M.S. Gwak

The Relationship Between Inhalational Anesthetic Requirements and the Severity of Liver Disease in Liver Transplant Recipients According to Three Phases of Liver Transplantation

PURPOSE Orthotopic liver transplantation (OLT) patients are known to show decreased intraoperative anesthetic requirements compared with patients undergoing other liver surgeries. The aim of this study was to determine the relationship between inhalational anesthetic requirements and the severity of liver disease among OLT patients. METHODS Fifty patients undergoing first living donor OLT were divided into 2 groups: model for end-stage liver disease (MELD) score<20 (low-MELD group; n=25) versus, MELD score>or=20 (high-MELD group; n=25). Anesthesia was maintained with desflurane and inspired concentration was titrated to maintain the bispectral index between 40 and 50. Neither intraoperative opioid nor epidural or intrathecal analgesia was used. End-tidal desflurane concentration (ETdes) was measured every 5 minutes and averaged in 30-minute intervals. These values were divided into 3 phases: preanhepatic (P 0.5 hour, P 1 hour, and P 1.5 hours), anhepatic (A 0.5 hour, A 1 hour, A 1.5 hours, and A 2 hours), and postreperfusion (R 0.5 hour, R 1 hour, R 1.5 hours, R 2 hours, R 2.5 hours, and R 3 hours). Results were compared between the 2 groups. RESULTS The demographic and intraoperative data were similar between the 2 groups. ETdes to maintain comparable anesthetic depth was significantly lower during the preanhepatic and anhepatic phases in the high-MELD than the low-MELD group, but there was no significant difference during the postreperfusion period. CONCLUSIONS OLT patients with high MELD scores showed less inhalational anesthetic requirements during the preanhepatic and the anhepatic periods than those with low MELD scores.

Which Score System Can Best Predict Recipient Outcomes after Living Donor Liver Transplantation

INTRODUCTION Many scoring systems have been suggested to predict the outcomes of deceased donor liver transplantations. The aims of this study were to compare the Model for End-Stage Liver Disease (MELD) score with respect to other scores among patients who underwent living donor liver transplantation (LDLT) seeking to evaluate the best system to correlate with postoperative outcomes after LDLT. METHODS We analyzed retrospectively data from 202 adult patients who underwent LDLT from January 2008 to July 2010. We calculated preoperative MELD, MELD-sodium, MELD to serum sodium ratio (MESO), integrated MELD, United Kingdom MELD, Child-Turcotte-Pugh, Acute Physiology and Chronic Health evaluation II (APACHE II), and Sequential Organ Failure Assessment (SOFA) scores in all patients. We analyzed the correlation of each score with postoperative laboratory results, as well as survival at 1, 3, 6 and 12 months after LDLT. RESULTS There was significant positive correlation between all scores and peak total bilirubin during the first 7 days after LDLT. The MELD score showed the greatest correlation with peak total bilirubin (r=0.745). APACHE II and SOFA scores at 6 months and 1 year after LDLT and MESO score at 1 year after LDLT showed acceptable discrimination performance {area under the receiver operating characteristic curves (AUC)>0.7, while other scoring systems showed poor discrimination. However, the AUCs of each score were not significantly different from the MELD score AUC. CONCLUSION The MELD score most correlated with total bilirubin after LDLT, while the APACHE II and SOFA scores seemed to correlate with mortality after LDLT.

The protective effect of ischemic preconditioning against hepatic ischemic-reperfusion injury under isoflurane anesthesia in rats.

