Effect of norepinephrine infusion on hepatic blood flow and its interaction with somatostatin: an observational cohort study

Background

Norepinephrine (NE) is a α₁-adrenergic mediated vasopressor and a key player in the treatment of perioperative hypotension. Apart from modulating systemic hemodynamics, NE may also affect regional blood flow, such as the hepatic circulation, which contains a wide variety of adrenergic receptors. It may alter regional vascular tonus and hepatic blood flow (HBF) by reducing portal vein flow (PVF) or hepatic arterial flow (HAF). The aim of this study was to assess the effects of NE on HBF.

Methods

Patients scheduled for pancreaticoduodenectomy were included. All patients received standardized anesthetic care using propofol and remifentanil and were hemodynamically stabilized using a goal-directed hemodynamic strategy guided by Pulsioflex™. On surgical indication, somatostatin (SOMATO) was given to reduce pancreatic secretion. HBF measurements were performed using transit-time ultrasound (Medistim™). Baseline hemodynamic and HBF measurements were made after pancreatectomy, at T1. Afterwards, NE infusion was initiated to increase mean arterial pressure (MAP) by 10 – 20% of baseline MAP (T2) and by 20 – 30% of baseline MAP (T3). HBF and hemodynamic measurements were performed simultaneously at these three time-points.

Results

A total of 28 patients were analyzed. Administration of NE significantly increased MAP but had no effect on cardiac index. NE infusion reduced total HBF in all patients (p < 0.01) by a reduction HAF (p < 0.01), while the effect on PVF remained unclear. Post-hoc analysis showed that SOMATO-treated patients had a significant lower PVF at baseline (p < 0.05), which did not change during NE infusion. In these patients, reduction of total HBF was primarily related to a reduction of HAF (p < 0.01). In untreated patients, NE infusion reduced total HBF both by a reduction HAF (p < 0.01) and PVF (p < 0.05).

Conclusion

Administration of NE reduced total HBF, by decreasing HAF, while the effect on PVF remained unclear. SOMATO-treated patients had a lower PVF at baseline, which remained unaffected during NE infusion. In these patients the decrease in total HBF with NE was entirely related to the decrease in HAF. In SOMATO-untreated patients PVF also significantly decreased with NE.

Trial registration

Study protocol EC: 2019/0395.

EudraCT n°: 2018–004,139-66 (25 – 03 – 2019).

Clin.trail.gov: NCT03965117 (28 – 05 – 2019).

Hepatic pseudolesions caused by alterations in intrahepatic hemodynamics

Hepatic pseudolesion may occur in contrast-enhanced computed tomography and magnetic resonance imaging due to the unique haemodynamic characteristics of the liver. The concept of hepatic arterial buffer response (HABR) has become mainstream for the understanding of the mechanism of the reciprocal effect between hepatic arterial and portal venous flow. And HABR is thought to be significantly related to the occurrence of the abnormal imaging findings on arterial phase of contrast enhanced images, such as hepatic arterial-portal vein shunt and transient hepatic attenuation difference, which mimic hypervascular tumor and may cause clinical problems. Third inflow to the liver also cause hepatic pseudolesion, and some of the cases may show histopathologic change such as focal hyperplasia, focal fatty liver, and focal sparing of fatty liver, and called pseudotumor. To understand these phenomena might be valuable for interpreting the liver imaging findings.

Hepatic blood volume is decreased in patients with cirrhosis and does not decrease further after a meal like in healthy persons

BACKGROUND & AIMS

The aim was to measure fractional hepatic blood volume (HBV) and hepatic blood flow (HBF) before and after a meal in patients with cirrhosis (n = 7) and healthy persons (n = 6).

METHODS

Catheters were placed in a radial artery and a hepatic vein for blood sampling and a peripheral vein for indocyanine green (ICG) infusion. A 6-min positron emission tomography (PET) liver scan was performed after inhalation of 1000 MBq ¹⁵O-CO and repeated after ingestion of a standard meal. HBV was calculated as the ¹⁵O-CO concentration in liver tissue (PET) divided by that in arterial blood. HBF was calculated from ICG infusion rate and arterial and hepatic venous blood concentrations according to Fick's principle.

RESULTS

Mean fasting HBV was 14 mL blood/100 mL liver tissue in patients with cirrhosis and 21 mL blood/100 mL liver tissue in healthy subjects (p < .01). Mean HBV did not change postprandially in patients with cirrhosis (13 mL blood/100 mL liver tissue) but decreased in healthy subjects (17 mL blood/100 mL liver tissue; p = .02). Mean fasting HBF was 1.5 L blood/min in patients with cirrhosis and 1.1 L blood/min in healthy subjects and increased in both groups of subjects to 1.8 L blood/min.

CONCLUSIONS

Fasting HBV was lower in patients with cirrhosis and did not decrease postprandially as it did in the healthy controls although the HBF increased equally. Patients with cirrhosis thus have a disturbed hemodynamic response to normo-physiological changes such as a meal.

Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

BACKGROUND

The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound (TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI (PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events.

