Current issues of ACP Journal Club are published in Annals of Internal Medicine


Air suspension bed and prevention of pressure ulcers

ACP J Club. 1993 July-Aug;119:19. doi:10.7326/ACPJC-1993-119-1-019

Source Citation

Inman KJ, Sibbald WJ, Rutledge FS, Clark BJ. Clinical utility and cost-effectiveness of an air suspension bed in the prevention of pressure ulcers. JAMA. 1993 Mar 3;269:1139-43.



To evaluate the effectiveness of an air suspension bed in the prevention of pressure ulcers in critically ill patients.


Randomized controlled trial.


30-bed intensive care unit (ICU) in London, Ontario.


100 consecutive patients > 17 years of age with an expected stay in the ICU of ≥ 3 days and an Acute Physiology and Chronic Health Evaluation II (APACHE II) score > 15 on admission. 98 patients (mean age 64 y, 52% men) completed the study.


49 patients were randomized to receive treatment with the air suspension bed, and 49 patients were allocated to a standard ICU bed. Patients randomized to the standard bed were rotated every 2 hours unless contraindicated.

Main outcome measures

Development of pressure ulcers by site and severity. Illness severity was assessed by calculating the APACHE II score at 24 and 72 hours after ICU admission. Nursing care intensity was estimated daily with the Therapeutic Intervention Scoring System (TISS). Physiologic variables were collected daily.

Main results

39 pressure ulcers were detected in the standard-bed group compared with 8 in the air-suspension-bed group. The sacrum-trochanter was the most common site of the ulcers. Multiple logistic regression analysis showed that fewer patients in the air-suspension-bed group developed single (odds ratio [OR] 0.18, 95% CI 0.08 to 0.41), multiple (OR 0.11, CI 0.02 to 0.54), or severe (OR 0.16, CI 0.06 to 0.44) ulcers. Other predictors of single pressure-ulcer development included length of ICU stay (OR 1.07, CI 1.03 to 1.12), 72-hour APACHE II score (OR 1.12, CI 1.03 to 1.21), 72-hour total serum albumin level (OR 0.85, CI 0.74 to 0.97), and admission TISS score (OR 0.92, CI 0.87 to 0.98). With the exception of the TISS and APACHE II scores, similar results were found for the model predicting multiple pressure-ulcer development. In addition to an air suspension bed, length of ICU stay and admission TISS score were predictors of severe pressure ulcers.


Fewer critically ill patients in the intensive care unit developed pressure ulcers using an air suspension bed than with a standard intensive care unit bed.

Source of funding: Kinetic Concepts, Inc.

For article reprint: Mr. K.J. Inman, Management and Evaluative Research Group, London Health Sciences Center, Room 482 NW, 375 South Street, London, Ontario N6A 4G5. FAX 519-667-6698.


We frequently view pressure sores as a problem in nursing homes. One of the highest reported incidences, however, was 28.6 per 1000 patient days for all admissions to an adult ICU (1, 2). By selecting patients with an Apache II score > 15, Inman and colleagues identified a subgroup with the even greater incidence (calculated from controls) of 51.7 per 1000 patient days. Despite the plethora of pressure-relieving devices available, little evidence exists for prevention efficacy through randomized clinical trials (2). This is the only report of a randomized trial of low air-loss beds for the prevention of pressure sores, and the results are impressive.

A frequent objection to special beds is their cost. The authors also presented data suggesting that these beds are cost effective. Cost analysis is difficult because of limited information on the treatment costs of pressure sores. Less costly pressure-relieving devices, such as mattresses and pads having similar pressure-relieving characteristics (3), are available but have not been tested in randomized clinical trials.

Patients at the highest risk for developing pressure sores should be provided with some type of pressure-relieving device. We now have evidence that low air-loss beds are effective, justifying increased use. For cost containment, less costly devices may be considered. We look forward to randomized trials done as well as this one to provide comparison evidence for efficacy.

David M. Smith, MD
Regenstrief Institute for Health Care Indianapolis, Indiana, USA