Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.See all posts »
Mouth-to-Mouth Breathing Versus Mask-Assisted Breathing
When a person performs cardiopulmonary (heart and lung) resuscitation (CPR), it is sometimes recommended to provide rescue breathing. This is certainly the case when the primary cause of the victim’s difficulty relates to failure to breathe adequately, such as with a drowning episode. When CPR first arrived on the landscape, laypersons were trained to perform mouth-to-mouth breathing (for adults) or mouth-to-mouth and nose breathing (for infants and small children).
Following growing concern about transmission of diseases from blood and body fluids, laypersons were introduced to using masks or something similar to allow them to provide breathing assistance (“artificial respiration,” “artificial ventilation,” “rescue breathing,” etc.) to non-breathing persons. Masks have been used for decades by professional rescuers for ventilating patients, often in conjunction with the use of bags in a “bag-valve-mask” configuration. The valve between the mask and bag provides for one-way flow and prevents the backwash of vomitus, blood, liquid from the lungs, or other fluids that might diminish the effectiveness of the technique.
A number of excellent masks and face shields are available on the market for rescuers to be able to (relatively) safely blow air into a victim’s lungs. One example is the NuMask, which is very useful and definitely indicated for personal (rescuer) protection. However, the NuMask requires some practice to use successfully. The masks typically used by professional rescuers require training and a strong set of hands (sometimes two sets of hands, depending on the situation and facial anatomy of the victim) to obtain a proper mask seal that can be maintained during rescue breathing using a bag.
Current advice to laypeople who might be called upon to provide rescue breathing is to carry and utilize a shield or shielding mask. I recently read a report from Reuters in which it was commented that a “small study suggests that lifeguards may perform better with direct mouth-to-mouth breathing.” For the study reported by this news agency, trained lifeguards performed CPR on mannequins using each of three breathing techniques – mouth-to-mouth, pocket mask, and bag-valve-mask. In this study, using visible chest rise in the mannequin, the lifeguards were successful 91 percent of the time with mouth-to-mouth, 79 percent of the time with pocket masks and 59 percent of the time with bag-valve-mask setups.
This announcement makes perfect sense to me, because I have performed all three techniques. With mouth-to-mouth breathing, the seal is created in a dynamic fashion by using the rescuer’s pliable lips to create a firm (as airtight as possible) closure over the victim’s mouth. This may be aesthetically displeasing, but it is effective and efficient. One knows exactly how firmly to press, and can change the lip (seal) position instantly to achieve the best seal possible. At the other end of the spectrum is the bag-valve-mask apparatus, which requires fairly precise placement, and is influenced by the victim’s facial anatomy, hair, and slippery factors like oral secretions, sweat, exogenous water, blood, and vomited gastric contents. Furthermore, it requires a reasonable amount of grip strength, sufficiently large hands, and good technique to achieve and maintain the seal. Somewhere in the middle is the smaller “pocket” rescue mask or shield, which usually fits fairly easily onto the victim and is easy to hold in place while the rescuer blows into it.
It is important to observe, as did Reuters, that this study could not be used to infer any direct effect on survivor outcome, either morbidity or mortality, because it was performed on mannequins, not on real victims. Other factors should be considered besides chest rise, such as the fact that supplemental oxygen can be administered using a port into the bag-valve-mask apparatus, as well as knowing how long it takes for a rescuer to become fatigued, thereby rendering any technique less effective or ineffective.
Given the risks associated with disease transmission (which is estimated, but not definitively measured, in the literature), we cannot infer that the improvement in effect with mouth-to-mouth over the other techniques would argue for a change in recommendations. They would, however, certainly emphasize the importance of proper training and maintenance of skills. Learning a technique one time does not solve anyone’s educational needs over the long term. Refreshers are essential to sharpen your skills to function well in an emergency situation.
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