Basic Modes of ventilators


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Basic Modes of ventilators

  1. 1. Modes of Ventilators Dr Farhan Shaikh Consultant Pediatric Intensivist Rainbow Children’s Hospital, Hyderabad
  2. 2. “ MODE” <ul><li>The breath type and pattern of breath delivery during a mechanical ventilation constitutes the “mode” of ventilation </li></ul>
  3. 3. Basic Ventilator Design In a SERVO ventilator.. Neonatal mode- peak flow 13L/min max Vt 39ml Pediatric mode- Peak flow 33L/min max Vt 399ml Adult mode- Peak flow 200L/min max Vt 3999ml
  4. 4. Based on “Type of breath” <ul><ul><ul><ul><li>Controlled modes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>“ Assisted” modes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Spontaneous modes </li></ul></ul></ul></ul>
  5. 5. Control Modes <ul><li>Ventilatror delivers a breath, the “Pre-set” parameters are.. </li></ul><ul><li>Inspiratory time (Ti) </li></ul><ul><li>Pressure (in PC mode) </li></ul><ul><li>Tidal Volume (In VC mode) </li></ul>If the child has spontaneous breath, the ventilator will Not adjust its parameters of Ti, Pressures or delivered Vt, based on the child’s requirement
  6. 6. <ul><ul><ul><li>Spontaneous Mode: </li></ul></ul></ul><ul><ul><ul><li>Patients can breathe spontaneously through a ventilator circuit; sometimes called T-Piece Method because it mimics having the patient ET tube connected to a Briggs adapter (T-piece) </li></ul></ul></ul><ul><ul><ul><li>ASSISTED MODES : </li></ul></ul></ul><ul><ul><ul><li>Ventilator responds to patient’s efforts and delivers </li></ul></ul></ul><ul><ul><ul><li>a support breath, adjusting or augmenting pressure </li></ul></ul></ul><ul><ul><ul><li>or volume. </li></ul></ul></ul>
  7. 7. Triggering <ul><li>The factor which initiates a mechanical breath from the ventilator is called a “trigger” </li></ul><ul><li>Time triggering </li></ul><ul><li>Patient triggering </li></ul>
  8. 8. When the Expiratory time ends, the ventilator automatically starts delivering the next breath. Thus each breath is “triggered” by time. Hence known as “Time triggered” TIME TRIGGERING
  9. 9. Concept of asynchrony
  10. 10. Ventilator delivers breaths at Pre-set rates and Pressures/ volumes Patient breaths Spontaneously in between the Ventilator breaths ASYNCHRONY
  11. 11. Effects of Asynchrony <ul><li>Impaired gas exchange </li></ul><ul><li>Air trapping , pneumothorax </li></ul><ul><li>Altered cerebral circulation in preterm neonates associated with increased incidance of intraventricular hemorrhages </li></ul>
  12. 12. <ul><li>Asynchrony can be avoided if the ventilator is able to “sense” initiation and desirably even termination of the patients breathing efforts. </li></ul>
  13. 13. Types of signal detection <ul><li>Abdominal motion by applanation transducer(Infant Star) </li></ul><ul><li>Thoracic impedance by electronic leads on chest wall. (Sechrist) </li></ul><ul><li>Airway Flow : </li></ul><ul><li>A-Hot wire anonemeters (Draeger babylog) </li></ul><ul><li>B- Pneumotachograph (vodpt in Seimens 300A) </li></ul><ul><li>Airway pressures: </li></ul><ul><li>Changes in airway pressure. (Neoport) </li></ul>
  14. 14. Limitation of the delivered breath <ul><li>A breath initiated by the ventilator can be “limited” by achievement of .. </li></ul><ul><li>Desired pressure – Pressure limited or Pressure controlled </li></ul><ul><li>Desired Volume- Volume limited or Volume Control </li></ul>
  15. 15. PC Vs VC modes CMV- PC mode CMV- VC mode Pressure is set Delivered Vt changes according to lung compliance When the child is spontaneously breathing, as the PIP is fixed, it will reduce patient discomfort Volume is set Delivered PIP will vary based on pulmonary compliance and airway resistance When child is spontaneoulsy breathing, since PIP is variable, it will rise during asynchrony leading to increased WOB and discomfort
