Recommendations for Ventilation During Cardiopulmonary Resuscitation: Time for Change?

Melker RJ Critical Care Medicine 1985 Vol 11 Pages 882-883 OF HISTORICAL INTEREST

The author discusses the rationale for ventilation changes since adopted in the BCLS-CPR standards. Using a mechanical model of the tracheobronchial tree and upper GI tract, the device used, allows lung-thorax compliance (CLT), airway resistance (RAW), and lower esophageal sphincter (LES) pressure to be varied in studying the distribution of gas between the lungs and stomach. Previous standards for two-person CPR called for 0.8-1.2 L breaths interposed within .5 secs after every fifth chest compression. During one-person CPR, incremental 2.0 L tidal volumes were recommended. With the single-rescuer pattern, half of the second breath (0.94 L) enters the stomach even when CLT, RAW and LES are normal. With poor CLT, 0.8 L enters the lungs and 1.85 L enters the stomach over two breaths. During two-rescuer CPR, no volume enters the stomach when CLT, RAW and LES pressure is normal and tidal volume is not greater than 0.85 L. In a related swine study, 30% decreases in CLT, and LES pressure reductions from 26 to 4 mmHg during 15 minutes of ventricular fibrillation, were documented. This suggests an increasing likelihood of gastric insufflation and hypoventilation during continuing cardiac arrest. As the findings suggest that ventilation is ineffective with techniques being used, the author recommended a longer inspiratory time with elimination of incremental breaths during one-rescuer CPR. A single slow breath would replace the two incremental breaths, and during two-person CPR, a pause of 1.0-1.5 secs would allow for ventilation after every fifth compression. As gastric insufflation is a frequent and dangerous complication of ventilation with an unprotected airway, the author further recommended the teaching of the Sellick Maneuver (cricoid pressure) to prevent regurgitation and gastric insufflation during positive-pressure breathing, as well as further study of asynchronous-ventilation CPR (ASV-CPR) as an alternative BCLS-CPR method.