Journal of Gerontological Nursing

Effects of Air & Water Mattresses on Thermoregulation

Barbara J Wirtz, RN, MSN

Abstract

Many hospitalized geriatric clients face the potential and actual situational hazardous event of decubiti formation. Decubiti formation can be attributed to a variety of factors including age, poor nutritional status, reduced mobility, and incontinence. Pressure as an etiologic factor in the development of ischemia over bony prominences has been documented in classic studies by Kosiak1,2 and more recently by Agris and Spira;3 Narset, Orgel, and Smith;4 and Hagen.5 There has been continuous research in methods of preventing decubiti formation and in the development of preventive devices. These are intended to reduce the pressure on bony prominences either by distributing the load more equally or by rhythmic elimination of the pressure on any area. Although the health professional utilizes these devices for prevention and cure, patient comfort must also be a consideration.

Hagen5 states that about 30% of the nursing home population will develop a pressure sore. In an effort to decrease and eventually eliminate the problem, numerous preventive devices are used in geriatric settings. Two of the methods used for prevention and treatment of decubiti are the alternating air mattress and the water mattress. Alternating air mattresses are available in many designs, but all are based on the same principle. They are made of vinyl and require an electrical pump to generate the flow of air. Air flow is alternated among the cylindrical tubes of the mattress, thus avoiding constant pressure on any segment of the client's skin surface.

Water mattresses are similar to the vinyl mattresses used for camping except that they are filled with water rather than air. These mattresses utilize the principles of floatation and displacement as a method of reducing and distributing pressure on the client's skin surface. Water mattresses are initially filled with warm tap water, but eventually assume room temperature since they do not have a heating element. Upon investigation, it was noted that the skin of these clients in contact with the water mattress was cold to the touch. Some clients complained of discomfort due to the cold.

The air and water mattress both have been evaluated and criticized in the literature. However, an area which has not been addressed is the effect of the temperature of the water in an unheated water mattress on the client.

Conceptual Framework

The crisis model provided the conceptual framework for this study, ie, where each individual faces a series of situational and developmental hazardous events in his or her lifetime. Situational hazardous events are sudden and unexpected happenings that threaten a person's biological, physiological, and/or social integrity, while developmental hazardous events occur as part of the normal process of maturational development.6 To the elderly client who is debilitated due to illness, immobility, or malnutrition, the formation of decubiti is a situational hazardous event.

Table

It is essential that the health professional not only minimize hazardous events, but also assist in enhancing the quality of life for the elderly client. This may be achieved by choosing an effective device that prevents further skin breakdown, does not cause any discomfort to the client, and maximizes the client's potential to achieve a higher level of wellness.

Several devices have been used in decubiti prevention. All have as their objective the reduction of pressure. Tlie devices are of particular interest in this study. The first, an air mattress, achieves its effect by alternately inflating and deflating adjacent cylindrical tubes by use of an air pump which requires the use of electricity. The second, a water mattress, achieves its effect by distributing the client's weight over the greatest possible surface area.

Both have been shown to be effective in decubiti prevention.…

Many hospitalized geriatric clients face the potential and actual situational hazardous event of decubiti formation. Decubiti formation can be attributed to a variety of factors including age, poor nutritional status, reduced mobility, and incontinence. Pressure as an etiologic factor in the development of ischemia over bony prominences has been documented in classic studies by Kosiak1,2 and more recently by Agris and Spira;3 Narset, Orgel, and Smith;4 and Hagen.5 There has been continuous research in methods of preventing decubiti formation and in the development of preventive devices. These are intended to reduce the pressure on bony prominences either by distributing the load more equally or by rhythmic elimination of the pressure on any area. Although the health professional utilizes these devices for prevention and cure, patient comfort must also be a consideration.

Hagen5 states that about 30% of the nursing home population will develop a pressure sore. In an effort to decrease and eventually eliminate the problem, numerous preventive devices are used in geriatric settings. Two of the methods used for prevention and treatment of decubiti are the alternating air mattress and the water mattress. Alternating air mattresses are available in many designs, but all are based on the same principle. They are made of vinyl and require an electrical pump to generate the flow of air. Air flow is alternated among the cylindrical tubes of the mattress, thus avoiding constant pressure on any segment of the client's skin surface.

Water mattresses are similar to the vinyl mattresses used for camping except that they are filled with water rather than air. These mattresses utilize the principles of floatation and displacement as a method of reducing and distributing pressure on the client's skin surface. Water mattresses are initially filled with warm tap water, but eventually assume room temperature since they do not have a heating element. Upon investigation, it was noted that the skin of these clients in contact with the water mattress was cold to the touch. Some clients complained of discomfort due to the cold.

