Accuracy of Doppler-estimated pulmonary vascular resistance in patients before liver transplantation

LTSI Consensus Guidelines: Preoperative Pulmonary Evaluation in Adult Liver Transplant Recipients

The relationship between chronic liver disease and respiratory symptoms and hypoxia is well recognized. Over the last century, three pulmonary complications specific to chronic liver disease (CLD) have been characterized: hepatopulmonary syndrome, portopulmonary hypertension, and hepatic hydrothorax. Apart from that coexisting pulmonary disease like chronic obstructive lung disease and interstitial lung disease also complicate the outcomes after liver transplantation (LT). Assessment for evaluation of underlying pulmonary disorders is essential to improve outcomes in patients with CLD, posted for LT. This consensus guideline of the Liver Transplant Society of India (LTSI) provides a comprehensive review of pulmonary issues in CLD, related and unrelated to underlying liver disease and gives recommendations for pulmonary screening in specific clinical scenarios in adults with chronic liver disease planned for LT. This document also aims to standardize the strategies for preoperative evaluation of these pulmonary issues in this subset of patients. Proposed recommendations were based on selected single case reports, small series, registries, databases, and expert opinion. The paucity of randomized, controlled trials in either of these disorders was noted. Additionally, this review will highlight the lacunae in our current evaluation strategy, challenges faced, and will provide direction to potentially useful futuristic preoperative evaluation strategies.

Echocardiographic estimation of pulmonary vascular resistance in advanced lung disease

Noninvasive assessment of pulmonary hemodynamics is often performed by echocardiographic estimation of the pulmonary artery systolic pressure (ePASP), despite limitations in the advanced lung disease population. Other noninvasive hemodynamic variables, such as echocardiographic pulmonary vascular resistance (ePVR), have not been studied in this population. We performed a retrospective analysis of 147 advanced lung disease patients who received both echocardiography and right heart catheterization for lung transplant evaluation. The ePVR was estimated by four previously described equations. Noninvasive and invasive hemodynamic parameters were compared in terms of correlation, agreement, and accuracy. The ePVR models strongly correlated with invasively determined PVR and had good accuracy with biases of <1 Wood units (WU), although with moderate precision and wide 95% limits of agreement varying from 5.9 to 7.8 Wood units. The ePVR models were accurate to within 1.9 WU in over 75% of patients. In comparison to the ePASP, ePVR models performed similarly in terms of correlation, accuracy, and precision when estimating invasive hemodynamics. In screening for pulmonary hypertension, ePVR models had equivalent testing characteristics to the ePASP. Mid-systolic notching of the right ventricular outflow tract Doppler signal identified a subgroup of 11 patients (7%) with significantly elevated PVR and mean pulmonary artery pressures without relying on the acquisition of a tricuspid regurgitation signal. Analysis of ePVR and determination of the notching pattern of the right ventricular outflow tract Doppler flow velocity envelope provide reliable insights into hemodynamics in advanced lung disease patients, although limitations in precision exist.

Hepatopulmonary Syndrome and Portopulmonary Hypertension: Current Status and Implications for Liver Transplantation

PURPOSE OF REVIEW

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PoPH) are both pulmonary vascular complications of advanced liver disease; however, these syndromes have distinct pathophysiology, clinical implications, and management.

RECENT FINDINGS

While both conditions are associated with portal hypertension, HPS results from diffuse pulmonary capillary vasodilation and PoPH results from vasoconstriction and vascular remodeling of pulmonary arteries. In HPS, no medical therapies clearly improve outcomes; however, patients have excellent post-LT outcomes with near uniform reversal of hypoxemia. In PoPH, several medical therapies used in idiopathic pulmonary hypertension have been shown improve pulmonary hemodynamics, symptoms, and potentially LT outcomes; however, further study is needed to determine best treatment regimens, long-term outcomes on medical therapy, and role of LT.

SUMMARY

While HPS results in severe hypoxemia that is usually reversible by LT, PoPH patients develop progressive pulmonary hypertension that may improve with medical therapy.

Role of echocardiography in screening for portopulmonary hypertension in liver transplant candidates: a meta-analysis

Objectives

To demonstrate the screening value of echocardiography for portopulmonary hypertension (POPH) in liver transplant candidates.

