ATS/ERS Task Force Algorithm - Spirometry

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FIGURE 2. A simplified algorithm that may be used to assess lung  function in clinical practice. It presents classic patterns for various  pulmonary disorders. As in any such diagram, patients may or may not  present with the classic patterns, depending on their illnesses,  severity and lung function prior to the disease onset (e.g. did they  start with a vital capacity (VC) close to the upper or lower limits of  normal (LLN)).

The decisions about how far to follow this diagram are  clinical, and will vary depending on the questions being asked and the  clinical information available at the time of testing. The forced expiratory volume in one second (FEV1)/ VC ratio and VC should be considered first. Total lung capacity (TLC) is necessary to confirm or  exclude the presence of a restrictive defect when VC is below the LLN.  The algorithm also includes diffusing capacity for carbon monoxide (DL,CO) measurement with the predicted value adjusted for haemoglobin.  In the mixed defect group, the DL,CO patterns are the same as those for  restriction and obstruction.

This flow chart is not suitable for assessing the severity of upper airway obstruction.

PV: pulmonary  vascular; CW: chest wall; NM: neuromuscular; ILD: interstitial lung  diseases; CB: chronic bronchitis. 

FIGURE 2. A simplified algorithm that may be used to assess lung  function in clinical practice. It presents classic patterns for various  pulmonary disorders. As in any such diagram, patients may or may not  present with the classic patterns, depending on their illnesses,  severity and lung function prior to the disease onset (e.g. did they  start with a vital capacity (VC) close to the upper or lower limits of  normal (LLN)).

The decisions about how far to follow this diagram are  clinical, and will vary depending on the questions being asked and the  clinical information available at the time of testing. The forced expiratory volume in one second (FEV1)/ VC ratio and VC should be considered first. Total lung capacity (TLC) is necessary to confirm or  exclude the presence of a restrictive defect when VC is below the LLN.  The algorithm also includes diffusing capacity for carbon monoxide (DL,CO) measurement with the predicted value adjusted for haemoglobin.  In the mixed defect group, the DL,CO patterns are the same as those for  restriction and obstruction.

This flow chart is not suitable for assessing the severity of upper airway obstruction.

PV: pulmonary  vascular; CW: chest wall; NM: neuromuscular; ILD: interstitial lung  diseases; CB: chronic bronchitis.