Emergency Indication
Hyperbaric Oxygen Therapy for Carbon Monoxide Poisoning
Carbon monoxide poisoning is a medical emergency: get into fresh air and call 911. Hospital hyperbaric teams may give one to three HBOT sessions to higher-risk patients, usually within the first day. Generations Wellness is an outpatient center and does not provide emergency hyperbaric treatment.
This is a medical emergency. Call 911 or go to the nearest emergency room. If you or someone near you may have carbon monoxide poisoning, leave the building and get into fresh air first. For poisoning questions, California Poison Control is available 24/7 at 1-800-222-1222. Emergency hyperbaric treatment is delivered at hospital-based chambers. Generations Wellness is an outpatient center in Modesto and does not provide emergency HBOT.
The Basics
What Carbon Monoxide Poisoning Does to the Body
Carbon monoxide (CO) is a gas you cannot see, smell or taste. It comes from burning fuel: gas furnaces and water heaters, generators, cars, charcoal grills, wood stoves and propane heaters. When fuel burns in a space without enough fresh air, CO builds up.
Once you breathe it in, CO grabs onto hemoglobin, the protein in red blood cells that carries oxygen. It binds roughly 200 to 250 times more tightly than oxygen does. The result is called carboxyhemoglobin (COHb), and blood loaded with it delivers much less oxygen to the brain and heart.
That is only part of the harm. CO also injures cells directly and sets off inflammation, especially in the brain. This is why a blood COHb level does not always match how sick someone is, and why some people seem to recover and then develop problems weeks later.
Warning signs
- Headache, dizziness, weakness or tiredness
- Nausea or vomiting
- Confusion, trouble thinking, or blurred vision
- Chest pain or a racing heartbeat
- Fainting, seizures or loss of consciousness
Early symptoms are often mistaken for the flu. Clues that point to CO instead: several people or pets in the same home feel sick at once, symptoms ease when you leave the house, or a fuel-burning appliance, generator or car was running nearby. People who are asleep or drunk can die from CO before they notice any symptoms.
The Mechanism
Why Hyperbaric Oxygen Is Used for CO Poisoning
Every patient with suspected CO poisoning gets high-flow oxygen by mask right away. For higher-risk patients, hospital teams may add hyperbaric oxygen therapy. There are two reasons.
It clears CO faster. Breathing oxygen under pressure pushes carbon monoxide off hemoglobin much more quickly. The time it takes for the CO level to fall by half changes a great deal depending on what you breathe:
| What the patient breathes | Approximate CO half-life |
|---|---|
| Room air | About 4 to 5 hours |
| 100% oxygen by mask, normal pressure | About 60 to 90 minutes |
| 100% oxygen in a hyperbaric chamber (about 2.5 to 3.0 ATA) | About 20 to 30 minutes |
It may protect the brain. Research suggests hyperbaric oxygen, and not ordinary mask oxygen, may interrupt the inflammatory chain reaction linked to delayed brain injury after CO exposure. This is the main outcome clinical trials have tried to measure. For a plain explanation of how pressurized oxygen dissolves into the blood, see how pressurized oxygen dissolves into plasma.
Carbon monoxide poisoning is one of the FDA-cleared indications for hyperbaric chambers, and it is one of the oldest indications on the Undersea and Hyperbaric Medical Society (UHMS) list. You can see the full list of cleared conditions on our conditions page.
Hospital Criteria
Who Is Treated With HBOT After CO Exposure
Not everyone with CO poisoning needs a hyperbaric chamber. Hospital hyperbaric physicians commonly consider HBOT when a patient has one or more of these:
- Any loss of consciousness, even briefly
- Neurological signs, such as confusion, seizures or an abnormal exam
- Signs of heart strain, such as chest pain, an abnormal heart rhythm or ischemia on testing
- A COHb level of 25% or higher (many centers use this threshold even without symptoms)
- Pregnancy with a COHb level around 15% to 20% or higher, or signs of fetal distress
- Symptoms that continue after a period of mask oxygen
Criteria vary from center to center, and the decision always rests with the treating physicians. Hyperbaric oxygen at these pressures has its own risks, including ear and sinus pressure injury and, rarely, oxygen toxicity seizures, which hospital teams monitor for. Read more in our overview of HBOT safety.
