2021B05 Draw, label and describe the waveforms and pressures that are seen in each anatomical location during insertion of a pulmonary artery catheter.

 

List:

        Pressure trace

        Normal pressures

        Waveform components

        Factors increasing pressures

 

Pressure trace:

Diagram, schematic

Description automatically generated

 

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 = RAP

      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 = LAP

Wedge = balloon inflated to occlude a pulmonary artery branch

      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)

 

 

Feedback welcome at ketaminenightmares@gmail.com