A. Description
- PA catheter is a flow directed, balloon tipped devise inserted through a large vein
- Feed through right atrium (RA) into ventrical (RV) then into pulmonary artery (PA)
- Catheter is inserted into RA, balloon inflated, and then "wedged" into PA
- Pressures are recorded with balloon inflated while catheter is inserted forward
- "Wedge" pressure is pressure distal to balloon, or pressure in pulmonary capillaries
- This is called pulmonary capillary wedge pressure (PCWP)
- Can measure R sided pressures, PA pressures, and PCWP
- Generally, PCWP = LAEDP (left atrial end diastolic pressure)
- LV filling pressure = LV end diastolic pressure (LVEDP, see below)
- Other Uses of PA Catheter
- Permits determination of oxygen consumption and cardiac output
- Pacing from atrial and ventricular sites
- Measurement of core body temperature
- Measurement of intracavitary potentials
- Infusion of medications and fluids
- Use of PA catheter does not affect clinical outcomes [2,3,4,5,6,7]
- PA catheters should be considered experimental and optional at this time [5,6,7]
- Use of PA catheters has declined substantially as overall benefits outweighed by risks [8]
B. Theoretical Pressure Tracing
- Catheter is fed through a dilator-sheath device ("cordice")
- This devise is usually inserted into the R-Internal Jugular, L-Subclavian, or femoral veins
- Balloon is inflated when RA is reached
- Central venous pressure can be determined
- Catheter is further inserted with balloon up into the RV
- Arrhythmias are often seen (usually briefly) as tricuspid valve is passed
- Once in the RV (note pressure tracing change), further advance into the pulmonary artery
- In the wedged, balloon-up position in PA, PCWP is determined
- The PCWP is used to estimate LV filling (see above)
- Order of pressures is IVC/SVC (0-6cm) leads RA (0-8cm) leads to RV (20-25/6-12cm) leads to PA (20-25/10cm) leads to Wedge (6-12 cm)
[
Figure] "Pulmonary Artery Catheter Tracing"
C. Indications
- Use of PAC in variety of settings does not improve clinical outcomes [3,4,7]
- Therefore, indications are being questioned; general use should probably be discouraged
- The PAC is used to determine whether problem is with volume or heart pump function
- Thus, volume status and pump function are determined from catheter data
- Mainly in patients with hypotension and low urine output
- Potentially useful in patients with at least two major contributors to hypotension
- Other invasive monitoring (CVP, arterial pressure) are likely sufficient for shock management
- Suggested Utility (questionable [3,7])
- Complicated MI
- Congestive Heart Failure (CHF), particularly with lung disease (such as COPD)
- Multiorgan system failure (Severe Sepsis Syndrome)
- High risk obstetrics
- Shock
- Other acute renal failure (ARF)
- Complicated MI
- Cardiogenic Shock
- Severe Left Ventricular Failure
- Right Ventricular (RV) Failure
- Acute Mitral Regurgitation
- Ventricular Septal Rupture
- Cardiac Tamponade
- Recurrent severe post-infarction ischemia
- Respiratory Distress
- No improvement in clinical outcomes, but increased complications, in acute lung injury [7]
- Adult Respiratory Distress Syndrome (ARDS)
- Cardiogenic or non-cardiogenic pulmonary edema
- Massive pulmonary embolism (PE)
- Toxic inhalations
- Mechanically ventilated patients, especially with high PEEP
- Evaluation of specific causes of CHF
- Dilative Cardiomyopathy
- Constrictive versus Restrictive Disease
- Pre-capillary pulmonary hypertension
- Shock
- Septic Shock
- Hypovolemic Shock
- Cardiogenic Shock
- RV Failure due to Pulmonary Embolism
- Cardiac Tamponade
- Multiorgan-System Failure Syndromes (MODS)
- Severe Sepsis
- Extensive Burns
- Pancreatitis
- Extensive Trauma
- Persistant low output syndrome
- High Risk Obstetric Patients
- Pre-existing Cardiac Disease
- Pre-eclampsia and Eclampsia
- Abruptio placentae
- Other Indications
- Acute Renal Failure for volume management
