Patient Ventilator Interaction during Mechanical Ventilation lecture presented by Dr.Lluis Blanch at Pulmonary Critical Care Egypt Meeting and Exhibition, January 2014. www.pccmegypt.com

1. Patient Ventilator Interaction during MV
Lluis Blanch MD, PhD
Senior Critical Care Department
Director Research and Innovation
Corporació Sanitaria Parc Tauli. Sabadell. Spain.
Universitat Autònoma de Barcelona. Spain.
22-23 January 2014 Cairo, Egypt

2. Dissynchrony between Patient & Ventilator
diaphoresis &
nasal flaring
sternomastoid
activity
cyanosis
tachypnea
supresternal &
supraclavicular
recession
abdominal
paradox
intercostal
recession
tachycardia
Tobin MJ. Principles and Practice of MV. 1994.

3. Patient & Ventilator-Related Factors that
Affect Patient-Ventilator Interaction
• Patient related factors
– Respiratory center output
– Respiratory system mechanics
– Disease states & conditions
– Artificial airway in place
• Ventilator related factors
– Triggering
– Cycling off
– Ventilator causes of patient agitation
– Dead space

4. Types of dyssynchronies
Trigger dyssynchrony
trigger delay
autotrigger
inefective inspitarory effort
insufficient airflow
Cycling off dyssynchrony
short cycle
prolonged cycle
double trigger

5. Pressure Support Ventilation. AutoPEEP
ECG
CO2
.
V
Paw
VT

6. Ineffective Inspiratory Efforts During Expiration
Descriptive tracings
ALI Patient
Q
Paw
V
Corretger E, Murias G,… Blanch L. Med Intensiva (2011 Oct 17)

7. PSV: Ineffective Efforts
Flow
(L/s)
Can occur when:
- too much PSV
Paw
-presence of autoPEEP
(cmH2O)
-inadequate triggering
Pes
(cmH2O)
Time (s)
Brochard L. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

8. PSV from
20 to 13 cmH2O
Cycling off 45%

9. Patient-ventilator asynchronies: role of PSV level & flow triggering
Georgopoulos D et al Intensive Care Medicine 2006; 32:34-47

10. Double triggering
VCV
PCV
Double triggering occurs when the ventilator inspiratory time
is shorter than the patient’s inspiratory time
Corretger E, Murias G,… Blanch L. Med Intensiva ((2011 Oct 17)

11. Assist Control Ventilation. Double Cycling
ECG
CO2
.
V
Paw
VT

12. Crit Care Med 2008; 36:3019–3023
Median & IQR of stacked breaths
per minute for each patient.
Breath stacking occurs
frequently. Set TV in
mL/kg PBW has a
strong association with
the frequency of breath
stacking.

13. Crit Care Med 2013;41:2177-87
30 pts with breath stacking:
No Intervention
Increase Sedation/Analgesia
Ventilator Adjustment

14. Crit Care Med 2013;41:2177-87
Change in
Ventilator:
Increase Ti
or
Use PSV

15. Crit Care Med 2013;41:2177-87
Increase Ti from 0.4 s to 1 s
IEE

17. Mechanical Ventilation-Induced Reverse-Triggered Breaths
Reverse triggering & Respiratory Entrainment
Stretch receptors & vagal C fibers are responsible for
the Hering-Breuer reflexes
Akoumianaki E et al. Chest 2013;143:927-38.

18. Short cycle is a cycle in which the inspiratory time
is less than half the mean inspiratory time.
Airflow
Airway
Pressure
Volume

19. Prolonged cycle is a cycle in which the inspiratory time
is more than twice the mean inspiratory time
Airflow
Airway
Pressure
Volume

20. PSV: Prolonged Inspiration
Flow
(L/s)
Results from a failure to
recognize flow cyclingPaw
(cmH2O)
off criterion.
Timax
Can occur when:
- end-inspiratory leak
Pes
(cmH2O)
- wrong cycling off
Time (s)
Brochard L. Principles & Practice of Mechanical Ventilation. Tobin M, ed. 2007

21. Pressure support ventilation
Ti/Ttot during MV
Pes
1s
CO2
.
V
Paw
1s
0.7s

22. Terminal Dyssyncrony
Ti patient > Ti ventilator (PSV)

23. Terminal Dyssyncrony
COPD & PSV
Expiratory muscle
activation
Parthasarathy S et al. Am J Respir Crit Care Med 1998;158:1471-78.

24. Secretions
Airflow
Airway
Pressure
Volume

25. Two type breaths: mandatory SIMV breaths are volumecontrolled (600 mL) and flow-targeted (50 L/min). The nonmandatory breaths are PS (15 cmH2O) with cycling off of 25%
de Wit.Respir Care 2011;56(1):61– 68.

