Transoesophageal echo-Doppler vs. thermodilution cardiac output measurement during hepatic vascular exclusion in liver transplantation. Eur J Anaesthesiol. 2008;25:485-489. [PMID: 18298871 DOI: 10.1017/s0265021508003670]

Transoesophageal echocardiography during liver transplantation

Liver transplantation (LT) has become the standard of care for patients with end stage liver disease. The allocation of organs, which prioritizes the sickest patients, has made the management of liver transplant candidates more complex both as regards their comorbidities and their higher risk of perioperative complications. Patients undergoing LT frequently display considerable physiological changes during the procedures as a result of both the disease process and the surgery. Transoesophageal echocardiography (TEE), which visualizes dynamic cardiac function and overall contractility, has become essential for perioperative LT management and can optimize the anaesthetic management of these highly complex patients. Moreover, TEE can provide useful information on volume status and the adequacy of therapeutic interventions and can diagnose early intraoperative complications, such as the embolization of large vessels or development of pulmonary hypertension. In this review, directed at clinicians who manage TEE during LT, we show why the procedure merits a place in challenging anaesthetic environment and how it can provide essential information in the perioperative management of compromised patients undergoing this very complex surgical procedure.

Effect of perioperative terlipressin infusion on systemic, hepatic, and renal hemodynamics during living donor liver transplantation

BACKGROUND

End-stage liver disease is associated with marked hemodynamic disturbances that are further aggravated during liver transplantation. Terlipressin has been shown to be effective in the management of sepsis-induced hypotension and hepatorenal syndrome and recently has been tried as infusion during liver transplantation. This study assessed the effect of intraoperative and postoperative terlipressin infusion on systemic, hepatic, and renal hemodynamics during adult living donor liver transplantation.

METHODS

Eighty recipients were randomly allocated into control (C group; n=40) and terlipressin (TP group; n=40), in which, terlipressin infusion was started at the beginning of surgery at a dose of 3 μg kg(-1) h(-1) to be reduced to 1.5 μg kg(-1) h(-1) after reperfusion and continued for 3 postoperative days; vasoactive agents were used as appropriate in all patients. Systemic hemodynamics, hepatic and renal arterial resistive indices (HARI, RARI), and portal venous blood flow (PBF) were compared between both groups intraoperatively and for 5 postoperative days.

RESULTS

With terlipressin infusion, there were significant increases in both mean arterial pressure and systemic vascular resistance (P<.001), whereas heart rate and cardiac output decreased significantly (P<.001) throughout the study period compared with the C group. Vasoconstrictor drugs required during reperfusion were significantly lower in the TP group. There was a significant decrease in HARI, RARI, and portal venous blood flow in the TP group compared with the C group throughout the study period. There was no significant difference between both groups regarding liver function tests and serum lactate, whereas renal function tests were significantly better in the TP group.

CONCLUSION

Terlipressin infusion significantly decreased HARI, RARI, and portal vein flow and improved low systemic vascular resistance and mean arterial pressure. It helped to reduce intraoperative vasoactive support and might improve postoperative renal function.

The role of transesophageal echocardiography in the intraoperative period

The goal of hemodynamic monitoring and management during major surgery is to guarantee adequate organ perfusion, a major prerequisite for adequate tissue oxygenation and thus, end-organ function. Further, hemodynamic monitoring should serve to prevent, detect, and to effectively guide treatment of potentially life-threatening hemodynamic events, such as severe hypovolemia due to hemorrhage, or cardiac failure. The ideal monitoring device does not exist, but some conditions must be met: it should be easy and operator-independently to use; it should provide adequate, reproducible information in real time. In this review we discuss in particular the role of intraoperative use of transesophageal echocardiography (TOE). Although TOE has gained special relevance in cardiac surgery, its role in major non cardiac surgery is still to be determined. We particularly focus on its ability to provide measurements of cardiac output (CO), and its role to guide fluid therapy. Within the last decade, concepts oriented on optimizing stroke volume and cardiac output mainly by fluid administration and guided by continuous monitoring of cardiac output or so called functional parameters of cardiac preload gained particular attention. Although they are potentially linked to an increased amount of fluid infusion, recent data give evidence that such pre-emptive concepts of hemodynamic optimization result in a decrease in morbidity and mortality. As TOE allows a real time direct visualization of cardiac structures, other potentially important advantages of its use also outside the cardiac surgery operation room can be postulated, namely the ability to evaluate the anatomical and functional integrity of the left and the right heart chambers. Finally, a practical approach to TOE monitoring is presented, based on a local experience.

Use of transesophageal Doppler as a sole cardiac output monitor for reperfusion hemodynamic changes during living donor liver transplantation: An observational study

Aims:

To report the use of transesophageal Doppler (TED), a minimally invasive cardiac output (COP) monitor, before, during and after reperfusion and study its effect on anesthetic management during living donor liver transplantation (LDLT).

Setting and Design:

A prospective observational study.

Methods:

A total of 25 consecutive recipients with a MELD score between 15 and 20 were enrolled. Data were recorded at baseline (TB); anhepatic phase (TA); and post-reperfusion — 1, 5, 10 and 30 minutes. Fluid therapy was guided by corrected flow time (FTc) of the TED. Packed red blood cells (RBCs) were only given when hematocrit was less than 25%. Rotational thromboelastometry (ROTEM) and standard laboratory tests were used to guide component blood products requirements.

