Shock Syndromes I

Value

Equation (as applicable)

Normal Value

Pulmonary artery diastolic pressure

(PADP)

8–12 mm Hg

Mean pulmonary artery pressure (mPAP)

[PASP + (2 × PADP)]/3

12–15 mm Hg

Pulmonary capillary wedge pressure

(PCWP) or pulmonary arterial occlusion

pressure (PAOP)

5–12 mm Hg

Central venous pressure (CVP) or right

atrial pressure (RAP)

2–6 mm Hg

Pulmonary vascular resistance (PVR)c

80 × [(mPAP − PCWP)/CO]

(divide by 80 for Wood units)

20–120 dynes•s•cm-5

(< 2 Wood units)

Systemic vascular resistance (SVR)c

80 × [(MAP − CVP)/CO]

800–1200 dynes•s•cm-5

Oxygen delivery (Do2)d

10 × CO (L/min) × Cao2

520–570 mL/min/m2

Arterial oxygen content (Cao2)d

(1.34 × Hgb × Sao2) +

(0.003 × Pao2)

20 mL/dL

Venous oxygen content (Cvo2)d

(1.34 × Hgb × Svo2) +

(0.003 × Pvo2)

15 mL/dL

Resting oxygen consumption (Vo2)d

10 × CO (L/min) × (Cao2 − Cvo2)

110–160 mL/min/m2

Oxygen extraction ratio (O2ER)

Vo2/Do2 × 100

20%–30%

aMay be directly measured or calculated.

bMay be measured using several mechanisms, including thermodilution with a pulmonary artery catheter. May also be calculated using the Fick equation (see later in

the chapter).

cMay also be expressed as an indexed value calculated by dividing the value by body surface area. BSA = body surface area in square meters.

dAll are components of the Fick principle for cardiac output measurement.

BSA = body surface area; Cao2 = arterial oxygen content; CI = cardiac index; CO = cardiac output; Cvo2 = venous oxygen content; CVP = central venous pressure;

DBP = diastolic blood pressure; Do2 = oxygen delivery; Hgb = hemoglobin; HR = heart rate; MAP = mean arterial pressure; mPAP = mean pulmonary artery

pressure; O2ER = oxygen extraction ratio; PADP = pulmonary artery diastolic pressure; Pao2 = arterial partial pressure of oxygen or arterial oxygen tension;

PAOP = pulmonary arterial occlusion pressure; PASP = pulmonary arterial systolic pressure; PCWP = pulmonary capillary wedge pressure; Pvo2 = venous partial

pressure of oxygen or venous oxygen tension; PVR = pulmonary vascular resistance; RAP = right atrial pressure; Sao2 = arterial oxygen saturation; SBP = systolic

blood pressure; SV = stroke volume; Svo2 = venous oxygen saturation; Vo2 = resting oxygen consumption.

3rd ed. Module 2: Critical Care. Kansas City, MO: American College of Clinical Pharmacy, 1998:87-127.

pressure allows redistribution of cardiac output (CO) to vital organs.

Blood pressure is the product of CO and systemic vascular resistance (SVR).

CO is the product of heart rate and stroke volume (SV).

SV is determined by many factors, but predominantly preload, intrinsic contractility, and afterload.

Preload refers to ventricular end-diastolic volume and is proportionally related to SV (i.e., when

preload increases, the SV increases) by the Frank-Starling mechanism (though the magnitude of

this relationship is reduced beyond a point of ventricular increasing end-diastolic volume).

Intrinsic contractility is the ability of the myocardium to contract and may be reduced by several

factors, including myocardial ischemia, cardiomyopathy, and sepsis.

Afterload is the force the ventricle must overcome to eject its volume and is inversely related to SV

(i.e., when afterload increases, the SV decreases). Left ventricular (LV) afterload is predominantly

influenced by aortic pressure, whereas right ventricular (RV) afterload is predominantly influenced

by pulmonary artery pressure.