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Moderate and prolonged hypercapnic acidosis may protect against ventilator-induced diaphragmatic dysfunction in healthy piglet: an in vivo study

Boris Jung1, Mustapha Sebbane2, Charlotte Le Goff1, Nans Rossel1, Gerald Chanques1, Emmanuel Futier3, Jean-Michel Constantin3, Stefan Matecki1 and Samir Jaber1*

Author Affiliations

1 Intensive Care Unit, Department of Anaesthesia and Critical Care, Saint Eloi Teaching Hospital and Institut National de la Santé et de la Recherche Médicale Unit 1046 (INSERM U-1046), Université Montpellier 1, 34295 Montpellier, France

2 Department of Emergency Medicine, Lapeyronie Teaching Hospital, Université Montpellier 1, 34295 Montpellier, France

3 Department of Anesthesiology and Critical Care, Clermont Ferrand University Hospital F-63000, France

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Critical Care 2013, 17:R15  doi:10.1186/cc12486


See related commentary by Akca and Bautista, http://ccforum.com/content/17/2/129

Published: 24 January 2013

Abstract

Introduction

Protective ventilation by using limited airway pressures and ventilation may result in moderate and prolonged hypercapnic acidosis, as often observed in critically ill patients. Because allowing moderate and prolonged hypercapnia may be considered protective measure for the lungs, we hypothesized that moderate and prolonged hypercapnic acidosis may protect the diaphragm against ventilator-induced diaphragmatic dysfunction (VIDD). The aim of our study was to evaluate the effects of moderate and prolonged (72 hours of mechanical ventilation) hypercapnic acidosis on in vivo diaphragmatic function.

Methods

Two groups of anesthetized piglets were ventilated during a 72-hour period. Piglets were assigned to the Normocapnia group (n = 6), ventilated in normocapnia, or to the Hypercapnia group (n = 6), ventilated with moderate hypercapnic acidosis (PaCO2 from 55 to 70 mm Hg) during the 72-hour period of the study. Every 12 hours, we measured transdiaphragmatic pressure (Pdi) after bilateral, supramaximal transjugular stimulation of the two phrenic nerves to assess in vivo diaphragmatic contractile force. Pressure/frequency curves were drawn after stimulation from 20 to 120 Hz of the phrenic nerves. The protocol was approved by our institutional animal-care committee.

Results

Moderate and prolonged hypercapnic acidosis was well tolerated during the study period. The baseline pressure/frequency curves of the two groups were not significantly different (Pdi at 20 Hz, 32.7 ± 8.7 cm H2O, versus 34.4 ± 8.4 cm H2O; and at 120 Hz, 56.8 ± 8.7 cm H2O versus 60.8 ± 5.7 cm H2O, for Normocapnia and Hypercapnia groups, respectively). After 72 hours of ventilation, Pdi decreased by 25% of its baseline value in the Normocapnia group, whereas Pdi did not decrease in the Hypercapnia group.

Conclusions

Moderate and prolonged hypercapnic acidosis limited the occurrence of VIDD during controlled mechanical ventilation in a healthy piglet model. Consequences of moderate and prolonged hypercapnic acidosis should be better explored with further studies before being tested on patients.