Uncalibrated continuous cardiac output measurement in liver transplant patients: LiDCOrapid™ system versus pulmonary artery catheter.

OBJECTIVE: The aim of the study was to assess the level of agreement between continuous cardiac output estimated by uncalibrated pulse-power analysis (PulseCOLiR) and intermittent (ICO) and continuous cardiac output (CCO) obtained using a pulmonary artery catheter (PAC). DESIGN: Prospective cohort study. SETTING: University hospital intensive care unit. PARTICIPANTS: Twenty patients after liver transplantation. INTERVENTION: Pulmonary artery catheters were placed in all patients, and ICO and CCO were determined using thermodilution. PulseCOLiR measurements were made using a LiDCOrapid(TM) (LiDCO Ltd, Cambridge, UK). MEASUREMENTS AND MAIN RESULTS: ICO data were determined after intensive care unit admission and every 8 hours until the 48th postoperative hour. CCO and PulseCOLiR measurements were recorded simultaneously at these same time intervals as well as hourly. For the 8-hour data set (140 data pairs), the mean bias and percentage errors (PE) were, respectively,-0.10 L/min and 39.2% for ICO versus PulseCOLiR and 0.79 L/min and 34.6% for CCO versus PulseCOLiR. For the hourly comparison of CCO versus PulseCOLiR (980 data pairs), the bias was 0.75 L/min and the PE 37%. To assess the ability to measure change, a 4-quadrant plot was produced for each pair of methods. The performance of PulseCOLiR was moderate in detecting changes in ICO. CONCLUSIONS: In conclusion, the uncalibrated PulseCOLir method should not be used as a substitute for the thermodilution technique for the monitoring of cardiac output in liver transplant patients.

Effects of catecholamines on microcirculation during general inhalation anesthesia.

OBJECTIVE: The aim of this study was to investigate the effects of clinical dosages of norepinephrine and dobutamine on sublingual microcirculation during general anesthesia with sevoflurane in minor surgical procedures. DESIGN: This prospective study was performed on patients scheduled for breast cancer surgery. SETTING: Tertiary care university hospital. PARTICIPANTS: Twenty patients undergoing elective surgery. INTERVENTIONS: Patients received a continuous infusion of norepinephrine (0.1 µg/kg/min) and afterwards, following a 15-minute interval, a continuous infusion of dobutamine (5 µg/kg/min). Prior to and at the end of each drug infusion period, hemodynamic parameters were measured using an esophageal Doppler probe (ED), and 5 sidestream darkfield (SDF) sublingual microcirculation video recordings were taken. MEASUREMENTS AND MAIN RESULTS: No significant changes to total vessel density (TVD)(mm/mm(2)), perfused vessel density (PVD) (mm/mm(2)), proportion of perfused vessels (PPV) (percentage), or microvascular flow index (MFI) (arbitrary units) were measured at the end of each drug infusion period versus pre-infusion data and no differences were observed between the effects of norepinephrine versus dobutamine. Mean arterial pressure (APm) (mmHg) was significantly greater following both norepinephrine and dobutamine infusions compared to pre-infusion values, while peak velocity (PV) (cm/sec) and the stroke volume index (SVI) (mL/m(2)) only showed a significant increase following the dobutamine infusion. No change in corrected flow time (FTc) (msec) was observed. CONCLUSIONS: During general anesthesia with sevoflurane, the infusion of clinical dosages of norepinephrine and dobutamine did not alter sublingual perfusion, although the expected systemic hemodynamic alterations were induced.

Prognostic power of pre- and postoperative B-type natriuretic peptide levels in patients undergoing abdominal aortic surgery.

