Two-rescuer CPR results in hyperventilation in the ventilating rescuer

Arterial blood gases during basic life support of human cardiac arrest victims

BACKGROUND

Ventilation with tidal volumes sufficient to raise the victim's chest is an integral part of guidelines for lay-rescuer basic life support, but optimal tidal volume, frequency and ratio to chest compressions are not known.

METHODS

Adults with non-traumatic, out-of-hospital cardiac arrest, who were not successfully resuscitated following advanced life support by the staff of a physician-manned ambulance, were included. Advanced life support comprised tracheal intubation and mechanical ventilation with tidal volume of 700 ml and 100% oxygen, 12 times per min. An arterial blood sample was drawn at the end of the resuscitation attempt and analysed on the scene. After the victim was declared dead, basic life support was initiated with chest compressions and mouth-to-mask or mouth-to-tracheal tube ventilation (15:2), with volumes sufficient to make the chest rise. The tracheal tube was equipped with an impedance valve to avoid passive ventilation secondary to chest compressions. Arterial blood samples were drawn after 7-8 min of basic life support and analysed on the scene.

RESULTS

Six men and two women, median (range) age 72 (32-86) years, were included in the study. Four of these received mouth-to-mask ventilation and four mouth-to-tracheal tube ventilation. Mean (S.D.) arterial blood carbon dioxide and oxygen tension during advanced life support were 6.4 (1.4)kPa and 22 (15)kPa, respectively. Similar values during basic life support were 9.6 (1.9)kPa and 8.5 (1.6)kPa, respectively, with no differences between the ventilation methods.

CONCLUSION

Ventilation during basic life support performed according to international guidelines (2000) resulted in arterial hypercapnia and hypoxia.

Basic Life Support Ventilation in Mountain Rescue

Cardiopulmonary resuscitation in the mountains usually has to be performed under difficult and hostile circumstances and sometimes for extended periods of time. Therefore, mountain rescuers should have the ability and the appropriate equipment to perform prolonged, efficient, and safe ventilation. Members of the International Commission for Mountain Emergency Medicine (ICAR MEDCOM) discussed the results of a literature review, focusing on the advantages and disadvantages of common ventilation techniques in basic life support and their training methods with specific respect to use in mountain rescue, and recommendations were proposed. Bystanders fear the potential risk of infection and lack the willingness to perform mouth-to-mouth ventilation, though the risk of infection is low. Mouth-to-mouth ventilation remains the standard technique for bystander ventilation and, in the absence of a barrier device, bystanders should not hesitate to ventilate a patient by this technique. For mountain rescue teams, we encourage the use of a barrier device for artificial ventilation. Mouth-to-mask ventilation devices are most likely to fulfill the requirements of being safe, simple, and efficient in the hands of a basic-trained rescuer. The use of a mouth-to-mask ventilation device is recommended for out-of-hospital ventilation in the mountains and should be part of the mountain rescuer's standard equipment. Bag-valve-mask ventilation is efficient, if performed by well-trained rescuers, but it leads to a low ventilation quality in the hands of a less experienced rescuer. It should be emphasized that regular training every 6 to 12 months is necessary to perform proper ventilation.