Most of the studies on HBOT have been case studies that describe what happens to patients in clinical practice. The “gold standard” for evidenced based medicine (EBM) is the placebo-controlled, double-blind cross over study. A placebo is a kind of dummy treatment; in the case of HBOT, this would be a sham session in a chamber where air was used instead of O2. This gives researchers something to compare to the “real” treatment. Double-blind means that neither the patients nor the researchers know who is in which group. This is to mitigate the chances of the power of expectation and suggestion. Cross-over means that each group goes through two phases, generally with a “wash out” period in between. Wash out is just a given length of time to cancel out any effects of the “real” treatment.
One of the problems with this type of study is that the effects of HBOT are generally long lasting. The cross-over is when the group that had the “real” treatment then goes through the placebo phase and vice versa. The other real difficulty with this type of study is of an ethical nature. If someone is very sick and there is a possibility that HBOT could help is it morally justifiable to put someone through the placebo stage, thereby wasting valuable time that could have been used to mitigate suffering and facilitate healing?
There is also evidence that HBOT can be extremely time sensitive. For example, the sooner a stroke patient begins treatment with HBOT, the better the outcome. A further complication is the immense expense and paperwork of doing these controlled studies. In the U.S., for example, three stages of study must be reviewed by the FDA.
A longitudinal case study follows a patient through several stages of treatment. Most patients of HBOT use it as a “last resort,” after they have tried virtually all of the conventional treatments for their particular condition. These studies are particularly interesting in that they can show significant clinical improvements when all else has failed.
Evidence-based medicine (EBM) seeks to use the best available evidence gained from the scientific method for clinical decision making. Evidence quality can range from meta-analyses and systematic reviews of double-blind, placebo-controlled studies at the high end, to conventional wisdom at the bottom end. Another aspect of EBM is that it does take into consideration quality and value of life issues. Ethical considerations do play a part in EBM—for instance, in open-heart surgery, it is generally seen to be unethical to run placebo trials. Criticism of EBM exists primarily depending on how it is used. There is concern that it can be wrongly used (as can any statistics) for rationing health care and resources.
The clinical aspects of diving hyperbarics were basically developed by the military, while clinical HBOT has been developed by civilians who have pioneered the use of HBOT for the treatment of a spectrum of brain pathologies including stroke, traumatic brain injury, post traumatic stress disorder, cerebral palsy, multiple sclerosis, autism, and other neurological conditions. HBOT is the primary treatment for DCI, gas gangrene and carbon monoxide poisoning.
Many studies indicate that healing of persistent and severe wounds is accelerated by at least 30% with HBOT. It has been shown to help in the formation of new blood vessels. It is routinely used in healing patients after elective cosmetic and plastic surgery for those patients able to afford it.
Many clinicians and researchers are of the opinion that the medical consumer must drive the acceptance and use of HBOT. There are over 30,000 scientific studies on HBOT published in medical, diving, and clinical journals as of 1998. In the Cochrane Reviews, a meta database that merges medical databases like medline and pubmed, for just about every indication that HBOT is used it concludes only that more studies are needed. In the meantime, HBOT is being used for a vast array of “off-label” conditions, including as adjunctive therapy for certain conditions such as stroke, neurological conditions and Lyme disease, with some success. Much of the art and science of HBOT involves timing—how soon the patient begins therapy, what pressure is used, the length and frequency of the sessions, and how many total sessions are needed. This varies greatly from condition to condition and from patient to patient.
In addition to the expense of installing a chamber, for HBOT to be covered under Medicare in the U.S., a hyperbaric-trained physician must be in constant attendance during the entire treatment. The MD’s presence may not be delegated because treatments (or dives) require careful monitoring for potential complications.
HBOT is usually offered as a referral and consultation service, unless used in emergency medicine. A consultation appointment is made for the patient once appropriate case documentation is received. Copies of treatment documents are mailed to referring physicians.
Treatment protocols are established by the attending physician. Besides beneficial effects, HBOT can produce toxic effects if administered or monitored inappropriately. Safe time, dose, and depth limits have been established and these form the basis for treatment protocols. With the exception of carbon monoxide and/or cyanide poisoning, decompression sickness and cerebral arterial gas embolism, treatments may last about two hours and may be given once, twice, or sometimes three times per day.
Treatment for most acute cases is about ten days; chronic cases may require treatment for 30 days or more. Treatments can be administered on an inpatient or outpatient basis. Patients with wound healing problems usually require about 40 treatments, usually Monday through Friday. Patients with acute problems such as decompression illness or carbon monoxide poisoning usually need only 1-2 treatments, given as part of emergency medicine.