Susan P Pilbeam, MS, RRT, FAARC

Clinical Applications Specialist

Maquet, Inc

Within the past 12 months, the presenter has had an affiliation with the Maquet, Inc who is sponsoring this presentation.

Objectives� Review the definition and the causes of patient-

ventilator asynchrony.

� Show the frequency that asynchrony occurs.

� Demonstrate how the electromyograph (EMG) of the diaphragm can be used to identify asynchrony and improve synchrony

� Discuss how an alternative method of ventilation can use the EMG of the diaphragm to reduce asynchrony.

� Demonstrate the use of Edi and NAVA.

What is Patient-Ventilator

Asynchrony?

�“…a mismatch between the patient and the ventilator inspiratory and expiratory times.” (Thille, Inten Care Med; 32, 1515, 2006)

What is the Most Commonly

Reported Form of Asynchrony?� “Wasted Effort” – The patient wants a breath and

doesn’t get one.

� The most severe form of asynchrony:

� A combination of oversensitivity trigger setting, high sedation levels and high assist levels.

� Leaks also contribute to asynchrony.

Sinderby C, Beck J: Neurally adjusted assist for infants in critical Condition. Pediatric Health 2009, 3(4):297-301 (edit)

Ventilator Waveform IdentificationGeorgopoulos (2006)

� “Flow, volume, and airway pressure waveforms are valuable real-time tools in identifying various aspects of patient-ventilator interaction.”

� However, “If you aren’t looking for something, you surely will not to find it.”

Can You Identify Asynchrony?

Experts Versus Non-Experts

Columbo, et al, CCM 2011, 39:11

Experts Versus Non-Experts

Columbo, et al, CCM 2011, 39:11

Experts Versus Non-Experts

Columbo, et al, CCM 2011, 39:11

Experts Versus Non-Experts

Columbo, et al, CCM 2011, 39:11

Experts Versus Non-Experts

Columbo, et al, CCM 2011, 39:11

Synchrony?

Courtesy: Dan Rowley

SAME PATIENT SHOWING DIAPHRAGM ACTIVITY

1 2 3

1 2 3

Courtesy: Dan Rowley

PRESSURE SUPPORT –

IS THE PATIENT TRIGGERING THE VENTILATOR?

YOU HAVE SEEN A PATIENT LIKE

THIS

John Marini, 1992, Resp Care

Patient-Ventilator Asynchrony� How much of asynchrony is “us”?

� How much is the machine?

How Do Ventilator Parameters We Set

Affect Patient-Ventilator Synchrony?

� Setting sensitivity appropriate to the patient

� Inappropriate trigger increases ventilation time. (deWit,

et al: CCM 2009, 37:2740)

� Providing adequate inspiratory flow

� Insuring appropriate volume or pressure delivery

� Ending the breath when the patient is done

How Often is Asynchrony Really Present?

� One in four patients (25%) exhibited asynchrony during assist/control or PSV ventilation. (Thille et al: Inten Care Med 2006:32:1515; De Wit, et al (CCM 37(10): 2009)

� Exhibited as inability to trigger or double triggering, or inappropriate Ti time.

� During SIMV 53% of the total mandatory breath time was asynchronous compared to the measured neural drive.

� Every mandatory breath was asynchronous � (Beck et al: Ped Research, 65(6), 2009, 663)

But…(With Heavy Sedation)…!

� Lack of use of the diaphragm and mechanical ventilation can also lead to wasting (severe atrophy) and damage to the respiratory muscles. (ventilator induced diaphragm dysfunction, VIDD)

� “Specifically related to the use of mechanical ventilation is the loss of diaphragmatic force generating capacity.” Levine, et al NEJM 2008, 358:13

� Increased length of intubation and ventilation (Petrof, et al Curr Opin Crit Care 16:19-25, 2010)

DISUSE ATROPHY IN NEONATES

Source: Knisely A.S., et al. Abnormalities of diaphragmatic muscle in Neonates with ventilated lungs. The Journal of Pediatrics. 1988; 113:1074-7

Long term ventilatory assistance may predispose diaphragmatic myofibers to disuse atrophy or failure of normal growth. (1988)

47 Days of mechanical ventilation

0 Days of mechanical ventilation

ATROPHY AND DAMAGED OF THE

DIAPHRAGM MUSCLE

� “The diaphragm is not a biologically inert organ that can be light-heartedly substituted by the ventilator:

the vital pump is both malleable and vulnerable.”Vassilakopoulos T et al. AJRCCM,2004;169: 336-341.

Ventilator Induced Diaphragm

Dysfunction (VIDD)� “…18 – 69 hours of complete diaphragmatic inactivity

and MV results in marked (50%) atrophy of human diaphragm fibers.” Levine et al. NEJM 2008; 358(13):1327-1335.

� Additional study of volunteers and a second group of organ donors.

� Ventilation between 2 and 4 hours and up to 10 days.

� Leads to diaphragm disuse degeneration. (Hussain SNA, et al, 2010, AJRCCM 182:1377)

PROBLEMS WITH MECHANICAL

VENTILATION

� Not only…

� Asynchrony

� Atrophy and ventilator induced

diaphragm dysfunction (VIDD)

� VILI (Baro/volume/biotrauma)

� VAP

PURPOSE OF VENTILATION?

