H.-P. Yu

Stroke Volume Variation Derived by Arterial Pulse Contour Analysis Is a Good Indicator for Preload Estimation During Liver Transplantation

BACKGROUND Accurate determination of preload during liver transplantation is essential. Continuous right ventricular end diastolic volume index (RVEDVI) has been shown to be a better preload indicator during liver transplantation than the filling pressures. However, recent evidence has shown that dynamic variables, in this case stroke volume variation (SVV), are also good indicators of preload responsiveness. In this study, we evaluated the correlation between SVV, which we derived from arterial pulse contour analysis and RVEDVI. METHODS In this study, we looked for possible relationships between SVV obtained through FloTrac/Vigileo monitor, central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), and RVEDVI in 30 patients undergoing liver transplantation. Measurements were taken at 11 defined points during different phases across liver transplantation. Each set of measurement was taken during a steady state, which means at least 15 minutes elpased after any changes occured in either the infusion rate of catecholamines or ventilator settings. Pearsons test was used for correlation estimation. RESULTS There was a statistically significant (P<.01) relationship between SVV and RVEDVI with a correlation coefficient of -0.87. The correlations between CVP (r=0.42), PAOA (r=0.46), and RVEDVI were less strong. CONCLUSION We conclude that SVV is a good indicator for preload estimation during liver transplantation. A higher SVV value is associated with a more hypovolemic fluid status.

Cardiac Output Derived From Arterial Pressure Waveform Analysis: Validation of the Third-Generation Software in Patients Undergoing Orthotopic Liver Transplantation

BACKGROUND The upgraded third-generation software (version 3.02) for the FloTrac/Vigileo system has been developed to particularly improve the accuracy of cardiac output (CO) measurements in hyperdynamic conditions. The aim of our study was to compare the CO values obtained using the FloTrac/Vigileo system during orthotopic liver transplantation (OLT) with those obtained in the same circumstances using a Swan-Ganz catheter (bolus thermodilution method). METHODS Twenty consecutive recipients scheduled for OLT were studied. Simultaneous CO values measured by both devices were obtained at 10 predefined time points throughout the surgery. A percentage error of not more than 30% was established as the criterion for device interchangeability. RESULTS A total of 200 paired measurements were obtained. The CO values derived from the FloTrac/Viligeo ranged from 2.8 to 10.9 L/min, with a mean of 5.91±1.81 L/min. The values from bolus thermodilution ranged from 2.2 to 13.2 L/min, with a mean of 6.12±2.07 L/min. The bias was 0.22, and the limits of agreement were -3.13 to 3.56 L/min. The percentage error between the FloTrac/Viligeo and bolus thermodilution measurements was 54.93%. The percentage errors of paired measurements in three surgical phases by subgroup analysis were 43.50% (dissecting phase), 62.9% (anhepatic phase), and 56.05% (reperfusion phase), respectively. CONCLUSION CO measurements obtained using the less invasive arterial waveform FloTrac/Vigileo system upgraded with the third-generation software had poor intraoperative agreement with pulmonary artery thermodilution CO measurements in patients undergoing OLT.

Cardiac output derived from arterial pressure waveform analysis in patients undergoing liver transplantation: validity of a third-generation device.

BACKGROUND Hemodynamic monitoring is essential to a successful liver transplantation procedure. FloTrac, a hemodynamic monitor that uses arterial-waveform-based pulse contour analysis for cardiac output (CO) measurement, has proven useful in many clinical settings. One of the primary foci of FloTracs recent third-generation software upgrade was improving its accuracy in low systemic vascular resistance status. We evaluated the accuracy of the upgraded FloTrac monitor during liver transplantation. MATERIALS AND METHODS Twenty-eight patients undergoing liver transplantation were enrolled in the study. Two sets of CO were measured with a radial arterial line connected to a FloTrac monitor (COFT) and a pulmonary artery catheter connected to a continuous cardiac output Vigilence monitor (COPAC). Simultaneous CO measurement was performed and recorded every 5 minutes throughout the surgery. Bland-Altman analysis was used to estimate the accuracy. The comparative method and reference method were considered interchangeable if the limits of agreement did not exceed a threshold set a priori at the greater of ±1 L/min, or a percentage error of lesser than 30%. RESULTS In all, 3234 paired data were collected. The bias was -0.8 L/min and the limits of agreements were -5.6 to 4.0 L/min. Percentage error was 75%. Regression analysis of the systemic vascular resistance index (SVRI) and the bias between COPAC and COFT showed that the bias was inversely related to the SVRI [r2=0.49; P<.001, y=-32.1983+9.9978 Log(x)]. CONCLUSIONS Despite a software upgrade, the effectiveness of the FloTrac artery-derived cardiac output monitor for CO measurement during liver transplantation remains limited.

