Non-invasive Ventilation

Question 1

Types of NIV?

Answer 1

Types

• BiPaP (Bilevel positive airway pressure)
• CPAP (continuous positive airway pressure).

Question 2

What is BiPaP?

Indications of BiPaP?

Contraindications of BiPaP?

What are the pressure targets? What do you have to do when you change pressure?

Answer 2

• Bilevel positive airway pressure involves a cycle of high and lower pressure to mimic the pressure changes during inspiration and expiration.

Indication

• Type 2 respiratory failure, typically due to COPD. The criteria for BiPaP is:
• respiratory acidosis (pH <7.35, PaCO2 > 6kPa) despite adequate medical intervention.

Main contraindication
- Untreated pneumothorax - if patient is known to have a pneumothorax, its preferable to place a chest drain before staring NIV

Other contraindications include structural abnormality/pathology in the face, airway or GIT

• if patient is at risk of vomiting, should not do NIV as it may lead to aspiration
• If patient is producing excessive amounts of respiratory secretions that they cannot clear away effectively, then should not do NIV.
• If patient has low GCS or is confused or agitated, then NIV is inappropriate.
• If patient has recently undergone upper GI surgery, positive pressure may put the anastomosis at risk.

Pressure targets

• Inspiratory positive airway pressure: 16-20cm H20
• Expiratory positive airway pressure: 4-6cm H20

IPAP should be increased 2-5cm every time until respiratory acidosis is resolved. Repeat ABG 1 hour after pressure change and 4 hours after, until acidosis is resolved.

Question 3

What is CPAP?

Indication for CPAP?

Answer 3

Continuous positive airway pressure - carried out in patients whose airways are prone to collapse.

Indications

• Obstructive sleep apnea
• Congestive heart failure
• Acute pulmonary oedema