1. 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.

2. 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)

3. Ventilator Waveform Identification
Georgopoulos (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?

4. Experts Versus Non-Experts
Columbo, et al, CCM 2011, 39:11
Experts Versus Non-Experts
Columbo, et al, CCM 2011, 39:11

5. Experts Versus Non-Experts
Columbo, et al, CCM 2011, 39:11
Experts Versus Non-Experts
Columbo, et al, CCM 2011, 39:11

6. Experts Versus Non-Experts
Columbo, et al, CCM 2011, 39:11
Synchrony?
Courtesy: Dan Rowley

7. SAME PATIENT SHOWING DIAPHRAGM ACTIVITY
1 2 3
1 2 3
Courtesy: Dan Rowley
PRESSURE SUPPORT –
IS THE PATIENT TRIGGERING THE VENTILATOR?

8. 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?

9. 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

10. 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)

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

12. 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

13. 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 newborn
infants. Cochrane Database of Systematic Reviews 2008, Issue 1. Art.No.:CD000456. DOI:

14. 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.

15. 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

16. 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.

17. 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 newborn
infants. 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…
Propofol

18. 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

19. ECG Waveforms
An ECG is the standard of care for a variety of
patient problems.
What if we could monitor the ECG of the
diaphragm?
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.

20. 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.

21. Edi Catheter Position

22. 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?

23. Low Edi signal
Sedation
Neural disorder
Muscle relaxants
Paralytics
Brain injury or
Brain dead
Hyperventilation

24. High Edi Signal
Increased respiratory drive
High CO2 values or low O2 values
Increased resistance
Increased respiratory
workload
Sigh Breath
Assist/Control Volume

25. Using the Edi to
control the ventilator

26. PC Card
Edi Catheter
What is the Ideal Ventilator?
Laghi, Franco, NAVA: Brain over Machine? Intensive Care Medicine; 2008
“Ideal ventilator should be able to record the activity of
the respiratory neural system, and use that
measurement to select a satisfactory tidal volume. “

28. NAVA in a 1 day old 28 week infant with RDS

29. 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.

30. 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

31. Patient on NAVA Mode
WITHIN 30 MINUTES, SUPPORT REDUCED

32. 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.

33. 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.

34. 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.

35. 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.

36. 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

37. 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.

38. 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?

39. True central apnea in a 1 month old 23 week infant.
Is SIMV (pressure control) in Premature
Infants Really ‘Synchronized’?

40. Prolonged periods of apnea over an hour

41. 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.

42. 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

43. Vapotherm 2 lpm
Vapotherm 4 lpm

44. Vapotherm 6 lpm
Vapotherm 8 lpm

45. 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

46. The End