Vasopressin: Its current role in anesthetic practice

Therapeutic potential of vasopressin in the treatment of neurological disorders

Vasopressin (VP) is a nonapeptide made of nine amino acids synthesized by the hypothalamus and released by the pituitary gland. VP acts as a neurohormone, neuropeptide and neuromodulator and plays an important role in the regulation of water balance, osmolarity, blood pressure, body temperature, stress response, emotional challenges, etc. Traditionally VP is known to regulate the osmolarity and tonicity. VP and its receptors are widely expressed in the various region of the brain including cortex, hippocampus, basal forebrain, amygdala, etc. VP has been shown to modulate the behavior, stress response, circadian rhythm, cerebral blood flow, learning and memory, etc. The potential role of VP in the regulation of these neurological functions have suggested the therapeutic importance of VP and its analogues in the management of neurological disorders. Further, different VP analogues have been developed across the world with different pharmacotherapeutic potential. In the present work authors highlighted the therapeutic potential of VP and its analogues in the treatment and management of various neurological disorders.

Comparison of various vasopressin doses to epinephrine during cardiopulmonary resuscitation in asphyxiated neonatal piglets

BACKGROUND

Current neonatal resuscitation guidelines recommend epinephrine for cardiac arrest. Vasopressin might be an alternative during asphyxial cardiac arrest. We aimed to compare vasopressin and epinephrine on incidence and time to return of spontaneous circulation (ROSC) in asphyxiated newborn piglets.

DESIGN/METHODS

Newborn piglets (n = 8/group) were anesthetized, intubated, instrumented, and exposed to 30 min of normocapnic hypoxia, followed by asphyxia and asystolic cardiac arrest. Piglets were randomized to 0.2, 0.4, or 0.8IU/kg vasopressin, or 0.02 mg/kg epinephrine. Hemodynamic parameters were continuously measured.

RESULTS

Median (IQR) time to ROSC was 172(103-418)s, 157(100-413)s, 122(93-289)s, and 276(117-480)s for 0.2, 0.4, 0.8IU/kg vasopressin, and 0.02 mg/kg epinephrine groups, respectively (p = 0.59). The number of piglets that achieved ROSC was 6(75%), 6(75%), 7(88%), and 5(63%) for 0.2, 0.4, 0.8IU/kg vasopressin, and 0.02 mg/kg epinephrine, respectively (p = 0.94). The epinephrine group had a 60% (3/5) rate of post-ROSC survival compared to 83% (5/6), 83% (5/6), and 57% (4/7) in the 0.2, 0.4, and 0.8IU/kg vasopressin groups, respectively (p = 0.61).

CONCLUSION

Time to and incidence of ROSC were not different between all vasopressin dosages and epinephrine. However, non-significantly lower time to ROSC and higher post-ROSC survival in vasopressin groups warrant further investigation.

IMPACT

Time to and incidence of ROSC were not statistically different between all vasopressin dosages and epinephrine. Non-significantly lower time to ROSC and higher post-ROSC survival in vasopressin-treated piglets. Overall poorer hemodynamic recovery following ROSC in epinephrine piglets compared to vasopressin groups. Human neonatal clinical trials examining the efficacy of vasopressin during asphyxial cardiac arrest will begin recruitment soon.

Metabolism and Excretion of Therapeutic Peptides: Current Industry Practices, Perspectives, and Recommendations

Therapeutic peptides (TPeps) have expanded from the initial endogenous peptides to complex modified peptides through medicinal chemistry efforts for almost a century. Different from small molecules and large proteins, the diverse submodalities of TPeps have distinct structures and carry different absorption, distribution, metabolism, and excretion (ADME) properties. There is no distinct regulatory guidance for the industry on conducting ADME studies (what, how, and when) for TPeps. Therefore, the Peptide ADME Working Group sponsored by the Translational and ADME Sciences Leadership Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) was formed with the goal to develop a white paper focusing on metabolism and excretion studies to support discovery and development of TPeps. In this paper, the key learnings from an IQ industry survey and U.S. Food and Drug Administration/European Medicines Agency submission documents of TPeps approved between 2011 and 2022 are outlined in detail. In addition, a comprehensive assessment of in vitro and in vivo metabolism and excretion studies, mitigation strategies for TPep metabolism, analytical tools to conduct studies, regulatory status, and Metabolites in Safety Testing considerations are provided. Finally, an industry recommendation on conducting metabolism and excretion studies is proposed for regulatory filing of TPeps. SIGNIFICANCE STATEMENT: This white paper presents current industry practices for metabolism and excretion studies of therapeutic peptides based on an industry survey, regulatory submission documents, and expert opinions from the participants in the Peptide Absorption, Distribution, Metabolism, and Excretion Working Group of the International Consortium for Innovation and Quality in Pharmaceutical Development. The group also provides recommendations on the Metabolites in Safety Testing considerations and metabolism and excretion studies for regulatory filing of therapeutic peptides.

