Marino The ICU Book 4e, IE

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The Pulmonary Artery Catheter

capillary hydrostatic pressure is higher than the wedge pressure, a normal wedge pressure measurement will not rule out the diagnosis of hydrostatic pul- monary edema. Therefore, the use of a normal wedge pressure as a diag- nostic criterion for ARDS should be abandoned. THERMODILUTION CARDIAC OUTPUT The ability to measure cardiac output increases the monitoring capacity of the PA catheter from 2 parameters (i.e., central venous pressure and wedge pressure) to at least 10 parameters (see Tables 8.1 and 8.2), and allows a physiologic evaluation of cardiac performance and systemic oxygen transport.

Temp

Time

Thermistor Output

3

Proximal Port Injection

1

2

Injectate mixes with Blood

FIGURE 8.5 The thermodilution method of measuring cardiac output. See text for explanation.