Design

Systematic review and meta-analysis.

Background

POPH is a complication of end-stage liver disease that adversely affects the outcome of orthotopic liver transplant. There are no specific symptoms in the early stage of POPH. POPH reduce the survival rate of patients with end-stage liver disease specially if they are not diagnosed. Therefore, early detection may improve prognosis. The objective of this study is to explore the screening value of echocardiography on liver transplant candidates for screening of POPH compared to right heart catheterization (RHC).

Method

PubMed, EMBASE and the Cochrane Library were searched by two independent reviewers for potentially eligible studies published up to 30 June 2019 to retrieve data based on per-patient analysis. STATA, Meta-DiSc, and RevMan were applied to perform this meta-analysis.

Results

Our search yielded 1576 studies, of which 11 satisfied the inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and area under the summary receiver operating characteristic (SROC) curve (AUC) of echocardiography for POPH were 0.85 (95% CI [0.65–0.94]), 0.83 (95% CI [0.73–0.90]), 4.99 (95% CI [3.03–8.21]), 0.19 (95% CI [0.07–0.46]), and 0.91 (95% CI [0.88–0.93]), respectively. Deeks’ funnel plot did not indicate the existence of publication bias (P = 0.66).

Conclusions

Echocardiography, a noninvasive modality, provides superior screening for POPH, but the diagnosis of POPH still requires RHC. PROSPERO registration number CRD42019144589.

The Use of Transthoracic Echocardiogram to Quantify Pulmonary Vascular Resistance in Patients with Systemic Sclerosis

OBJECTIVE

To explore the accuracy of tricuspid regurgitation velocity (TRV) to right ventricular outflow tract time-velocity integral (TVI_RVOT) ratio by Doppler to determine pulmonary vascular resistance (PVR) in patients with systemic sclerosis (SSc).

METHODS

Thirty-five consecutive adult patients with SSc, fulfilling the 2013 European League Against Rheumatism/American College of Rheumatology classification criteria, with sinus rhythm referred for right heart catheterization (RHC), were retrospectively included. All patients underwent a transthoracic echocardiogram (TTE) performed within 24 h of RHC. Patients with SSc were recruited regardless of disease activity, cardiac symptoms, and treatment regimen. Doppler measurements were compared to RHC measurements. A linear regression equation was generated to predict PVR by echocardiogram based on the TRV/TVI_RVOT ratio. The accuracy of Doppler measurements for predicting PVR > 3 Wood units was assessed by computing the areas under the receiver-operating characteristic curves.

RESULTS

There were 20 (57%) females in the study. The mean age was 65 ± 12 years. Mean and systolic pulmonary arterial pressures were 31 ± 8 and 53 ± 15 mmHg, respectively. There was a good correlation between TRV/TVI_RVOT ratio assessed by Doppler and PVR measured by RHC (R = 0.743, p < 0.001). The equation generated by this analysis was the following: PVR by Doppler = 11.3 × (TRV/TVI_RVOT) + 1.7. A cutoff value of 0.21 for TRV/TVI_RVOT ratio provided the best sensitivity (86%) and specificity (86%) to determine PVR > 3 Wood units.

CONCLUSION

Our study suggests that TTE using Doppler could be a useful and noninvasive tool for estimating PVR in patients with SSc.

Reliability of Doppler echocardiography in the assessment of high pulmonary vascular resistance in patients with severe pulmonary arterial hypertension

BACKGROUND

The objective is to assess whether the squaring of tricuspid regurgitation velocity (TRV) gives an improved estimate of pulmonary vascular resistance (PVR) or is equivalent to the ratio of TRV and time velocity integral of right ventricular outflow tract (TVI_RVOT) (TRV/TVI_RVOT) for assessing PVR in patients with high PVR values.

METHODS

Thirty patients predicted to have PVR >6 WU by Doppler were included in the present study. TRV and TVI_RVOT were measured by echo Doppler. TRV/TVI_RVOT and TRV²/TVI_RVOT were calculated. PVR_CATH was estimated within 2 h of Doppler study. Regression equations for calculating PVR from TRV/TVI_RVOT (PVR_ECHO1) and TRV²/TVI_RVOT (PVR_ECHO2) were developed. Bland-Altman analysis for agreement between PVR_CATH and PVR_ECHO1, PVR_ECHO2 was carried out.