METHODS

Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery (Qha), the portal vein (Qpv), and the aorta above the celiac trunk (Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression (PLS) model was implemented.

RESULTS

The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32% (95% CI: -49% to 15%); Qha 17% (95% CI: -15% to 51%); and Qpv 40% (95% CI: -62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI (β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively).

CONCLUSIONS

There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.

Assessment of liver perfusion and function by indocyanine green in the perioperative setting and in critically ill patients

Indocyanine green (ICG) is a water-soluble dye that is bound to plasma proteins when administered intravenously and nearly completely eliminated from the blood by the liver. ICG elimination depends on hepatic blood flow, hepatocellular function and biliary excretion. ICG elimination is considered as a useful dynamic test describing liver function and perfusion in the perioperative setting, i.e., in liver surgery and transplantation, as well as in critically ill patients. ICG plasma disappearance rate (ICG-PDR) which can be measured today by transcutaneous systems at the bedside is a valuable method for dynamic assessment of liver function and perfusion, and is regarded as a valuable prognostic tool in predicting survival of critically ill patients, presenting with sepsis, ARDS or acute liver failure.

Changes in duration of action of rocuronium following decrease in hepatic blood flow during pneumoperitoneum for laparoscopic gynaecological surgery

Background

A moderate insufflation pressure and deep neuromuscular blockade (NMB) have been recommended in laparoscopic surgery in consideration of the possible reduction in splanchnic perfusion due to the CO₂-pneumoperitoneum. Since the liver is the major organ for rocuronium metabolism, the question of whether NMB of rocuronium would change with the variation of liver perfusion during pneumoperitoneum during laparoscopic surgery merits investigation.

Methods

In this prospective study, a total of sixty female patients scheduled for either selective laparoscopic gynaecological surgery (group laparoscopy) or laparotomy for gynaecological surgery (group control) were analyzed. Rocuronium was administered with closed-loop feedback infusion system, which was also applied to monitor NMB complied with good clinical research practice (GCRP). The onset time, clinical duration, and recovery index were measured. Hepatic blood flow was assessed by laparoscopic intraoperative ultrasonography before insufflation/after entering the abdominal cavity (T1), 5 min after insufflation in the Trendelenburg position/5 min after skin incision (T2), 15 min after insufflation in the Trendelenburg position/15 min after skin incision (T3), 30 min after insufflation in the Trendelenburg position/30 min after skin incision (T4), and 5 min after deflation/before closing the abdomen (T5) in group laparoscopy/group control respectively. The relationship between the clinical duration of rocuronium and portal venous blood flow was analyzed using linear or quadratic regression.

Result

The clinical duration and RI of rocuronium were both prolonged significantly in group laparoscopy (36.8 ± 8.3 min; 12.8 ± 5.5 min) compared to group control (29.0 ± 5.8 min; 9.8 ± 4.0 min) (P < 0.0001; P = 0.018). A significant decrease was found in portal venous blood flow during the entire pneumoperitoneum period in group laparoscopy compared with group control (P < 0.0001). There was a significant correlation between the clinical duration of rocuronium and portal venous blood flow (Y = 51.800-0.043X + (1.86E-005) X²; r² = 0.491; P < 0.0001).

Conclusion

Rocuronium-induced NMB during laparoscopic gynaecological surgery might be prolonged due to the decrease in portal venous blood flow induced by CO₂-pneumoperitoneum. Less rocuronium could be required to achieve a desirable NMB in laparoscopic gynaecological surgery.

Trial registration

ChiCTR. Registry number: ChiCTR-OPN-15007524. Date of registration: December 4, 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0335-1) contains supplementary material, which is available to authorized users.

Time-Harmonic Elastography of the Liver is Sensitive to Intrahepatic Pressure Gradient and Liver Decompression after Transjugular Intrahepatic Portosystemic Shunt (TIPS) Implantation

We investigated the correlation between hepatic venous pressure gradient (HVPG) and liver shear wave speed (SWS) measured by multi-frequency time-harmonic ultrasound elastography (THE) before and after transjugular intrahepatic portosystemic shunt (TIPS) implantation. Ten patients with ascites, cirrhotic liver disease and portal hypertension were prospectively examined with invasive HVPG measurement and THE before and after TIPS implantation. HVPG and SWS decreased after TIPS placement from 20.4 ± 2.2 mmHg to 9.8 ± 4.1 mmHg (mean ± standard deviation) and from 3.87 ± 0.54 m/s to 3.27 ± 0.44 m/s. Mean reduction HVPG was -10.6 ± 3.7 mmHg, p < 0.001; mean reduction SWS was -0.60 ± 0.29 m/s, p < 0.001. A linear correlation was observed between HVPG and SWS (R = 0.59, p = 0.0061). THE-measured SWS is a first potential direct ultrasound marker for liver decompression following TIPS in ascites-associated cirrhotic liver disease and therefore might be suitable to non-invasively detect portal hypertension.

