Non-Invasive Ventilation (NIV) Protocol in COPD

AIM = To ensure patients are correctly and promptly identified as candidates for NIV.

Step 1

  • History
  • Examination
  • CXR
  • Arterial Blood Gases (ABGs)
  • Establish the premorbid functional status of the patient if possible as this may influence subsequent decisions regarding suitability for management in higher dependency / intensive care settings.
  • Establish the treatment escalation plan as far as practical. Consider what the patient’s wishes would be regarding NIV or transfer to intensive care, their functional status and the likelihood of recovery to a quality of life acceptable to the patient. This can be difficult in the acute setting and may need clarification whilst the patient is receiving NIV.

Is the patient a candidate for NIV?

  • Does the patient have a diagnosis of COPD?
  • Does the patient have an acidotic exacerbation of COPD?
  • If 'NO' to either of the above then discuss with senior medical staff suitability for NIV.
  • Physiological criteria: decompensated type 2 respiratory failure i.e. pH <7.35 (H+ >45nmol/L) and pCO2 >6kPa.
  • On maximum medical therapy (and has been for up to 1 hour), including nebulised bronchodilators, corticosteroids, antibiotics if appropriate, controlled FiO2 aiming for oxygen saturation of 88-92%.

Step 2 - Are there any contraindications to NIV?

Absolute contraindications:

  • Respiratory arrest / need for immediate intubation
  • Facial trauma / burns / surgery / abnormalities
  • Fixed upper airway obstruction
  • Severe vomiting
  • Acute severe asthma
  • Pneumothorax (unless chest drain inserted)
  • Confirmed wish by the patient not to receive NIV in the event of a deterioration.

Relative contraindications:

  • Inability to protect airway
  • Life-threatening hypoxaemia
  • Haemodynamic instability
  • Impaired consciousness
  • Confusion / agitation
  • Bowel obstruction
  • Recent facial / upper airway or upper GI tract surgery
  • Copious respiratory secretions
  • Pneumonia

(NIV may be used despite relative contraindications if this is the ceiling of treatment)

Step 3 - Patient for referral to ICU for invasive ventilation?

Should the patient be referred now rather than after a trial of NIV? Consider illness severity, patient conscious level and the presence of contraindications.

Step 4 - Initiation of NIV

AIM = To ensure patients are correctly and safely initiated on NIV.

Arterial blood gases must be checked prior to starting NIV and whilst the patient is on controlled FiO2. NIV should be administered in ED resus, Medical HDU or Medical High Care.

  1. Size for face mask (select the smallest mask that fits comfortably):
    • small leaks are permitted but not into the eyes.
    • assess mask fit by monitoring mask leak, aim to keep any leaks to a minimum.
    • demonstrate use of quick release strap.
    .
  2. Position the patient in bed or chair at >30O angle.
  3. Set ventilator settings:
    • IPAP = 10cm H2O.
    • EPAP = 4cm H2O (obese patients may require a higher EPAP if they do not respond to initial settings).
    • RATE = 12bpm (becomes active should patient stop breathing or have periods of apnoea).
    • EXPIRATION TRIGGER = 2.
    • INSPIRATION TRIGGER = 1.5.
    • RISE TIME = 2.
    • OXYGEN = to achieve target oxygen saturations of 88-92%.
  4. Increase IPAP in increments of 2cm H2O every 2-5 minutes aiming for 20cm H2O or to the maximum that patient will tolerate.

Step 5 - Monitoring the patient on NIV

Record observations on NIV Observation Chart every 15 minutes for the first hour, evaluate thereafter:

  • SpO2 - continuous monitoring with pulse oximeter.
  • ABGs - 1, 4 and 12 hours post commencement of NIV, thereafter evaluate as per patient's condition (if ABGs worsening after 4-6 hours then this is a poor prognostic factor for NIV).
  • Respiratory rate.
  • Heart rate.
  • Evaluate accessory muscle use.
  • Chest wall movement (to ensure adequate ventilation).
  • Synchrony with the ventilator and air leaks.

Step 6 - Treatment failure

  • Indications of failure:
    • No improvement in acidosis or CO2
    • No reduction in respiratory rate, oxygenation or heart rate
    • Patient not tolerating
    • Patient refusal
  • If patient is not tolerant of, or refuses NIV, re-discuss management with senior medical staff. For many patients, continuing standard medical therapy with controlled oxygen, nebulised bronchodilators and steroids will be appropriate.
  • If NIV is the ceiling of treatment and the patient is deteriorating despite this, then consider if the patient is approaching end of life. NIV should be withdrawn in dying patients. Consider referring to the Palliative Care Guidelines.

Step 7 - Weaning criteria

Is the patient ready to wean?

  • Clinically stable for >6 hours
  • RR <24bpm
  • HR <110bpm, unless there is an alternative cause for the tachycardia e.g. AF
  • Improving acidosis
  • Improving or low oxygen requirement

If 'NO' to the above:

  • Continuous NIV (monitor as before)

If 'YES' to the above:

  • Allow breaks for meals, medication, physiotherapy etc
  • Consider nocturnal NIV only
  • Controlled O2 therapy

If worsening respiratory distress, reassess patient, review therapy and consider recommencing NIV.

Patients on home NIV

Some patients use NIV chronically at home. Typical reasons are:

  • Chronic hypercapnic respiratory failure:
    • obesity hypoventilation
    • chest bellows disease
    • neuromuscular disease
    • occasionally COPD
  • Palliation in motor neurone disease (MND / ALS)

Patients on home NIV who are admitted for a non-respiratory illness should be asked to arrange for their own machine to be brought to hospital so they can continue NIV as an inpatient (this can be undertaken on the general ward). Patients on home NIV admitted with a respiratory illness may require additional respiratory support from a hospital NIV machine - consult the local respiratory unit and/or critical care team early.

 

Guideline reviewed September 2023
Page updated September 2023



;