Spirometry metrics added to Inform API

On 12/10/2019 the following spirometry metrics were added to the Inform API. With this the "peak_flow" metric has been depreciated and replaced with "pef".

TypeDefinitionData TypeStandard Units
fef_25_75Forced expiratory flow (FEF) over the middle one half of the Forced Vital Capacity (FVC); the average flow from the point at which 25 percent of the FVC has been exhaled to the point at which 75 percent of the FVC has been exhaled,floatL/s
fetForced Expiratory Time (FET) measures the length of the expiration.floatms
fev1Forced expiratory volume (FEV1) measures how much air a person can exhale during the first forced breath.floatL
fev1_per_fvcRepresents the proportion of a person's vital capacity that they are able to expire in the first second of forced expiration (FEV1) to the full, forced vital capacity (FVC). The result of this ratio is expressed as FEV1%.floatpercent
fvcForced vital capacity (FVC) is the total amount of air exhaled during the FEV test.floatL
pefThe peak expiratory flow (PEF), also called peak expiratory flow rate (PEFR), is a person's maximum speed of expiration, as measured with a peak flow meter.floatL/s