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Friday, August 15, 2008

Ventilator extubation Protocol

Perhaps one of the best ways of preventing Ventilator-Associated Pneumonia is by creating and implementing a ventilator extubation protocol. This assures that caregivers begin thinking extubation almost immediately as soon as a person is intubated. Such a protocol my include the following:

1.  Weaning Screen.  In the past physicians wrote orders for weaning parameters, which include respiratory rate, tidal volume (Vt), forced Vital Capacity (FVC), and negative inspiratory pressure (NIF). Most modern protocols call for screening the patient for the following.
  • Fio2 less than 40% 
  • PEEP less than 5 cwp (oxygenation status stable)
  • Heart Rate greater than 50 and less than 120 (heart rate stable)
  • Temperature less than 100.5 (higher means something is not resolved)
  • SpO2 greater than 90% (or specified by physician)
  • Systolic blood pressure greater than 90
  • Minimal or no sedation
  • No signs of respiratory distress
  • Able to follow commands
  • Adequate cough
  • Plateau pressure less than 30 cwp (higher may indicate ARDS)
  • Patient's underlying condition resolved
Please note that these are general recommendations. Some common sense must come into play too, as you must consider the patient. For instance, some patients with chronic lung diseases will have a normal SpO2 less than 90%. So, this must be accounted for when considering whether or not to begin a spontaneous breathing trial (SBT). 

2.  Spontaneous Breathing Trial.  Here is where you place the patient in a spontaneous mode to see how he will do. Some protocols will call for placing the patient in CPAP alone, although others may also involve some pressure support (PS) to accommodate for airway resistance caused by the endotracheal tube (ETT) and the ventilator tubing. Whichever method is used is fine so long as you are consistent. One hospital decided on the following formula:
  • 7.5 ETT or less: Set the patient on CPAP of 5 and PS of 5
  • 8.0 ETT or greater: Set the patient on CPAP of 5 and PS of 0
Basically, you will want to eliminate the resistance of the tubing, although you don't want to set the patient up to fail either. For instance, if you set the PS at 10, the patient has a greater chance of passing the weaning screen, thereby looking good enough to extubate. Yet then require re-intubation later on. 

A good way of knowing where to set the PS if you don't have a protocol is to check the Peak Airway Pressure (PAP) and the Plateau Pressure (P-plat) prior to performing the SBT

Say the Peak pressure for a patient is 20 and the static pressure is 15. The difference between the two is the resistance. Pressure Support, therefore, should be set to equal resistance, which in this case would be five.

If, in our attempt to wean the patient, we turn the pressure support down to zero, then, some experts contend, we are setting the patient up to fail. Therefore, pressure support should never be turned below resistance.

So, that's kind of the thinking on whether or not to use pressure support. Whatever your hospital uses is fine so long as it is consistent. If one therapist is using pressure support and another is not, the values will not be consistent, and therefor will not be very useful.

An SBT entails using a mode like PS and CP, and then seeing how the patient does for about five minutes. Then a second weaning screen should be performed.

  • Respiratory Rate less than 30
  • SpO2 90% or less (or specified by physician)
  • Heart rate less than 120
  • Blood pressure within 20% of baseline
  • RSBI (f/vt) less than 100
  • No apnea
  • No diaphoresis
  • No anxiety
  • No respiratory distress
Does the patient pass these? If no, then place the patient back on the original settings and notify the physician that patient is not ready to be weaned. If yes, then perform weaning parameters. 
  • NIF equal to or greater than 20 cwp
  • FVC less than 10 ml/kg
  • VT of greater than 5 ml/kg (or appropriate for patient)
  • Respiratory rate less than 30
  • Minute Ventilation greater than 5 and less than 15
  • RSBI (f/vt) less than 100
If the patient fails, then place patient back on original settings. 

3.  Extubation.  If the patient passes, then you continue the SBT for 30 minutes to a couple hours. Then you redo the screen. If the patient continues to do well, you can draw and ABG and discuss with the patient's nurse and doctor to see if the patient can be extubated. 

Every ventilator extubation protocol will have its differences from this one, although they should all be with the same goal of speeding time of intubation to extubation, and the overall goal is to prevent VAP and other ventilator associated events (VAE).

Note: This post was edited on July 5, 2016, by John A. Bottrell

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