1. Tutorial: Pulmonary Function--Dr. Bhutani Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support @ 18 hours age: Settings: 18 / 5 cm H 2 0 x 45 breaths / min; FiO 2 = 0.65 Driving Pressure: 18-5 = 13 cm H 2 0 Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaC O 2 = 55 mmHg Is this baby a candidate for permissive hypercapnia?

5. Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support and is now about 18 hours age and has stable vital signs, normotensive and is normoglycemic: Settings: PIP:18 cm H 2 0; PEEP: 5 cm H 2 0; SIMV: 45 br / min; Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaCO 2 = 55 mmHg Is the Alveolar Ventilation compromised? If so, by how much?

6. Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support and is now about 18 hours age and has stable vital signs, normotensive and is normoglycemic: Settings: PIP:18 cm H 2 0; PEEP: 5 cm H 2 0; SIMV: 45 br / min; Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaCO 2 = 55 mmHg PaCO 2 = 55 mmHg is 35% higher than 40 mmHg Alveolar Ventilation is decreased by 35%

7. Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support and is now about 18 hours age and has stable vital signs, normotensive and is normoglycemic: Settings: PIP:18 cm H 2 0; PEEP: 5 cm H 2 0; SIMV: 45 br / min; Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaCO 2 = 55 mmHg PaCO 2 = 54 mmHg is 35% higher than 40 mmHg Questions: Do we wean? Which option?

9. Clinical Case: Use of Tidal Volume 695 g male neonate with RDS, treated with surfactant and on ventilatory support: Settings: 18 / 5 cm H 2 0 x 35 breaths / min Driving Pressure: 18-5 = 13 cm H 2 0 Tidal Volume (measured): = 4 ml (5.7ml/kg) Effective Compliance: =  V /  P ; 5.7 / 13 ml/cm H 2 0/kg Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaC O 2 = 55 mmHg

10. Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support: Settings: 18 / 5 cm H 2 0 x 35 breaths / min Driving Pressure: 18-5 = 13 cm H 2 0 Tidal Volume (measured): = 4.0 ml (5.7 ml/kg) Effective Compliance: =  V /  P ; 5.7 /13 = 0.44 ml / cm H 2 0/kg Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaC O 2 = 55 mmHg

11. Relationship to FRC

13. Clinical Case 695 g male neonate with RDS, treated with surfactant and on ventilatory support: Settings: 18 / 5 cm H 2 0 x 45 breaths / min Driving Pressure: 18-5 = 13 cm H 2 0 Tidal Volume (measured): = 4.0 ml (5.7 ml/kg) Effective Compliance: =  V /  P ; 5.7 /13 = 0.44 ml / cm H 2 0 Arterial Gas: pH = 7.3; Pa O 2 = 74 ; PaC O 2 = 55 mmHg

14. (PEEP) 5 18 (PIP)  P = 13 cm H 2 0  V = 5.7 ml/kg Graphic Representation of Ventilator Settings

15. (PEEP) 5 18 (PIP)  P = 13 cm H 2 0  V = 5.7 ml/kg  V /  P = 5.7 / 13 = 0.44 ml/cm H 2 0 /kg Graphic Representation of Ventilator Settings

16. 5 TLC RV 19  P = Driving pressure  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP 18 17 Linear Change in  V/  P  V /  P = 5.7 / 13 = 0.44 ml/cm H 2 0

17. 5 TLC RV 19  P = Driving pressure  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP 18 17 Imaginary P-V relationship

19. 5 17 18 TLC RV 19 16  P = 12  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP Wean Peak Inflating Pressure Tidal Volume decreases with weaning Driving pressure decreased

21. 5 18 TLC RV 19 17  P = 14  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP 4 Wean PEEP Tidal Volume increases with weaning Driving pressure increased

26. 5 17 18 TLC RV 19 16  P = 13  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP 4 DUAL WEAN: concurrent wean of both PIP and PEEP Tidal Volume increases with weaning Tidal Volume increases with weaning Driving pressure unchanged

27. 5 18 TLC RV 14  P = 10  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP 4 DUAL WEAN that allows for permissive hypercapnia Tidal Volume unchanged with weaning Driving pressure decreased

29. 4 5 17 18 TLC RV 19 16  P  V PRESSURE (cmH 2 0) VOLUME Peak Inflating Pressure PEEP Iatrogenic hypercapnia with inappropriate Dual Wean Tidal Volume decreases with weaning