# Hemodynamic rescue after blast injury: intravenous administration outperforms intramuscular vasopressin in a swine model

## TL;DR

In a swine model of blast injury and bleeding, intravenous terlipressin was more effective than intramuscular vasopressin in stabilizing blood pressure and improving outcomes.

## Contribution

Demonstrates that intravenous vasopressin analogues are more reliable than intramuscular administration in blast-associated hemorrhagic shock.

## Key findings

- IV terlipressin significantly increased systolic arterial pressure and vascular resistance compared to controls.
- IM vasopressin analogues failed to produce consistent hemodynamic stabilization due to unreliable absorption.
- IV terlipressin improved mixed venous oxygen saturation and urine output without worsening respiratory or metabolic variables.

## Abstract

Hemorrhage remains the leading preventable cause of trauma mortality. Blast trauma combines primary blast effects with complex secondary and tertiary injuries, precipitating profound hemodynamic instability and microcirculatory disruption. While intramuscular (IM) arginine vasopressin (AVP) stabilizes arterial pressure in isolated hemorrhagic shock, vasopressin’s efficacy in blast-associated hemorrhagic shock is unknown.

In a randomized, blinded study, 22 swine underwent femoral blast injury and controlled class II hemorrhage. Animals received IM AVP 40 U (two doses 60 min apart due to short half-life and transient effects; n = 5), IM terlipressin 2 mg (n = 5), intravenous (IV) terlipressin 2 mg (n = 5), or saline control (n = 7). All subjects received a 500 mL autologous whole blood transfusion and were observed for 120 min. The primary outcome was systolic arterial pressure (SAP). Secondary outcomes included systemic vascular resistance index (SVRI), cardiopulmonary and metabolic variables, and serum AVP to assess IM uptake.

IV terlipressin rapidly stabilized hemodynamics, increasing SAP (mean difference 24 mmHg, p = 0.01) and SVRI (mean difference 44593 dynes·s·cm⁻⁵·kg, p = 0.004) versus controls, and increased mixed venous oxygen saturation and urine output. Respiratory and metabolic variables were similar across groups. Neither IM AVP nor IM terlipressin generated a meaningful pressor response. IM AVP absorption was profoundly variable and did not reliably translate into hemodynamic stabilization; only one animal demonstrated both high systemic uptake and a sustained response.

In blast-associated hemorrhagic shock, IV terlipressin provided consistent hemodynamic stabilization, whereas IM vasopressin analogues were unreliable, highlighting a critical limitation of the IM route in blast pathophysiology.

Preclinicaltrials.eu, PCT ID: PCTE0000548, Registration date: 30 October 2024.