  16. 16. PC Vs VC Mode PIP Pplateu Pressure plateu PEEP PEEP PC MODE VC MODE In PC mode if the Ti is increased, the pressure plateau is sustained and a continuous distending pressure can be applied over the alveoli through out the Inspiration
  17. 17. PC Vs VC Mode PC Mode VC Mode Decelerating Flow Constant flow
  18. 18. The verdict <ul><li>Divided opinions from various recent clinical studies. </li></ul><ul><li>If the child does not have spontaneous breathing, both PC and VC modes are equally beneficial in children particularly if the VC mode also utilizes decelerating flow pattern. </li></ul><ul><li>Campbell RS,Davis BR: Pressure-control versus Volume-controled ventilation: does it really matter? Resp Care 47:416,2002 </li></ul>
  19. 19. <ul><li>In children with spontaneous breathing, PC mode may lower the work of breathing, and comfort, thus reducing need for sedation and paralysis as compared to the VC modes. </li></ul><ul><li>Individual comfort zones and institutional practices are also important </li></ul><ul><li>Campbell RS,Davis BR: Pressure-control versus Volume-controled ventilation: does it really matter? Resp Care 47:416,2002 </li></ul>
  20. 20. Termination of the Inspiratory phase (cycling) <ul><li>Volume Cycled Ventilation: </li></ul><ul><li>Inspiration is terminated after the delivery of set Vt </li></ul><ul><li>Most of the ventilators do not use volume displacement devices, hence most of ventilators do not have Volume cycling except Puritan Bennet 740 and 760 </li></ul>
  21. 21. <ul><li>Time Cycled: </li></ul><ul><li>When the inspiratory phase ends after predetermined time has elapsed. </li></ul><ul><li>e.g. Servo, Draeger Evita and Hamilton Galilio </li></ul>
  22. 22. Flow Cycling <ul><li>Ventilator ends inspiration and enters into expiratory phase, once the flow has decreased to a predetermined value during inspiration </li></ul><ul><li>In SERVO it is fixed at 5% </li></ul>In newer ventilators (Hamilton Galilio) the flow termination percentage can be adjusted from 5% to 75%. Cairo JM,PilbeamSP:Mosby’s respiratory care equipment,ed7,St Louis,2004,Mosby Flow TS 5% Flow cycling Peak flow (100%)
  23. 23. Assist Control (A/C) mode <ul><li>Upper Graph is patient’s efforts and lower is ventilator breathes </li></ul><ul><li>Each of patient’s effort that meets the threshold, results in full Ventilatory Breath. </li></ul><ul><li>Assist control mode is flow (or volume) controlled and time cycled mode </li></ul><ul><li>Fixed Ti, Flow and Vt means expiratory asynchrony as the inspiratory times of patient and ventilator may differ. </li></ul>
  24. 24. Flow cycling Or termination sensitivity “ Flow Cycling”
  25. 25. A/C+ termination sensitivity <ul><li>prevents “air trapping” during rapid breathes </li></ul><ul><li>ensures adequate inspiratory time if infants breaths slowly </li></ul>
  26. 26. <ul><ul><ul><li>Indications </li></ul></ul></ul><ul><ul><ul><ul><li>Patients requiring full ventilatory support with stable respiratory drive </li></ul></ul></ul></ul><ul><ul><ul><li>Advantages </li></ul></ul></ul><ul><ul><ul><ul><li>Decreases the work of breathing (WOB) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Allows patients to regulate respiratory rate </li></ul></ul></ul></ul><ul><ul><ul><li>Complications </li></ul></ul></ul><ul><ul><ul><ul><li>Alveolar hyperventilation </li></ul></ul></ul></ul>CMV-ASSIST/CONTROL
  27. 27. Concept of IMV
  28. 28. IPPV or CMV mode <ul><li>There is no flow supplied from the ventilator to the patient efforts during patient’s spontaneous breaths </li></ul>
  29. 29. IMV <ul><li>Continuous flow of gas even during expiration. </li></ul><ul><li>This combination of mechanical and spontaneous breathing under a continuous gas flow was called Intermittent Mandatory Ventilation ” </li></ul><ul><li>i.e. IMV </li></ul>
  30. 30. Summary of “Control modes” <ul><li>The breathe can be initiated as .. </li></ul><ul><li>“ time triggered” or “patient triggered” </li></ul><ul><li>It can be pressure limited or Volume limited </li></ul><ul><li>It can be time cycled or flow cycled </li></ul>
