Respiratory therapists-also known as respiratory care practitioners-evaluate, treat, and care for patients with breathing or other cardiopulmonary disorders. Practicing under the direction of a physician, respiratory therapists assume primary responsibility for all respiratory care therapeutic treatments and diagnostic procedures, including the supervision of respiratory therapy technicians. Respiratory therapy technicians follow specific, well-defined respiratory care procedures under the direction of respiratory therapists and physicians. Respiratory therapists will consult with physicians and other health care staff to help develop and modify individual patient care plans. Respiratory therapists also provide complex therapy requiring considerable independent judgment, such as caring for patients on life support in intensive-care units of hospitals.

Respiratory therapists evaluate and treat all types of patients, ranging from premature infants whose lungs are not fully developed to elderly people whose lungs are diseased. Respiratory therapists provide temporary relief to patients with chronic asthma or emphysema, as well as emergency care to patients who are victims of a heart attack, stroke, drowning, or shock. To evaluate patients, respiratory therapists interview them, perform limited physical examinations, and conduct diagnostic tests. For example, respiratory therapists test patients' breathing capacity (Spirometry, Lung Volumes, Diffusion Capacity) and determine the concentration of oxygen and other gases in patients' blood. They also measure patients' pH, which indicates the acidity or alkalinity of the blood. To analyze oxygen, carbon dioxide, and pH levels, therapists draw an arterial blood sample, place it in a blood gas analyzer, and then may make treatment decisions.

To treat patients, respiratory therapists use oxygen or oxygen mixtures, chest physiotherapy, and aerosol medications. When a patient has difficulty getting enough oxygen into his or her blood, therapists increase the patients' concentration of oxygen by placing an oxygen mask , nasal cannula or other oxygen delivery devices on the patient and set the oxygen flow to maintain an appropriate oxygen saturation in the blood. Therapists also connect patients who cannot breathe on their own to ventilators that deliver pressurized gases into the lungs. The therapists insert a tube into the patients' trachea, or windpipe (intubation); connect the tube to the ventilator; and make appropriate settings for air entry into the patients' lungs. Therapists perform regular assessments of patients and equipment. If the patient appears to be having difficulty breathing or if the oxygen, carbon dioxide, or pH level of the blood is abnormal, therapists change the ventilator setting accordingly or check the equipment for mechanical problems.

In home care, therapists teach patients and their families to use ventilators and other life-support systems. In addition, therapists visit patients several times a month to inspect and clean equipment and to ensure its proper use. Therapists also make emergency visits if equipment problems arise. Respiratory therapists perform chest physiotherapy on patients to remove mucus from their lungs and make it easier for them to breathe. Chest physiotherapy also helps patients suffering from lung diseases, such as cystic fibrosis, that cause mucus to collect in the lungs. Therapists place patients in positions that help drain mucus, and then vibrate the patients' rib cages and instruct the patients to cough.

Respiratory therapists also administer aerosols-liquid medications suspended in a gas that forms a mist which is inhaled-and teach patients how to inhale the aerosol properly to ensure its effectiveness. Other respiratory drugs such as inhalers are also administered by Respiratory therapists as per a physician's order.

In some hospitals, therapists perform tasks that fall outside their traditional role. Therapists' tasks are expanding into areas such as pulmonary rehabilitation, smoking cessation counseling, disease prevention, case management, and polysomnography-the diagnosis of breathing disorders during sleep, such as apnea. Respiratory therapists also increasingly treat critical care patients, either as part of surface and air transport teams or as part of rapid-response teams in hospitals.