According to the American Heart Association, a blood pressure reading of 300/127 would be considered hypertensive crisis. A hypertensive crisis happens when the systolic reading (the top number) is higher than 180 and/or the diastolic reading (the bottom number) is higher than 120.
According to the American Heart Association, a normal blood pressure reading is lower than 120/80. While there is no specific number for low blood pressure, most experts say blood pressure is too low when it causes symptoms or drops suddenly. In general, though, low blood pressure can be considered anything under 90/60.
A blood pressure reading of 300/127 is pronounced "300 over 127." You may also see it written colloquially as 300/127 bp.
In a blood pressure reading of 300/127, 300 is called the systolic number and 127 is called the diastolic number. Systolic refers to the part of the cardiac cycle in which the heart contracts and pumps blood from the chambers into the arteries, and diastolic refers to the part of the cardiac cycle in which the heart relaxes and allows the chambers to fill with blood. You may also hear the systolic and diastolic numbers referred to as the top number and the bottom number.
Systolic and diastolic readings are measured in mmHg, which is a unit of pressure equal to the pressure that can support a column of mercury 1 millimeter high. Hg is the chemical symbol for mercury. For a blood pressure reading of 300/127, you would pronounce it "300 over 127 millimeters of mercury."
In a doctor's office, blood pressure is traditionally taken manually by a doctor or nurse with a sphygmomanometer. A sphygmomanometer is a medical instrument with an inflatable cuff and pressure meter or dial. The sphygmomanometer is placed snugly around the upper arm and is inflated by hand, and the doctor or nurse listens to the brachial artery with a stethoscope as they gradually reduce the pressure of the cuff. When the whooshing sound of blood is first heard through the stethoscope, the doctor or nurse makes note of the reading on the pressure meter. This indicates the systolic blood pressure reading. When the sound disappears, the reading on the pressure meter indicates the diastolic pressure reading.
Blood pressure can also be taken at home using a number of a digital devices. They typically consist of an inflatable cuff and digital display and simply work by placing the cuff around the upper arm and pressing a button, after which the cuff inflatess, deflates, and displays a reading. The most popular blood pressure machines for home use are made by Omron, Beurer, and Paramed, amongst many others.
Sphygmomanometer is pronounced sfig-moh-muh-'nah-mi-ter. Easy!
The following table shows related blood pressure readings because sometimes just one number can make all the difference.
Please note that if a field is blank, it's not an accident—it simply means a record doesn't exist for that particular blood pressure. This could be because going forward or backward would create a blood pressure reading that wouldn't make sense, or because that blood pressure simply doesn't exist in our records.
|← Prev systolic num||Next systolic num →|
|299/127 blood pressure||301/127 blood pressure|
|← Prev diastolic num||Next diastolic num →|
|300/126 blood pressure||300/128 blood pressure|
The information on this page is intended to be an educational reference and is not to be taken as medical advice. If you think you're having a hypertensive or hypotensive emergency, or if you're having any kind of medical emergency, please call 911 immediately.