Non-Invasive Ventilation (NIV) Protocol in COPD
AIM = To ensure patients are correctly and promptly identified as candidates for NIV.
- 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 / ITU 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?
- 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.
- 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
(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?
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.
- 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.
- Position the patient in bed or chair at >30Oangle.
- 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%.
- 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.