What is the normal value for Total Peak Expiratory Flow (TPEF) on spirometry?

Normal Values for TPEF on Spirometry

There are no standardized normal reference values specifically for Total Peak Expiratory Flow (TPEF) as it is not a commonly reported parameter in standard spirometry testing. Instead, clinicians typically focus on other key spirometry parameters with established reference values.

Understanding TPEF in Context

TPEF (Tidal Peak Expiratory Flow) is primarily used in specialized respiratory mechanics evaluation, particularly for:

• Young children who cannot perform forced maneuvers 1
• Assessment of breathing patterns in patients with respiratory disorders
• Research settings evaluating subtle changes in respiratory mechanics

Related TPEF Parameters

When TPEF is measured, the following parameters are typically assessed:

• Time to peak tidal expiratory flow (tPTEF) - measured in seconds
• Total expiratory time (tE) - measured in seconds
• tPTEF/tE ratio - a dimensionless ratio
• Volume at peak tidal expiratory flow (Vptef) - measured in milliliters
• Expired tidal volume (Ve) - measured in milliliters
• Vptef/Ve ratio - a dimensionless ratio 1

Standard Spirometry Parameters

Instead of TPEF, standard spirometry typically reports these parameters with established reference values:

1. Peak Expiratory Flow (PEF)

   • Normal values are individualized based on age, sex, height, and ethnicity
   • Typically reported in L/min or L/s
   • Normative data available in reference charts 2

2. Forced Expiratory Volume in 1 second (FEV1)

   • Normal values individualized by age, sex, height, and ethnicity
   • Reported as absolute value and percent predicted

3. Forced Vital Capacity (FVC)

   • Normal values individualized by age, sex, height, and ethnicity
   • Reported as absolute value and percent predicted

4. FEV1/FVC ratio

   • Should be >70-80% in healthy adults
   • Should be >90% in healthy children 2
   • The lower limit of normal (LLN) is more accurate than fixed ratios and can be approximated by subtracting 10 from the age-specific predicted FEV1/FVC 3

Quality Assessment for Spirometry

For reliable spirometry results, quality assessment is essential:

• At least 3 acceptable tests with repeatability within 0.100 L or 10% of highest value (for Grade A quality) 2
• Good start of exhalation with extrapolated volume <5% of FVC or 0.150 L
• Free from artifacts
• No cough during first second of exhalation (for FEV1)
• No early termination or cutoff (for FVC) 2

Clinical Implications

When evaluating respiratory function:

• PEF has higher intrinsic variability than FEV1 4
• For screening purposes in primary care, PEFR monitoring is non-inferior to FEV1 monitoring with comparable overall accuracy (0.94 vs 0.96) 5
• In patients with airflow limitation, the rise time and dwell time for PEF are typically shorter than in normal subjects 6

Important Caveats

1. Simple "rules of thumb" like using <80% of predicted as abnormal are inaccurate and can lead to misclassification 3
2. There is considerable overlap in TPEF values between healthy individuals and those with respiratory disorders, limiting its diagnostic specificity 1
3. When measuring TPEF in children, at least 10 (ideally consecutive) individual breaths should be analyzed 1
4. The coefficient of variation should be reported to assess measurement reliability, with typical intraindividual CV between 20-26% in normal subjects 1

For clinical practice, focus on established spirometry parameters with validated reference equations rather than TPEF, unless working with specific populations like preschool children who cannot perform standard forced maneuvers.