1. Performance of ventilators at simulated altitude: study of tidal volume Jean-Pierre Tourtier, Thomas Leclerc, Marc Borne Military hospital Val-de-Grâce, Paris, France. Service de Santé des Armées

2. Introduction (1):  Aero medical evacuation: ventilatory support  Pulmonary impairments  Ventilators: turbine technology  Hypobaric

3. Introduction (2):  2 ventilators: T-bird VS02 LTV-1000

4. Methods (1):  Cabin altitude simulation

5. Methods (2):  Altitude simulated:  1500 m (4000 feet)  2500 m (6700 feet)  3000 m (3000 feet)

6. Methods (3):  Lung simulation: VT1 Bioteck  Normal lung: (resistance : 5.6 cm H 2 O/L/min ; compliance : 50 ml/cm H 2 O)  Acute Respiratory Distress Syndrom (resistance : 3.9 cm H 2 O/L/min ; compliance : 20 ml/cm H 2 O)

7. Methods (4):  Ventilation parameters: Lung modelNormal lungARDS Vt set (ml)700, 400400, 250 Respiratory rate 1220 I/E1/21/1 Fi02 (%)21,50,90100

8. Methods (5):  Measurements:  Actual Vt: Fleisch pneumotachograph / computer  Actual respiratory rate  Statistic analyze:  3 measures  Mean +- SD  t test (Vt set vs Vt delivered): p <0.05

9. Results (1): Normal lung: T-bird VS02 Vt=700 ml

10. Results (2): Normal lung: T-bird VS02 Vt=400 ml

11. Results (3): Normal lung: LTV-1000 Vt=700 ml

12. Results (4): Normal lung: LTV-1000 Vt=400 ml

13. Results (5): ARDS: T-bird VS02 Vt=400 ml

14. Results (6): ARDS: T-bird VS02 Vt=250 ml

15. Results (7): ARDS: LTV-1000 Vt=400 ml

16. Results (8): ARDS: LTV-1000 Vt=250 ml

17. Conclusion (1): T-bird VS02  With altitude: Vt decreased  Significantly:  Normal lung model: 700 ml:2500m 400 ml: 2500m  ARDS: 400 ml:1500m 250 ml: 1500m  > 10%

18. Conclusion (2): LTV-1000  With altitude: Vt increased  Significantly:  Normal lung model: 700 ml:1500m 400 ml: 2500m  ARDS: 400 ml, Fi02 50% : at 2500 m  Mostly within 10% of the set Vt