because of this ever-present concern for renal injury, we decided to monitor renal outcome as 1 parameter of the plan-do-study-act cycle, with the intention of correcting our clinical guidelines if this was indicated by our data analysis. In our experience, low intravascular volume did not alter postoperative serum CREAT levels.

Figure 3.

Bar plots of the preoperative and postoperative CREAT averages by year. Abbreviations: CREAT, creatinine; DF, degree of freedom.

At UW, significantly reduced blood transfusion and shorter ICU stay generously rewarded the Anesthesiology Department's efforts of organizing and maintaining a dedicated liver transplant anesthesia team. In addition, the collaborative anesthesia-surgery interactions resulted in a much less tense work environment for all personnel involved in liver transplantation and considerably increased academic productivity for members of the Transplant Anesthesia Division. Our experience may be a valuable example of gradual transformation, based on the CQI principle, for institutions with similar challenges and aspirations.

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