Vasopressin-induced hyponatremia in an adult normotensive trauma patient: A case report

BACKGROUND

Arginine vasopressin is a neuropeptide produced in the hypothalamus and released by the posterior pituitary gland. In addition to maintaining plasma osmolarity, under hypovolemic or hypotensive conditions, it helps maintain plasma volume through renal water reabsorption and increases systemic vascular tone. Its synthetic analogues are widely used in the intensive care unit as a continuous infusion, in addition to hospital floors as an intravenous or intranasal dose. A limited number of cases of hyponatremia in patients with septic or hemorrhagic shock have been reported previously with vasopressin. We report for the first time a normotensive patient who developed vasopressin-induced hyponatremia.

CASE SUMMARY

A 39-year-old man fell off a forklift and sustained an axial load injury to his cranium. He had no history of previous trauma. Examination was normal except for motor and sensory deficits. The Imagine test showed endplate fracture at C7 and acute traumatic disc at C7 with cortical degeneration. He underwent cervical discectomy and fusion, laminectomy, and posterior instrumented fusion. After intensive care unit admission post-surgery, he developed hyponatremia of 121-124 mEq/L post phenylephrine and vasopressin infusion to maintain blood pressure maintenance. He was evaluated for syndrome of inappropriate secretion of antidiuretic hormone, hypothyroid, adrenal-induced, or diuretic-induced hyponatremia. At the end of extensive evaluation for the underlying cause of hyponatremia, vasopressin was discontinued. He was also put on fluid restriction, given exogenous desmopressin, and a dextrose 5% in water infusion to prevent osmotic demyelination syndrome caused by sodium overcorrection which improved his sodium level to 135 mmol/L.

CONCLUSION

The presentation of vasopressin-induced hyponatremia is uncommon in normotensive patients, and the most difficult aspect of this condition is determining the underlying cause of hyponatremia. Our case illustrates that, considering the vast differential diagnosis of hyponatremia in hospitalized patients, both hospitalists and intensivists should be aware of this serious complication of vasopressin therapy.

Bolus Vasopressor Use for Air Medical Rapid Sequence Intubation: The Vasopressor Intravenous Push to Enhance Resuscitation Trial

BACKGROUND

Rapid sequence intubation (RSI) may compromise perfusion because of the use of sympatholytic medications as well as subsequent positive pressure ventilation. The use of bolus vasopressor agents may reverse hypotension and prevent arrest.

METHODS

This was a prospective, observational study enrolling air medical patients with critical peri-RSI hypotension (systolic blood pressure [SBP] < 90 mm Hg) to receive either arginine vasopressin (aVP), 2 U intravenously every 5 minutes, for trauma patients or phenylephrine (PE), 200 μg intravenously every 5 minutes, for nontrauma patients. The main outcome measures included an increase in SBP, a reversal of hypotension, and the occurrence of dysrhythmia or hypertension (SBP > 160 mm Hg) within 20 minutes of vasopressor administration.

RESULTS

A total of 523 patients (344 aVP and 179 PE) were enrolled over 2 years. An increase in SBP was observed in 326 aVP patients (95%), with reversal of hypotension in 272 patients (79%). An increase in SBP was observed in 171 PE patients (96%), with reversal of hypotension in 148 patients (83%). A low rate of rebound hypertension was observed for both aVP and PE patients.

CONCLUSION

Both aVP and PE appear to be safe and effective for treating critical hypotension in the peri-RSI period.

Hemodynamic dysfunction in neonatal sepsis

Cardiovascular disturbances are a frequent occurrence in neonatal sepsis. Preterm and term infants are particularly vulnerable due to the unique features of their cardiovascular function and reserve, compared to older children and adults. The clinical manifestations of neonatal sepsis are a product of the variable inflammatory pathways involved (warm vs. cold shock physiology), developmental state of the cardiovascular system, and hormonal responses. Targeted neonatal echocardiography has played an important role in advancing our knowledge, may help delineate specific hemodynamic phenotypes in real-time, and supports an individualized physiology-based management of sepsis-associated cardiovascular dysfunction. IMPACT: Cardiovascular dysfunction is a common sequela of sepsis. This review aims to highlight the pathophysiological mechanisms involved in hemodynamic disturbance in neonatal sepsis, provide insights from targeted neonatal echocardiography-based clinical studies, and suggest its potential incorporation in day-to-day management.

