Ventilation-1.pptx..............m..m......

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1. Mechanical Ventilation

2. Indications Respiratory Failure Cardiopulmonary arrest Trauma Events Cardiovascular impairment Neurological impairment Pulmonary impairment Procedures requiring sedation/paralysis

3. Contra-Indications Risks outweigh benefits, for example Neutropenia Non-invasive deemed preferable to invasive ventilation Invasive ventilation considered medically futile Contrary to the expressed wishes of the patient

4. Ventilators A machine that generates a controlled flow of blended air and oxygen into a patient’s airway .

5. Ventilation Two categories Volume or Pressure This refers to the mode of breath delivery rather than the mode itself

6. Volume In volume category modes of ventilation the machine generates flow to achieve a set volume known as TIDAL VOLUME

7. Tidal Volume V T Definition – ‘ the volume of air that is inspired or expired in a single breath during regular breathing’

8. Volume Modes Advantages Guaranteed Minute Ventilation ( Mv ). Disadvantages Increased monitoring of airway pressures. Airway pressures will increase if lung compliance decreases. Risk of barotrauma .

9. Minute Ventilation M V Definition – ‘The total volume of gas in litres expelled from the lungs per minute’

10. Pressure In pressure modes of ventilation a pressure limit is set, the machine generates flow until the peak pressure limit is achieved- PAP or PIP Peak Airway ( inspiratory ) Pressures

11. Peak Airway ( Inspiratory ) Pressures P ip P ap P peak Definition – ‘ Peak Airway ( Inspiratory ) Pressure is the highest level of pressure applied to the lungs during inhalation expressed in cmh 2 o’

12. Pressure Modes Advantages Greater control of airway pressure. Less risk of barotrauma. Disadvantages No guaranteed minute ventilation. Increased monitoring of V T required. Rapid changes in the compliance can cause hypoventilation/hypoxia.

13. Inspiration FLOW TRIGGER - a breath is generated when the patient’s respiratory effort causes flow to reach a set level. PRESSURE TRIGGER - a breath is generated by measuring pressure and starting assisted ventilation when pressure reaches a given level. TIME TRIGGER - a breath is generated by measuring frequency of respirations and starting ventilation when respirations frequency is at a given.

14. Expiration TIME CYCLED - such in pressure controlled ventilation FLOW CYCLED - such as in pressure support VOLUME CYCLED - the ventilator cycles to expiration once a set tidal volume has been delivered: this occurs in volume controlled ventilation.

15. IPPV Set: TV, rate, Fi02, PEEP, No capacity for the patient to trigger a breath Uncomfortable if patient not fully sedated &/ paralysed Suitable only for patients who have no ability to breathe spontaneously

16. S imv S ynchronized I ntermittent M andatory V entilation Provides a set TIDAL VOLUME at a set RATE ( F ) Patient can breathe in-between mandatory ventilation Spontaneous breaths are supported with pressure support Ventilator synchronises mandatory breaths and spontaneous breaths for increased patient comfort NB Usually volume targeted but some machines offer SIMV(pc)

17. SIMV Guaranteed Minute Ventilation Increased monitoring of airway pressures. Airway pressures will increase if lung compliance decreases. Risk of barotrauma. Advantages Disadvantages

18. Spontaneous Modes of Ventilation

19. Spontaneous Modes of Ventilation Spontaneous modes are- Triggered Cycled -By the patient

20. Pressure Support or ASB The patient triggers the ventilator and receives a supported breath at a pre-set pressure. This helps overcome the increased work of breathing or resistance of breathing through an endotracheal tube.

21. Complications of invasive ventilation Airway: Aspiration pneumonia Trauma to trachea during intubation Hypoxia prior to / during intubation Laryngeal oedema Occlusion of blood supply to trachea (if cuff pressures to high) Sinus infection

22. Complications of invasive ventilation Mechanical: Ventilator malfunction. Ventilator circuit: occlusion, kinks, bronchospasm, disconnection & biting. Barotrauma / Volutrauma can rupture alveoli, causing pneumothorax.

23. Complications of invasive ventilation Decreased cardiac output: Induction agents Changes intrathoracic pressure & reduces venous return Cardiac output falls, BP drops CVP and LV preload rise This has implications for the perfusion of all vital organs: brain, kidneys, GI tract

24. Complications

25. PEEP Maintains pressure within the breathing circuit at a pre-set level at the end of expiration When used during spontaneous respiration it is called CPAP A degree of PEEP should be applied on all ventilation modes to minimise risk of atelectasis

26. Inspiration time : Expiration time I:E ratio is 1:2 Can be reversed – 1:1 or less: 2:1 Some machines automatically alter I:E ratios when the set resp rate is altered.

27. Reversing the I:E Ratio Air trapping from increased intrathoracic pressure Hypercarbia ( Î C02) Breath stacking Extreme discomfort for the pt Reduction in cardiac return Advantages or reversing the I:E ratio: Alveolar recruitment Reduced alveolar collapse due to shorter expiratory times Increased mean airway pressure without increasing PAP Disadvantages Advantages

28. Weaning off ventilator

29. Thank you