The instrument records several parameters such as FVC, FEV1, FEV1/FVC%, forced expiratory time
(FET), peak expiratory flow rate (PEFR), forced inspiratory flow at 50% of inspired volume during FVC test (FIF50%), forced expiratory flow at 50% of expired volume during FVC test (FEF50%), and peak inspiratory flow rate (PIFR) digitally in variable seconds and as percentages besides providing a computer recorded tracing.
In a previous study, the researchers reported that daily supplemental vitamin C in pregnant women who could not quit smoking improved their newborn's pulmonary function as measured by passive respiratory compliance and the time to peak tidal expiratory flow to expiratory time
The acceptability criteria of the curves adhered to the following criteria proposed by ATS (12) and BSPT (2): a retroextrapolation volume < 5% of the forced vital capacity (FVC) or 150 mL; forced expiration duration of at least 6 s; occurrence of a plateau in the volume-time curve for at least 1 s, after a minimum expiratory time
of 6 s, or a volume in the last second lower than 25 mL, and a number of 3 to 8 breaths, with at least 3 acceptable and 2 reproducible curves.
Compared with the control and the no wheeze groups, infants in the wheeze group had significantly decreased time to peak tidal expiratory flow as a percentage of total expiratory time
(TPTEF/TE) (20.1 [+ or -] 6.4% vs.
The newborns delivered to smokers taking vitamin C demonstrated a significantly increased peak tidal expiratory flow to expiratory time
(TPTEF:TE) ratio and passive respiratory compliance per kg (Crs/kg) compared to placebo.
reported less increase in respiratory effort after EMST as the degree of exercise increased, a decrease in VE and breathing frequency during exercise, and an increase in expiratory time
after EMST .
The mean expiratory time
at rest in swimmers was 1.46 [+ or -] 0.55 sec
Acoustic analysis from the last 30s of each exercise stage was analyzed from digital recordings for breathing frequency and a variable referred to as 'intensity' (obtained from the expiratory phase of the acoustic signature); which is conceptually similar to tidal volume divided by the expiratory time
. Blinded to information from respiratory gas analysis, the acoustic signature was analyzed based on the first derivative of change in breathing frequency and sound intensity.
 Children are likely to have a shorter forced expiratory time
(FET) than adults and hence the volume plateau may be completed in a shorter time: 3 s in children <6 years of age and 1 s in smaller, preschool children.
Infant pulmonary flow volume, characterized as a ratio of the time to peak tidal expiratory flow to expiratory time
, was significantly lower in the placebo group (0.345), compared with the vitamin C group (0.383) and the nonsmoking group (0.399), Dr.
The automatic selection of these targets is based on algorithms for minimal dead space and optimal expiratory time
constant provided by the lung function analyser that is communicating continuously with the ventilator's controller.
Frequently a result of asynchronous ventilation, inadequate expiratory time
, long pulmonary time constants or inadequate inspiratory flow.