  31. 31. <ul><li>In CMV , the child, during his/her spontaneous breathing efforts does not receive continuous flow of oxygen or air </li></ul><ul><li>In IMV , the ventilator provides flow of Oxygen or air when the child has spontaneous breathes, but does not “support” any breath </li></ul>
  32. 32. Uses of - Control modes <ul><ul><ul><li>Appropriate when a patient can make no effort to breathe or when ventilation must be completely controlled </li></ul></ul></ul><ul><ul><ul><ul><li>Cerebral malfunctions </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Spinal cord injury </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Phrenic nerve injury </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Motor nerve paralysis </li></ul></ul></ul></ul>
  33. 33. <ul><ul><ul><li>The patient can breath spontaneously, but is sedated or paralyzed with medications .. </li></ul></ul></ul><ul><ul><ul><ul><li>Seizure activity </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tetanic contractions </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Inverses I:E ratio ventilation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Crushed chest injury – stabilizes the chest </li></ul></ul></ul></ul>Use of Control modes
  34. 34. Problem of “stacking” in IMV mode <ul><ul><ul><li>Mechanical rate and spontaneous rate may asynchronous causing “stacking” </li></ul></ul></ul><ul><ul><ul><ul><ul><li>May cause barotrauma or volutrauma </li></ul></ul></ul></ul></ul>
  35. 35. Assisted modes <ul><li>The Ventilator will sense and initiate a breath to the patient, however it will not be just a mandatory breath of fixed parameters, </li></ul><ul><li>The “assisted” breaths will alter its Ti, or pressure or volume delivery based on the requirement of the child. </li></ul>
  36. 36. Synchronized IMV <ul><ul><ul><li>Originally designed to tackle the problem of “breath stacking” </li></ul></ul></ul><ul><ul><ul><li>At a predetermined interval (respiratory rate), which is set by the operator, the ventilator waits for the patient’s next inspiratory effort </li></ul></ul></ul><ul><ul><ul><li>When the ventilator senses the effort, the ventilator assists the patient by synchronously delivering a mandatory breath </li></ul></ul></ul>SIMV
  37. 37. <ul><ul><ul><li>If the patient fails to initiate ventilation within a predetermined interval, in SIMV mode, the ventilator provides a mandatory breath at the end of the time period </li></ul></ul></ul>
  38. 38. <ul><li>SIMV </li></ul><ul><ul><ul><li>Indications </li></ul></ul></ul><ul><ul><ul><ul><li>Facilitate transition from full ventilatory support to partial support and eventually “weaning” </li></ul></ul></ul></ul><ul><ul><ul><li>Advantages </li></ul></ul></ul><ul><ul><ul><ul><li>As all the spontaneous breathes are not supported, only the mandatory breathes are synchronised with the patient’s triggers and rest of the time the patient is spontaneously breathing without any “support”,it will maintain respiratory muscle strength by avoiding muscle atrophy </li></ul></ul></ul></ul>
  39. 39. <ul><ul><li>Three basic means of providing support for continuous spontaneous breathing during mechanical ventilation </li></ul></ul><ul><ul><ul><li>Spontaneous breathing </li></ul></ul></ul><ul><ul><ul><li>CPAP </li></ul></ul></ul><ul><ul><ul><li>PSV – Pressure Support Ventilation </li></ul></ul></ul>Spontaneous Modes
  40. 40. Spontaneous Modes <ul><ul><ul><li>Patients can breathe spontaneously through a ventilator circuit; sometimes called T-Piece Method because it mimics having the patient ET tube connected to a Briggs adapter (T-piece) </li></ul></ul></ul><ul><ul><ul><li>Advantage </li></ul></ul></ul><ul><ul><ul><ul><li>Ventilator can monitor the patient’s breathing and activate an alarm if something undesirable occurs </li></ul></ul></ul></ul>
  41. 41. Pressure Support (PSV) Mode <ul><li>Patient Triggered, Pressure limited and Flow cycled mode. </li></ul><ul><li>Thus decelerating flow pattern will be delivered. </li></ul><ul><li>Can be used independently or along with SIMV </li></ul>