CEUS and Fibroscan in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

AIM: To determine intra-hepatic blood flow and liver stiffness in patients with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) using contrast-enhanced ultrasound and fibroscan.

METHODS: This prospective study included 15 patients with NAFLD, 17 patients with NASH and 16 healthy controls. In each patient, real-time ultrasound was used to locate the portal vein (PV) and the right liver lobe, and 5 mL of SonoVue^® was then injected intravenous in a peripheral vein of the left arm over a 4-s span. Digital recording was performed for 3 min thereafter. The recording was subsequently retrieved to identify an area of interest in the PV area and in the right liver parenchyma (LP) to assess the blood flow by processing the data using dedicated software (Qontrast^®, Bracco, Italy). The following parameters were evaluated: percentage of maximal contrast activity (Peak%), time to peak (TTP, s), regional blood volume (RBV, cm³), regional blood flow (RBF, cm³/s) and mean transit time (MTT, s). At 24-48 h post-injection, liver stiffness was evaluated using Fibroscan and measured in kPa. The statistical evaluation was performed using Student’s t test.

RESULTS: In the PV, the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patients compared with the controls (Peak%: NAFLD 26.3 ± 6.6, NASH 28.1 ± 7.3 vs controls 55.8 ± 9.9, P < 0.001; RBV: NAFLD 4202.3 ± 3519.7, NASH 3929.8 ± 1941.3 vs controls 7473 ± 3281, P < 0.01; RBF: NAFLD 32.5 ± 10.8, NASH 32.7 ± 12.1 vs controls 73.1 ± 13.9, P < 0.001). The TTP in the PV was longer in both patient groups but reached statistical significance only in the NASH patients compared with the controls (NASH 79.5 ± 37.8 vs controls 43.2 ± 30, P < 0.01). In the LP, the Peak%, RBV and RBF were significantly reduced in the NAFLD and NASH patients compared with the controls (Peak%: NAFLD 43.2 ± 7.3, NASH 41.7 ± 7.7 vs controls 56.6 ± 6.3, P < 0.001; RBV: NAFLD 4851.5 ± 2009, NASH 5069.4 ± 2292.5 vs controls 6922.9 ± 2461.5, P < 0.05; RBF: NAFLD 55.7 ± 10.1, NASH 54.5 ± 12.1 vs controls 75.9 ± 10.5, P < 0.001). The TTP was longer in both patient groups but did not reach statistical significance. The MTT in both the PV and LP in the NAFLD and NASH patients was not different from that in the controls. Liver stiffness was significantly increased relative to the controls only in the NASH patients (NASH: 6.4 ± 2.2 vs controls 4.6 ± 1.5, P < 0.05).

CONCLUSION: Blood flow derangement within the liver present not only in NASH but also in NAFLD suggests that a vascular flow alteration precedes liver fibrosis development.

Validation of 3D power Doppler and VOCAL software in the sonographic assessment of hepatic venous flow



AIM

To evaluate the reproducibility of three-dimensional power Doppler ultrasonography (3D-PDU) and the repeatability of Virtual Organ Computer-aided AnaLysis (VOCAL) software in the assessment of hepatic venous flow in ten healthy non-pregnant individuals.

METHODS

Visualization of hepatic veins was performed using both intra- and subhepatic approaches; These examinations were repeated twice. Vascular indices were obtained for each examination in a reference point using both small and large volume samples (3 times per type of volume sample). Intraclass Correlation Coefficients and Pearson's Product-Moment Correlation Coefficient were calculated to assess reproducibility and repeatability, respectively.

RESULTS

Intraclass Correlation Coefficients were more than 0.60 in small volumes, but variable in large volumes for both approaches. However, re-identification of the reference point failed in 30% using the subhepatic approach. Repeatability was high for all VOCAL analyses (Pearson's Product-Moment Correlation Coefficient > 0.98).

CONCLUSIONS

These results indicate reliable use of intrahepatic small volume samples in clinical application and invite to explore the role of this technology in the assessment of hepatic venous hemodynamics.

Regulation of hepatic blood flow: The hepatic arterial buffer response revisited

The interest in the liver dates back to ancient times when it was considered to be the seat of life processes. The liver is indeed essential to life, not only due to its complex functions in biosynthesis, metabolism and clearance, but also its dramatic role as the blood volume reservoir. Among parenchymal organs, blood flow to the liver is unique due to the dual supply from the portal vein and the hepatic artery. Knowledge of the mutual communication of both the hepatic artery and the portal vein is essential to understand hepatic physiology and pathophysiology. To distinguish the individual importance of each of these inflows in normal and abnormal states is still a challenging task and the subject of ongoing research. A central mechanism that controls and allows constancy of hepatic blood flow is the hepatic arterial buffer response. The current paper reviews the relevance of this intimate hepatic blood flow regulatory system in health and disease. We exclusively focus on the endogenous interrelationship between the hepatic arterial and portal venous inflow circuits in liver resection and transplantation, as well as inflammatory and chronic liver diseases. We do not consider the hepatic microvascular anatomy, as this has been the subject of another recent review.