RESULTS

The mean value of PVR_CATH was found to be 15.08 ± 7.03 WU. The calculated values of PVR_ECHO1 and PVR_ECHO2 were found to be 15.08 ± 6.34 WU and 15.05 ± 6.08 WU, respectively. The linear regression analysis carried out for PVR_CATH and TRV/TVI_RVOT showed good correlation (R = 0.84). Bland-Altman analysis showed excellent agreement between the two Doppler methods and invasive PVR with negligible bias.

CONCLUSION

Noninvasive estimation of PVR by Doppler is reliable even in patients with high PVR (>6 WU) and, squaring TRV is not superior to TRV alone.

Pulmonary vascular resistance versus pulmonary artery pressure for predicting right ventricular remodeling and functional tricuspid regurgitation

BACKGROUND

Pulmonary hypertension (PH) is a common cause of right ventricular (RV) remodeling and functional tricuspid regurgitation (FTR), but incremental pulmonary artery systolic pressure (PASP) does not always correlate with anatomic and functional RV changes. This study aimed to evaluate a noninvasive measure of pulmonary vascular resistance (PVR) for predicting RV dilatation, RV dysfunction, and severity of FTR.

METHODS

We prospectively analyzed consecutive stable patients with PASP ≥ 35 mm Hg or any degree of RV dilatation or dysfunction secondary to PH. Noninvasive PVR was calculated based on FTR peak velocity and flow in RV outflow tract.

RESULTS

We included 251 patients, aged 72.1 ± 11.4 years, 53% women, 74.9% with type 2 pulmonary hypertension. The mean PASP was 48.3 ± 12.2 mm Hg. Both PASP and PVR significantly correlated with FTR, RV dilatation, and RV systolic dysfunction. After dichotomizing FTR and RV dilatation and systolic dysfunction as nonsignificant vs significant, FTR and RV dilatation were similarly predicted by PASP and PVR, but RV dysfunction was better predicted by PVR (AUC = 0.78 [0.72-0.84] vs 0.66 [0.60-0.73] for PASP, P < 0.001). Patients with low PASP but high PVR showed worse RV and left ventricular function but lower rates of right heart failure and smaller inferior vena cava, compared to patients with high PASP but low PVR.

CONCLUSIONS

Noninvasive PVR was superior to PASP for predicting RV systolic dysfunction, but both were similarly associated with RV dilatation or FTR grade. PASP and PVR complement each other to define the echocardiographic findings and clinical status of the patient.

Portopulmonary hypertension

Portopulmonary hypertension (PoPH) refers to the condition that pulmonary arterial hypertension (PAH) occur in the stetting of portal hypertension. The development of PoPH is thought to be independent of the severity of portal hypertension or the etiology or severity of liver disease. PoPH results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. Untreated PoPH is associated with a poor prognosis. As PoPH is frequently asymptomatic or symptoms are generally non-specific, patients should be actively screened for the presence of PoPH. Two-dimensional transthoracic echocardiography is a useful non-invasive screening tool, but a definitive diagnosis requires invasive hemodynamic confirmation by right heart catheterization. Despite a dearth of randomized, prospective data, an ever-expanding clinical experience shows that patients with PoPH benefit from therapy with PAH-specific medications including with endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and/or prostanoids. Due to high perioperative mortality, transplantation should be avoided in those patients who have severe PoPH that is refractory to medical therapy.