OBJECTIVES: The first aim of the present study was to evaluate the pre- and postoperative B-type natriuretic peptide (BNP) levels in patients undergoing surgery for repair of an infrarenal abdominal aortic aneurysm (AAA) and analyze their power as a predictor of in-hospital cardiac events. The second aim was to evaluate the association among pre- and postoperative BNP levels, postoperative patient complications, and length of hospital stay. DESIGN: Prospective observational study. SETTING: A university hospital. PARTICIPANTS: Forty-five patients undergoing elective surgery for an abdominal aortic aneurysm. INTERVENTIONS: The plasma BNP level was assessed just before surgery and then on postoperative day 1. Cardiac troponin I levels were measured postoperatively on arrival to the intensive care unit (time 0) and then 12, 48, and 72 hours later. MEASUREMENTS AND MAIN RESULTS: The preoperative BNP concentration in patients who developed an acute myocardial infarction was 209 (IQR 84-346) pg/mL compared with 74 (IQR 28-142) pg/mL in those who did not. The difference between groups was statistically significant (p = 0.04). The Spearman correlation showed that postoperative BNP levels correlated significantly with preoperative BNP levels (r = 0.73, p = 0.0001), length of hospital stay (r = 0.35, p = 0.04), and troponin I concentration at 0 hour (r = 0.42, p = 0.02), 12 hours (r = 0.51, p = 0.0052), and 48 hours (r = 0.40, p = 0.033). In contrast, preoperative BNP levels correlated with troponin I at only 12 hours (r = 0.34, p = 0.02). Postoperative BNP levels were influenced significantly by transfusions (p = 0.035) and cross-clamping times (p = 0.038). CONCLUSIONS: The present results confirm the high negative predictive value of preoperative BNP levels; and postoperative BNP levels showed a better correlation with postoperative troponin levels, blood transfusion, and postoperative cardiac events.

The dos and do knots of central venous catheterization.

Central venous catheterization plays an important role in patients with end-stage renal disease undergoing hemodialysis. Placement of a right subclavian hemodialysis catheter was complicated by looping and entrapment of the guidewire. Computed tomographic and three-dimensional scans were essential in locating and determining that the guidewire was outside the vessel.

Lack of a correlation between portal vein flow and pressure: toward a shared interpretation of hemodynamic stress governing inflow modulation in liver transplantation.

The portal vein flow (PVF), portal vein pressure (PVP), and hepatic venous pressure gradient (HVPG) were prospectively assessed to explore their relationships and to better define hyperflow and portal hypertension (PHT) during liver transplantation (LT). Eighty-one LT procedures were analyzed. No correlation between PVF and PVP was observed. Increases in the central venous pressure (CVP) were transmitted to the PVP (58%, range = 25%-91%, P = 0.001). Severe PHT (HVPG ≥ 15 mm Hg) showed a significant reciprocal association with high PVF (P = 0.023) and lower graft survival (P = 0.04). According to this initial experience, an HVPG value ≥ 15 mm Hg is a promising tool for the evaluation of hemodynamic stress potentially influencing outcomes. An algorithm for graft inflow modulation based on flows, gradients, and systemic hemodynamics is provided. In conclusion, the evaluation of PHT severity with PVP could be delusive because of the influence of CVP. PVF and PVP do not correlate and should not be used individually to assess hyperflow and PHT during LT.

Uncalibrated arterial pulse cardiac output measurements in patients with moderately abnormal left ventricular function.

OBJECTIVE: The aim of the study was to evaluate the accuracy and precision of the Vigileo/FloTrac system (Edwards Lifesciences, Irvine, CA) when compared with the intermittent cardiac output and continuous cardiac output measurements obtained from pulmonary arterial catheters in patients with moderately abnormal left ventricular function undergoing elective coronary artery bypass graft surgery. DESIGN: A prospective, observational study. SETTING: Tertiary university hospital. PARTICIPANTS: Twenty patients with moderately abnormal left ventricular function undergoing coronary artery bypass graft surgery were enrolled. MEASUREMENTS AND RESULTS: Data were collected before the induction of anesthesia (T1), after the induction of anesthesia (T2), before cardiopulmonary bypass with an open chest (T3), after cardiopulmonary bypass (T4), after sternal closure (T5), on intensive care unit admission (T6), and at 6 hours (T7) and 12 hours after surgery (T8). A total of 360 data measurements were collected; the mean bias between intermittent cardiac output (ICO) and arterial pressure cardiac output (APCO) was -0.50 ± 1.72 L/min, and the percentage error (PE) was 37.00%. The mean difference between CCO and APCO was -0.06 ± 1.84 L/min, and the PE was 37.80%. The correlation between ΔICO and ΔAPCO was r = 0.7; the correlation between ΔCCO and ΔAPCO was r = 0.73. In the intraoperative period, the mean bias between ICO and APCO was -0.41 ± 1.75 L/min, and the PE was 40.87%. The mean difference between CCO and APCO was -0.18 ± 1.90 L/min, and the PE was 41.48%. In the postoperative period, the mean bias between ICO and APCO was -0.56 ± 1.70 L/min, and the PE was 34.43%. The mean difference between CCO and APCO was -0.36 ± 1.76 L/min, and the PE was 34.87%. CONCLUSIONS: In cardiac surgical patients with moderately abnormal left ventricular function, the Vigileo/FloTrac 2nd generation software sensor device showed mild intraoperative and postoperative agreement when compared with a pulmonary arterial catheter.

