Indocyanine green plasma disappearance rate during relief of increased abdominal pressure

Continuous passive paracentesis versus large-volume paracentesis in the prevention and treatment of intra-abdominal hypertension in the critically ill cirrhotic patient with ascites (COPPTRIAHL): study protocol for a randomized controlled trial

BACKGROUND

Critically ill patients with cirrhosis and ascites are at high risk for intra-abdominal hypertension (IAH) which increases mortality. Clinical guidelines recommend maintaining intra-abdominal pressure (IAP) below 16 mmHg; nonetheless, more than three quarters of critically ill patients with cirrhosis develop IAH during their first week of ICU stay. Standard-of-care intermittent large-volume paracentesis (LVP) relieves abdominal wall tension, reduces IAP, optimizes abdominal perfusion pressure, and is associated with short-term improvement in renal and pulmonary dysfunction. However, there is no evidence of the superiority of different paracentesis strategies in the prevention and treatment of IAH in critically ill patients with cirrhosis. This trial aims to compare the outcomes of continuous passive paracentesis versus LVP in the prevention and treatment of IAH in patients with cirrhosis and ascites.

METHODS

An investigator-initiated, open label, randomized controlled trial, set in a general ICU specialized in liver disease, was initiated in August 2022, with an expected duration of 36 months. Seventy patients with cirrhosis and ascites will be randomly assigned, in a 1:1 ratio, to receive one of two methods of therapeutic paracentesis. A stratified randomization method, with maximum creatinine and IAP values as strata, will homogenize patient baseline characteristics before trial group allocation, within 24 h of admission. In the control group, LVP will be performed intermittently according to clinical practice, with a maximum duration of 8 h, while, in the intervention group, continuous passive paracentesis will drain ascitic fluid for up to 7 days. The primary endpoint is serum creatinine concentration, and secondary endpoints include IAP, measured creatinine clearance, daily urine output, stage 3 acute kidney injury and multiorgan dysfunction assessed at day 7 after enrollment, as well as 28-day mortality rate and renal replacement therapy-free days, and length-of-stay. Prespecified values will be used in case of renal replacement therapy or, beforehand ICU discharge, liver transplant and death. Safety analysis will include paracentesis-related complication rate and harm. Data will be analyzed with an intention-to-treat approach.

DISCUSSION

This is the first trial to compare the impact of different therapeutic paracentesis strategies on organ dysfunction and outcomes in the prevention and treatment of IAH in critically ill patients with cirrhosis and ascites.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04322201 . Registered on 20 December 2019.

Abdominal perfusion pressure in critically ill cirrhotic patients: a prospective observational study

In critical patients, abdominal perfusion pressure (APP) has been shown to correlate with outcome. However, data from cirrhotic patients is scarce. We aimed to characterize APP in critically ill cirrhotic patients, analyze the prevalence and risk factors of abdominal hypoperfusion (AhP) and outcomes. A prospective cohort study in a general ICU specialized in liver disease at a tertiary hospital center recruited consecutive cirrhotic patients between October 2016 and December 2021. The study included 101 patients, with a mean age of 57.2 (± 10.4) years and a female gender proportion of 23.5%. The most frequent etiology of cirrhosis was alcohol (51.0%), and the precipitant event was infection (37.3%). ACLF grade (1-3) distribution was 8.9%, 26.7% and 52.5%, respectively. A total of 1274 measurements presented a mean APP of 63 (± 15) mmHg. Baseline AhP prevalence was 47%, independently associated with paracentesis (aOR 4.81, CI 95% 1.46-15.8, p = 0.01) and ACLF grade (aOR 2.41, CI 95% 1.20-4.85, p = 0.01). Similarly, AhP during the first week (64%) had baseline ACLF grade (aOR 2.09, CI 95% 1.29-3.39, p = 0.003) as a risk factor. Independent risk factors for 28-day mortality were bilirubin (aOR 1.10, CI 95% 1.04-1.16, p < 0.001) and SAPS II score (aOR 1.07, CI 95% 1.03-1.11, p = 0.001). There was a high prevalence of AhP in critical cirrhotic patients. Abdominal hypoperfusion was independently associated with higher ACLF grade and baseline paracentesis. Risk factors for 28-day mortality included clinical severity and total bilirubin. The prevention and treatment of AhP in the high-risk cirrhotic patient is prudential.

