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Category Health & Nutrition

Cardiac Output (L/min) Range: 0.5 – 20.0 L/min

Height (cm) Range: 30 – 250 cm

Weight (kg) Range: 0.5 – 300 kg

BSA Formula Du Bois is the clinical default

Body Surface Area — m²

Cardiac Index — L/min/m²

Formula Used —

<2.0 2.0–2.4 2.5–4.0 4.1–5.0 >5.0

Metric	Value

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About

Cardiac Index normalizes Cardiac Output (CO) to body size by dividing it by Body Surface Area (BSA). Without this normalization, a CO of 4.5 L/min appears adequate for a 55 kg patient but may signal hypoperfusion in a 120 kg patient. Misinterpretation leads to delayed vasopressor titration, inappropriate fluid loading, or missed cardiogenic shock. This tool computes BSA via five validated formulas (Du Bois, Mosteller, Haycock, Gehan-George, Boyd) and returns CI with clinical interpretation against accepted hemodynamic thresholds. Note: all formulas assume standard body composition. Accuracy degrades in patients with significant edema, amputations, or morbid obesity (BMI > 40).

Formulas

The Cardiac Index is derived by normalizing Cardiac Output to body size:

CI = COBSA

Where CI = Cardiac Index (L/min/m²), CO = Cardiac Output (L/min), BSA = Body Surface Area (m²).

Body Surface Area formulas supported:

Du Bois (1916): BSA = 0.007184 × H^0.725 × W^0.425

Mosteller (1987): BSA = √H × W3600

Haycock (1978): BSA = 0.024265 × H^0.3964 × W^0.5378

Gehan-George (1970): BSA = 0.0235 × H^0.42246 × W^0.51456

Boyd (1935): BSA = 0.0003207 × H^0.3 × (W × 1000)^0.7285 − 0.0188 × log₁₀(W × 1000)

Where H = height in cm, W = weight in kg. The Du Bois formula remains the clinical default despite known underestimation in obese and pediatric populations. Mosteller is preferred in oncology for chemotherapy dosing. Haycock is validated for neonates and children.

Reference Data

Parameter	Low	Normal Range	High	Unit
Cardiac Index (CI)	< 2.0	2.5 - 4.0	> 5.0	L/min/m²
Cardiac Output (CO)	< 3.5	4.0 - 8.0	> 8.0	L/min
Stroke Volume (SV)	< 50	60 - 100	> 120	mL/beat
Heart Rate (HR)	< 60	60 - 100	> 100	bpm
Mean Arterial Pressure (MAP)	< 60	70 - 105	> 105	mmHg
SVR (Systemic Vascular Resistance)	< 800	800 - 1200	> 1200	dyn⋅s/cm⁵
PVR (Pulmonary Vascular Resistance)	< 100	100 - 250	> 250	dyn⋅s/cm⁵
PCWP (Pulmonary Capillary Wedge)	< 4	6 - 12	> 18	mmHg
CVP (Central Venous Pressure)	< 2	2 - 8	> 12	mmHg
BSA (Du Bois, adult avg.)	1.4	1.7 - 2.0	2.4	m²
Oxygen Delivery (DO₂)	< 800	950 - 1150	> 1200	mL/min
Oxygen Consumption (VO₂)	< 180	200 - 250	> 300	mL/min

Frequently Asked Questions

The Du Bois formula systematically underestimates BSA in patients with BMI > 35. Mosteller and Gehan-George show smaller deviations in obese cohorts. However, no formula is validated above BMI 50. For morbidly obese patients, consider using ideal body weight or adjusted body weight with clinical judgment rather than relying solely on calculated BSA.

A CI below 2.0 L/min/m² indicates cardiogenic shock or severe low-output state. Tissue perfusion is compromised, and organs (kidneys, liver, brain) may sustain ischemic injury. Immediate intervention - inotropes, vasopressors, or mechanical circulatory support - is typically required. A CI between 2.0 and 2.4 is borderline and warrants close monitoring with serial lactate and mixed venous oxygen saturation measurements.

Yes. A CI above 4.5-5.0 L/min/m² occurs in hyperdynamic states: sepsis (distributive shock), severe anemia, hyperthyroidism, arteriovenous fistulae, hepatic cirrhosis, and pregnancy. High CI in sepsis does not indicate adequate perfusion - microcirculatory dysfunction may still cause tissue hypoxia despite elevated global flow.

Thermodilution via pulmonary artery catheter measures CO by injecting cold saline and tracking temperature change. Tricuspid regurgitation causes recirculation of indicator, underestimating CO by 10-30%. Intracardiac shunts similarly distort the curve. Rapid injection (<4 seconds) of 10 mL iced saline and averaging three measurements within 10% reduces variability. Modern transpulmonary thermodilution (PiCCO) avoids right-heart catheterization but requires arterial and central venous access.

CI normal ranges differ by age. Neonates have higher CI (3.0-4.5 L/min/m²) due to higher metabolic demands. Use Haycock or Mosteller for BSA in children under 10 kg, as Du Bois was derived from adult data. Normal pediatric CI declines toward adult values by adolescence. Always interpret CI alongside clinical markers (capillary refill, urine output, lactate) in children.

CO is an absolute flow rate. A CO of 5.0 L/min perfuses a 1.5 m² body differently than a 2.2 m² body. BSA correlates with total capillary bed volume, organ mass, and oxygen demand. Indexing to BSA allows comparison across patients of different sizes and against standardized reference ranges derived from population studies.