Canberra Hospital and Health Services Clinical



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Suggested initial maximum frequency setting

Alert

Medical Officer to be present at bedside when HFOV commences. Amplitude needs to be adjusted by observing the baby’s chest until there is an adequate wiggle. If SaO2 poor/does not improve recruitment to be done by senior medical officer.




  1. Conventional ventilator circuit may be used or attach non-disposable HFO circuit

  2. Attach an in-line suction catheter to the circuit

  3. Open suction may be used in circumstances where secretions are causing tube blockage and cannot be removed with in-line suction.


OXYGENATION

The oxygenation can be increased by:

  • Increasing MAP to recruit the alveoli-this has the most profound effect on oxygenation

  • Optimum MAP corresponds to an AP chest film showing 8-9 posterior ribs

  • Increasing Fi02

For ongoing hypoxia consider



  • Displaced tube

  • Obstructed tube

  • Pneumothorax

  • Equipment failure (DOPE test)

  • Urgent chest x-ray-alter MAP based on over distension or under distension


CO2 ELIMINATION

The CO2 can be reduced by:

For ongoing hypercarbia consider



  • DOPE test as above

  • Increased airway resistance (MAS, BPD) or non-homogenous lung disease-is HFOV appropriate?

  • Chest X-ray

  • Under-inflated lungs indicate amplitude being delivered on non-compliant part of the pressure volume curve ie. point A in Figure 2

  • Over-inflated lungs indicate amplitude being delivered on non-compliant part of the pressure volume curve ie. point C in Figure 2

  • If all of the above seem ok try reducing oscillator frequency (discuss with consultant on call before changing frequency); lung impedance and airway resistance fail, leading to increased Vt



  1. Persisting acidosis/hypotension: Consider

  • Over distension

  • Reduce MAP: does oxygenation improve?

  • Consider chest X-ray


Outcome

  • The HFOV mode has been set correctly on the Leoni ventilator

  • The Ventilator is delivering the prescribed ventilation settings


Equipment and Set-up

  • Getinge SERVO-n ventilator

  • Grey set up tubing (from storage box on ventilator)

  • Fisher Paykel RT266 ventilator tubing

  • MR850 humidifier base with grey wires

  • Sterile water bag

  • Edi catheter:

  1. 6FR-49 cm, weight 0.5-1kg, length<55cm

  2. 6FR-50cm, weight 1-2kg, length<55cm

  3. 8FR-50cm, weight 1-2kg, length<55cm

  4. 8FR-100cm, weight >2kg, length 45-85cm


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Section 10 - Neurally Adjusted Ventilatory Assist (NAVA) in Neonates


Background


Neurally Adjusted Ventilatory Assist (NAVA) is a mode of mechanical ventilation intended for use in spontaneously breathing patients. It delivers ventilation in synchrony with and in proportion to the infant’s efforts. The patient's own electrical diaphragmatic activity (Edi) waveform is used to trigger-on and cycle-off each assisted breath. The pressure delivered depends on the size of the Edi signal, thus providing well synchronized proportional assist ventilation. The Edi waveform is recorded with an “Edi catheter”, a standard-sized naso- or orogastric feeding tube with miniaturized sensors embedded within. When correctly placed at the level of the gastroesophageal junction, the Edi signals are detected from the crural portion of the diaphragm.

Alerts


This section applies for non-invasive NAVA (NIV-NAVA) only.

Contraindications for using NAVA are:



  • MRI scanning: Edi catheter must be removed before MRI scanning

  • Congenital Anomaly: oesophageal atresia, diaphragmatic hernia

  • Weak diaphragm: Phrenic nerve injury, congenital myopathy

  • Insufficient/absent respiratory effort: brain anomaly, medication


Indication for NAVA

In the NICU the Getinge SERVO-n NAVA ventilator (refer to equipment section 2) is used as a non-invasive mode of ventilation for the following:



  1. Post-extubation as a weaning mode from invasive ventilation

  2. As an escalation mode from nasal CPAP to avoid intubation

  3. Alternative to nasal IPPV to treat apnoea


Equipment and Set-up

  • Getinge SERVO-n ventilator

  • Grey set up tubing (from storage box on ventilator)

  • Fisher Paykel RT266 ventilator tubing

  • MR850 humidifier base with grey wires

  • Sterile water bag

  • Edi catheter:

  1. 6FR-49 cm, weight 0.5-1kg, length<55cm

  2. 6FR-50cm, weight 1-2kg, length<55cm

  3. 8FR-50cm, weight 1-2kg, length<55cm

  4. 8FR-100cm, weight >2kg, length 45-85cm




Notes

  • The Edi catheter can be difficult to aspirate but placement can be reliably ascertained when Edi monitoring is commenced

  • Once a circuit is wet, it must be used on a patient within 24 hours

  • The expiratory block needs to be changed and sent to pre-rinse after use

  • The patient circuit check can only be reliably completed on a wet circuit, so should be performed immediately prior to use. All other pre-use checks can, however, be completed beforehand

  • Catheter should be changed every 7 days with ventilator circuit




  1. Collect all accessories on a clean trolley

  2. Assess correct Edi catheter size for patient and measure length from nose/mouth to ear to xiphisternum (nose- first preference to avoid movement of the catheter)

  3. Wet Edi catheter using sterile water. Pass and secure as you would a nasogastric (NG) or orogastric (OG) tube

  4. Connect ventilator to oxygen and air wall supply

  5. Plug ventilator power cord into blue UPS power point

  6. Insert humidifier base power cord to wall power supply

  7. Ensure expiratory block is in situ as per picture 1. This is sent to pre-rinse for sterilization between patients. There are 2 patient expiratory blocks. The spare block is kept with the other expiratory blocks in the clean utility room, in the cupboard above the bench

  8. Attach humidifier chamber to base and water bag to humidifier. Turn on humidifier base to commence warming

  9. Attach blue gas inspiratory tubing to gas inlet port and the other end to the humidifier as per picture 2 and 3. Attach white expiratory tubing to the expiratory block as per picture 2.

  10. Attach second blue tubing to the second humidifier post as per picture 3










Picture 1

Picture 2

Picture 3




  1. Attach Bubble CPAP patient interface to ventilator circuit (70mm or 100mm)

  2. No flow sensor is required

  3. Perform Edi cable test prior to commencing ventilation

  4. Ensure Edi catheter is attached to Edi cable on the ventilator

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