When I went through EMS education, I was taught that when ventilating a patient with a BVM that it was important to deliver as much of the content of the bag as possible. We would almost wring out the bag to get as much as possible. But were we really helping our patient?
Our Patient needed oxygen and if a little was good, a lot must be better. We ventilated hard, pushing the O2 in quickly. But without a secured advanced airway we ran into issue with abdominal distention.
When we bag, we must do so gently. If we push too hard we can push the epiglottis down and force all or part of the air into the stomach. Air in the stomach doesn’t help our patients and only creates a vomit fountain.
I was shown a great aid in teaching how to properly ventilate a patient. Using a BVM, attach an Endotrachial tube to the end immerse the end into a 3/4 full cup of water. If you bag fast the water will bubble out of the cup making a mess, but with practice you can ventilate without spilling the water. This is the proper way to ventilate a patient, gently.
Recent research has shown that Oxygen can destroy surfactant in the lungs. We need this to provide the “lubrication” to keep alveoli open. Think of washing sugar off of you counter-top, the water will always break up the sugar, but we we used a pressure sprayer it would break it up even faster. Fast bagging is the equivalent of a pressure sprayer while ventilating.
We’ve also found that we give far too much oxygen, we bag with 100% oxygen, under positive pressure, how long can we keep our patient’s lung compliance?
The last major faux pas of bagging is doing it too frequently. Our body breathes, in part, to maintain our acid/base balance. We rid ourselves of acid during the expiratory phase. If we bag too frequently, we prevent the body’s natural ability to rid acid. Ventilating once every 6-8 seconds for a non-perfusing patient and once every 5-6 for an a apnic yet perfusing patient would be sufficient.
Positive pressure ventilation can be very beneficial to our patient, but if we do it wrong can have many untoward effects. Slow down, be gentle and help our patients!
Medical Mondays 
Jay,
Not only is the oxygen itself corrosive to the surfactant, providing high concentrations of oxygen it replaces the nitrogen which is the majority of what we breathe in (78%). Since nitrogen is denser and not as easily absorbed through the alveoli, it is what provides our natural PEEP of 3-5 cm. of H2O. Once that nitrogen is replaced by oxygen, the oxygen is able to be absorbed leaving the alveoli empty and subject to collapse. This process is referred to as absorption atelecasis. This is why more and more we’re seeing a move from BVM ventilation to passive oxygenation during resuscitation.
Thanks,
Scott Masterson CCEMT-P/ FP-C
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Excellent Point Scott, Thank you.
I do suspect that we’ll be moving more toward venturied O2 percentages for resuscitation efforts in the future. Passive air is good, but they’re finding that the positive compression/decompression still only moves dead air spaces. Venturied positive pressure will allow us to get in needed oxygen but in lower percentages to help maintain homeostasis if revived.
Thanks for the input!
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“Recent research has shown that Oxygen can destroy surfactant in the lungs.”
I’m not familiar with this research. Is the effect significant for the time durations ski patrollers have their patients or is this more of a problem for patients on longer term oxygen therapy, for example, days, weeks, or hours. To put it in perspective, at my ski area, if I had a critical patient in my care for more than an hour, that isn’t impossible, but very low probability.
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Aaron,
I’m sorry it’s been so long to reply to you. There have been many studies dating back to the British Thoracic Society release in 2007.
Oxygen, in high concentrations can begin it’s effects on surfactant immediately, but in most healthy patients they can overcome this assault for a short period of time. It’s the poor of health that cannot recover from this assault.
There is also the trade off, if you have a significant trauma, getting oxygen into the system is far more important than the worry of surfactant reduction. Brain and central organ profusion takes precedence.
In the not too distant future, I do see us using a “venturi” system to allow us to introduce oxygen at higher than ambient concentrations, yet not use 100% as the standards.
I hope that you’re getting some snow this season. In the Midwest (I patrol in the UP of Michigan) we’re having a very hard time to get the weather for snowmaking and we’ve received next to nothing in the form of natural snow. Enjoy the season!
Jay
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