26. J Crit Care. 2009 March ; 24(1): 74–80
In 20 ICU patients airway pressure and airflow were recorded for 15 minutes.
Patient ventilator asynchrony was assessed by determining the number of
breaths demonstrating ineffective triggering, double triggering, short cycling,
and prolonged cycling.
ITI=
ineffectively triggered breaths
total number breaths
For one unit decrease in RASS,
ITI increased by 2.7%, p = 0.04

27. Intensive Care Med. 2006 Oct;32(10):1515-22.

28. Crit Care Med 2009; 37:2740–2745
6 patients had pressure and flow-time waveforms recorded for 10
mins within the first 24 hrs of MV initiation.
Ineffective triggering index (ITI) was calculated by dividing the
number of ineffectively triggered breaths by the total number of
breaths (triggered and ineffectively triggered).

29. Crit Care Med 2009; 37:2740–2745

30. 60 patients included, 55% of whom
were hypercapnic and monitored for
30 minutes.

31. 1. Auto-triggering was present in 8 (13%) patients, double
triggering in 9 (15%), ineffectiv breaths in 8 (13%), premature
cycling 7 (12%) and late cycling in 14 (23%).
2. An asynchrony index (AI) >10%, indicating severe
asynchrony, was present in 26 patients (43%).
3. Multivariate analysis showed that the level of pressure support
(OR: 1.32 per additional cmH2O of pressure support, 95% CI:
1.10–1.58; P = 0.003) and the magnitude of leak (OR: 1.24 per
additional l/min of leak, 95% CI: 1.03–1.48; P = 0.019) were
associated with the presence of an AI >10%.

32. Crit Care Med 2011 Vol. 39, No. 11
Breath Analysis: Paw & Flow waveforms
N-Ex: Non experts (first year residents)
Ex: Experts (ICU physicians)
Report Analysis: Paw & Flow & EADi waveforms
3731 PS breaths evaluated
Visual inspection of flow and airway pressure waveforms provides
a gross estimate of patient–ventilator synchrony

34. Nurse detection of ineffective inspiratory efforts during mechanical ventilation
Chacon E et al. Am J Crit Care. 2012 Jul;21(4):e89-93
Nurse 1 (n=985): SS 93 %; SP 98 %.
Kappa index 0.92 (95%CI: 0.89-0.94).
Nurse 2 (n=970): SS 99 %; SP 85 %.
Kappa index 0.74 (95%CI: 0.70-0.78).

35. Validation of the Better Care® system to detect ineffective
efforts during expiration (IEE) in MV patients: A Pilot Study.
Experts Opinion
EAdi Validation
8 patients; 1024 breaths
8 patients; 9600 breaths
Blanch L et al. Intensive Care Med 2012 (DOI 10.1007/s00134-012-2493-4)

36. Validation of the Better Care® system to detect ineffective
efforts during expiration (IEE) in MV patients: A Pilot Study.
IEE
Compared with the EAdi, the IEE algorithm had a SS of 65.2%, SP
99.3%, PPV 90.8%, NPV 96.5%, and Kappa index 73.9%
Blanch L et al. Intensive Care Med 2012 (DOI 10.1007/s00134-012-2493-4)

37. Patient & Waveforms & Advanced Alarms

38. Neurophysiologic
Model of
Respiratory Discomfort:
Air Hunger
Work/Effort
Tightness
O’Donnell DE et al
Resp Physiol Neurobiol 2009

39. J Neurophysiol 2002;88:1500-1511
Air Hunger Increases MRI Signal in Insula (Limbic System)
Insula (Limbic System):
-Perception of dyspnea, hunger,
thirst
-Afferents of resp. chemoreceptors
-Stretch receptors project to insula
-Seat of emotions
-Large role in memory
Insula
Air hunger may cause severe
psychological trauma

40. Crit Care Med 2011;39:2059-65
45 patients (47%) reported dyspnea (respiratory effort in
seven cases, air hunger in 15, both in 16, and neither of
these in seven).
Dyspneic and nondyspneic patients did not differ in terms of
age, SAPS II or indication for MV.
Dyspnea was significantly associated with anxiety (OR, 8.84;
95%CI, 3.26 –24.0), assistcontrol ventilation (OR, 4.77;
95% CI, 1.60–4.3), and heart rate (OR, 1.33 per 10
beats/min; 95% CI, 1.02–1.75).

41. Physiologic Events
During MV
Discomfort
Dyspnea
- Air Hunger
- Work/Effort
- Tightness
Agitation
Risk of Extubation
Hours

42. The World of Asynchronies during invasive MV
RESPIRATORY CARE • JUNE 2013 VOL 58 NO 6
Am J Respir Crit Care Med Vol 188, pp 1058–1068, Nov 1, 2013
Minerva Anestesiol 2013;79:434-44

43. Project of Intelligent Alarms during MV
Sabadell 5 July 2012

44. lblanch@tauli.cat
Thanks !!