Multidisciplinary multiattribute concept analyses related to the aerohemodynamics conceptual model

Teaching and Learning in Nursing (2009) 4, 98–103

www.jtln.org

Multidisciplinary multiattribute concept analyses related to the aerohemodynamics conceptual model Darlene Sredl PhD, RN⁎ College of Nursing, University of Missouri at St. Louis, St. Louis, MO KEYWORDS: Flight nursing; Aerohemodynamics theory; Concept Analyses

Abstract Topic: These concept analyses explore the threshold limit values of the major conceptual composites comprising the aerohemodynamics theory, namely, acceleration, barotrauma, gaseous toxicities, thermostability, and radiation hazards. Purpose: This theory forms the basis for nursing practice in the flight environment. The sources of information are reference texts, National Aeronautics Space Administration, and Air Force research. Conclusion: Concept analysis of these variables will enable further research into the flight environment's effects upon humans. © 2009 National Organization for Associate Degree Nursing. Published by Elsevier Inc. All rights reserved.

1. Introduction These concept analyses explore the threshold limit values of the major conceptual composites of the aerohemodynamics theory. This theory is the conceptual model that forms the basis for nursing practice in the flight environment. Science is an organized body of knowledge that establishes general laws in a specific discipline governing practice. Nursing requires science to provide an organized body of knowledge focusing on physiological and environment changes at altitude to guide nursing practice (Sredl, 1983). The metaparadigm of nursing encompasses four paradigms: person, nursing, health, and environment. The aviation environment is concerned with all four paradigms: nursing a person's health in relation to a foreign environment (Sredl, 1983). These concept analyses follow the prescriptive advice of Walker and Avant's (2005) use of the Wilsonian method in developing the individual concepts under analysis. As Walker ⁎ Corresponding author. Tel.: +1 314 516 7060 (Office), +1 636 391 9277 (Home). E-mail addresses: [email protected], [email protected]

and Avant propose, concepts are mental constructions that we formulate in an attempt to provide order to our environment. The specific environment under discussion in this article is the airborne environment of conveyances that provide humans with safe travel. Only by quantifying the ideological tenets inherent within each concept that makes up the aerohemodynamics theory can we apply research methodology to gainfully expand our knowledge base in this important area.

2. Sections Each of the main concepts that are explored in this article will be categorized by definition; purpose and uses; and a table that identifies the critical attributes of each concept, along with antecedents, consequences, empirical referents, and instruments with which each of the critical attributes may be empirically tested. At the center of the representational model of a triangle is the person. It is nursing the health of the person in the flight environment that we are attempting to explain by way of presenting the following concepts.

1557-3087/$ – see front matter © 2009 National Organization for Associate Degree Nursing. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.teln.2008.05.002

Multidisciplinary multiattribute concept analyses related to the aerohemodynamics conceptual model

3.3.2. Contrary case Horace, a 15-year-old adolescent lays contentedly on the couch while his fingers do the walking, talking, and pressing buttons on his PlayStation.

3. Acceleration 3.1. Definition The definition of acceleration is that it is a form of motion that causes an increase or change in velocity, including changes in both rate and direction of that velocity (Sredl, 1983).

4. Barotrauma 4.1. Definition

3.2. Uses Acceleration may cause venous pooling that can lead to orthostatically induced syncope in those exposed to rapid accelerative changes, may also lead to blackout/redout, and can cause sufficient cranial hypertension as to lead to a stroke in some cases (Self et al., 1996; Sredl, 1983). Acceleration changes can also lead to motion sickness (Bonato, Bubka, & Story, 2005; Table 1).

3.3. Constructed cases The following are constructed cases as suggested by Walker and Avant (2005). The first constructed case is the model case that contains all of the critical attributes identified as comprising acceleration. 3.3.1. Model case Fasten your seat belts! When superathlete and seven-time Tour de France winner Lance Armstrong courted country western singer Sheryl Crow, the public was amazed by the “speed” and “intensity” with which the relationship developed. At first, it was not clear if the two celebrities were aligned in a “movement positioning” for an upward climb (“positive g-force”) in publicity. The “velocity” of the public's perception of the relationship took a rapid “rate” plunge (“down”), however, after only a short “duration,” leading to a dizzying tumultuous dive that effectively “grayed out” then “blacked out” the relationship. With red (“redout”) eyes, Sheryl announced the end of the relationship.

