Any video made by Patrick is wonderful, he’s a very respected RT up here, and I am privileged to have attended a lot of these lectures in person. He made me think a lot about ventilation and changed how I think about time constants and asynchrony. Brilliant man! Happy to have worked with him.
28:00 Question about this segment. Since static compliance is taken during a breath hold, what does he mean that we can take the exhaled Vt and divide it by the Static Compliance and the he says it's dynamic? I got lost. On the PB 980, when we measure the plateau pressure, it does a hold and also calculates the SC. So, it has already taken the Vt into account. I am assuming there's something different with other ventilators. The talking about spontaneously breathing pts. Again, thus may be a vent brand issue. Is he using a previous CS when it was a machine breath, and using it later with the pts spontaneous volume?
Definition. Driving pressure is [Pplat - PEEP] and is the pressure required for the alveolar opening . Static lung compliance (Cstat) is expressed as [VT / (Pplat - PEEP)]. Thus, driving pressure is also expressed as [VT / Cstat].
I think I get that, but how do you get a static compliance on a spontaneously breathing patient? On the PB 980 or 840, I can't get a breath hold on PSV. Does the Hamilton let you? Or is he using a previously measured Static Compliance?
Reply from Patrick: If the patient is spontaneously breathing it’s harder to get a real plat with an inspiratory hold. Using the formula allows you to at least estimate the plat if you add the peep or total peep if you can get it to the answer from vte/cstat. But either way, as long as the patient isn’t asynchronous, using the vte/cstat is adequate to get a driving pressure. You just have to remember it’s a dynamic measurement and can slightly change with each breath due to the pendeluft effect.
Any video made by Patrick is wonderful, he’s a very respected RT up here, and I am privileged to have attended a lot of these lectures in person. He made me think a lot about ventilation and changed how I think about time constants and asynchrony. Brilliant man! Happy to have worked with him.
This is gold standard Intel. Thank you!
Thanks for putting this up
28:00
Question about this segment.
Since static compliance is taken during a breath hold, what does he mean that we can take the exhaled Vt and divide it by the Static Compliance and the he says it's dynamic?
I got lost.
On the PB 980, when we measure the plateau pressure, it does a hold and also calculates the SC.
So, it has already taken the Vt into account.
I am assuming there's something different with other ventilators.
The talking about spontaneously breathing pts. Again, thus may be a vent brand issue. Is he using a previous CS when it was a machine breath, and using it later with the pts spontaneous volume?
Definition. Driving pressure is [Pplat - PEEP] and is the pressure required for the alveolar opening . Static lung compliance (Cstat) is expressed as [VT / (Pplat - PEEP)]. Thus, driving pressure is also expressed as [VT / Cstat].
I think I get that, but how do you get a static compliance on a spontaneously breathing patient? On the PB 980 or 840, I can't get a breath hold on PSV. Does the Hamilton let you? Or is he using a previously measured Static Compliance?
Reply from Patrick: If the patient is spontaneously breathing it’s harder to get a real plat with an inspiratory hold. Using the formula allows you to at least estimate the plat if you add the peep or total peep if you can get it to the answer from vte/cstat. But either way, as long as the patient isn’t asynchronous, using the vte/cstat is adequate to get a driving pressure. You just have to remember it’s a dynamic measurement and can slightly change with each breath due to the pendeluft effect.
@respiratoryCEU
Thanks for clarifying that.