Comparison of peak cough flows measured by pneumotachograph and a portable peak flow meter.
OBJECTIVE
To compare peak cough flows (PCF) obtained with a pneumotachograph (PCFp) with those measured using a portable peak flow meter (PCFm) in a population of healthy subjects and patients with neuromuscular disease.


METHODS
A total of 30 healthy subjects and 32 medically stable patients with neuromuscular diseases were studied. Using an oronasal mask connected, in a randomized order, to a pneumotachograph and to a portable peak flow meter, PCFp and PCFm were measured as every subject performed maximal cough efforts from total lung capacity.


RESULTS
PCFp measurements were 377.70 +/-179.28 liters/min and PCFm measurements were 377.50 +/- 172.98 liters/min (not significant). The two measurements were correlated (r = 0.95, P < 0.001). The random error obtained was 9.37%. The mean of the differences between the values obtained using both instruments +/- limits of agreement (+2 SD) was 0.20 +/- 109.78 liters/min (not significant). When the agreement was tested over three ranges of flows (< 270 liters/min, 270-480 liters/min, and >480 liters/min), no statistically significant differences were obtained for the population as a whole in any range; however, in the lower flow range, 14 patients had PCFm significantly greater than PCFp (213.93 +/- 55.92 vs. 180.86 +/- 57.22, P = <0.01).


CONCLUSIONS
PCF measurements made with a portable peak flow meter such as the asmaPLAN+ (Vitalograph, Ennis, Ireland) are reproducible and reasonably accurate when flows are >270 liters/min. However, some caution must be exercised in clinical practice at lower PCF because of the tendency of this portable device to overestimate the lower flows.
Unidad de Rehabilitación y Ventilación, Hospital Clínico Universitario, Universitat de Valéncia, Valencia, Spain.
Jesús
J
Sancho
Emilio
E
Servera
Juan
J
Díaz
Julio
J
Marín
D000293:Adolescent; D000328:Adult; D000368:Aged; D003371:Cough / Q000503:physiopathology*; D005260:Female; D045268:Flowmeters; D006801:Humans; D008297:Male; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000503:physiopathology*; D010366:Peak Expiratory Flow Rate