Timing
How Many Hyperbaric Treatments for Carbon Monoxide Poisoning, and How Soon
HBOT for CO poisoning is not a long course. Most protocols use one to three sessions, usually within the first 24 hours. The best-known protocol comes from the 2002 Weaver trial, which gave three sessions within 24 hours:
| Session | Pressure | Timing |
|---|---|---|
| Session 1 | 3.0 ATA at first, then 2.0 ATA | As soon as possible, within 24 hours of exposure |
| Session 2 | 2.0 ATA | Within the first 24 hours |
| Session 3 | 2.0 ATA | Within the first 24 hours |
Hyperbaric physicians generally aim to start as early as they safely can, and many centers consider the first six hours the most valuable window. Treatment that starts later is sometimes still given to patients whose symptoms persist. Stabilizing breathing, heart rhythm and blood pressure always comes first.
Honest Evidence
What the Evidence Shows
The research on HBOT for CO poisoning is genuinely mixed, and it helps to see both the strongest single trial and the pooled review side by side.
| Study | Design | Finding | Limitation |
|---|---|---|---|
| Weaver et al., NEJM 2002 | Double-blind randomized trial, 152 patients; three HBOT sessions vs. normal-pressure oxygen | Cognitive problems at 6 weeks in 25% of the HBOT group vs. 46% of the comparison group (p=0.007); the difference was still present at 12 months | Stopped early after an interim analysis showed benefit, which can overstate the size of an effect; one research group |
| Buckley et al., Cochrane review 2011 | Systematic review; six randomized trials, 1,361 participants | Pooled odds ratio for neurological problems 0.78 (95% CI 0.54 to 1.12), not statistically significant | Trials differed widely in pressures, timing, patients and outcome measures; authors called for a new multicenter trial |
Put simply: the best-designed single trial favored HBOT, but when all the trials are pooled, the results are inconsistent and do not prove a benefit. Even so, UHMS continues to list CO poisoning as an indication, and many hospital hyperbaric programs still recommend HBOT for patients who meet the criteria above. No study can predict how any one person will do.
After Discharge
Delayed Neurological Sequelae: Problems That Appear Later
Some people appear to recover fully from CO poisoning, then develop new problems days to weeks later. Doctors call this delayed neurological sequelae (DNS). Published studies report it in roughly 10% to 30% of poisoned patients, depending on how it is defined and measured.
DNS can look like:
- Memory loss or trouble concentrating
- Personality changes, depression or anxiety
- Movement problems, such as stiffness, slowness or trouble walking
- Loss of bladder control in more severe cases
Preventing DNS is the main reason hospitals use HBOT for higher-risk patients. Whatever treatment someone received, follow-up after discharge matters. Keep your follow-up appointments with your primary care doctor, and report any new memory, mood or movement changes promptly. Your doctors may arrange neurological or neuropsychological testing if symptoms appear.
Near Modesto
Where Emergency HBOT Happens Near Modesto
You do not need to find a hyperbaric chamber yourself, and you should not try to drive to one. Emergency hyperbaric treatment is arranged by emergency physicians, not by patients.
- Call 911 or go to the nearest emergency department. Hospital emergency departments in the area, including Doctors Medical Center, Memorial Medical Center and Kaiser Permanente in Modesto and Emanuel Medical Center in Turlock, can give oxygen, check your COHb level and stabilize you.
- Emergency physicians coordinate transfer. If HBOT is indicated, the emergency team contacts a hospital-based hyperbaric facility that is staffed and able to accept the patient, and arranges the transfer.
- Poison Control can help. California Poison Control (1-800-222-1222) is free, confidential and available around the clock, for the public and for health professionals.
Generations Wellness
Our Outpatient Role, Honestly
Generations Wellness is a physician-directed outpatient center under Dr. Rajwinder Singh Bahia, MD. We do not provide emergency hyperbaric treatment, and carbon monoxide poisoning is not something to bring to our center. If you think you have been exposed, call 911.
Follow-up care after CO poisoning is led by the hospital team and your own doctors. That may include checkups with your primary care doctor, neurological evaluation if new symptoms appear, and a home safety check before you return.
