Ancient Times

Humans have been concerned about the common problems of sickness, disease, old age, and death since primitive times. Early cultures developed herbal treatments for many diseases, and surgery may have been performed in Neolithic times. Physicians practiced medicine in ancient Mesopotamia, Egypt, India, and China.1,4,7 However, the foundation of modern Western medicine was laid in ancient Greece with the development of the Hippocratic Corpus.^1,4,7,8 This ancient collection of medical treatises is attributed to the “father of medicine,” Hippocrates, a Greek physician who lived during the fifth and fourth centuries bc.^1,7,8 Hippocratic medicine was based on four essential fluids, or “humors”—phlegm, blood, yellow bile, and black bile—and the four elements—earth (cold, dry), fire (hot, dry), water (cold, moist), and air (hot, moist). Diseases were thought to be humoral disorders caused by imbalances in these essential substances. Hippocrates believed there was an essential substance in air that was distributed to the body by the heart.¹ The Hippocratic Oath, which admonishes physicians to follow certain ethical principles, is given in a modern form to many medical students at graduation.^1,8

Aristotle (384-322 bc), a Greek philosopher and perhaps the first great biologist, believed that knowledge could be gained through careful observation.1,8 Aristotle made many scientific observations, including observations obtained by performing experiments on animals. Erasistratus (about 330-240 bc), regarded by some as the founder of the science of physiology, developed a pneumatic theory of respiration in Alexandria, Egypt, in which air (“pneuma”) entered the lungs and was transferred to the heart.^1,7 Galen (130-199 ad) was an anatomist in Asia Minor whose comprehensive work dominated medical thinking for centuries.^1,6,7 Galen also believed that inspired air contained a vital substance that somehow charged the blood through the heart.¹

Middle Ages, the Renaissance, and the Enlightenment Period

The Romans carried on the Greek traditions in philosophy, science, and medicine. With the fall of the Western Roman Empire in 476 ad, many Greek and Roman texts were lost and Europe entered a period during which there were few advances in science or medicine. In the seventh century ad, the Arabians conquered Persia, where they found and preserved many of the works of the ancient Greeks, including the works of Hippocrates, Aristotle, and Galen.1,7 A Golden Age of Arabian medicine (850-1050 ad) followed.

An intellectual rebirth in Europe began in the twelfth century.1,7 Medieval universities were formed, and contact with the Arabs in Spain and Sicily reintroduced ancient Greek and Roman texts. Magnus (1192-1280) studied the works of Aristotle and made many observations related to astronomy, botany, chemistry, zoology, and physiology. The Renaissance (1450-1600) ushered in a period of scientific, artistic, and medical advances. da Vinci (1452-1519) studied human anatomy, determined that subatmospheric interpleural pressures inflated the lungs, and observed that fire consumed a vital substance in air without which animals could not live.^1,4 Vesalius (1514-1564), considered to be the founder of the modern field of human anatomy, performed human dissections and experimented with resuscitation.¹ In 1543, the date commonly given as the start of the modern Scientific Revolution, Copernicus observed that the Earth orbited the sun.⁸ Before this time, it had been accepted that the Earth was the center of the universe.

The seventeenth century was a time of great advances in science. Accomplished scientists from this period include Kepler, Bacon, Galileo, Pascal, Hooke, and Newton. In 1628, Harvey fully described the circulatory system.4,8 In 1662, the chemist Boyle published what is now known as Boyle’s law, governing the relationship between gas volume and pressure.⁸ Torricelli invented the barometer in 1650, and Pascal showed that atmospheric pressure decreases with altitude.^1,4 van Leeuwenhoek (1632-1723), known as the “father of microbiology,” improved the microscope and was the first to observe and describe single-celled organisms, which he called “animalcules.”⁷

The eighteenth-century Enlightenment Period brought further advances in the sciences. In 1754, Black described the properties of carbon dioxide, although the discovery of carbon dioxide should be credited to van Helmont, whose work occurred about 100 years earlier.¹ In 1774, Priestley described his discovery of oxygen, which he called “dephlogisticated air.”^1,4 Before 1773, Scheele performed the laboratory synthesis of oxygen, which he called “fire air”; a general description of his discovery appeared in 1774, and a more thorough description appeared in 1777.^1,4 Shortly after the discovery of oxygen, Spallazani worked out the relationship between the consumption of oxygen and tissue respiration.¹ In 1787, Charles described the relationship between gas temperature and volume now known as Charles’ law.⁸ In experiments performed between 1775 and 1794, Lavoisier showed that oxygen was absorbed by the lungs and that carbon dioxide and water were exhaled.^1,4 In 1798, Beddoes began using oxygen to treat various conditions at his Pneumatic Institute in Bristol.^1,4