A simple echocardiographic method to estimate pulmonary vascular resistance

Pulmonary hypertension includes heterogeneous diagnoses with distinct hemodynamic pathophysiologic features. Identifying elevated pulmonary vascular resistance (PVR) is critical for appropriate treatment. We reviewed data from patients seen at referral pulmonary hypertension clinics who had undergone echocardiography and right-side cardiac catheterization within 1 year. We derived equations to estimate PVR using the ratio of estimated pulmonary artery (PA) systolic pressure (PASPDoppler) to right ventricular outflow tract velocity time integral (VTI). We validated these equations in a separate sample and compared them with a published model based on the ratio of the transtricuspid flow velocity to right ventricular outflow tract VTI (model 1, Abbas et al 2003). The derived models were as follows: PVR = 1.2 × (PASP/right ventricular outflow tract VTI) (model 2) and PVR = (PASP/right ventricular outflow tract VTI) + 3 if notch present (model 3). The cohort included 217 patients with mean PA pressure of 45.3 ± 11.9 mm Hg, PVR of 7.3 ± 5.0 WU, and PA wedge pressure of 14.8 ± 8.1 mm Hg. Just >1/3 had a PA wedge pressure >15 mm Hg (35.5%) and 82.0% had PVR >3 WU. Model 1 systematically underestimated catheterization estimated PVR, especially for those with high PVR. The derived models demonstrated no systematic bias. Model 3 correlated best with PVR (r = 0.80 vs r = 0.73 and r = 0.77 for models 1 and 2, respectively). Model 3 had superior discriminatory power for PVR >3 WU (area under the curve 0.946) and PVR >5 WU (area under the curve 0.924), although all models discriminated well. Model 3-estimated PVR >3 was 98.3% sensitive and 61.1% specific for PVR >3 WU (positive predictive value 93%; negative predictive value 88%). In conclusion, we present an equation to estimate the PVR, using the ratio of PASPDoppler to right ventricular outflow tract VTI and a constant designating presence of right ventricular outflow tract VTI midsystolic notching, which provides superior agreement with catheterization estimates of PVR across a wide range of values.

Portopulmonary hypertension in cirrhotic patients: Prevalence, clinical features and risk factors

The incidence and clinical features of portopulmonary hypertension (POPH) have not been adequately described and it is currently unknown whether an association exists between the severity of POPH and liver function. Additionally, POPH risk factors are yet to be identified. The aim of this study was to determine the prevalence, describe the clinical features and investigate the potential risk factors of POPH. We conducted a study of 100 cirrhotic patients hospitalized between March 2011 and May 2012 at Tongji Hospital in Shanghai. The clinical characteristics of patients with and without POPH were analyzed. Clinical variables with a possible association with POPH were measured and pulmonary artery systolic pressure (PASP) was determined by cardiac Doppler echocardiography. Of the 100 patients enrolled in this study, 10 were diagnosed with POPH. Seven of the cases were mild, two were moderate and only one was severe; eight were attributed to viral infections. POPH was not detected in patients with schistosomal or alcoholic cirrhosis. Hemoglobin (Hb) levels were lower in patients with POPH compared to those without POPH (P<0.01) and the severity of POPH was not significantly correlated with Child-Pugh grade (R=−0.06, P=0.09). Hb levels, incidence of hepatitis C virus (HCV) infection and portal vein thrombosis differed between the two groups (P<0.05). Hb levels were identified as an independent risk factor associated with POPH and portal vein thrombosis may play an important role during the development of POPH. However, the severity of POPH was not associated with liver function.

A simple echocardiographic prediction rule for hemodynamics in pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) has diverse causes with heterogeneous physiology compelling distinct management. Differentiating patients with primarily elevated pulmonary vascular resistance (PVR) from those with PH predominantly because of elevated left-sided filling pressure is critical.

METHODS AND RESULTS

We reviewed hemodynamics, echocardiography, and clinical data for 108 patients seen at a referral PH clinic with transthoracic echocardiogram and right heart catheterization within 1 year. We derived a simple echocardiographic prediction rule to allow hemodynamic differentiation of PH attributed to pulmonary vascular disease (PH(PVD), defined as pulmonary artery wedge pressure [PAWP]≤15 mm Hg and PVR>3 WU). Age averaged 61.3±14.8 years, μPAWP and PVR were 16.4±7.1 mm Hg and 6.3±4.0 WU, respectively, and 52 (48.1%) patients fulfilled PH(PVD) hemodynamic criteria. The derived prediction rule ranged from -2 to +2 with higher scores suggesting higher probability of PH(PVD): +1 point for left atrial anterior-posterior dimension <3.2 cm; +1 for presence of a mid systolic notch or acceleration time <80 ms; -1 for lateral mitral E:e'>10; -1 for left atrial anterior-posterior dimension >4.2 cm. PVR increased stepwise with score (for -2, 0, and +2, μPVR were 2.5, 4.5, and 8.1 WU, respectively), whereas the inverse was true for pulmonary artery wedge pressure (corresponding μPAWP were 21.5, 16.5, and 10.4 mm Hg). Among subjects with complete data, the score had an area under the curve (AUC) of 0.921 for PH(PVD). A score ≥0 had 100% sensitivity and 69.3% positive predictive value for PH(PVD), with 62.3% specificity. No patients with a negative score had PH(PVD). Patients with a negative score and acceleration time >100 ms had normal PVR (μPVR=1.8 WU, range=0.7-3.2 WU).