Liver function assessment by indocyanine green plasma disappearance rate in patients with intra-abdominal hypertension after "non-hepatic" abdominal surgery

BACKGROUND AND OBJECTIVE

Liver function assessment in patients with intra-abdominal hypertension (IAH) after major abdominal surgery is complex and often confounding. Elevated intra-abdominal pressure (IAP) often occurs after major abdominal surgery, and is associated with decreased abdominal blood flow and organ dysfunction, and it could cause abdominal compartment syndrome (ACS), which is a life-threatening condition. Plasma disappearance rate (PDR) of indocyanine green (ICG) and ICG retention rate after 15 min (R15) were used to evaluate liver function and as a prognostic parameter after major abdominal surgery.

METHODS

In this prospective/observational study, 51 patients were followed in the surgical intensive care unit after major abdominal surgery (operation of the small and large intestine, stomach, pancreas, spleen, or resection of the abdominal aorta), 29 had IAH. The PDR-ICG and R15 were analyzed 24 h after surgery concurrently with IAP, APP, bilirubin, AST, ALT, prothrombin time, albumin, cardiac index, arterial lactate, oxygen delivery, MAP (mean arterial pressure), APACHE II (acute physiology and chronic health evaluation), SOFA (sequential organ failure assessment), and SAPS II (simplified acute physiology score). IAH has been defined as a peak intra-abdominal pressure (IAP) value of ≥12 mmHg, at a minimum, as two standardized measurements obtained 1-6 h apart.

RESULTS

The PDR-ICG measured 24 h after surgery was not different among groups (20.95% [SD = 10.34] vs 25.40% [SD = 7.42]), p = .094. ICG R15 was significantly higher in patients with IAH, 11.10% [SD = 13.82] vs 8.30 [SD = 11.46], p < .05, respectively. The PDR/ICG value was significantly lower in non-survivors than survivors (16.82 [SD = 10.87] vs 24.35 [SD = 8.48], p < .05).

CONCLUSIONS

The results suggest that PDR/ICG and ICG R15 are useful dynamic tests for evaluation of complex liver function and survival prediction after major abdominal surgery in patients with IAH.

Large-volume paracentesis effects plasma disappearance rate of indo-cyanine green in critically ill patients with decompensated liver cirrhosis and intraabdominal hypertension

BACKGROUND

Ascites is a major complication of decompensated liver cirrhosis. Intraabdominal hypertension and structural alterations of parenchyma involve decisive changes in hepatosplanchnic blood flow. Clearance of indo-cyanine green (ICG) is mainly dependent on hepatic perfusion and hepatocellular function. As a consequence, plasma disappearance rate of ICG (ICG-PDR) is rated as a useful dynamic parameter of liver function. This study primarily evaluates the impact of large-volume paracentesis (LVP) on ICG-PDR in critically ill patients with decompensated cirrhosis. Additionally, it describes influences on intraabdominal pressure (IAP), abdominal perfusion pressure (APP), hepatic blood flow, hemodynamic and respiratory function.

METHODS

We analyzed LVP in 22 patients with decompensated liver cirrhosis. ICG-PDR was assessed by using noninvasive LiMON technology (Pulsion® Medical Systems; Maquet Getinge Group), and hepatic blood flow was analyzed by color-coded duplex sonography.