� A major goal is to reduce a patient’s work of breathing, not increase it.

� Achievement of this goal is dependent on satisfactory patient-ventilator interaction.

� “The machine needs to cycle in unison with the rhythmic contractions of a patient’s diaphragm.”

Parthasarathy S, Jurbran A, Tobin MJ. Amer J of Crit Care Med 2000; 162:546-552

ACHIEVING SYNCHRONY

� Synchronous ventilation can potentially be achieved by:

� Manipulation of rate

� Inspiratory time

� Employment of patient triggered ventilation

� Largely achieved by the practitioner

Greenough A, Dimitriou G, Prendergast M, Milner AD. Synchronized mechanical ventilation for respiratory support in newborninfants. Cochrane Database of Systematic Reviews 2008, Issue 1. Art.No.:CD000456. DOI:

Respiratory Therapist

Have Hard Jobs� This seminar has presented important issues that are

a part of our job.

� Patients with asthma are another example of the serious problem we deal with.

Another Asynchrony Phenomena

Double Triggered Breath

� Double triggering is defined as two cycles of breath delivery separated by a very short expiratory time.

Not using ventilator graphics, but…

Identifying asynchrony using esophageal pressures and

the diaphragm’s electrical activity (Edi)

Thille & Brochard, Inten Care Med 2007; 33:744

Possible Causes Double Trigger

� Patients with ALI/ARDS and high ventilatory demand and low PaO2/FIO2 ratio, high Ppeak and high levels of

PEEP.

� In patients on PSV, set pressure too high for patient and

over-sedation can lead to double trigger.

BENEFITS OF SYNCHRONY

� During synchronized mechanical ventilation� Positive airway pressure and spontaneous inspiration

coincide.

� If synchronous ventilation is provided:� Adequate gas exchange

� Lower peak airway pressures

� Potentially reducing baro/volutrauma and, in infants, bronchopulmonary displasia (BPD)

Greenough A, Dimitriou G, Prendergast M, Milner AD. Synchronized mechanical ventilation for respiratory support in newborninfants. Cochrane Database of Systematic Reviews 2008, Issue 1. Art.No.:CD000456. DOI:

WHAT TO DO WHEN THE PATIENT

IS NOT SYNCHRONIZED?

� What is our current clinical practice when the patient is out of sync with the ventilator?

�Can you say…

PropofolPropofol

Problems With Sedation

�Already identified VIDD

�Increased length of intubation

�Increased length of stay

Sedation Trials

� Spontaneous awakening trials (SAT, interruption of sedation) paired with spontaneous breathing trials(SBT).

� Resulted in better outcomes than with standard approaches.� Improve ventilator free days 14+7 vs. 11+6 = 3+1 Day

� Decrease time in coma

� Decrease time in the ICU and Hospital

� Sedation trials (awakening trials) should become the standard approach.

Lancet 2008; 371: 126–34, Ely’s group

�An ECG is the standard of care for a variety of patient problems.

�What if we could monitor the ECG of the diaphragm?

ECG Waveforms

ECG OF THE DIAPHRAGM

� Monitoring diaphragmatic electrical activity permits monitoring between neural drive and the ventilator breath delivery.

� Monitoring diaphragmatic electrical activity comes closest to representing the ideal in ventilator monitoring.

Source: MacIntyre N. Evolving Approaches to assessing and monitoring patient ventilator interaction. Current Opinion in Critical Care. 2010 Published ahead of print.

How Edi is Monitored?

Nasogastric Tube with Monitoring

Electrodes� Similar to the leads on

an EKG

� Electrodes are internal (esophagus)

� Edi is 1/10th and 1/100th

the strength of the heart’s electrical activity.

Edi Catheter Position

Monitoring Available in Any Mode

USING EDI TO MONITOR THE DIAPHRAGM

AND IMPROVE SYNCHRONY

� What is a normal Edi signal?

� What causes a low Edi signal?

� What causes a high Edi signal?

Low Edi signal� Sedation

� Neural disorder

� Muscle relaxants

� Paralytics

� Brain injury or

� Brain dead

� Hyperventilation

High Edi Signal� Increased respiratory drive

� High CO2 values or low O2 values

� Increased resistance

� Increased respiratory

workload

� Sigh Breath

Assist/Control Volume

Using the Edi to Using the Edi to control the ventilatorcontrol the ventilator

PC Card

Edi Catheter

What is the Ideal Ventilator?

“Ideal ventilator should be able to record the activity of the respiratory neural system, and use that measurement to select a satisfactory tidal volume. “

Laghi, Franco, NAVA: Brain over Machine? Intensive Care Medicine; 2008

NAVA in a 1 day old 28 week infant with RDS

Patient Case – 54 y.o. Woman� Post-op for draining of an intracraneal bleed.

� Three days on ventilatory support with difficulty weaning.

� Patient became very agitated whenever sedation level was reduced (40 mg of propofol)

� Unknown cause of agitation

� ABG on current settings: 7.43/ PC02 38/ P02 281.

