2012B09 Describe the waveforms and pressures that are seen in each anatomical location during
insertion of a pulmonary artery catheter. What factors may increase these pressures?

 

List:

·         Pressure trace

·         Normal pressures

·         Waveform components

·         Factors increasing pressures

 

Pressure trace:

 

Normal pressures:

CVP

0-5cmH2O

RVP

25/0 mmHg (pressure can be subatmospheric during filling)

PAP

25/8 mmHg

PCWP

6-12 mmHg

 

Waveform components:

CVP

(IJV, SVC, RA)

·   a wave: atrial contraction

·   c wave: closure of TV

·   x descent: TV pulled downward, atrium relaxes and elongates

·   v wave: atrial filling during ventricular systole

·   y descent: open of TV, diastolic filling

RVP

·   Atrial systole: small upstroke beforehand

·   Systolic upstroke: isovolumic contraction, rapid ejection, reduced ejection, protodiastole

·   Diastole: isovolumic relaxation, rapid filling, diastasis, atrial systole, protosystole

PAP

·   Systole (as above)

·   Diastole (above)

·   Dicrotic notch: due to reflection and resonance

PCWP

·   a-c wave: atrial systole and closure of MV

·   x descent: MV pulled down, atrium relaxes and elongates

·   v wave: atrial filling during ventricular systole

·   y descent: opening of MV, rapid ventricular filling

 

Factors increasing pressures:

CVP

·   ↑Central venous blood volume

o ↑Venous tone

o Skeletal muscle pump

o Diaphragm pump

o Right ventricular failure

o TR, TS

·   ↓Central venous compliance

o Positive pressure ventilation

o Straining

RVSP

·   Pulmonary hypertension

·   Pulmonary stenosis

mPAP

·   Secondary to LV failure

·   Secondary to thromboembolic disease

·   Secondary to chronic hypoxia

o V/Q mismatch: e.g. severe COPD / emphysema

o Low VA: e.g OSA, OHS

o Low PiO2: high altitude

·   Inflammatory or connective tissue disease

·   Idiopathic

PCWP

·   ↑Venous return

·   ↓LV compliance

·   ↓LV emptying (↓LV contractility, ↑LV afterload)

 

 

 

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