MECHANICAL CHEST STIMULATION AS A PHYSIOTHERAPY AID

In patients with lung disorders there is often a build up of mucus ins ide the lungs which in healthy people is normally removed by the actio n of cilia on the lung tissue surfaces. In the diseased lung, however, this clearance mechanism mag be ineffective and so patients are offer ed physiotherapy in order to assist the mucus removal process. The con sequences of not properly removing the mucus are impaired lung functio n and a much higher risk of contracting lung infections and suffering consequent permanent scarring of the lung tissues. If unchecked the la tter leads ultimately to failure of the lungs and to the patient's dea th. The most common forms of chest physiotherapy wed are percussion co upled with postural drainage and an active cycle of breathing. This re quires the patient to lie head downwards on an inclined surface, so th at gravity might assist the mucus removal process, whilst the physioth erapist strikes the patient's chest with the hands. The procedure is i nterspaced by periods of 'huffing and coughing' by the patient to remo ve the loosened sputum from the body. An alternative to the manual per cussion described above is to use machinery to provide the stimulus to the chest. If such a Procedure mere found to be satisfactory then it would enable more patients to manage their own physiotherapy, may make the required duration of the physiotherapy sessions shorter, and woul d free much of the professional physiotherapists' time to enable them to assume more of a physiotherapy management role. Methods that have b een investigated to this end include the use of mechanical vibrators t o shake the chest, the use of inflated vests to deliver a stimulus via air pressure pulsations (known as 'external chest wall compression'), and internal excitation of the body tissue by delivering air pulses t o the body via the mouth or nose (known as 'oral/nasal high frequency oscillation'). The aim of this paper is to review the research that ha s been undertaken to date using such techniques, and to point in the d irection of likely beneficial future developments.