Mechanical ventilation and physiotherapy management @Dr.Muskan Rastogi (PT) BPT,MPT(OBG)

physiotherapy mechanical ventilation

1. Mechanical Ventilation MUSKAN RASTOGI

2. Index Introduction Physiology of normal breathing v/s mechanical ventilation Indication Goals Principles of mechanical ventilation Types of Modes of ventilators Settings of ventilators Adverse effects of 2

3. Introduction Ventilation can be defined as the process of exchange of air between the lungs and the ambient air In the clinical setting, a machine known as a mechanical ventilator is used to perform this function on patients faced with serious respiratory illness. 3

4. Physiology of normal breathing v/s mechanical ventilation Normal breathing Breathing by muscles is governed by requirement of body Initiation and termination of breathing depend on levels of pO2, pCO2, pH and lung inflation. Air gets sucked in because of negative intra pleural pressure created by the respiratory muscles Increase in pulmonary pressures are in the range of 3 to 5cms of water Venous return increases during respiration Expiration is passive Mechanical ventilation Work of the respiratory muscles is done by ventilator Initiation, termination may be machine determined(mandatory breath) or patient determined ( spontaneous breath). Air is pushed in by positive pressure given by the ventilator. Pressures generated are in the range of 15 to 40cms of water. Venous return decreases during respiration Expiration is passive 4

5. Indications Acute Respiratory Failure Hypoxemia Neuromuscular disorders Pulmonary edema Over sedations Reduce ICP Stabilize the chest wall Aspiration ARDS Pulmonary embolism 5

6. GOALS 6

7. Principles of mechanical ventilation A ventilator is machine that generates the pressure necessary to cause a flow of gas that increases the volume of the lungs The 3 variables involved are- Pressure Volume Flow One can be fixed or predetermined and the other two will depend on the compliance of the lungs and the chest wall and the resistance offered by the airways. 7

8. TYPES OF MECHANICAL VENTILATION 8 Ventilatory support that is given through endo-tracheal intubation or tracheostomy is called as invasive mechanical ventilation. Ventilatory support that is given without establishing endo-tracheal intubation or tracheostomy is called non-invasive mechanical ventilation

9. Parts of ventilator 9

10. Settings Mechanical Ventilator Settings regulates the rate, depth and other characteristics of ventilation. Settings are based on the patient’s status i.e., ABGs, Body weight, level of consciousness and muscle strength. Main settings are- Trigger – what initiates a breath Target – what the vent is trying to achieve Cycle – what causes the breath to end 10

11. 1. Fraction of inspired oxygen {FIO 2 } Concentration of oxygen in the inspired air Use the lowest FIO2 that achieves the targeted oxygenation 11

12. 2. Respiratory Rate[RR] Spontaneous breaths taken by the patient 10-20 breaths per minute 12

13. 3. Inspiratory: Expiratory(I:E) Ratio Ratio of duration of inspiration to expiration Normal: longer expiratory phase than inspiratory phase(1:2,1:3) Inverse Ratios provide a longer inspiratory phase(1:1,2:1,3:1,4:1) Reduced I:E allows more time for exhalation and reduces breath stacking Used for patients who have obstructive airway disease with acute respiratory acidosis 13

14. 4. Minute ventilation(V E ) Volume of gas exchanged per minute 5-10L/minute 14

15. 5. Peak Flow Rate[PFR] Maximum flow delivered by ventilator during inspiration 15

16. 6. Peak inspiratory pressure {PIP} Highest proximal airway pressure reached during inspiration Target PIP is <35 cm H 2 O Low PIP may result in hypoventilation; High PIP may cause lung damage 16

17. 7. Plateau pressure(Pplat) Reflects pulmonary compliance and is measured by applying a brief inspiratory pause after ventilation. 17

18. 8. Positive End Expiratory Pressure{PEEP} Pressure remaining in the lungs at the end expiration. Used to keep alveoli open and “recruit” more alveoli to improve oxygenation for patients. High levels may cause barotrauma, increased intracranial pressure, and decreased cardiac output. 3-10cm H 2 O 18

19. 9. Pressure support (PS) Provides additional pressure during inspiration to ensure a larger tidal volume with minimal patient effort Used to help overcome the work of breathing through ventilator tubing 8-20cm H 2 O 19

20. 10. Tidal Volume {V T } Volume of gas exchanged with each breath 6-8mL/kg of ideal body weight [IBW] to prevent barotrauma 20

21. MODES OF VENTILATION

22. Traditionally, physiotherapists have been involved in the respiratory care of patients on mechanical ventilation in ICU.The respiratory care involves optimisation of ventilation, airway clearance, prevention of pulmonary complications, and hastening weaning from mechanical ventilation. Techniques used by physiotherapy to help improve patient breathing and wean patients off ventilators may include: Suctioning Postural drainage Central lavage ( Paediatrics ) Percussion Vibrations 22

23. Continuous Mandatory Ventilation (CMV) In this mode the ventilator provides a mechanical breath on a preset timing. Patient respiratory efforts are ignored.  Trigger –Ventilator initiates all breaths Patient can not initiate Target – Volume Cycle – Time e.g. Settings - Mode: CMV Rate 10; Vt 700cc FIO2 0.5; PEEP 5.0 vent gives cc each patient gets zero extra breaths (even if tries) very uncomfortable for patient only used if patient paralyzed (i.e. in O.R.) 23

