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Mechanical Ventilation

Mechanical Ventilation. The Basics. M.RADHA KRISHNAN BPT,PGDRT,PGDRCM SENIOR RESPIRATORY THERAPIST(ICU) KMCH COIMBATORE. Mechanical Ventilation Basic concepts. Introduction Indications Modes Initial Settings. Basic Physiology. Transairway pressure Gradient

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Mechanical Ventilation

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  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)

  4. Basic Physiology

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

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

  7. Basic Physiology

  8. 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

  9. Respiratory Failure

  10. 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.

  11. Classification of mechanical ventilators

  12. 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.

  13. 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

  14. Mechanical Parameters Predicting Impending Failure

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

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

  17. VOLUME CONTROL • Normal emphysema ARDS alveoli


  19. Pressure Control ventilation

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

  21. CMV

  22. 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

  23. ACMV

  24. ACMV

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


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

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

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

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

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

  32. 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

  33. Recapitulation Spont. Breath Mandatory Breath

  34. SCALARS Flow/Time Pressure/Time Volume/Time

  35. LOOPS Pressure-Volume Flow-Volume

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

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

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

  39. 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

  40. 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

  41. 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

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

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

  44. Questions ? Thank you

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