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Peak flow meter Exam OSCE

Apr 06, 20257 min read

Peak Flow Meter (PFM)

Table of Contents

Overview and Purpose

  • Name: Peak Flow Meter (PFM)
  • Purpose:
    • Tells you how well your lungs are working with the current medications.
    • Measures Peak Expiratory Flow (PEF) or Peak Expiratory Flow Rate (PEFR) in Liters per minute (L/min).
    • Serves as an early warning sign of asthma deterioration.
  • Goal: To help monitor asthma control and guide treatment adjustments based on an action plan.

Device Components

  • Show the patient the instrument and explain its parts:
    • Clear plastic body
    • Logarithmic scale (measures flow rate)
    • Internal flow indicator/pointer
    • Color zones (often marked on the meter or used in the action plan chart)
    • Mouthpiece (disposable/cleanable)

Usage Instructions

  1. Preparation:

    • Wash hands.
    • Ensure the patient does not have food or gum in their mouth.
    • Reset the pointer/indicator on the scale to zero.
    • Attach a clean/fresh mouthpiece.

  2. Posture:

    • Stand up straight. (Sitting upright is an alternative, but standing is preferred as sitting can restrain diaphragm movement, potentially giving a falsely low reading).
    • Avoid bending the neck down.

  3. Holding the Meter:

    • Hold the meter horizontally.
    • Keep fingers clear of the scale and the slot where the pointer moves.

  4. Breathing Technique:

    • Inhale: Take a deep breath in, filling the lungs completely. Hold your breath briefly.
    • Seal: Place the mouthpiece well into the mouth, biting lightly, and seal the lips firmly around it. Ensure the tongue or teeth do not block the opening.
    • Exhale: Blow out as hard and as fast as possible in a single, short blast (like blowing out candles).

  5. Reading the Result:

    • Note the number where the pointer stopped on the scale. This is the PEF reading.
    • Write down the reading.

  6. Repeat Measurement:

    • Reset the pointer to zero.
    • Repeat steps 3-5 two more times (for a total of three blows).
    • Record the highest of the three readings in the asthma diary or chart.

  7. Check Understanding:

    • Ask the patient to demonstrate the procedure to ensure they understand and perform it correctly. Observe their technique.

Determining the Personal Best Peak Flow Number

  • Purpose: To establish the patient’s optimal lung function when their asthma is well-controlled. This number is used to set the zones for their action plan.
  • Procedure:
    • Once asthma is stable (e.g., after recovering from an attack and on effective medication), measure PEF daily for 2-3 weeks.
    • Take readings at consistent times, for example:
      • On waking (e.g., 7-9 am)
      • Midday (e.g., 12-2 pm)
      • Evening (e.g., 6-8 pm)
    • Record the highest reading of the day.
    • Also record any symptoms or events that might affect breathing (e.g., cold, exposure to triggers).
    • The highest number achieved consistently during this period is the “Personal Best” PEFR.
  • Note: Daily readings often show some variation (a zigzag pattern), which is normal. Significant drops indicate potential problems.

Peak Flow Zones and Action Plan

  • Concept: Based on the Personal Best PEFR, an action plan is developed using zones like traffic lights (Green, Yellow, Red) to guide self-management. If the Personal Best is not yet known, predicted values based on age, height, and sex can be used initially (compare value with reference chart).

  • Frequency of Monitoring: Use the PFM every morning after determining the Personal Best, and whenever symptoms occur.

  • Zones:

    • 🟩 Green Zone:

      • Reading: ≥ 80% of Personal Best PEFR.
      • Meaning: Good control. Asthma is well-managed; patient is likely asymptomatic.
      • Action: Continue routine daily long-term control medications (if prescribed). Use rescue medication as needed before exercise (if advised).

    • 🟨 Yellow Zone:

      • Reading: 50% - 79% of Personal Best PEFR.
      • Meaning: Caution. Asthma is worsening. May experience mild symptoms (coughing, wheezing, chest tightness, night waking).
      • Action:
        1. Use rescue medication (short-acting bronchodilator) as prescribed.
        2. Re-measure PEF after a short period (e.g., 20-60 minutes).
        3. If PEF returns to the Green Zone, continue monitoring.
        4. If PEF remains in the Yellow Zone, continue rescue medication as directed and contact the doctor/clinic for advice or an appointment, as medication adjustment may be needed.