Ventilator Settings

Edi Catheter Inserted� No activity from the diaphragm

� Still receiving sedation

� Propofol was weaned

� NAVA was implemented as soon as Edi was restored. The patient was calm and not agitated!

� Vital signs stable

Patient on NAVA Mode

WITHIN 30 MINUTES, SUPPORT REDUCED

Patient Extubate – 1.5 Hours� Ventilator on Standby

� NAVA catheter staying in place

� Used to monitor patient after extubation

� The physician said that this patient would have been intubated at least a day or two longer.

Used Catheter to monitor patient after

extubation.

Patient Admitting Information� A women in her late 50s year was brought into the

Emergency Department by ambulance shortly after midnight.

� She had signs of respiratory failure.

� Blood gases were drawn on a non-rebreathing mask:

� Ph 7.11 PaCO2 = 56, PaO2 = 51 SpO2 60%

� Chest radiograph report: Ground glass pattern with left upper lobe opacity, possible the beginning of ARDS and extensive bilateral infiltrates.

Day 1 – 00:05 (After Midnight)

Mechanical Ventilation� The patient was intubated and placed on mechanical

ventilation.

� Aspiration of secretions from the ET tube showed the contents of a recently eaten meal.

� PRVC, Vt = 600 , rate =18 , PEEP = 7, 100% oxygen. (VE = 10.8 L/min)

� Blood gases: pH = 7.11, PaCO2 = 56, PaO2 = 51 SpO2 = 89%

� Physician stated this patient was in early ARDS: low compliance, poor PaO2/FiO2 ratio.

Day 1 Continued:

Protective Ventilation� Vt decreased to 500 ml (6 mL/kg IBW) and rate

increased to 20 b/min (VE = 10 L/min)

� Blood gases: pH = 7.20, PaCO2 = 50, PaO2 = 62, SpO2

= 90%.

� Physician stated this patient was in early ARDS: low compliance, poor PaO2/FiO2 ratio.

Difficulty Oxygenating the Patient� Same day adjustments to ventilator.

� PRVC: Vt = 350, rate = 22,

� PEEP = 14, oxygen at 100%

� pH = 7.31, PaCO2 = 37, PaO2 = 92 SpO2 = 98%

� Ventilation was improved, but oxygenation was not.

Day 2 – Not Much Change� With no significant improvement by the morning of

the next day, the RTs discussed the use of NAVA with the patient’s physician.

� NAVA was instituted the afternoon of the second day.

� During the night the RT reported the patient tolerated NAVA well without the need for excessive sedation.

� The RT stated that the patient was coughing so much that they had to change the expiratory filter 4 times during their shift. “You should have seen the stuff (secretions) coming out of her lungs.”

Day 3- Morning Chest Radiograph

RADIOLOGIST’S REPORT

� Results of chest radiograph in the morning following institution of NAVA the night before.

� “Significant clearing of infiltrates. What did you do to this patient?”

QUICK TURN AROUND FOR PATIENT

� Morning ABGs while on NAVA at 50% FiO2

� pH = 7.43, PaCO2 = 40, PaO2 = 92 SpO2 = 96%

� After about 14 hours on NAVA they were able to extubate the patient.

� The patient was on the ventilator a total of only three days and was transferred out of the unit the next morning.

Case Review� Physician noted that typically a patient with

aspiration pneumonia and ALI would have been on ventilation for 5-7 days.

� Resolution occurred very quickly following the use of NAVA

� This is a novel case which suggests benefit of the mode NAVA.

� A study done on weaning patients with ARDS

� PS vs NAVA (Terzi N, et al,CCM 2010 vol 38)

� NAVA significantly reduced asynchrony and may help avoid over-assist.

Questions in Neonates

(Howard Stein, MD)

� Is central apnea really ‘central’ in origin?

� Is SIMV (pressure control) in premature infants really ‘synchronized’?

� Is the neural trigger synchronous?

True central apnea in a 1 month old 23 week infant.

Is SIMV (pressure control) in Premature

Infants Really ‘Synchronized’?

Prolonged periods of apnea over an hour

SIMV (pressure control) with EDI superimposed shows the lack of

synchrony on the flow triggered breaths

Is Neural Ventilation synchronous

NAVA in a 1 month old ex 23 week infant.

Patient Case� 28 week old

� Self-extubated following ventilation with NAVA

� Not reintubated but put on high flow therapy

� Edi catheter still in place and used to monitor

Bubble Cpap 7cmH20

Vapotherm 2 lpm

Vapotherm 4 lpm

Vapotherm 6 lpm

Vapotherm 8 lpm

Summary

� Ventilator Asynchrony is a serious and prevalent problem for ventilated pateints.

� Edi allows monitoring of the diaphragm’s activity to evaluate ventilator asynchyrony.

� With the NAVA mode, the patient’s neural center activity (Edi) controls the ventilator.

� Improves patient-ventilator synchrony and reduce work of breathing

� Potential Benefits – less sedation, lung protective, fewer ventilator days, monitor diaphragm fatigue

Providing Ventilation is Lifesaving

The End