Vent modes


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Vent modes

  1. 1. Vent Modes Education and Explanation**Rule #1: Do not touch the vent.**Kindly ask your Respiratory Therapist to make the change for you.
  2. 2. IMV IMV stands for Intermittent Mandatory Ventilation – This mode of ventilation would deliver a breath based entirely on time. » If you set a rate of 12 a breath would be given every 5 seconds regardless of where the patient is in their breathing cycle – This is a mode of ventilation that is no longer used because it can cause over stretching and barotrauma.
  3. 3. IMV (continued) What can be set? – Rate – How often the patient receives a breath – Inspiratory Time/Flow – How quickly the patient receives the ventilator breath. Measured in Sec, or LPM – FiO2 – The Fractional inspired Oxygen from 21% - 100% – Pressure/Volume – The amount of pressure or the volume to be received. » Pressure measured in cmH2O – PEEP – Positive End Expiratory Pressure » Is used to distend the alveoli and thin the alveolar capillary (AC) membrane. » Improves the gas transfer for the oxygen into the capillary system. » Increases a patients functional residual capacity (FRC)
  4. 4. AC/VC Assist Control or Volume Control – Same mode of ventilation with a different name. – Every breath is the same, and a vent breath. – Takes all the work away from the patient. – May be a “first choice” mode of ventilation in other institutions. – Can predispose a patient to atelectasis due to no change in volume. – If: Patient is set at a rate of 12 and a Tidal Volume (Vt) of 500 but breathing 20 times per minute what is the patients Minute Ventilation (MV)?
  5. 5. AC/VC (continued) It would be 10 LPM because every triggered breath is a volume of 500 mL. The set rate is really a “back up” rate. If the patient is sedated the rate of 12 will kick in and the patient will receive a breath every 5 seconds at the desired I time or flow. Have to make sure the I time is adequate for their RR. Can easily become inversed if the patient is tachypneic.
  6. 6. AC/VC (continued) What can be set? – Rate – Inspiratory Time (I time) or Flow LPM – FiO2 – Volume – PEEP
  7. 7. PC Pressure Control – A pressure is set instead of a volume. – Every breath is still the same, and a “back up” rate is set. » Same:  Pressure  I time or Flow – Volume delivered is determined by the patients lung compliance. – Have to make sure the I time is adequate for their RR. Can easily become inversed if the patient is tachypneic.
  8. 8. So, what is lung compliance? Lung compliance is how easily a breath can be pushed into the lung. – Expressed as mL/cmH2O – Can be static or dynamic » Static is preferred What can decrease lung compliance – Bronchospasm – Inflammation – Pulmonary Edema – Mucus – Size of the endotube – Auto-PEEP – Pleural Effusion – Pneumonia – Pneomothorax – Anything that makes it more difficult to push a breath into a patient
  9. 9. SIMV SIMV stands for Synchronized Intermittent Mandatory Ventilation – This mode uses a microprocessor to determine where the patient is in their breathing cycle and will fit the breath at the beginning of inspiration or in-between spontaneous breaths – Much less likely to “stack breaths” and helps encourage comfort on the vent. – Patient will breath spontaneous volumes unassisted by the vent in-between the vent breaths.
  10. 10. SIMV VC What can be set? – Rate – Volume – I time or Flow – FiO2 – PEEP
  11. 11. SIMV PC What can be set? – Rate – Pressure – I time or Flow – FiO2 – PEEP
  12. 12. Now lets add PSV PSV or Pressure Support Ventilation – Is a pressure that augments a patients spontaneous breaths. – Is set as a pressure greater than the baseline PEEP. – Helps the patient overcome the resistance of the endotracheal tube. – Give the patient assistance for the work put in. – Volume of PS breath is completely determined by the patient effort. – Most all “modern” modes of ventilation can have PS. » Ie: SIMV VC + PSV, SIMV PC +PSV, SIMV PRVC + PSV
  13. 13. PRVC Pressure Regulated Volume Control – Combines the best of two modes of ventilation. » Allows the patient to breath in as much flow as they demand…..BUT  Is delivered over a set I time.  Set to a target volume.  Pressure delivered will increase or decrease to lung compliance  Is like having a therapist set the patient’s vent in PC and adjusting the pressure each breath to acheave the target volume.  Every breath is a PRVC breath.
