Questions; 1. Above what level do you think about need for hyperbaric O2 chamber? 2. Our hospital is 2 hrs away over a dangerous pass,from a chamber. If patient comes in with a level of say 25, but has normal level of consciousness at the time with minimal symptoms, when is it worth transferring for hyperbaric O2 therapy? 3. How long should O2 therapy continue if just by a mask with rebreathing reservoir?
Questions 1&2: COHb levels should be used as a screening tool to confirm that there was exposure. The decision for hyperbaric therapy (HBO) is made based on the risk of delayed neuropsychiatric sequelae (DNS). Increase DNS risks include: age >36, prolonged exposure, loss of consciousness, and COhb >25%. Other factors I consider during a consult include ambient CO level at scene (ppm), altered MS, abnormal cerebellar exam, persistent symptoms despite surface O2, pregnancy status, lactate and troponin levels, ECG abnormality. HBO is most useful if started in 6 hours.
Question 3: Remember that normal baric oxygen does not decrease risk of DNS. The half life of COhb on NRB O2 mask is roughly 1 hour. So six hours should be plenty to eliminate the COhb. But please remember that is not our main goal with HBO...
Dear William, The publication you have referenced is one the HBO community knows well. The study was performed in the 90s before the NEJM landmark publication considered definitive (Weaver LK, et al. Hyperbaric oxygen for acute carbon monoxide poisoning. N Engl J Med (2002) 347:1057-1067). The protocol used in this study is not the universally accepted depth and length of treatment we have used since the NEJM study publication. Not sure why it took the authors 11 years to publish their study...
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Lizi T., Dr - July 3, 2016 5:25 PM
Questions;
1. Above what level do you think about need for hyperbaric O2 chamber?
2. Our hospital is 2 hrs away over a dangerous pass,from a chamber. If patient comes in with a level of say 25, but has normal level of consciousness at the time with minimal symptoms, when is it worth transferring for hyperbaric O2 therapy?
3. How long should O2 therapy continue if just by a mask with rebreathing reservoir?
Siamak M, MD - July 4, 2016 4:04 AM
Dear Lizi, thanks for the questions.
Questions 1&2: COHb levels should be used as a screening tool to confirm that there was exposure. The decision for hyperbaric therapy (HBO) is made based on the risk of delayed neuropsychiatric sequelae (DNS). Increase DNS risks include: age >36, prolonged exposure, loss of consciousness, and COhb >25%. Other factors I consider during a consult include ambient CO level at scene (ppm), altered MS, abnormal cerebellar exam, persistent symptoms despite surface O2, pregnancy status, lactate and troponin levels, ECG abnormality. HBO is most useful if started in 6 hours.
Question 3: Remember that normal baric oxygen does not decrease risk of DNS. The half life of COhb on NRB O2 mask is roughly 1 hour. So six hours should be plenty to eliminate the COhb. But please remember that is not our main goal with HBO...
William A. M. - November 17, 2016 11:08 AM
Intensive Care Med. 2011 Mar;37(3):486-92. doi: 10.1007/s00134-010-2093-0. Epub 2010 Dec 2.
Hyperbaric oxygen therapy for acute domestic carbon monoxide poisoning: two randomized controlled trials.
Annane D1, Chadda K, Gajdos P, Jars-Guincestre MC, Chevret S, Raphael JC.
Thank you for your valuable information.
I wonder if you could comment on the paper cited above.
---WAM, MD
Siamak M, MD - November 21, 2016 8:38 AM
Dear William,
The publication you have referenced is one the HBO community knows well. The study was performed in the 90s before the NEJM landmark publication considered definitive (Weaver LK, et al. Hyperbaric oxygen for acute carbon monoxide poisoning. N Engl J Med (2002) 347:1057-1067). The protocol used in this study is not the universally accepted depth and length of treatment we have used since the NEJM study publication. Not sure why it took the authors 11 years to publish their study...