C Allerød 1,2 , DS Karbing 1 , P Thorgaard 2 , S Andreassen 1 , S Kjærgaard 2 , SE Rees 1

1. Use of the INVENT system for standardized quantification of clinical preferences towards mechanical ventilation C Allerød1,2,DS Karbing1, P Thorgaard2, S Andreassen1, S Kjærgaard2, SE Rees1 1: Center for Model-based Medical Decision Support, Aalborg University, Denmark 2: Anaesthesia and Intensive Care, Region North Jutland, Aalborg Hospital, Aarhus University, Denmark

2. Introduction The ARDS Network. N Engl J Med 2000; 342:1301-8. Young et al. Crit Care Med 2004; 32:1260-5. Esteban et al. Am J respir Crit Care Med 2008; 177:170-7 • Several RCTs indicate that low tidal volumes are beneficial in mechanically ventilated patients • Large variability in ventilator settings are still seen in the ICU • But how well do physicians agree when presented to identical patients?

3. Using INVENT for quantifying preferences • INVENT: Model-based decision support system for mechanical ventilation • Advice on FiO2, Vt and f. J Clin Monit Comput 2006; 20:421-9. J Crit Care 2010; 25:367-74.

4. Research questions What is the variability in physicians’ preferences in the same patient? What are physicians’ opinion about other physicians’ advice? What are the physicians’ opinion about INVENT’s advice?

5. Methods • Included 10 senior ICU physicians, representing the 4 Danish University Hospitals • 10 real patient cases, presented in random order • Reflecting range of respiratory, circulatory and metabolic status in patients with ALI/ARDS • Asked to set FiO2, Vt and f • Assuming correct PEEP and I:E ratio, 70 kg body weight and that model simulations were correct • Evaluated and ranked other physicians’, and INVENT’s advice (blinded, and in random case order)

6. Results What is the variability in physicians’ preferences in the same patient? Example: Vt

7. Variability in physicians’ preferences 8 ml/kg 6 ml/kg

8. Variability in physicians’ preferences 8 ml/kg 6 ml/kg

9. Results What is the variability in physicians’ preferences in the same patient? Example: Vt What are physicians’ opinion about other physicians’ advice?

10. Opinion’s about other physicians’ advice

11. Opinion’s about other physicians’ advice

12. Results What is the variability in physicians’ preferences in the same patient? Example: Vt What are physicians’ opinion about other physicians’ advice? What are the physicians’ opinion about INVENT’s advice?

13. Opinion about INVENT’s advice

14. Opinion about INVENT’s advice

15. Conclusions • Physiological models may be a beneficial tool for quantifying clinical preferences • Separate variation in preference from variation in patient pathophysiology

16. Conclusions • Physiological models may be a beneficial tool for quantifying clinical preferences • Separate variation in preference from variation in patient pathophysiology • Large variability found in physicians’ preferences towards appropriate levels of Vt, FiO2, f, PIP, SaO2 and pH

17. Conclusions • Physiological models may be a beneficial tool for quantifying clinical preferences • Separate variation in preference from variation in patient pathophysiology • Large variability found in physicians’ preferences towards appropriate levels of Vt, FiO2, f, PIP, SaO2 and pH • When a physician’s advice was evaluated by other physicians, a third were found unacceptable

18. Conclusions • Physiological models may be a beneficial tool for quantifying clinical preferences • Separate variation in preference from variation in patient pathophysiology • Large variability found in physicians’ preferences towards appropriate levels of Vt, FiO2, f, PIP, SaO2 and pH • When a physician’s advice was evaluated by other physicians, a third were found unacceptable • INVENT ranked third best, evaluated similar to physicians • Prospective testing is necessary

19. Thank you.