Pulse Contour Cardiac Output System Use in Pediatric Orthotopic Liver Transplantation: Preliminary Report of Nine Patients

PERIOPERATIVE TECHNIQUES

Pulse Contour Cardiac Output System Use in Pediatric Orthotopic Liver Transplantation: Preliminary Report of Nine Patients A. Torgay, A. Pirat, E. Akpek, P. Zeyneloglu, G. Arslan, and M. Haberal ABSTRACT Anesthetic management of orthotopic liver transplantation (OLT) in pediatric patients is challenging in terms of intraoperative bleeding, fluid management, and hemodynamic monitoring. The pulse contour cardiac output (PiCCO) system, a relatively new device based on the single-indicator transaortic thermodilution technique, may be useful for intraoperative hemodynamic monitoring in pediatric patients. This is a preliminary report of PiCCO use in nine children (aged 9.8 ⫾ 4.7 years) undergoing OLT. Hemodynamic volumetric parameters monitored by the PiCCO system were mean arterial pressure (MAP), cardiac index (CI), intrathoracic blood volume index (ITBVI), extravascular lung water index (EVLWI), systemic vascular resistance index (SVRI), and stroke volume variability (SVV). All parameters were recorded at anesthesia induction (T0), at the end of the anhepatic phase (Tanhepatic), and at the end of operation (Tend). The PiCCO system revealed similar MAP, CI, EVLWI, SVV, and SVRI values at all measurement intervals. Despite similar central venous pressure measurements, ITBVI values indicated significantly lower values at Tanhepatic than at T0 (627 ⫾ 160 mL/m2 and 751 ⫾ 151 mL/m2, respectively, P ⫽ .013). There were no PiCCO catheter-related complications in any patient. These findings demonstrate that the PiCCO system is a safe, continuous, multiparameter invasive monitoring device for use in pediatric patients undergoing OLT. This system may provide valuable data during pediatric OLT and appears to be a promising monitoring tool in these patients.

C

ARDIAC OUTPUT (CO) and invasive hemodynamic measurements are used almost routinely during adult orthotopic liver transplantation (OLT), because massive transfusion of blood products is frequently required, and hemodynamic deterioration is common.1,2 Traditionally, a pulmonary artery catheter and a bolus thermodilution technique have been used for invasive hemodynamic monitoring during OLT. Recently, several investigators have reported the successful use of the aortic transpulmonary technique and continuous measurement of CO from the arterial pulse contour analysis (PiCCO system) during OLT in adults.3–5 The PiCCO system is less invasive than the traditional system and provides valuable data regarding the patient’s preload, afterload, myocardial contractility, and extravascular lung water index (EVLWI).

OLT may be associated with similar intraoperative hemodynamic problems in pediatric patients; however, lack of properly sized pulmonary artery catheters and technical difficulties limit extensive use of this monitoring tool in children.6 Although the PiCCO system has been designed for both adult and pediatric patients, its use for intraoperative hemodynamic monitoring in pediatric patients undergoing OLT has not yet been reported. This preliminary From the Baskent University Faculty of Medicine, Departments of Anesthesiology (A.T., A.P., E.A., P.Z., G.A.) and General Surgery (M.H.), Ankara, Turkey. Address reprint requests to Arash Pirat, Baskent University Hospital, 10. sok. No:45 Bahçelievler, Ankara, 06490 Turkey. E-mail: [email protected]

0041-1345/05/$–see front matter doi:10.1016/j.transproceed.2005.07.020

© 2005 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710

3168

Transplantation Proceedings, 37, 3168 –3170 (2005)

PULSE CONTOUR CARDIAC OUTPUT SYSTEM Table 1. Patients’ Demographics and Perioperative Data Age (y) Weight (kg) Sex (M/F) Preoperative Hemoglobin (g/dL) Platelet count/mm3 Alanine aminotransferase (U/L) Total bilirubin (mg/dL) Albumin (g/dL) Creatinine (mg/dL) International normalized ratio Duration of surgery (h) Length of stay in the ICU Intraoperative Fluids (mL/kg) Transfusions (mL/kg) Urine output (mL/kg/h)

9.8 ⫾ 4.7 (2–17) 32.4 ⫾ 14.2 (10–50) 5/4 9.4 ⫾ 1.0 121,000 ⫾ 46,000 483 ⫾ 1172 (13–3605) 13.7 ⫾ 12.8 (0.4–38.6) 3.53 ⫾ 0.41 0.50 ⫾ 0.29 2.31 ⫾ 1.68 8.3 ⫾ 2.0 43.2 ⫾ 23.0 149 ⫾ 24 (102–173) 46 ⫾ 13 (29–69) 1.98 ⫾ 1.00 (0.69–3.85)

