Where to read wedge in CPAP, PS, and PC ventilation?

[HillaryC, RN, CRNA]

Yesterday at work, two of the attendings were trying to figure out/remember where you read a wedge when the patient is on PC ventilation. They even asked our head nurse's opinion, but she wasn't sure either. I recently had the same confusion about patients on CPAP and PS ventilation, but they all said that you read the wedge at the "peak" of the waveform. I understand the thinking with CMV/AC ventilation versus spontaneous breathing off the vent, but I'm still a little confused about the rationale with CPAP, PS, and PC ventilation. I was also wondering about APRV. Does anyone here know the answer? Thanks!

Hillary

[versatile_kat]

Yesterday at work, two of the attendings were trying to figure out/remember where you read a wedge when the patient is on PC ventilation. They even asked our head nurse's opinion, but she wasn't sure either. I recently had the same confusion about patients on CPAP and PS ventilation, but they all said that you read the wedge at the "peak" of the waveform. I understand the thinking with CMV/AC ventilation versus spontaneous breathing off the vent, but I'm still a little confused about the rationale with CPAP, PS, and PC ventilation. I was also wondering about APRV. Does anyone here know the answer? Thanks!

Hillary

From what I remember taking care of ventilated patients, as long as they have some type of PEEP onboard, you read the wedge at the bottom (includes all ventilator settings). I always remembered it as "vent = valley, person = peak". The added PEEP gave an increased intrathoracic pressure that changed the level of the PAOP waveform. Once they are extubated, the PAOP should read the same number, except at the top of the waveform. Unless the patient has some tyoe of severe mitral valve disorder, then the numbers should be pretty close.

Hope this helps ... and please correct me if I'm wrong!