PURPOSE Apoptosis is a central mechanism of ischemic-reperfusion injury (IRI) to the liver. Among the methods to reduce IRI, ischemic preconditioning (IP) has been shown to confer protection. Therefore, the aim of this study was to determine if IP conferred protection against hepatic IRI under isoflurane anesthesia in rats and to investigate underlying protective mechanisms. MATERIALS AND METHODS Twenty-three rats weighing 270 to 300 grams were randomly divided into three groups: (1) the sham operated group (n = 5); (2) the non-IP group (n = 9; 45 minutes of hepatic ischemia followed by 2 hours of reperfusion); and (3) the IP group (n = 9); IP induced by 10 minutes of hepatic ischemia followed by 15 minutes of reperfusion before 45 minutes of prolonged hepatic ischemia). Anesthesia was maintained with isoflurane (1.5%). We compared the degrees of hepatic injury and expressions of B cell lymphoma 2 (Bcl-2) and caspase 3 and 8 mRNAs. RESULTS The IP group showed significantly lower levels of aspartate transaminase and alanine transaminase as well as reduced histological grades of hepatocyte injury compared with the non-IP group at 2 hours after reperfusion. At the corresponding time, the Bcl-2 mRNA level was 2-fold higher in the IP group. Caspase 3 mRNA levels were highest in the non-IP group significantly compared with the sham cohort. Similarly, caspase 8 mRNA levels were highest in the Non_IP group albeit not significancely. CONCLUSION IP protected against hepatic IRI under isoflurane anesthesia in rats. The mechanism of protection appeared to involve upregulation of Bcl-2 expression resulting in inhibited apoptosis.

Effect of active airway warming on body core temperature during adult liver transplantation.

INTRODUCTION Active inspired gas humidification (AH) preserves body heat and maintains normothermia intraoperatively. However, it is unclear whether AH shows comparable influences during liver transplantation (OLT), which may be affected by both large internal heat loss and external heat supply. Thus, the aim of this study was to evaluate the effect of AH compared with passive humidification (PH) on body temperature in OLT. MATERIALS AND METHODS Thirty-four adult patients undergoing living donor OLT were randomly enrolled into two groups: those given AH using a heated humidifier (HH group, n = 17) and those using a heat-and-moisture exchanger (HME group, n = 17). Both core and skin temperatures (Tc and Ts), as well as respiratory parameters, including static/dynamic lung compliances and PaO(2), were recorded at predetermined times. RESULTS Both Tc and Ts were consistently higher among the HH versus the HME group after 2 hours of anesthesia. Differences in Tc and Ts between the two groups increased gradually over time. The overall Tc during surgery was higher among the HH than the HME group (P = .023). The incidences of hypothermia were lower in the HH group at 3 hours of anesthesia, 1 and 3 hours of reperfusion, and at the end of surgery (P = .037, 0.024, 0.005, and 0.010 respectively). The duration of hypothermia was lower in the HH than the HME group (3.9 ± 3.5 hours versus 6.7 ± 3.3 hours, P = .025). Both groups showed no significant intraoperative changes in respiratory parameters; there were no postoperative respiratory complications. CONCLUSION Active humidification warms the patients body effectively, lessening the incidence and duration of hypothermia during OLT with no respiratory risks.

The Relationship between Postoperative Intravenous Patient-Controlled Fentanyl Analgesic Requirements and Severity of Liver Disease

PURPOSE Decreased inhalational anesthetic requirements during orthotopic liver transplantation (OLT) have been reported according to the severity of the pre-existent disease as well as decreased opioid requirements thereafter. The aim of the present study was to determine the relationship between postoperative opioid requirements and severity of liver disease among OLT patients. METHODS We retrospectively reviewed 44 recipients who used intravenous fentanyl-based patient-controlled analgesia (PCA) after OLT from November 2009 to May 2010. The severity of liver disease was assessed using the model for end-stage liver disease (MELD) score. Recipients were divided into a low-MELD group (<20; n=30) and a high-MELD group (≥20; n=14). The amounts of PCA infusion and rescue opioid up to 3 postoperative days (POD) were compared between the 2 groups. The intensity of pain at rest and when coughing was assessed using visual analog scale (VAS) scores. RESULTS The cumulative opioid requirements via PCA on POD 1, 2, and 3 were significantly lower in the high-MELD than the low-MELD group. The amounts of rescue opioid were similar between the 2 groups. However, the intensity of pain at both rest and when coughing on POD 1, 2, and 3 were significantly less severe in the high-MELD than the low-MELD group. CONCLUSIONS OLT patients with high MELD scores required less postoperative opioids and experienced less pain than those with low scores. Therefore, postoperative pain control after OLT should be carefully titrated according to the severity of the liver disease.

