Mechanical Ventilator and HFNC

Question 1

What is high-flow nasal cannula?

Answer 1

• Involves delivering oxygen at high flow (up to 6L/min)
• Heated and humidified
• For px who can breathe simultaneously

Question 2

What is the criteria for HFNC?

Answer 2

1) Hypoxemic respiratory failure

2) Following extubation

3) Postop in high risk and/or obese px following cardiac or thoracic surgery

4) Peri-intubation period

Question 3

What are the contraindications for HFNC?

Answer 3

• Nasal fracture, tumor or surgery
• Nasal congestion w/ tenacious secretions
• Basal skull fracture

Question 4

What are the physiological benefits of HFNC?

Answer 4

1) Decreased nasal resistance & Dead space
- HFNC creates a positive inspiratory pressure within the nasopharyngeal area (which has dead space where CO2 accumulates)
- ^ inspiratory pressure helps to “wash out” the OC2

2) ^ tidal volume and end expiratory volume

3) Increased secretion clearance
- relief of symptoms

4) Decreased bronchoconstriction

5) Recruitment at atelectatic lung regions
- Allows alveoli to open up for gas exchange

Question 5

What is the nursing management for px on HFNC?

Answer 5

• Vital signs (SpO2)
• Titrate O2 conc. and flow rate according to Dr and px presentation
• Look out for respiratory distress
• Look out for epistaxis, pressure areas, gastric distension and blocked nasal cannula
• Check sterile water bag is placed at the correct height for the humidifier and is not dry
• Check FiO2 and flow rate
• Ensure air blender is delivering the oxygen
• Turn on heater

Question 6

How to predict the risk for intubation after HFNC?

Answer 6

• ROX index
  ~ (SpO2/FiO2)/RR
  ~ High risk <3.85 , Low risk >4.88

Question 7

What are the complications of HFNC?

Answer 7

• Pneumothorax
• Pressure injuries
• Mask leak
• Oral dryness
• Gastric distention
• Vomiting
• Hypotension

Question 8

IMPT
What is the purpose of a mechanical ventilator?

Answer 8

• Allow oxygen to be delivered and CO2 to be removed (gas exchange)
• Reduce work of breathing for px w impaired lung function
• Provide respiratory support for px w apnoea or respiratory failure
• Protect airway and perform suctioning for px who are unable to remove their own secretions
• Provide ventilation for px under GA
• Minimise work of the myocardium
• Restore normal acid/base volume
• Increase lung volume
• Reduce atelectasis

Question 9

IMPT
What are the indications for a mechanical ventilator?

Answer 9

• Inadequate ventilation to maintain pH
• Inadequate oxygenation
• Excessive breathing workload
• Congestive cardiac failure
• Circulatory shock
• Severe neurological dysfunction
• Post-operatively

Question 10

What are the ventilator modes?

Answer 10

Assist control mode:
- For px with spontaneous breathing but have weak muscles
~ Myasthenia gravis, GGBS, ARDS
1) Continuous Mandatory Mode
- Tidal vol. given by MV
- Breaths initiated by MV if px does not do it spontaneously (set number of breaths)

2) Pressure Control Ventilation (PCV)
- Breath deliver is at a predetermined pressure depending on lung resistance
~ Volume is not constant
- Mandatory/set breaths or coupled with spontaneous breaths

Weaning Mode:
- When preparing to wean off MV
1) Synchronised Intermittent Mandatory Ventilation (SIMV)
- Mandatory and spontaneous breaths
- Pressure support to reduce work of breathing
- “sometimes MV sometimes px)

2) Pressure Support (PS)
- All breaths by px
- Only pressure support with variable tidal volulme

3) Continuous Positive Airway Pressure (CPAP)
- Delivers a constant pressure to prevent airway collapse during exhalation
- All breaths by px
- Usually for COPD or apnea

Question 11

What are the ventilator settings?

Answer 11

1) Tidal volume
- Vol of gas delivered per ventilator breath

2) Oxygen concentration (FiO2)
- Between 21% - 100%

3) Positive end expiratory pressure (PEEP)
- Positive pressured delivered at the end of expiration of ventilator breath

4) Inspiratory:Expiratory ratio
- Length of each

5) Sensitivity
- Pressure trigger
- Flow trigger

Question 12

What are some potential complication of MV?

Answer 12

• Barotrauma
  
  • Injury caused by a change in air pressure, affecting typically the ear or the lung
• Volume trauma (extensive vol. in alveoli)
• Atelact trauma (due to shearing from repeated opening and closing)
• Pneumothorax
• Subcutaneous emphysema
• Impact venous return due to ^ positive pressure

Question 13

What is the nursing management for MV?

Answer 13

• External length of ETT, lip marking and cuff pressure
• Secure ETT and keep suctioning apparatus at beside
• Auscultation of both lungs, symmetrical
• Ensure NGT is inserted and the placement is confirmed with ETT and CXR
• Ensure px is sedated to avoid px-ventilator dyssynchrony
• Continuous monitoring
  ~ MAP, BP, HR, SpO2, temp
  ~ ECG
  ~ ABG
  ~ Sedation score (oversedation makes it hard to initiate own breathing but undersedation may cause agitation and restlessness)
• Troubleshoot alarm triggers
  ~ High pressure (due to accumulation of secretions)
  ~ Low pressure (loose connection of ventilator tubings)
• 5 element VAP bundle
  1) Head of bead elevation
  2) Oral care with chlorhexidine
  3) Stress ulcer prophylaxis
• eg PPI
  4) Daily sedation assessment and spontaneous breathing trials (to wean px off)
  5) Deep venous thrombosis prophylaxis
• Maintain humidification of ventilated gas for px with with Heat Moisture Exchanger (HME)
• ETT suctioning
• Prevent PU formation