About Cardiology Calculator
Cardiology Calculator application is used to calculate Body Surface Area, Cardiac Index, Cardiac Output, Fick Cardiac Output, Mean Arterial Pressure, Stroke Volume, Systemic Vascular Resistance and Pulmonary Vascular Resistance.
Body Surface Area:
In physiology and medicine, the body surface area (BSA) is the measured or calculated surface area of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Nevertheless, there have been several important critiques of the use of BSA in determining the dosage of medications with a narrow therapeutic index, such as chemotherapy.
Cardiac index (CI) is a haemodynamic parameter that relates the cardiac output (CO) from left ventricle in one minute to body surface area (BSA),
thus relating heart performance to the size of the individual.
The unit of measurement is litres per minute per square metre (L/min/m2).
The cardiac output is simply the amount of blood pumped by the heart per minute. Necessarily, the cardiac output is the product of the heart rate, which is the number of beats per minute, and the stroke volume, which is amount pumped per beat
Fick's Cardiac Output:
Cardiac output (Q) is the volume of blood being pumped by the heart, in particular by a ventricle in a minute. It is calculated by Fick principle.
Mean Arterial Pressure:
The Mean Arterial Pressure (MAP) is derived from a patient’s Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP).
MAP is often used as a surrogate indicator of blood flow and believed to be a better indicator of tissue perfusion than SBP as it accounts for the fact that two thirds of the cardiac cycle are spent in diastole.
Pulmonary Vascular Resistance:
Pulmonary vascular resistance (PVR) is similar to SVR except it refers to the arteries that supply blood to the lungs. If the pressure in the pulmonary vasculature is high, the right ventricle must work harder to move the blood forward past the pulmonic valve. Over time, this may cause dilation of the right ventricle, and require additional volume to meet the preload needs of the left ventricle.1
In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat (called end-systolic volume) from the volume of blood just prior to the beat (called end-diastolic volume). The term stroke volume can apply to each of the two ventricles of the heart, although it usually refers to the left ventricle. The stroke volumes for each ventricle are generally equal, both being approximately 70 mL in a healthy 70-kg man.
Systemic Vascular Resistance:
Systemic vascular resistance (SVR) reflects changes in the arterioles2, which can affect emptying of the left ventricle. For example, if the blood vessels tighten or constrict, SVR increases, resulting in diminished ventricular compliance, reduced stroke volume and ultimately a drop in cardiac output.1 The heart must work harder against an elevated SVR to push the blood forward, increasing myocardial oxygen demand. If blood vessels dilate or relax, SVR decreases, reducing the amount of left ventricular force needed to open the aortic valve. This may result in more efficient pumping action of the left ventricle and an increased cardiac output.2 Understanding SVR will help the bedside clinician treat a patient’s hemodynamic instability. If the SVR is elevated, a vasodilator such as nitroglycerine or nitroprusside may be used to treat hypertension. Diuretics may be added if preload is high. If the SVR is diminished, a vasoconstrictor such as norepinephrine, dopamine, vasopressin or neosynephrine may be used to treat hypotension. Fluids may be administered if preload is low.
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