The air and water mattress both have been evaluated and criticized in the literature. However, an area which has not been addressed is the effect of the temperature of the water in an unheated water mattress on the client.

Conceptual Framework

The crisis model provided the conceptual framework for this study, ie, where each individual faces a series of situational and developmental hazardous events in his or her lifetime. Situational hazardous events are sudden and unexpected happenings that threaten a person's biological, physiological, and/or social integrity, while developmental hazardous events occur as part of the normal process of maturational development.6 To the elderly client who is debilitated due to illness, immobility, or malnutrition, the formation of decubiti is a situational hazardous event.

Table

FIGUREMEAN DEMOGRAPHIC DATA OF CLIENTS ACCORDING TO TYPE OF MATTRESS

FIGURE

MEAN DEMOGRAPHIC DATA OF CLIENTS ACCORDING TO TYPE OF MATTRESS

It is essential that the health professional not only minimize hazardous events, but also assist in enhancing the quality of life for the elderly client. This may be achieved by choosing an effective device that prevents further skin breakdown, does not cause any discomfort to the client, and maximizes the client's potential to achieve a higher level of wellness.

Several devices have been used in decubiti prevention. All have as their objective the reduction of pressure. Tlie devices are of particular interest in this study. The first, an air mattress, achieves its effect by alternately inflating and deflating adjacent cylindrical tubes by use of an air pump which requires the use of electricity. The second, a water mattress, achieves its effect by distributing the client's weight over the greatest possible surface area.

Both have been shown to be effective in decubiti prevention. However, one problem of concern in using die water mattress may be its effect on the thermoregulation of elderly clients. The water in an unheated water mattress may severely affect the client's surface and central body temperature.

Instrumental in choosing an appropriate preventive device is the understanding of some basic laws of physics. When a thermal grathent exists, heat will tend to move from the high temperature to the low temperature area.7 Conduction, as defined by Ganong,8 is heat exchange between objects at different temperatures that are in contact with one another. More specifically, it is the transfer of heat by the direct interaction of molecules in a hot area with molecules in a cooler area. Microscopically, this interaction is in the form of collisions between molecules, with the more rapidly moving molecules in the high temperature area giving internal energy to molecules in the colder area.

The efficiency of heat conduction depends upon the number of collisions and the amount of energy transferred during each collision. Since conduction occurs from the surface of one object to the surface of another, the temperature of the skin determines to a large extent the degree to which body heat is lost or gained. The amount of heat reaching the skin from the deep tissues can be varied by changing the blood flow to the skin. When the cutaneous vessels are dilated, warm blood wells up into the skin, whereas in the maximally vasoconstricted state, heat is held centrally in the body.

Thermoregulatory adjustments involve local responses and more general reflex responses. When cutaneous blood vessels are cooled, they become more sensitive to catecholamines and the arterioles and venules constrict.

This local effect of cold directs blood away from the skin and into the venae comitantes, the deep veins that run alongside the arteries. Heat is then transferred from the arterial to the venous blood and carried back into the body without reaching the skin. This is known as countercurrent exchange.8 High rates of convection within a thermal system must tend to reduce temperature grathents within it and result in approximation of thermal homogenity.9

Temperature receptors are widely distributed in the skin and connective tissue. The receptors for cold are the endbulbs of Krause which lie near the surface of the skin. The receptors for heat are the corpuscles of Raffine which lie deep in the skin. Because the sense organs are located subepithelially, it is the temperature of subcutaneous tissue that determines the response.8 The sensory area for temperature is in the parietal lobe of the cerebral cortex just posterior to the central fissure.7 The hypothalmus is where the body temperature is regulated.

In the body, heat is produced by muscular exercise, assimilation of food, and alt the vital processes that contribute to the basal metabolic rate. The balance between heat production and heat loss determines the body temperature. Because the speed of chemical reactions varies with the temperature, and because the enzyme systems of the body have narrow temperature ranges in which their function is optimal, normal body function depends upon a relatively constant body temperature.8

There is widespread clinical impression that elderly people are especially susceptible to accidental hypothermia.9 The term "accidental hypothermia" emphasizes the cause of the majority of cases in the elderly in which environmental or endogenous factors play a part either singularly or together. It is denned as a core body temperature of less than 35°C (95°F).11

Risk factors that predispose the elderly client to accidental hypothermia are: a defect in thermoregulation caused by the age-related decline in the autonomie nervous system, malnutrition, immobilization, obtundation," and illnesses such as Addison's disease, cardiovascular disease, hypoglycemia, and myxedema. Contact with cold surfaces causes increased conductive loss.

