Have you ever been working a cardiac arrest and noticed your partner or another responder is squeezing the BVM (Bag Valve Mask) a little to hard and fast? You can tell their adrenaline is pumping. All they’re thinking about while squeezing the BVM is: “they need more oxygen, they need more oxygen, the faster I squeeze the bag the more oxygen they will get, that’s what they need!” You notice they are squeezing the bag around 25-30 bpm (breaths per min) when they should be squeezing the bag around 10 bpm or 1 breath every 6 seconds (according to ACLS guidelines). You eventually have to grab their hand and remind them to slow down on the bagging.
Well today, we are going to briefly explain the importance of reminding ourselves and partners the need to avoid hyperventilating our cardiac arrest patients. Excessive ventilation can result in an increase in intrathoracic pressure, a decrease in coronary perfusion pressures, and lastly a decrease in survival rates! The increase in intrathoracic pressure reduces coronary perfusion by reducing blood flow back to the heart. That’s the last thing you’d want to happen while managing your cardiac arrest patients. Hyperventilating can impact your effectiveness in CPR. The recoil phrase during CPR (decompression phrase) is what is allowing the patient’s heart to refill with blood. Think of the compression phase being the systolic in the cardiac cycle (the squeezing of the heart) and decompression phase being the diastolic in the cardiac cycle (the relaxation of the heart). Increased intrathoracic pressure limits cardiac filling. The best CPR ever is still going to be ineffective in the setting of increased intrathoracic pressures secondary to lung hyperinflation. Animal studies have shown a decrease in survival rates with hyperventilation. So does any of this matter if the BVM is not attached to an ET tube or king? Let’s say the patient is being BVM’d with only the mask and an OPA (Oropharyngeal Airway) in place? Of course it does! This causes the patient to have an increase in gastric inflation (stomach filling with air), increasing the likelihood of vomiting and possible aspiration.
Scopeducation team: Regardless of your skill level, we have seen firefighters, skilled paramedics, EMT-B, and even respiratory therapists fall victim to hyperinflation. We understand, cardiac arrests are high acuity/high stress patients. Our adrenaline is running at full blast and we tend to be overzealous in our ventilations. Even when we get ROSC on these patients, you need to still still administer the perfect amount of O2 to these patients due to the circulatory collapse effect of hyperventilation. If you are using a large adult BVM, try using three fingers to squeeze the bag on the back 1/3 of the bag to ensure you don’t over do it. Better yet, use a pediatric BVM! You just need to see a small amount of chest rise. If you are in charge of ventilations, you should learn to block out all other stimulus and just focus on ventilating your patients. Sounds like a no brainer but it’s easy to fall into the hyperventilation/hyperinflation trap. How do we get better with this? Practice on manikins because you can’t hurt them. The more practice, the better you will get. And finally admit that we can always improve no matter what your experience level is. It would be nice for the team leader to watch and make sure the person ventilating is doing it adequately as well to add a little safe guard.
This site is meant to be used for educational use only. We strive to push evidence based medicine with no bias to help you obtain all the important information. You should always follow your protocols that have been set in place.
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-Jesse Duncan NRP
Chin, A., Taher, A., Thomas, A., Bigham, B., Thoma, B., & Woods, R. (2018, November 26). CPR Update Series Part 5 – Avoiding excessive ventilation. Retrieved September 21, 2020, from https://canadiem.org/cpr-update-series-part-5-avoiding-excessive-ventilation/
CPR Hyperventilation May Endanger Arrest Victims. (2004, June 30). Retrieved September 21, 2020, from https://www.emsworld.com/article/10324596/cpr-hyperventilation-may-endanger-arrest-victims
Lundström, N., Henriksson, G., Börjesson, O., Jonsson Fagerlund, M., & Petersson, J. (2019, January 29). Circulatory Collapse due to Hyperinflation in a Patient with Tracheobronchomalacia: A Case Report and Brief Review. Retrieved September 21, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6374882/
Review of Respiratory Arrest. (n.d.). Retrieved September 21, 2020, from https://acls-algorithms.com/respiratory-arrest/