Marino The ICU Book 4e, IE

144 Hemodynamic Monitoring

and the popular measure of body size for hemodynamic measurements is the body surface area (BSA), which can be determined with the follow- ing simple equation (17). BSA (m 2 ) = Ht (cm) + Wt (kg) – 60/100 (8.3) Why not use body weight to adjust for body size? BSA was chosen for hemodynamic measurements because cardiac output is linked to meta- bolic rate, and the basal metabolic rate is expressed in terms of body sur- face area. The average-sized adult has a body surface area of 1.7 m 2 .

Parameter Table 8.1

Hemodynamic and Oxygen Transport Parameters

Abbreviation

Normal Range

Central Venous Pressure

CVP

0 – 5 mm Hg 6 –12 mm Hg

Pulmonary Artery Wedge Pressure

PAWP

2.4 – 4.0 L/min/m 2

Cardiac Index Stroke Index

CI SI

20 – 40 mL/m 2

25–30 Wood Units †

Systemic Vascular Resistance Index Pulmonary Vascular Resistance Index

SVRI

1– 2 Wood Units †

PVRI

520 – 570 mL/min/m 2 110 –160 mL/min/m 2

Oxygen Delivery (Index) Oxygen Uptake (Index) Oxygen Extraction Ratio

DO 2 VO 2

O 2

ER

0.2 – 0.3

† mm Hg/L/min/m 2

Cardiovascular Parameters The following parameters are used to evaluate cardiac performance and mean arterial pressure. The normal ranges for these parameters are in- cluded in Table 8.1. Parameters that are adjusted for body surface area are identified by the term index . CentralVenous Pressure When the PA catheter is properly placed, the proximal port of the catheter should be situated in the right atrium, and the pressure record- ed from this port should be the right atrial pressure (RAP). As mentioned previously, the pressure in the right atrium is the same as the pressure in the superior vena cava, and these pressures are collectively called the cen- tral venous pressure (CVP). In the absence of tricuspid valve dysfunction, the CVP should be equivalent to the right-ventricular end-diastolic pres- sure (RVEDP). CVP = RAP = RVEDP (8.4)