Table 1

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Barotrauma is a collective term describing physiological effect of dysbarisms occurring within the body as a direct result of changes in barometric pressure or as pressure on an object caused by atmospheric layers above (Mortazavi, Eisenberg, Langleben, Ernst, & Schiff, 2003; Sredl, 1983).

4.2. Uses Barotrauma also leads to an expansion of gases within the body in accordance with Boyle's and Dalton's laws (Mortazavi et al., 2003; Sredl, 1983). This expansion is called “vacuolization,” and it can also cause a form of barometric pressure injury (Sredl, 1983). Discomfort caused by intestinal gas expansion (a 25% volume expansion at an altitude of 8,000 ft) can put postsurgical patients at risk of suture rupture and bleeding (Aerospace Medical Association Medical Guidelines Task Force, 2003). The following are constructed cases as suggested by Walker and Avant (2005). The first constructed case is the model case that contains all of the critical attributes identified as comprising barotrauma (Table 2).

4.3. Constructed cases 4.3.1. Model case The diver descended another 30 ft into the depths of the ocean. Nearing 60 ft below the surface, the water pressure pressed against his skin, constricting his tissues. The diver knew from his training that like the difference in a falling

Concept analysis—acceleration

Antecedent

Critical attribute

Consequence

Empirical referent

Instrument

1. Horizontal 2. Horizontal 3. Homeostasis 4. Stasis 5. Homeostasis 6. Homeostasis 7. No movement/inertia 8. Stasis 9. Stasis 10. g-force 11. Stasis 12. Still 13. No seat belt 14. Stasis

Up Down Blackout Speed Grayout Redout Velocity Intensity Duration Increasing g-force Movement Positioning Seat belt on Rate

Level of altitude Land Unconscious Position change Dizziness Eyelid engorgement Movement Force Length of time passage N1 g-force Change position Position change Fastened in place Position change Over time

Eyes toward sky Eyes toward earth Unconscious person Rapid movement from place to Verbalizations of dizziness Inability to open eyes Rapid movement from place to Fervor Time on clock Skin pressed against bone Discernable position Change Seated or laying down Rapid movement from place to Rapid movement from place to

Level, stabilizer, artificial horizon Level, stabilizer, artificial horizon Level of consciousness Velocemeter Descriptor statement Descriptor statement Moving vector Inactivity Clock Rapid deceleration Velocemeter Observation of movement Presence of seat belt Velocemeter

place

place

place place

100 Table 2

D. Sredl Concept analysis—barotrauma

Antecedent

Critical attribute

Consequence

Empirical referent

Instrument

1. 2. 3. 4.

Pressure Trauma Bleeding Vacuolization

Positive pressure Life-threatening injury Exsanguinization Bubbles/Bubble expansion

5. Differentiated tissue 6. Perfused tissue 7. Air trapped in tooth

Differentiated tissue Necrosis Barodontalgia

Necrosis Death Tooth ache

Touching force applied to skin Skin laceration Observation of blood See large bubbles in carbonized liquid Blackening Blackening/Rigor mortis Complaints of tooth pain

8. Air trapped in sinus cavities 9. Humidity 10. Sunshine

Barosinusitis

Pain

Complaints of pain

Falling barometer Rising barometer

Storm Fair weather

Rain/Snow Sunny day

Skin blanching Observation Visual presence of blood See large bubbles in carbonized liquid Blackening Blackening Verbalization of pain on a scale of 0–10 Verbalization of pain on a scale of 0–10 Barometer Barometer

