Differences in Prediction Formulas for the MVV According to the Status of Ventilatory Function

Kang, Tae Kyung; Park, Ki Soo; Park, Jun Goo; Won, Jun Hee; Kim, Chang Ho; Park, Jae Yong; Jung, Tae Hoon

Abstract

OBJECTIVES
The MVV reflects subjective dyspnea, exercise capacity, postoperative complication. But, the MVV embodies certain disadvantages and is dependent on coordination, endurance and motivation. A timed vital capacity for calculation of an indirect maximal voluntary ventilation is used. We evaluated differences in prediction formulas for the MUV according to the status of ventilatory function.
METHODS
Forty-seven normal subjects, 68 patients with obstructive ventilatory impairment, and 23 patients with restrictive ventilatory impairment were studied. The relationships between the MVV and Flow or time parameters in forced expiratory volume and flow volume curves were compared among normal subjects and patients with obstructive or restrictive ventilatory impairment.
RESULTS
1) High correlation coefficients(R>or=0.87) were found between the FEV0.5, 0.75, 1 and the MVV in 47 normal subjects and 91 patients with ventilatory impairment. 2) The MVV can be conveniently estimated from the FEV1 values. The following regression formulas for the prediction of the MVV were obtained. Normal: MVV=44.01 X FEV1-21.09(r(2)=0.771, SEE=11.085) Obstructive ventilatory impairment: MVV=38.34 X FEV1-4.58(r(2)0.812, SEE=4.816) Restrictive ventilatory impairment: MVV=45.20 X FEV1-3.80(r(2)=0.899, SEE=6.929). 3) There were significant differences in prediction formulas for the MVV obtained by FEV1 between each group (P<0.05).
CONCLUSION
These results suggest that different prediction formulas for the MVV, by multiplying the FEV1 by a constant, are respectively required in normal subjects and patients with obstructive or restrictive ventilatory impairment.