Ventilation During Cardiopulmonary Resuscitation: What Have We Learned From Models?

The optimization of ventilation during cardiopulmonary resuscitation (CPR) is a broad field of research. Recent physiological observations in this field challenge the current understanding of respiratory and circulatory interactions. Thanks to different models available (bench, animal, human), the understanding of physiological phenomena occurring during CPR has progressed. In this review, we describe the clinical observations that have led to the emerging concept of lung volume reduction and associated thoracic airway closure. We summarize the clinical and animal observations supporting these concepts. We then discuss the different contributions of bench, animal, and human models to the understanding of airway closure and their impact on intrathoracic pressure, airway closure, and hemodynamics generated by chest compression. The limitation of airway pressure and ventilation, resulting from airway closure reproducible in models, may play a major role in ventilation and gas exchange impairment observed during prolonged resuscitation.