Mechanical Ventilation

1. Mechanical Ventilation The Basics M.RADHA KRISHNAN BPT,PGDRT,PGDRCM SENIOR RESPIRATORY THERAPIST(ICU) KMCH COIMBATORE.

2. Mechanical VentilationBasic concepts • Introduction • Indications • Modes • Initial Settings

3. Basic Physiology • Transairway pressure Gradient • Gradient between mouth opening pressure (Pao)and Alveolar pressure (PA)

5. Basic Physiology

6. Negative pressure ventilation • Pre = Pao (Zero) - Palv (Negative)

7. Positive pressure ventilation • Prs = Pao (+ve) - Palv (0)

8. Basic Physiology

9. Delicate balance between Load and Capacity Depressed Respiratory Drive Drug brain Stem Increased Minute Ventilation Pain, Anxiety, Excessive Feeding Sepsis Increased VD/VT Muscular Disorders Myasthenia Gravis Electrolyte Disorders Prolonged Neuromuscular blockade Increased Elastic Loads Low Lung Compliance Low Thoracic Compliance Intrinsic PEEP Loads Capacity Thoracic Wall abnormality Increased Resistive Loads Airway Obstruction Neuromuscular disorder

10. Respiratory Failure

11. WHAT IS A VENTILATOR? • Any machine used to PUSH Gas mixture (air & O2) in to the lungs. This can be done by applying positive pressure at the airway either Invasively or Non invasively.

13. Classification of mechanical ventilators

14. Origins of mechanical ventilation The era of intensive care medicine began with positive-pressure ventilation • Negative-pressure ventilators (“iron lungs”) • Non-invasive ventilation first used in Boston Children’s Hospital in 1928 • Used extensively during polio outbreaks in 1940s – 1950s • Positive-pressure ventilators • Invasive ventilation first used at Massachusetts General Hospital in 1955 • Now the modern standard of mechanical ventilation The iron lung created negative pressure in abdomen as well as the chest, decreasing cardiac output. Iron lung polio ward at Rancho Los Amigos Hospital in 1953.

15. Indications – simplified • Respiratory • Restrictive • ARDS • ILD • Obstructive • Bronchial asthma • COPD • Central airway obstruction • Non respiratory • Restrictive • Chest wall • Cardiac • Normal • Airway protection • Respiratory drive dysfunction

16. Mechanical Parameters Predicting Impending Failure

17. Modes • CMV (Controlled Mandatory ventilation) • ACMV • IMV • Synchronized intermittent mandatory ventilation • CPAP • PS(Pressure support ventilation)

18. Mechanical VentilationBasic Concepts • Introduction • Indications • Modes • Initial Settings

19. VOLUME CONTROL • Normal emphysema ARDS alveoli

20. VOLUME CONTROL

21. Pressure Control ventilation

22. Common Modes • CMV (Control Mode Ventilation) • ACMV (Assist Control Mandatory Ventilation) • IMV (Intermittent Mandatory Ventilation) • SIMV (Synchronized Intermittent Mandatory Ventilation) • PSV (Pressure Support Ventilation )

23. CMV

24. CMV Control Mode Ventilation • Every breath is mandatory and ventilator triggered with no spontaneous breaths • Mandatory breaths at a set frequency and tidal volume delivered to the patient • The inspiratory valve is closed to the patient otherwise so that no additional breaths can be taken

25. ACMV

26. ACMV

27. IMV, volume-limited Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB, Scmidt GA, & Wood LDH(eds.): Principles of Critical Care

28. IMV • TYPE OF BREATH : ASSIST & CONTROL • TRIGGERING : ASSIST & CONTROL • CYCLING : VOLUME CYCLED • COMPLCATION: BREATH STACKING

29. SIMV, volume-limited Ingento EP & Drazen J: Mechanical Ventilators, in Hall JB, Scmidt GA, & Wood LDH(eds.): Principles of Critical Care

30. CPAP level CPAP Flow (L/m) Pressure (cm H2O) Volume (mL) Time (sec)

31. CPAP • CPAP is PEEP is applied to the airway of a patient who is breathing spontaneously

32. Flow Cycling Set PS level PSV Patient Triggered, Flow Cycled, Pressure limited Mode Flow (L/m) Pressure (cm H2O) Volume (mL) Time (sec)

33. PRESSURE SUPPORT VENTILATION • Î Spontaneous Tidal Volume • Reduces RR • Reduces WOB

34. Initial Settings • Mode- ACMV • Tidal volume : 7 to 8 ml/kg COPD 6ml/kg & ARDS 5 to 6 ml/kg • Fio2 100% or 60% • RR NORMAL 16 to 18 b/m • PEEP 5 CMH2O • I:E RATIO 1:2 , COPD 1:4 • PIF 60L/MIN • VC Monitor PIP & plateau , PC Monitor Tidal volume & Minute ventilation

35. Recapitulation Spont. Breath Mandatory Breath

36. SCALARS Flow/Time Pressure/Time Volume/Time

37. LOOPS Pressure-Volume Flow-Volume

38. Spontaneous Breath Inspiration Time (sec) Flow (L/min) Expiration

39. Mechanical Breath Inspiration Time (sec) Flow (L/min) Expiration

40. Inspiratory Tidal Volume Volume vs Time Volume (ml) Inspiration Expiration TI Time (sec)

41. PIP } Transairway Pressure (PTA) Exhalation Valve Opens Paw (cm H2O) Expiration Time (sec) Begin Expiration Begin Inspiration Inflation Hold (seconds) Pplateau (Palveolar Paw (cm H2O) Time (sec) PIP Airway Resistance Distending (Alveolar) Pressure Expiration Begin Inspiration Begin Expiration

42. Total cycle time TCT Inspiratory Flow Pattern Beginning of expiration exhalation valve opens Peak inspiratory flow rate PIFR Inspiration Expiratory Time TE Insp. time TI Flow (L/min) Time (sec) Beginning of inspiration exhalation valve closes Expiration

43. Beginning of expiration exhalation valve opens Duration of expiratory flow Peak Expiratory Flow Rate PEFR Expiratory Flow Pattern Inspiration Expiratory time TE Time (sec) Flow (L/min) Expiration

44. Components of Pressure-Volume Loop VT Expiration Volume (mL) Inspiration PIP Paw (cm H2O)

45. Flow-Volume Loop Inspiration PIFR Volume (ml) FRC VT Flow (L/min) PEFR Expiration

46. Questions ? Thank you