• Nicolas Segal, Jennifer Rees, Victor A Convertino, Anja Metzger, Daniel Zarama, Leida Voulgaropoulos, Scott H McKnite, Demetris Yannopoulos, Wanchun Tang, Eric Vicaut, and Keith Lurie.
• Department of Emergency Medicine, University of Minnesota Medical Center, Minneapolis, MN, USA.
• Resuscitation. 2011 Dec 1;82 Suppl 2:S16-22.

Aim Of StudyIntrathoracic pressure regulation (IPR) has been used to treat hypotension and states of hypoperfusion by providing positive pressure ventilation during inspiration followed by augmentation of negative intrathoracic pressure during expiration. This therapy augments cardiac output and lowers intracranial pressure, thereby providing greater circulation to the heart and brain. The effects of IPR on microcirculation remain unknown.MethodsUsing a hemorrhagic model, hemodynamics and sublingual microcirculation were evaluated after a 55% blood loss over a 30 min timeframe in 10 female farm pigs (30 kg) previously anesthetized with isoflurane.ResultsAfter hemorrhage the mean arterial pressure was 27 ± 4 mm Hg. Blood cell velocity, the key indicator of microcirculation, was significantly reduced after the bleed from 1033 ± 175 μm/s pre-bleed to 147 ± 60 μm/s (p < 0.0001). Application of an IPR device reduced airway pressure during expiration to -9 mm Hg after each positive pressure breath (10 mL/kg, 10 breaths/min) and resulted in a rapid increase in systemic hemodynamics and microcirculation. During IPR treatment, average mean arterial pressure increased by 59% to 43 ± 6 mm Hg (p = 0.002) and blood cell velocity increased by 344% to 506 ± 99 μm/s (p = 0.001).ConclusionIn this animal model, we observed that microcirculation and systemic blood pressures are correlated and may be significantly improved by using IPR therapy.Copyright © 2011 Elsevier B.V. All rights reserved.

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