A. Description

1. PA catheter is a flow directed, balloon tipped devise inserted through a large vein
   1. Feed through right atrium (RA) into ventrical (RV) then into pulmonary artery (PA)
   2. Catheter is inserted into RA, balloon inflated, and then "wedged" into PA
   3. Pressures are recorded with balloon inflated while catheter is inserted forward
2. "Wedge" pressure is pressure distal to balloon, or pressure in pulmonary capillaries
3. This is called pulmonary capillary wedge pressure (PCWP)
4. Can measure R sided pressures, PA pressures, and PCWP
   1. Generally, PCWP = LAEDP (left atrial end diastolic pressure)
   2. LV filling pressure = LV end diastolic pressure (LVEDP, see below)
5. Other Uses of PA Catheter
   1. Permits determination of oxygen consumption and cardiac output
   2. Pacing from atrial and ventricular sites
   3. Measurement of core body temperature
   4. Measurement of intracavitary potentials
   5. Infusion of medications and fluids
6. Use of PA catheter does not affect clinical outcomes [2,3,4,5,6,7]
7. PA catheters should be considered experimental and optional at this time [5,6,7]
8. Use of PA catheters has declined substantially as overall benefits outweighed by risks [8]

B. Theoretical Pressure Tracing

1. Catheter is fed through a dilator-sheath device ("cordice")
2. This devise is usually inserted into the R-Internal Jugular, L-Subclavian, or femoral veins
3. Balloon is inflated when RA is reached
   1. Central venous pressure can be determined
   2. Catheter is further inserted with balloon up into the RV
   3. Arrhythmias are often seen (usually briefly) as tricuspid valve is passed
4. Once in the RV (note pressure tracing change), further advance into the pulmonary artery
   1. In the wedged, balloon-up position in PA, PCWP is determined
   2. The PCWP is used to estimate LV filling (see above)
5. 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

1. Use of PAC in variety of settings does not improve clinical outcomes [3,4,7]
2. Therefore, indications are being questioned; general use should probably be discouraged
3. The PAC is used to determine whether problem is with volume or heart pump function
   1. Thus, volume status and pump function are determined from catheter data
   2. Mainly in patients with hypotension and low urine output
   3. Potentially useful in patients with at least two major contributors to hypotension
4. Other invasive monitoring (CVP, arterial pressure) are likely sufficient for shock management
5. Suggested Utility (questionable [3,7])
   1. Complicated MI
   2. Congestive Heart Failure (CHF), particularly with lung disease (such as COPD)
   3. Multiorgan system failure (Severe Sepsis Syndrome)
   4. High risk obstetrics
   5. Shock
   6. Other acute renal failure (ARF)
6. Complicated MI
   1. Cardiogenic Shock
   2. Severe Left Ventricular Failure
   3. Right Ventricular (RV) Failure
   4. Acute Mitral Regurgitation
   5. Ventricular Septal Rupture
   6. Cardiac Tamponade
   7. Recurrent severe post-infarction ischemia
7. Respiratory Distress
   1. No improvement in clinical outcomes, but increased complications, in acute lung injury [7]
   2. Adult Respiratory Distress Syndrome (ARDS)
   3. Cardiogenic or non-cardiogenic pulmonary edema
   4. Massive pulmonary embolism (PE)
   5. Toxic inhalations
   6. Mechanically ventilated patients, especially with high PEEP
8. Evaluation of specific causes of CHF
   1. Dilative Cardiomyopathy
   2. Constrictive versus Restrictive Disease
   3. Pre-capillary pulmonary hypertension
9. Shock
   1. Septic Shock
   2. Hypovolemic Shock
   3. Cardiogenic Shock
   4. RV Failure due to Pulmonary Embolism
   5. Cardiac Tamponade
10. Multiorgan-System Failure Syndromes (MODS)
    1. Severe Sepsis
    2. Extensive Burns
    3. Pancreatitis
    4. Extensive Trauma
    5. Persistant low output syndrome
11. High Risk Obstetric Patients
    1. Pre-existing Cardiac Disease
    2. Pre-eclampsia and Eclampsia
    3. Abruptio placentae
12. Other Indications
    1. Acute Renal Failure for volume management
    2. Cirrhosis with ascites - volume management
    3. Post- and intra-operative open heart and other surgeries

