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Why is Hyperbaric a Medical Device

Why is hyper­bar­ic med­ical device?

A hyper­bar­ic cham­ber is a pres­sure cham­ber that increas­es air pres­sure. High­er pres­sures pro­por­tion­al­ly increase the amount of gas, espe­cial­ly oxy­gen dis­solved in the body. 

Hyper­bar­ic cham­bers mod­u­late both nitro­gen and oxy­gen dis­solved in the body.

Hyper­bar­ic cham­bers were orig­i­nal­ly used to enable divers to slow­ly release nitro­gen absorbed by body tis­sues dur­ing stays in high pres­sure nitro­gen-rich envi­ron­ments . Slow decom­pres­sion enables divers to slow­ly release dis­solved nitro­gen to avoid or treat the bends.

Dur­ing nitro­gen decom­pres­sion, divers not­ed that extra oxy­gen helped heal­ing and recov­ery from inci­den­tal con­di­tions and injuries. 

Oxygen Partial Pressure

NITROX, an air mix­ture that uses extra oxy­gen to dis­place nitro­gen, enables divers to dive deep­er and longer with­out decom­pres­sion.

Div­ing com­bines the exer­cise of swim­ming, ele­vat­ed oxy­gen pres­sure from com­pres­sion from water depth often with oxy­gen boost­ed by breath­ing NITROX. This process increas­es oxy­gen par­tial pres­sure in the body sev­er­al times above nor­mal. 

It has a long his­to­ry of safe­ty. Divers have long observed that div­ing with NITROX often cre­ates sur­pris­ing health ben­e­fits from dra­mat­i­cal­ly increased oxy­gen par­tial pres­sure in the body for short peri­ods.

The div­ing com­mu­ni­ty first rec­og­nized health effects of stand-alone use of hyper­bar­ic cham­bers to increase body oxy­gen lev­els. This prompt­ed adop­tion of stand-alone use of hyper­bar­ic cham­bers as a med­ical ther­a­py. 

The effects of NITROX div­ing and hyper­bar­ic ther­a­py are sim­i­lar because both process­es tem­porar­i­ly increase the amount of oxy­gen dis­solved in tis­sue, one uses exer­cise under vari­able res­pi­ra­to­ry con­di­tions while the oth­er requires occu­pan­cy in a cham­ber of com­pressed gas. 

Div­ing remains a sport, form of exer­cise, while hyper­bar­ic treat­ment is a med­ical ther­a­py.

Hyperbaric chambers are pressure capsules

The exis­tence and accep­tance of NITROX as a breath­ing mix­ture illus­trates that oxy­gen par­tial pres­sure does not con­sti­tute the basis for reg­u­la­tion of hyper­bar­ic cham­bers as a med­ical device. 

The main rea­son for reg­u­la­tion of hyper­bar­ic devices appears to be that their stand­alone use is intend­ed as a treat­ment for 14 accept­ed con­di­tions.

Excerpt­ed from: Mayo Clin­ic Hyper­bar­ic oxy­gen ther­a­py is used to treat sev­er­al med­ical con­di­tions. And med­ical insti­tu­tions use it in dif­fer­ent ways. Your doc­tor may sug­gest hyper­bar­ic oxy­gen ther­a­py if you have one of the fol­low­ing con­di­tions:

  • Ane­mia, severe
  • Brain abscess
  • Bub­bles of air in your blood ves­sels (arte­r­i­al gas embolism)
  • Burn
  • Decom­pres­sion sick­ness
  • Car­bon monox­ide poi­son­ing
  • Crush­ing injury
  • Deaf­ness, sud­den
  • Gan­grene
  • Infec­tion of skin or bone that caus­es tis­sue death
  • Non­heal­ing wounds, such as a dia­bet­ic foot ulcer
  • Radi­a­tion injury
  • Skin graft or skin flap at risk of tis­sue death
  • Vision loss, sud­den and pain­less

Pressure Chamber Effects & Risks:

Hyper­bar­ic cham­bers were adopt­ed for health sup­port.

Most risks from Hyper­bar­ic cham­bers stem from mechan­i­cal pres­sure effects on the body. 

The human body is most­ly water except for the inner ear and the lungs are air cham­bers. Gas in these com­part­ments expands and con­tracts as pres­sure changes.

When pres­sure changes, air must enter or escape to adjust. 

Too rapid air pres­sure change cause injury as these com­part­ments under or over-inflate.

When air pres­sure changes, more rapid­ly than these com­part­ments adjust, injury occurs.

These effects are well known. Diver’s know not to ascend while hold­ing breath, to avoid lung injury, or descend too rapid­ly to avoid ear injury. 

Ear injury may occur when exter­nal air pres­sure drops more quick­ly than air can escape. Sim­i­lar­ly, hold­ing the breath dur­ing rapid depres­sur­iza­tion, like when a scu­ba div­er ascends from depth, can also occur with a rapid hyper­bar­ic depres­sur­iza­tion while hold­ing the breath.

Hold­ing your breath while result­ing in Rapid air pres­sure changes may cause injury.

Pressure Swing Equalization on the ears

When you gain alti­tude, your ears pop because the air inside your inner ear expands and must escape to avoid over­pres­sure in the inner ear com­part­ment. 

When you lose alti­tude, the air inside your inner ear com­part­ment shrinks, so our body must open the eustachi­an tube add more to refill the cham­ber. 

