OEM MAXNIBP® What is Blood Pressure? Blood pressure is the pressure of the circulating blood against the walls of the arteries. The heart acts as a pump, which moves and maintains the blood flow throughout the body. Blood pressure is dependent upon the energy of the heart action, elasticity of the arterial walls and blood volume and viscosity. Anything that affects heart rate will affect blood pressure. Blood pressure is usually measured in millimeters of mercury (mmHg). You will see numbers written like this: B/P 120/80, MAP 93. Systolic Pressure The upper number, 120 in this example, is the systolic pressure. This is the maximum pressure present in the artery and occurs during systole when the ventricles contract and the pulse of blood is ejected into the aorta. The systolic pressure becomes higher as the blood travels away from the heart. This reading is critical because your system requires a minimum amount of pressure to get blood to your brain and other body parts, but too much pressure can cause damage to the vessels. Diastolic Pressure The lower number, 80 in this example, is the diastolic pressure. This is the amount of pressure present in the system between beats. The aortic valve is closed and the left ventricle is in diastole, dilated and filling with blood. Too high a pressure can cause damage to the artery walls; too low a pressure will prevent the myocardium (heart muscle) from getting the blood it needs. Diastolic pressure decreases slightly as the blood travels away from the heart. The diastolic pressure will increase with age as the arteries become less elastic and do not relax as much. Mean Arterial Pressure MAP is an indicator of the cardiovascular status and tissue perfusion. It is a good indicator for trending data because it does not fluctuate as widely under normal circumstances. In an invasive measurement, MAP is a calculated number based on the Systolic and the Diastolic Pressures. In an oscillometric measurement, MAP is the cuff pressure at which the maximum pressure pulse amplitude is obtained. References: 1. Geddes LA, ME, PhD, Handbook of Blood Pressure Measurement, Humana Press, Clifton NJ, 1991. 2. Forster FK and Turney D, Journal of Biomechanical Engineering, Vol. 108, pp 359-364, Nov 1986. For more information: Toll Free: 800.227.4414 Local: 203.488.6056 Ask for OEM Product Manager CAS Medical Systems Inc. 44 E Industrial Rd, Branford, CT 06405 USA www. CASMED.com MAXNIBP What is BP Rev 0.2 5102010