Splanchnic haemodynamics after intravenous terlipressin in anaesthetised healthy pigs

Countering hemorrhagic shock due to duodenal variceal rupture with resuscitative endovascular balloon occlusion of the aorta

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has become an important option for managing life-threatening, traumatic or non-traumatic, arterial bleeding. The use of REBOA in variceal hemorrhagic shock, however, has rarely been reported. A 54-year-old man with untreated alcoholic liver cirrhosis presented with hematochezia and altered mental status. Contrast-enhanced computed tomography suggested ruptured duodenal varices. Since the patient had profound hypotension, we performed REBOA to temporize the hemorrhage. Immediately after balloon inflation, his blood pressure increased, allowing us to safely perform endoscopic variceal ligation. Our case indicates that REBOA is effective in controlling portal venous flow in acute gastrointestinal variceal hemorrhage.

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

The effects of terlipressin and direct portacaval shunting on liver hemodynamics following 80% hepatectomy in the pig

Liver failure is the major cause of death following liver resection. Post-resection portal venous pressure (PVP) predicts liver failure, is implicated in its pathogenesis, and when PVP is reduced, rates of liver dysfunction decrease. The aim of the present study was to characterize the hemodynamic, biochemical, and histological changes induced by 80% hepatectomy in non-cirrhotic pigs and determine if terlipressin or direct portacaval shunting can modulate these effects. Pigs were randomized (n=8/group) to undergo 80% hepatectomy alone (control); terlipressin (2 mg bolus + 0.5-1 mg/h) + 80% hepatectomy; or portacaval shunt (PCS) + 80% hepatectomy, and were maintained under terminal anesthesia for 8 h. The primary outcome was changed in PVP. Secondary outcomes included portal venous flow (PVF), hepatic arterial flow (HAF), and biochemical and histological markers of liver injury. Hepatectomy increased PVP (9.3 ± 0.4 mmHg pre-hepatectomy compared with 13.0 ± 0.8 mmHg post-hepatectomy, P<0.0001) and PVF/g liver (1.2 ± 0.2 compared with 6.0 ± 0.6 ml/min/g, P<0.0001) and decreased HAF (70.8 ± 5.0 compared with 41.8 ± 5.7 ml/min, P=0.002). Terlipressin and PCS reduced PVP (terlipressin = 10.4 ± 0.8 mmHg, P=0.046 and PCS = 8.3 ± 1.2 mmHg, P=0.025) and PVF (control = 869.0 ± 36.1 ml/min compared with terlipressin = 565.6 ± 25.7 ml/min, P<0.0001 and PCS = 488.4 ± 106.4 ml/min, P=0.002) compared with control. Treatment with terlipressin increased HAF (73.2 ± 11.3 ml/min) compared with control (40.3 ± 6.3 ml/min, P=0.026). The results of the present study suggest that terlipressin and PCS may have a role in the prevention and treatment of post-resection liver failure.

Effects of terlipressin on systemic, hepatic and renal hemodynamics in patients with cirrhosis

BACKGROUND AND AIM

Terlipressin has been shown to be effective in the management of hepatorenal syndrome. However, how terlipressin exerts its effect on the renal artery is unknown. The aim of the present study was to assess the effects of terlipressin on systemic, hepatic and renal hemodynamics in cirrhosis.

METHODS

Twenty-eight patients with cirrhosis and portal hypertension were studied. Systemic and hepatic hemodynamics, hepatic and renal arterial resistive indices and neurohumoral factors were measured prior to and 30 min after intravenous administration of 1 mg terlipressin (n = 19) or placebo (n = 9).

RESULTS

After terlipressin, there were significant increases in both mean arterial pressure (P < 0.001) and systemic vascular resistance (P < 0.001), whereas heart rate (P < 0.001) and cardiac output (P < 0.001) decreased significantly. There was a significant decrease in the hepatic venous pressure gradient (P < 0.001). Portal venous blood flow also decreased significantly (P < 0.001). The mean hepatic arterial velocity increased significantly (P < 0.001). Although there was a significant decrease in the hepatic arterial resistive index (0.72 +/- 0.08 to 0.69 +/- 0.08, P < 0.001) and renal arterial resistive index (0.74 +/- 0.07 to 0.68 +/- 0.07, P < 0.001), portal vascular resistance was unchanged (P = 0.231). Plasma renin activity decreased significantly (P < 0.005), and there was a significant correlation between this decline and the decrease in renal arterial resistive index (r = 0.764, P < 0.005). The effects of terlipressin on systemic, hepatic and renal hemodynamics were observed similarly in patients with and without ascites. Placebo caused no significant effects.

