NAVA
About
- Patient-initiated synchronized breathing mode
- Breathing support is triggered by the electrical activity of the diaphragm (Edi)
- Patient controls the respiratory rate, inspiratory time, and the tidal volume with assist from the ventilator
- Operator sets the NAVA level (support). The higher the NAVA level, the lower the EDIpeak which corresponds to less work of breathing(WOB).
- NAVA level is multiplied by the measured Edi signal to provide a pressure which is proportional and synchronized to the patient’s effort
- NAVA ventilation delivers ventilatory assist in proportion and synchronized to the patient’s Edi (the electrical activity of the diaphragm)
- NOT MRI compatible
How it works
- Can replace your OG/NG tubes
- Has 10 electrodes, 9 of which are used to read the electrical activity of the diaphragm
- Catheter is placed either nasally or orally, until the diaphragm is in the middle of the 9 electrodes
- Edi MIN
- Tonic activity of the diaphragm (continuous tension of muscles at rest) − Normal target 1-4 mcV
- Edi Peak
- neural inspiratory effort (how hard diaphragm is working to receive the tidal volume (vt) the patient wants) − Normal 5-15 mcV
- Edi Trigger
- Difference in Edi mcV needed to be above previous Edi MIN to trigger the next breath, usually 0.5
- NAVA level
- A multiplier of the patients EDIpeak to control the level of work the patient must perform to reach the vt he/she wants.
- Support that the patient gets to create Peak Pressure is calculated from PIP = NAVA Level x Edi (Peak – Min) + PEEP. This is done multiple times throughout the inspiratory phase and not just at the start of a breath.
Benefits
- Better patient synchrony with the ventilator
- Lower PIP and O2 needs
- Better sleep quality
- Brain knows what the body wants at all times
- Lung protective
- Decreased risk for barotrauma and volutrauma
- Less sedation is needed and patient might be comfortable
- Assess proper PEEP levels via Edi min
- Diaphragm atrophy/dysfunction is reduced
- Better able to assess patients WOB post-extubation
Requirements for Patient Use
- Spontaneously breathing
- Must have a working signal to the diaphragm
- At least one side with intact phrenic nerve
Contraindications
- Patients with an absent electrical signal from brain to diaphragm
- Patients with paralysis/neuromuscular blockade
- Esophageal bleeding
- Inability to place an NG/OG tube
- Actively used cardiac pacemaker- depends on the patient
Catheter Placement
- Do not use any lubricants to place, only sterile water
- Monitor catheter placement, by observing QRS waveforms on the ventilator
- As catheter goes from above the diaphragm to below, QRS waveforms will dampen
- As middle of the catheter gets closer to diaphragm, the QRS will turn Blue with a correlating Edi signal
- Middle 2 waveforms should be Blue QRS
- QRS complex is large on top waveform, small on bottom
- Look for disappearing P waves from the top to the bottom waveforms
NAVA Orders
The orders that need to be entered by the doctor for NAVA patients include:
- Mode: NAVA
- PEEP
- NAVA level: Set either Edimax target range (5-15 microvolts preferred) or as an absolute NAVA level. For example NAVA level of 2 cmH2O/microvolt and notify MD if Edimax is not in the 5-15 microvolt range.
- PS
NAVA Safety
- If the catheter falls out or became ineffective, and the patient is trying to breathe, the ventilator will default to Pressure Support mode and resume NAVA when working again
- Whatever trigger is noted first, will control what breath type is given. Ie: if the ventilator registers a flow trigger before a NAVA signal, then the PS setting will be given. This might occur with large leaks with the flow trigger set too sensitively.
- Backup PC/Rate, in-case the patient goes apneic, the ventilator will automatically kick in and ventilate the patient
Considerations:
- NIV NAVA can be used with any interface approved to deliver NIV.
- While NIV NAVA is triggered via the NAVA catheter, large leaks could still produce issues. If the leak is excessive, an excessive inspiratory flow alarm will occur even as the NIV triggers and cycles with the patient's effort.
- In the infant mode only, the low minute ventilation alarm can be turned off with an order, however only when the high minute ventilation is set at 1.0 or less.
- If nasal cannula prongs are used as the interface to the patient, expect higher pressure support readings due to the high airway resistance produced by the prongs. This could also occur with any pronged interface.
- The NAVA breath is terminated when the peak inspiratory pressure(pip) reaches 5 cmH2O below the high pressure alarm setting.