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, Denmark2: Anaesthesia and Intensive Care, Region North Jutland, Aalborg Hospital, Aarhus University, Denmark

Introduction

• 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?

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

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.

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?

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)

Results

• What is the variability in physicians’ preferences in the same patient? Example: Vt

Variability in physicians’ preferences

6 ml/kg

8 ml/kg

Variability in physicians’ preferences

6 ml/kg

8 ml/kg

Results

• What is the variability in physicians’ preferences in the same patient? Example: Vt

• What are physicians’ opinion about other physicians’ advice?

Opinion’s about other physicians’ advice

Classification Average (range)

Good 21.2 % (9.9% – 26.0%)

Acceptable 45.5 % (36.4% – 56.8 %)

Unacceptable 33.3 % (25.4% – 39.9 %)

Opinion’s about other physicians’ advice

Classification Average (range)

Good 21.2 % (9.9% – 26.0%)

Acceptable 45.5 % (36.4% – 56.8 %)

Unacceptable 33.3 % (25.4% – 39.9 %)

Rank Best Worst

Average 5.0 7.1

Range 2-10 2-10

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?

Opinion about INVENT’s advice

Classification Average (range) INVENT

Good 21.2 % (9.9% – 26.0%) 26.0 %

Acceptable 45.5 % (36.4% – 56.8 %) 41.0 %

Unacceptable 33.3 % (25.4% – 39.9 %) 34.0 %

Opinion about INVENT’s advice

Classification Average (range) INVENT

Good 21.2 % (9.9% – 26.0%) 26.0 %

Acceptable 45.5 % (36.4% – 56.8 %) 41.0 %

Unacceptable 33.3 % (25.4% – 39.9 %) 34.0 %

Rank Best Worst INVENT

Average 5.0 7.1 5.3

Range 2-10 2-10 3-10

Conclusions

• Physiological models may be a beneficial tool for quantifying clinical preferences– Separate variation in preference from variation in patient

pathophysiology

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

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

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

Thank you.