For those who need it, supplemental oxygen is beneficial. There may be improvement in sleep, cognition (mental alertness and stamina), and mood. (2,3) Oxygen has also been found to prevent and improve heart failure (cor pulmonale) in people with severe pulmonary disease. (4) In 2 major randomized clinical trials, The British Medical Research Council Clinical Trial and The Nocturnal Oxygen Therapy Trial (NOTT), investigators were able to improve survival outcomes by using long term oxygen therapy in the treatment of patients with COPD and chronic stable hypoxemia. (3,5) Both of these studies found that using nocturnal oxygen therapy (NOT) and continuous oxygen therapy (COT) for at least 12-15 hours per day improved survival.
Oxygen is used in a variety of settings. Patients with pulmonary or cardiac disease who are hospitalized are often on supplemental oxygen during an acute phase of their illness. Oxygen may be delivered in Intensive Care Units via ventilators and on cardiac, pulmonary, general medicine, and surgical hospital units. Supplemental oxygen is used in skilled nursing facilities, in the home, and in the community. Consequently, physical therapists (PTs) will encounter patients requiring oxygen supplementation in a variety of work settings. As a result, it is imperative that physical therapists understand the proper use of oxygen and logistics regarding oxygen equipment.
The American Physical Therapy Association (APTA) recognizes therole physical therapists have in the administration and adjustment ofoxygen while treating various patient populations. (6) The APTA'sGuide to Physical Therapist Practice (2nd ed) delineates the physicaltherapist's scope of practice in the management of patients whorequire oxygen to improve ventilation and respiration/ gas exchange. TheAPTA is unaware of any regulations that prohibit the use of oxygen forpatient management if it is prescribed and if parameters set by thephysician are maintained. (7) Physicians specify oxygen flow rates intheir orders. Any deviation in the prescribed dosage requires an updatedorder from the physician. The Food and Drug Administration (FDA) of theUnited States Department of Health and Human Services states that"medical oxygen is defined as a prescription drug which requires aprescription in order to be dispensed except ... for emergencyuse." (8)
Within the APTA's Guide, supplemental oxygen is listed as a procedural intervention within the scope of physical therapist practice under Prescription, Application, and, as appropriate, Fabrication of Devices and Equipment (supportive device) to improve ventilation and respiration/gas exchange. (6) The APTA has a position statement adopted by the House of Delegates which states:
"PT patient/client management integrates an understanding of a patient's/client's prescription and nonprescription medication regimen with consideration of its impact upon health, impairments, functional limitations, and disabilities. The administration and storage of medications used for physical therapy interventions is also a component of patient/client management and thus within the scope of PT practice. Physical therapy interventions that may require the concomitant use of medications include, but are not limited to, agents that facilitate airway clearance and/or ventilation and respiration." (9)
Each individual State Board of Physical Therapy may have official statements or opinions regarding the administration of oxygen in addition to the professional organization's statement.
The Increasing Need for Supplemental Oxygen
In 2006, 12.1 million United States adults aged 18 years and older were estimated to have COPD. (10) However, the National Health and Nutrition Examination Surveys (NHAMES) estimates that approximately 24 million adults in the United States have evidence of impaired lung function, indicating that COPD is under diagnosed. (11) COPD is the 4th most common cause of death in the United States and ranges from 5th to 14th worldwide. Of the 10 most common causes of death in the United States, COPD is the only disease with an increasing mortality rate. Mortality from COPD is increasing most rapidly in those areas of the world with the greatest tobacco use, and among women. (12)
The population in the United States is aging. Considering that thefirst of the "baby boomers" are reaching 60+ years of age andthat the fastest growing population in the United States is over 85years of age, (13) physical therapists must be prepared to treat theolder population, be knowledgeable about their multiple medicalproblems, and be competent in using a range of modalities, such assupplemental oxygen, to augment improvement in their functional ability.Supplemental oxygen may be required by people of varied ages and withvaried types of pulmonary, cardiac and blood diseases such as COPD, IPF,congestive heart failure (CHF), cystic fibrosis (CF), and sickle cellanemia.