Negative pressure No injury Intact blood vessels Liquid

barometer versus a rising barometer, the problems he might experience were more likely to occur if he had to ascend quickly. If that were to happen, the diver knew that the gases trapped in his bloodstream would form bubbles and vacuolize or expand, possibly to the point of causing trauma and even tissue necrosis. He knew also that he would experience extreme pain caused by gases trapped in confined spaces such as in tooth cavities (barodontalgia) and sinus cavities (barosinusitis). Ascending in the situation decidedly worsened as he began bleeding from his nose. 4.3.2. Contrary case The astronauts floated weightlessly around the cabin of the space shuttle as they performed their many researchrelated duties.

involved oxygen-providing equipment failure (Cable, 2003). A study by Thake, Mian, Garnham, and Mian (2004) on circulating leukocyte counts subjected to a hypoxic situation found that neutrophil phagocytic function is suppressed by hypoxia, a situation of much interest to nursing researchers. Cognition and performance of mental tasks are also affected by hypoxia (Bolgg & Gennser, 2006; Pavlicek et al., 2005; Tables 3 and 4).

5.3. Constructed cases The following are constructed cases as suggested by Walker and Avant (2005). The first constructed case is the model case that contains all of the critical attributes identified as comprising gaseous toxicities.

5.2. Uses

5.3.1. Model case Ted Hughes, Great Britain's poet laureate, lost his wife in a tragic suicide in the 1990s. Whatever emotional climax may have led to the death of Sylvia Plath (author of “The Bell Jar”), the reason for the decision to take her own life is unclear. What is clear, however, is the devastating toxicity of the carbon monoxide gas vapor that she breathed in. Unlike ozone that has three oxygen atoms within the molecule, carbon monoxide has only one oxygen atom part. When the ambient pressure of the airborne gas is inhaled, the respiration–ventilation pattern of the aerosolized gas in a closed ventilation system is lethal. Acting like an airborne infection of sorts and the more intensified the moisture humidity level is, the carbon monoxide forms an irreversible bond with the hemoglobin in the blood, rendering it ineffective for oxygen transport. Even exhaling the toxic gas and receiving pressurized oxygen therapy with a rebreather mask will not help. Death ensues rapidly from hypoxia.

A study was undertaken by the Directorate of Safety of the Australian Defence Force consisting of an analysis of all incidents listing hypoxia as a factor in the occurrence of the incident between 1990 and 2001. Most symptoms were reported as occurring between 10,000 and 19,000 ft and

5.3.2. Contrary case The patient lay with his blackened foot supported on pillows. The anaerobic gangrenous bacteria were slowly but surely progressing up his leg. Although it had been explained to this patient that death was the only outcome

5. Gaseous toxicities 5.1. Definition The atmosphere, considered as a whole, may be defined as a gaseous envelope that surrounds the earth (Sredl, 1983). Gaseous toxicities include those gaseous products that if present by their nature or if not present (such as oxygen) cause cellular death (Sredl, 1983). Passengers in flight at altitudes ranging from 5,000 to 8,000 ft breathe the equivalent of 17.2%–15.1% of the oxygen that would be available to them at sea level (Buchdahl, Babiker, Bush, & Cramer, 2001). Some of the major gases explored in this article because of their relevance or prevalence are oxygen, carbon monoxide, and ozone.

Multidisciplinary multiattribute concept analyses related to the aerohemodynamics conceptual model Table 3

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Concept analysis—gaseous toxicities

Antecedent

Critical attribute

Consequence

Empirical referent

Instrument

1. Liquid 2. Normal level of a gas 3. Lack of oxygen (O2) 4. Combustion 5. O2

Gas Toxicity

Molecular expansion Death

Presence noted by gas detector Absence of vital signs

O2 Carbon monoxide (CO) Ozone (O3)

Hypoxia Irreversible reaction Symptoms mimic myocardial infarction Suffuse with O2

Decreased PO2 Cherry red lips Coughing, anxiety, chest pain

Gas detector Measurement via auscultation, sphygmomanometer O2 saturation meter CO meter O3 detector

6. No diaphragm expansion 7. No diaphragm expansion 8. No diaphragm expansion 9. Ambient pressure 10. Open ventilation system 11. Breathable 12. 13. 14. 15. 16. 17. 18.