Nineteenth and Early Twentieth Centuries

During the nineteenth century, important advances were made in physics and chemistry related to respiratory physiology. Dalton described his law of partial pressures for a gas mixture in 1801 and his atomic theory in 1808.⁸ Young in 1805 and de LaPlace in 1806 described the relationship between pressure and surface tension in fluid droplets.⁸ Gay-Lussac described the relationship between gas pressure and temperature in 1808, and in 1811, Avogadro stated that equal volumes of gases at the same temperature and pressure contain the same number of molecules.^1,8 In 1831, Graham described his law of diffusion for gases (Graham’s law).⁸

In 1865, Pasteur advanced his “germ theory” of disease, which held that many diseases are caused by microorganisms.⁸ Medical advances during this time included the invention of the spirometer and ether anesthesia in 1846, antiseptic techniques in 1865, and vaccines in the 1880s.^1,4,7 Koch, a pioneer in bacteriology, discovered the tubercle bacillus, which causes tuberculosis, in 1882 and the vibrio bacterium, which causes cholera, in 1883.⁷ Respiratory physiology also progressed with the measurement in 1837 of blood oxygen and carbon dioxide content, the description around 1880 of the respiratory quotient, demonstration in 1885 that carbon dioxide is the major stimulant for breathing, and demonstration in 1878 that oxygen partial pressure and blood oxygen content were related.^1,4,9 In 1895, Roentgen discovered the x-ray, and the modern field of radiologic imaging sciences was born.⁸ Pioneering respiratory physiologists of the early twentieth century described oxygen diffusion, oxygen and carbon dioxide transport, the oxyhemoglobin dissociation curve, acid-base balance, and the mechanics of breathing and made other important advances in respiratory physiology (see Table 1-2).

Oxygen Therapy

Although the therapeutic administration of oxygen first occurred in 1798, and Bert showed that lack of oxygen caused hyperventilation in 1878, the physiologic basis and indications for oxygen therapy were not well understood until the twentieth century.1,4 Large-scale production of oxygen was developed by von Linde in 1907. The use of a nasal catheter for oxygen administration was introduced by Lane in the same year.^1,4 Oxygen tents were in use in 1910, and an oxygen mask was used to treat combat gas–induced pulmonary edema in 1918.¹ In 1920, Hill developed an oxygen tent to treat leg ulcers, and in 1926, Barach introduced a sophisticated oxygen tent for clinical use. Oxygen chambers and whole oxygen rooms were designed.^1,4 In 1938, a meter mask was developed by Barach to administer dilute oxygen.^1,4 The BLB mask (named for Boothby, Lovelace, and Bulbulian) to administer 80% to 100% oxygen to pilots was introduced during World War II and later used on patients.^1,4 By the 1940s, oxygen was widely prescribed in hospitals, although there was still no good way to measure blood oxygen levels routinely until the mid-1960s, with the introduction of the Clark electrode, followed by the clinical use of the ear oximeter in 1974 and the pulse oximeter in the 1980s.^1,4,5 The Campbell Ventimask, which allowed the administration of 24%, 28%, 35%, or 40% oxygen, was introduced in 1960, and modern versions of the nasal cannula, simple oxygen mask, partial rebreathing mask, and nonrebreathing mask were available by the late 1960s. Portable liquid oxygen systems for long-term oxygen therapy in the home were introduced in the 1970s, and the oxygen concentrator soon followed. Oxygen-conserving devices, including reservoir cannulas, demand pulse oxygen systems, and transtracheal oxygen catheters, were introduced in the 1980s.

The 2000s saw further advances in home oxygen therapy equipment with the introduction of oxygen concentrators used in conjunction with a pressure booster to allow for the transfilling of small, portable oxygen cylinders in the home. Smaller, lightweight portable oxygen concentrators were also introduced. Both of these advances have greatly enhanced the ability of patients receiving long-term oxygen therapy to ambulate beyond the confines of their home.

