Oxygenation

• Increase oxygenation by increasing:
  
  • FiO₂
  • peak end expiratory pressure (PEEP)
  • peak inspiratory pressure (PIP)
  • inspiratory time (T_insp)

CO₂

• Reduced by:

  • increased PIP

  • increased rate

  • occasionally by reducing excessive PEEP (beware of effect on oxygenation)

     

PIP

• Use lowest possible PIP to achieve visible chest expansion and adequate gas exchange on blood gas analysis

  • to minimise lung injury from barotrauma and inadvertent over-distension, avoid excessive PIP

  • need for higher pressures [e.g. mean airway pressure (MAP) >12 cm] could lead to consideration of high frequency oscillatory ventilation (HFOV) [see Ventilation: high frequency oscillatory ventilation (HFOV) guideline]

PEEP

• Use a PEEP ≥4 cm and increase incrementally up to 8 cm for improving oxygenation but when PEEP >6 cm necessary, take senior advice

T_insp

• Usually between 0.3–0.4 sec
• Avoid T_insp >0.5 sec except in term babies with parenchymal lung disease where a T_insp up to 1 sec may be used

Rate

• Fast-rate (≥60/min) ventilation is associated with fewer air leaks and less asynchrony compared to slow (20–40/min) rates

• If rate >70/min required, HFOV may be a more appropriate option [see Ventilation: high frequency oscillatory ventilation (HFOV) guideline]

Flow

• Flow 5–8 L/min is generally sufficient
• Consider higher flows at faster ventilatory rates or shorter inspiratory times 
• SLE ventilator has a fixed flow (5 L/min) that cannot be altered

Tidal volume (Vt)

• Target is 4–6 mL/kg
• Confirm that baby is receiving intended tidal volume before and after adjusting ventilation 

• Switch on humidifier and follow manufacturer’s recommended settings for optimum temperature and humidity

Setting 1

• When an admission of a preterm baby requiring ventilatory support (for recurrent apnoea, see Setting 2) 

  • rate 60/min

  • PIP 16–18 cm H₂O

  • PEEP 5 cm H₂O

  • T_insp 0.3–0.4 sec

  • FiO₂ as required

  • flow 6–8 L/min (not applicable to SLE)

• Adjust ventilatory settings depending on chest movement, SpO₂, and measured V_t

• Sample blood gas within 30 min of commencing ventilatory support

Setting 2

• For babies with normal lungs requiring supportive ventilation such as term babies with respiratory depression (asphyxia or drugs), babies with neuromuscular disorders or, in the post-operative period, and preterm babies with recurrent apnoea, set ventilator at following settings:
  
  • rate 40/min
  • PIP/PEEP 14–16/4 cm H₂O
  • T_insp 0.35–0.4 sec
  • FiO₂ as required (often 0.21–0.3)

Adjusting FiO₂

• Oxygen is a drug and should be prescribed as with other medications. This should be done by specifying intended target range of SpO₂ on baby’s drug chart
• Suggested target SpO₂ ranges (see Oxygen saturation targets guideline)
  
  • preterm babies: 91–95%
  • term babies: generally 96–100% but adjust according to the pathology (see Persistent pulmonary hypertension of the newborn and Congenital heart disease: duct-dependent lesions guidelines)

Target PCO₂

• Day 1–3: 4.5–8.5 kPa 
• Day 4 onwards: 4.5–10 kPa 
• If low PCO₂ wean ventilation without delay and recheck within 1 hr of low measurement

Altering ventilatory settings according to blood gases

If blood gases are outside the targets, first check the following:

• Reliability of blood gas: 
  
  • is the blood gas result reliable?  
  • has there been a sudden unexpected change from previous blood gas values? 
  • did sample contain an air bubble? 
  • was it obtained from a poorly perfused site?
• Baby’s status: 
  
  • is baby’s chest moving adequately? 
  • how is the air entry? 
• Ventilator and tubing
  
  • is there an air leak? [transilluminate to exclude (see Transillumination of the chest guideline) 
  • what is the V_t? 
  • are the measured ventilatory values markedly different to the set ones? 
  • is there a large (>40%) endotracheal tube (ETT) leak? 

• Small frequent changes are more appropriate than large infrequent ones

• While weaning baby off ventilator: 
  
  • reduce PIP (usually by 1–2 cm) until MAP 7–8 cm reached
  • thereafter, reduce rate to 20/min, usually in decrements of 5–10 breaths/min

Extubation

• Extubate babies <30 weeks’ gestation onto nasal CPAP or HFNC – for mode, (see Ventilation: Continuous positive airway pressure (CPAP)guideline or Ventilation: High-flow nasal cannulae (HFNC) guideline)
  
  • more mature babies with no significant chest recessions can be extubated directly into incubator oxygen

If baby in asynchrony with the ventilator (fighting)

• Ensure baby is not hypoxic or under-ventilated
• Exclude blocked ETT
• Look for obvious pain e.g. necrotising enterocolitis
• If possible, change to synchronised form of ventilation (VTV/HFOV/SIMV) 
• If sedation required, ensure it is adequate. Muscle relaxation seldom necessary and used only if IV morphine infusion (usually 10–20 microgram/kg/hr) already commenced

Ventilated babies to have:

• Continuous electronic monitoring of heart rate, ECG, respiratory rate, SpO₂ and temperature
• Transcutaneous monitoring can be useful in preterm babies on invasive ventilation who are clinically unstable. Discuss with consultant 
• Blood pressure
  
  • continuous measurement of arterial blood pressure in babies ≤28 weeks’ gestation, and those >28 weeks needing FiO₂ >0.6
  • cuff measurement 4-hrly in acute phase where arterial blood pressure not being measured
• ≥6-hrly blood gas (arterial or capillary) measurement during acute phase of disease
• Hourly measurement of colour, and measured ventilatory parameters. If sudden drop in V_t, check air entry
• Daily monitoring of intake, output and weight

Offer parents the following information, available from: bliss.org.uk/parents/in-hospital/about-neonatal-care/equipment-on-the-unit-1