Given these basic theories from physics and their relationship to the science of nursing, it seems essential to apply them in a practical sense to decubiti prevention.

Review of Literature

The water mattress has been designed to distribute a client's weight over the greatest possible surface area, thus reducing pressure to a minimum.11 Many articles have been written about the water mattress and/or water bed, discussing the effectiveness of eliminating pressure and the importance of preventive care.

Pfaudler13 states the water temperature most comfortable for the client is between 80° to 85°F, but that there were no disastrous effects when the water was inadvertently too hot or too cold. If sweating was noted, the temperature was lowered since diaphoresis can contribute to maceration.

The temperature is maintained simply by removing about 8 gallons of water daily and replacing it with hot water until the desired temperature is reached. Pfaudler also explains that the temperature drops about 5° in 24 hours.

Horsley14 states that the water temperature needs to be finely controlled. Water too hot, 85°F and above, was found to produce maceration. Dewis, Caplan, and Pache15 state that problems with temperature were not encountered in the treatment decubitus ulcers by use on a water mattress.

Literature supplied by Lotus on one of its water mattresses in the section on installation states:

"The mattress initially is filled with warm water 85° to 90°F. After filling, the water soon reaches room temperature, and there is a natural concern for the patient lying on cool water. This concern loses ground when it is understood that the body warms only a thin layer of water directly in touch with the skin - not all the water. The warm water remains on top (close to body temperature), unless the patient vigorously agitates it, which is never the case, because of his condition. However if the patient feels cold, a light blanket should be placed under the sheet above the water mattress for partial heat insulation."16

There is a noticeable lack of information on the effects of water temperature on the client and a possible disregard for the well-being of the client as a whole.

Research Hypothesis

Clients placed on an unheated water mattress will have a lower body surface temperature than those clients who are placed on an alternating air mattress. Likewise, those same clients will have a lower sublingual temperature than those clients who are placed on an alternating air mattress.

Materials and Methods

This methodology is designed to determine whether a relationship exists between the independent variable of the type of mattress and the dependent variable of temperature. To assure that similar clients were studied, the sublingual and body-surface temperature of clients studied were medically stable and had been on preventive mattresses prior to being chosen as participants.

There was no formalized process for institutional review. Informal contact was made with the medical director and permission was granted to proceed with the research. This project did not present any risks to the participants.

Design

This descriptive study uses a prospective approach to collect data in response to the research question.

Setting

This study was conducted at a 336bed chronic care geriatric hospital. Ninety-eight percent of the clients in the facility were males. The average age of the client was 72.2 years and 8% of the clients were over the age of 90.

Sample

Twenty male clients were used as subjects in the study, and a nonprobability approach of quota sampling was utilized. The hospital number of all clients on water mattresses was recorded. Ten clients were randomly selected from the group on the air mattress and ten were selected from the water-mattress group. Sample selection was based on these considerations: the clients were on an air and water mattress and were over the age of 62; the clients were medically stable and remained afebrile during the data-collection period; and if a client developed medical problems or became febrile, he would have been eliminated from the study.

Data Collection

Data collection took place over a 72hour period. Sublingual and body surface temperatures of the clients were measured each morning and night. Each morning the client's body surface and sublingual temperature were recorded, approximately eight to ten hours after they had been on the mattress. At night the temperatures were recorded within two hours of the time the client had been placed on the mattress.

Instrumentation

Sublingual temperatures were recorded using electronic thermometers. The temperature probe was positioned sublingually with the mouth closed until the reading appeared.

Body surface temperatures were recorded using a synergy continuous temperature monitor. This is a batterypowered, solid-state monitor. Disposable, noninvasive skin probes were applied to the client's skin. The range of the synergy monitor is between 89.6° and 107.6°F. The technique was as follows: The skin probe was placed on the client's trunk in an area which had been in contact with the mattress. It was left in place for five minutes.

Limitations

A limitation of this study was the threat to instrumentation. It was not practical to use the same electronic thermometer for the entire 72-hour period. Therefore, there may have been some variation between sublingual temperature measurements.

Results

The data were analyzed using a t-test. A statistically significant difference in the mean temperature between the client on the two types of mattresses was noted. The mean of the group on air mattresses was 94.13 and the mean of the group on water mattresses was 90.39 (t = 6.12, df=18, p = <.005).

