1 / 80

MECHANICAL VENTILATION

MECHANICAL VENTILATION. Phunsup Wongsurakiat, MD, FCCP Division of Respiratory Disease and TB Department of Medicine, Siriraj Hospital. Mechanical Ventilation. Invasive (intubation) Non-invasive (other interface such as face mask): - negative pressure

duane
Télécharger la présentation

MECHANICAL VENTILATION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MECHANICAL VENTILATION • Phunsup Wongsurakiat, MD, FCCP • Division of Respiratory Disease and TB • Department of Medicine, Siriraj Hospital

  2. Mechanical Ventilation • Invasive (intubation) • Non-invasive (other interface such as face mask): • - negative pressure • - positive pressure

  3. DISTENDING PRESSURES Plat P - Base P (PEEP) = pressure to distend resp system (lung + chest wall) Plat P = peak alveolar pressure Transpulmonary pressure = Plat P – Pleural pressure

  4. Influence of chest wall stiffness 35 cm H2O 35 cm H2O 5 cm H2O 10 cm H2O 30 cm H2O 25 cm H2O

  5. FLOW Resistance (R) Peak P - PlatP = pressure for flow R = Flow/(PeakP - Plat P)

  6. Physiology of Respiration • O2 consumption (VO2) ≈ 250 mL/ min • CO2 production (VCO2) ≈ 200 mL/ min • Cardiac output (CO) ≈ 5 L/min • Minute ventilation = RR X VT ≈ 5 - 8 L/min • VT ≈ 5 - 8 mL / kg • RR ≈ 12 - 20 bpm • PaCO2 = 35-45 mmHg • pH = 7.35-7.45

  7. Physiology of Respiration • PAO2 = PIO2 –PaCO2 / R [PIO2 = FIO2 x (barometric pressure – 47)] • PaCO2 = k x VCO2 / VA

  8. Mechanical Ventilation • Variables • Mode • Objectives • Clinical settings • Complications

  9. Mechanical VentilationVariables • Tidal volume • Rate • Total time (inversely related to rate): - inspiratory time (adjustable) - expiratory time (total time - inspiratory time) • Flow (tidal volume / inspiratory time) • Minute ventilation

  10. Mechanical VentilationVariables • Trigger sensitivity • FiO2 • Pressure: - peak pressure - plateau pressure • Compliance

  11. Mechanical VentilationModes Limit • variables rise no higher than some preset value and increase to preset value before inspiration ends = limit variable Cycle • Variable that terminate inspiration = cycle variable

  12. Breath characteristicsGas Delivery

  13. Mechanical Ventilation Bird • Limit: pressure, flow • Cycle: pressure Bennett 7200 (volume assist-control) • Limit: volume, flow • Cycle: volume Pressure support • Limit: pressure • Cycle: flow

  14. Mechanical VentilationModes • Volume-targeted: Pre-set tidal volume • Pressure-targeted: Pre-set inspiratory pressure • Mandatory breaths: Breaths that the ventilator delivers to the patient at a set frequency, volume/pressure, flow/time • Spontaneous breaths: Patient initiated breath

  15. Mechanical VentilationModes Volume-targeted • Controlled mechanical ventilation (CMV) • Assist/control (A/C) mechanical ventilation • Synchronized intermittent mandatory ventilation (SIMV)

  16. Modes of Ventilation (CMV) • Background: • Full preset tidal volume at a fixed preset rate • Rate and minute ventilation cannot  by patient effort • Trigger sensitivity is locked out, need sedated or paralyzed

  17. Modes of Ventilation (CMV) Advantages: • Near complete resting of ventilatory muscles • Respiratory muscle rest, secured minute ventilation Disadvantages: • “Stack" breaths (air trapping) and develop barotrauma • “AutoPEEP" with barotrauma or hypotension • Need sedated or paralyzed • Respiratory muscle atrophy Uses: • apnea, little breathing effort, unstable

