What Can We Do For The Patient?

1. Dr Tristan GR Dyer RCSEd Fellow in Pre-hospital Emergency Medicine What Can We Do For The Patient?

2. Aims • To discuss methods of ventilation • To discuss mechanical ventilation • To introduce some difficult patient groups that make ventilation more challenging • To look at future tools to aid ventilatory strategies

3. How Can We Ventilate The Patient? • Let the patient do it themselves! • Manually • Mechanically

4. Self-Ventilation • Deliver oxygen • Work with the patient to optimise their position • Analgesia • Therapeutic interventions (e.g. drugs)

5. Indications for Ventilatory Support • Failure to Ventilate • Failure to Oxygenate

6. Manual Ventilation

7. Manual Ventilation • Can be used with basic and advanced airway adjuncts. BUT • Ties operator up! • Inaccurate tidal volumes. • Tendency for operator to hyperventilate (the patient!) • May not be able to effectively ventilate the patient. • Risk of aspiration.

8. Predictors for Difficult Manual Ventilation

9. Mechanical Ventilation

10. How does it work? • Intermittent application of positive pressure to the upper airway. • Inspiration – gas flows into alveoli until the alveolar pressure equals the upper airway pressure. • Expiration – positive airway pressure is removed/decreased so the gradient reverses and gas flows out of the alveoli.

11. Pre-hospital Mechanical Ventilation • Patient has to be anaesthetised or crash intubation. BUT • Delivers 100% FiO2 • Accurate tidal volumes. • Accurate respiratory rate. • Alarms to warn of emergencies developing. • Allows inline capnography. • Frees up the operator.

12. Modes of Ventilation • Controlled Mechanical Ventilation • Assist-Control Ventilation • Intermittent Mandatory Ventilation • Pressure Support Ventilation • Pressure Control Ventilation • Inverse I:E Ratio Ventilation

13. Controlled Mechanical VentilationCMV

14. Patient Factors To Optimise Ventilation • Ensure adequate sedation and paralysis • Patient position • Clear secretions • Treat underlying pathology

15. Basic Settings • Respiratory Rate 10-12 breaths/min. • Tidal Volume 6-8 ml/Kg. • Aim to balance adequate ventilation with risk of pulmonary barotrauma and volutrauma at inflation pressures of >35-40 cm H2O. • Lower mean airway pressures (<20-30 cm H2O) can help preserve cardiac output and V/Q relationships. • May build TV up to 10ml/Kg.

16. Advanced Ventilators

17. Allow for...

18. Positive End-Expiratory Pressure(PEEP) • Used to improve a symptomatic decrease in the Functional Residual Capacity that causes hypoxaemia. • Provided by an extra valve applied to the breathing circuit or within the ventilator.

19. Pulmonary Effects of PEEP In patients with a reduced lung volume, PEEP stabilizes and expands partially collapsed alveoli. This... • Increases FRC and tidal ventilation • Improves lung compliance • Corrects V/Q abnormalities

20. Adverse Pulmonary Effects • Worse at levels >20 cm H20. • Barotrauma • Worse with underlying lung disease, high rate of breaths, large tidal volumes and young age.

21. Adverse Non-Pulmonary Effects • Transmission of elevated airway pressure to the contents of the chest. • Reduced cardiac output. • Elevated central venous pressure.

22. PEEP Settings • Starting PEEP 5-8 cm H2O used to compensate for the reduced FRC in anaesthetised patients. • Add in increments of 5 cm H2O up to 15 cm H2O. • Aim to improve oxygen saturations.

23. Lung Protective Strategy • Low Tidal Volume • Low Airway Pressure • Modest PEEP

24. Difficult Patient Groups

25. Trauma

27. Asthmatics

28. Pregnant

29. Bariatric

30. Elderly

31. Children

32. The Future

33. Arterial Lines

34. iSTAT

35. Portable Ultrasound

36. Inotropes

37. Any Questions?

38. Summary • Discussed means of ventilation • Focused on mechanical ventilation • Talked about difficult patient groups • Looked at future adjuncts that may help with ventilatory support