    • 🟥 Red Zone:

      • Reading: < 50% of Personal Best PEFR.
      • Meaning: Medical Alert! Severe asthma flare-up. Likely experiencing significant symptoms (shortness of breath, difficulty walking/talking, decreased activity tolerance).
      • Action:
        1. Use rescue medication immediately.
        2. Take oral steroid medication if prescribed in the action plan for this situation.
        3. Call the doctor or emergency services (e.g., ambulance) immediately.
        4. If waiting for help and symptoms persist after 15 minutes, repeat rescue medication. Continue repeating rescue medication every 15 minutes until help arrives or significant improvement occurs.

Cleaning and Storage

  • Clean the peak flow meter regularly according to the manufacturer’s instructions (often involves washing the mouthpiece and sometimes the main body, ensuring it’s completely dry before reuse).
  • Store the meter in a clean, dry place, away from dirt and dust.

Follow-up and Communication

  • Discuss the readings and action plan adherence during follow-up appointments.
  • Review symptoms and adjust the treatment plan as needed.
  • Ask the patient if they have any questions.
  • Inform the patient about the date of their next visit.

Counseling Guide / OSCE Checklist

Candidate Actions

  • Preparation: Wash hands, introduce yourself, confirm patient identity, establish rapport (address patient by name).
  • Assess Understanding: Elicit the patient’s current understanding of asthma and peak flow measurement (Ideas, Concerns, Expectations - ICE).
  • Explain Device:
    • Clearly state the name: Peak Flow Meter (PFM).
    • Explain the purpose in simple terms (monitoring lung function, early warning).
    • Show the device and identify its parts.
  • Demonstrate Use:
    • Explain and demonstrate each step of the usage instructions clearly (posture, zeroing, holding, inhaling, sealing lips, blowing hard and fast, reading, repeating x3, recording highest).
  • Patient Practice: Allow the patient to perform the measurement under observation. Provide feedback and correct technique as needed.
  • Explain Personal Best: Describe how and why to determine the Personal Best PEFR.
  • Explain Zones & Action Plan: Explain the Green, Yellow, and Red zones, what readings correspond to each (based on personal best or predicted), what they mean, and the specific actions required for each zone.
  • Explain Monitoring Schedule: Advise on when to use the PFM (e.g., daily morning, when symptomatic).
  • Explain Maintenance: Advise on cleaning and storage.
  • Check Overall Understanding: Summarize key points, ask the patient to explain back the plan, and invite questions.
  • Plan Follow-up: Mention the need for review and schedule the next appointment.

Doctor/Patient Interaction / Effective Use of Consultation

  • Rapport & Respect: Use appropriate non-verbal behavior (eye contact, posture, position, movement, expression). Show interest, concern, and respect.
  • Information Gathering: Use open and closed questions appropriately. Elicit patient’s perspective (ICE).
  • Active Listening: Listen attentively, allow patient time to speak and think, use silence effectively.
  • Facilitation: Encourage patient responses verbally and non-verbally.
  • Clear Communication: Use concise, easily understood language; avoid or explain jargon.
  • Summarization: Periodically summarize to verify understanding and invite corrections.
  • Shared Decision Making: Involve the patient in understanding their role in management.
  • Structure & Timing: Manage the consultation time effectively.

Reference Values (General)

  • Normal Range (Adults): Varies significantly based on age, sex, and height. Typical ranges might be roughly 400-700 L/min, but personal best is the most important reference for an individual with asthma.
  • Threshold Interpretation: A reading less than 80% of personal best often indicates worsening control (Yellow Zone). A reading less than 50% indicates a medical alert (Red Zone). (Note: The original text’s point “If he was less than 80 → Asthmatic” is likely a misinterpretation; PEF is used for monitoring diagnosed asthma, not typically for initial diagnosis, and the threshold refers to % of best/predicted, indicating control level).

Graph View

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