CONCLUSIONS

We present a simple echocardiographic prediction rule that accurately defines PH hemodynamics, facilitates improved screening and focused clinical investigation for PH diagnosis and management.

Terlipressin improves pulmonary pressures in cirrhotic patients with pulmonary hypertension and variceal bleeding or hepatorenal syndrome

Terlipressin has been shown to improve both pulmonary and systemic hemodynamics in stable cirrhotic patients with pulmonary hypertension, whereas other vasoconstrictors may cause pulmonary pressures to deteriorate. We investigated the pulmonary and systemic hemodynamic effects of the first terlipressin dose (2 mg) in 7 cirrhotic patients with PH presenting with variceal bleeding (n=4) or hepatorenal syndrome (n=3). Terlipressin decreased pulmonary vascular resistance (158.8+/-8.9 vs 186.5+/-13.9 dynes · sec · cm-5; P=0.003) together with an increase in systemic vascular resistance (2143+/-126 vs 1643+/-126 dynes · sec · cm-5; P<0.001). Terlipressin should be the vasoconstrictor treatment of choice when patients present with variceal bleeding or HRS.

Noninvasive assessment of elevated pulmonary vascular resistance in children with pulmonary hypertension secondary to congenital heart disease: A comparative study between five different Doppler indices

BACKGROUND

Pulmonary vascular resistance (PVR) is an important hemodynamic parameter in patients with congenital heart disease (CHD). Noninvasive estimation of PVR represents an attractive alternative to invasive measurements.

METHODS

The study included 175 patients with pulmonary hypertension (PH) secondary to CHD. All patients underwent full echocardiographic study and invasive hemodynamic measurements. The study population was then subdivided into four subgroups. Each of the following Doppler indices was measured in one of these four subgroups: peak tricuspid regurgitant velocity (TRV), the ratio of the TRV to the velocity time integral of the right ventricular outflow tract (TRV/TVIRVOT), peak velocity of tricuspid annular systolic motion (TSm), heart rate corrected acceleration time and infliction time of the proximal left pulmonary artery (ATc, InTc). The data obtained was correlated with invasive PVR measurement. An ROC curve analysis was done to generate cutoff points with the highest balanced sensitivity and specificity to predict PVR > 6WU/m(2). The receiver operating characteristics (ROC) curves were compared with each other to determine the most reliable cutoff point in predicting elevated PVR > 6WU/m(2).

RESULTS

There was a significant correlation between both the TRV and TSm and invasive measurement of PVR (r = -0.511, 0.387 and P value = 0.0002, 0.006 respectively). The TSm and TRV cutoff values were the most reliable to predict elevated PVR > 6 WU/m(2). A TSm cutoff value of ⩽16.16 cm/s provided the best balanced sensitivity (85.7%) and specificity (66.7%) to determine PVRCATH > 6 WU/m(2). A cutoff value less than 7.62 cm/s had 100% specificity to predict PVRCATH > 6 WU/m(2). A TRV cutoff value of >3.96 m/s provided the best balanced sensitivity (66.7%) and specificity (100%) to determine PVRCATH > 6 WU/m(2). Both TRV and TSm had the highest area under the ROC curve among the 5 DOPPLER indices studied.

CONCLUSION

Prediction of elevated PVR in children with PH secondary to CHD could be achieved noninvasively using a number of Doppler indices. Among the five Doppler indices examined in the current study, the peak TRV and the TSm of the lateral tricuspid annulus had the highest balanced sensitivity and specificity to predict PVRI > 6 WU/m(2).

