The document discusses closed-loop ventilation in intensive care units. It defines closed-loop ventilation as using automated adjustments to certain ventilator settings based on monitored patient parameters. Potential parameters for closed-loop control include respiratory muscle support, ventilation, and oxygenation. Both positive and negative closed-loop control are described. Commercially available closed-loop solutions aim to improve patient-ventilator synchrony, decrease workload, and reduce weaning duration. While offering advantages, closed-loop ventilation also presents technical and implementation challenges that require further study.

1. Dr Jean-Michel Arnal Intensive Care Unit. Hôpital Font Pré Toulon France [email_address] Close loop ventilation in the ICU

2. Definition Conventional ventilation: All the settings are done manually by the user Closed loop ventilation: Some settings are adjusted automatically according to parameters monitored

3. What parameter to close the loop? Non or little invasive Accurate in most condition Reproducible Technology integrated in a ventilator Not too expensive

4. What parameter to close the loop? Respiratory muscle support: patient effort RR, flow, EMG activity of diaphragm Ventilation: Expiratory time constant, E T CO 2 Oxygenation: SpO 2

5. Positive close loop control C ontroller  = i’ x i Valves Signal: Flow= i’ Gain = i P insp Unstable Add complexity Act as auxiliary respiratory muscle Intrabreath

6. Negative close loop control C ontroller  = i– i’ Valves Signal: V T actual = i’ V T Target = i P insp Target can be achieved Fast response Adapts to external modifications Interbreath

7. Determination of the target C ontroller  = i– i’ Valves Signal: V T actual = i’ V T Target = i P insp Operator set Automatically determined

8. What is the target based on? Physiology: Measurement of a physiologic parameter and algorithm that reproduces physiologic process Knowledge: Algorithm that reproduces expert clinical practice

9. Technical challenges Initiation of ventilation: the first breath problem Manual adjustment of the target Weaning: how to use close loop to wean faster? Safety features: limits of settings, lost of signal… User interface: avoiding the black box effect

10. Advantages Adapts timely ventilation delivered to lung condition Increases safety Helps to apply recommendations Improves patient ventilator synchrony Decreases weaning duration Decreases workload Decrease false alarms…

11. Disadvantages Avoids to apply recommendation Increases weaning duration Lost of knowledge, lost of practice Hide the incident Define limits and contraindications Use a weaning protocol Use for teaching Adapt monitoring

12. Commercially available solutions Controlled mode Assisted mode Spont mode PAV NAVA SmartCare Adaptive Support Ventilation IntelliVent®

13. Pinsp regulated in proportion of patient inspiratory flow PAV + : Automatic determination of compliance and resistances Improve patient ventilator synchrony and sleep quality Decreases numbers of manual adjustments Proportional assist ventilation Bosma. Crit Care Med 2007 Xirouchaki. Intensive Care Med 2009

14. Pinsp regulated in proportion of EMG activity of diaphragm Improve patient ventilator synchrony in NIV using the helmet Improve patient ventilator synchrony in neonatology Neurally adjusted ventilatory assistance Moerer. Intensive Care Med 2008 Beck. Pediatr Res 2009

15. Improve patient ventilator synchrony Terzi. Crit Care Med 2010 n = 11

16. Increase variability of ventilation Coizel. Anesthesiology 2010 n = 12 n = 12 Schmidt. Anesthesiology 2010

17. Knowledge based adjustment of pressure support SmartCare

18. Decreases weaning duration Lellouche. AJRCCM 2006 n = 144 patients, ventilation > 24 h

19. SmartCare n = 102 Rose. Intensive Care Med 2008 Weaning success: Control: 40 h (14 – 87) Smartcare: 43 h (6 – 169)

20. Adaptive Support Ventilation Ventilation Oxygenation Conventional ventilation ASV MV V T RR FiO 2 PEEP MV V T RR FiO 2 PEEP

21. Background The optimal respiratory rate 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 0 10 20 30 40 50 WOB res WOB el WOB tot 1+2a* RCe *( VM -f*( V‘D/VD )) - 1 f -target = a* RCe Respiratory rate (cycle/mn) WOB (Joule/sec) Otis AB.J Appl Physiol 1950

22. Evaluation of patient (RCexp and RRspont ) Clinician sets minute ventilation Calculation of target RR and V T The close loop algorithm Adjust Pinsp et RR reach the target

23. Ventilation delivered * p ≤ 0,05 versus normal Arnal. Intensive Care Med 2008 Normal COPD Chest wall stiffness ARDS n (d/patients) 706 / 140 217 / 40 54 / 13 136 / 36 RC exp (s) 0,78 ± 0,28 1,13  0,72* 0,41  0,16* 0,55 ± 0,21 * Vt/PBW (ml/Kg) 8,3  1,3 9,4  2,1* 7,1  1,1* 7,6  1,3 * RR (c/mn) 17  5 16  7 23  7* 20  6 * I/E 0,5  0,2 0,4  0,2* 0,5  0,2 0,63  0,27 *

24. Ventilation delivered Arnal. Intensive Care Med 2008

25. ASV in ARDS patients Study on model reproducing 108 simulated scenario: ASV delivers around 6 mL/Kg PBW for most of cases Same plateau pressure than ARDSnet strategy Lower V T for the most severe cases with lower Pplat Clinical study on 51 ARDS patients: V T delivered are in line with recommendations Pplat was ≤ 28 cmH 2 O Sulemanji. Anesthesiology 2009 Arnal. AJRCCM 2007 [abstract]

26. ASV and weaning Results: MV duration (h) n Control ASV p Sultzer Anesthesiology 2001 36 4,0 3,2 p < 0,02 Petter Anesth Analg 2003 34 3,2 2,7 NS Gruber Anesthesiology 2008 48 8,0 2,7 P < 0,05 Dongelmans Anesth Analg 2009 121 16,3 16,2 NS

27. ASV and weaning in COPD Kirakli. Eur Respir J 2011 n = 97

28. ASV and weaning in ICU Study in medical ICU Weaning performed by RT Comparison of two periods: PS and ASV Extubation readiness on day 1: 20% in ASV, 5% in PS Faster weaning in ASV: 1 day in ASV vrs 3 days in PS Chen. Resp Care 2011

29. IntelliVent Ventilation Oxygenation Conventional ventilation ASV IntelliVent ® MV V T RR FiO 2 PEEP MV V T RR FiO 2 PEEP MV V T RR FiO 2 PEEP

30. IntelliVent

31. IntelliVent

32. Randomized control trial: Provide an automatic weaning in post cardiac surgery patients with less manipulations and more time spent in optimal ventilation zones than PS. Randomized cross-over study: Safe in ICU patients with less inspiratory pressure and V T than ASV with same gas exchanges. IntelliVent Arnal. Intensive Care Med 2010 [abstract] Lellouche. Intensive Care Med 2010 [abstract]

33. Limitations Patient’s response to changes in ventilator setting is hardly predictable Different clinical situations: Any algorithm won’t meet all the situations Different practice: Any algorithm won’t meet all the expectations

34. In practice Available and usable For easy to ventilate patients or after the acute phase Advantages: homogeneity in care, safety, less manipulation, improve organization… But: Learning curve: start with easy patients Must be associated with a weaning protocol

35. Which one to choose? Patient ventilator synchrony: PAV or NAVA Weaning duration: SmartCare ASV: Individualized breath pattern Automatic switch between control and assisted ventilation Reduction of weaning duration IntelliVent…

36. Conclusions Available, usable and safe Lot of potential interest: individual care, organization… Different solutions with increasing complexity Teaching and research tool Clinical evidences are needed before large implementation Thank you… 