Lets talk about aterial lines and MAP

  Let's talk about arterial lines

 

Arterial monitoring is the gold standard for blood pressure monitoring in the critical care patient.
For a quick snapshot of the waveform interpretation see the awesome article by LIFL https://litfl.com/arterial-line-and-pressure-transducer/ 


 


MAP, or mean arterial pressure, is defined as the average pressure in a patient’s arteries during one cardiac cycle. It is considered as a better indicator of perfusion to vital organs than systolic blood pressure (SBP). True MAP can only be determined by invasive monitoring;however it can also be calculated using a formula. Critical . Care nurses should be able to get a rough MAP figure manually by using the formula shown below.

  MAP = SBP + 2 (DBP)
                3

Systolic BP + 2x Diastolic BP divided by 3.  

Systole is the time when the ventricles are contracting and diastole is the relaxation time. In normal condition, the systole phase takes about half the time the diastole takes. In other words, diastole takes twice as longer as systole.
 
This explains why we cannot just add systolic blood pressure and diastolic blood pressure and divide it with 2. The time each takes is different.