Estimation of pulmonary vascular resistance: correlation between echocardiography and catheterization data in patients with congenital heart disease

BACKGROUND

The ratio of peak tricuspid regurgitation velocity (TRV) and right ventricular outflow time-velocity integral (TVI RVOT) has been described as a good correlate of pulmonary vascular resistance (PVR). However, this method has not been well studied in congenital heart disease.

METHOD

Twenty patients with post-tricuspid shunt lesions who were planned to undergo cardiac catheterization were enrolled for the study. The ratio of TRV/TVI(RVOT) was measured via transthoracic echocardiography and correlated with invasively derived PVR (PVR(CATH)). PVR(CATH) was measured by cardiac catheterization. Fick's principle was used to calculate the pulmonary blood flow and oxygen consumption was assumed. Linear regression analysis was done to find the correlation between TRV/TVI(RVOT) and PVR(CATH).

RESULTS

There was a significant correlation between the two variables, r = 0.635(P = 0.003). Subgroup analysis revealed that this correlation was better at lower values of PVR(CATH) (r = 0.817 for PVR < 6 Wood units (WU)) than higher values (r = 0.659 for PVR > 6 WU). TRV/TVI(RVOT) ratio of greater than 0.145 predicted with 80% sensitivity and specificity a PVR > 6 WU.

CONCLUSIONS

There is modest correlation between TRV/TVI(RVOT) ratio and invasively derived PVR in congenital shunt lesions, especially in PVR < 6 WU. TRV/TVI(RVOT) ratio could be useful in identifying patients with congenital shunts whose PVR is likely to be <6 WU, and hence, do not need cardiac catheterization.

Circulating endotoxin and interleukin-6 levels are associated with Doppler-evaluated pulmonary vascular resistance in cirrhotic patients

PURPOSE

Endotoxin and interleukin-6 levels (IL-6) have been involved in the development of pulmonary hypertension (PH) in non-cirrhotic experimental models and subjects. High circulating levels of both substances have been detected in cirrhosis. The association between circulating endotoxin and IL-6 levels and echocardiographically evaluated pulmonary vascular resistance (PVR) in cirrhotic patients are investigated.

METHODS

Thirty-seven cirrhotic patients were studied: 25 with PVR <120 dynes s cm(-5) (group 1) and 12 with PVR >120 dynes s cm(-5) (group 2). Plasma endotoxin and serum IL-6 levels were measured. The PVR and cardiac output (CO) by Doppler ultrasound, mean arterial pressure (MAP), and systemic vascular resistance (SVR) as the ratio MAP/CO were evaluated.

RESULTS

Child-Pugh scores, MAP, CO, and SVR were similar in both groups. Endotoxin levels were correlated significantly with IL-6 levels (r = 0.342; P = 0.03). Endotoxin and IL-6 levels were significantly higher in group 2 compared to group 1 (2.26 [0.39-8.4] vs. 0.85 [0.37-7.6] EU/mL; P = 0.04 and 37.4 [7.85-106.5] vs. 8.36 [3.15-53.7] pg/mL; P < 0.001, respectively). The PVR was correlated significantly with endotoxin levels in group 2 (r = 0.587; P = 0.04) and with IL-6 levels in group 1 (r = 0.529; P = 0.01) and group 2 (r = 0.760; P = 0.004), respectively.

CONCLUSIONS

Our results suggest that endotoxin and IL-6 may contribute to cirrhosis-associated PH. In this regard, modulation of these substances could improve pulmonary pressures in cirrhotic patients.

Accuracy of Doppler-derived estimation of pulmonary vascular resistance in congenital heart disease: an index of operability