A thorough knowledge of oxygen equipment is imperative for the physical therapist. Pulse oximetry is a noninvasive method of photoelectrically determining the oxyhemoglobin saturation of arterial blood. (14) A sensor is placed on a thin part of the patient's anatomy such as a fingertip or earlobe and a light containing both red and infrared wavelengths is passed through the skin to the small arteries. A microprocessor compares the signals received and calculates the degree of oxyhemoglobin saturation based on the intensity of transmitted light. (14) Larger, stationery oximetry monitors are typically used in intensive care units. Small, hand-held, portable monitors are easily clipped to the distal end of a finger or attached to the earlobe by an earlobe clip.
A variety of oxygen delivery devices may be used to administer oxygen to the patient. The most common is the nasal cannula which can provide oxygen flows from 0.25 to 6 liters per minute (LPM). An oxymizer delivery device is a nasal cannula with a reservoir incorporated into the tubing mechanism. (15) During exhalation, the reservoir fills with oxygen and is available to the patient upon the next inhalation, essentially providing equivalent saturations at lower flow rates. Manufacturers state that an oxygen savings of approximately 75% may be obtained by using the oxymizer and lower flow rates provide greater patient comfort. (15)
Additionally, oxygen masks are used to deliver even higher concentrations of supplemental oxygen. When pulmonary patients exercise, higher percentages (Fi[O.sub.2]) of oxygen are needed to meet the demand of working muscles and to maintain oxygen saturation levels within prescribed limits (usually 88% to 90%). (14) Two types of oxygen masks may be used during exercise with pulmonary patients. The venturi mask uses a mechanical opening which increases the rate at which the oxygen flows into the mask (commonly 24% to 50%). A partial rebreather mask has a reservoir bag attached and physical therapy sports medicine delivers between 70% to > 80% of oxygen. A non rebreather mask also incorporates a reservoir bag, but can deliver up to 100% oxygen. Flows between 7 and 10 LPM are required to keep the reservoir bag inflated at all times. (16) Less conspicuous forms of oxygen delivery are available for low to moderate oxygen flow patients. Transtracheal oxygen delivery consists of a small catheter being surgically placed into the trachea through the second and third tracheal rings. Transtracheal is well accepted by patients and delivers oxygen more efficiently than a nasal cannula. Because oxygen is delivered directly into the trachea, approximately 50% less oxygen is needed. (16) Other more aesthetically appealing methods of oxygen delivery exist such as small oxygen tubes being imbedded into eyeglass frames. (17)
Physical therapists must be well-informed about the varied pathologies that may lead to the need for supplemental oxygen. A broad spectrum of pulmonary, cardiac, and blood abnormalities warrant the use of supplemental oxygen. Accordingly, PTs should be able to choose the proper equipment for individual patients with various diagnoses by using cardiopulmonary evaluation techniques, monitoring equipment, and evidence based practice. Oxygen flow rates may require titration depending on the level of physical activity (rest versus exercise versus sleep). In addition, different diagnoses, due to their pathophysiology, require lower or higher oxygen flow rates depending on the patient's activity level.
The physician normally sets the flow rate for sleep and rest, but with exercise, the PT is instrumental in determining the proper oxygen flow rate needed. It is important to communicate with the physician regarding oxygen requirements during exercise. With this knowledge, the physician can make crucial decisions concerning the patient's medication effectiveness, dosage, stability of the disease, and surgical options.