  42. 42. <ul><li>The operator sets an inspiratory ventilator pressure limit and a maximum inspiratory time limit. </li></ul><ul><li>The support or “limit” is the pressure above PEEP set by the operator, usually 50% of the difference between PIP and PEEP of an SIMV breath </li></ul>SIMV + PS
  43. 43. <ul><li>How much of “pressure support” is appropriate? </li></ul><ul><li>3 to 3.5 mm: 10cmH2O (above PEEP) </li></ul><ul><li>4 to 4.5 mm: 8 cmH2O (above PEEP) </li></ul><ul><li>5 mm or larger : 6 cm H2O (above PEEP) </li></ul><ul><li>Generally “support” is determined by watching the delivered Vt, and minimizing asynchrony </li></ul>
  44. 44. <ul><li>When PS mode used alone, during the periods of poor respiratory drive may result in alveolar hypoventilation, hypoxaemia and CO2 retention, unless a back-up ventilation is provided (e.g.SIMV) </li></ul><ul><li>Studies have demonstrated significant advantage of PSV + SIMV combination as “weaning mode” </li></ul><ul><li>Osorio W, Claure N, D’Ugard C, Athavale K, Bancalari E. Effects of pressure support during an acute reduction of synchronized intermittent mandatory ventilation in preterm infants. J Perinatol 2005;25:412–6 . </li></ul>
  45. 45. Concept of Tidal Volume monitoring
  46. 46. <ul><li>Laplaces Law : P=2ST/R </li></ul><ul><li>e.g. </li></ul><ul><li>After surfactant therapy the lung compliance improves and alveolar radius enlarges, this would mean reduced pressure assistance. </li></ul><ul><li>If the ventilator continues to provide same support, it will result in more Vt delivery causing Volutrauma. </li></ul>
  47. 47. DUAL CONTROL MODES <ul><li>Control on both the volume and pressures </li></ul><ul><li>Actually one variable is controlled and the other monitored and regulated </li></ul><ul><li>Almost always it is the pressure which is controlled to attain a specific volume </li></ul><ul><li>Ability to automatically adjust the ventilatory support according to the patient’s changes in respiratory mechanics and ventilatory demand is called “closed loop” system </li></ul>
  48. 48. PRVC <ul><li>A form of closed loop ventilation combining features of volume control and pressure control modes. </li></ul><ul><li>Clinician-set parameters are max pressure, target Vt, rate, Ti, PEEP and FiO2 </li></ul>
  49. 49. PRVC <ul><li>Ventilator first delivers 5cmH2O of pressure support for initial few breaths and calculates patient’s dynamic compliance. </li></ul><ul><li>Subsequently, with each breath provides pre determined Vt at lowest possible pressure support. </li></ul>
  50. 50. PRVC <ul><li>As it is time cycled and not flow cycled, there is no termination sensitivity hence not useful as “weaning mode”. </li></ul><ul><li>As it utilizes decelerating flow pattern, it is useful in conditions like ARDS,Bronchopneumonia etc where there are some areas with atelectasis and some areas with hyperinflation. </li></ul>
  51. 51. Volume Support <ul><li>Patient triggered, pressure limited flow cycled mode </li></ul><ul><li>Hybrid of PSV and PRVC </li></ul><ul><li>Vt is pre determined. This predetermined Vt is achieved by adjusting pressure support (closed loop system) </li></ul><ul><li>Since it is flow cycled , expiratory asynchrony is minimized and is useful in spontaneously breathing patient </li></ul>
  52. 52. Volume Guaranteed (VG) Pressure Limited <ul><li>Target Vt is delivered by increasing or decreasing the Pressure. </li></ul><ul><li>It is different from other volume control modes by the fact that the expiratory Vt is measured for calculations </li></ul>
  53. 53. SUMMING Up! <ul><li>A- Types of breathes: </li></ul><ul><li>Mandatory breathes: (breath delivered at set rate) </li></ul><ul><li>CMV/IMV </li></ul><ul><li>(both can be time triggered (control modes) </li></ul><ul><li>Or patient triggered (Assist control) </li></ul><ul><li>Support Breathes: SIMV, (Ventilator synchronises its mandatory breathes with patients efforts), PSV, VS </li></ul><ul><li>Spontaneous breathes: CPAP,PSV </li></ul>