Intraoperative hemodynamic monitoring during organ transplantation: what is new?

PURPOSE OF REVIEW: To highlight the recent developments in hemodynamic monitoring during liver and lung transplantation. RECENT FINDINGS: Even though a consensus on intraoperative hemodynamic monitoring is still lacking, the most frequently monitoring tool used is the pulmonary artery catheter (PAC). The filling pressures are widely accepted as not being able to accurately define cardiac preload. On the contrary, the use of transesophageal echocardiography (TEE), although it is operator dependent and requires a prolonged training, is increasing during the intraoperative period to directly evaluate the cardiovascular function. New frontiers have been opened by the transpulmonary thermodilution: intrathoracic blood volume has been shown to have a better correlation with preload than the filling pressures. The advanced modified PAC permits evaluation of the right heart function and preload. Recently, right ventricular end diastolic volume has been shown to correlate better with preload than the filling pressures and also the left ventricular end diastolic area. SUMMARY: The PAC still represents the most used intraoperative hemodynamic monitoring technique. TEE is increasing in popularity. Recent studies demonstrate that volumetric monitoring conducted with transpulmonary thermodilution and advanced volumetric PAC give good definition of preload and should be implemented in clinical practice.

Continuous right ventricular end-diastolic volume in comparison with left ventricular end-diastolic area.

BACKGROUND AND OBJECTIVE: Intraoperative management of patients with end-stage liver disease undergoing liver transplantation requires fluid administration to increase cardiac output and oxygen delivery to the tissues. Filling pressures have been widely shown to correlate poorly with changes in cardiac output in the critically ill patient. Continuous right ventricular end-diastolic volume index (cRVEDVI) and left ventricular end-diastolic area index (LVEDAI) monitoring have been increasingly used for preload assessment. The aim of this study was to compare cRVEDVI, LVEDAI, central venous pressure and pulmonary artery occlusion pressure with respect to stroke volume index (SVI) during liver transplantation. METHODS: Measurements were made in 20 patients at four predefined steps during liver transplantation. Univariate and multivariate panel-data fixed effect regression models (across phases of the surgical procedure) were fitted to assess associations between SVI and cRVEDVI, pulmonary artery occlusion pressure, central venous pressure and LVEDAI after adjusting for ejection fraction (categorized as 40). RESULTS: SVI was associated with continuous right ventricular ejection fraction. The model showing the best fit to the data was that including cRVEDVI: even after adjusting for continuous right ventricular ejection fraction and phase, the regression coefficient of cRVEDVI in predicting SVI was statistically significant and indicated an increase in SVI of 0.21 ml m(-2) for each increase of 1 ml m(-2). At the multivariate analysis, an increase in LVEDAI of 1 cm m(-2) led to an increase in SVI of 1.47 ml m(-2) (P = 0.054). CONCLUSION: cRVEDVI and LVEDAI gave a better reflection of preload than filling pressure, even if only cRVEDVI reached statistical significance.

Arterial pulse cardiac output agreement with thermodilution in patients in hyperdynamic conditions.

OBJECTIVE: This study aimed to compare continuous cardiac output (CCO) obtained using the arterial pulse wave (APCO) measurement with a simultaneous measurement of the intermittent cardiac output (ICO) and CCO obtained with a pulmonary artery catheter (PAC) in liver transplant patients. DESIGN: A prospective, single-center evaluation. SETTING: A university hospital intensive care unit. PATIENTS: Eighteen patients after liver transplantation. INTERVENTIONS: Pulmonary artery catheters were placed in all patients, and ICO and CCO were determined using thermodilution. APCO measurements were made with the Vigileo System (Edwards Lifesciences, Irvine, CA). MEASUREMENTS AND MAIN RESULTS: The authors obtained 126 data pairs of ICO and APCO and 864 pairs of CCO and APCO. ICO data were collected after intensive care unit admission and every 8 hours until the 48th postoperative hour. CCO and APCO data were collected every hour from admission until the 48th postoperative hour. Bias and precision were 0.95 +/- 1.41 L/min for ICO versus APCO and 1.29 +/- 1.28 L/min for CCO and APCO. Bias and precision for cardiac output (CO) data pairs less than 8 L/min were 0.32 +/- 1.14 L/min between ICO and APCO and 0.71 +/- 0.98 L/min between CCO and APCO. For CO data pairs higher than 8 L/min, bias and precision were 1.79 +/- 1.54 L/min between ICO and APCO and 2.25 +/- 1.14 L/min between CCO and APCO. CONCLUSIONS: APCO enables the assessment of CO with clinically acceptable bias and precision. At higher CO levels, APCO underestimates PAC measurements and it is not as reliable as thermodilution in hyperdynamic liver transplant patients.

