Peak Flow Monitoring

What is peak flow?

The highest flow rate generated during an FVC test

Is peak flow a common bedside test?

Yes

What does the FVC measure?

A volume of gas exhaled

What does a decreased peak flow usually indicate?

Airway obstruction

Do you need to complete an entire FVC maneuver to measure peak flow?

No

What is peak flow excellent for?

Tracking changes in airflow

What does PEF capture compared with an FVC?

Only the initial expiratory blast; it does not measure volume or capacity

What does an FVC maneuver require the patient to do?

Keep exhaling until they cannot exhale anymore

Is PEF effort dependent?

Yes. It depends on the patient’s effort and initial blast

Which condition is peak flow monitoring most commonly associated with?

Asthma

Why is peak flow monitoring useful in asthma?

Asthma is episodic and can change from day to day

Why is peak flow monitoring less suited to day-to-day changes in COPD?

COPD is more constant and does not change as much day to day

What population is specifically mentioned with peak flow monitoring?

Pediatrics

What instrument measures peak expiratory flow?

A peak flow meter

Is a peak flow meter easy to use?

Yes

Are peak flow meters considered patient friendly?

Yes

Where are peak flow meters commonly available?

RT departments and most pharmacies

What is the ATS recommended high range for a peak flow meter?

100 L/min to >700 L/min

What is the ATS recommended low range?

60–275 L/min

What accuracy is recommended for peak flow meters?

±10% of the reading or ±0.300 L/sec, whichever is greater

What is the recommended intra-instrument precision?

Less than 5% of the reading or 0.150, whichever is greater

What is the recommended inter-device precision?

Less than 10% or 0.300 L/sec, whichever is greater

What resistance should a peak flow meter have?

Less than 2.5 cmH₂O/L/sec with flows up to 14 L/sec

What units are listed for FVC?

L/sec

What units are listed for PEF?

L/min

What instructions should be included with a peak flow meter?

Clear instructions for use

What range information should come with the device?

A sheet indicating normal test ranges

What maintenance information should be provided?

Instructions for maintenance and recognizing device malfunctions

What should patients know if their readings change significantly?

The appropriate actions to take

What peak flow is associated with inability to produce an effective cough?

A patient unable to generate more than 150 L/min cannot generate an effective cough

What can a steady decline in peak flow indicate?

An impending asthma attack

What type of patients can use peak flow for self-monitoring?

Asthmatic patients

What does peak flow measure besides airway function?

Muscular effort

What size airways does peak flow primarily assess?

Large airway function

Is suspected occupational asthma an indication for peak flow monitoring?

Yes

Can peak flow monitoring help parents recognize respiratory changes?

Yes

Is exercise-induced asthma an indication for peak flow monitoring?

Yes

How long after an asthma diagnosis may peak flow monitoring be used to identify triggers?

1–2 months after diagnosis

Can peak flow monitoring assess diurnal variation?

Yes

Is peak flow monitoring indicated in patients at increased risk?

Yes

Can peak flow monitoring help improve medication use?

Yes

What can home PEF monitoring show after chronic maintenance therapy is changed?

The patient’s response to the therapy change

How can home PEF monitoring help identify asthma triggers?

By identifying relationships between PEF and specific triggers

What important baseline should home monitoring establish?

The patient’s personal best PEF

What zones can be established using the patient's personal best?

Individual traffic zones

What should the clinician do before the patient performs peak flow testing?

Explain and demonstrate the procedure

What should be done to the PEF monitor before testing?

Zero it and set the indicator to the base of the scale

What position should the patient use?

Stand up

How should the patient inhale before performing peak flow?

Rapidly and completely, but not forced

What should the patient do with their lips around the mouthpiece?

Seal their lips around it

How should the patient exhale into the peak flow meter?

With maximal force

What should be done after each attempt?

Note the indicator and write down the result

How many peak flow attempts should be performed?

At least 3 attempts

What should the patient do after being taught the procedure?

Perform a return demonstration

Does patient cooperation affect PEF results?

Yes

Does neuromuscular coordination affect PEF?

Yes

Does large-calibre airway function affect peak flow?

Yes

Does lung elastic recoil affect peak flow?

Yes

What is another performance-related factor affecting peak flow?

The learning effect

Does age affect peak flow?

Yes

Does technique affect the peak flow result?

Yes

Which PEF value is normally recorded during each session?

The best of three attempts

Which value should be recorded if testing produces bronchospasm?

Record the first result

What should be noted if repeated maneuvers produce progressively lower results?

Note that increasing maneuvers are yielding decreasing results

What time of day should PEF monitoring be performed?

In the morning

How often should peak flow monitoring normally be performed?

Daily in the morning

Should PEF be measured before or after a bronchodilator?

Before taking the bronchodilator

When should the frequency of PEF monitoring be increased?

When results are below 80% of personal best

What amount of diurnal variability suggests poor control?

Greater than 20%

When should a patient establish their personal best PEF?

When their asthma is controlled

What PEF percentage is the green zone?

Greater than 80% of personal best

What does the green zone indicate?

No symptoms/good control

What PEF percentage is the yellow zone?

50–80% of personal best

What does the yellow zone indicate?

Caution; reassess the treatment plan

What PEF percentage is the red zone?

Less than 50% of personal best

What does the red zone indicate?

Immediate action is needed

Should a patient switch between different peak flow meters?

No. They should use the same meter

How often should the peak flow meter be inspected?

Frequently

How often should the peak flow meter be replaced?

Every 2 years

How often should spirometry and peak flow measurements be compared?

Every 2 years

What should be done when a patient's peak flow meter is changed?

Re-establish the personal best

What patient-related problem can cause peak flow self-monitoring to fail?

Incorrect reading of the meter

What technique problem can interfere with self-monitoring?

Poor technique

What equipment problem can interfere with peak flow monitoring?

Device failure

What interpretation problem can interfere with monitoring?

Misinterpretation of results

What compliance rate is reported after more than 6 months?

About 6–16%

How can clinicians improve patient compliance with PEF monitoring?

Involve the patient in decisions

What emotional support can help compliance?

Reassure the patient

How can peak flow monitoring affect patient involvement in their disease?

It allows patients to take charge of the disease process

Why should the relevance of peak flow monitoring be explained?

Demonstrating its relevance can improve compliance

Should clinicians expect perfect adherence to strict monitoring schedules?

No

What body position is acceptable when performing PEF?

Standing or sitting straight up

How should the patient inhale during an acceptable maneuver?

Rapidly, but not forced

How should the patient exhale during an acceptable maneuver?

Maximally without holding their breath

How many efforts should normally be performed?

Three

What is the maximum number of efforts listed?

Five

How close should the largest two PEF efforts be for repeatability?

Within 40 L/min

Which PEF value is ultimately reported?

The largest PEF obtained

Is peak flow monitoring an objective monitoring tool?

Yes

Can peak flow be used to assess therapy?

Yes