UPDATE 4/6/20: A pilot study on HBOT for COVID-19 is starting in New York.

Chen and colleagues have reported the results of 5 patients with severe to moderate Adult Respiratory Distress Syndrome (ARDS) treated with hyperbaric oxygen therapy (HBOT). Patients received a mean of 4.6 HBOT treatments in addition to usual care. Symptoms of hypoxia improved with the first treatment, and oxygen saturation significantly increased (P<0.01). Mean daily oxygen saturation improved to >95% over the treatment course. After HBOT, PaO2 and SaO2 were significantly increased (P<0.05) and Chest CT showed significant improvement in the appearance of the lungs. I’ve been getting calls and emails asking what I thought about this, so I asked Dr. Sandra Wainwright to guest blog her informal thoughts through the lens of a critical care/hyperbaric medicine physician.

Read more about the case reports here: https://www.ihausa.org/Hyperbaric_oxygen_therapy_in_the_treatment_ofCOVID-19_Severe_Cases.pdf


Late night thoughts on HBOT for Critically Ill patients with COVID-19 pneumonia

I am a Critical Care physician trained in Hyperbaric Medicine. Sadly, my ICU is currently full of critically ill patients with COVID-19 pneumonia, most of them intubated. My colleagues and I have been caring for them for several days, so I have some insight into the issue of critically ill patients with COVID-19 Pneumonia. In COVID-19 pneumonia, the lungs are not able to allow oxygen to diffuse to the bloodstream. I have read the article by Chen and colleagues. At least one hope is that the significant elevation in inspired oxygen during HBOT would enable oxygen to reach the arterioles even though the air sacs of the alveoli are damaged.

These are my thoughts off the top of my head. Please do not take anything I say as the opinion of anyone other than me, and my opinion might change. But, since you asked…

While treating these very sick patients, I had been mulling over the idea of using HBOT for COVID-19 pneumonia but disregarded it, at least for OUR Monoplace because we’re not set up to do critical care HBOT.  There are some hyperbaric facilities where Monoplace chambers are used to provide excellent critical care. However, if a facility is not experienced with HBOT in critically ill patients, I would not want to learn on a COVID-19 patient. Another obvious consideration is the infection control issue, including potential staff exposure. The chamber would require a terminal clean after each treatment. The virus apparently can live for quite a while on certain surfaces. Conceptually, HBOT for COVID-19 pneumonia patients makes more sense (to me) with a Mulitplace chamber, although there are fewer of those facilities. The whole issue of facility capability (staff and equipment) is complex. The key is always to know your limitations. I don’t think many facilities would be able to do this.

If you ask what I think insofar as the physiological rationale, I think HBOT is a viable option for COVID-19 hypoxia. I am unsure whether it is a PRACTICAL option. We are finding that a cytokine storm occurs around “day 7” of infection. About 6-10 days into the illness, this storm and its consequences can be quite severe. This cytokine storm can lead to severe Adult Respiratory Distress Syndrome (ARDS) and profound hypoxemia. Usually not many other organ systems are affected though we’re seeing some renal failure partly from hypotension. Hypotension affecting the kidneys may be due to the very high Positive End Expiratory Pressures (PEEP) required combined with underlying Chronic Kidney Disease, exacerbated by hypoxemia.  With regard to staff COVID-19 exposure, I feel a bit safer in the ICU with patients who are on ventilators (that have an n95 filter) than with patients who are coughing into the room. Naturally we clinicians wear n95 masks and protective gear. My point is that we have to consider the way in which the patient’s current breathing system might or might not pose a threat to the caregivers.

There are COVID-19 pneumonia patients who just “hang out” on Non Re-breather (NRB) face mask oxygen for several days. Some of them get better and some worsen and require intubation.  If we can avoid intubation, their length of stay in the ICU appears to be shortened somewhat. For complex reasons, lying prone (face down) improves arterial oxygen levels so we recommend patients “prone” themselves at night on NRB by simply lying on their stomach. Also early mobilization is helpful.  However, once a patient is intubated, they clearly cannot mobilize themselves. Once intubated, the best way to improve oxygenation is to keep them lying face down, or provide extracorporeal membrane oxygenation (ECMO).

Thus, HBOT may be an option for very sick but not yet intubated patients as way to keep intubation from becoming necessary. There may be a subset of patients who are on, for example 6 liters of nasal canula oxygen or on 100% NRB, and are still hypoxic. Those are the patients likely headed for intubation. If they were given HBOT via the Built in Breathing (BIBS) (which also has the advantage of protecting inside attendants from their respiratory particles), HBOT may be able to adequately oxygenate the blood and delay or prevent the need for intubation.

Right now all the intubated patients in ARDS from COVID-19 are being “bridged” with the ventilator. Meaning, we are trying to buy time, allowing them to survive the protracted hypoxemia and lung injury until some healing can occur. Intubated patients will be on the vent for about 2 weeks.  It is possible that HBOT could be a “bridge” to get patients past the need for intubation.  We also believe that HBOT will have an additive anti-inflammatory effect.

The paper reports only a small number of patients, so we have to be careful drawing conclusions. The risk of HBOT is generally low, although somewhat higher in sick patients. If it prevents intubation, it would be worth it. At least, that’s how I would feel if I were the patient, something which frankly, is possible.

There are a lot of considerations I am  not properly addressing such at the issue of respiratory arrest while the patient is in the chamber and the challenge of responding to that. I have been asked about taking already intubated patients from the ICU to undergo HBOT. I have to say that keeping them oxygenated has required all of the skill we have and all of the capabilities of our ICU ventilators. Patients have to be removed from that environment to get to HBOT, and their respiratory support during the transport is not as good as it is in the unit, to say nothing of the ventilator capability in the chamber. We want to “first do no harm.” Thus, I would not recommend moving a critically ill patient with COVID-19 pneumonia so that they can undergo HBOT when the transport itself is risky. It makes far better sense to me to use HBOT (if possible) to try to prevent intubation, but this would have to be done very thoughtfully and the mere availability of a chamber is not sufficient. The entire HBOT team would have to be skilled at handling very sick patients and it would require careful coordination. For these reasons and others, I do not see adjunctive HBOT as a commonly available option. However, if there is one good that is coming out of this crisis, it is the speed with which innovation is occurring when everyone works together. If we can overcome barriers so that patients are not exposed to the risk of HARM in order to give HBOT a try, then in places where it can be performed safely, it may be a treatment option – with a LOT of caveats.

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