What is involved in a bedside Swan-Ganz (pulmonary artery catheterization) procedure, including the role of the provider, the pressures monitored by the different color wires, and the normal pressure values, in a critically ill patient?

Bedside Swan-Ganz Catheter Procedure and Hemodynamic Monitoring

Provider Role and Procedural Steps

The provider must establish central venous access using strict sterile technique, advance the flow-directed balloon-tipped catheter through the right heart chambers into the pulmonary artery, and continuously monitor pressure waveforms to confirm proper positioning while avoiding life-threatening complications such as pulmonary artery rupture. 1

Pre-Insertion Requirements

• Obtain central venous access via internal jugular, subclavian, or femoral vein using percutaneous technique with full sterile barriers including gown, gloves, mask, and large sterile drape 1, 2
• Zero the pressure transducer at the mid-thoracic line (halfway between anterior sternum and bed surface in supine position) before insertion 2, 3
• Verify equipment function including balloon integrity by inflating with 1.5 mL air before insertion 1

Insertion Technique

• Advance the catheter through a large-bore introducer sheath (typically 8-8.5 French) placed in the central vein 1, 4
• Monitor continuous pressure waveforms on the bedside monitor as the catheter advances through each cardiac chamber 1
• Inflate the balloon with 1.5 mL of air once the catheter tip reaches the right atrium (typically 15-20 cm from internal jugular insertion site) to allow flow-directed advancement 4, 5
• Advance the catheter sequentially through right atrium → right ventricle → pulmonary artery → wedge position, guided by characteristic pressure waveform changes 4, 5
• Deflate the balloon immediately once pulmonary artery position is confirmed and secure the catheter at 40-50 cm depth from internal jugular approach 6, 5

Catheter Lumens and Color Coding

While specific color coding varies by manufacturer, the standard 7.5 French Swan-Ganz catheter contains four lumens with distinct functions 4:

Distal (Yellow) Lumen

• Opens at the catheter tip in the pulmonary artery 4
• Measures pulmonary artery pressure (PAP) continuously and pulmonary capillary wedge pressure (PCWP) when balloon is inflated 1, 3
• Allows blood sampling for mixed venous oxygen saturation (SvO2) from pulmonary artery 1, 4

Proximal (Blue) Lumen

• Opens 30 cm from catheter tip in the right atrium 4
• Measures central venous pressure (CVP) or right atrial pressure (RAP) 1
• Serves as infusion port for medications and fluids 4

Balloon Inflation Port (Red)

• Connects to the balloon at the catheter tip 4
• Inflated with 1.5 mL air only to obtain wedge pressure measurements 6, 3
• Must never be inflated with liquid to prevent balloon rupture 5

Thermistor Connector (White/Orange)

• Contains temperature sensor 4 cm from catheter tip 4
• Measures cardiac output via thermodilution technique when cold saline is injected through proximal port 4, 7

Pressure Waveforms and Normal Values

Right Atrial Pressure (RAP/CVP)

• Normal range: 2-8 mmHg 1
• Waveform shows a and v waves corresponding to atrial contraction and venous filling 3
• **Low values (<2 mmHg) suggest hypovolemia**; high values (>8 mmHg) may indicate volume overload, right ventricular failure, or tricuspid regurgitation 1

Right Ventricular Pressure (RVP)

• Normal systolic: 15-30 mmHg 4
• Normal diastolic: 2-8 mmHg (should equal RAP) 4
• Waveform shows sharp systolic upstroke with diastolic pressure equal to RAP 4, 5

Pulmonary Artery Pressure (PAP)

• Normal systolic: 15-30 mmHg 4
• Normal diastolic: 8-15 mmHg 4
• Normal mean: 10-20 mmHg 3, 4
• Waveform shows dicrotic notch from pulmonic valve closure 4, 5

Pulmonary Capillary Wedge Pressure (PCWP)

• Normal range: 6-12 mmHg 3
• Values >15 mmHg indicate elevated left ventricular filling pressures suggesting left heart failure or volume overload 3
• Waveform shows characteristic a and v waves similar to left atrial tracing 3
• Must be measured at end-expiration in spontaneously breathing patients or end-inspiration in mechanically ventilated patients to minimize respiratory artifact 3

Critical Safety Measures

Preventing Pulmonary Artery Rupture

• Never inflate the balloon without first checking the pressure waveform for damping, as this indicates distal migration and balloon inflation will cause vessel rupture, which is fatal in 50% of cases 6, 8
• Reserve wedge pressure measurement as a specific diagnostic event rather than routine monitoring 6
• Withdraw the catheter into the main pulmonary artery before cardiopulmonary bypass to prevent distal migration during cardiac manipulation 6
• Limit catheter residence time to 5-7 days maximum due to increasing infection risk (2.6 per 1,000 catheter days) and vessel injury risk 2

Verification of Proper Wedge Position

• Confirm characteristic a and v waves in the wedge tracing 3
• Obtain blood gas from wedged position showing oxygen saturation equal to systemic arterial blood (>95%) 3
• Measure from multiple pulmonary segments to exclude segmental variations 3
• Ensure mean wedge pressure is lower than mean PAP by at least 2-3 mmHg 3

Clinical Interpretation

Hemodynamic Profiles

• PCWP >15 mmHg with elevated PAP indicates post-capillary pulmonary hypertension from left heart disease 3
• PCWP ≤12 mmHg with elevated PAP suggests pre-capillary pulmonary hypertension from pulmonary vascular disease 3
• Low CVP (<2 mmHg) with low PCWP (<6 mmHg) indicates hypovolemia requiring fluid resuscitation 1
• High CVP (>12 mmHg) with normal PCWP suggests isolated right ventricular failure from pulmonary hypertension or RV ischemia 1

Important Limitations

• CVP and PCWP are insensitive indicators of volume status; low values may reflect hypovolemia, but high values do not necessarily indicate volume overload 1
• PCWP may not accurately reflect left ventricular end-diastolic pressure in conditions such as mitral stenosis, elevated pulmonary vascular resistance, or reduced ventricular compliance 1
• Dynamic indicators such as stroke volume variation are more reliable than static pressures for predicting fluid responsiveness 1

Common Pitfalls to Avoid

• Never advance the catheter with the balloon deflated beyond 15 cm from the introducer, as this risks ventricular arrhythmias and myocardial perforation 5
• Never use more than 1.5 mL air for balloon inflation, as overinflation causes vessel rupture 6, 8
• Never measure pressures during active patient movement, coughing, or Valsalva maneuvers, as these create artifactual pressure swings 3
• Never rely on PCWP alone in atrial fibrillation, as irregular rhythm invalidates pressure measurements 3
• Always withdraw the catheter if the waveform shows spontaneous wedging (loss of pulsatility), indicating dangerous distal migration 6