Abstract P162: Mouth-to-nose Breathing Provides more Effective Ventilation than Mouth-to-mouth Breathing
Introduction: Effectiveness of mouth-to-mouth breathing (MMB) during standard CPR performed by laypersons has recently been challenged because of the lack of additional benefit compared with chest compressions alone.
Hypothesis: We hypothesized that mouth-to-nose breathing (MNB) would be more effective ventilation than MMB during CPR.
Methods: The study was done in non-paralyzed, apneic, adult subjects under general anesthesia (n=11). An experienced anesthesiologists provided MMB and MNB in a random order (MMB>MNB>MMB or MNB>MMB>MNB) with head in the natural position followed by head in extended position. A two-belt chest-abdomen inductance plethysmograph was used to measure abdomen and ribcage movement. Inspiratory and expiratory tidal volumes (VT) were calculated retrospectively. Peak inspiratory airway pressure (PIP) was monitored by a pressure transducer in the rescuers mouth. Effectiveness of breathing was assessed by VT and the rate of effective breathing defined as VT greater than estimated anatomical dead space (2 ml/kg of ideal body weight).
Results: The rate of effective ventilation and PIP were similar during MMB and NMB (p>0.05). The inspiratory VT and expiratory VT during MMB with head in the neutral position (MMBn) were smaller than those of MNB with the head in neutral position (MNBn) and those of MNB with head in extended position (MNBe) respectively (p<0.05).
Conclusions: In head extended position, the effectiveness of breathing with MMB and MNB is equivalent. However, in the neutral position, MNB provides more effective breathing than MMB in apneic, non-paralyzed, adult subjects undergoing general anesthesia. Since lay persons may not optimize the airway during CPR, MNB breathing may provide more effective breathing than MMB.