Critically evaluate the role of non-invasive ventilation (NIV) in critically ill patients.
Answer and interpretation
NIV provides ventilatory support for patients with respiratory failure via a sealed face-mask, nasal mask, mouthpiece, full face visor or helmet without the need for intubation. Ventilatory support may be with CPAP or bi-level modes and delivered by a range of ventilators from specifically designed devices to full-service ICU ventilators.
NIV decreases resource utilisation compared with invasive ventilation and avoids the associated complications.
Patient selection and a well-designed clinical protocol are important to avoid delaying intubation in patients who are not suitable for and/or failing NIV.
- APO – alveolar recruitment, decreased afterload, decreased work of breathing
- COPD – decrease work of breathing and unload respiratory muscles Immunosuppressed
- Planned strategy post extubation in selected patients
- OSA / Obesity hypoventilation syndrome
- Patients with not for intubation/ treatment limitation orders who may qualify for HDU admission or admission to respiratory care units
- Post-operative patients – in selected patients
- Rib fractures
- Cystic fibrosis as bridge to transplantation
Evidence for its use:
- APO – studies show decreased intubation rate and faster time to resolution of respiratory failure and reduction in mortality and hospital length of stay
- COPD – RCTs and Cochrane review (14 RCTs) showed significant improvement in intubation rates, complications, length of hospital stay and mortality rates for NIV compared with invasive ventilation
- Immunocompromised – – 2 studies, one looking at solid organ transplant recipients and one looking at patients with haematological malignancy showed benefit with NIV, i.e. fewer intubations, complications and reduced ICU and hospital mortality
- Asthma – probably beneficial but limited evidence
- Rib fractures – fewer episodes of pneumonia but no mortality benefit and limited evidence
Evidence against its use:
- Use as rescue strategy for failed extubation – delays time to re-intubation. May be of benefit as part of weaning strategy and planned intervention post extubation especially in COPD patients
- ARDS – not recommended as first line therapy
Predictors of success
- Younger age
- Unimpaired conscious state
- Moderate rather than severe hypercarbia
- Rapid improvement in physiological parameters
- Cardiac / respiratory arrest
- Cardiac instability – shock, ventricular dysrhythmias, severe acute myocardial ischaemia GI bleeding
- Intractable vomiting
- Inability to protect airway – poor cough, excessive secretions, decreased conscious state Upper airway obstruction
- Following upper GI surgery (some debate about this)
- Facial and nasal trauma and pressure sores
- Gastric distension
- Dry mucous membranes
- Aspiration of gastric contents
- Invasive ventilation
- HFNP – may provide CPAP 5mm Hg
Summary statement / My Practice
Role of NIV in critically ill includes APO and respiratory failure in COPD and immunosuppressed patients. In my practice I use NIV as a planned strategy post-extubation in selected patients and as ventilatory support for patients with respiratory failure and treatment directives limiting care. I do allow its use to delay or withhold intubation in those who need this.
- Pass rate: 60%
- Highest mark: 8.5
Examiner’s additional comments:
- NIV is a fundamental part of intensive care practice and the overall level of understanding was poor. Few candidates were able to demonstrate detailed knowledge of this core therapy.
- Candidates were not expected to include as much detail to score good marks. Essential points included indications, some mention of evidence for and against, contra-indications and complications. Candidates were given credit if they included valid points not in the answer template.