Two-rescuer CPR results in hyperventilation in the ventilating rescuer.
The "Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care--International Consensus on Science" recommend a tidal ventilation volume of 10 ml/kg body-weight without the use of supplemental oxygen during two-rescuer adult cardiopulmonary resuscitation (CPR). This relates to a ventilation volume of about 6.4 l/min. Additionally, the first aid provider ventilating the victim will breathe for him/herself during the external chest compression period adding another 3.2 l/min of ventilation. Finally, a deep breath is recommended before each ventilation to increase the end-expiratory oxygen concentration of the air exhaled. To investigate the effects of these recommendations, 20 healthy volunteers were asked to perform two-rescuer CPR in a lung model connected to a BLS-manikin. End-tidal carbon dioxide, oxygen saturation, and heart rate were recorded continuously. Capillary blood gas samples were collected and non-invasive blood pressure was recorded prior to the start of external chest compressions and immediately after the end of each measurement period. Furthermore, hyperventilation related symptoms reported by the volunteers were also recorded. The data reveal a significant decrease in capillary and end-tidal carbon dioxide pressure in the volunteers (P < 0.001). Additionally, in 75% of test persons multiple hyperventilation associated symptoms occurred. Ventilation during two-rescuer CPR performed according to the Guidelines 2000 may cause injury to the health of first aid providers. To minimize hyperventilation, both rescuers should exchange their positions at intervals of 3-5 min. These data challenge the recommendation to take a deep breath prior to each ventilation.