Continuous right ventricular end diastolic volume and right ventricular ejection fraction during liver transplantation: a multicenter study.

Cardiac preload is traditionally considered to be represented by its filling pressures, but more recently, estimations of end diastolic volume of the left or right ventricle have been shown to better reflect preload. One method of determining volumes is the evaluation of the continuous right ventricular end diastolic volume index (cRVEDVI) on the basis of the cardiac output thermodilution technique. Because preload and myocardial contractility are the main factors determining cardiac output during liver transplantation (LTx), accurate determination of preload is important. Thus, monitoring of cRVEDVI and cRVEF should help with fluid management and with the assessment of the need for inotropic and vasoactive agents. In this multicenter study, we looked for possible relationships between the stroke volume index (SVI) and cRVEDVI, cRVEF, and filling pressures at 4 predefined steps in 244 patients undergoing LTx. Univariate and multivariate autoregression models (across phases of the surgical procedure) were fitted to assess the possible association between SVI and cRVEDVI, pulmonary artery occlusion pressure (PAOP), and central venous pressure (CVP) after adjustment for cRVEF (categorized as < or =30, 31-40, and >40%). SVI was strongly associated with both cRVEDVI and cRVEF. The model showing the best fit to the data was that including cRVEDVI. Even after adjustment for cRVEF, there was a statistically significant (P < 0.05) relationship between SVI and cRVEDVI with a regression coefficient (slope of the regression line) of 0.25; this meant that an increase in cRVEDVI of 1 mL m(-2) resulted in an increase in SVI of 0.25 mL m(-2). The correlations between SVI and CVP and PAOP were less strong. We conclude that cRVEDVI reflected preload better than CVP and PAOP.

Continuous and intermittent cardiac output measurement in hyperdynamic conditions: pulmonary artery catheter vs. lithium dilution technique.

OBJECTIVE: This study aimed to assess the level of agreement of both intermittent cardiac output monitoring by the lithium dilution technique (CO(Li)) and continuous cardiac output monitoring (PulseCO(Li)) using the arterial pressure waveform with intermittent thermodilution using a pulmonary artery catheter (CO(PAC)). DESIGN: Prospective, single-center evaluation. SETTING: University Hospital Intensive Care Unit. PATIENTS: Patients (n=23) receiving liver transplantation. INTERVENTION: Pulmonary artery catheters were placed in all patients and CO(PAC) was determined using thermodilution. CO(Li) and PulseCO(Li) measurements were made using the LiDCO system. MEASUREMENTS AND MAIN RESULTS: Data were collected after intensive care unit admission and every 8h until the 48th hour. A total of 151 CO(PAC), CO(Li) and PulseCO(Li) measurements were analysed. Bias and 95% limit of agreement were 0.11lmin(-1) and -1.84 to + 2.05 lmin(-1) for CO(PAC) vs. CO(Li) (r=0.88) resulting in an overall percentage error of 15.6%. Bias and 95% limit of agreement for CO(PAC) vs. PulseCO(Li) were 0.29 lmin(-1) and -1.87 to + 2.46 lmin(-1) (r=0.85) with a percentage error of 16.8%. Subgroup analysis revealed a percentage error of 15.7% for CO(PAC) vs. CO(Li) and 15.1% for CO(PAC) vs. PulseCO(Li) for data pairs less than 8 lmin(-1), and percentage errors of 15.5% and 18.5% respectively for data pairs higher than 8 lmin(-1). CONCLUSION: In patients with hyperdynamic circulation, intermittent and continuous CO values determined using the LiDCO system showed good agreement with those obtained by intermittent pulmonary artery thermodilution.

How to measure and interpret volumetric measures of preload.

