title: Prolonged two-man basic life support may result in hypocarbia in the ventilating rescuer.
abstract: OBJECTIVE
  To determine whether the quality of expired air given during mouth-to-mouth ventilation differs between one- and two-person basic life support.
  
  
  METHODS
  15 young fit volunteers performed 15-min simulated resuscitation on a manikin. The oxygen and carbon dioxide concentration of their expired breath and the total ventilation was continuously monitored. Compression:ventilation ratios of 15:2 for one-person and 5:1 for two-person resuscitation were used.
  
  
  RESULTS
  In two-man resuscitation, where the rescuer who is ventilating the patient is not performing chest compressions, the oxygen content of the expired breath rises (P<0.01), and the carbon dioxide content falls (P<0.01). The carbon dioxide concentration declined gradually throughout the 15-min session. Most participants complained of light-headedness on completion of the two-man session. Total ventilation did not differ between the two methods (P=0.757, 95% CI=-0.329, 0.242).
  
  
  CONCLUSIONS
  Trainees in basic life support should be informed that symptoms of hypocarbia may occur in prolonged mouth-to-mouth ventilation, when acting in a two-man team. We would advise rescuers using these protocols to change places every 5 min to avoid these symptoms. These findings add further weight to the recommendations that all resuscitation should be carried out using 15:2 compression:ventilation ratio.
authors.affiliation: Royal Hospital for Sick Children, Yorkhill NHS Trust, Glasgow G3 8SJ, UK. gregor.walker@yorkhill.scot.nhs.uk
authors.forename: G M
authors.initials: GM
authors.lastname: Walker
authors.forename: R
authors.initials: R
authors.lastname: Liddle
mesh_terms: D000328:Adult; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis*; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D006801:Humans; D008348:Manikins; D010100:Oxygen / Q000032:analysis*; D013337:Students, Medical; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen