{
  "id": "cardiac-output",
  "version": "7cf9ad114f01",
  "status": "published",
  "name": "Cardiac Output Calculator",
  "question": "What is the cardiac output?",
  "summary": "Works out cardiac output from heart rate and stroke volume, or by the Fick principle from oxygen use and blood oxygen levels, with the cardiac index over the body surface area.",
  "category": "health",
  "subcategory": "clinical",
  "url": "https://www.acalculator.org/health/cardiac-output-calculator",
  "markdown": "https://www.acalculator.org/health/cardiac-output-calculator.md",
  "kind": "function",
  "method": "CO = HR × SV ÷ 1,000 (L/min). Fick: CO = VO2 ÷ ((CaO2 − CvO2) × 10), with O2 content = 1.34 × Hb × saturation + 0.003 × PO2 (mL/dL). CI = CO ÷ BSA, BSA = √(cm × kg ÷ 3,600) (Mosteller).",
  "assumptions": [
    "The Fick method needs a mixed venous sample from the pulmonary artery and a measured or estimated oxygen use.",
    "Hemoglobin carries 1.34 mL of oxygen per gram when fully saturated; plasma carries 0.003 mL/dL per mmHg.",
    "The page shows the arithmetic for measured values. It is not a measurement and not a diagnosis."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "method": {
        "title": "Method",
        "description": "Heart rate × stroke volume, or the Fick principle from oxygen use and oxygen content.",
        "type": "string",
        "enum": [
          "hrsv",
          "fick"
        ]
      },
      "hr": {
        "title": "Heart rate (beats/min)",
        "description": "Heart rate in beats a minute, 20 to 250.",
        "type": "number",
        "minimum": 20,
        "maximum": 250
      },
      "sv": {
        "title": "Stroke volume (mL)",
        "description": "Blood pumped in one beat, in mL, 5 to 250.",
        "type": "number",
        "minimum": 5,
        "maximum": 250
      },
      "vo2": {
        "title": "Oxygen use, VO2 (mL/min)",
        "description": "Oxygen consumption in mL a minute, measured or estimated, 50 to 2,000.",
        "type": "number",
        "minimum": 50,
        "maximum": 2000
      },
      "hb": {
        "title": "Hemoglobin (g/dL)",
        "description": "Hemoglobin in g/dL, 3 to 25.",
        "type": "number",
        "minimum": 3,
        "maximum": 25
      },
      "sao2": {
        "title": "Arterial saturation, SaO2",
        "description": "Arterial oxygen saturation, 50% to 100%.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 50,
        "maximum": 100
      },
      "svo2": {
        "title": "Mixed venous saturation, SvO2",
        "description": "Mixed venous oxygen saturation (pulmonary artery blood), 10% to 100%.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 10,
        "maximum": 100
      },
      "pao2": {
        "title": "Arterial PO2 (mmHg)",
        "description": "Arterial oxygen pressure in mmHg, 20 to 700.",
        "type": "number",
        "minimum": 20,
        "maximum": 700
      },
      "pvo2": {
        "title": "Mixed venous PO2 (mmHg)",
        "description": "Mixed venous oxygen pressure in mmHg, 10 to 100.",
        "type": "number",
        "minimum": 10,
        "maximum": 100
      },
      "height": {
        "title": "Height",
        "description": "Height, for the body surface area: 50 cm to 250 cm.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0.5,
        "maximum": 2.5
      },
      "weight": {
        "title": "Weight",
        "description": "Weight, for the body surface area: 2 kg to 300 kg.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "exclusiveMinimum": 2,
        "maximum": 300
      }
    }
  },
  "outputs": {
    "co": {
      "label": "Cardiac output (L/min)",
      "description": "Litres of blood the heart pumps a minute, to 2 decimals.",
      "format": "number"
    },
    "ci": {
      "label": "Cardiac index (L/min/m²)",
      "description": "Cardiac output ÷ body surface area, to 2 decimals.",
      "format": "number"
    },
    "bsa": {
      "label": "Body surface area (m²)",
      "description": "Mosteller: √(height cm × weight kg ÷ 3,600), to 2 decimals.",
      "format": "number"
    },
    "avDiff": {
      "label": "Arterial-venous O2 difference (mL/dL)",
      "description": "Fick only: arterial minus mixed venous oxygen content, to 2 decimals.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "method": "hrsv",
      "hr": 70,
      "sv": 70,
      "vo2": 250,
      "hb": 15,
      "sao2": 98,
      "svo2": 75,
      "pao2": 95,
      "pvo2": 40,
      "height": "5ft10in",
      "weight": "170 lb"
    },
    "outputs": {
      "co": 4.9,
      "ci": 2.5108693835553755,
      "bsa": 1.9515152927077517
    },
    "text": "The cardiac output is 4.9 L/min, a cardiac index of 2.51 L/min/m²."
