Use of an inspiratory impedance threshold valve during chest compressions without assisted ventilation may result in hypoxaemia.

Introduction: Although the concept of intermittent airway occlusion with the inspiratory impedance threshold valve (ITV) is a well-recognised strategy for improving efficiency of cardiopulmonary resuscitation (CPR), little is known about possible pulmonary side effects.

Methods: After a baseline chest CT-scan, 24 pigs with beating hearts undergoing apnoeic oxygenation received an injection of a contrast medium and were then assigned randomly to either active compression-decompression CPR with ITV (ACD ITV CPR), ACD CPR alone, or standard-CPR with ITV (standard-ITV CPR), or standard-CPR alone. After a maximum of 5 min of chest compressions or if oxygen saturation dropped below 70%, the experiment was stopped, haemodynamic variables and blood gas values were measured, and another CT-scan was performed; all animals underwent a 30 min recovery-period and a third subsequent CT-scan.

An observational study of vasopressin infusion during uncontrolled haemorrhagic shock in a porcine trauma model: Effects on bowel function.

The effects of vasopressin on the gut in a porcine uncontrolled haemorrhagic shock model are described. In eight anaesthetised pigs, a liver laceration was performed; when haemorrhagic shock was decompensated, all animals received 0.4 IU/kg vasopressin, followed by 0.

Detrimental hemodynamic effects of assisted ventilation in hemorrhagic states.

Objective: Our goal was to demonstrate explicitly that lower-frequency positive-pressure ventilation not only preserves adequate oxygenation and acid-base status in hemorrhagic states, but also that "normal" or higher respiratory rates significantly compromise hemodynamics, even with moderate degrees of hemorrhage.

Design And Subjects: Eight intubated pigs (ventilated with 12 mL/kg tidal volume, 28% FIO2, respiratory rate = 12 breaths/min) were hemorrhaged to <65 mm Hg of systolic blood pressure. Respiratory rates were then sequentially changed every 10 mins to 6, 20, 30, and 6 breaths/min.

Treatment of hypotension in pigs with an inspiratory impedance threshold device: a feasibility study.

Objective: An inspiratory impedance threshold device was evaluated in spontaneously breathing animals with hypotension to determine whether it could help improve systemic arterial pressures when fluid replacement was not immediately available.

Design: Prospective, randomized.

Setting: Animal laboratory.