CONCLUSION

Terlipressin decreases hepatic and renal arterial resistance in patients with cirrhosis.

Vasopressin during cardiopulmonary resuscitation and different shock states: a review of the literature

Vasopressin administration may be a promising therapy in the management of various shock states. In laboratory models of cardiac arrest, vasopressin improved vital organ blood flow, cerebral oxygen delivery, the rate of return of spontaneous circulation, and neurological recovery compared with epinephrine (adrenaline). In a study of 1219 adult patients with cardiac arrest, the effects of vasopressin were similar to those of epinephrine in the management of ventricular fibrillation and pulseless electrical activity; however, vasopressin was superior to epinephrine in patients with asystole. Furthermore, vasopressin followed by epinephrine resulted in significantly higher rates of survival to hospital admission and hospital discharge. The current cardiopulmonary resuscitation guidelines recommend intravenous vasopressin 40 IU or epinephrine 1mg in adult patients refractory to electrical countershock. Several investigations have demonstrated that vasopressin can successfully stabilize hemodynamic variables in advanced vasodilatory shock. Use of vasopressin in vasodilatory shock should be guided by strict hemodynamic indications, such as hypotension despite norepinephrine (noradrenaline) dosages >0.5 mug/kg/min. Vasopressin must never be used as the sole vasopressor agent. In our institutional routine, a fixed vasopressin dosage of 0.067 IU/min (i.e. 100 IU/50 mL at 2 mL/h) is administered and mean arterial pressure is regulated by adjusting norepinephrine infusion. When norepinephrine dosages decrease to 0.2 microg/kg/min, vasopressin is withdrawn in small steps according to the response in mean arterial pressure. Vasopressin also improved short- and long-term survival in various porcine models of uncontrolled hemorrhagic shock. In the clinical setting, we observed positive effects of vasopressin in some patients with life-threatening hemorrhagic shock, which had no longer responded to adrenergic catecholamines and fluid resuscitation. Clinical employment of vasopressin during hemorrhagic shock is experimental at this point in time.

The effect of vasopressin and related compounds at V1a and V2 receptors in animal models relevant to human disease

Vasopressin, a neurohypophyseal peptide hormone, is the endogenous agonist at V1a, V1b and V2 receptors. The most important physiological function of vasopressin is the maintenance of water homeostasis through interaction with V2 receptors in the kidney. Vasopressin and related compounds are used in various clinical settings such as acute variceal bleeding associated with portal hypertension, septic shock, diabetes insipidus and coagulation disorders. The effect in the former two indications relates to the V1a receptor, and in the two latter indications the effect relates to the V2 receptor. Vasopressin and related compounds have demonstrated activity in animal models of portal hypertension, sepsis and septic shock, diabetes insipidus and coagulation disorders. The use of the compounds in animal models is reviewed. Generally, the effect of vasopressin and related compounds in animal models reflect the activity in the clinical setting, but in some cases important species differences exist.

The effects of vasopressin on systemic and splanchnic hemodynamics and metabolism in endotoxin shock

We compared the effects of vasopressin and norepinephrine on systemic and splanchnic circulation and metabolism in endotoxin shock in pigs. Twenty-one pigs were randomized to endotoxin shock (Escherichia coli endotoxin infusion) (n = 6), endotoxin and vasopressin (VASO; n = 6), endotoxin and norepinephrine (NE; n = 6), and controls (n = 3). Endotoxin infusion was increased to induce hypotension, after which vasopressin or norepinephrine was started to keep systemic mean arterial blood pressure >70 mm Hg. Regional blood flows and arterial and regional lactate concentrations were measured. Tonometers with microdialysis capillaries were inserted into the stomach, jejunum, and colon. Systemic mean arterial blood pressure >70 mm Hg was achieved in the VASO and NE groups. Vasopressin decreased cardiac output, superior mesenteric artery, and portal vein blood flow, whereas hepatic arterial blood flow increased. Arterial lactate concentration increased from 2.0 mM (1.6-2.1 mM) to 4.7 mM (4.7-4.9 mM) (P = 0.007). Systemic and mesenteric oxygen delivery and consumption decreased and oxygen extraction increased in the VASO group. Vasopressin increased mucosal-arterial PCO(2) gradients in all three locations, whereas luminal lactate release occurred only in the jejunum. Animals in the NE group remained stable. Vasopressin reversed hypotension but decreased systemic and gut blood flow. This was associated with hyperlactatemia, signs of visceral dysoxia, and jejunal luminal lactate release.

