Neurally Adjusted Ventilatory Assist Jennifer Tronson VVC RSPT 233 10/10/2015

How Do We Inhale? Diaphragm drops Thoracic cavity expands Pressure drops Negative Pressure Gradient is formed from the mouth to the alveoli Air flows in and down the pressure gradient until equilibrium is reached

How Do Ventilators Know When a Patient Wants to Take a Breath? Diaphragm drops Thoracic cavity expands Pressure drops Negative Pressure Gradient is formed from the mouth to the alveoli Air begins to flow down the gradient The ventilator is triggered to deliver a breath by settings predetermined by the therapist or a measurement taken of previous breaths Or….

How Do Ventilators Know When a Patient Wants to Take a Breath? Water in the tube alters the pressure or flow Patient movement triggers a breath No breath is delivered because the patient is unable to alter flow or pressure enough to trigger the ventilator Even if everything works according to plan there is a significant delay between the patient’s brain deciding it should take a breath and the ventilator delivering the breath

How Does Our Body Know We Want to Take a Breath? The respiratory center responds to chemo and pressure receptors in the body and sends a signal through the phrenic nerve to the respiratory muscles to contract and expand the thoracic cavity.

Is There a Better Way? What if the ventilator could be triggered by the same signal that triggers the respiratory muscles? Increased patient synchrony Increased patient comfort Potentially lower levels of sedation What if that signal could also tell the ventilator how much support is needed for each breath? Support will be calculated based on the signal the brain sends to the diaphragm so there will not be a lack of support if the patient is requiring a deeper breathe nor too much support if the patient is trying to take a smaller breath.

NAVA - Synchrony Redefined

Triggering Comparison

NAVA Neurally Adjusted Utilizes a catheter to detect the electrical activity signaling in the diaphragm Edi Uses the strength of the Edi to determine how much assist to deliver to the patient Bases each breath on the electrical signal, not trending from previous breaths

NAVA Ventilatory Assist The signal from the Edi catheter is used to determine the amount of support supplied and when the support is supplied. The support is provided in the same fashion no matter the means of delivery to the patient (Invasive or Non-Invasive), and is unaffected by leaks as the breath is cycled on and off by neural signal not preset volume or pressure.

NAVA Ventilatory Assist The support is supplied in synchrony and proportion with the Edi signal The amplification applied to this support is the NAVA level NAVA level X (Edi signal-Edi min)+PEEP

Synchronized Ventilatory Assist

Background NAVA is a system that belongs to MAQUET It is compatible with the SERVO- I ventilator Has been available in the US since late 2007 The largest adopter of the technology in Southern California is Loma Linda, but it is also used in Kaiser, Children’s Hospital of Orange County, and newly in the Huntington Hospital

Background In the US it is primarily used in NICU/PICU, though in Europe it is widely used in adults. This is attributed to the obvious “ah-ha” moment that happens when you switch a baby over to NAVA and see them stop fighting the vent, relax and succeed on lower pressures and lower FiO2s Several factors have attributed to its slow adoption in adult markets in the US, Drs and therapists not wanting to relinquish control, learning curve, inertia…

Background

Setup - Select the appropriate Edi Catheter Edi catheter ‘s differ in iED making them uniquely suited to patients based on height. Only the 12 and 16 Fr sizes have a lumen for evacuation

Setup – Perform Edi Module Function Test Insert the Edi Module into the SERVO-I Connect the Edi Cable to the Edi Module Perform Edi Module Function Test

Setup – Position the Edi Catheter Measure NEX & Calculate Insertion Distance

Setup – Position the Edi Catheter Inspect the catheter Put the tip in sterile water – no other lubricant Allow the tip to remain in the water for 5 seconds before removing

Setup – Position the Edi Catheter Insert the catheter to the Y value determined earlier Connect the catheter to the Edi module

Setup – Verify the Catheter Position Once you verify that the 2 middle rows are highlighted in blue note the insertion depth and secure the catheter in place.

Setup – Monitor the Edi Signal Edi signal can be seen in all modes including standby Edi Peak and Min are available for each breath cycle Signal trending for 24 hours are available

Setup – Set the Initial NAVA Level Open the NAVA preview window with the Neural Access key Set the initial NAVA level to achieve the same or slightly lower pressure level that is currently being delivered to the patient Press the NAVA level key then use the rotary dial to adjust the level

Setup – Select and Set NAVA Mode Utilize the calculation to compare your pressure levels

Setup – Select and Set NAVA Mode Set PEEP Set FiO2 Set Trigger Edi This detects increases in Edi and should be set to filter out background noise so that it does not affect the patient’s ability to trigger a breath

Setup – Select and Set NAVA Mode Set Pressure Support above PEEP Must be set low enough to not induce hyperinflation and interfere with the Edi signal Set Backup Ventilation This is AC/PC mode that is utilized if the patient becomes unable to signal for a breath

Setup – Select Alarm Limits Set Alarms that are adequate for the patient and in line with your facilities alarm limit policies.

Set Up Video

Weaning Titrate NAVA level to obtain Edi Values that are 60% of the Edi max value during the SBT. Repeat at least once daily Extubate when SBT is successfully tolerated for 2 hours

Contraindications Any contraindications for naso-orogastric feeding tube such as upper airway surgery and skull base fractures NAVA would not be appropriate for a patient exhibiting an undesirable breathing pattern such as Biot’s breathing though the Edi information may remain a useful tool Known phrenic nerve lesions Severe hiatal hernia Need for MRIs as the Edi catheter is not approved for use in MRI environments NAVA may be contraindicated in a patient that is experiencing seizures or frequent panic attacks that alter the normal breathing patterns

Works Cited http://ww2.maquet.com/uk/product/NAVA?tab=Features http://www.ncbi.nlm.nih.gov/pubmed/22015130 http://rc.rcjournal.com/content/56/3/327.full http://www.respiratorytherapyfiles.net/uploads/2/6/3/1/26319264/servo_i.pdf http://www.researchgate.net/publication/41056512_Patient-ventilator_interaction_during_pressure_support_ventilation_and_neurally_adjusted_ventilatory_assist http://respiratory-care-sleep-medicine.advanceweb.com/Magazine/References/NAVA-Initial-Setup-Guide.aspx http://www.dicardiology.com/node/25122/3 http://www.criticalcarenews.com/upload/pdf/CCN_case26_MX-1030_CCN_case26_SERVOI_NAVA_Weaning_Adults_EN_NONUS.pdf http://www.criticalcarenews.com/CcnTrainingPage.aspx?area=1&ContentTypeId=16&TrainingID=29