
PULMONARY

Gravity is the single most important factor responsible for uneven distributions of ventilation and blood flow in the healthy lung.
The effect of gravity on the upright lung and the resulting gradients of ventilation and perfusion from top to bottom have been well documented.[1,2]
The Total Lift Bed allows clinicians to position patients in all traditional modes; including cardiac chair position. However the TLB is the only hospital bed in the world that also allows for one very important position that consequently benefits the lungs; the standing position. The TLB's patented moving footboard actually moves to the patients feet providing support while being tilted anywhere from 0° to 82° safely and securely with one staff member; simply with the push of a button.
LUNG VOLUME CHANGES
STRUCTURAL CHANGES
- When a person is mobile, the airways of the lower respiratory tract are coated evenly with a thin layer of mucus, which keeps the airways moist and traps particles that have been inhaled.
- Contaminated mucus is continually being swept upwards by rhythmic beating of cilia on the lining of the respiratory tract (the ciliary escalator) and, when it reaches the pharynx, it is swallowed to be sterilized by the acid in the stomach.
- When a patient is confined to bed there is a tendency for mucus to pool, under the influence of gravity, in the lower part of the airway.[4] These accumulated secretions can swamp the lower portion of the ciliary escalator, reducing its function.
- These effects are often compounded in bedridden patients by dehydration, leading to the pooled mucus becoming thick and difficult to expectorate.
- The diameter of the airways, particularly the bronchioles, decreases after a period of immobility. Even healthy people can show airway narrowing after being in the supine position for some time; this is more pronounced in people who are older, overweight or smokers.[6]
- This reduction in airway size, together with pooled mucus and the extra weight the recumbent body places on the rib cage, combine to make breathing more labored, and patients tend to take fewer deep breaths.
- The results can include the collapse of airways and small areas of lung tissue (atelectasis), which reduces the area available for gaseous exchange.[4]
- Many studies have shown that prolonged bed rest dramatically increases the risk of respiratory tract infections. People cannot cough as easily or as well, which allows pooled mucus to stagnate and reduces the clearance of potentially pathogenic material and irritants.
- Stroke patients confined to bed for 13 days or more are two to three times more likely to develop respiratory tract infections compared with mobile people.[5]
- Frequently turning and repositioning patients can help to prevent abnormal distribution and pooling of mucus in the respiratory tract. Bedridden patients can also be encouraged to try cough exercises to help shift pooled mucus and reduce the chance of an infection.
REFERENCES
- Martin CJ, Young AC: Ventilation-perfusion variations within the lung. J Appl Physiol 11:371-376,1957
- Glaister DH: The effect of posture on the distribution of ventilation and blood flow in the normal lung. Clin Sci 33:391-398, 1967
- Corcoran, P.J. (1991) Use it or lose it: the hazards of bedrest and inactivity. Western Journal of Medicine; 54: 5, 536 - 538.
- Corcoran, P.J. (1981) Disability consequences of bed rest. In: Stolov, W.C., Clowers, M.R. (eds) Handbook of Severe Disability: A Text for Rehabilitation Counselors, Other Vocational Practitioners, and Allied Health Professionals. Washington, DC: United States Government Printing.
- Halar, E.M. (1994) Disuse syndrome: recognition and prevention. In: Hayes, R.M. et al (eds) Chronic Disease and Disability: A Contemporary Rehabilitation Approach to the Practice of Medicine. New York: Demos Medical Publishing.
- Dean, E. (1985) Effect of body position on pulmonary function.Physical Therapy; 65: 5, 613 - 618.
- Manning, F. et al (1999) Effects of side lying on lung function in older individuals. Physical Therapy; 79: 5, 456 - 466.
Products
- Total Lift Bed
425lb/192KG. Weight Capacity Tilts a patient from a 0° flat position to an 82° fully upright position, and any degree in-between.