Aerosol Medications

Aerosol therapy is defined as the administration of liquid or powdered aerosol particles via inhalation to achieve a desired therapeutic effect. Bland aerosols (sterile water, saline solutions) or solutions containing pharmacologically active drugs may be administered. In 1802, the use of inhaled Datura leaf fumes, which contain atropine, to treat asthma was described.¹⁰ Early use of aerosol medications dates to 1910, when the first use of aerosolized epinephrine was reported. Later, other short-acting bronchodilators such as isoproterenol (1940), isoetharine (1951), metaproterenol (1961), albuterol sulfate (1980), and levalbuterol (2000) were introduced, primarily for the emergency treatment of acute asthma attacks.¹⁰ Oral and injectable steroids were first used in the treatment of asthma in the early 1950s, and the use of aerosolized steroids for the maintenance of patients with moderate to severe asthma began in the 1970s.¹⁰ Since that time, numerous medications have been designed for aerosol administration, including long-acting bronchodilators, mucolytics, antibiotics, and antiinflammatory agents. Along with newer respiratory drugs, newer delivery devices such as dry powder inhalers and innovative designs for small volume nebulizers have been introduced.

Mechanical Ventilation

Mechanical ventilation refers to the use of a mechanical device to provide ventilatory support for patients. In 1744, Fothergill advocated mouth-to-mouth resuscitation for drowning victims.1,6 During the mid to late 1700s, there was a great deal of interest in resuscitation, and additional procedures for cardiopulmonary resuscitation (CPR) were developed.^1,4,6 Positive pressure ventilation using a bag-mask system or bellows was suggested. However, the observation that a fatal pneumothorax may result caused this technique to be rejected around 1827.^1,4 Interest in negative pressure ventilation developed, and the first negative pressure tank ventilator was described in 1832.⁶ Other negative pressure ventilators began to appear in the mid-1800s; in 1928, the iron lung was developed by Drinker, an industrial hygienist and faculty member at Harvard University.¹ Emerson developed a commercial version of the iron lung that was used extensively during the polio epidemics of the 1930s and 1950s (Figure 1-1).^1,11 The chest cuirass negative pressure ventilator was introduced in the early 1900s, and a negative pressure “wrap” ventilator was introduced in the 1950s.¹² Other early noninvasive techniques to augment ventilation included the rocking bed (1950) and the pneumobelt (1959).¹²

Originally, positive pressure ventilators were developed for use during anesthesia and later were altered for use on hospital wards.¹³ Early positive pressure ventilators included the Drager Pulmotor (1911), the Spiropulsator (1934), the Bennett TV-2P (1948), the Morch Piston Ventilator (1952), and the Bird Mark 7 (1958) (Figure 1-2).^1,13 More sophisticated positive pressure volume ventilators were developed in the 1960s and included the Emerson Postoperative Ventilator, MA-1 (Figure 1-3), Engstrom 300, and Ohio 560.^1,13 A new generation of volume ventilators appeared in the 1970s that included the Servo 900, Bourns Bear I and II, and MA-II. By the 1980s, microprocessor-controlled ventilators began to appear, led by the Bennett 7200 in 1984, and in 1988, the Respironics BiPAP (bilevel positive airway pressure) device was introduced for providing noninvasive positive pressure ventilation in a wide variety of settings.¹ During the 1990s and early 2000s, new ventilators have continued to be developed, including the Hamilton Galileo, Servo-i, Bennett 840, and Drager Evita series (see Chapter 42). Since 1970, more than 50 new ventilators have been introduced with various characteristics for clinical use.^14,15

Early mechanical ventilators provided only controlled ventilation. “Assist-control” as a mode of ventilation appeared with the early Bird and Bennett pressure-limited ventilators in the 1950s, which were often used for intermittent positive pressure breathing (IPPB). Positive end-expiratory pressure (PEEP) was introduced for use in patients with acute respiratory distress syndrome (ARDS) in 1967. The modern form of intermittent mandatory ventilation (IMV) was introduced in 1971, followed by synchronized intermittent mandatory ventilation in 1975 and mandatory minute volume ventilation in 1977.1,4 Pressure support ventilation and pressure control ventilation were introduced in the 1980s, followed by airway pressure release ventilation and inverse ratio ventilation. In the 1990s, volume support ventilation, pressure-regulated volume control, and adaptive support ventilation were introduced. The commercial implementation of proportional assist ventilation and other modes of ventilation occurred in the twenty-first century.