  },
  "examples": [
    {
      "given": {
        "method": "hrsv",
        "hr": 70,
        "sv": 70,
        "height": 1.778,
        "weight": 77.1107029
      },
      "expect": {
        "co": 4.9,
        "bsa": 1.9515152927077517,
        "ci": 2.5108693835553755
      },
      "source": "Demir 2025 and Mosteller 1987: CO = HR × SV = 70 × 70 = 4,900 mL/min = 4.9 L/min; Mosteller BSA √(177.8 × 77.1107029 ÷ 3600) = 1.952 m²; CI = 4.9 ÷ 1.952 = 2.51 (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "hrsv",
        "hr": 60,
        "sv": 80,
        "height": 1.8,
        "weight": 80
      },
      "expect": {
        "co": 4.8,
        "bsa": 2,
        "ci": 2.4
      },
      "source": "60 × 80 = 4.8 L/min; √(180 × 80 ÷ 3600) = √4 = 2 m²; 4.8 ÷ 2 = 2.4 (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "fick",
        "vo2": 250,
        "hb": 15,
        "sao2": 98,
        "svo2": 75,
        "pao2": 95,
        "pvo2": 40,
        "height": 1.8,
        "weight": 80
      },
      "expect": {
        "co": 5.221386800334169,
        "avDiff": 4.788,
        "bsa": 2,
        "ci": 2.6106934001670843
      },
      "source": "Fick with the Nebout 2012 oxygen content: CaO2 = 1.34 × 15 × 0.98 + 0.003 × 95 = 19.983; CvO2 = 1.34 × 15 × 0.75 + 0.003 × 40 = 15.195; difference 4.788 mL/dL; 250 ÷ 47.88 = 5.22 L/min (hand calculation in content.mdx)"
    }
  ],
  "sources": [
    "Demir ZA, Bingül ES, Dost B, et al. Foundations and advancements in hemodynamic monitoring: Part I, elements of hemodynamics. Turk J Anaesthesiol Reanim. 2025;53(3):87-97. https://doi.org/10.4274/tjar.2025.251925 (open at https://pmc.ncbi.nlm.nih.gov/articles/PMC12123657/, retrieved 2026-10-05). Cited for CO = HR × SV, the Fick equation, and the cardiac index; it uses 1.39 and 0.0031 for oxygen content, and this page uses the 1.34 and 0.003 of Nebout 2012.",
    "Nebout S, Pirracchio R, et al. Should we monitor ScVO2 in critically ill patients? Cardiol Res Pract. 2012;2012:370697 (oxygen content CaO2 = Hb × 1.34 × SaO2 + 0.003 × PaO2). https://doi.org/10.1155/2012/370697 (open at https://pmc.ncbi.nlm.nih.gov/articles/PMC3177360/, retrieved 2026-10-05)",
    "Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. https://doi.org/10.1056/NEJM198710223171717 (retrieved 2026-10-05)"
  ],
  "related": [],
  "changelog": [
    {
      "date": "2026-10-05",
      "note": "Published after this site's editorial review against the cited sources (no clinician review); the page notices say so."
    }
  ]
}