report describes PiCCO use in nine pediatric patients undergoing OLT. PATIENTS AND METHODS The records of nine children who had undergone OLT between June 2003 and June 2004 included preoperative physical characteristics and laboratory values. Anesthesia was induced with a combination of sodium thiopental (2 to 4 mg/kg) and fentanyl (3 to 5 ␮g/kg). Vecuronium was given to facilitate endotracheal intubation (0.1 mg/kg) and maintain paralysis during surgery (1 to 2 ␮g/kg/min). Anesthesia maintenance was achieved with an isoflurane/air/O2 mixture and a remifentanil infusion (0.1 to 0.2 ␮g/kg/min). Intraoperative monitoring was performed using electrocardiography, pulse oximetry, capnography, nasopharyngeal temperature, and invasive arterial (radial artery) and central venous (internal jugular or subclavian vein) pressure measurements. After anesthesia induction, a thermodilution femoral artery catheter (3-French, PV2013L07, if ⱕ20 kg; and 4-French, PV2014L08, if ⬎20 kg) was inserted into the left femoral artery in each patient. This catheter was connected to a PiCCO system (version 5.2.2, Pulsion Medical Systems AG, Munich, Germany) to monitor mean arterial pressure, systemic vascular resistance index (normal values ⫽ 1200 to 2000 dynes·sec·m2·cm⫺5), bolus thermodilution cardiac index (CI; normal values ⫽ 3.5 to 5.0 L·min⫺1·m⫺2), pulse contour continuous cardiac index (normal values ⫽ 3.5 to 5.0 L·min⫺1·m⫺2), intrathoracic blood volume index (ITBVI; normal values ⫽ 850 to 1000 mL/m2), EVLWI (normal values ⫽ 3.0 to 7.0 mL/kg), and stroke volume variability (SVV,

3169 normal values ⱕ10%). These measurements were performed by injecting 5 to 10 mL (5 mL if ⱕ20 kg and 10 mL if ⬎20 kg) of cold saline solution, at a temperature of less than 8 °C via the distal port of the central venous catheter. All PiCCO parameters were recorded at three time intervals: after anesthesia induction (T0), at the end of the anhepatic phase (Tanhepatic), and at the end of the operation (Tend). Colloids and crystalloids were administered to maintain adequate urine output (⬎0.5 mL/h) and hold central venous pressure at 8 to 12 mm Hg, and ITBVI, CI, and SVV within normal ranges. Intraoperative blood loss was compensated by transfusing packed red blood cells or whole blood to maintain an hematocrit above 30%. Fresh frozen plasma (FFP) and platelets were administered according to laboratory findings. Platelets were given when the count fell below 50 ⫻ 109/L, and FFP when the prothrombin time was longer than 20 seconds. Venovenous bypass, aprotinin, and tranexamic acid were not used in any patient. The procedures were performed by the same surgeons using a piggyback technique. All data were analyzed using SPSS software (Statistical Package for the Social Sciences, version 11.0, SSPS Inc, Chicago, Ill, USA). Unless otherwise stated, data are expressed as mean values ⫾ standard deviations (mean ⫾ SD). The range is indicated between parentheses when necessary. A repeated measures analysis of variance was used to assess differences among the baseline and other time points of measurement. The significance of differences between two time points of measurement was analyzed by a paired t test with Bonferroni correction. A P value less than .05 was considered to be statistically significant.

RESULTS

The patients’ physical characteristics and their perioperative data are given in Table 1. The patients’ hemodynamic measurements and PiCCO parameters were similar at all assessment intervals except for the ITBVI (Table 2). The mean baseline ITBVI value significantly decreased during the anhepatic phase (Table 2). There were no complications related to femoral artery catheterization. Six patients were extubated at the end of the surgery. The other three, who all had preoperative hepatic encephalopathy, were extubated at 14, 29, and 32 hours after surgery. All patients were discharged from the ICU uneventfully. DISCUSSION

Accurate hemodynamic monitoring and adequate fluid replacement during OLT are two of the most challenging

Table 2. Patients’ Hemodynamic Measurements and PiCCO Parameters at Baseline (T0), End of Anhepatic Phase (Tanhepatic), and End of the Surgery (Tend)

Mean arterial pressure (mm Hg) Central venous pressure (mm Hg) Cardiac index (L·min⫺1·m⫺2) Intrathoracic blood volume index (mL/m2) Extravascular lung water index (mL/kg) Stroke volume variability (%) Systemic vascular resistance index (dyn·s·m2·cm⫺5) *P ⫽ 0.013 compared with T-anhepatic value.

