Mechanical mobility of the thorax for continuous determination of lung gas volume [ 2003 - 2004 ]

Research Grant

Researchers: Malcolm Wilkinson (Principal investigator) ,  A/Pr Philip Berger ,  C Andrew Ramsden

Brief description Percussion is a valuable clinical method for physical examination of parts of the body. A sharp tap (impulsive force) is applied to the body wall and the sound radiated in response is observed. This sound may be dull (over liver) or stony dull (pleural effusion), or resonant (over normal lung) or hyper-resonant (over bowel). While the variation in radiated sound is not fully understood, it is apparent that the presence of gas, which is highly compliant, increases mobility of the overlying tissue and allows it to resonate; where the sub-tissue is largely fluid, tissue mobility is low and the percussive sound is dull. Percussion is useful for examining the adult chest and lung, but cannot for example be applied in infant intensive care as only limited impulsive force can be used, and the adult finger, which is both a coupling device and sounding board, is too large. As well, percussion requires skill and quiet conditions. Accordingly, we developed a device to measure mobility of the chest and other tissues in real time. The VibroPulse applies a known low-level force to the body surface and records the resultant velocity induced in the surface. The force is generated by a vibrating mass set in motion by an electromagnetic motor driven by pseudo-random noise. Tissue mobility, defined as velocity-force, is derived simultaneously across the frequency range, providing an easily interpreted quantitative output unaffected by ambient noise. This proposal has two aims we can achieve in 1 year: (1) to continue evaluating VibroPulse sensitivity to tissue composition, using symmetrical percussive sites on the human chest and abdomen that are dull on one side and resonant on the other, and the chest of anaesthetised animals with experimentally induced pneumothorax and lung collapse, two life-threatening conditions for which percussion is a key diagnostic method, and (2) to engineer a small device from our bulky prototype that is suitable for clinical use, in infants and adults.

Funding Amount $AUD 165,000.00

Funding Scheme NHMRC Development Grants

Notes Development Grant