Results:

Post-reperfusion, the COP, Cardiac Index (CI) and stroke volume (SV) increased significantly at all points of measurements; this was associated with a significant decrease in systemic vascular resistance (SVR) (P ;< .05). Immediately post-reperfusion, for 5 minutes, mean arterial blood pressure (ABP) dropped significantly (P < .05), and 14 out of the 25 patients required boluses of epinephrine (10 μg) to restore the mean ABP; 3 of the 14 patients required norepinephrine infusion till the end of surgery. Central venous pressure (CVP) and urine output (UOP) at all measures were maintained adequately with FTc-guided fluid replacement. Eight out of the 25 patients required no blood transfusion, and 4 of the 8 patients required no catecholamine support.

Conclusion:

TED as a sole monitor for COP was able to present significant and reliable changes in the cardiovascular status of the recipients during reperfusion, which could help to guide fluid- and drug-supportive therapy in this population of patients. This preliminary study needs to be applied on a larger scale.

Optimizing cost-effectiveness in perioperative care for liver transplantation: a model for low- to medium-income countries

Although liver transplantation (LT) is a highly effective treatment, it has been considered too costly for publicly funded health systems in many countries with low to medium average incomes. However, with economic growth and improving results, some governments are reconsidering this position. Cost-effectiveness data for LT are limited, especially in perioperative care, and the techniques and costs vary widely between centers without overt differences in outcomes. Anesthesiologists working in new programs find it difficult to determine which modalities are essential, which are needed only in exceptional circumstances, and which may be omitted without effects on outcomes. We investigated key elements of preoperative evaluations, intraoperative management, and early postoperative care that might significantly affect costs in order to develop a best-value approach for new programs in resource-limited health systems. We identified all modalities of care commonly used in anesthesia and perioperative care for adult LT along with their costs. Those considered to be universally accepted as minimum requirements for safe care were excluded from the analysis, and so were those considered to be safe and low-cost, even when evidence of efficacy was lacking. The remaining items were, therefore, those with uncertain or context-restricted value and significant costs. A systematic review of the published evidence, practice surveys, and institutional guidelines was performed, and the evidence was graded and summarized. With respect to costs and benefits, each modality was then cited as strongly recommended, recommended or optional, or no recommendation was made because of insufficient evidence. Sixteen modalities, which included preoperative cardiovascular imaging, venovenous bypass, pulmonary artery catheterization, high-flow fluid warming devices, drug therapies for hemostasis, albumin, cell salvage, anesthetic drugs, personnel (staffing) requirements, and early extubation, were assessed. Only high-flow fluid warming was strongly recommended. The recommended modalities included preoperative echocardiography, cell salvage, tranexamic acid and early extubation. Six others were rated optional, and there was insufficient evidence for 5 modalities. We conclude that some costly techniques and treatments can be omitted without adverse effects on outcomes.

Cardiac output monitoring: is there a gold standard and how do the newer technologies compare?

As a principal determinant of oxygen delivery and of blood pressure, cardiac output (CO) represents an important hemodynamic variable. Its accurate measurement, therefore, is important to the clinician caring for critically ill patients in a variety of care environments. Though the first clinical measurement of CO occurred 70 years ago, it was the introduction of the pulmonary artery catheter (PAC) with thermodilution-based determination of CO in the 1970s that set the stage for practical and widespread clinical measurement of CO. Although the usefulness and accuracy of this technique have justified its consideration as a "practical" gold standard in CO measurement, its drawbacks have driven the search for newer, less invasive measurement techniques. The last decade has seen the introduction of several such devices into the clinical arena. This article will serve to give a brief review of the history of CO measurement, to provide a discussion of the measurement of accuracy as it relates to CO measurement, and to discuss some of the newer methods and devices for CO measurement and how they have fared against a "practical" gold standard.

Techniques of cardiac output measurement during liver transplantation: arterial pulse wave versus thermodilution

In this study, we compared continuous cardiac output (CO) obtained from the femoral arterial pressure by simulation of an aortic input impedance model [model-simulated cardiac output (MCO)] to thermodilution cardiac output (TDCO) determined by bolus injection during liver transplantation. Both variables were measured in 39 adult patients (13 females) every 10th minute during liver transplant surgery. Paired measurements were compared during the 4 phases of surgery-dissection, anhepatic phase, early reperfusion (the first 15 minutes after reperfusion), and late reperfusion (15-60 minutes after reperfusion)-without the detection of any significant difference between the 2 estimates of CO. TDCO ranged from 2.3 to 17.2 L/minute, and the bias (the mean difference between MCO and TDCO) prior to calibration was -0.4 +/- 1.6 L/minute (mean +/- standard deviation; 1309 paired measurements; 95% limits of agreement: -3.4 to 2.6 L/minute). After calibration of the first determined MCO by the simultaneously determined TDCO, the bias was 0.1 +/- 1.5 L/minute, with 57% (n = 744) of the comparisons being less than 1 L/minute and 35% (n = 453) being less than 0.5 L/minute; this was independent of the level of CO, and the mutual correlation coefficient was 0.812 (P < 0.001). This study indicates that during liver transplantation surgery, MCO reflects TDCO throughout the operation. Thus, for CO, this less invasive method appears to provide a reliable uninterrupted measurement during orthotopic liver transplantation.