Breathing - NIV (bilevel)

Indications

Type 2 respiratory failure (pH <7.35 + PaCO2 >45mmHg)

COPD (after medical therapy and controlled oxygen)

Asthma (severe or life-threatening, maximum EPAP 5cm water)

Obesity hypoventilation with acute respiratory illness

Neuromuscular disease

Cystic fibrosis

Severe respiratory failure requiring intubation

Peri-intubation oxygenation

Ventilation during apnoeic period after induction

Contraindications (absolute in bold)

The presence of relative contraindications necessitates a higher level of supervision and early appraisal of whether to progress to intubation and invasive mechanical ventilation.

Airway

Facial and airway burns or haemorrhage

Fixed upper airway obstruction (unless directly prior to intubation)

Reduced ability to protect airway (GCS <8, copious secretions)

Breathing

Apnoea (unless directly prior to intubation)

Aerosolisation of high-risk microbes

Pneumothorax (without chest drain)

Circulation

Severe acidosis pH <7.15 (or pH <7.25 with additional adverse features)

Haemodynamic compromise

Disability

Confusion or agitation

Cognitive impairment

Alternatives

Face mask or nasal prong oxygen

High flow humidified nasal prong oxygen

Non-invasive ventilation (CPAP)

Intubation and mechanical ventilation

Informed consent

Medical emergency

Consent is not required if the patient lacks capacity or is unable to consent

Brief verbal discussion is recommended if the situation allows

or

Verbal consent

Less complex non-emergency procedure with low risk of complications

Potential complications

Aspiration

Pneumothorax

Mucus plugging

Gastric insufflation

Hypotension

Facial pressure areas

Discomfort

Claustrophobia

Procedural hygiene

Standard precautions

PPE: non-sterile gloves, surgical mask, eye protection, gown

Area

Resuscitation bay

Staff

Trained clinician and additional nurse (one on one monitoring if unstable)

Equipment

Appropriately sized Interface (full face or oronasal mask preferred)

Ventilator and circuit

Humidifier module

Positioning

Patient upright avoiding neck flexion

Medication

Morphine 2.5-5mg IV (symptomatic relief of agitation and distress)

Midazolam 0.5-2mg IV (symptomatic relief of agitation and distress)

Sequence (BiPAP setup)

Chest radiography or POCUS to exclude pneumothorax (do not delay initiation if not available)

EPAP: 5cm water, titrated to 1cm water per 10 kg estimated body weight (maximum 10cm water)

Place mask ensuring adequate seal

IPAP: EPAP + 5cm water, titrated to achieve 6ml/kg TV (maximum 20cm water)

Assist control mode (spontaneously triggered with patient’s respiration with backup rate)

Backup rate 20, with inspiratory time 1 second (I:E ratio 1:3)

Oxygen to achieve saturations 88-92%

Document plan for improvement or deterioration in next hour

Sequence (trouble shooting worsening pH, respiratory rate or patient distress)

Improve mask fit and seal

Sit upright without excessive neck flexion

Treat precipitant (e.g. bronchospasm)

Exclude pneumothorax (POCUS)

Exclude dynamic hyperinflation (confirm plateaus/inspiratory hold pressure = IPAP)

Low saturations (increase EPAP then increase oxygen to maintain stats 88-92%)

Tidal volume less than 6mg/kg or pCO2 rising (increase IPAP or lengthen inspiration time)

Patient not triggering machine (increase EPAP, lower trigger)

Patient inappropriately triggering machine (raise trigger)

Patient still distressed/asynchronous (adjust ‘ramp/rise’ of inspired breath, consider sedation)

Failing all the above, consider intubation or de-escalation (CPAP, HFNP, Hudson mask, palliation)

Post-procedure care

Continuous monitoring with regular assessment of patient comfort and respiratory effort

ABG with repeat after one hour and one hour after subsequent change in settings (arterial line suggested)

Document settings, tidal volume, saturation targets, escalation and failure plan

Tips

Maximum EPAP in asthma should not exceed 5cm water (risk of worsening intrinsic PEEP causing hyperinflation)

Evidence shows inadequate IPAP is often used in NIV for type 2 respiratory failure

Setting terminology varies between different brands of NIV

Discussion

There is a convincing evidence base for BPAP in type 2 respiratory failure caused by chronic obstructive pulmonary disease. In acute asthma it is reasonable to trial of NIV while maximal medical therapy is initiated, with BPAP preferred to CPAP. There is evidence in asthma for improved airflow with improvement in respiratory rate and dyspnoea influenced by the amount of pressure support above EPAP, hence BPAP is preferred to CPAP.

Recent studies of ePEEP in asthma demonstrate physiological benefits without significant increases in lung volume or dynamic hyperinflation. We suggest setting PEEP at 60-80% of auto-PEEP (estimated as 5cm H20). Further study is required, and the clinician should always consider dynamic hyperinflation as a likely cause of deterioration in the ventilated asthma patient.

Peer review

This guideline has been reviewed and approved by the following expert groups:

Emergency Care Institute

Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.

References

Davidson AC, Banham S, Elliott M, et al. BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults [published correction appears in Thorax. 2017 Jun;72 (6):588]. Thorax. 2016;71 Suppl 2:ii1-ii35. doi:10.1136/thoraxjnl-2015-208209

Davies M, Allen M, Bentley A, et al. British Thoracic Society Quality Standards for acute non-invasive ventilation in adults. BMJ Open Respir Res. 2018;5(1):e000283. Published 2018 Apr 5. doi:10.1136/bmjresp-2018-000283

British Thoracic Society Standards of Care Committee. Non-invasive ventilation in acute respiratory failure. Thorax. 2002;57(3):192-211. doi:10.1136/thorax.57.3.192

NSW Agency for Clinical Innovation. Non-invasive ventilation guidelines for adult patients with acute respiratory failure. Sydney: ACI; 2014. 38pp. Available from: https://www.aci.health.nsw.gov.au/networks/icnsw/intensive-care-manual/statewide-guidelines/non-invasive-ventilation-guidelines

NSW Agency for Clinical Innovation. Non-invasive ventilation device settings: a brief guide. Sydney: Aci; 2013. Report No. ACI/D13/1745

Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges' clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.

Dunn RJ, Borland M, O’Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.

Pallin M, Naughton MT. Noninvasive ventilation in acute asthma. J Crit Care. 2014;29(4):586-593. doi:10.1016/j.jcrc.2014.03.011

Stather DR, Stewart TE. Clinical review: Mechanical ventilation in severe asthma. Crit Care. 2005;9(6):581-587. doi:10.1186/cc3733

Sagana R, Hyzy RC. Positive end-expiratory pressure (PEEP). 2020 Jan. In UpToDate Available from: https://www.uptodate.com/contents/positive-end-expiratory-pressure-peep

© Agency for Clinical Innovation 2021

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