- Cirrhosis with ascites - volume management
- Post- and intra-operative open heart and other surgeries
D. Limitations of PCWP and LVEDP Equivalency
- PA inflated balloon pressure increase PCWP
- Increased pulmonary vascular resistance (PVR)
- Heart Rate > ~120 beats per minute
- Veno-occlusive disease (VOD)
- PCWP increase Pulmonary Venous Pressure
- Catheter tip location
- Severe hypovolemia
- PEEP
- Pulmonary Venous Pressure increase LA Pressure
- Veno-occlusive disease
- Tumor venous occlusion
- LA Pressure increase LVEDP
- Mitral Valve disease
- Increased intrapleural pressure
- Aortic Valve disease
- Decreased LV compliance (with increased atrial systole)
E. Complications of Pulmonary Catheter Placement
- Arrhythmia
- Complete heart block or R bundle branch block
- Thrombosis
- Infection
- Pulmonary Infarction
- Balloon rupture
- Pulmonary artery rupture / hemorrhage
- Cardiac Tissue injury
- Catheter knotting
- Overall mortality and PA Catheter
- Randomized study in high risk surgery patients >60 years of age showed no mortality benefit or reduction in hospital stay with use of these catheters [2]
- Matched pair, retrospective study again showed increased risk of death with catheter
- The latter study controlled for severity of disease between control and subject
- Major concern over increase in deaths associated with pulmonary catheters
F. Normal Values and Calculations
- Cardiac Output (CO)
- Various methods for calculation
- Fick Method uses assumed oxygen consumption and is good for cardiac disease
- Thermodilution measures flow and is good in septic patients
- Normal value 3.0-7.0L/min, cardiac index (CI) 2.5-4.5 L/min/m2 (CI=CO/BSA)
- Systemic Vascular Resistance (SVR) = (Mean SBP-CVP) ÷ CO (nl 1000-1500 dyne/sec/cm2)
- Pulmonary Vascular Resistance (PVR) = (Mean PAP-PCWP) ÷ CO (nl 120-250 dyne/sec/cm2)
- Mixed venous saturation can be obtained from blood sample during insertion / proximal port
- Normal MVO2 ~ 75%
- MVO2 is decreased in cardiogenic shock
- MVO2 is increased in septic shock (due to AV shunting and poor perfusion)
- Stroke index = cardiac index/heart rate (normal 50-75mL/contraction)
G. Examples
Problem | BP | Pulse Pressure | HR | PCWP | CO | SVR | PVR | CVP |
---|
1. Normal | nl | 40-50 | 80 | 8-12 | 4-6 | 1500 | 150 | normal |
2. Septic Shock | low | wide | up | 4-8 | up | down | down | low |
3. Cardiogenic Shock | low | narrow | up | 20 | low | high | ± | high |
4. RV Failure | low | narrow | up / down | low | ± | high | low | very high |
5. ARDS | +/- | narrow | mostly up | low | ± | nl | up | up |
6. Hypovolemia | low | narrow | up | low | down | high | low | low |
7. Acute Mitral Regur | low | narrow | up | high | low | (prominant "V" waves) | | |
8. Acute Tamponade | low | narrow | up | high | down | high | ± | very high |
H. Additional Notes and Waveforms- Acute Tricuspid Regurgitation
- Increased CVP, right atrial, and RV end diastolic pressures
- Blunted "X" descent, steep "Y" descent
- RA and RV pressures equalized
- Constrictive Pericarditis
- Increased RA and PCW pressures
- Dip and plateau in RV pressure
- "M" or "W" shaped jugular venous pressures
- Preserved "X" and steep "Y" descents
- Restrictive Cardiomyopathy
- PCWP may be higher than RA pressure
- Similar findings to constrictive pericarditis
- Acute Ventricular Septal Rupture
- Reduced CO, increased SVR, tachycardia, hypotension
- Oxygen step-up from RA to RV and PA (due to Left to Right shunt)
References
- Swan HJC, Ganz W, Forrester J, et al. 1970. NEJM. 283:447

- Sandham JD, Hull RD, Brant RF, et al. 2003. NEJM. 348(1):5

- Richard C, Warszawski J, Anguel N, et al. 2003. JAMA. 290(20):2713

- Harvey S, Harrison DA, Singer M, et al. 2005. Lancet. 366(9484):472

- ESCAPE Investigators. 2005. JAMA. 294(13):1625

- Shah MR, Hasselblad V, Stevenson LW, et al. 2005. JAMA. 294(13):1664

- NHLBI ARDS Clinical Trials Network. 2006. NEJM. 354(21):2213

- Wiener BS and Welch HG. 2007. JAMA. 298(4):423
