Interest in low temperature treatment is increasing and whole body cryotherapy (WBC) devices are becoming available not only in medical centers but also in local gyms and spa centers.
Many governments and medical professionals have thus turned attention to WBC, evaluating the treatment for its effectiveness and safety. The US Food and Drug Administration (FDA), for example, issued a statement in July 2016 alerting consumers to both the unproven benefits and risks posed by WBC.
I agree with the FDA on many points. Safety of the user is undisputedly a primary issue, and as such users must be fully informed about various WBC devices and associated risks of each. I disagree, however, with the FDA’s blanket warning against WBC, which includes both procedures conducted inside enclosed chambers that don’t expose users to cryogens and cryosaunas where users stand in vapor with only their heads above the tank.
The FDA, for example, notes “potential hazards include asphyxiation, especially when liquid nitrogen (LN2) is used for cooling,” but fails to distinguish this as a risk primarily for users of cryosaunas.
Potential users should know before the first session of the WBC that cryotherapy is a kind of support (pre-treatment) for therapy or physical exercise. It is provided, for example, before rehabilitation procedures, in the case of medical indications, or as part of intensive training for athletes. Considering cryotherapy as a separate, autonomous treatment can provide users with misleading impressions about WBC results.
There are currently three types of WBC devices available on the market, but only two that are available to commercial users. In Europe, facilities mainly use classic cryochambers whereas the US market features mostly cryosaunas. The third option, cryochambers with cooling retention effects, is not available outside Poland.
The classic cryochamber (or Wroclaw-type) consists of two rooms, the pre- and main chamber. The operational temperatures of pre- and main chambers are -60 and -120°C, respectively, and are achieved by the evaporation of liquid nitrogen inside two or more heat exchangers located in both chambers. The unit exposes a user’s entire body, including head, to cold air cooled down by a convective heat transfer process.
Users of this device are never in direct contact with the LN2, a point the FDA muddies in its definition though a vague statement about freezing temperatures generated by liquid nitrogen. The organization also fails to stress that from a safety perspective, lack of direct contact between the user and cooling medium, particularly a cryogenic one, is a significant safety feature that distinguishes classic cryochambers from cryosaunas.
Cryosaunas are individual-sized can-like enclosures that are open at the top. Despite its popularity, a three-minute session in a cryosauna, or so-called “freezing tank,” is not a representative example of WBC treatment or devices. A user’s torso and legs are enclosed in the device and exposed to cold vapor of liquid nitrogen.
Regarding safety, the operational risk of cryosaunas is evident and the consequences of an accident or human error easy to predict. Indeed, the risk created by a cryosauna filled with cold nitrogen vapor (with its user in direct contact with an atmosphere of near zero O2 content) is incomparably higher than the risk of a cooling medium being released inside a classic cryochamber due to improper welding, pipe or heat exchange leakage, etc.
Moreover, the potential risk of decreasing oxygen content in a closed room with a WBC device in operation only occurs in the case of cryosauna operation. Such an effect will never occur during the standard operation of a classic cryochamber.