Chest Compression Synchronized Ventilation versus Intermitted Positive Pressure Ventilation during Cardiopulmonary Resuscitation in a Pig Model

BACKGROUND: Guidelines recommend mechanical ventilation with Intermitted Positive Pressure Ventilation (IPPV) during resuscitation. The influence of the novel ventilator mode Chest Compression Synchronized Ventilation (CCSV) on gas exchange and arterial blood pressure compared with IPPV was investigated in a pig model. METHODS: In 12 pigs (general anaesthesia/intubation) ventricular fibrillation was induced and continuous chest compressions were started after 3min. Pigs were mechanically ventilated in a cross-over setting with 5 ventilation periods of 4min each: Ventilation modes were during the first and last period IPPV (100% O(2), tidalvolumes = 7ml/kgKG, respiratoryrate = 10/min), during the 2nd, 3rd and 4th period CCSV (100% O(2)), a pressure-controlled and with each chest compression synchronized breathing pattern with three different presets in randomized order. Presets: CCSV(A): P(insp) = 60mbar, inspiratorytime = 205ms; CCSV(B): P(insp) = 60mbar, inspiratorytime = 265ms; CCSV(C): P(insp) = 45mbar, inspiratorytime = 265ms. Blood gas samples were drawn for each period, mean arterial (MAP) and centralvenous (CVP) blood pressures were continuously recorded. Results as median (25%/75%percentiles). RESULTS: Ventilation with each CCSV mode resulted in higher PaO(2) than IPPV: PaO(2): IPPV(first): 19.6(13.9/36.2)kPa, IPPV(last): 22.7(5.4/36.9)kPa (p = 0.77 vs IPPV(first)), CCSV(A): 48.9(29.0/58.2)kPa (p = 0.028 vs IPPV(first), p = 0.0001 vs IPPV(last)), CCSV(B): 54.0 (43.8/64.1) (p = 0.001 vs IPPV(first), p = 0.0001 vs IPPV(last)), CCSV(C): 46.0 (20.2/58.4) (p = 0.006 vs IPPV(first), p = 0.0001 vs IPPV(last)). Both the MAP and the difference MAP-CVP did not decrease during twelve minutes CPR with all three presets of CCSV and were higher than the pressures of the last IPPV period. CONCLUSIONS: All patterns of CCSV lead to a higher PaO(2) and avoid an arterial blood pressure drop during resuscitation compared to IPPV in this pig model of cardiac arrest.