  54. 54. <ul><li>B- Limit Variables: </li></ul><ul><li>Single variable: PC, VC </li></ul><ul><li>Dual variable: PRVC,VAPS,VG </li></ul><ul><li>C- Cycling Variables: Time Cycling, Flow cycling, </li></ul><ul><li>Volume cycling </li></ul>
  55. 55. THANK YOU
  56. 58. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>CPAP </li></ul></ul><ul><ul><ul><li>Ventilators can provide CPAP for spontaneously breathing patients </li></ul></ul></ul><ul><ul><ul><ul><li>Helpful for improving oxygenation in patients with refractory hypoxemia and a low FRC </li></ul></ul></ul></ul><ul><ul><ul><ul><li>CPAP setting is adjusted to provide the best oxygenation with the lowest positive pressure and the lowest FiO2 </li></ul></ul></ul></ul>
  57. 59. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>CPAP </li></ul></ul><ul><ul><ul><li>Advantages </li></ul></ul></ul><ul><ul><ul><ul><li>Ventilator can monitor the patient’s breathing and activate an alarm if something undesirable occurs </li></ul></ul></ul></ul>
  58. 60. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PEEP (Positive End Expiratory Pressure) </li></ul></ul><ul><ul><ul><li>“ According to its purest definition, the term PEEP is defined as positive pressure at the end of exhalation during either spontaneous breathing or mechanical ventilation. However, use of the term commonly implies that the patient is also receiving mandatory breaths from a ventilator.” (Pilbeam) </li></ul></ul></ul><ul><ul><ul><li>PEEP becomes the baseline variable during mechanical ventilation </li></ul></ul></ul>
  59. 61. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PEEP </li></ul></ul><ul><ul><ul><li>Helps prevent early airway closure and alveolar collapse and the end of expiration by increasing (and normalizing) the functional residual capacity (FRC) of the lungs </li></ul></ul></ul><ul><ul><ul><li>Facilitates better oxygenation </li></ul></ul></ul><ul><ul><ul><li>NOTE: PEEP is intended to improve oxygenation, not to provide ventilation, which is the movement of air into the lungs followed by exhalation </li></ul></ul></ul>
  60. 62. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>Pressure Support Ventilation – PSV </li></ul></ul><ul><ul><ul><li>Patient triggered, pressure targeted, flow cycled mode of ventilation </li></ul></ul></ul><ul><ul><ul><li>Requires a patient with a consistent spontaneous respiratory pattern </li></ul></ul></ul><ul><ul><ul><li>The ventilator provides a constant pressure during inspiration once it senses that the patient has made an inspiratory effort </li></ul></ul></ul>
  61. 63. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul>
  62. 64. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>Indications </li></ul></ul></ul><ul><ul><ul><ul><li>Spontaneously breathing patients who require additional ventilatory support to help overcome </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li> WOB,  C L ,  Raw </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Respiratory muscle weakness </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Weaning (either by itself or in combination with SIMV) </li></ul></ul></ul></ul>
  63. 65. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>Advantages </li></ul></ul></ul><ul><ul><ul><ul><li>Full to partial ventilatory support </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Augments the patients spontaneous V T </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Decreases the patient’s spontaneous respiratory rate </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Decreases patient WOB by overcoming the resistance of the artificial airway, vent circuit and demand valves </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Allows patient control of T I , I , f and V T </li></ul></ul></ul></ul>