Breath Air Pathogen Water Water Water Gas

19. Ability to breathe 20. Inhale 21. Atom 22. Electrons, protons, neutrons 23. O2 present 24. Life

Observation of diaphragm rising and falling Respiration Suffuse with O2 Observation of diaphragm rising and falling Observation of diaphragm Ventilation Suffuse with O2 rising and falling Pressurization Containment Closed system able to sustain life at 8,000 ft Closed ventilation system Rebreath Gaseous containment in closed system Ambient pressure Ability to live Ability to move and breathe at will Rebreather mask O2 depletion Breath same air Airborne Droplet spread Above ground Airborne infection Inhaled respiratory pathogen Respiratory illness symptoms Moisture Rain Relative humidity score Humidity % of water in air Relative humidity score Vapor Aerosolized water Aerosolized droplets of water in air Aerosol Pressurized release of Gaseous escape gas molecules Inhale Exhale To breathe in Exhale Tissue O2ation To breathe out Molecule Mass Microscope Atom parts Build mass/Split mass Microscope Breathe

Hypoxia

Lack of O2

Inability to breathe

Death

Decay

Absence of vital signs

of not treating this disease, he steadfastly chose not to have an amputation.

6. Thermostability 6.1. Definition Thermostability is an environment in which the temperature remains constant (Sredl, 1983; Table 5).

Observation of diaphragm rising and falling Observation of diaphragm rising and falling Observation of diaphragm rising and falling Closed system Closed system Closed system Visualization of mask Measurement of height Detection of viral or microbials Relative humidity score Relative humidity score Relative humidity score Gas detector Observation Observation Microscope Microscope Increased respiratory rate; use of accessory muscles; automatism Absence of vital signs

and the ambient temperature of the surrounding environment was still hot. One could even see steam vaporization billowing upward from the boiling volcanic combustion fiery thermals. As the ship neared Alaska, however, the frozen glaciers and icebergs in the already-cold sea water made navigation treacherous. At one point, the passengers heard a loud, roaring noise, and many on deck looked landward in time to see an avalanche of snow and ice cascading down a nearby mountainside. Melanie smiled when she noticed that even the tear making its slow way down her cheek froze like her own personal icicle.

6.2. Uses A thermostabile environment at altitude cannot be overemphasized because thermal excess may cause apneic episodes, high metabolic rate, and burns when applied to localized sites (Sredl, 1983).

6.3. Constructed cases 6.3.1. Model case The stress and uncertainty of an Alaskan cruise were beginning to take its toll on Melanie's stability and equilibrium. The cruise departed from the Hawaiian Islands in the spring,

Table 4

Dry atmospheric composition

Gas

%

Nitrogen Oxygen Argon Carbon dioxide Hydrogen Neon Helium

78.08 20.93 0.94 0.03 0.01 0.0012 0.0004

Note. Reprinted with permission from Sredl (1983).

102 Table 5

D. Sredl Concept analysis—thermostability

Antecedent

Critical attribute

Consequence

Empirical referent

Heating/Cooling element Space No equilibrium Ambient equilibrium No tension

Temperature Environment Equilibrium Heat Stress

Heat/Cool Surroundings Homeostasis Boiling NTension

Thermometer Living space Calmness Steam NAnxiety

Instability Thermal instability Ambient equilibrium Cold Ambience Liquid Solid mass Cold water Cold water Cold water High humidity High humidity Glacial ice intact No combustion Neutral temperature Neutral temperature

Thermometer Area No discernible change Thermometer NHeart rate, respiratory rate, and blood pressure Stability Equilibrium Homeostasis No discernible change Ambient Equilibrium Homeostasis No discernible change Boil Steam Steam Thermometer Freeze Ice Ice Thermometer Thermal Temperature measurement Thermometer Thermometer Steam Condensation Water molecules visible in air Thermometer Vaporization Spatial molecular escape Water molecules visible in air Water molecules visible in air Ice Water molecular expansion Ice Visualization of expanded water Icicles Gravity-directed frozen water Tubular hanging ice Visualization of expanded water Glacier Water frozen into large block of ice Massive ice Visualization of expanded water Avalanche Destructive snow path Snow flow Visualization of large mass of snow flow Snow Frozen water crystals Floating ice crystals Visualization of ice Iceberg Ice floating in water Ice floes in water Visualization of expanded water Fire Mass destroyed Flame Flames visible Vaporization Water droplets suspended in air Water molecules visible in air Water molecules visible in air Combustion Fire Fire Flames visible

6.3.2. Contrary case In the child's dream, he floated effortlessly, feeling neither heat nor cold, hunger nor satiety, and thirsty nor parched.

