Non-Invasive Ventilation: CPAP, BiPAP

High Flow Nasal Cannulae (HFNP)

• The prongs are larger to facilitate oxygen flow up to 60L/min
• Generates low levels of PEEP
• Can reduce tachypnoea and WOB
• Prevents CO2 rebreathing, therefore decreases PaCO2
• It is well tolerated
• Must be used with humidification

Comparison of Flow and FiO2

• Nasal cannula flow is 1-6 (L/min), FiO2 is 24-40%, comfort is Yes, mouth/nose breathing is Nose
• Facemask flow is 6-10, FiO2 is 35-60%, comfort is Mod, mouth/nose breathing is Mouth
• Venturi mask flow is 2-15, FiO2 is 24-50%, comfort is Mod, mouth/nose breathing is Mouth
• Non-rebreather flow is 10-15, FiO2 is 50-90%, comfort is No, mouth/nose breathing is Mouth
• High flow nasal cannula flow is 15-60, FiO2 is 30-100%, comfort is Mod, mouth/nose breathing is Nose

Ventilator Terminology

• FiO2 is the fraction of inspired oxygen, or O2 concentration 30-100%
• Respiratory Rate (RR) is the number of breaths per minute
• Tidal Volume (Vt) is the volume of gas moved into or out of the lung in a single normal inspiration and expiration
• Minute Volume (Ve) is the volume of gas moved in and out of the lungs in one minute. i.e. Vt x RR
• Positive End Expiratory Pressure (PEEP) or End expiratory positive airway pressure (EPAP) is the amount of pressure still in the lungs/alveoli at the end of expiration
• Pressure Support (PS) is the push of air to help a patient with spontaneous breath
• Peak inspiratory pressure (PIP) is the maximum amount of pressure during inspiration

Non-Invasive Ventilation (NIV)

• CPAP and BiPAP are 2 versions of NIV or non-invasive positive pressure ventilation (NPPV)
• Both CPAP and BiPAP require the patient to trigger breathing and to have a patent airway with adequate level of consciousness
• CPAP and BiPAP preserve the patient's ability to speak, swallow, cough and clear secretions and decreases risks associated with endotracheal intubation
• May have increased FiO2 or may just have pressure controls

Continuous Positive Airway Pressure (CPAP)

• Indications include ARDS, cardiac pulmonary oedema (HF), bilateral, diffuse pneumonia, Type 1 respiratory failure (PaO2<60mmHg), and OSA
• Benefits include Positive end expiratory pressure (PEEP)↓ WOB required on inspiration
• Facilitates alveoli recruitment, helps to shunt airways open and prevent collapse (atelectasis)
• Adds to respiratory reserve volume
• For heart failure patients, may improve cardiac performance by reductions to ventricular preload and left ventricular afterload which can help remove congestion Pulmonary oedema

BiPAP - Biphasic Positive Airway Pressure

• Uses two pressure levels: Inspiratory positive pressure airway pressure (IPAP) and Expiratory positive airway pressure (EPAP/PEEP)
• Indications include COPD, Type 2 (hypercapnic) respiratory failure (PaCO2 > 60mmHg), Obesity hypoventilation
• Shares the same benefits as CPAP as EPAP is still applied, with the added benefit of pressure support on inspiration, significantly decreasing the work of breathing required
• Aids in the avoidance of inspiratory muscle fatigue through the addition of inspiratory positive pressure, thus reducing dyspnoea
• Increases tidal volume which in turn increases the elimination of CO2 and reverses acidaemia

BiPAP / PS ventilation

• PEEP (EPAP) = 5cm H2O
• PS (IPAP) = 7cm H2
• Peak inspiratory pressure (PIP) = PEEP + IPAP
• 5 + 7 = 12cmH2O

Nursing Monitoring Requirements

• Patient education, outlining benefits/rationale for intervention
• Ensuring the mask fits the face and provides a good seal & monitor for presence of air leaks
• Complete Full MEWS and NIV observations are completed on both the NIV and MEWS charts
• Record half hourly for the first four hours, then hourly for the first 24 hours
• Patient monitored for respiratory and haemodynamic stability (Oxygen saturation + cardiovascular observations)
• Flow rate of supplemental oxygen if required
• Monitor NIV settings
• Note Time on and time off machine
• Pay attention to Patient comfort (Claustrophobia leading to agitation) and accessory muscle use
• Monitor Coordination of respiratory effort with the ventilator
• Keep a Fluid balance chart
• Assess Skin integrity, checking all pressure points, i.e. bridge of nose, tips of ears
• Ensure all equipment used on the patient is cleaned in the correct manner as per the manufactures instructions
• Watch out for Nasal congestion or nasal dryness

Invasive Ventilation - Intubated Patients

• Synchronised intermittent mandatory ventilation and Pressure regulated volume control (SIMV-PRVC)
• Set: RR, FiO2, PEEP, Vt, PS + other settings
• Synchronised with patients own intrinsic breathing
• Patient triggered breath
• Pressure supported – same as biPAP
• Mandatory ventilation only when required if patient doesn't initiate breath
• Volume control controls volume of mandatory breaths only
• Pressure regulated - pressure is regulated to prevent barotrauma and usually set to 35cm H2O as an alarm to warn if pressure is high and will cut off a breath if the pressure is too high (usually 40cmH2O)
• Pressure support ventilation (PSV) is a Weaning mode
• Set: FiO2, PEEP, PS
• No RR is set, the patient must trigger every breath
• Ventilator delivers a pressure boost to patient own breath
• Exactly the same as BiPAP only not via a mask is via a ETT or trachy

Nursing Monitoring Requirements

• Assessing and maintaining airway: an ETT or Tracheostomy
• Having Suctioning equipment
• Always have emergency adjunctive airways and BVM at bedside
• Checking the circuit is Humidified
• Monitoring Ventilator settings and alarms
• Ensuring Coordination of respiratory effort with the ventilator
• Ability to Monitor waveforms and capnography
• Patient monitored for respiratory and haemodynamic stability (Oxygen saturation + cardiovascular observations)
• Check Skin integrity, checking all pressure points: i.e. ETT in mouth a lips and tapes around face/neck etc

Explore key concepts of CPAP and BiPAP including pressure settings, patient monitoring, and comparing the benefits of CPAP, BiPAP and HFNC. Learn about initial nursing interventions, skin integrity monitoring, and ventilator adjustments.