Once you are stable and home, our team is glad to talk with you. We can answer general questions about hyperbaric oxygen therapy, explain our physician-directed process, and tell you honestly whether anything we offer is relevant to you. Physicians with questions can find information for referring physicians. For the other hospital-only uses of HBOT, see other emergency indications treated at hospital chambers.
Central Valley Homes
Preventing CO Poisoning in the Central Valley
In the Central Valley, CO risk rises in the colder months, when furnaces and heaters run and winter storms can knock out power. Generators and improvised heating cause many poisonings. A few habits prevent most of them:
- Keep generators outside, more than 20 feet from any window, door or vent. Never run one in a garage, carport or basement.
- Never run a car in a garage, even with the garage door open.
- Use charcoal grills and camp stoves outdoors only. Never use a gas oven or stove to heat your home.
- Install CO alarms on every level of your home and near sleeping areas, test them, and replace batteries on schedule.
- Have fuel-burning appliances checked by a qualified technician every year, before heating season.
California law (Health and Safety Code section 17926) requires carbon monoxide devices in dwelling units that have a fossil-fuel-burning heater or appliance, a fireplace, or an attached garage. A smoke alarm alone does not detect carbon monoxide unless it is a combination smoke and CO alarm, so check the label.
If a CO alarm sounds, get everyone, including pets, outside into fresh air right away, then call 911 from outside. Do not go back in until emergency responders say it is safe.
Important
Generations Wellness does not provide emergency hyperbaric treatment. For suspected carbon monoxide poisoning, call 911. A physician assessment is required before beginning any HBOT at our center, and HBOT complements, and never replaces, the treatment prescribed by your doctors.
Questions
Carbon Monoxide Poisoning and HBOT: Frequently Asked Questions
How many hyperbaric treatments are needed for carbon monoxide poisoning?
Usually one to three sessions within the first 24 hours, decided by the hospital hyperbaric physician. It is not a multi-week course.
Can I get hyperbaric oxygen for carbon monoxide poisoning in Modesto?
Emergency HBOT is arranged through the emergency department, not an outpatient center, so call 911. Emergency physicians stabilize you and coordinate transfer to a hospital-based hyperbaric facility when HBOT is indicated.
What carboxyhemoglobin level needs a hyperbaric chamber?
Many centers consider HBOT at a COHb of 25% or higher, and at lower levels when there was loss of consciousness, neurological signs, heart effects or pregnancy. The decision belongs to the treating physician.
Is normal oxygen by mask enough?
High-flow mask oxygen is the first treatment for everyone and is enough for many people. Hospitals may add HBOT for higher-risk patients because it clears CO faster and may reduce delayed brain effects, though pooled trial results are mixed.
What are delayed neurological sequelae?
They are memory, concentration, mood or movement problems that appear days to weeks after CO poisoning. Report any new symptoms like these to your doctor promptly.
Sources
- Undersea and Hyperbaric Medical Society. Hyperbaric Oxygen Therapy Indications. uhms.org
- Weaver LK, et al. Hyperbaric Oxygen for Acute Carbon Monoxide Poisoning. N Engl J Med. 2002;347:1057–67. nejm.org
- Buckley NA, et al. Hyperbaric oxygen for carbon monoxide poisoning. Cochrane Database Syst Rev. 2011;CD002041. cochranelibrary.com
- Weaver LK. Carbon Monoxide Poisoning. N Engl J Med. 2009;360:1217–25. nejm.org
- Centers for Disease Control and Prevention. Carbon Monoxide Poisoning. cdc.gov
- California Poison Control System. calpoison.org
- U.S. Food and Drug Administration. Hyperbaric Oxygen Therapy: Get the Facts. fda.gov
- California Health and Safety Code section 17926 (carbon monoxide devices). leginfo.legislature.ca.gov
This page is educational and not medical advice. If you suspect carbon monoxide poisoning, call 911. Generations Wellness does not provide emergency hyperbaric treatment. See our full medical disclaimer, including emergency numbers.
If This Is an Emergency
Call 911 First
Emergency hyperbaric treatment happens in hospital settings. For follow-up questions once you are stable, our team is glad to talk.
Prefer to talk? (369) 222-0979