Non-Invasive Ventilation

Indications for nasal or Full face NIV

Based on the 2002 BTS Guidelines: Thorax 2002;57:192-211

Hypercapnic resp failure during an acute exacerbation of COPD with:

  1. Arterial pH <7.35
  2. Arterial PaCO2 >6kPa (if acute onset)
  3. Tachypnoea >23 breaths/min

Contraindications

Uses

  1. Acute Hypercapnic Respiratory Failure (e.g. in acute exacerbations of COPD)

  2. Cardiogenic Pulmonary oedema

  3. Respiratory failure in immunocompromised patients (e.g. pneumonia)

  4. Neuromuscular disorders (respiratory failure)

  5. Asthma (NB selected cases only - decision by respiratory physician)

Assessment

  1. Full Medical Assessment
  2. Arterial Blood Gases: pH 7.25 – 7.35, high PaCO2
  3. Optimal Medical Treatment not successful
  4. Consider commencing NIV
  5. Decide on plan if NIV fails
  6. Good outcome predicted if improvement in pH, PaCO2 and respiratory rate after 1hr of NIV
  7. ?chance of failure – High Apache score, Poor nutritional status, confusion/impaired consciousness
  8. Inform ICU of decision to commence NIV

Setting Up

  1. Consultant/Senior Decision to commence NIV
  2. NIV machine + tube + CO2 exhalation port + mask + head-cap
  3. Set NIV to S/T mode, EPAP at 4 – 5 cm H2O and IPAP at 8 cmH2O
  4. Set back-up breathing frequency to 8 – 10 breaths/minute
  5. Select appropriate size mask to fit patient
    • Nasal mask – preferable. Fits snugly around nose
    • Full Face mask – patient who mouth breathes
  6. Explain procedure to patient
  7. Hold mask in place to allow patient to familiarize themselves
  1. Attach pulse oximeter
  2. Commence NIV, holding mask in place initially
  3. Secure mask in place with straps/headgear to prevent leaks – do not attach too tightly!
  4. Reassess patient after a few minutes
  5. Check for leaks and refit mask if necessary
  6. Add O2 to maintain SpO2 <85%
  7. Instruct patient how to remove the mask and summon help
  8. Increase IPAP gradually up to about 12 - 15 cmH2O over 1 hr
  9. Clinical assessment and if appropriate check ABG at 1 – 2 hrs
  10. If procedure fails, institute alternative management plans

COPD Patients in Mercy University HospitalCOAD NIV Protocol

Please note - the above details relate to the Oxilog 3000 ventilator in CUH where the minimum delivered oxygen concentration is 40%.

In MUH, COAD (in contrast to LVF patients) can be non-invasively ventilated using the guidelines shown right.

Initiating NIV

Full ventilation reconsidered if:

  • Arterial pH<7.2
  • Arterial pH 7.2 - 7.25 on two occasions 1 hr apart
  • Hypercapnic coma (GCS<8 and PaCO2>8 kPa)
  • PaO2<6 kPa despite maximum tolerated FiO2
  • Cardiorespiratory arrest

Glasgow Coma Score

Score

Eye Opening

Verbal

Motor

6

Obeys commands

5

Speech orientated , localises to pain

4

Spontaneous eye opening

Confused speech

Withdrawal to pain

3

Eye open to speech

Incoherent words

Abnormal flexion to pain

2

Eyes open to pain

Only sounds

Extends to pain

1

No eye opening

No sounds

No movements

Treatment failure

  1. Is medical treatment optimal?
  2. Is Physiotherapy needed (particularly sputum retention)?
  3. What complications have developed (beware PTX or aspiration etc.)
  4. If PaCO2 remains high
    • To much O2? Maintain SpO2 between 85% to 90%
    • Excessive mask leakage?
    • Is circuit set up correctly?
    • Is patient synchronising with ventilator – adjust breathing rate and/or inspiratory and/or expiratory trigger
    • Is re-breathing occurring? - Check patency of expiratory valve (if fitted). Consider increasing EPAP
    • Is ventilation adequate – ?increase IPAP (increments of 2cm H2O to alleviate resp distress)
  5. If PaCO2 improves but PaO2 remains low
    1. Increase FiO2
    2. Consider increasing EPAP by increments of 2cm H2O. NB keep difference betw. IPAP and EPAP ≥ 6 cmH2O - so you may need to also increase IPAP.

Aims of NIV

  • Deal with acute phase of respiratory failure
  • Attempt to stabilise patient’s condition
  • Contact ITU registrar prior to transfer medical ward
  • Treatment failure warrants ITU admission

Infection control

  • Disposable masks and Exhalation ports should be disposed of
  • Headgear should be washed in a washing machine – be careful with the Velcro straps
  • Use a bacterial filter between the tube and the BiPaP machine to reduce contamination risk to machine

References

BTS GUIDELINE. Non-invasive ventilation in acute respiratory failure. Thorax 2002;57:192-211 © 2002 Thorax. Local PDF Copy.