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Chapter 27: Cardiovascular Formulas and Parameters

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INTRODUCTION

Arterial oxygen content of the blood:

CaO2(mL O2​/dL)=(SaO2× Hemoglobin × 1.36) + 0.003*(PaO2)

  • 0.003*PaO2 represents the fraction of dissolved oxygen in the blood

Venous oxygen content of the blood:

CvO2(mL O2​/dL)=(SvO2× Hemoglobin × 1.36) + 0.003*(PvO2)

Arterial-mixed venous oxygen content difference:

avDO2=CaO2−CvO2

  • CaO2 ∼20 mL/dL

  • CvO2 ∼15 mL/dL

  • Oxygen extraction is approximately 25%; it can also be estimated by:

  • SaO2 − SvO2

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Cardiac Output: CO = HR × SV Units: L/min
Cardiac Index: CI = CO/BSA in m2 Nl 3.6 – 6 L/min/m2

  • CI more used for children as it normalizes for size

Oxygen Delivery: DO2 = CO × CaO2 × 10

Oxygen Consumption: VO2 = CO × (CaO2 − CvO2) × 10

Oxygen Extraction Ratio: O2ER = VO2/DO2 = [(CaO2 − CvO2)/CaO2]

Pulmonary Vascular Resistance: PVR = (PAP − PAOP)/CO × 79.9 dynes*sec/cm5

Systemic Vascular Resistance: SVR = (MAP – RAP)/CO × 79.9 dynes*sec/cm5

  • If you don't multiply by 79.9, then use Woods units OR mmHg/L/min

  • PAP – Pulmonary artery pressure

  • PAOP – Pulmonary artery occlusion pressure

  • MAP – Mean arterial pressure

  • RAP – Right atrial pressure

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SVR Index: SVRI = SVR/BSA Nl: 800 to 1600 dyne-s/cm5/m2
PVR Index: PVRI = PVR/BSA Nl: 80 to 240 dyne-s/cm5/m2

Normal Pediatric Hemodynamic Variables - See Table 27-1

TABLE 27-1

Normal Pediatric Hemodynamic Parameters

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TABLE 27-1

Normal Pediatric Hemodynamic Parameters

Parameter Calculation Normal Values (Children)
Mean Arterial Pressure MAP = (SBP/3) + [(2 × DBP)/3]
Cardiac Index (CI) CI = CO/BSA 3.5–5.5 L/min/m2
Stroke Index SI = CI/HR 30–60 mL/m2
Oxygen Delivery DO2 = CI × CaO2 570–670 mL/min/m2
Fick Principle CI = VO2/(CaO2 − CvO2) Infant 160–180 mL/min/m2
Child 100–130 mL/min/m2
Mixed Venous O2 Saturation 65%–75%
Oxygen Extraction Ratio* OER = (SaO2 − SvO2)/SaO2 0.24–0.28
Oxygen Excess Factor* W = SaO2/(SaO2 − SvO2) 3.6–4.2
Systemic ...

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