  14. 14. PRVC (continued) Not good for a patient who is breathing a lot spontaneously. – The vent has a difficult time reaching the target volume when the patient’s lung compliance is changing drastically due to spontaneous (negative pressure) breaths. – Works well when a patient’s overall respiratory rate is 20 or less, and their spontaneous volumes are about that of the set volume » Otherwise the patient could be under ventilated compared to set MV
  15. 15. PRVC (continued) At Sparrow hospital it is customary to place patients in SIMV PRVC+PSV. This allows the patients spontaneous breaths to be pressure supported while assuring a specific MV is achieved. – This mode of ventilation is only offered on the newest generation of vents (Servo I and Servo S), and is better than PRVC with assuring the set MV.
  16. 16. Normal Vent Settings Since the ARDS Net Study, hospitals around the country have been setting lower Vt to decrease mortality. – Normal: » Vt = 8-10 cc per Kg of Ideal Body Weight (IBW) » RR = 10-14 breaths per minute » FiO2 = Starts at 100% and weaned to pt tolerance » I time = Usually set by the RT at 1 sec  Increased or decreased based off of graphics and pt comfort / respiratory cycle.
  17. 17. How To Change ABG’s With The Vent To increase PO2 – Increase FiO2 till it is 60% then consider increasing the PEEP. – Increase the PEEP » This will allow for recruitment of alveoli » This will thin the AC membrane » O2 exchange will become easier » Be Aware: Too high of PEEP can cause a decrease in venous return or tamponade the heart (decrease BP)
  18. 18. Changing ABG’s With The Vent (continued) Decrease PCO2 – Increase the rate » Increasing the rate increases the patients MV » Be Aware: Too high of a rate can cause air trapping especially in those with an obstructive lung disease. » Cuts into E time or the amount of time a patient has to exhale. – Increase the Vt. » This increases MV and is only recommended in patients with compliant lungs » Be Aware: Too high of a Vt will cause barotrauma and cytokine release.
  19. 19. HFOV (High Frequency Oscillation Ventilation) This is the simplest mode of ventilation, and it is placed on the sickest patients. Works like a speaker Is the only vent that works off of an active ventilation concept. – All other modes of ventilation we push the breath in and the patient passively exhales. – With the oscillator we push the breath in and pull the breath out with a piston.
  20. 20. HFOV (continued) Works well as an oxygenator, but not so well as a ventilator. Should be considered when a patients FiO2 is greater than 60% on a PEEP greater than 10cm H2O Only 4 things are set and control ventilation. – MAP (works like PEEP and is started 2-4cmH2O greater than that on the ventilator.
  21. 21. HFOV (continued)– FiO2 (amount of inspired O2. Normally set at 100% and weaned down)– The P or d P (this is where ventilation occurs) » Is initially set by increasing till there is jiggling in the mid thigh. (YES REALLY)  This is called the Chest Wiggle Factor (CWF) » Please remember: Only about 20% of the actual pressure set makes it to the alveoli.– And finally the HZ. (1HZ = 60 cycles in a minute) » Is initially set between 3HZ and 6HZ » The Vt is determined by the amount of distance between peaks in the waves.
  22. 22. How To Change Your ABG With HFOV To increase PO2 – Increase the FiO2 – Increase the MAP » This will thin the alveolar wall and make it easier to move the O2 into the capillary system. » Be aware: Just like PEEP, the higher the setting the more likely for a decrease in venous return or tamponade of the heart to occur. (decrease BP)
  23. 23. Changing ABGs with HFOV (continued) To decrease PCO2 – Increase the P » This increases the venilatory pressure. – Decrease the rate » Wait a minute this goes against everything we know! » The oscillator is trapping gas in the lung, by decreasing the HZ we allow more time for CO2 to escape. (this increases the Vt) – As a last ditch the cuff can be deflated some to allow a leak and more CO2 to escape.
  24. 24. Good Luck Remember every patient is different – Just because a mode of ventilation works with most patients does not always make it a fit for all your patients. And lastly – If you have a question, please ask your Respiratory Therapist.
  25. 25. Thank You