Because traditional short-term mechanical ventilation, regardless of mode, necessitates the use of an endotracheal tube, there is always the potential for a serious infection known as ventilator-associated pneumonia (VAP). VAP is a deadly and very costly consequence of invasive mechanical ventilation that develops when external microorganisms accidentally enter the airway. There has been a concerted effort to try to support inadequate ventilation noninvasively, by using a nasal or full-face mask, to avoid the need for endotracheal intubation. When noninvasive ventilation does not work and endotracheal intubation is necessary, respiratory therapists must be constantly vigilant in their efforts to prevent VAP.

Airway Management

Airway management refers to the use of various techniques and devices to establish or maintain a functional air passageway. Tracheotomies may have been performed to relieve airway obstruction in 1500 bc.⁶ Galen, the Greek anatomist, described a tracheotomy and laryngeal intubation in 160 ad. Vesalius, the anatomist, described a tracheotomy in an animal in 1555.^1,6 In 1667, Hooke described a tracheotomy and use of a bellows for ventilation.⁶ In 1776, tracheal intubation was suggested for resuscitation.⁶ In 1880, MacEwen reported success with oral endotracheal intubation in patients.⁶ O’Dwyer further described the technique for endotracheal tube placement. By 1887, Fell had developed a bellows-endotracheal tube system for mechanical ventilation, and this system was used in 1900 to deliver anesthesia.⁶

In 1913, the laryngoscope was introduced by Jackson. Additional early laryngoscopes were designed by Kirstein, Janeway, and others.1,6 Endotracheal intubation for anesthesia administration was firmly established by World War I. After the war, Magill introduced the use of soft rubber endotracheal tubes, and this made blind nasal intubation possible, as described by Magill in 1930.⁶ In 1938, Haight advocated nasotracheal suctioning for secretion removal, and in 1941, Murphy described the ideal suction catheter, which included side holes known as “Murphy eyes.”⁶ The double-lumen Carlen tube for independent lung ventilation was introduced in 1940, followed by a double-lumen tube developed by Robertshaw in 1962. Damage to the trachea by the tube cuff was reduced with the introduction of low-pressure cuffs in the 1970s.⁶

Cardiopulmonary Diagnostics and Pulmonary Function Testing

Pulmonary function testing refers to a wide range of diagnostic procedures to measure and evaluate lung function. The volume of air that can be inhaled in a single deep breath was first measured in 1679, and the measurement of the lung’s residual volume was first performed in 1800.⁹ In 1846, Hutchinson developed a water seal spirometer, with which he measured the vital capacity of more than 2000 subjects.^9,16 Hutchinson observed the relationship between height and lung volume and that vital capacity decreases with age, obesity, and lung disease. Hering and Breuer described the effects of lung inflation and deflation on breathing—the “Hering-Breuer reflex”—in 1868.⁴ In 1919, Strohl suggested the use of forced vital capacity (FVC), and in 1948, forced expiratory volume in 1 second (FEV₁) was suggested as a measure of obstructive lung disease by Tiffeneau.⁹

Arterial and venous oxygen and carbon dioxide contents were measured in 1837, and methods to measure blood oxygen and carbon dioxide levels were available in the 1920s. These early methods for measuring blood oxygen, carbon dioxide, and pH were slow and cumbersome. In 1967, the combined pH, Clark, and Severinghaus electrodes produced a rapid and practical blood gas analyzer for routine clinical use.1,4 The ear oximeter was introduced in 1974, and the pulse oximeter was introduced in the 1980s. Sleep medicine became well established in the 1980s, and polysomnography became a routine clinical test, often performed by respiratory therapists.

Respiratory Care Week

In November 1982, President Reagan signed a proclamation declaring the third week of each October as National Respiratory Care Week. Since then, Respiratory Care Week has become a yearly event to promote lung awareness and the work of respiratory therapists is all care settings. Respiratory therapists (and students) around the United States use Respiratory Care Week to celebrate their profession and dedication to quality patient care. Many respiratory care departments use the opportunity to conduct special events in their hospitals to help raise awareness of the vital role the respiratory therapist plays as a member of the health care team. Other departments plan community activities to help the public understand the importance of good lung health and the role respiratory therapists play in diagnosing and treating breathing disorders. Respiratory Care Week is also an excellent opportunity for respiratory therapy students to become ambassadors of the profession to the rest of the student body. Some respiratory therapy classes conduct free breathing tests on campus, in shopping malls, or in community centers.

