Long Term Oxygen Therapy (LTOT) has been an option for treating patients in need of oxygen therapy for over 50 years. Cylinders were the first therapy option for LTOT since they were available in hospitals that did not have a piped oxygen system. After cylinders were delivered to the hospital by the gas delivery company, they would be transferred to the home with the patient. Liquid oxygen (LOX) soon became an option for efficient delivery of bulk oxygen to a hospital, and shortly thereafter, in 1965, a smaller system was introduced and made available for use inside the home.Cylinder Transfilling
Portable oxygen was first made available via the use of smaller cylinders. These systems usually weighed 20 lbs and required the use of a cart. Subsequently, the LOX portable offered a lighter option with more operating range. LOX portables weighed approximately 8 – 10 pounds and could be carried by the patient. Carts were again available for patients that could not carry that amount of weight. While these were great strides, weight and range-of-use are big issues for most patients. Pulmonary diseases are debilitating and any additional work related to moving an oxygen system often countered the benefit of having portable oxygen to begin with.
The first home LOX system.
In these early years, and up until the late 1970’s and early 80’s, patients were prescribed LTOT as a last resort to combat their disease. However, this would change after the results of two significant studies were published. The most significant research related to LTOT occurred in the late 1970’s with the British Medical Research Council (MRC) and the North American Nocturnal Oxygen Therapy Trials (NOTT). Both of these studies were conducted on a significantly large number of patients over several years. The findings of the MRC were that patients with 12 hours of oxygen therapy a day had better survival rates than patients who did not use oxygen at all. The NOTT study followed that with the discovery that patients on close to 24 hours of LTOT had a better survival rates than patients on 12 hours. In addition to this conclusion, looking at the NOTT study data from another perspective revealed that patients who were ambulatory during the study had an even higher survival rate than the more stationary patients. These ambulatory patients also had reduced hospitalizations and shorter lengths of stay when they were hospitalized. This data suggested that patients should be encouraged to be as active as possible while still maintaining proper oxygen saturation levels. As a result of these landmark and groundbreaking studies, early prescription of LTOT became the standard of care as opposed to the “last resort”.
CRYO2 Demand Oxygen Controller, circa 1984
Now that LTOT in the home setting was becoming more and more prevalent, the next logical step was to maximize the use of available oxygen to a patient. In 1984 the first intermittent flow oxygen delivery device, CRYO/2’s Demand Oxygen Controller, was introduced to the home care market. Chad Therapeutics followed shortly thereafter with the Oxymatic conserver. Appreciating the fact that oxygen delivered when the patient was exhaling is wasteful, these oxygen conserving devices (OCDs) sensed the patient’s inspiratory effort and delivered a dose of oxygen only during inhalation. Yet neither the Demand Oxygen Controller or Oxymatic devices found mainstream acceptance until the mid-1990s.
Since then, a combination of improved designs and ease of use, as well as extreme cost pressure from reimbursement sources, has moved these systems from a curiosity to an essential part of ambulatory oxygen therapy. OCDs are found not only as standalone components to be used with stationary oxygen systems, but also integrated with:
  • Regulators for use with high-pressure cylinders
  • Small, lightweight liquid oxygen systems
  • Portable oxygen concentrators
Today's OCDs enable freedom.
Originally conceived as simply a means to extend the life of a source of oxygen, OCD technology has changed the face of oxygen therapy. OCDs have enabled many patients to be shifted from older, heavier liquid oxygen systems to gaseous systems of similar weight and range. The development of OCD technology has allowed the creation of four-pound liquid oxygen systems that have up to 8 hours of use time. In addition, OCD technology has enabled the long-standing dream of a portable oxygen concentrator (POC) to become a reality. In the last three years alone, four new POCs have been introduced to the LTOT market.
There is no doubt that devices that efficiently use available oxygen are here to stay. While early systems were quite crude and bulky, the technology has evolved to be reliable, compact and easy for a patient to use. Patients are no longer limited to staying in and around their homes; the development of OCDs and the resulting technological advances have enabled them to live their lives as normally as possible.

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Ryan Diesem, BS, RRT, RRT-NPS



Email: rdiesem(at)inspiredrc.com