Pharmacological MRI with Simultaneous Measurement of Cerebral Perfusion and Blood-Cerebrospinal Fluid Barrier Function using Interleaved Echo-Time Arterial Spin Labelling

Pharmacological MRI (phMRI) studies seek to capture changes in brain haemodynamics in response to a drug. This provides a methodological platform for the evaluation of novel therapeutics, and when applied to disease states, may provide diagnostic or mechanistic information pertaining to common brain disorders such as dementia. Changes to brain perfusion and blood-cerebrospinal fluid barrier (BCSFB) function can be probed, non-invasively, by arterial spin labelling (ASL) and blood-cerebrospinal fluid barrier arterial spin labelling (BCSFB-ASL) MRI respectively. Here, we introduce a method for simultaneous recording of pharmacological perturbation of brain perfusion and BCSFB function using interleaved echo-time ASL, applied to the anesthetized mouse brain. Using this approach, we capture an exclusive decrease in BCSFB-mediated delivery of arterial blood water to ventricular CSF, following anti-diuretic hormone, vasopressin, administration. The commonly used vasodilatory agent, CO2, induced similar increases (~21%) in both cortical perfusion and the BCSFB-ASL signal. Furthermore, we present evidence that caffeine administration triggers a marked decrease in BCSFB-mediated labelled water delivery (41%), with no significant changes in cortical perfusion. Finally, we demonstrate a marked decrease in the functional response of the BCSFB to, vasopressin, in the aged vs adult brain. Together these data, the first of such kind, highlight the value of this translational approach to capture simultaneous and differential pharmacological modulation of vessel tone at the blood brain barrier and BCSFB and how this relationship may be modified in the ageing brain.

Validation of an integrative mathematical model of dehydration and rehydration in virtual humans

Water homeostasis is one of the body's most critical tasks. Physical challenges to the body, including exercise and surgery, almost always coordinate with some change in water handling reflecting the changing needs of the body. Vasopressin is the most important hormone that contributes to short‐term water homeostasis. By manipulating vascular tone and regulating water reabsorption in the collecting duct of the kidneys, vasopressin can mediate the retention or loss of fluids quickly. In this study, we validated HumMod, an integrative mathematical model of human physiology, against six different challenges to water homeostasis with special attention to the secretion of vasopressin and maintenance of electrolyte balance. The studies chosen were performed in normal men and women, and represent a broad spectrum of perturbations. HumMod successfully replicated the experimental results, remaining within 1 standard deviation of the experimental means in 138 of 161 measurements. Only three measurements lay outside of the second standard deviation. Observations were made on serum osmolarity, serum vasopressin concentration, serum sodium concentration, urine osmolarity, serum protein concentration, hematocrit, and cumulative water intake following dehydration. This validation suggests that HumMod can be used to understand water homeostasis under a variety of conditions.

Assessment of Blood Loss in Abdominal Myomectomy by Intramyometrial Vasopressin Administration Versus Conventional Tourniquet Application

INTRODUCTION

Myomectomy is an invasive surgical procedure. It can be associated with intraoperative and postoperative complications like excessive haemorrhage. There are various methods to control haemorrhage like pharmacological and as well as mechanical methods.

AIM

This study was taken to compare intraoperative blood loss following abdominal myomectomy after receiving intramyometrial vasopressin or tourniquet application and to estimate postoperative reduction in haemoglobin & haematocrit values.

MATERIALS AND METHODS

The study was a randomised single blinded parallel group study. Total 48 patients were included in this study according to inclusion and exclusion criteria. All patients were divided into two groups i.e. 'T' and 'V' group, 24 in each group. 'T' group received conventional tourniquet application and 'V' group received intramyometrial vasopressin administration. The analyses in this study were both sided and p<0.05 was considered significant statistically. The Software used were Statistica version 6 (Tulsa, Oklahoma: Stat Soft Inc., 2001) and Graph Pad Prism version 5 (San Diego, California: Graph Pad Software Inc., 2007).

RESULTS

The blood loss in the tourniquet group was significantly higher (p=<0.001). Postoperative haemoglobin and haematocrit were lower in tourniquet group than vasopressin group. There was significant fall in haemoglobin and haematocrit in postoperative period in both group (p=<0.001) but it was more in tourniquet group. Total five patients (three in tourniquet group and two in vasopressin group) had received one unit whole blood transfusion.

CONCLUSION

Intramyometrial vasopressin injection during myomectomy operation more effectively decreases the blood loss, need for blood transfusion and it causes less reduction in haemoglobin and haematocrit. Thereby it seems to be an effective method without having any risk of ischemic damage to the uterus.