L.13 Intra cardiac pressures and measurement

Question 1

What are the 3 atrial pressure waves (increase in atrial pressure) observed in the jugular veins

Answer 1

A wave: retrograde pressure pulse when atria contract as no valves between.
C wave: during early ventricular systole
V wave: gradual pressure increase during reduced ejection and isovolumic phase

Question 2

How is a pulmonary artery wedge pressure taken

Answer 2

Advance a swan-Ganz (fluid filled catheter with pressure transducer at the tip) into the chambers of the heart through a vein/ artery until it gets to the pulmonary artery.
It has an inflatable balloon on the end so inflated it detects left atrial pressure, uninflated it does pulmonary artery pressure.

Question 3

What is ficks principle used to calculate

Answer 3

Catheters are inserted into the vein (pulmonary vein) and an artery (pulmonary artery) to get a sample of mixed venous blood and a sample of arterial blood.
The O2 concentration in the samples is found, and the O2 consumption is found on a respirator

CO= oxygen consumption / (arterial O2 – mixed venous O2)

Question 4

What does thermodilution using a triple lumen catheter-
(One tip for temperature sensor, one tip for saline injection, on tip for pressure transducer)-
help find

Answer 4

Known volume of cold saline is injected into the right atrium and the change in temperature of the mixed blood at the pulmonary artery is measured by a temperature sensor.
The integration of the curve helps to work out the CO