Assessing Obstructive and Restrictive Patterns

Sudjoko KUSWADJI

Overview It is often possible to recognize patterns associated with obstructive or restrictive lung disease based on the results of pulmonary function testing.

With obstruction:Patients may have a normal or modestly reduced vital capacity, but the volume time tracing of the forced vital capacity will be abnormal.There is flattening of the slope of the curve at any given lung volume, reflecting reduced rate of airflow.The duration of the forced expiratory maneuver is prolonged; the changes in the rate of expiratory airflow reduce the FEV1, FEV3, FEV1-to-FVC, FEV3-to-FVC, and FEF(25-75%).In small airway disease: FVC is >= 81% of predicted, but FEF(25-75%) < 65%.

Pasien mungkin memiliki kapasitas vital normal atau sederhana berkurang, namun volume waktu penelusuran kapasitas vital paksa akan abnormal. Ada merata dari kemiringan kurva pada setiap volume paru-paru yang diberikan, mencerminkan penurunan laju aliran udara. Durasi manuver ekspirasi paksa berkepanjangan, perubahan dalam tingkat aliran udara ekspirasi mengurangi FEV1, FEV3, FEV1-to-FVC, FEV3-to-FVC, dan FEF (25-75%). Pada penyakit saluran napas kecil: FVC adalah> = 81% dari yang diperkirakan, namun FEF (25-75%)

FEV1Interpretation> 80% predictednormal66-80% predictedmild obstruction50-65% predictedmoderate obstruction< 50% predictedsevere obstruction

FEV1 to FVC ratioInterpretation>= 70% of predictednormal61 - 69% of predictedmild obstruction45 - 60% of predictedmoderate obstruction< 45% of predictedsevere obstruction

FEF(25-75%)Interpretation>= 66% of predictednormal50 - 65% of predictedmild obstruction35 - 49% of predictedmoderate obstruction< 35% of predictedsevere obstruction

With restriction:The configuration of the volume-time tracing may not be abnormal.The FEV1 and FEV(3) are low because of the reduced vital capacity.The FEV1-to-FVC and FEV(3)-to-FVC are normal or even increased.The FEF(25-75%) is lower than predicted.By examining the ratio of measured-to-predicted lung capacities it is possible to assess the severity of restrictive lung disease.

Konfigurasi volume-time tracing mungkin tidak normal. The FEV1 dan FEV (3) rendah karena kapasitas vital berkurang. FEV1-to-FVC dan FEV (3)-to-FVC normal atau bahkan meningkat. The FEF (25-75%) lebih rendah dari yang diperkirakan. Dengan memeriksa rasio kapasitas paru diukur-ke-prediksi adalah mungkin untuk menilai keparahan penyakit paru restriktif.

VC (vital capacity)Interpretation>= 81% of predictednormal66 - 80% of predictedmild restriction51 - 65% of predictedmoderate restriction

where:The forced vital capacity (FVC) is reported by some to be equivalent to vital capacity (VC).di mana: kapasitas vital paksa (FVC) dilaporkan oleh beberapa orang untuk menjadi setara dengan kapasitas vital (VC).

TLC (total lung capacity)Interpretation>= 81% of predictednormal66 - 80% of predictedmild restriction51 - 65% of predictedmoderate restriction

References: Fishman A (editor). Pulmonary Diseases and Disorders, Second Edition. McGraw-Hill Book Company. 1988. pages 2483 and 2510Murray J, Nadel J. Textbook of Respiratory Medicine, 2nd edition. W.B. Saunders Company. 1994. page 871