The Comparison of Femoral and Radial Arterial Blood Pressures During Pediatric Liver Transplantation

BACKGROUND Orthotopic liver transplantation (OLT) is frequently associated with dramatic hemodynamic changes; thus, it is critical to accurately monitor blood pressure. Although comparisons between femoral arterial blood pressure (FABP) and radial arterial blood pressure (RABP) have been reported in adult liver recipients, we compared FABP with RABP in pediatric recipients. METHODS Thirty-five pediatric liver recipients younger than 13 years of age were included in this prospective, observational study. We measured simultaneous FABP and RABP in the femoral and radial arteries at nine time points during the procedure, including: baseline (after anesthetic induction); 1 hour thereafter; 30 minutes after the beginning of the anhepatic period as well as 0, 1, 3, 5, 15, and 60 minutes after graft reperfusion. RESULTS Of the 35 pediatric liver recipients, 2 infants and 1 13-month-old child were excluded from the analysis because of radial arterial catheter malfunction. The remaining 32 patients including 16 infants and 16 children all showed significantly higher systolic and mean FABP than RABP during most stages of pediatric OLT. Overall diastolic FABP measurements were similar to diastolic RABP throughout the study. CONCLUSIONS Systolic and mean FABP were significantly higher than RABP during most stages of pediatric OLT. Radial arterial catheter malfunctions were not uncommon during pediatric OLT. Our results indicated that it is useful to cannulate the femoral artery to accurately and reliably measure arterial blood pressure to detect hemodynamic instability during pediatric OLT.

Preoperative depressed mood and perioperative heart rate variability in patients with hepatic cancer.

STUDY OBJECTIVE How perioperative heart rate variability (HRV) indices differ according to the anxiety or depressed mood of patients scheduled to undergo a major surgical procedure for cancer. DESIGN Prospective observational study. SETTING Operating room. PATIENTS Forty-one male patients between 40 and 70 years of age with hepatocellular carcinoma were included in the final analysis. INTERVENTIONS HRV was measured on the day before surgery (T1), impending anesthesia (T2), and after anesthetic induction (T3). Preoperative anxiety and depressed mood of all patients were evaluated using the State-Trait Anxiety Inventory and Self-Rating Depression Scale (SDS). MEASUREMENTS AND RESULTS HRV was significantly different among T1, T2, and T3. At T2, high frequency (HF) (normalized units of HF [nuHF]) was decreased and low frequency (LF) (normalized units of LF) and LF/HF were increased compared with those at T1 and T3. In the subgroup analysis between high and low SDS groups, high SDS group showed significantly decreased nuHF (P = .035), increased nuLF (P = .039), and increased LF/HF (P = .020) compared to low SDS group at T1. However, these values at T2 and T3 were not different between 2 groups. In analysis within the groups, low SDS group showed significant differences in nuHF, nuLF, and LF/HF among T1, T2, and T3 (P < .05, respectively), but no changes in these values were observed in high SDS group among the 3 different time points. CONCLUSIONS HRV decreased significantly immediately before anesthesia and recovered to baseline with anesthetic induction. Preoperative, more depressed patients showed increased sympathetic tone at baseline and blunted response to impending anesthesia on the HRV measurements.

Comparison of two fluid warming devices for maintaining body core temperature during living donor liver transplantation: Level 1 H-1000 vs. Fluid Management System 2000