  64. 66. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>Advantages </li></ul></ul></ul><ul><ul><ul><ul><li>Set peak pressure </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Prevents respiratory muscle atrophy </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Facilitates weaning </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Improves patient comfort and reduces need for sedation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>May be applied in any mode that allows spontaneous breathing, e.g., VC-SIMV, PC-SIMV </li></ul></ul></ul></ul>
  65. 67. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>Disadvantages </li></ul></ul></ul><ul><ul><ul><ul><li>Requires consistent spontaneous ventilation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Patients in stand-alone mode should have back-up ventilation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>VT variable and dependant on lung characteristics and synchrony </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Low exhaled E </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fatigue and tachypnea if PS level is set too low </li></ul></ul></ul></ul>
  66. 68. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>Flow Cycling During PSV </li></ul></ul><ul><ul><ul><li>Flow cycling occurs when the ventilator detects a decreasing flow, which represents the end of inspiration </li></ul></ul></ul><ul><ul><ul><li>This point is a percentage of peak flow measured during inspiration </li></ul></ul></ul><ul><ul><ul><ul><li>PB 7200 – 5 L/min </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Bear 1000 – 25% of peak flow </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Servo 300 – 5% of peak flow </li></ul></ul></ul></ul><ul><ul><ul><li>No single flow-cycle percent is right for all patients </li></ul></ul></ul>
  67. 69. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>Flow Cycling During PSV </li></ul></ul><ul><ul><ul><li>Effect of changes in termination flow </li></ul></ul></ul><ul><ul><ul><li>A: Low percentage (17%) </li></ul></ul></ul><ul><ul><ul><li>B: High percentage (57%) </li></ul></ul></ul><ul><ul><ul><li>Newer ventilators have an adjustable flow cycle criterion, which can range from 1% - 80%, depending on the ventilator </li></ul></ul></ul>
  68. 70. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV during SIMV </li></ul></ul><ul><ul><ul><li>Spontaneous breaths during SIMV can be supported with PSV (reduces the WOB) </li></ul></ul></ul>PCV – SIMV with PSV
  69. 71. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV during SIMV </li></ul></ul><ul><ul><ul><li>Spontaneous breaths during SIMV can be supported with PSV </li></ul></ul></ul>VC – SIMV with PSV
  70. 72. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>NOTE: During pressure support ventilation (PSV), inspiration ends if the inspiratory time (T I ) exceeds a certain value. This most often occurs with a leak in the circuit. For example, a deflated cuff causes a large leak. The flow through the circuit might never drop to the flow cycle criterion required by the ventilator. Therefore, inspiratory flow, if not stopped would continue indefinitely. For this reason, all ventilators that provide pressure support also have a maximum inspiratory time. </li></ul></ul></ul>
  71. 73. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV </li></ul></ul><ul><ul><ul><li>Setting the Level of Pressure Support </li></ul></ul></ul><ul><ul><ul><ul><li>Goal: To provide ventilatory support </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Spontaneous tidal volume is 10 – 12 mL/Kg of ideal body weight </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Maintain spontaneous respiratory rate <25/min </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Goal: To overcome system resistance (ET Tube, circuit, etc.) in the spontaneous or IMV/SIMV mode </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Set pressure at (PIP – P plateau) achieved in a volume breath or at 5 – 10 cm H2O </li></ul></ul></ul></ul></ul>
  72. 74. Modes of Ventilation <ul><li>Spontaneous Modes </li></ul><ul><ul><li>PSV - The results of your work </li></ul></ul>35 cm H2O 10 cm H2O