Experimental blunt chest trauma – cardiorespiratory effects of different mechanical ventilation strategies with high positive end-expiratory pressure: a randomized controlled studyReportar como inadecuado




Experimental blunt chest trauma – cardiorespiratory effects of different mechanical ventilation strategies with high positive end-expiratory pressure: a randomized controlled study - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

BMC Anesthesiology

, 16:3

First Online: 12 January 2016Received: 28 May 2015Accepted: 09 December 2015

Abstract

BackgroundUncertainty persists regarding the optimal ventilatory strategy in trauma patients developing acute respiratory distress syndrome ARDS. This work aims to assess the effects of two mechanical ventilation strategies with high positive end-expiratory pressure PEEP in experimental ARDS following blunt chest trauma.

MethodsTwenty-six juvenile pigs were anesthetized, tracheotomized and mechanically ventilated. A contusion was applied to the right chest using a bolt-shot device. Ninety minutes after contusion, animals were randomized to two different ventilation modes, applied for 24 h: Twelve pigs received conventional pressure-controlled ventilation with moderately low tidal volumes VT, 8 ml-kg and empirically chosen high external PEEP 16cmH2O and are referred to as the HP-CMV-group. The other group n = 14 underwent high-frequency inverse-ratio pressure-controlled ventilation HFPPV involving respiratory rate of 65breaths · min, inspiratory-to-expiratory-ratio 2:1, development of intrinsic PEEP and recruitment maneuvers, compatible with the rationale of the Open Lung Concept. Hemodynamics, gas exchange and respiratory mechanics were monitored during 24 h. Computed tomography and histology were analyzed in subgroups.

ResultsComparing changes which occurred from randomization 90 min after chest trauma over the 24-h treatment period, groups differed statistically significantly all P values for group effect <0.001, General Linear Model analysis for the following parameters values are mean ± SD for randomization vs. 24-h: PaO2 100 % O2 HFPPV 186 ± 82 vs. 450 ± 59 mmHg; HP-CMV 249 ± 73 vs. 243 ± 81 mmHg, venous admixture HFPPV 34 ± 9.8 vs. 11.2 ± 3.7 %; HP-CMV 33.9 ± 10.5 vs. 21.8 ± 7.2 %, PaCO2 HFPPV 46.9 ± 6.8 vs. 33.1 ± 2.4 mmHg; HP-CMV 46.3 ± 11.9 vs. 59.7 ± 18.3 mmHg and normally aerated lung mass HFPPV 42.8 ± 11.8 vs. 74.6 ± 10.0 %; HP-CMV 40.7 ± 8.6 vs. 53.4 ± 11.6 %. Improvements occurring after recruitment in the HFPPV-group persisted throughout the study. Peak airway pressure and VT did not differ significantly. HFPPV animals had lower atelectasis and inflammation scores in gravity-dependent lung areas.

ConclusionsIn this model of ARDS following unilateral blunt chest trauma, HFPPV ventilation improved respiratory function and fulfilled relevant ventilation endpoints for trauma patients, i.e. restoration of oxygenation and lung aeration while avoiding hypercapnia and respiratory acidosis.

KeywordsPulmonary contusion Blunt chest trauma Acute respiratory distress syndrome Mechanical ventilation Positive end-expiratory pressure Hypercapnia Computed tomography Abbreviations\ \overset{\bullet }{V}C{O} 2 \CO2-production

ARDSacute respiratory distress syndrome

DO2Oxygen delivery

FIO2fraction of inspired oxygen

HFPPVhigh-frequency inverse-ratio pressure-controlled ventilation

HP-CMVconventional mechanical ventilation with moderately low VT and high PEEPext

PCVpressure-controlled ventilation

PEEPpositive end-expiratory pressure

PEEPextexternal PEEP

PEEPintintrinsic PEEP

PEEPtottotal PEEP

Phighinflating pressure

QVA-QTvenous admixture

VDdead-space

VO2oxygen consumption

VTtidal volume

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