在长时间心脏骤停的实验模型中，持续按压期间或按照30:2的按压与通气比进行通气，会产生相似的动脉血氧和二氧化碳水平。
Ventilation during continuous compressions or at 30:2 compression-to-ventilation ratio results in similar arterial oxygen and carbon dioxide levels in an experimental model of prolonged cardiac arrest.
作者信息
Kopra Jukka, Litonius Erik, Pekkarinen Pirkka T, Laitinen Merja, Heinonen Juho A, Fontanelli Luca, Mäkiaho Tomi P, Skrifvars Markus B
机构信息
Department of Emergency Care and Services, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
Division of Anaesthesiology, Department of Anaesthesiology, Intensive Care and Pain Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
出版信息
Intensive Care Med Exp. 2023 Jan 6;11(1):3. doi: 10.1186/s40635-022-00485-0.
BACKGROUND
In refractory out-of-hospital cardiac arrest, transportation to hospital with continuous chest compressions (CCC) from a chest compression device and ventilation with 100% oxygen through an advanced airway is common practice. Despite this, many patients are hypoxic and hypercapnic on arrival, possibly related to suboptimal ventilation due to the counterpressure caused by the CCC. We hypothesized that a compression/ventilation ratio of 30:2 would provide better ventilation and gas exchange compared to asynchronous CCC during prolonged experimental cardiopulmonary resuscitation (CPR).
METHODS
We randomized 30 anaesthetized domestic swine (weight approximately 50 kg) with electrically induced ventricular fibrillation to the CCC or 30:2 group and bag-valve ventilation with a fraction of inspired oxygen (FiO) of 100%. We started CPR after a 5-min no-flow period and continued until 40 min from the induction of ventricular fibrillation. Chest compressions were performed with a Stryker Medical LUCAS® 2 mechanical chest compression device. We collected arterial blood gas samples every 5 min during the CPR, measured ventilation distribution during the CPR using electrical impedance tomography (EIT) and analysed post-mortem computed tomography (CT) scans for differences in lung aeration status.
RESULTS
The median (interquartile range [IQR]) partial pressure of oxygen (PaO) at 30 min was 110 (52-117) mmHg for the 30:2 group and 70 (40-171) mmHg for the CCC group. The median (IQR) partial pressure of carbon dioxide (PaCO) at 30 min was 70 (45-85) mmHg for the 30:2 group and 68 (42-84) mmHg for the CCC group. No statistically significant differences between the groups in PaO (p = 0.40), PaCO (p = 0.79), lactate (p = 0.37), mean arterial pressure (MAP) (p = 0.47) or EtCO (p = 0.19) analysed with a linear mixed model were found. We found a deteriorating trend in PaO, EtCO and MAP and rising PaCO and lactate levels through the intervention. There were no differences between the groups in the distribution of ventilation in the EIT data or the post-mortem CT findings.
CONCLUSIONS
The 30:2 and CCC protocols resulted in similar gas exchange and lung pathology in an experimental prolonged mechanical CPR model.
背景
在难治性院外心脏骤停中，使用胸部按压装置进行持续胸外按压（CCC）并通过高级气道给予100%氧气进行通气后转运至医院是常见做法。尽管如此，许多患者在到达时仍存在低氧血症和高碳酸血症，这可能与CCC产生的反压导致通气不理想有关。我们假设在延长的实验性心肺复苏（CPR）过程中，30:2的按压/通气比与异步CCC相比能提供更好的通气和气体交换。
方法
我们将30只麻醉的家猪（体重约50 kg）随机分为CCC组或30:2组，这些家猪因电诱导心室颤动而接受100%的吸入氧分数（FiO）的球囊面罩通气。在5分钟的无血流期后开始CPR，并持续至心室颤动诱导后40分钟。使用史赛克医疗LUCAS® 2机械胸外按压装置进行胸外按压。在CPR期间每5分钟采集动脉血气样本，使用电阻抗断层扫描（EIT）测量CPR期间的通气分布，并分析尸检计算机断层扫描（CT）扫描结果以观察肺通气状态的差异。
结果
30:2组在30分钟时氧分压（PaO）的中位数（四分位间距[IQR]）为110（52 - 117）mmHg，CCC组为70（40 - 171）mmHg。30:2组在30分钟时二氧化碳分压（PaCO）的中位数（IQR）为70（45 - 85）mmHg，CCC组为68（42 - 84）mmHg。使用线性混合模型分析发现，两组在PaO（p = 0.40）、PaCO（p = 0.79）、乳酸（p = 0.37）、平均动脉压（MAP）（p = 0.47）或呼气末二氧化碳（EtCO）（p = 0.19）方面无统计学显著差异。我们发现通过干预，PaO、EtCO和MAP呈恶化趋势，而PaCO和乳酸水平升高。两组在EIT数据中的通气分布或尸检CT结果方面无差异。
结论
在实验性延长机械CPR模型中，30:2方案和CCC方案导致相似的气体交换和肺部病理变化。
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