Nasogastric tube insertion in anesthetized and intubated patients: a new and reliable method

BackgroundThe “Rusch” intubation stylet is used to make endotracheal tube intubation easy. We designed this study to evaluate the usage of this equipment in the guidance of nasogastric tube (NGT) insertion.MethodsA total of 103 patients, aged 23 to 70 years, undergoing gastrointestinal or hepatic surgeries that required intraoperative NGT insertions were enrolled into our study. The patients were randomly allocated to the control group (Group C) or the stylet group (Group S) according to a computerized, random allocation software program. In the control group, the NGT was inserted with the patient’s head in an intubating position. In the stylet group, the NGT was inserted with the assistance of a “Rusch” intubation stylet tied together at the tips by a slipknot. The success rates of the two methods, the durations of the insertions, and the occurrences of complications were recorded. All of the failed cases in the control group were subjected to the new technique used in the stylet group, and the successful rescue rate was also evaluated.ResultsSuccessful insertions were recorded for 52/53 patients (98.1%) in Group S and for 32/50 patients (64%) in Group C. The mean insertion times were 39.5 ± 19.5 seconds in Group C and 40.3 ± 23.2 seconds in Group S. Successful rescues of failure cases in Group C were achieved in 17/18 patients (94.4%) with the assistance of a “Rusch” intubation stylet.ConclusionsThe “Rusch” intubation stylet-guided method is reliable with a high success rate of NGT insertion in anesthetized and intubated patients.Trial registrationInstitutional Review Board of Chang Gung Memorial Hospital (IRB: 98-2669B) and Australian New Zealand Clinical Trials Registry (ACTRN12611000423910)

Ischemic reperfusion injury-induced oxidative stress and pro-inflammatory mediators in liver transplantation recipients.

OBJECTIVE Liver ischemic reperfusion injury is harmful to transplant recipients, and is associated with postoperative morbidity and mortality. Our study was designed to investigate the oxidative stress and pro-inflammatory mediators in liver transplant recipients. METHODS We prospectively analyzed 14 recipients who underwent liver transplantation by measuring their blood levels of malondialdehyde (MDA) and cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6, at nine time points perioperatively. We also evaluated the correlations between oxidative stress (MDA levels) and the characteristics of the recipient or the donated graft. RESULTS These parameters significantly increased from 1 minute before reperfusion, and the values peaked within 3 to 30 minutes after reperfusion. On the time point at 5 minutes after reperfusion, the MDA levels which were the highest in the recipients correlated with the values of preoperative direct/and total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), model for end-stage liver disease (MELD) score, international normalized ratio (INR), and surgical blood loss. CONCLUSION The levels of MDA, TNF-α, IL-1β, and IL-6 greatly increased with the ischemic reperfusion insult. Recipients with higher values of preoperative direct/and total bilirubin, AST, ALT, MELD score, INR, and surgical blood loss tended to have higher levels of MDA and may suffer more injury from this insult.

Propofol attenuates ischemic reperfusion-induced formation of lipid peroxides in liver transplant recipients.

OBJECTIVE Ischemic reperfusion (IR) injury is known to have an important influence on the success of transplant surgery and the occurrence of complications. Malondialdehyde (MDA) is an intermediate metabolite of lipid peroxidation resulting from IR-induced reactive oxygen species. This study was designed to investigate the protective effects of propofol on IR injury in liver transplant recipients. METHODS We analyzed 19 recipients prospectively by measuring the blood levels of MDA at nine predefined intervals; before induction of anesthesia (baseline, T0), 1 hour after surgical incision (T1), 1 minute before reperfusion (T2), 30 seconds after reperfusion (T3), as well as 1, 3, 5, 30, and 60 minutes thereafter (T4-8). These patients were randomly allocated to two groups. The propofol group received an infusion (2 mg/kg per hr) after an induction bolus (2 mg/kg). The control group was prescribed midazolam (0.2 mg/kg) for induction without intravenous anesthetic infusion for maintenance. RESULTS The highest MDA level occured at T6 in the controls and T7 in the propofol group. Compared with the blood levels at baseline, the MDA levels increased significantly at T2-T8 among controls versus T2, T3, T4, and T7 in the propofol group. Compared to the control group, propofol significantly lowered MDA values at T5-T8. CONCLUSION There were significantly higher MDA levels among the control versus the propofol group at 3, 5, 30, and 60 minutes after reperfusion in liver transplant recipients.