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease (CHD) accompanied by pulmonary arterial hypertension (PAH). Cardiac catheterization is the "gold standard" but is an invasive method for PVR measurement. A noninvasive and reliable method for estimation of PVR in children has been a major challenge and most desirable during past decades, especially for those who need repeated measurements. In a prospective study and among consecutive patients who were referred for cardiac catheterizations, PVR was calculated as the ratio of the transpulmonary pressure gradient (∆P) to the amount of the pulmonary flow (QP) accordingly for 20 patients with CHD and high PAH. Subsequently and noninvasively, PVR was assessed for these patients by a Doppler echocardiography-derived index defined as the ratio of the tricuspid regurgitation velocity (TRV(m/s)) to the velocity time integral (VTI(cm)) of the right-ventricular outflow tract (RVOT). There was a good correlation between PVR measured at catheterization (PVR(cath)) and TRV/VTI(m) ratio; the mean of three measurements of VTI (VTI(m)) with R (2) = 0.53 (p = 0.008). In addition, a TRV/VTI(m) value of 0.2 provided a sensitivity of 71.4% and a specificity of 100% for PVR >6 Woods units (WU) as well as sensitivity of 90% and specificity of 90% for a PVR equal to 8 WU. PVR value between 6 and 8 WU by catheterization has been considered as a cut-off point for intervention in children with left-to-right shunts and PAH. In conclusion, Doppler-derived TRV/VTI(m) ratio is a reliable index that may be helpful as a supplementary diagnostic tool for the selection of modality of treatment and follow-up of patients with PAH and increased PVR.

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.

Differential effects of terlipressin on pulmonary and systemic hemodynamics in patients with cirrhosis and pulmonary hypertension: an echo study

Terlipressin has been associated with pulmonary arterial vasodilation in patients with pulmonary hypertension (PH). We investigated the effects of terlipressin on pulmonary vascular resistance (PVR) in patients with cirrhosis without and with PH. Pulmonary vascular resistance and cardiac output (CO) by Doppler ultrasound, mean arterial pressure (MAP), and systemic vascular resistance (SVR) were evaluated in patients with cirrhosis with PVR -120 dyne s cm⁻⁵ (group 1, n = 20) and PVR >120 dyne s cm⁻⁵ (group 2, n = 10) before and 30 minutes after terlipressin infusion (2 mg). After terlipressin, PVR increased significantly in group 1 (96.1 ± 20.2 vs 85.1 ± 18 dyne s cm⁻⁵; P = .004) but decreased significantly in group 2 (170.4 ± 37.8 vs 157.8 ± 28.1 dyne s cm⁻⁵; P= .04). Pulmonary vascular resistance changes in group 2 correlated significantly with baseline PVR (r = -0.632; P = .04). Terlipressin induced a significant increase in MAP and SVR and a significant decrease in CO in both groups. Terlipressin significantly reduces pulmonary pressures in patients with cirrhosis having PH together with systemic hemodynamic improvement.

Scintigraphic evaluation of intrapulmonary shunt in normoxemic cirrhotic patients and effects of terlipressin

AIM

  The magnitude of intrapulmonary shunt (IPS) in cirrhotic patients without hypoxemia remains undefined. We evaluated the severity and clinical correlations of IPS in normoxemic cirrhotics, and possible IPS alterations after terlipressin treatment.

METHODS

  Fifteen patients with alcoholic cirrhosis without hypoxemia were studied at baseline and after the administration of 2 mg of terlipressin. The IPS fraction was evaluated by lung perfusion scan after the i.v. injection of technetium-99m-labeled macroaggregated albumin ((99m) Tc-MAA) and calculation of brain uptake (positive value ≥6%). Cardiac output (CO), pulmonary artery systolic pressure (PASP) and pulmonary vascular resistance (PVR) were evaluated by Doppler echocardiography. Mean arterial pressure (MAP) was measured and the ratio MAP/CO was calculated as an index of systemic vascular resistance (SVR). Portal vein velocity (PVV) and portal venous flow (PVF) were also assessed by Doppler ultrasonography.

RESULTS

  Three patients (20%) had an IPS fraction of more than 6%. A significant inverse correlation with platelet count (P = 0.001) and a direct correlation with Child-Pugh score (P = 0.06), PVV (P = 0.07) and PVF (P = 0.07) were noted. IPS fractions decreased significantly after terlipressin administration (P = 0.00001); the IPS fraction fell below 6% in all three patients with positive baseline values. Terlipressin treatment induced a significant decrease in CO (P = 0.003) and significant increases in MAP (P = 0.0003), SVR (P = 0.0003), SPAP (P = 0.001) and PVR (P = 0.01).

CONCLUSION

  IPS fractions detected by (99m) Tc-MAA lung scan were inversely correlated with platelet count and directly with liver disease severity, and found abnormal in 20% of normoxemic cirrhotic patients. Terlipressin reduced significantly the magnitude of the shunt.

