Venous Pressure Monitoring

swan-ganz (PA) catheter

flexible, radio-opaque 7 Fr, 110 cm PVC catheter marked in 10 cm increments from distal tip. PVC remains pliable at room temp and softens at body temp

swan-ganz (PA) catheter use

Obtains direct invasive hemodyamics - CVP, PAP, PCWP, SvO2, CO in high-risk cardiac surgical cases, cardiogenic shock, and mechanical circulatory support evaluation

PAC distal lumen (yellow)

measures pulmonary artery pressure (PAP) continuously and pulmonary capillary wedge pressure (PCWP) when wedged. Used to draw true mixed venous blood samples (SvO2). Terminates at catheter tip

PAC proximal lumen (blue)

measures central venous pressure (CVP), carries cold injectate for thermodilution CO, infusion site for vasoactive drugs. Terminates 30 cm above distal tip, positioning the opening in the RA when distal tip is in PA

PAC balloon port

Port closed with a stopcock and inflated with air during insertion to cushion tip and allow blood to “float” the catheter into the PA. Wedged to occlude antegrade flow and measure PCWP

PAC thermistor

Temperature-sensing electrical leads terminating 4 cm behind catheter tip in PA. Measures core blood temp in PA and detects change over time following cold injectate push to calculate CO via thermodilution

Multi-lumen access catheter (MAC/Cordis)

Large bore central venous access sheath (approx 9 Fr) with a hemostatic valve. High volume fluid resuscitation capability and houses the portal for PAC insertion

CVP/PAC insertion sites

Right internal jugular vein is preferred - short, direct shot into RA and lowest risk for pneumothorax and displacement. Subclavian vein carries higher risk of pneumothorax, femoral vein carries higher risk of infection and thrombosis.

seldinger technique

standard medical procedure for percutaneous access to blood vessels

seldinger steps

vessel cannulation with syringe needle. advance guidewire through needle. remove needle while maintaining wire position. dilate tissue tract over wire. advance catheter over guidewire. remove guidewire and secure line.

normal RAP

2-8 mmHg, low-pressure rolling hills waveform

normal RVP

15-25 / 3-8 mmHg, tall steep systolic towers with very low DBP and NO dicrotic notch

normal PAP

15-25 / 8-15 mmHg, Mean: 10-20 mmHg. Diastolic pressure step-up, dicrotic notch = pulmonic valve closure

normal PCWP/PAWP/LAP

Mean 8-15 mmHg; higher rolling hills waveform

pulmonary capillary wedge pressure (PCWP/PAWP)

Pressure measured when inflated balloon occludes antegrade flow in a small PA branch. Creates static fluid column through pulmonary capillaries to LA (Pascal’s Principle). Reflects LAP and LVEDP/LV preload.

a wave - CVP waveform

Atrial contraction (follows EKG P-wave)

c wave - CVP waveform

Tricuspid valve bulging during early systole.

x descent - CVP waveform

Atrial relaxation and downward pull of tricuspid valve during ventricular ejection

v wave - CVP waveform

Passive atrial filling against closed tricuspid valve

y descent - CVP waveform

Atrial emptying into ventricles after tricuspid valve opens

absent a wave - CVP waveform

Loss of effective atrial contraction or atrial kick, usually caused by A-fib or junctional rhythms

elevated v wave - CVP waveform

Hallmark of tricuspid regurgitation. Pressure from RV systole reads in the RA

mixed venous oxygen saturation (SvO2)

Blood drawn from PAC distal lumen provides a true mixed venous saturation because coronary artery drainage from the coronary sinus has thoroughly mixed in the right heart with systemic venous drainage. Reflects global balance between DO2 and VO2. Some PACs have fiber-optics to measure, most require sampling.

thermodilution CO

A known volume of cold saline is rapidly injected into proximal RA port. Distal thermistor records the resulting temperature drop curve in the PA, area underneath is inversely proportional to CO.

pacing catheters

specialized central venous or PACs with electrical pacing wires that contact RV endocardium to induce depolarization in bradycardia or heart block

PAC complications

Insertion: Ventricular arrhythmias (PVCs, Vtach), pneumothorax, bleeding/hematoma, arterial puncture. Indwelling: PA rupture or infarction, knotting, infection, endocardial or valve trauma

PAP monitoring system

PAC catheter, introducer sheath (cordis), non-compliant pressure tubing, 3 way stopcocks, pressure transducers, continuous flush system with heparinized saline and pressure bag (300 mmHg), transducer cable, pressure monitor, continuous EKG leads

elevated a wave - CVP waveform

Caused by increased resistance to RA emptying, requiring greater pressure and force to push into RV. Sign of reduced tricuspid stenosis, reduced RV compliance, pulmonary HTN and increased RV afterload.

cannon a wave - CVP waveform

Massive atrial pressure spike when RA contracts against a closed tricuspid valve. Caused by AV dissociation, AV block, junctional rhythms where atria and ventricles contract simultaneously.