A few basic concepts of oxygen delivery, functional ability, and biomechanics are necessary to guide the patient, physician, and oxygen vendor in meeting a patient's specific equipment needs. There are essentially 3 types of oxygen delivery systems. First, an oxygen concentrator has the ability to deliver oxygen up to a level of 5 LPM. It is a device that separates oxygen from room air. There are stationary models, under electrical power, that are suitable to use around the house and during sleep. Different lengths of oxygen tubing are available to accommodate movement from room to room. More recently, portable oxygen concentrators have become available that allow a patient to move in and out of the house and community under battery power. These units are much smaller, sit in a small 2 wheeled stroller, and are pulled along behind the patient similar to a rolling suitcase. These units are appropriate for patients on oxygen flows, at rest and with exercise, between 1 and 5 LPM. The oxygen production is only limited by the life of the portable battery charge when away from an electrical outlet. (18)
Second, compressed gas oxygen tanks are available in a range of sizes for portable use. These are also mobile on a 2 wheeled stroller or in a pack that can be supported over the shoulder. More recently, these tanks are being manufactured from aluminum rather than iron or other heavy metals, which is much lighter-weight and manageable for small frame individuals. These tanks are used with an oxygen flow regulator which attaches to the top of the cylinder. The regulator must be manually changed to a full tank once the tank is emptied. There are 2 types of regulators: continuous flow and pulsed dose oxygen conservers. The continuous flow delivers oxygen during the full respiratory cycle (inspiration and expiration). Variations of these regulators will allow flow rates between 0.25 and 25 LPM. At a flow rate of 2 LPM, one E cylinder tank will last approximately 4-5 hours. (18) The oxygen conserver regulator delivers oxygen during inhalation only (demand system), or at pre-set intervals (pulsed system); thus, saving on the amount of oxygen used over time. (19) These regulators are typically used with smaller compressed gas tanks and deliver oxygen for variable lengths of time dependent on the interval and volume of oxygen puffs and the size of the tank. An E cylinder tank with an oxygen conserver regulator can provide oxygen delivery > 15 hours at a flow rate of 2 LPM. (18) Depending on the pathology and the individual oxygen requirements, the PT must decide which compressed gas oxygen tank and regulator will best meet the patient's needs. Ambulatory oxygen systems are defined as those weighing less than 10 lbs. Many patients find 8.5 lbs. a practical weight to carry, but smaller framed patients may be better served with a unit in the < 5 lb. range. (20) Biomechanical and psychomotor factors to be considered are that some patients have difficulty with the manual task of changing regulators due to weakness of the hands, joint deformities, pain, or cognitive deficits. Other patients who have osteoporosis or back pain may have difficulty lifting compressed gas tanks in and out of a car due to their weight and awkward shape. Still other patients with gait abnormalities have difficulty maneuvering tanks in strollers over curbs, steps, and through doors. (21)
A third type of oxygen delivery is a liquid oxygen system. A large stationary tank is typically delivered to the patient's home. The patient is also provided with a portable tank that is refilled off of the stationary tank. Portable liquid tanks come in a variety of sizes and weights. The largest liquid system has the capability of a 15 LPM flow rate and can be carried either on the shoulder, in a backpack, or in a 2 wheeled stroller. One of the smallest units has a maximum of 4 LPM flow rate, pulsed or continuous, and may be carried by the small handle on the unit or worn around the waist in a waist pack. (18)
For Medicare Part B patients, supplemental oxygen is supplied by a Durable Medical Equipment (DME) carrier. The physician must complete and sign a Certificate of Medical Necessity (CMN) describing the patient's need for oxygen, arterial blood gases or oxygen saturation levels, prescribed flow rate, and medical diagnosis. If a specific type of portable system or flow rate is required for a patient to participate in a full range of physical activities, it must be noted on the CMN. Otherwise, because DME suppliers are reimbursed at a fixed rate, regardless of the oxygen system they provide the patient, suppliers realize a larger profit by providing less costly systems. A supplier cannot change a physician's prescription; therefore, it must be filled as written. (22)
In conclusion, it is not uncommon for PTs to treat a variety of patients who require supplemental oxygen, either on an in-patient or out-patient basis. It is within the physical therapy scope of practice to administer and adjust oxygen according to the physician's prescription. The physical therapist must have a thorough knowledge of oxygen equipment and how to use various devices to meet the physiological and biomechanical needs of the patient.
