1. Ventilator Auto-Triggering and Brain Death
Tammy Kundinger RRT
UWHC Respiratory Therapy Supervisor
Paula Breihan RRT

2. Objectives Identify how impaired brainstem function alters
respiratory drive
Identify causes of auto triggering with mechanical ventilators
Understand recommendations to eliminate auto- triggering

3. Uniform Determination of Death Act (UDDA)
The act reads as follows: “An individual who has sustained either 1) Irreversible cessation of circulatory and respiratory functions, or 2) Irreversible cessation of all functions of the entire brain, including the brain stem, is dead.”

4. Brain Stem Function
*It serves as a connector between the brain and other organs of our body.
*It’s made up of three parts: midbrain, medulla oblongata and pons.

5. Midbrain: Controls the Visual and Auditory Systems
The movement of eye muscles
The movement of voluntary muscles
The respiratory muscles
It also…
Regulates autonomic functions and awareness
Regulates body temperature

6. Medulla Oblongata: Performs the Following Functions
Respiratory Center
Controls the movement of respiratory muscles
Regulates the rate of respiration
Vasomotor Center
Regulates blood pressure
Reflex Center
Regulates reflex actions like sneezing, coughing, swallowing, etc

7. Pons: Controls Automonic Functions
Regulates sleep patterns
Controls arousal functions like waking up or being alert

8. American Academy of Neurology (AAN) Clinical Guideline for Determining Brain Death in Adults
Establish irreversible and proximate cause of coma
Achieve normal core temperature
Achieve normal systolic blood pressure (> 100 mmHg)
Perform one neurologic exam
*Usually several hours after brain insult
*Some state statutes require 2 examinations

9. Determination of Brain Death
These three parameters are necessary to confirm irreversible functions of the brain:
Coma
Absence of brainstem reflexes
Apnea

10. Neurologic Assessment
Coma: Patients must lack all evidence of
responsiveness
Absence of brainstem reflexes:
No pupillary response
No ocular movements
No corneal reflex
No facial muscle movements
No pharyngeal and tracheal reflexes

11. Neurologic Assessment Apnea Testing
Positive Apnea Test
Respiratory movements are absent
Arterial PCO2 is > 60 mmHg (or 20 mmHg increase in arterial PCO2 over baseline)
Inconclusive Apnea Test
No appropriate rise in PCO2 over the baseline
If the patient is hemodynamically stable during the procedure the test may be repeated for a longer period of time (10-15 minutes)

12. How to Perform an Apnea Test
1. Obtain baseline ABG and normalize PaCO2
(34-45mmHg) prior to testing
2. Preoxygenate for at least 10 minutes with
100% oxygen.
3. Disconnect patient from the ventilator
4. Preserve oxygenation by inserting a catheter
into the endotracheal tube delivering 6 l/min
oxygen.
5. Monitor patient closely for respiratory
movement for 8-10 minutes
6. If no respiratory drive is observed, repeat blood gas
after approximately 8 minutes.

13. Ancillary Tests EEG Cerebral Angiography Nuclear Scan
Transcranial Doppler

14. Consequences of Delayed Brain Death Diagnosis
Prolonged ICU stay for patients’ families
Confusion for family
Ventilator triggering may question the diagnosis of brain death
Cardiac autotriggering may raise false hope of recovery
May lead to increased ICU costs
Longer ICU time may lead to losing potential transplantable organs
Formal brain death protocols may take as long as 6-24 hours

15. What should you do if the neurologic assessment has been completed and the patient has met all criteria for brain death but it looks like -
The patient has finger tremors?
The patient has toe/plantar flexions?
The patient has an intrinsic respiratory drive?

16. Extremity Tremors & Flexion…
Transient bilateral finger tremor
Potential simultaneous toe reflex
Retained flexion stimulation (plantar flexion)
Occurs in more than 50% of patients

17. Autotriggering Phenomenon
The AAN attests that autotriggering (or ventilator self-cycling) occurs when a ventilator breath is triggered in the absence of effort by the patient.

18. Potential Causes of Ventilator Autotriggering
Extrinsic Causes
Random artifact in the ventilator circuit
Water condensation in the ventilator circuit
Ventilator circuit leak
Endotracheal tube cuff leak
Excessive retraction of an inline suction catheter
Intrinsic Causes
Cardiogenic oscillations
Bronchopleural fistula
Chest tube leak

19. How to Correct Extrinsic Factors
Ventilator artifact?
Condensation in ventilator circuit?
Leak in ventilator circuit?
ETT cuff leak?
Misplaced inline suction catheter?

20. Autotriggering Caused by a Leak20

21. How Are You Going to Fix Intrinsic Factors?
Cardiogenic oscillations
Is it fixable?
Bronchopleural fistulas
How can you correct? Optimize your ventilation pressures.
Chest tube leak
Reposition chest tube, obtain CXR to determine position, redress chest tube site, and increase bias flow on ventilator
End result…intrinsic factors may prove to be more difficult to correct or even identify.

