Mechanical Ventilation basics and modes(7).pptx

Mechanical ventilation basics

1. Basics of Pediatric Mechanical Ventilation Dr Saira Arshad Fellow Pediatric Critical Care

2. Objectives Recognition of respiratory failure Definition of artificial ventilation Indications Classification of different modes of ventilation Weaning from ventilation

3. Functions of respiration Exchange of oxygen ( O2 ) and carbon dioxide (CO2) between the body and the external environment

4. Respiratory Failure

5. Things to do before mechanical ventilation Airway: check patency, re position, suction Airway adjuncts (OPA, NPA) Supplemental Oxygen.

6. What does Mechanical ventilation mean? Assisted Ventilation which involves the delivery of flow and pressure to the patient’s airway in order to affect change in lung volume”

7. Indications Respiratory Respiratory failure due to Upper airway obstruction Lower airway obstruction Lung tissue disease Apnea or respiratory arrest Non respiratory Shock or cardiac failure– to decrease oxygen consumption, eliminate work of breathing, as inotrope Post- anesthesia Coma Inability to protect airway Neuro- muscular failure like GBS, botulism

8. Goals of Mechanical Ventilation Achieve and maintain adequate pulmonary gas exchange Minimize the risk of lung injury Reduce patient work of breathing Optimize patient comfort To normalize blood gases and provide comfortable breathing

9. Phase Variables Trigger mechanism What causes the breath to begin? Limit variable what limits the delivery of gas to the patient during the inspiratory phase (pressure or volume). Cycle mechanism What causes the breath to end? what cycles, or changes, the ventilator from one phase of the respiratory cycle to the other

10. Types of Breaths

11. Mode of ventilation Control vs SIMV

12. Types of Ventilator Breaths 17 Type Trigger Limit Cycle Mandatory M M M Assisted P M M Supported (SIMV) P M P Spontaneous P P P

13. Volume vs. Pressure Control Ventilation Volume Ventilation Volume delivery constant Inspiratory pressure varies Inspiratory flow constant Pressure Ventilation Volume delivery varies Inspiratory pressure constant Inspiratory flow varies When do you use pressure or volume control ventilation ? Old fashion In general pressure control in babies and small infant < 6- 8 kg In general volume control in children and adolescence > 8- 10 kg Depends upon tradition, comfort & disease.

14. Pressure Control Ventilation

15. Volume Control Ventilation

16. Pressure Support Ventilation It is a spontaneous mode of respiration The patient initiates every breath, and the ventilator supports according to a preset pressure, to overcome airway Patients also regulate their own respiratory rate and tidal volume

17. Ventilator Basics parameters FiO2 : I time : I:E Ratio: cycle time PEEP: Rate : vT : PIP : Sensitivity : Fraction of inspired oxygen The time spent in the inspiratory phase of the ventilatory cycle The inspiratory time compared to the expiratory time; I + E = total Positive end expiratory pressure Number of breaths per minute Volume of each breath Maximum amount of pressured delivered during each breath How responsive the ventilator is to the patient’s efforts

18. Minute Ventilation 12 Minute Ventilation: Tidal volume (VT) x Breathing Frequency (F) Tidal Voulme (TV) = ml/Kg (Dead space Volume + Alveolar Space Volume) Frequency (Rate) = Number of Breaths/min (Inspiratory Time + Expiratory Time)

19. Initial Settings Rate: start with a rate that is somewhat close to physiological i.e 15 for adolescent/child, 20-40 for infant/small child vT : 8- 10 ml/kg for healthy lungs, 4-6 for diseased lungs FiO2: PEEP: 100% and wean down 4-6 or more Pressure support : 8- 10 Determine the mode: Control every breath (A/C) or Some (SIMV)

20. Initial Settings on MV Newborn Infant Toddler/Child Adolesce nt Wt. (Ideal) < 4 kg 4-10 kg 10-40 kg > 40 kg VT mandatory ml/kg (VCV) Normal Lungs (6- 7 kg) Dis.Lungs (3- 5 kg) Normal Lungs : 6- 8 Diffuse Lung Disease : 5-7 Inc. VT / Dec. RR strategy : 8- 12 PIP mandatory (PCV) 18- 25 cms H2O : Adjust to achieve target TV Normal Lungs : Start with lower PIP Diseased Lungs : Start with higher PIP Avoid PIP > 30 cms H2O unless evidence of Dec. chest wall compliance. Ti (sec) 0.3 – 0.4 0.4 – 0.7 0.7 – 0.9 0.9 – 1.2 FiO2 (%O2) 1.0 unless contraindicated ; Adjust to maintain target SpO2 / PaO2 Rate (bpm) 20 – 40 20 – 30 15 – 25 12 - 20 PEEP (cms H2O) 3 – 5 5 – 7 5 – 7 5 - 7 Trigger (Lit / min) 0.25 – 0.50 1.0 – 2.0 PS (cms H2O) Minimum level 8 – 10 cms H2O ; Adjust to achieve target Vt (5 – 7 ml / kg)

21. Adjustments To affect oxygenation, adjust: –FiO2 –PEEP –I time –PIP To affect ventilation, adjust: –Respiratory Rate –Tidal Volume PIP

22. Compliance The relative ease with which a structure distends (distensibility) Pulmonary physiology uses the term compliance to describe the elastic forces that oppose lung inflation (lung tissue and surrounding thoracic structures) The change in volume that corresponds to a change in pressure Compliance = V / P

23. Resistance Frictional forces associated with ventilation are the result of the anatomical structure of the conductive airways. With higher airway resistance, more of the pressure for breathing goes to the airways and not the alveoli; consequently, a smaller volume of gas is available for gas exchange

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25. Other Modes of ventilation Pressure- regulated volume control (PRVC) Volume support Inverse ratio (IRV) Airway- pressure release ventilation (APRV) Bi- level CPAP High- frequency

26. Criteria to be met before initiating weaning (CALMS) 39 Alert mental status Good cough and gag reflexes Lack of upper airway edema and obstruction Adequate oxygenation/ventilation Absence of Neuromuscular Weakness CNS: Airway: Lungs: Muscles: Quality/Quantity Frequency of suctioning Secretions:

27. 41 Spontaneous breathing trial (SBT) SBT to assess extubation readiness 30-120 minutes trials If tolerated, patient can be extubated CPAP T- Piece Low SIMV

28. Prevention/treatment of upper airway edema Steroids Epinephrine nebs Cold saline

29. Precautions Before Extubation Keep NPO For 4 hours Gastric decompression Airway suctioning ET Cuff Deflation Prop Up the Patient

30. Signs of SBT failure 42 Change in mental status Coma/somnolence Agitation/Anxiety Signs of increased work of breathing Nasal flaring Tachypnea and low tidal volume Paradoxical breathing movements Use of accessory respiratory muscles Hemodynamic instability Tachycardia Hypotension

31. Treat the patient not the labs. The science of mechanical ventilation is to optimize gas exchange, The art is to achieve that without damaging the lung Once daily trial of SBT is the most effective way of determining readiness for extubation Take Home Message