24. Assist Control (Volume Control) In this mode the ventilator provides a mechanical breath with either a pre-set tidal volume or peak pressure every time the patient initiates a breath.  Trigger – machine and patient Target – volume Settings-Mode: VC Rate 10; Vt 700cc FIO2 0.5; PEEP 5.0 e.g. vent gives cc each patient initiates 6 bpm – vent provides 700cc 24

25. Synchronized Intermittent Mandatory Ventilation (SIMV) In this mode the ventilator provides a pre-set mechanical breath (pressure or volume limited) every specified number of seconds (determined by dividing the respiratory rate into 60 - thus a respiratory rate of 12 results in a 5 second cycle time). Within that cycle time the ventilator waits for the patient to initiate a breath using either a pressure or flow sensor. When the ventilator senses the first patient breathing attempt within the cycle, it delivers the preset ventilator breath. If the patient fails to initiate a breath, the ventilator delivers a mechanical breath at the end of the breath cycle. SIMV is frequently employed as a method of decreasing ventilatory support (weaning) by turning down the rate, which requires the patient to take additional breaths beyond the SIMV triggered breath. Trigger – ventilator and patient Target – ventilator breaths = set volume patient breaths = patient effort Settings-Mode: SIMV Rate 10; Vt 700cc FIO2 0.5; PEEP 5.0 e.g. vent gives cc each patient takes cc each 25

26. Pressure Control (PC) Trigger – ventilator and patient Target – Pressure (above PEEP) Settings – Mode: PC Rate 10; Pressure 24 cm H2O FIO2 0.5; PEEP 5 e.g. vent gives 10 bpm to a peak Paw = 29 pt takes 6 bpm targeted to peak Paw =29 26

27. Pressure Support Ventilation (PSV) When a patient attempts to breath spontaneously through an endotracheal tube, the narrowed diameter of the airway results in higher resistance to airflow, and thus a higher work of breathing. PSV was developed as a method to decrease the work of breathing in-between ventilator mandated breaths by providing an elevated pressure triggered by spontaneous breathing that "supports" ventilation during inspiration Trigger – patient only Target - pressure Cycle – patient flow decrease Settings – Mode: PSV = 14 cm H2O FIO2 0.4; PEEP 5 e.g. pt takes 18 Vt = 500cc machine gives zero breaths 9/4/20XX Presentation Title 27

28. Completely Unassisted Breaths Trigger – patient Cycle – patient effort ceases Settings: CPAP 5; FIO2 0.4 e.g. patient takes cc each 9/4/20XX Presentation Title 28

29. Continuous Positive Airway Pressure (CPAP) A continuous level of elevated pressure is provided through the patient circuit to maintain adequate oxygenation, decrease the work of breathing, and decrease the work of the heart (such as in left-sided heart failure — CHF). Note that no cycling of ventilator pressures occurs, and the patient must initiate all breaths. In addition, no additional pressure above the CPAP pressure is provided during those breaths. CPAP may be used invasively through an endotracheal tube or tracheostomy or noninvasively with a face mask or nasal prongs. 29

30. BiPAP Noninvasive positive pressure ventilation that delivers a preset inspiratory positive airway pressure and expiratory positive airway pressure The tidal volume correlates with the difference between the IPAP and EPAP 30

31. Adverse Effects of Mechanical Ventilation Pulmonary: Intubation effects Air leaks (pneumothorax/BPF) Ventilator-associated lung injury Ventilator-associated pneumonia Dynamic hyperinflation/Auto-PEEP Cardiovascular: Increased CVP (↑intrathoracic pressure) Decreased venous return Hypotension Increased RV afterload 31 Neuro/muscular: ↑ ICP Prolonged sedation Myopathies Neuropathies Ventilator-Associated Lung Injury (VALI): Volutrauma – overdistension of alveoli Barotrauma – high alveolar pressures Atelectotrauma – repetitive opening and closing of alveoli Biotrauma – release of inflammatory mediators into systemic circulation

32. Procedure of Weaning patient Weaning is gradual reduction of ventilation. A new systematic review suggests that noninvasive ventilation after early extubation helps in reducing the total days spent on invasive mechanical ventilation; also, the patients spending less time on invasive ventilation had lower rates of ventilator-associated-pneumonia. In some cases, this process is rapid and uneventful; however, for some patients the process may be prolonged for days or weeks. Weaning is a term that is used in two separate ways. Firstly, it implies the termination of mechanical ventilation and secondly the removal of any artificial airway. When to wean Normalised I:E ratio Reducing FiO2 (usually <0.5) No requirement for high PEEP Appropriate underlying respiratory rate Appropriate tidal volume with moderate airway pressures 32

33. Physiotherapy Role in Mechanical Ventilation and Weaning Traditionally, physiotherapists have been involved in the respiratory care of patients on mechanical ventilation in ICU. The respiratory care involves optimization of ventilation, airway clearance, prevention of pulmonary complications, and hastening weaning from mechanical ventilation. Techniques used by physiotherapy to help improve patient breathing and wean patients off ventilators may include: Suctioning Postural drainage Central lavage (Pediatrics) Percussion Vibrations 33