IMPLICATIONS

Although vasopressin induces vasoconstriction in visceral region, its effects on splanchnic circulation and metabolism during septic-endotoxin shock are still poorly characterized. We evaluated the metabolic and hemodynamic effects of vasopressin and norepinephrine within the splanchnic area in porcine endotoxin shock.

Management of acute variceal bleeding

Portal hypertension as a consequence of liver cirrhosis is responsible for its most common complications: ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, hepatic encephalopathy and the most important one--variceal hemorrhage. Variceal bleeding results in considerable morbidity and mortality. This review covers all areas of importance in the therapy of acute variceal hemorrhage--endoscopic and pharmacological treatment, transjugular intrahepatic portosystemic shunt, surgery and balloon tamponade. Indications and limitations of these therapeutic modalities are widely discussed.

Effects of pituitrin and triglycyl-lysine-vasopressin on hepatic oxygen partial pressure in portal hypertensive rats

AIM

To explore the different effects of pituitrin and triglycyl-lysine-vasopressin (tGLVP)on hepatic oxygen partial pressure (P_hO₂) while reducing the partial hypertension in portal hypertension rats.

METHODS

The model of biliary cirrhosis was induced by ligating the choledochus. Forty rats were divided into two groups randomly: pp group (n = 20)and tGLVP group(n = 20). PP and tGLVP were slowly infused into the rats via portal vein respectively. The portal vein pressure and the oxygen partial pressure were obtained at the moment before administration and 5, 10, 15, 25, 30 minutes after administration.

RESULTS

Portal venous pressure (PVP) was significantly lowered after infusion in two groups. There was no significant difference between the two groups (t = 0.39, P>0.05). P_hO₂ was significantly decreased in pp group after infusion (P<0.01), but not in tGLVP group (P<0.05).There was significant difference between the two groups in P_hO₂ after infusion (t = 9.19, P<0.01).

CONCLUSION

PP caused a significant decrease both in portal pressure and P_hO₂. PVP was decreased by tGLVP, but P_hO₂ was not decreased significantly. tGLVP is considered to be better than PP in treatment of acute variceal hemorrhage.

Management of vasodilatory shock: defining the role of arginine vasopressin

The rationale for an arginine vasopressin (argipressin) infusion was put forward after it was discovered that patients in shock states might have an endogenous arginine vasopressin deficiency. Subsequently, several investigations impressively demonstrated that arginine vasopressin can successfully stabilise haemodynamics even in advanced vasodilatory shock. We report on physiological and pharmacological aspects of arginine vasopressin, and summarise current clinical knowledge on employing a continuous arginine vasopressin infusion in critically ill patients with catecholamine-resistant vasodilatory shock of different aetiologies. In view of presented experimental evidence and current clinical experience, a continuous arginine vasopressin infusion of approximately 2 to approximately 6 IU/h can be considered as a supplemental strategy to vasopressor catecholamines in order to preserve cardiocirculatory homeostasis in patients with advanced vasodilatory shock. Because data on adverse effects are still limited, arginine vasopressin should be reserved for patients in whom adequate haemodynamic stabilisation cannot be achieved with conventional vasopressor therapy or who have obvious adverse effects of catecholamines that result in further significant haemodynamic deterioration. For the same reasons, arginine vasopressin should not be used as a single, alternative vasopressor agent instead of catecholamine vasopressors. Future prospective studies will be necessary to define the exact role of arginine vasopressin in the therapy of vasodilatory shock.

Splanchnic blood flow in low-flow states

IMPLICATIONS

Insufficient splanchnic blood flow in critically ill patients is the result of a multitude of different diseases, treatment modalities and their interplay, and is associated with increased morbidity and mortality. A combination of diminished and heterogeneous mesenteric blood flow, impaired or exhausted regulatory mechanisms and adverse drug effects may coexist with normal systemic hemodynamics.

Laboratory assessment of hepatic hemodynamics

Although the study of hepatic circulation is complicated by the dual blood supply and complex anatomy of the liver, many distinct methods are available to facilitate its study. Before embarking on an investigation of hepatic hemodynamics, the investigator must be familiar with the available methods and their applications. All methods have their own attributes and limitations. No one method is superior to the others, but, depending on the aspect of hepatic hemodynamics to be investigated, a particular methodology may yield distinct advantages.