If your body can­not equal­ize pres­sure as fast as the pres­sure changes, dis­com­fort and injury may occur. 

Dur­ing nor­mal oper­a­tion hyper­bar­ic cham­ber pres­sure changes slow­ly to allow the occu­pant to equal­ize air pres­sure in the ears. This can cause dis­com­fort or injury if it hap­pens too fast. 

Risk of Ear Injury for different types of chambers

One rea­son that hyper­bar­ic treat­ment is a med­ical treat­ment because the rate of pres­sure change must be reg­u­lat­ed to avoid injury and dis­com­fort.

The rate of pres­sure change must be man­aged dur­ing both pres­sur­iza­tion and depres­sur­iza­tion for the safe­ty and com­fort of the occu­pant.

Med­ical and mil­i­tary hyper­bar­ic cham­bers use heavy-duty mate­ri­als to min­i­mize the risk of injury from rapid depres­sur­iza­tion from mate­r­i­al fail­ure high pres­sures over 2 atmos­pheres. A depres­sur­iza­tion fail­ure could cause a sig­nif­i­cant injury.

Portable flex­i­ble cham­bers, made of fab­ric and plas­tic, are lim­it­ed to low pres­sure, 1.4 Atmos­pheres, because a loss of .4 atmos­pheres is only like­ly to result in dis­com­fort and mild injury. 

Captivity and Claustrophobia

Phys­i­cal use of a hyper­bar­ic cham­ber has both dis­com­fort and risk:

  • Pres­sure increas­es tem­per­a­ture and may be uncom­fort­able for users intol­er­ant of heat;
  • Move­ment is restrict­ed due to small size;
  • Suf­fo­ca­tion may occur in a pow­er fail­ure for users unable to self escape;
  • Use is tedious. Dwell times tend to be long 1 – 2 hours per treat­ment, with many treat­ments required;
  • Pan­ic is pos­si­ble for users sub­ject to claus­tro­pho­bia.

This com­bi­na­tion of fac­tors con­tribute to the rea­sons why hyper­bar­ic is a med­ical­ly reg­u­lat­ed treat­ment and requires med­ical super­vi­sion.

Blood Gas Effects

Blood gasses con­trol res­pi­ra­tion.

We inhale when Car­bon Diox­ide accu­mu­lates in the blood as Car­bon­ic Acid. Inhale cre­ates a vac­u­um in the lungs which draws Car­bon Diox­ide through the alve­o­lar mem­brane to neu­tral­ize car­bon­ic acid.

Exhale pres­sur­izes the air in the lungs, 21% oxy­gen, to force oxy­gen through the alve­o­lar mem­brane to oxy­genate Red Blood Cells and blood plas­ma.

Car­bon Diox­ide as car­bon­ic acid is the pri­ma­ry trig­ger for res­pi­ra­tion, and oxy­gen deple­tion is a sec­ondary res­pi­ra­to­ry trig­ger.

Con­cern for dys­func­tion in res­pi­ra­to­ry dri­ve result­ing from unan­tic­i­pat­ed devi­a­tions in blood gas con­cen­tra­tions while in a cap­tive pres­sur­ized envi­ron­ment cre­ates an ele­ment of risk for patients with res­pi­ra­to­ry dis­or­ders result­ing in var­i­ous con­traindi­ca­tions for hyper­bar­ic ther­a­py. 

Oxygen Toxicity Effects

Oxy­gen tox­i­c­i­ty has been doc­u­ment­ed to occur very high oxy­gen par­tial pres­sure envi­ron­ments and for infants. There are three dif­fer­ent oxy­gen tox­i­c­i­ty effects affect­ing dif­fer­ent organs:

Data Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4925834/

Cen­tral Ner­vous Sys­tem3 ATM100%>6 min­utes
Lung1 ATM50%Over 10 hours
Ocu­lar (eye)1 ATM>60% (infants)

The con­di­tions for oxy­gen tox­i­c­i­ty gen­er­al­ly do not occur in hyper­bar­ic cham­bers except pos­si­bly with infants. Nor­mal admin­is­tra­tion lim­its keep oxy­gen expo­sure with­in well estab­lished safe lim­its.


Hyper­bar­ic ther­a­py is reg­u­lat­ed as a med­ical treat­ment because of four user risk ele­ments:

  1. Ear injury to the user from rapid pres­sure swings;
  2. Anx­i­ety or pan­ic from claus­tro­pho­bia dur­ing con­fined cap­tiv­i­ty;
  3. Risk of suf­fo­ca­tion from air­flow loss dur­ing pow­er fail­ure when a user can­not self-escape;
  4. Oxy­gen Tox­i­c­i­ty is only pos­si­ble with 4x hyper­bar­ic cham­bers or with infants;
  5. Sec­ondary con­traindi­ca­tions from res­pi­ra­to­ry sys­tem dys­func­tion or drugs that increase oxida­tive stress, cer­tain antibi­otics and chemother­a­peu­tic agents.

All of these fac­tors com­bine to cre­ate a small user risk. This risk is mit­i­gat­ed by dis­trib­ut­ing hyper­bar­ic ther­a­py and ther­a­py devices by pre­scrip­tion. 

Hyper­bar­ic cham­bers have a many year his­to­ry of safe­ty with very few report­ed adverse events or effects, and many report­ed ben­e­fits.

Updated on August 27, 2019

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