No assisted ventilation cardiopulmonary resuscitation and 24-hour neurological outcomes in a porcine model of cardiac arrest

Division of Cardiology, University of Minnesota, Minneapolis, MN, USA.
Critical care medicine (Impact Factor: 6.31). 09/2009; 38(1):254-60. DOI: 10.1097/CCM.0b013e3181b42f6c
Source: PubMed


To evaluate the effect of no assisted ventilation cardiopulmonary resuscitation on neurologically intact survival compared with ten positive pressure ventilations/minute cardiopulmonary resuscitation in a pig model of cardiac arrest.
Prospective randomized animal study.
Animal laboratory.
Sixteen female intubated pigs (25.2 +/- 2.1 kg) anesthetized with propofol.
: fter 8 mins of untreated ventricular fibrillation, the intubated animals were randomized to 8 mins of continuous chest compressions (100/min) and either no assisted ventilation (n = 9) or 10 positive pressure ventilations/min (Smart Resuscitator Bag with 100% O2 flow at 10 L/min) (n = 7). The primary end point, neurologically intact 24-hr survival, was evaluated using a pig cerebral performance category score by a veterinarian blinded to the cardiopulmonary resuscitation method. MEASUREMENTS, AND MAIN RESULTS: During cardiopulmonary resuscitation, aortic and coronary perfusion pressure were similar between groups but cerebral perfusion pressure was significantly higher in the positive pressure ventilation group (33 +/- 15 vs. 14 +/- 14, p = .04). After 7.5 mins of cardiopulmonary resuscitation, arterial pO2 (mm Hg) and mixed venous O2 saturation (%) were significantly higher in the positive pressure ventilation compared with the no assisted ventilation group (117 +/- 29 and 41 +/- 21 vs. 40 +/- 24 and 10.8 +/- 7; p = .01 for both). Paco2 was significantly lower in the positive pressure ventilation group (48 +/- 10 vs. 77 +/- 26, p = .01). After 24 hrs, four of nine no assisted ventilation pigs were alive with a mean cerebral performance category score of 3 +/- 0 vs. five of seven alive and neurologically intact positive pressure ventilation pigs with a cerebral performance category score of 1 +/- 0.3 (p < .001 for cerebral performance category score).
No assisted ventilation cardiopulmonary resuscitation results in profound hypoxemia, respiratory acidosis, and significantly worse 24-hr neurologic outcomes compared with positive pressure ventilation cardiopulmonary resuscitation in pigs.

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Available from: Demetris Yannopoulos
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    • "Many former studies discussed the necessity of ventilation during CPR, but the outcomes were inconsistent. Ewy GA et al. demonstrated that neurological outcome was improved by continuous compressions [15], but Yannopoulos and colleagues demonstrated that when there was no assisted ventilation during CPR, 24 h neurological outcome was significantly worse compared to those with positive pressure ventilation simultaneous with CPR in pigs [16]. The main concern of this problem is whether abolishing ventilation could still maintain sufficient gas exchange during CPR. "
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    ABSTRACT: The use of mechanical cardiopulmonary resuscitation (CPR) has great potential for the clinical setting. The purpose of present study is to compare the hemodynamics and ventilation during and after the load-distributing band CPR, versus the manual CPR in a porcine model of prolonged cardiac arrest, and to investigate the influence of rescue breathing in different CPR protocols. Sixty-four male pigs (n = 16/group), weighing 30 ± 2 kg, were induced ventricular fibrillation and randomized into four resuscitation groups: continuous load-distributing band CPR without rescue ventilation (C-CPR), load-distributing band 30:2 CPR (A-CPR), load-distributing band CPR with continuous rescue breathing (10/min) (V-CPR) or manual 30:2 CPR (M-CPR). Respiratory variables and hemodynamics were recorded continuously; blood gas was analyzed. Tidal volume produced by compressions in the A-, C- and V-CPR groups were significantly higher compared with the M-CPR group (all p < 0.05). Coronary perfusion pressure of the V-CPR group was significantly lower than the C-CPR group (p < 0.01), but higher than the M-CPR group. The increasing of lung dead space after restoration of spontaneous circulation was significantly greater in the M-CPR group compared with the A-, C- and V-CPR groups (p < 0.01). Blood pH gradually decreased and was lower in the M-CPR group than that in the A-, C- and V-CPR groups (p < 0.01). PaO2 of the A-, C- and V-CPR groups were significantly higher and PaCO2 were significantly lower compared with the M-CPR (both p < 0.05). Cerebral performance categories were better in the A-, C- and V-CPR groups compared with the M-CPR group (p < 0.0001). The load-distributing band CPR significantly improved respiratory parameters during resuscitation by augmenting passive ventilation, and significantly improved coronary perfusion pressure. The volume of ventilation produced by the load-distributing band CPR was adequate to maintain sufficient gas exchange independent of rescue breathing.
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    • "The importance of ventilations in cardiac arrests lasting more than 3-4 minutes is more controversial, as two recent studies in a porcine models reported contradictory results [22,23]. "
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    ABSTRACT: Out-of-hospital cardiac arrest has a low survival rate to hospital discharge. Recent studies compared a simplified form of CPR, based on chest compression alone versus standard CPR including ventilation. We performed systematic review and meta-analysis of randomized controlled trials, focusing on survival at hospital discharge. We extensively searched the published literature on out-of hospital CPR for non traumatic cardiac arrest in different databases. We identified only three randomized trials on this topic, including witnessed and not-witnessed cardiac arrests. When pooling them together with a meta-analytic approach, we found that there is already clinical and statistical evidence to support the superiority of the compression-only CPR in terms of survival at hospital discharge, as 211/1842 (11.5%) patients in the chest compression alone group versus 178/1895 (9.4%) in the standard CPR group were alive at hospital discharge: odds ratio from both Peto and DerSimonian-Laird methods =0.80 (95% confidence interval 0.65-0.99), p for effect =0.04, p for heterogeneity =0.69, inconsistency =0%). Available evidence strongly support the superiority of bystander compression-only CPR. Reasons for the best efficacy of chest compression-only CPR include a better willingness to start CPR by bystanders, the low quality of mouth-to-mouth ventilation and a detrimental effect of too long interruptions of chest compressions during ventilation. Based on our findings, compression-only CPR should be recommended as the preferred CPR technique performed by untrained bystander.
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