RESULTS

Paracentesis of a median volume of 3450 mL ascites evoked significant increases of ICG-PDR from 3.6 (2.8-4.6) to 5.1 (3.9-6.2)%/min (p < 0.001). Concomitantly, we observed a raise in "ICG-Clearance" from 99 (73.5-124.5) to 104 (91-143.5) mL/min/m2 (p = 0.005), while circulating blood volume index was unchanged [2412 (1983-3025) before paracentesis vs. 2409 (1997-2805) mL/m2, p = 0.734]. Sonography revealed a significant impact of paracentesis on hepatic blood flow: Hepatic artery resistance index dropped from 0.74 (0.68-0.75) to 0.68 (0.65-0.71) (p < 0.001) and maximum flow velocity in hepatic vein increased from 24 (17-30) to 30 (22-36) cm/s (p < 0.001). Consistent with previous studies, paracentesis caused significant decreases in IAP from 19.0 (15.0-20.3) to 11.0 (8.8-12.3) mmHg (p < 0.001) and central venous pressure from 22.5 (17.8-29.0) to 17.5 (12.8-24.0) mmHg (p < 0.001) with inverse increases in APP from 63.0 (56.8-69.5) to 71.0 (65.5-78.5) mmHg (p < 0.001). Changes in ICG-PDR were concomitant with changes in IAP (r = - 0.602) and APP (r = 0.576). Moreover, we found a substantial improvement in respiratory function. By contrast, hemodynamic parameters assessed by transpulmonary thermodilution, serum bilirubin and international normalized ratio did not change after paracentesis.

CONCLUSION

Critically ill patients with decompensated cirrhosis and elevated IAP showed dramatically impaired ICG-PDR. Paracentesis evoked an improvement in ICG-PDR in parallel with a decreased IAP and an increased APP, while conventional parameters of liver function did not change. This effect on ICG-PDR is mainly referable to a relief of intraabdominal hypertension and changes in hepatosplanchnic blood flow.

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of ¹³C-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a ¹³C-methacetin breath test (¹³C-MBT). SI values from before (SI_pre) and 20 min after (SI_post) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of ¹³C-MBT values to SI_post and RE to obtain a SI-based estimation of ¹³C-MBT values. The simple regression model showed a log-linear correlation of ¹³C-MBT values with SI_post and RE (p < 0.001). Stratified by 3 different categories of ¹³C-MBT readouts, there was a constant significant decrease in both SI_post (p ≤ 0.002) and RE (p ≤ 0.033) with increasing liver disease progression as assessed by the ¹³C-MBT. Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using SI-based indices.

Indocyanine green plasma disappearance rate as dynamic liver function test in critically ill patients

BACKGROUND

Indocyanine green (ICG) is a water-soluble fluorescent dye that is bound to plasma protein when administered intravenously. Removal of ICG from the blood depends on hepatic blood flow, function of the parenchymal cells and biliary excretion. ICG elimination is described as a useful dynamic liver function test.

METHODS

In this review, we looked at the most recent literature to clarify why ICG is useful in critically ill patients, the validity of the ICG plasma disappearance rate (ICG-PDR) measured transcutaneously and whether ICG-PDR has any prognostic value.

CONCLUSION

In conclusion, measuring ICG-PDR is a valuable method for dynamic assessment of liver function, and is found to be a valuable prognostic tool in predicting survival for septic patients, patients presenting with acute liver failure and critically ill patients.

Green light for liver function monitoring using indocyanine green? An overview of current clinical applications

The dye indocyanine green is familiar to anaesthetists, and has been studied for more than half a century for cardiovascular and hepatic function monitoring. It is still, however, not yet in routine clinical use in anaesthesia and critical care, at least in Europe. This review is intended to provide a critical analysis of the available evidence concerning the indications for clinical measurement of indocyanine green elimination as a diagnostic and prognostic tool in two areas: its role in peri-operative liver function monitoring during major hepatic resection and liver transplantation; and its role in critically ill patients on the intensive care unit, where it is used for prediction of mortality, and for assessment of the severity of acute liver failure or that of intra-abdominal hypertension. Although numerous studies have demonstrated that indocyanine green elimination measurements in these patient populations can provide diagnostic or prognostic information to the clinician, 'hard' evidence - i.e. high-quality prospective randomised controlled trials - is lacking, and therefore it is not yet time to give a green light for use of indocyanine green in routine clinical practice.

