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 what the patient’s wishes would be regarding the use of NIV or transfer to intensive care - there may be an advanced directive in place, or they may express the wish not to receive NIV / ICU ventilation in the event of deterioration if they are initially stable enough to have this conversation.

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 1 hour), nebulised salbutamol when required, corticosteroids, antibiotics if appropriate, controlled FiO₂ (usually 28% venturi mask - aim for O₂ saturation 86-90%), and reversal of respiratory depressants.
• Moderate to severe dyspnoea, RR >25bpm.

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 and the patient is not for ICU / intubation.)

Step 3 - Patient for ICU / intubation?

• Flowchart Algorithm to determine if the patient should be transferred to ICU or intubated

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.

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 >30^Oangle.
3. Set ventilator settings:
   • IPAP = 10cm H₂O.
   • EPAP = 4cm H₂O.
   • RATE = 12bpm (becomes active should patient stop breathing or have periods of apnoea).
   • EXPIRATION TRIGGER = 2.
   • INSPIRATION TRIGGER = 2.
   • RISE TIME = 1.
   • OXYGEN = if supplementary oxygen required, set at 4L/min and titrate as necessary to maintain SpO₂ 88-92%.
4. Increase IPAP in increments of 2cm H₂O to the maximum that patient will tolerate (usually not more than 20cm H₂O).

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 hour 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
• No improvement in CO₂
• No reduction in respiratory rate
• Patient not tolerating
• Patient refusal
• If patient is not tolerant of, or refuses NIV, rediscuss management with senior medical staff.
• If ceiling of treatment and NIV fails, refer to the Palliative Care Guidelines.
• Ensure documentation of patient and family views.

Step 7 - Weaning criteria

Is the patient ready to wean?

• Clinically stable for >6 hours
• RR <24bpm
• HR <110bpm
• H⁺ <45nmol/L
• SpO₂ >88% on 4L O₂ whilst on NIV

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)

The local respiratory unit should be involved early in the care of these patients.

Guideline reviewed June 2021