PURPOSE OF REVIEW: To update the situation over the past few years on the clinical application of volumetric measures of preload in critically ill patients. RECENT FINDINGS: Cardiac filling pressures monitoring is unreliable for assessing cardiac preload in mechanically ventilated critically ill patients. The transpulmonary dilution indicator technique was shown to better identify preload than pulmonary arterial catheterization. Measuring static preload index as intrathoracic blood volume or global end diastolic volume provides a good preload index, either in experimental or in different clinical settings. SUMMARY: Volumetric measures of preload are good preload indexes. These data are to be interpreted together with the clinical patient's condition, conventional hemodynamic data and the course of illness in critically ill patients. In order to evaluate whether the application of a predefined therapy algorithm based on volumetric monitoring can improve patients' outcome, more studies are needed.

Cardiac output monitoring: aortic transpulmonary thermodilution and pulse contour analysis agree with standard thermodilution methods in patients undergoing lung transplantation.

PURPOSE: The PiCCO System is a relatively new device allowing intermittent cardiac output monitoring by aortic transpulmonary thermodilution technique (Aorta intermittent) and continuous cardiac output monitoring by pulse contour analysis (Aorta continuous). The objective of this study was to assess the level of agreement of Aorta intermittent and Aorta continuous with intermittent (PA intermittent) and continuous cardiac output (PA continuous) measured through a special pulmonary artery catheter (Vigilance System SvO(2)/CCO Monitor) in patients undergoing single- or double-lung transplantation. METHODS: Measurements were obtained in 58 patients: at four time points in patients undergoing single-lung transplantation and at six time points in those undergoing double-lung transplantation. Bland and Altman and correlation analyses were used for statistical evaluation. RESULTS: We found close agreement between the techniques. Mean bias between Aorta intermittent and PA intermittent and between Aorta continuous and PA continuous was 0.18 L x min(-1) (2SD of differences between methods = 1.59 L x min(-1)) and -0.07 L x min(-1) (2SD of differences between methods = 1.46 L x min(-1)) respectively. Mean bias between PA continuous and PA intermittent and Aorta continuous and PA intermittent was 0.15 L x min(-1) (2SD of differences between methods = 1.39 L x min(-1)) and 0.08 L x min(-1) (2SD of differences between methods = 1.43 L x min(-1)). CONCLUSION: Measurements with the aortic transpulmonary thermodilution technique give continuous and intermittent values that agree with the pulmonary thermodilution method which is still the current clinical standard.

Preload indexes in thoracic anesthesia.

PURPOSE OF THE REVIEW: An adequate cardiac preload is essential in the treatment of critically ill patients. During anesthesia for thoracic surgery, volume and vasoactive therapy to optimize cardiac output, oxygen delivery (tissue perfusion) and to avoid pulmonary edema is a central therapeutic aspect. Cardiac preload has been estimated with different techniques in clinical practice, even though studies performed on thoracic anesthesia are lacking. RECENT FINDINGS: We analyze the conventional pulmonary artery catheter, transesophageal echocardiography and the transpulmonary indicator dilution technique as preload monitoring devices with their indications and limits in thoracic anesthesia. SUMMARY: The pulmonary artery catheter is confirmed as a fundamental device particularly in patients with pulmonary hypertension. For transesophageal echocardiography monitoring, the dependency on operator experience, the low repeatability and the high costs limit its interpretation and diffusion in clinical practice. During lung transplantation, Swan Ganz catheter monitoring is recommended. The optimization of fluid balance and vasoactive drug administration based on volumetric monitoring makes the transpulmonary indicator dilution technique a new option as an effective monitoring system during anesthesia for thoracic surgery when intravascular volume management is a primary objective.

Severe reperfusion lung injury after double lung transplantation.

AIM: To demonstrate the effects of combined inhaled nitric oxide and surfactant replacement as treatment for acute respiratory distress syndrome. This treatment has not previously been documented for reperfusion injury after double lung transplantation. METHOD: A 24-year-old female with cystic fibrosis underwent double lung transplantation. During implantation of the second lung a marked increase in pulmonary artery pressure associated with systemic hypotension, hypoxemia and low cardiac output were observed. Notwithstanding the patient received support from cardiovascular drugs and pulmonary vasodilators cardiopulmonary by-pass was necessary. In the intensive care unit the patient received the same drug support, inhaled nitric oxide and two bronchoscopic applications of bovine surfactant. RESULTS: A rapid improvement in PaO2/FiO2 within 2-3 hours of administration of surfactant was seen. The patient is well at follow-up 1 year post-transplant. CONCLUSION: There is a potential role for a combined therapy with inhaled nitric oxide and surfactant replacement in reperfusion injury after lung transplantation.