Fellow of the American Association for Respiratory Care (FAARC)

In any given profession, there are always individuals who go above and beyond what is expected of the average practitioner. To recognize respiratory therapists and physician members who have done so in our profession, the AARC established the Fellow of the American Association for Respiratory Care (FAARC) award in 1998. To be considered for FAARC status, nominees must be either a registered respiratory therapist or a licensed physician and have a minimum of 10 consecutive years of membership in the AARC. Of greater importance, nominees for FAARC must show superior achievement in patient care and as a volunteer serving the profession. Individuals selected to receive this prestigious award are so noted by having “FAARC” appear after their name following educational degrees and credentials.

Board of Medical Advisors (BOMA)

Because respiratory therapists can practice only under medical direction, it is essential that the AARC leadership receive formal input from physicians on all matters and questions pertaining to patient care. The Board of Medical Advisors (BOMA) is the group of physicians who provide this valuable input. The BOMA comprises approximately 18 physicians who are appointed by their respective professional medical associations (e.g., American College of Chest Physicians, American Thoracic Society, Society for Critical Care Medicine) to serve this cause voluntarily. The BOMA meets annually, but the chairperson of the BOMA attends all meetings of the AARC Board of Directors. Individual members of the BOMA are assigned by the AARC president to serve as a medical liaison to each of the 10 Specialty Sections of the AARC. Effective medical direction at the hospital level is indispensable for the practice of safe, high-quality respiratory care.

American Respiratory Care Foundation (ARCF)

Established in 1970 by the AARC, the American Respiratory Care Foundation (ARCF) is a not-for-profit charitable foundation that helps promote and further the mission of the AARC. Commonly known as the Foundation, the ARCF collects and manages contributions from individuals, corporations, and other foundations to recognize individual achievements of excellence in clinical practice, chronic disease management, public respiratory health, scientific research, and literary excellence. The ARCF also provides research grants to establish the scientific basis of respiratory care further. Lastly, the ARCF oversees and distributes numerous scholarships for respiratory therapy students who are student members of the AARC. The ARCF awards and scholarships are presented at the awards ceremony held in conjunction with the annual International Respiratory Congress of the AARC. Respiratory therapy students who are interested in applying for an ARCF scholarship should visit the ARCF website (see www.arcfoundation.org) to learn more about this great opportunity.

International Council for Respiratory Care (ICRC)

The International Council for Respiratory care (ICRC) is an AARC-sponsored organization dedicated to the globalization of quality respiratory care. As mentioned previously, having formally trained professionals who were not physicians or nurses and who worked in a dedicated department assume full responsibility for providing respiratory care was a uniquely North American phenomenon, limited only to the United States and Canada. However, during the 1970s and 1980s, when many foreign physicians came to the United States to study, they became aware of what a respiratory therapist was and the important role the respiratory therapist played in hospitals nationwide. When these physicians returned to their native countries, they wished to have their own specialized team able to provide the same level of quality respiratory care. However, because the health care delivery system is structured differently in each country, the specially trained teams were most often nurses, physicians, or physical therapists, not respiratory therapists.

Formed in 1991, the ICRC (in close collaboration with the International Committee of the AARC) began to offer fellowships to interested foreign clinicians that provide the opportunity to visit the United States for 2 weeks before the annual International Respiratory Congress to observe how practice respiratory care is practiced. The idea is to allow these international fellows to observe how the various components of respiratory care are practiced in several cities. The international fellows can take back to their home countries ideas and practices that can be integrated into their unique health care delivery systems. The program has been so successful that many countries (e.g., Mexico, Costa Rica, Taiwan) are starting to establish respiratory therapy training programs similar to the American model. As of 2010, 135 international fellows from 54 countries have participated in this program.

National Board for Respiratory Care (NBRC)

The credentialing body for registered respiratory therapists began in 1960 as the American Registry of Inhalation Therapists (to test and credential registered therapists), and a certification board was established in 1968 to certify technicians.1,4 These two groups merged in 1974 as the National Board for Respiratory Therapy, which became the National Board for Respiratory Care (NBRC) in 1983.^1,4 Also in 1983, the National Board for Cardiopulmonary Technologists joined the NBRC, and the credentialing examinations for pulmonary function technology were brought in under the respiratory care umbrella.^1,4 Since 1968, there have been two levels of clinical practice credentialing examinations in the United States: the certified technician and the registered therapist (see www.NBRC.org).

