CVP

Question 1

Determinants of CVP

Answer 1

Determinants of CVP
* Intravascular fluid status
* Mean Systemic Filling Pressure
( venousTone)
* T V integrity
* RV Compliance
* RV Contractility
* Pulmonary vascular resistance
* Cardiac rhythm
* Transducer level

Question 2

CVP Physiological basis

Answer 2

Physiological basis:
* CVP is an approximation of RAP → a major determinant of RV filling.
* Assumption → CVP is a good indicator of preload.
* LV stroke volume is determined by RV stroke volume.
* CVP is considered / assumed to be an indirect measure of LV preload.
* ΔCVP within fluid challenge is thought to be useful in determining fluid responsiveness.

Question 3

CVP waveform

Answer 3

Question 4

Waveform Components

Answer 4

=>a wave — Atrial systole (End-diastole)
->↑ in Tricuspid stenosis / Pulmonary stenosis
->↑in RV failure (↑resistance to forward flow)

->Absent in:
* Atrial fibrillation

->Cannon a waves in:
* Junctional rhythm
* AV dissociation (e.g. complete heart block, Ventricular Tachycardia) due to RA contraction against closed TV

Question 5

x-descent

Answer 5

x-descent — Mid-systole
->Due to RA relaxation
* ↑(steep descent) in Constrictive pericarditis
* ↓ or absent in: TR

Question 6

c wave — Early systole

Answer 6

->Bulging of tricuspid valve cusps into RA
->Prominent in:
* Tricuspid regurgitation—»
- Fusion of c + v waves
- Blunting of x-descent

Question 7

v wave — Late systole

Answer 7

v wave — Late systole
* Rapid filling of RA
* ↑ in:
* Tricuspid regurgitation (filling from 2 sites: TV + venous return)

Question 8

y-descent — Early diastole

Answer 8

=>y-descent — Early diastole
* Early ventricular filling
->↑ in:
Constrictive pericarditis (LV filling impaired)
-> ↓ in:
* Tamponade (pericardial fluid pressure)

Question 9

Limitations of CVP

Answer 9

CVP determined by factors other than intravascular volume, e.g.
* Venous tone → mean systemic filling pressure
* RA & RV compliance
* LV compliance
* Valvular integrity
* Intrathoracic & pleural pressure
* Intra-abdominal pressure
(from LITFL)
* In critically ill, there is a poor correlation between CVP & RVEDV.