TY - JOUR
T1 - Dynamic properties of body plethysmographs and effects on physiological parameters
AU - John, J.
AU - Drefeldt, B.
AU - Taskar, V.
AU - Mansson, C.
AU - Jonson, B.
PY - 1994
Y1 - 1994
N2 - A model incorporating compliance, resistance, inertia, and the thermal time constant of plethysmographs is used to describe the effect of its dynamic properties on measured respiratory parameters. Using numerical simulation we studied the effect of distortion of flow signals from 13 infants in whom flow and esophageal pressure had been recorded. The distortion in amplitude, shape, and timing of the recorded flow patterns was dependent on the dynamic properties of the plethysmograph. For constant- volume 'pressure' plethysmographs, errors of derived parameters such as compliance and resistance are very important if the thermal time constant is short. These errors are not corrected by calibrating the plethysmograph at the breathing frequency. Time correction of the flow signals in volume- displacement plethysmographs gives accurate results when the plethysmograph resistance and compliance are low. Overall, a volume-displacement plethysmograph with moderately high resistance of the flowmeter, corrected for internal pressure and inertia, gives the best possible results.
AB - A model incorporating compliance, resistance, inertia, and the thermal time constant of plethysmographs is used to describe the effect of its dynamic properties on measured respiratory parameters. Using numerical simulation we studied the effect of distortion of flow signals from 13 infants in whom flow and esophageal pressure had been recorded. The distortion in amplitude, shape, and timing of the recorded flow patterns was dependent on the dynamic properties of the plethysmograph. For constant- volume 'pressure' plethysmographs, errors of derived parameters such as compliance and resistance are very important if the thermal time constant is short. These errors are not corrected by calibrating the plethysmograph at the breathing frequency. Time correction of the flow signals in volume- displacement plethysmographs gives accurate results when the plethysmograph resistance and compliance are low. Overall, a volume-displacement plethysmograph with moderately high resistance of the flowmeter, corrected for internal pressure and inertia, gives the best possible results.
KW - body plethysmography
KW - inertia
KW - pressure correction
KW - thermal time constant
KW - time correction
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U2 - 10.1152/jappl.1994.77.1.152
DO - 10.1152/jappl.1994.77.1.152
M3 - Article
C2 - 7961228
AN - SCOPUS:0028277767
SN - 8750-7587
VL - 77
SP - 152
EP - 159
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -