Initiating NAVA
Initiating NAVA
In NAVA Pressure Support, the patient will control tidal volume and respiratory pattern.
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Initially set the NAVA level to 1. Allow the signal to stabilize over several breaths.
The Edi should be approx 10 uV +/- 5 uV
A typical NAVA level would be 05 - 3.0
Transitioning from monitoring EDI to using the neural signal to trigger the synchronised pressure support.
Patients will find the NAVA generally comfortable and well tolerated. In general transitioning to NAVA is usually simple and straightforward. All breathing efforts are responded to and promptly supported with less asynchrony. There may also be less lung and diaphragmatic injury than with other support modes. The mode may reduce the risk of over- and under- assist from the ventilator.
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They may require less sedation and may have improved sleep. The UK NAVA trial seeks to try and establish whether the theoretical or observed advantages of neural monitoring or NAVA pressure support, translate to improved patient outcomes eg less time on a ventilator; increased chance of survival and accelerated rehabilitatio/reduced sequelae from supportive intensive care. The hypothesis is that the combination of neural monitoring with the option for NAVA pressure support will translate to these improved outcomes.
Patient with ARDS - ventilating in pressure control. The ECG positioning tool was used to indicate the nasogastric tube needed to be advanced. Then NAVA was established and neural drive increased as respiratory load being delivered by ventilator was reduced. Very easy transition: no issues reported by bedside nurses.
Patient with ARDS - recruited in APRV and then transitioned to NAVA. Very easy transition - no issues reported by bedside nurses.
Patient with cardiac failure and muscle weakness, had low neural drive when Edi catheter placed. The low neural drive signal gave an unreliable location. Occasional ECG strikes could be seen indicating catheter not actually in far enough. Advanced 5 cm from 65cm to 70cm and neural drive became immediately clear. The patient was then placed in NAVA without difficulty-the initial NAVA level was set against the existing pressure-support breath. This highlighted the importance of considering neural catheter position if drive appears flat. It also highlighted that if the neural drive signal is flat, occasional pink strikes on ECG positioning tool, may be unreliable, perhaps originating from background.
Patient with recovering ARDS and barotrauma (pneumothorax), delirium and ongoing sepsis. High spontaneous ventilatory drive.
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Overlay and positioning tool reviewed to demonstrate potential benefits of NAVA (improved synchrony) and how to determine the starting level of NAVA gain (in this case 1). When the NAVA level went below this the Edi rose steeply. Above a NAVA gain of 1.5 there were no advantages. The main issue appeared to be a high central ventilatory drive. NAVA appeared to provide a better spontaneous support mode than conventional pressure support. Transition from pressure support was reported to be uneventful and well tolerated by the patient. NAVA was assessed as being at least as effective as pressure support in this patient.
Patient with tracheostomy and speaking valve-he found it more comfortable to use the speaking valve in NAVA than when in pressure support. Despite a spinal cord injury at C5-6 he was generally significantly more comfortable in NAVa than pressure support.