In 1998, the NBRC renamed the lower level certified respiratory therapist (CRT, or entry-level respiratory therapist); the advanced level remained registered respiratory therapist (RRT, or advanced-level respiratory therapist).¹⁹ The NBRC began offering specialty examinations for pulmonary function technology in 1984 and neonatal/pediatrics in 1991. The NBRC is considering new specialty credentialing examinations in the areas of polysomnography and critical care.

Committee on Accreditation for Respiratory Care (CoARC)

In 1956, the first guidelines for respiratory care educational programs were published, followed by the formation of the Board of Schools to accredit programs in 1963.¹ The Board of Schools was replaced by the Joint Review Committee for Inhalation Therapy Education (JRCITE) in 1970, led by its first chairman, Helmholtz.^1,4 The JRCITE became the Joint Review Committee for Respiratory Therapy Education (JRCRTE) in 1977 and then the Committee on Accreditation for Respiratory Care (CoARC) in 1996 (see www.COARC.com).⁴ Today, respiratory care educational programs in the United States are accredited by the CoARC in collaboration with the Association of Specialized and Professional Accreditors.^20–22

2015 and Beyond

In 2005, recognizing that many national politicians were beginning to call for an overhaul of the U.S. health care delivery system, the AARC Board of Directors began to think strategically, which led to the formation in 2007 of a special task force called “2015 and Beyond.” The task force was charged with the task of envisioning potential new roles and responsibilities of respiratory therapists by 2015 and beyond. The leadership of the task force decided to convene three strategic conferences to answer the following five key questions about the profession:

The initial 2015 and Beyond conference was held in the spring of 2008, and a consensus was reached that there were likely to be:

In the words of one conference organizer, “the take home message was that indeed the scope and depth of respiratory care practice will increase by 2015.”³⁹ The second conference was held in the spring of 2009 and built on the findings of the 2008 conference by identifying the competencies needed by graduate respiratory therapists and the educational content and curriculum that would be needed to practice in 2015 and beyond. Conference participants agreed that there would be seven major competencies (Box 1-5) that future respiratory therapists would need to practice effectively by 2015.^40,41 The third conference was held in the summer of 2010 to determine how the educational programs for entry-level respiratory therapists would have to be structured to accomplish the seven major competencies identified during the 2009 conference. The recommendations of the third conference were published in 2011.⁴²

Although the respiratory care profession is undergoing substantial change, there will be a continuing demand for respiratory care services well into the future because of advances in treatment and technology, increases in the general population, and increases in the elderly population (the baby boomers). A growing population will result in increases in asthma, COPD, and other chronic respiratory diseases. There will also be a continuing demand for controlling costs and ensuring that care provided is evidence-based, safe, and effective. Respiratory care will need to be provided using carefully designed protocols to ensure that patients get the appropriate care at the right time and that unnecessary care is reduced or eliminated. Aggressive steps to prevent disease and control the cost of chronic respiratory disease will be essential. Effective smoking cessation and tobacco education programs and aggressive disease management and pulmonary rehabilitation for patients with moderate to severe asthma, COPD, and other chronic respiratory disease will continue to be needed.

As exemplified by the 2015 and Beyond project, the knowledge, skills, and attributes needed by respiratory therapists will continue to expand, and it will become increasingly difficult to prepare respiratory therapists for expanded practice within the credit hour limitations of many existing programs. To alleviate this situation, associate degree programs may develop articulation agreements with 4-year colleges and universities to allow their graduates to complete the bachelor degree in respiratory care without leaving their home campus; distance education technology will play an important role and allow this to occur at minimal cost.

Bachelor degree programs often seek to provide students with a foundation for leadership in the profession in the areas of management, supervision, research, education, or clinical specialty areas. To meet the leadership needs of the profession, some baccalaureate programs have already implemented postbaccalaureate certificates or master degree programs. Clinical areas in which more graduate education programs could be beneficial include critical care, cardiopulmonary diagnostics, clinical research, sleep medicine, rehabilitation, and preparation as a pulmonary physician assistant. There will also be an increasing demand for respiratory therapists with master and doctoral degrees to serve as university faculty, educators, and researchers.