Cardiac Index
Calculate cardiac index from cardiac output, height, and weight using the Haycock BSA formula. Free online CI calculator for cardiac function assessment with charts and clinical interpretation.
About This Calculator
The Cardiac Index (CI) Calculator helps healthcare professionals and patients assess cardiac function by normalizing cardiac output for body size. Cardiac index is calculated by dividing cardiac output (CO) by body surface area (BSA), providing a more accurate measure of cardiac performance that accounts for individual patient size. This parameter is essential in intensive care medicine, cardiology, and perioperative monitoring.
The calculation uses the Haycock formula for body surface area: BSA = 0.024265 × height^0.3964 × weight^0.5378, where height is in centimeters and weight is in kilograms. The cardiac index is then calculated as CI = CO / BSA, expressed in liters per minute per square meter (L/min/m²). The normal cardiac index range is 2.5 to 4.0 L/min/m², with values below 2.0 indicating cardiogenic shock.
Regional Notes
India: In Indian clinical practice, cardiac index monitoring is commonly performed in cardiac ICUs and during cardiac surgeries. The normal range (2.5–4.0 L/min/m²) applies uniformly, though BSA formula choice may vary between institutions (Haycock, Mosteller, or Du Bois).
United States: In the US, the Haycock formula is widely used in pediatric populations, while the Mosteller formula is common in adult medicine. Cardiac index is a standard parameter in critical care guidelines from the Society of Critical Care Medicine (SCCM) and the American College of Cardiology (ACC).
United Kingdom: In the UK, NICE guidelines recommend cardiac index monitoring in high-risk surgical patients and those in critical care. The National Health Service (NHS) uses CI alongside other hemodynamic parameters for goal-directed therapy in sepsis management.
Frequently Asked Questions
What is cardiac index and how is it calculated?
Cardiac index (CI) normalizes cardiac output for body size by dividing cardiac output by body surface area (CI = CO / BSA). BSA is calculated using the Haycock formula: BSA = 0.024265 × height^0.3964 × weight^0.5378. The normal cardiac index range is 2.5 to 4.0 L/min/m².
What is a normal cardiac index range?
The normal cardiac index range is 2.5 to 4.0 L/min/m². A value below 2.0 L/min/m² is highly indicative of cardiogenic shock and requires immediate medical attention. Values between 2.0 and 2.5 L/min/m² suggest reduced cardiac output.
Can I calculate cardiac index without cardiac output?
Cardiac output can be calculated as stroke volume (mL) multiplied by heart rate (bpm), then divided by 1000 to convert to L/min. For example, if stroke volume is 70 mL and heart rate is 64 bpm, cardiac output = 70 × 64 / 1000 = 4.48 L/min.
What is the Haycock formula for BSA?
The Haycock formula calculates body surface area (BSA) as 0.024265 × height(cm)^0.3964 × weight(kg)^0.5378. It is one of the most commonly used BSA formulas in clinical settings for normalizing physiological parameters like cardiac output.
How accurate is this cardiac index calculator?
This calculator uses standard medical formulas (Haycock for BSA) and provides clinically relevant interpretation. Results should always be verified by a healthcare professional and are not a substitute for professional medical diagnosis.
What does a low cardiac index mean?
A low cardiac index (< 2.5 L/min/m²) indicates the heart may not be pumping enough blood to meet the body's oxygen demands. Values under 2.0 L/min/m² suggest cardiogenic shock, a life-threatening condition that requires emergency medical treatment.
Is cardiac index measured differently in children?
Yes, children have higher normal cardiac index values due to their higher metabolic rates. Normal ranges vary by age: neonates (2.5–4.2 L/min/m²), infants (3.0–4.5 L/min/m²), children (3.0–4.0 L/min/m²), and adolescents approach adult values (2.5–4.0 L/min/m²).
How is cardiac index used in intensive care?
Cardiac index is a key hemodynamic parameter monitored in ICUs and cardiac intensive care units. It guides fluid resuscitation, vasopressor therapy, and inotropic support in critically ill patients. A pulmonary artery catheter (Swan-Ganz) is often used for direct measurement.