On the basis of these data we reject the null hypothesis and accept the first literary hypothesis that clients who are placed on an unheated water mattress will have lower body surface temperatures than those clients placed on an alternating air mattress.

A statistically significant difference was also found between the mean sublingual temperatures of the clients on the different mattresses. The mean of the group on air mattresses was 98.24 and the mean of the group on the water mattresses was 97.1 (t = 3.2, df=18, p = .005). On the basis of this information we reject the null hypothesis and accept the second literary hypothesis that clients who are placed on an unheated water mattress will have lower sublingual temperatures than those clients placed on an alternating air mattress.

Interpretation

The results of this study have shown that clients on unheated water mattresses have lower skin surface temperatures and sublingual temperatures than clients placed on alternating air mattresses. Exposure to cold is an additional unnecessary situational hazardous event. The thermal grathent between the unheated water and the client's skin surface significantly affects the client's thermoregulation. Although not explored in this study, this effect could contribute both to the client's level of comfort and his physiologic well-being.

Implications for Nursing

The primary implications for this study are in clinical practice. Nurses have to be aware of the clinical effects an unheated water mattress may have on an elderly client. If the elderly client is confused, aphasie, or comatose, he may be unable to inform the care giver that he is cold; therefore, providing a comfortable environment is the responsibility of the nurse. To enhance the practice of nursing, the nurse must be alert to the potential of thermoregulatory upset. Nurses at all levels should have input into the type of preventive device a client is placed on.

Nurses in administrative positions must also be alert to this potential problem. For example, when evaluating a decubitus preventive device, the nurse must look at client comfort and client outcome in addition to evaluating a product for cost effectiveness.

Although this study examined the effects of a water mattress on the elderly client, this information also can be used to guide the selection of preventive devices in a rehabilitation setting with younger clients.

Recommendations for Riture Research

Previously published literature has not satisfactorily explored the effects that the temperature of a water mattress has had on the elderly client. Recommendations for future research are: 1. Replicate the study with a larger geriatric sample, including males and females to see if the results hold true; 2. Compare perception of temperature with sublingual and skin surface temperature; and 3. Replicate the study with a younger population in a rehabilitation setting to see if the results hold true.

References

  • 1. Kosiak M: Etiology and pathology of ischemie ulcers. Arch Phys Med Rehabil 1959; 40(2):62-69.
  • 2. Kosiak M: Etiology of decubitis ulcers. Arch Phys Med Rehabil 1961; 42(1):19-28.
  • 3. Agris J & Spira M: Pressure Ulcers: Prevention and treatment. Clin Symp 1980; 31(5):2-32.
  • 4. Marsele TA, Orgel MG & Smith D: Pressure sores. AFP 1983; 28(3)134-139.
  • 5. Hagen BL: Infection control in long term care facilities, in Smith (ed): New York, Wiley & Sons, 1984.
  • 6. Infante MS: Crisis theory: A framework for nursing practice. Virginia, Reston, 1982.
  • 7. Nave C, Nave B: Physics for the Health Sciences, ed 2. Philadelphia, WB Saunders, 1980.
  • 8. Ganong WF Review of Medical Physiology. California: Lange, 1983.
  • 9. Hoffman-Goety L, Keir R: Body temperature responses of aged mice to ambient temperature & humidity stress. J Gerontol 1984:39(5):547-551.
  • 10. Hertzman AB: Some relations between skin temperature and blood flow. Journal of Physical Medicine and Rehabilitation 1953; 32(8):233-249.
  • 11. Rango N: Old and cold: Hypothermia in the elderly. Geriatrics 1980; 35(11):93-96.
  • 12. Siegel RJ, Vislness LM & Laub DR: Use of the water bed for prevention of bed sores. Plas Recensir Sarg 1973; 51(3):596-600.
  • 13. Pfaudler M: Floatation, displacement, and decubutis ulcers. Am J Nurs 1968; 68(11):999-1003.
  • 14. Horsley J: Preventing decubitis ulcers, CURN project. New York: Grune and Stratton, 1979.
  • 15. Dewis LS, Caplan HL: Treatment of decubitis ulcers by use of a water mattress. Arch Phys Med Rehabil 1968; 49(5):290-293.
  • 16. Lotus, Information and instructions about the Lotus flotation systems.

FIGURE

MEAN DEMOGRAPHIC DATA OF CLIENTS ACCORDING TO TYPE OF MATTRESS

10.3928/0098-9134-19870501-05

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