D. Limitations of PCWP and LVEDP Equivalency

1. PA inflated balloon pressure increase PCWP
   1. Increased pulmonary vascular resistance (PVR)
   2. Heart Rate > ~120 beats per minute
   3. Veno-occlusive disease (VOD)
2. PCWP increase Pulmonary Venous Pressure
   1. Catheter tip location
   2. Severe hypovolemia
   3. PEEP
3. Pulmonary Venous Pressure increase LA Pressure
   1. Veno-occlusive disease
   2. Tumor venous occlusion
4. LA Pressure increase LVEDP
   1. Mitral Valve disease
   2. Increased intrapleural pressure
   3. Aortic Valve disease
   4. Decreased LV compliance (with increased atrial systole)

E. Complications of Pulmonary Catheter Placement

1. Arrhythmia
2. Complete heart block or R bundle branch block
3. Thrombosis
4. Infection
5. Pulmonary Infarction
6. Balloon rupture
7. Pulmonary artery rupture / hemorrhage
8. Cardiac Tissue injury
9. Catheter knotting
10. Overall mortality and PA Catheter
    1. 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]
    2. Matched pair, retrospective study again showed increased risk of death with catheter
    3. The latter study controlled for severity of disease between control and subject
    4. Major concern over increase in deaths associated with pulmonary catheters

F. Normal Values and Calculations

1. Cardiac Output (CO)
   1. Various methods for calculation
   2. Fick Method uses assumed oxygen consumption and is good for cardiac disease
   3. Thermodilution measures flow and is good in septic patients
   4. Normal value 3.0-7.0L/min, cardiac index (CI) 2.5-4.5 L/min/m2 (CI=CO/BSA)
2. Systemic Vascular Resistance (SVR) = (Mean SBP-CVP) ÷ CO (nl 1000-1500 dyne/sec/cm2)
3. Pulmonary Vascular Resistance (PVR) = (Mean PAP-PCWP) ÷ CO (nl 120-250 dyne/sec/cm2)
4. Mixed venous saturation can be obtained from blood sample during insertion / proximal port
   1. Normal MVO2 ~ 75%
   2. MVO2 is decreased in cardiogenic shock
   3. MVO2 is increased in septic shock (due to AV shunting and poor perfusion)
5. Stroke index = cardiac index/heart rate (normal 50-75mL/contraction)

G. Examples

H. Additional Notes and Waveforms

1. Acute Tricuspid Regurgitation
   1. Increased CVP, right atrial, and RV end diastolic pressures
   2. Blunted "X" descent, steep "Y" descent
   3. RA and RV pressures equalized
2. Constrictive Pericarditis
   1. Increased RA and PCW pressures
   2. Dip and plateau in RV pressure
   3. "M" or "W" shaped jugular venous pressures
   4. Preserved "X" and steep "Y" descents
3. Restrictive Cardiomyopathy
   1. PCWP may be higher than RA pressure
   2. Similar findings to constrictive pericarditis
4. Acute Ventricular Septal Rupture
   1. Reduced CO, increased SVR, tachycardia, hypotension
   2. Oxygen step-up from RA to RV and PA (due to Left to Right shunt)

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References

1. Swan HJC, Ganz W, Forrester J, et al. 1970. NEJM. 283:447
2. Sandham JD, Hull RD, Brant RF, et al. 2003. NEJM. 348(1):5
3. Richard C, Warszawski J, Anguel N, et al. 2003. JAMA. 290(20):2713
4. Harvey S, Harrison DA, Singer M, et al. 2005. Lancet. 366(9484):472
5. ESCAPE Investigators. 2005. JAMA. 294(13):1625
6. Shah MR, Hasselblad V, Stevenson LW, et al. 2005. JAMA. 294(13):1664
7. NHLBI ARDS Clinical Trials Network. 2006. NEJM. 354(21):2213
8. Wiener BS and Welch HG. 2007. JAMA. 298(4):423