I did a podcast with Chip Lange from TOTAL EM on post intubation acronym's for trouble shooting uncomfortable and restless intubated patients. I got some emails asking about the "M" “Make it easier to trigger a breath."
I'm not completely sold on this acronym for multiple reasons, but I do think it provides a quick reference to checklist your way down. I also have changed the wording to "Think about paralytics" rather than "Turn to paralytics". For all intents and purposes the ideas still remain the same.
Before we begin...
Imagine a syringe when we talk about this. There are two ways to make the plunger depress. You can either pull on the plunger or force air into the tip. We obviously know with ventilator driven breaths the volume is being delivered through the tip. When we talk about patient triggered breaths, the patient is initiating the breath by pulling on the plunger or withdrawing a flow or certain degree of negative pressure from the circuit to trigger a breath.
Pressure & Flow
Flow Trigger uses a feedback device (flow sensor) that is usually placed at the Y site of the circuit. It will detect interruption in the bias flow. WTH is bias flow? This is a constant flow that circulates the ventilator circuit during exhalation. I did a podcast covering this in detail here.
The bias flow is usually somewhere in the 3-5 liter per minute range. The ventilator will ask you to select a flow trigger value in liter per minute, but it helps to think about this in ML’s per second.
If a flow trigger is set to 3 lpm the patient would trigger a breath as soon as they inhale at a speed of 50ml’s/ sec. This wouldn’t mean the patient has to actually breathe in 50ml’s in one second. Its the speed at which the patient pulls flow from the bias flow.
Pressure Trigger requires the patient to withdraw a certain amount of negative pressure below PEEP or baseline. This can require a bit more work than a flow trigger. Consider additional appliances that may make it more difficult to trigger a breath.
How do we know it's time to decrease the trigger threshold?
1.Look at the patient
3. P0.1 parameter
All of this & more in this weeks podcast!