This is the average pressure that is driving the blood flow through the circulation, through the tissues and back to the heart.
The Mean Arterial Pressure or MAP = CO x SVR (+ CVP).
- CO = cardiac output
- SVR = systemic vascular resistance
- CVP = central venous pressure
To get the MAP, add the SBP to twice the diastolic pressure, and divide by 3.
Think about the factors involved in maintaining an effective arterial circulation.
That’s all you need to know.
Put your finger on the pulse.
The radial pulse is palpable where the SBP is > 80 mmHg.
The femoral pulse will still be palpable when the systolic BP is 70-80 mmHg.
The carotid pulse will remain palpable where the SBP is 60-70 mmHg.
It goes without saying that the MAP is inadequate if (in a conscious patient) you cannot feel the radial pulse.
Your aim is for a MAP of 65-75 mmHg.
At your disposal are elements to manipulate effectively essentially the stroke volume.
You do this by:
- giving fluid: to increase preload (Starling curve)
- giving vasopressors: to increase afterload (SVR)
- starting inotropes: to increase force of contraction