Background Rapid fluid warming has been a cardinal measure to maintain normothermia during fluid resuscitation of hypovolemic patients. A previous laboratory simulation study with different fluid infusion rates showed that a fluid warmer using magnetic induction is superior to a warmer using countercurrent heat exchange. We tested whether the simulation-based result is translated into the clinical liver transplantation. Methods Two hundred twenty recipients who underwent living donor liver transplantation between April 2009 and October 2011 were initially screened. Seventeen recipients given a magnetic induction warmer (FMS2000) were matched 1 : 1 with those given a countercurrent heat exchange warmer (Level-1 H-1000) based on propensity score. Matched variables included age, gender, body mass index, model for end-stage liver disease score, graft size and time under anesthesia. Core temperatures were taken at predetermined time points. Results Level-1 and FMS groups had comparable core temperature throughout the surgery from skin incision, the beginning/end of the anhepatic phase to skin closure. (P = 0.165, repeated measures ANOVA). The degree of core temperature changes within the dissection, anhepatic and postreperfusion phase were also comparable between the two groups. The minimum intraoperative core temperature was also comparable (Level 1, 35.6℃ vs. FMS, 35.4℃, P = 0.122). Conclusions A countercurrent heat exchange warmer and magnetic induction warmer displayed comparable function regarding the maintenance of core temperature and prevention of hypothermia during living donor liver transplantation. The applicability of the two devices in liver transplantation needs to be evaluated in various populations and clinical settings.

Analysis of Predictors for Lactate Elimination After Reperfusion in Recipients of Living-Donor Liver Transplantation

BACKGROUND Graft-recipient weight ratio (GRWR) is the only documented predictor that influences the lactate elimination after reperfusion in living-donor liver transplantation (LDLT). This study was performed to investigate the predictors of lactate elimination after reperfusion in recipients of adult LDLT. METHODS The medical records of 159 patients who underwent LDLT were analyzed. Lactate level (mmol/L) was measured from just before the initiation of surgery (P0) and 5, 60, and 120 minutes after reperfusion of graft (R0, R1, and R2, respectively). The change of lactate level after reperfusion was defined as difference between lactate level measured at R0 and R2. Patients were divided into accumulation and elimination groups. Donor and recipient factors were compared between the 2 groups. RESULTS Lactate accumulation occurred in 80 of 159 recipients (50.3%), and elimination occurred in 79 (49.7%). GRWR and Model for End-Stage Liver Disease (MELD) score were higher in the elimination group. Lactate at R0 was lower in the elimination group. CONCLUSIONS Higher GRWR and MELD score and lower lactate level immediate after reperfusion of graft were predictors of lactate elimination after reperfusion during adult LDLT.

Comparison of mixed venous oxygen saturation after in vitro calibration of pulmonary artery catheter with that of pulmonary arterial blood in patients undergoing living donor liver transplantation.

INTRODUCTION Mixed venous saturation (SvO2) reflects the balance between oxygen delivery and consumption throughout the body. A multifunction pulmonary artery catheter (PAC) can monitor continuous SvO2 after in vitro calibration (CSvO2), obviating the need for in vivo calibration with pulmonary arterial blood. In critically ill patients CSvO2 has shown a good correlation with measured SvO2 of pulmonary arterial blood using co-oximetry (MSvO2). The aim of this study was to compare CSvO2 and MSvO2 in liver transplantation (OLT) recipients. METHODS We enrolled 44 OLT recipients for comparison with 24 coronary artery bypass graft (CABG) controls free of end-stage liver disease. After anesthetic induction, the PAC was inserted after in vitro calibration and CSvO2 and MSvO2 simultaneously measured. In OLT recipients, additional measurements of CSvO2 and MSvO2 were performed at anhepatic and postreperfusion phases. Pearsons correlation analysis was used to evaluate the correlation between the 2 measurements. A Bland-Altman analysis was used to determine precision of and bias between the 2 measurements. With ±3% regarded to be interchangeable. RESULTS Cardiac output and intrapulmonary shunt in CABG patients were lower than among OLT recipients. OLT recipients, showed a significant correlation between CSvO2 and MSvO2, but the coefficients were different during the three phases of OLT (r = 0.597, 0.753, and 0.756). In addition, bias values between the two measurements were 6.0%, 6.4%, and 2.9% for the preanhepatic, anhepatic, and postreperfusion phases, respectively, with 29.5%, 31.8%, and 50% of them being interchangeable. In contrast CABG patients showed bias in -0.17% with 75% of measurements interchangeable. CONCLUSION While in vitro calibration of the PAC can be used in CABG patients, MSvO2 is higher than CSvO2 in OLT recipients. Therefore, in vivo calibration with pulmonary arterial blood is necessary for accurate monitoring of SvO2 in OLT recipients.