Hyperbaric means “relating to, producing, operating, or occurring at pressures higher than normal atmospheric pressure.”  As early as the 1600s, practitioners varied atmospheric pressure in attempts to heal. Using a system of organ bellows, a British clergyman named Henshaw could adjust pressure within a sealed chamber called a domicilium . The simplistic principle behind its use was that acute conditions would respond to elevated atmospheric pressures, whereas chronic conditions would benefit from reduced pressure.
As time passed, air-compression devices evolved in appearance and function. It also was discovered that the use of compressed air could facilitate other methods. For example, a French surgeon named Fontaine created a mobile chamber that took advantage of a basic law of physics (Henry’s law), which states that the solubility of a gas in a liquid is proportional to the pressure of the gas over the solution, provided that no chemical reaction occurs. By raising the atmospheric pressure within the chamber, Fontaine was able to increase the amount of oxygen carried by the patient’s bloodstream during the administration of nitrous oxide anesthesia. This prevented blood oxygen levels from falling too low as typically happened with surgically acceptable depths of anesthesia .
In the early 1900s, Cunningham observed that patients with cardiovascular disease who dwelled at high altitudes fared less well than comparable patients living closer to sea level. Suspecting that altitude-dependent changes of atmospheric pressure were responsible, Cunningham hypothesized that raising pressure beyond a normobaric level would confer even greater benefit. He successfully treated a young colleague with influenza who was near death from lack of oxygen secondary to restricted lung function. With that success bolstering his confidence, he developed a cylindrical hyperbaric chamber approximately 3 meters in diameter by 27 meters in length, which could be used to treat many conditions .
Cunningham’s fortunes took another upturn following the recovery of a patient afflicted with kidney disease. Ascribing his dramatically improved health to hyperbaric therapy, the grateful patient built for Cunningham a chamber fit for a king. This chamber — built in Kansas City in 1921 — was a hollow steel ball of approximately 20 meters in diameter and equipped with a smoking lounge, dining facilities, rich carpeting, and private quarters .
As grand as it may have been, the largest and probably the most ostentatious hyperbaric chamber in history met an undignified end. Its continued survival depended on demonstrable successes. Cunningham postulated that anaerobic bacteria (bacteria preferring low oxygen environments) were responsible for cancers, high blood pressure, and many other conditions. Based on this, he predicted that all would resolve at elevated atmospheric pressures that increase blood oxygen levels. Unfortunately, medical authorities did not find the results compelling, and Cunningham’s hyperbaric “hospital” was closed and demolished for scrap metal.
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