The rescuer’s exhaled air contains approximately _____ oxygen and _____ carbon dioxide.
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Study objective: To compare the concentration of a rescuer's exhaled O2 and CO2 during mouth-to-mouth ventilation with or without chest compression. Show Design: Prospective repeated measures study. Simulated one- and two-rescuer cardiopulmonary resuscitation (CPR) was performed as recommended by the American Heart Association. Setting: University laboratory. Participants: Fifty-five healthcare professionals certified in basic and advanced cardiac life support volunteered as rescuers in this study. Measurements and results: Thirty-three volunteers performed one-rescuer CPR, and 22 volunteers performed two-rescuer CPR. Minute ventilation for both groups increased 50% to 130% during CPR (p < 0.05). During the performance of CPR, the concentration of exhaled O2 increased from 16.4 +/- 0.7% to 16.9 +/- 0.5% in the one-rescuer CPR group and from 16.5 +/- 0.9% to 17.8 +/- 0.6% in the two-rescuer CPR group (p < 0.05). The concentration of exhaled CO2 in the one-rescuer CPR group did not change significantly throughout the entire experiment, but decreased in the two-rescuer CPR group from a baseline measurement of 4.0 +/- 0.6% to 3.5 +/- 0.4% (p < 0.05). During CPR, the concentration of exhaled CO2 was 4.0 +/- 0.4% in the one-rescuer CPR group compared with 3.5 +/- 0.4% in the two-rescuer CPR group (p < 0.05). Conclusions: The gas given by mouth-to-mouth ventilation is a hypercarbic and hypoxic mixture compared with room air. Mouth-to-mouth ventilation is the only circumstance in which a hypercarbic and hypoxic gas is given as therapy. Further laboratory and clinical studies are necessary to determine the effect of mouth-to-mouth ventilation during CPR. SummaryRead the full fact sheet
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What percentage of oxygen do mouthBecause mouth-to-mouth ventilation gas contains only 17% oxygen, but 4% carbon dioxide, it is unknown whether 500-mL tidal volumes given during rescue breathing may result in insufficient oxygenation and inadequate carbon dioxide elimination.
How does CPR work if we exhale CO2?There is still plenty of oxygen to supply a victim with enough to keep things going. In addition, the additional carbon dioxide in the rescuer's breath will raise the victim's blood carb on dioxide levels, which will addd to the normal stimulus to start breathing on their own.
Do we give CO2 during CPR?During CPR, the concentration of exhaled CO2 was 4.0 +/- 0.4% in the one-rescuer CPR group compared with 3.5 +/- 0.4% in the two-rescuer CPR group (p < 0.05). Conclusions: The gas given by mouth-to-mouth ventilation is a hypercarbic and hypoxic mixture compared with room air.
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