HBOT a potential treatment for those with long COVID-19

Q: I got COVID-19, which wasn't too bad. But now I've got long COVID. I'm exhausted all the time, my heart races and I've got brain fog. It's derailing my life. I saw on the news that the method for treating scuba divers with the bends works for long COVID. Is this true? Can I get it?

A: As you may already know, long COVID-19 refers to the ongoing symptoms that can follow infection with SARS-CoV-2, the coronavirus that causes COVID-19. While the initial illness lasts from two to six weeks - depending on severity - the symptoms of long COVID persist for months - and even years.

The latest survey data shows long COVID affects at least 20% of people who have recovered from coronavirus infection. The chronic exhaustion you're experiencing is a common symptom, as are a range of cognitive issues. It has become clear that long COVID is sidelining millions of people, and researchers are seeking treatments to ease the symptoms.

Several studies have looked into the potential benefits of hyperbaric oxygen therapy, also referred to as HBOT. This is when someone breathes pure oxygen while in a pressurized chamber or room. You're correct that it's used to treat decompression sickness in divers, also referred to as the bends. Hyperbaric oxygen therapy is approved for a range of other uses, including carbon monoxide poisoning, wound healing, severe anemia, infectious diseases that starve the tissues of oxygen, and certain types of sudden and unexplained hearing loss.

The news stories that caught your attention are reporting the results of the most recent study into HBOT as a potential treatment for people living with long COVID. Conducted by researchers in Israel, the study looked at a group of patients whose cognitive symptoms of long COVID had lasted at least three months. Half underwent 40 sessions of HBOT over the course of two months. They received varying exposures of 100% oxygen over the course of 90 minutes, delivered via a mask, while in a hyperbaric chamber with twice the atmospheric pressure of sea level.

The other group of patients served as the control group. They also spent 40 sessions in the hyperbaric chamber, but breathed regular air, and at regular pressure. At the end of the study, the patients who underwent the genuine hyperbaric oxygen therapy reported a marked improvement in cognitive function. The therapy also had a positive effect on energy levels, sleep disruption and mood. The same results were not seen in the control group.

This echoes the results from research conducted last year by scientists in England. In that study, patients had 10 sessions of HBOT over the course of 12 days. Tests to assess fatigue and cognitive function also showed marked improvements between the start and the end of therapy. While the results are encouraging, the research is still in the early stages.

At this time, HBOT is not approved by the Food and Drug Administration for treatment of long COVID. It's also important to note it's not suitable for everyone. Someone with a cold, fever and certain lung, ear and eye conditions should not have HBOT.

Q: Can you please talk about why hot weather is so dangerous? We've had a couple of heat waves with high humidity, and my grandfather didn't even realize he had heat exhaustion. Air conditioning isn't common in our area, and our kids are struggling, too. Honestly, it's been a bit scary.

A: A series of extreme heat waves, often with high humidity, are making for a difficult summer in much of the United States. Even regions where the climate is typically mild are getting hit hard. The result has been a sharp increase in heat-related illnesses, hospitalizations and, tragically, deaths. This occurs because, in order to function properly, warm-blooded creatures need their core temperature to stay within a narrow range. For humans, it's somewhere in the neighborhood of 97 to 99 degrees Fahrenheit.

When ambient temperature, physical activity or a combination of the two cause us to overheat, our bodies use various physiological processes in an attempt to cool down. The first ones are flushing of the skin and sweating. The former sends blood to the surface of the skin in order to cool it, and the latter moistens the skin itself, allowing for an evaporative and cooling effect.

But when temperatures get high enough, flushing can't cool the blood. And on humid days, when water saturates the air, sweat evaporates far more slowly, if at all. With the body's natural cooling systems canceled out, core temperature begins to rise. This marks the advent of an increasingly serious range of heat-related illnesses.

The mildest of these illnesses, also known as hyperthermia, are heat-related dizziness or fainting and heat cramps. When these occur, the person should stop all activity, move to a cool, shaded place and gradually drink water to rehydrate.

A serious collection of heat-related symptoms is known as heat exhaustion. It is marked by dizziness, heavy sweating, clammy skin, headache, exhaustion, a weak and rapid pulse, decreased urine output, slightly elevated body temperature and sometimes nausea or vomiting.

In addition to taking the steps above, someone with heat exhaustion should directly cool their skin. This can be done with a cold bath or shower, or by spraying or sponging the skin with cool water.

If left untreated, heat exhaustion can quickly lead to heat stroke. Those symptoms include skin that is hot to the touch and often dry, body temperature of 104 Fahrenheit or higher, mental confusion, loss of consciousness and a rapid and pounding pulse. Heat stroke is an emergency. Immediate medical care is needed in order to prevent brain damage, organ damage and even death.

Never ignore any form of heat-related illness - even the mildest form can escalate into a medical emergency.

In this time of unusual summer heat, it's important to have a heat safety plan. Learn about the various options for staying cool that are available in your community. This includes public spaces that are air-conditioned such as malls, public libraries and senior citizen centers. Many communities open dedicated cooling centers during a heat wave. Stay abreast of weather reports. Whenever a heat wave strikes, stay safe by putting your safety plan into immediate action.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.