22. What Causes Cardiogenic Oscillation?
Physical changes associated with brain death include:
*Hyperdynamic cardiovascular state
*Altered vasomotor tone
This may produce a
hyperdynamic pericardium
which can be mistaken
for respiratory movement

23. Hyperdynamic cardiovascular state
Displace intrathoracic volume & lung tissue
Causing cardiogenic oscillation beyond the
set trigger sensitivity
Triggering ventilator breaths in the absence
of an intrinsic respiratory drive

24. Fluctuations in ventilator airway pressure, flow and potentially volume waveforms in time with the cardiac cycle

25. Cardiogenic oscillations may be seen in greater amplitude in patients with a more hyperdynamic cardiovascular system.

26. Autotriggering Study by Wijdicks
83 patients
4 patients occasionally triggered the ventilator
Autotriggering was eliminated by the adjustment of ventilator trigger or by changing the trigger from flow to pressure.

27. How a Breath is Delivered
Pressure Triggered
The patient’s inspiratory effort causes a drop in pressure within the breathing circuit
Flow Triggered
The ventilator detects a drop in flow through the patient circuit during exhalation 27

28. How a Breath is Delivered
Flow Triggered
Between breaths, the flow coming out of the main flow control valve and the flow going through the exhalation valve are equal
During the patient’s inspiratory effort, the flow through the exhalation valve falls below the flow from the output valve
The difference between these two flows is the flow trigger variable
Continuous flow through circuit: “Base flow” 28

29. Flow vs. Pressure Triggering
Normally, a ventilated patient would be set on flow triggered sensitivity
Flow triggering is more sensitive than pressure triggering
Flow triggering is designed to ease the patient’s work of breathing by requiring less inspiratory effort

30. Importance of Interdisciplinary Team Approach
An appropriate neurologic assessment
Working together and utilizing the expertise of the interdisciplinary team, the organ procurement process can be improved
Early identification of potential ventilator autotriggering can –
Minimize ICU stay
Reduce costs of care
Decrease family stress
Facilitate recovery of transplantable organs

31. UWHC Practice Implementations for Successful Organ Procurement
End of Life Sustaining Measures Order Set
Donation after Cardiac Death Order Set (DCD)
Brain Dead Donor Order Set (BDD)
These order sets have specific algorithms that RT uses as a guide for the type of end of life ventilator management that is indicated in each patient scenario.

32. UWHC Respiratory Care Brain Dead Donor Ventilator Management Algorithm32

33. Example patient scenario of how the BDD lung protective algorithm helps guide the RT in their management of the ventilator and
assessment of the patient in preparation for
organ procurement.
12/5 at 1800 arrived in ED &
then transferred to ICU
12/5 at 2220 apnea test ordered
12/6 at 0410 patient pronounced brain dead
12/6 at 0432 BDD order set initiated
12/6 at 0916 bronchoscopy ordered

34. 12/6 at 2001 oxygen challenge ordered
12/7 at 0140 patient taken to OR for organ donation
In this example, the process took a
very short amount of time from when the patient was admitted to actual OR time for organ procurement. Behind the scenes, this algorithm helps the process
flow more smoothly and eliminates questions and reduces response time to new orders.

35. Questions? Tammy Kundinger UWHC RT Supervisor – Neuro ICU
Paula Breihan
UWHC RT Supervisor – TLC ICU

36. Sources
Araullo, M., Frank, J., & Goldenberg, F. (2007). Transient bilateral finger tremor after brain death. Neurology, 68, 22.
Arbour, R. (2012). Confounding factors in brain death: Cardiogenic ventilator autotriggering and implications for organ transplantation. Intensive and Critical Care Nursing, 28(6),
Arbour, R. (2009). Cardiogenic Oscillation and Ventilator Autotriggering in Brain-Dead Patients: A Case Series. Am J Crit Care, 18, doi: /ajcc
De Wit, M. (2011). Monitoring of Patient-Ventilator Interaction at the Bedside. Respiratory Care, 56 (1),
Dodd-Sullivan, R., Quirin, J., & Newhart, J. (2011). Ventilator autotriggering: a caution in brain death diagnosis. Progress in Transplantation, 21(2),
Wijdicks, EFM, Varelas, P., Gronseth, G., & Greer, D. (2010). Evidence-based guideline update: Determining brain death in adults: Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology, 74,
Widjicks, EFM, Manno, E., & Holets, S. (2005). Ventilator self-cycling may falsely suggest patient effort during brain death determination. Neurology, 65, doi: /01.wnl
Zubkov, A. & Wijdicks, EFM. (2008). Plantar flexion and flexion synergy in brain death. Neurology, 70, 74.