The Ratio of Plasma Neutrophil Gelatinase-Associated Lipocalin Predicts Acute Kidney Injury in Patients Undergoing Liver Transplantation

BACKGROUND Postoperative acute kidney injury (AKI) is associated with high morbidity and mortality after liver transplantation (OLT). Previous studies have shown the value of plasma neutrophil gelatinase-associated lipocalin (NGAL) taken 2 hours after reperfusion of the liver graft as an early marker predicting AKI. The study was performed to determine whether plasma NGAL concentrations obtained as early as 1 hour after reperfusion was predictive of AKI and whether the NGAL ratio was an early predictor for AKI in the first 48 hours after OLT. METHODS Twenty-six liver transplant recipients donated plasma samples for NGAL determinations at induction (T1), at graft reperfusion (T3) as well as after 1 (T4) and hours 2 (T5), and at the end of the surgery (T7). AKI was defined at 48 hours after liver transplantation according to the acute kidney injury network criteria. Predictive ability was assessed using areas under the curve of receiver operator characteristic analyses. RESULTS The area under the curve of the receiver operator characteristics curve of (plasma NGAL concentration at T4)/(plasma NGAL concentration at T1) to predict AKI was 0.717 at T5, 0.765 at T7, 0.714 at T8 (24 hours post-OLT), and 0.781 at T9 (48 hours post-OLT). CONCLUSION The plasma NGAL concentrations taken 1 hour after reperfusion of the liver graft seem to be predictive of AKI; the NGAL changing ratio may be an early predictor for AKI in the first 48 hours after OLT.

The Ratio of Plasma Interleukin-18 Is a Sensitive Biomarker for Acute Kidney Injury After Liver Transplantation

BACKGROUND Acute kidney injury (AKI) is common after liver transplantation (OLT) and is associated with high morbidity and mortality. Previous studies have shown that interleukin-18 (IL-18) levels are associated with AKI. The purpose of this study was to determine whether plasma IL-18 levels were early predictors for AKI after liver transplantation. METHODS Plasma samples were obtained from 26 patients who underwent OLT at induction of anesthesia (T1), 1 hour after the surgical incision (T2), the time of reperfusion (T3), as well as 1 (T4), 2 (T5), and 4 hours (T6) after reperfusion. Samples were also obtained at 24 hours after surgery (T7). The AKI criteria were taken according to the Acute Kidney Injury Network criteria. RESULTS Twelve patients (46%) developed AKI after OLT. The area under the receiver operating curve of plasma IL-18 concentrations (T4/T1) to predict AKI occurrence was 0.842 at T5, 0.905 at T6, 0.726 at T7, and 0.726 at T5 to T7. CONCLUSION Plasma IL-18 concentrations taken 1 hour after reperfusion were predictive of AKI. Therefore, changing IL-18 ratio may be an early predictor for AKI after OLT.

Increased oxidative stress and gut ischemia caused by prolonged pneumoperitoneum in patients undergoing robot-assisted laparoscopic radical prostatectomy

OBJECTIVE To investigate changes in plasma oxidative stress markers associated with prolonged pneumoperitoneum during robot-assisted laparoscopic radical prostatectomy (RALP). METHODS In all, patients of ASA Physical Status II-III who intended to undergo RALP were enrolled in the study. Arterial plasma levels of malondialdehyde (MDA) and intramucosal pH were measured 1 minute before and at 1 hour, 2 hours, 3 hours, and 4 hours after the introduction of pneumoperitoneum at an insufflation pressure of 15 mmHg; likewise, they were again measured every 10 minutes after deflation for 60 minutes, at 2 hours and 12 hours after deflation. RESULTS The mean duration of pneumoperitoneum was around 4 hours. After induction of pneumoperitoneum, the MDA concentrations were significantly elevated at various time points as compared with the preinsufflation value. Significant increase of MDA value was noted also 30 minutes after deflation as compared with the pre-deflation levels. The intramucosal pH value decreased significantly after CO(2) insufflation compared with the preinsufflation values. It also increased significantly 2 hours after CO(2) deflation as compared with the pre-deflation values. CONCLUSION A prolonged pneumoperitoneum in RALP results in decreased splanchnic blood flow. Pneumoperitoneum itself produces oxidative stress, and ischemia-reperfusion model after deflation of pneumoperitoneum produces more oxidative stress.

A review of nationwide population study of organ transplantation in Taiwan

Solid organ transplantation has become the therapy of choice for patients with end-stage organ disease. The frequently transplanted organs in Taiwan include liver, kidney, heart, and lung, and the success rate has improved significantly worldwide for the past decades. However, organ recipients are known to be at a higher risk of post-transplant infections and de novo cancer due to immunosuppression and oncogenic viral infections. Organ recipients are known to be at a two- to fourfold increased risk of cancer and the risks are particularly high for malignancies caused by viral infections, including post-transplant lymphoproliferative disorders via Epstein-Barr virus, Kaposi sarcoma via Kaposi sarcoma herpesvirus, anogenital cancers via human papillomavirus, and hepatocellular carcinoma via hepatitis B and C virus. Population-based cohort studies may help better understand the pattern of infection and cancer risk in transplant recipients and clarify the role of the immune system, infection, and risk factors in the development of malignancy. Improvement of surgical techniques, advancement of immunosuppressant therapy in addition to early detection and prevention of infection, and regular surveillance of de novo cancer after transplantation have become the mainstay of successful organ transplantation.