7. Radiation exposure 7.1. Definition Radiation or the emission of electromagnetic waves emitted from a specific broadcast source is an energy source that travels under various guises (Sredl, 1983).

Table 6

Instrument

7.2. Uses Radiation can be measured in terms of roentgens, which is 1 measurable unit of radiation (Sredl, 1983). A roentgen equivalent man is the quantity of radiation of particles which when absorbed by living tissue produce the same effect as the absorption of 1 rad of x-rays or gamma rays (Sredl, 1983). Use of the term rad has grown popular, and it also is a direct measure of energy. One rad is equivalent to the absorption of enough radiation in any form to liberate 100 ergs of energy per gram of absorbing material. In most cases, the rad is approximately equal to the roentgen (Sredl, 1983; Table 6).

Concept analysis—radiation exposure

Antecedent

Critical attribute

Consequence

Empirical referent

Instrument

1. No radiation 2. No exposure 3. No radiation 4. Sunlight 5. Quiet 6. Sound 7. Flight on ground 8. Silence 9. Equipment off 10. No chemical 11. Darkness 12. No equipment 13. Silence 14. No radiation 15. Low humidity

Radiation dose Exposure Rad UV ray Sound Ultrasound Transponder Communication Frequency Sunblock Ray Radio equipment ELT Microwave Clouds

Absorption Absorption Unit of radiation Heat Radiation Heat Continuous electronic signal emission Comprehension Communication channel Limited skin exposure to UV ray Light Receive/Send messages Signal Heat Filter

Sunlight Sunlight Microwave Light Radio Ultrasound machine Transponder Spoken word Tune to sound UV block lotion applied to exposed skin Vision Music/News Transmission device Cook Shade

Source of radiation Source of radiation Source of radiation Source of radiation Audible sound waves Ultrasound machine Transponder Audible sound waves Sound Chemical compound Light Audible sound waves ELT equipment Heat Moisture in atmosphere

Note. UV = ultraviolet; ELT = emergency locator transmitter.

Multidisciplinary multiattribute concept analyses related to the aerohemodynamics conceptual model

7.3. Constructed cases The following are constructed cases as suggested by Walker and Avant (2005). The first constructed case is the model case that contains all of the critical attributes identified as comprising radiation exposure. 7.3.1. Model case Dr. Harvey was a well-respected physician employed in the radiation therapeutics department of a large Midwestern hospital. She had a “depth” of experience with many different types of radiation dosing including x-rays, gamma rays, ultraviolet, ultrasound, and microwave emissions and even rad exposure to such technical instruments as airline sound communication, radio transponder, and emergency locator transmission. Dr. Harvey was called upon to testify as an expert witness during many court cases involving frequency of exposure to skin cancer caused by the sun's rays—even through clouds and sunblock lotion. 7.3.2. Contrary case The elderly couple from the Midwest decided to have a vacation in the Bahamas. Because of the negative publicity about skin damage caused by the sun, the couple spent the duration of their vacation playing cards in their darkened hotel room.

8. Conclusion The higher priority, independent variable of acceleration stress, is composed of the various positions of roll, pitch, and yaw, immediately acting upon the body, whereas the lower priority dependent variables of barometric pressure, thermostability, gaseous toxicities, and radiation exposure tend to be of slightly longer duration in effecting a change upon the body. It is hoped that the preceding explanation of concepts

103

comprising the aerohemodynamics theory will be of benefit to nurse researchers in future studies of the effects of the airborne environment on alterations in human physiology.

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