Portopulmonary hypertension and right heart failure in patients with cirrhosis

PURPOSE OF REVIEW

In 5-6% of patients with portal hypertension a pathological state exists in which changes in the pulmonary vasculature cause an increase in pulmonary vascular resistance. The resultant increased work of the right ventricle may cause right heart failure and liver congestion. Patients with cirrhosis are at increased risk of mortality and transplant graft failure. The present review examines the latest advances in diagnosis, treatment and management of portopulmonary hypertension.

RECENT FINDINGS

Portopulmonary hypertension may be screened with transthoracic echocardiography and following up with a right heart catheterization in patients in whom the right ventricular systolic pressure is calculated to be 50 mmHg or greater. Therapy with prostanoids, endothelin-1 inhibitors and phosphodiesterase-5 inhibitors, or a combination of therapies, may be very effective in moderating pulmonary artery hypertension and, in selected patients, allowing liver transplantation to proceed safely. The model for end-stage liver disease (MELD) score is being weighted to accelerate responders on the waiting list for a transplant.

SUMMARY

Advances in diagnosis and therapy of portopulmonary hypertension allow patients with cirrhosis who respond to vasodilators to undergo liver transplantation safely. Unfortunately liver transplantation does not always result in reversal of pulmonary hypertension. There are now reports of de-novo pulmonary hypertension after liver transplantation.

Echocardiographic assessment of pulmonary vascular resistance in pulmonary arterial hypertension

BACKGROUND

Echocardiographic ratio of peak tricuspid regurgitant velocity to the right ventricular outflow tract time-velocity integral (TRV/TVI rvot) was presented as a reliable non-invasive method of estimating pulmonary vascular resistance (PVR). Studies using this technique in patients with moderate to high PVR are scarce. Left ventricular outflow tract time-velocity integral (TVI lvot) can be easier to measure than TVI rvot, especially in patients with severe pulmonary hypertension (PH) with significant anatomical modifications of the right structures.

AIMS

We wanted to determine whether the TRV/TVI rvot and TRV/TVI lvot ratios would form a reliable non-invasive tool to estimate PVR in a cohort of patients with moderate to severe pulmonary vascular disease.

METHODS

Doppler echocardiographic examination and right heart catheterisation were performed in 37 patients. Invasive PVR was compared with TRV/TVI rvot and TRV/TVI lvot ratios using regression analysis. Two equations were modelled and the results compared with invasive measurements using the Bland-Altman analysis. Using receiver-operating characteristics curve analysis, a cut-off value for the two ratios was generated.

RESULTS

Correlation coefficients between invasive PVR and TRV/TVI rvot then TRV/TVI lvot were respectively 0.76 and 0.74. Two new equations were found but the Bland-Altman analysis showed wide standard deviations (respectively 3.8 and 3.9 Wood units). A TRV/TVI rvot then TRV/TVI lvot ratio cut-off value of 0.14 had a sensitivity of 93% and a specificity of 57% for the first and a sensitivity of 87% and a specificity of 57% for the second to determine PVR > 2 Wood units.

CONCLUSION

Echocardiography is useful for the screening of patients with pulmonary hypertension and PVR > 2 WU. It remains disappointing for accurate assessment of high PVR. TVI lvot may be an alternative to TVI rvot for patients for whom accurate TVI rvot measurement is not possible.

Anesthetic management of hepatic transplantation

PURPOSE OF REVIEW

The present review describes new trends and ongoing controversies in the anesthetic care of liver transplant recipients.

RECENT FINDINGS

Recent studies have improved our knowledge of conditions increasing perioperative risk, such as portopulmonary hypertension and renal failure. Improved surgical and anesthetic management has reduced intraoperative blood loss, as more studies identify an independent association between blood transfusion and poor outcome. New concepts in the coagulopathy of liver failure are emerging, with clear implications for clinical practice, including greater awareness of the risks of intraoperative thromboembolism. Less invasive intraoperative hemodynamic monitoring has been advocated, as has wider use of transoesophageal echocardiography. Early extubation is becoming more routinized.

SUMMARY

Anesthetic management still varies widely between liver transplant centers with little data to indicate best practice. Future research should focus on fluid replacement, prevention and treatment of coagulopathy, care of the acutely ill patient and the safety and benefits of early extubation.