Hemodynamic Measurements |
|
| Parameter | Normal Value |
| Cl = CO / BSA | 2.5-4.2 L/min/m2 |
| SVl = Cl / HR x 1000 | 36-48 ml/beat/m2 |
| LVSWl = (MAP - PCWP) x SVl (x 0.0136) | 44-56 gm m/m2 |
| RVSWl = (MPAP - CVP) x SVl (x 0.0136) | 7-10 gm m/m2 |
| MAP = {SAP + (DAP x 2)}/3 | 80-100 mm Hg |
| SVR = (MAP - CVP) / CO x 80 | 1200-1500 dynes sec/cm5 |
| PVR = (MPAP - PCWP) / CO x 80 | 80-240 dynes sec/cm5 |
| 02 Delivery (DO2) = CO x Ca02 | 500-600 ml/min |
| 02 Uptake (VO2) = C0 x (Ca02 - Cv02) | 110-160 ml/min |
| 02 Extraction Ration = V02/D02 | 22-32 |
| Arterial 02 Content Difference (Ca02 - Cv02) | 3-5 vol % |
Arterial Pressure
Waveform
Wave Reflections
- Incidence Wave
- Function of LV stroke volume & compliance
- Reflected Wave
- Originates at bifurcation points
- Function of peripheral vasculature resistance
Components of a Pressure Recording System
Intravascular Catheter
Connecting Tubing
Transducer
Continuos Flush Device
Amplifier
Data Display Device
Arterial Pressure
Recording Artifacts
Resonant Systems
- Resonant Frequency
- Damping Factor
Waveform Distortion
- Flush Test
- To determine whether recording system is distorting the pressure waveform
- f = paper speed / distance between oscillation
Technique
Allen's Test
- Normal: 7 s
- Inadequate collateral flow > 14 s
Complications
- Radial artery thrombosis > 40% in vessels cannulated > 40 h (3% permanent); septicemia 1-2%
- Femoral artery complication rate 7-10%; infection rate 1-3%
Pressure Monitoring
MAP = |
SAP + (DAP x 2) |
| 3 |
Pulmonary Artery Pressure
Advancing the Catheter
50-55 cm from right subclavian site to wedge position
Waveforms
Transducers
Wedge Pressure
PC = PCWP = PLA = LVEDP
PC - PLA = Q x Rpulm veins
If Q = 0, then: PC = PLA (PCWP)
PCWP is equal to capillary hydrostatic pressure (PC) only when the resistance in the pulmonary veins is negligible
PC - PCWP = Q x Rpulm vein
If Rpulm vein = 0, then PC = PCWP
Pulmonary Artery Catheter
Waveform Artifacts
Respiratory Variation
PEEP
Verifying Zone III Placement
Wedged Sa02
Minimal Respiratory variation
Less than 50% increase in PCWP when PEEP is increased
Complications
Arrhythmias
- 13% incidence, Swan et al
Conduction Defects
- RBBB 3-6%
Pulmonary Infarction
Pulmonary Artery Rupture
- 0.06-0.2% incidence; 45-65% mortality
Catheter Entrapment
Balloon Rupture
Infection (Colonization 9-46%)
Thermodilution Cardiac Output
Technique
Use room temperature injectate (0.09% NaCl or 5% Dextrose in water)
Inject 10 ml within 4 s
Repeat until within 10% error
Calculation
Q = |
V x (T body - T injectate) x K1 x K2 |
| Change in blood temperature over time |
Potential Sources of Error
Tricuspid Insufficiency
R to L Shunt
L to R Shunt
Low Cardiac Output
Catheter Thrombus