PFT 2

FVC

Maximum volume of air exhaled forcefully and rapidly after maximal inspiration.

FEV1

Volume of air exhaled during the first second of an FVC maneuver.

FEVT

Volume of gas expired during a specified time from the start of an FVC maneuver.

FEV1/FVC

Percentage of FVC exhaled during the first second; used to detect obstruction.

Normal FEV1/FVC

70-75%.

FEF 25-75%

Average flow rate during the middle half of the FVC maneuver; reflects small-to-medium airway function.

FEF 200-1200

Average flow between 200 and 1200 mL of exhaled volume; reflects large airway flow.

PEFR

Maximum flow rate achieved during an FVC maneuver.

Instantaneous Flow Rates

Flow measured at a specific lung volume during expiration.

MVV

Largest volume of air breathed in and out during 12-15 seconds with maximal effort.

Normal MVV Breathing Rate

90-110 breaths per minute.

MIP

greatest negative pressure generated during inspiration against an occluded airway.

MEP

greatest positive pressure generated during expiration against an occluded airway.

Normal MIP

-50 to -75 cmH2O.

Adequate MIP for spontaneous breathing

-30 cmH2O or more negative.

Normal MEP

80-100 cmH2O.

Raw

Airway resistance.

sGaw

Specific airway conductance; airway conductance corrected for lung volume.

Primary Use of Spirometry

Assess ability to move large volumes of air quickly and identify obstruction.

Indications for Spirometry

Diagnose disease, assess severity, evaluate therapy, surgical risk, disability assessment.

Most Common Adverse Reaction to Spirometry

Syncope/lightheadedness.

Contraindication to Spirometry

Recent myocardial infarction.

Most Important Patient Data for Spirometry

Height.

Required Exhalation Time During FVC

At least 6 seconds.

Minimum Number of Acceptable FVC Maneuvers

3.

Repeatability Requirement for FVC

Two largest FVC values must be within 150 mL.

Repeatability Requirement for FEV1

Two largest FEV1 values must be within 150 mL.

Good Start to Test

Rapid, forceful expiration with minimal hesitation.

Acceptable Extrapolated Volume

Less than 5% of FVC.

End-of-Test Criteria

At least 6 seconds of exhalation and/or obvious plateau.

Obstructive Disease Examples

Asthma, COPD, emphysema, chronic bronchitis, cystic fibrosis.

Restrictive Disease Examples

Pulmonary fibrosis, obesity, neuromuscular disease, chest wall disorders.

Obstructive Pattern on Spirometry

FEV1 decreased and FEV1/FVC decreased.

Restrictive Pattern on Spirometry

FVC decreased and FEV1/FVC normal or increased.

FEV1/FVC Less Than 70%

Indicates airflow obstruction.

Flow-Volume Loop in Obstruction

Scooped-out expiratory curve.

Flow-Volume Loop in Restriction

Small loop shifted to lower lung volumes.

Significant Bronchodilator Response

Increase in FEV1 or FVC greater than 12% and 200 mL.

Purpose of Pre/Post Bronchodilator Testing

Determine reversibility of airway obstruction.

How Long to Wait After Short-Acting Bronchodilator

10-15 minutes.

MIP Procedure

Exhale to RV, occlude airway, inspire forcefully for 1-3 seconds.

MEP Procedure

Inhale to TLC, occlude airway, exhale forcefully for 1-2 seconds.

MIP Measures

Inspiratory muscle strength.

MEP Measures

Expiratory muscle strength and cough effectiveness.

Low MEP Indicates

Inability to cough effectively.

MVV Can Be Estimated By

FEV1 × 40.

Normal FEV1 Predicted

80-120%.

Mild Obstruction FEV1

70-79% predicted.

Moderate Obstruction FEV1

60-69% predicted.

Moderately Severe Obstruction FEV1

50-59% predicted.

Severe Obstruction FEV1

35-49% predicted.

Very Severe Obstruction FEV1

Less than 35% predicted.

PEFR Depends On

Patient effort.

Submaximal Inspiration Causes

Reduced FVC, FEV1, and PEFR.

Cough During First Second

Test is unacceptable.

Obstruction Causes

Airway narrowing, bronchospasm, mucus, inflammation, loss of elastic recoil.

Restriction Causes

Reduced lung volumes and lung expansion.

What does an extrapolated volume alert mean after doing a spirometry?

didn’t blow fast enough at begining of test or hesitated

What is an adverse reaction to spirometry?

chest pain

What is normal FEV!/FVC ratio?

70-75

Definition of PEFR

highest flow reached during FVC maneuver

What is an obstructive disease process?

Cystic Fibrosis

What is the most important parameter in determining patients predicted normal values?

height

how long should you wait after giving bronchodilator to retest?

15 min

Normal MEP values

80-100 cm H20

What should be the variance of best two FEV1 results?

no more than 150 ml