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.


CONCLUSIONS
Ventilation during basic life support performed according to international guidelines (2000) resulted in arterial hypercapnia and hypoxia.
Institute for Experimental Medical Research and Department of Anaesthesiology, Ulleval University Hospital, Kirkeveien 166, N-0407 Oslo, Norway. morten.pytte@medisin.uio.no
Morten
M
Pytte
Elizabeth
E
Dorph
Kjetil
K
Sunde
Jo
J
Kramer-Johansen
Lars
L
Wik
Petter A
PA
Steen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004632:Emergency Medical Services; D005260:Female; D006323:Heart Arrest / Q000628:therapy*; D006801:Humans; D007442:Intubation, Intratracheal; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D013990:Tidal Volume / Q000502:physiology
D002245:Carbon Dioxide; D010100:Oxygen