(1.) American Lung Association. Fact Sheet: Oxygen. Nov 2004. Available at www.lungusa.org. Accessed December, 2007.
(2.) Krop HD, Block AJ, Cohen E. Neuropsychologic effects of continuous oxygen therapy in chronic obstructive pulmonary disease. Chest. 1973;64:317-322.
(3.) Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease: a clinical trial. Nocturnal Oxygen Therapy Trial Group. Ann Intern Med. 1980;93:391-398.
(4.) Petty TL, Finigan MM. Clinical evaluation of prolonged ambulatory oxygen therapy in chronic airway obstruction. Am J Med. 1968;45:242-252.
(5.) Long term domiciliary oxygen therapy in chronic hypoxic cor pulmonale complicating chronic bronchitis and emphysema. Report of the Medical Research Council Working Party. Lancet. 1981;317:681-686.
(6.) American Physical Therapy Association. Guide to Physical Therapist Practice. 2nd ed. Alexandria, Va; 2003.
(7.) American Physical Therapy Association. Oxygen Administration During Physical Therapy. Available at: www.apta.org. Accessed December 2007.
(8.) Human drug CGMP Notes. 4(4), Dec 1996. Available at: www.fda.gov. Accessed December 2007.
(9.) Pharmacology in Physical Therapist Practice HOD P06-04-14-14 (Program 32). Available at www.apta.org. Accessed December 2007.
(10.) American Lung Association. Trends in COPD: Morbidity and Mortality. Dec 2007. Available at www.lungusa.org. Accessed February, 2008.
(11.) Centers for Disease Control and Prevention. Chronic Obstructive Pulmonary Disease Surveillance-United States, 1971-2000. Available at: www.usa.gov. Accessed December 2007.
(12.) Hartert TV, Gabb MG: The National and Global Impact of COPD. Johns Hopkins ADV STUD MED. 2004;4(10A):S738-743.
(13.) Administration on Aging. Aging into the 21st Century. Available at: www.aoa.gov. Accessed March 2008.
(14.) Sadowsky HS. Pulmonary diagnostic tests and procedures. In: Hillegass EA, Sadowsky HS. Essentials of Cardiopulmonary Physical Therapy. 2nd ed. Philadelphia, Pa: W. B. Saunders; 2001:421-449.
(15.) Oxymizer Disposable Oxygen-Conserving Devices. Available at: www.chadtherapeutics.com. Accessed March 2008.
(16.) Frownfelter D, Baskin MW. Respiratory care practice review. In: Frownfelter D, Dean E. Cardiovascular and Pulmonary Physical Therapy: Evidence and Practice, 4th ed. St. Louis, Mo: Mosby; 2006:759-771.
(17.) Hoffman LA, Wesmiller SW. Home oxygen: transtracheal and other options. Am J Nurs. 1988;88:464469.
(18.) Petty TL. Guide to prescribing home oxygen: Types of home oxygen systems. National Lung Health Education Program (NLHEP). Available at: www.nlhep.org. Accessed December 2007.
(19.) NLHEP. Conserving device technology. Available at: www.nlhep.org. Accessed December 2007.
(20.) NLHEP. Keys to successful treatment. Available at: www.nlhep.org. Accessed December 2007.
(21.) NLHEP. Patient considerations in selecting equipment. Available at: www.nlhep.org. Accessed December 2007.
(22.) NLHEP. Costs and reimbursement. Available at: www. nlhep.org. Accessed December 2007.
Rebecca H. Crouch, PT, MS, CCS, FAACVPR Coordinator of Pulmonary Rehabilitation, Duke University Medical Center, Department of Physical Therapy