Relationship between intra-abdominal pressure and indocyanine green plasma disappearance rate: hepatic perfusion may be impaired in critically ill patients with intra-abdominal hypertension

Background

Monitoring hepatic blood flow and function might be crucial in treating critically ill patients. Intra-abdominal hypertension is associated with decreased abdominal blood flow, organ dysfunction, and increased mortality. The plasma disappearance rate (PDR) of indocyanine green (ICG) is considered to be a compound marker for hepatosplanchnic perfusion and hepatocellular membrane transport and correlates well with survival in critically ill patients. However, correlation between PDR_ICG and intra-abdominal pressure (IAP) remains poorly understood. The aim of this retrospective study was to investigate the correlation between PDR_ICG and classic liver laboratory parameters, IAP and abdominal perfusion pressure (APP). The secondary goal was to evaluate IAP, APP, and PDR_ICG as prognostic factors for mortality.

Methods

A total of 182 paired IAP and PDR_ICG measurements were performed in 40 critically ill patients. The mean values per patient were used for comparison. The IAP was measured using either a balloon-tipped stomach catheter connected to an IAP monitor (Spiegelberg, Hamburg, Germany, or CiMON, Pulsion Medical Systems, Munich, Germany) or a bladder FoleyManometer (Holtech Medical, Charlottenlund, Denmark). PDR_ICG was measured at the bedside using the LiMON device (Pulsion Medical Systems, Munich, Germany). Primary endpoint was hospital mortality.

Results

There was no significant correlation between PDR_ICG and classic liver laboratory parameters, but PDR_ICG did correlate significantly with APP (R = 0.62) and was inversely correlated with IAP (R = -0.52). Changes in PDR_ICG were associated with significant concomitant changes in APP (R = 0.73) and opposite changes in IAP (R = 0.61). The IAP was significantly higher (14.6 ± 4.6 vs. 11.1 ± 5.3 mmHg, p = 0.03), and PDR_ICG (10 ± 8.3 vs. 15.9 ± 5.2%, p = 0.02) and APP (43.6 ± 9 vs. 57.9 ± 12.2 mmHg, p < 0.0001) were significantly lower in non-survivors.

Conclusions

PDR_ICG is positively correlated to APP and inversely correlated to IAP. Changes in APP are associated with significant concomitant changes in PDR_ICG, while changes in IAP are associated with opposite changes in PDR_ICG, suggesting that an increase in IAP may compromise hepatosplanchnic perfusion. Both PDR_ICG and IAP are correlated with outcome. Measurement of PDR_ICG may be a useful additional clinical tool to assess the negative effects of increased IAP on liver perfusion and function.

Effects of intra-abdominal pressure on liver function assessed with the LiMON in critically ill patients

BACKGROUND

Intra-abdominal pressure (IAP) and intra-abdominal hypertension (IAH) are associated with significant morbidity and mortality in critically ill patients. Our aim was to assess the effects of IAH on liver function using the noninvasive liver function monitoring system LiMON and to assess the prognostic value of IAP in critically ill patients.

METHODS

We conducted a retrospective analysis of critically ill patients who were treated in the intensive care unit (ICU). The IAP and indocyanine green plasma disappearance rate (ICG-PDR) measurements were made within 24 hours after admission to the ICU and repeated 12 hours later. Intra-abdominal pressure was measured via a Foley bladder catheter, and ICG elimination tests were conducted concurrently using the LiMON.

RESULTS

We included 30 critically ill patients (17 women and 13 men aged 28-89 yr) in our analysis. Statistical analysis showed that the baseline IAP values were significantly higher among nonsurvivors than survivors (19.38 [standard deviation; SD 2.08] v. 13.07 [SD 0.99]). The twelfth-hour IAP values were higher than baseline measurements among nonsurvivors (21.50 [SD 1.96]) and lower than baseline measurements among survivors (11.71 [SD 1.54]); the difference between groups was significant (p < 0.001). The baseline ICG-PDR values were significantly lower among nonsurvivors than survivors (10.86 [SD 3.35] v. 24.51 [SD 6.78]), and the twelfth-hour ICGPDR values were decreased in all groups; the difference between groups was significant (p < 0.001).

CONCLUSION

Our results suggest that measurement of ICG-PDR with the LiMON is a good predictor of the effects of IAP on liver function and, thus, can be recommended for the evaluation of critically ill patients.