  18. Modes of Ventilation (Assist/Control) • Background: • Full preset tidal volume at a minimum preset rate • Additional full tidal volumes given if the patient initiates extra breaths

  19. Modes of Ventilation (Assist/Control) • Advantages: • Near complete resting of ventilatory muscles • Comfortable, respiratory muscle rest, secured minute ventilation • Effectively used in awake, sedated, or paralyzed patients • Disadvantages: • Hyperventilate and become alkalotic • “Stack" breaths (air trapping) and develop barotrauma • “AutoPEEP" with barotrauma or hypotension • Uses: • apnea, little breathing effort, unstable

  20. Modes of Ventilation (SIMV + Pressure support) • Background: • Preset tidal volume at a fixed preset rate • Ventilator waits a predetermined trigger period • Patient can take additional breaths but tidal volume of these extra breaths is dependent on the patient's inspiratory effort

  21. Modes of Ventilation (SIMV + Pressure support) • Advantages: • Improved venous return: intermittent negative pressure (spontaneous) breaths • More comfortable: more control over their ventilatory pattern and minute ventilation Disadvantages: • Can result in chronic respiratory fatigue if set rate is too low; • Uses: • Weaning, bronchopleural fistula

  22. Mechanical VentilationModes Pressure-targeted • Pressure support ventilation (PSV) • Pressure-control ventilation (PCV) • Pressure-targeted assist-control (A/C-PC) • Pressure-targeted SIMV (SIMV-PC)

  23. Pressure support Ventilation • Background: • Patient triggers, a preset pressure support is delivered • Terminate inspiration by flow rate • Tidal volume and minute ventilation are dependent on the preset pressure • and patient’s lung-thorax compliance

  24. Pressure support Ventilation • Advantages: • Avoids patient-ventilator asynchrony • More comfortable: full control over ventilatory pattern and minute ventilation • Avoids breath stacking and autoPEEP (especially in patients with COPD) • Disadvantages: • Required patient’s triggering, cannot be used in heavily sedated, paralyzed, or comatose patients • Respiratory muscle fatigue if pressure support is set too low

  25. Pressure Control Ventilation • Background: • Ventilator control predetermined pressure in a • fixed predetermined time and rate

  26. Pressure Control Ventilation • Advantages: • Pressure and time are controlled • High flow rate • Disadvantages: • Tidal volume variable • Produced autoPEEP if inspiratory time too long • Uncomfortable mode for most patients

  27. Pressure-targeted assist-control (A/C-PC) • All breaths machine-delivered at a preset inflation pressure • Patients can  rate by triggering additional machine breaths if desired • Same as assist/control volume targeted mode

  28. Pressure-targeted SIMV(SIMV-PC) • Fixed rate of machine-delivered breaths at a preset inflation pressure • Patients can breathe spontaneously between machine-delivered breaths if desired • Same as SIMV volume targeted mode

  29. Mechanical Ventilation • Objectives: • Physiology • Comfortable • Least complications

  30. Mechanical Ventilation • Usual settings • Minute Ventilation = RR X VT ( 5 - 8 L/min) • VT = 5 - 8 mL / kg • RR = 12 - 20 bpm • PaCO2 = 35-45 mmHg • pH = 7.35-7.45

  31. Mechanical Ventilation • Triggering: sensitivity of ventilator to patient’s respiratory effort. • Flow or pressure setting that allows ventilator to detect patient’s inspiratory effort • Allows ventilator synchronize with patient’s spontaneous respiratory efforts • Improving patient’s comfort during mechanical ventilation. • Setting: lowest but not self cycling • Less work in flow triggering

  32. Mechanical Ventilation • Flow rate: • adjust to patient’s comfort • Usually > 60 L/min • Pressure: • Plateau pressure < 30 cmH2O

  33. Positive End Expiratory Pressure(PEEP) •  Functional residual capacity • Move fluid from alveoli into interstitial space • Improve oxygenation

More Related