Dyshemoglobinemia: Methemoglobin and Carbon Monoxide Poisoning (ABG Interpretation - Lesson 19)
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- Опубликовано: 23 июл 2024
- A discussion of the pathophysiology and etiology of methemoglobinemia and carbon monoxide poisoning, including a review of the structure and function of hemoglobin, and the basic principles behind pulse oximetry and co-oximetry.
Very helpful in helping me understand my Late Mother's Iatrogenic Malfeasance manipulated Personal Injuries and foreseeable violent Death-Murder etc.
Thank you Dr Strong! It is good lecture ,even went on review physiology of it. I can’t thank you enough.
Beautiful video. I really learned a lot more on CO related complications.
Thank you for this contribution to the educational world 👍🏻
Great teacher you are!! Helped a whole lot for my studies.
Commenting on this late, but you you have cleared up so many concepts for me that I have been trying unsuccessfully to understand since the beginning of medical school. Thank you! I have the utmost admiration for you and all the others who try to make fantastic medical education accessible to those all over the world.
I had a recent extremely interesting case of a patient with suspicion of lymphoma started on rasburicase and subsequent desaturation on pulse oximetry he remind completely asymptomatic in fact nurses mentioned that increasing oxygen reduced his O2 sat. Abgs showed po2 at 9kps methb of 9 he subsequently dropped his hb from 90 to 68 which triggered ix revealing g6pd def is the methb in this case due to the free O2 radicals
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@@zareenawais6318 Rasburicase promotes the oxidation of uric acid to a soluble , easily excreted product called (allantoin) through the enzyme URATE OXIDASE !
Hydrogen peroxide (H2O2) is a byproduct of the reaction , which when released from the lymphoma cells into the circulation is taken up by RBCs to be reduced to water !
GLUTATHIONE PEROXIDASE enzyme in the RBCs is responsible for reducing hydrogen peroxide to water using its coenzyme reduced glutathione ; which in turn gets reduced by NADPH + H through a reaction catalyzed by GLUTATHIONE REDUCTASE enzyme !
In case of G6PD enzyme deficiency ; the impaired production of NADPH + H results in the accumulation of H2O2 in the RBCs & eventual hemolysis .
OR oxidation of hemoglobin to methemoglobin by oxygen free radicals (OFRs) during oxygen transport , a process normally suppressed by the (NADPH methemoglobin reductase) enzyme that reduces methemoglobin to hemoglobin !
But in case of G6PD deficiency , the low levels of the reducing agent NADPH + H result in failed methemoglobin reduction !
Increasing oxygen to elevate SpO2 resulted in accumulation of oxygen free radicals (OFRs) in the RBCs & impaired reduction of (OFRs) by (Glutathione peroxidase enzyme) secondary to low levels of NADPH + H !
SpO2 dropped suddenly from 90 to 68 possibly due to hemolysis & methemoglobinemia !
Lord knows best !
Great lecture, this helped me a LOT! Glad I found your channel.
Great!! Dr Eric God bless you for sharing freely. You're really great teacher. Keep it up.
Thank you Dr.Eric this presentation helps me a lot for my finals...
love all these videos, thank you
thanks you! Dr.Eric! It solved a big confusion of me that why the new edition of Harrison have removed the algorithm which based on A-a gradient change. the last part of the explanation that there are no exact algorithm to make direct diagnosis with A-a gradient change because the mixed entities of the disease, explained why the new edition of the Harrison removed the table "Approach to patient with hypoxemia".
Dr. Khan, I hope you enjoyed the video and thanks for the comment. You are right that I used the normal Aa gradient formula for patients on supplemental o2. The additional supp. O2 term, (50 x (FiO2 - 0.21)), ends up being 0, so it doesn't impact the final answer.
Thank you Dr. Strong
This was incredibly helpful! Thankyou
Congratulations, and best of luck!
Great research, thank you so much for share this, I needed to know how long can a person be exposed to carbon monoxide depending on concentration in the environment, this is really helpful for my design project, best regards from Bogotá, Colombia.
How about upper zones of the lungs is normal but the left and right diagrams was absent. What should we think
Fantastic👍🏻👍🏻
Gustavo, I'm very sorry, just seeing your question now. I'm afraid a quick literature search failed to find any information more specific than that presented in the video (around the 23rd min). You may need to consult a textbook on toxicology or emergency medicine.
Thanks Doctor
Useful..thanks
@Strong Medicine
How to check Methelmoglobin percentage in blood. How many test should be done ? I contacted with nitrate from that day problem started.
hello Dr. Eric, i love your channel and hope you keep it up. my question is @ 30:11. at step 1, how was the patients 60% FiO2 derived from a 10L facemask? if i use the formula fio2 = .21 + (.03 x O2 in lpm), i get a value of PAO2 318.63, instead of 383. thanks!
Carl, thanks for the feedback and great question. The equation you've listed is my adaptation of an empirically derived equation for FiO2 in patients on nasal cannula, in order to account (in an extremely approximate way) for tachypnea. However, it only applies for patients on nasal cannula. When breathing via face mask, tachypnic patients probably take in relatively less ambient air compared to what they would on nasal cannula. Empiric evidence (I'm unable to quickly find the exact data aside from a reference in an ICU textbook) has apparently found that oxygen delivery via simple facemask maxes out at 60% FIO2 around 10L. But keep in mind that all estimates of FIO2 are extremely approximate, unless the patient is on room air, a Venturi mask, or mechanical ventilator; even then, only room air is probably 100% accurate.
Eric's Medical Lectures
thanks for the clarification! all the best
Why in example 1, pt has normal gradient HYPOXEMIA since she has PaO2 of 340??
Sorry for the misunderstanding but
C.O and Meth HB
- Won't allow O2 to off load at the tissues
- If C.O or meth molecule is already attached to HB then this will prevent O2 from binding onto the HB
Clues to the presence of methemoglobinaemia -Cyanosis despite normal SaO2.Sir i am little confused.......
Genius !
thanks but y u used suplemental oxygent Aa gradient age corected formula i think pts is on room air
Dr. Eric, thank you, that is enough to justify and support the concept of my project, now I am nominated to the World Design Impact Prize 2013, I cannot paste the link, but If you want to see please search on google World Design Impact, project CO-RAZÓN. Regards, G.
perhaps the carbon monoxide lady in the tank was pregnant