T0

Tanhepatic

Tend

71.3 ⫾ 11.3 11.9 ⫾ 3.3 5.93 ⫾ 1.64 751 ⫾ 151* 8.1 ⫾ 5.3 11.4 ⫾ 4.3 1197 ⫾ 430

68.2 ⫾ 20.0 10.1 ⫾ 2.9 4.92 ⫾ 1.93 627 ⫾ 160 8.5 ⫾ 3.2 12.8 ⫾ 4.5 1387 ⫾ 458

74.3 ⫾ 15.1 10.2 ⫾ 1.5 6.29 ⫾ 1.14 692 ⫾ 143 8.1 ⫾ 2.1 12.8 ⫾ 9.8 1120 ⫾ 730

3170

tasks for anesthesiologists.3–5 Inadequate cardiac filling may lead to suboptimal tissue perfusion and multiple organ failure. On the other hand, excessive cardiac filling may in turn result in pulmonary edema and hypoxemia.5 Since the introduction of the pulmonary artery catheter by Swan and Ganz in 1970, the pulmonary artery thermodilution technique has become the gold standard for measuring CO.5 Conventional methods of CO monitoring using pulmonary artery catheters usually measure this parameter intermittently; however, a continuous measurement is preferable. Another important problem regarding the transpulmonary thermodilution CO measurement is that this technique requires pulmonary artery catheterization, which may not be feasible in children because of their small size or technical difficulties. Another important issue regarding this technique is the risk of pulmonary artery catheter, which has been recently discussed.7 The PiCCO system avoids the use of a pulmonary artery catheter; it requires only central venous and femoral artery catheters. Because central and arterial catheters are routinely used during major surgical procedures such as OLT, PiCCO provides valuable information regarding the patient’s hemodynamic status with no additional invasive procedures. After an initial bolus transaortic thermodilution CO measurement, the PiCCO system also provides continuous data regarding CO changes using the pulse contour CO analysis technique. To our knowledge, this is the first study that demonstrates the use of the PiCCO system in pediatric OLT. Previous studies have shown that the PiCCO system CI measurements agree with CI measurements that are performed using a pulmonary artery catheter in adult OLT.1 Another important advantage of the transaortic thermodilution technique over the transpulmonary thermodilution technique is that it measures both right and left ventricular output and it is not affected by respiratory cyclic variations in pulmonary blood flow.5 Use of the PiCCO system in pediatric OLT deserves special interest because it eliminates the need for a pulmonary artery catheter, which may be problematic in this group of patients. Assessment of cardiac preload is of primary importance in guiding volume therapy and vasoactive drug administration to optimize organ perfusion and avoid fluid overload that can be dangerous and increase lung edema in children during OLT. Because traditional markers of preload, CVP, and PCWP are indirect parameters of cardiac preload and depend on many factors other than intravascular volume, direct measurement of blood volume that constitutes preload would be desirable. Studies have shown that PCWP is influenced by so many factors other than cardiac filling that it is not a reliable estimate of cardiac filling during several situations in clinical practice. Indicator dilution-derived ITBVI has been suggested to be a sensitive indicator of

TORGAY, PIRAT, AKPEK ET AL

cardiac preload, because volume changes preferentially alter the volume in the intrathoracic compartment, which serves as the primary reservoir for the left ventricle. Studies have indicated that there is a better correlation between CI and volume measurements than the correlation with pressure preload parameters.3–5,8 We did not observe any complications related to the use of the PiCCO system in our patients, and the femoral artery catheter was easily inserted in all cases. In addition, this technique was found to be convenient and easy to use. However, the system has its limitations. Aortic aneurysms, intra-aortic balloon pumps, as well as peripherally inserted catheters may overestimate the volumes. Another important problem regarding the use of the PiCCO system is that intracardiac shunts may limit its use. In conclusion, these preliminary results suggest that the PiCCO system is a safe and convenient hemodynamic monitoring tool for use during pediatric OLT. This technique may provide invaluable data regarding a patient’s intravascular volume status, afterload, CO, and myocardial contractility during OLT. However, whether these results will translate into improved patient management during pediatric OLT remains to be confirmed in a larger case series.

REFERENCES 1. Schroeder RA, Collins BH, Tuttle-Newhall E, et al: Intraoperative fluid management during orthotopic liver transplantation. J Cardiothorac Vasc Anesth 18:438, 2004 2. Pirat A, Sargin D, Torgay A, et al: Identification of preoperative predictors of intraoperative blood transfusion requirement in orthotopic liver transplantation. Transplant Proc 34:2153, 2002 3. Della Rocca G, Costa MG, Pompei L, et al: Continuous and intermittent cardiac output measurement: pulmonary artery catheter versus aortic transpulmonary technique. Br J Anaesth 88:350, 2002 4. Della Rocca G, Costa MG, Coccia C, et al: Preload and haemodynamic assessment during liver transplantation: a comparison between the pulmonary artery catheter and transpulmonary indicator dilution techniques. Eur J Anaesthesiol 19:868, 2002 5. Diaz S, Perez-Pena J, Sanz J, et al: Haemodynamic monitoring and liver function evaluation by pulsion cold system Z-201 (PCS) during orthotopic liver transplantation. Clin Transplant 17:47, 2003 6. Ruperez M, Lopez-Herce J, Garcia C, et al: Comparison between cardiac output measured by the pulmonary arterial thermodilution technique and that measured by the femoral arterial thermodilution technique in a pediatric animal model. Pediatr Cardiol 25:119, 2004 7. Rhodes A, Cusack RJ, Newman PJ, et al: A randomised, controlled trial of the pulmonary artery catheter in critically ill patients. Intensive Care Med 28:256, 2002 8. Wiesenack C, Prasser C, Keyl C, et al: Assessment of intrathoracic blood volume as an indicator of cardiac preload: single transpulmonary thermodilution technique versus assessment of pressure preload parameters derived from a pulmonary artery catheter. J Cardiothorac Vasc Anesth 15:584, 2001