Mean arterial pressure

The Mean arterial pressure, abbreviated MAD or MAP (of English. Mean arterial pressure ), describes in medicine the average of the blood pressure curve over time and is regarded as the most reliable parameter for organ perfusion. Standard values ​​are in the range between 70 and 105 mmHg.

Importance

The mean arterial pressure is between the systolic and diastolic arterial pressure. Since the blood pressure waveform having a narrow peak and a broad base in peripheral vessels, the arithmetic mean of systolic and diastolic pressure represented poorly actual pressure conditions over time. MAD is therefore used in the treatment as a measure to evaluate the organ perfusion and to ensure. This is particularly relevant in intensive care medicine in the care of critically ill patients a role, eg in catecholamine or sepsis. Also to calculate the cerebral perfusion pressure (CPP), which is used as a measure of cerebral blood flow, the MAD is used:

Or

With the ICP intracranial pressure and CVP is the central venous pressure. The higher value of the two is subtracted.

Determination

  • Invasive measurement: The direct determination of the mean pressure by invasive blood pressure measurement is the most accurate method dar. this purpose, the mean value of the derived arterial pressure curve is calculated. This method is mainly used in intensive care medicine and for intraoperative blood pressure measurement.
  • Oscillometric measurement: This method is used in automated blood pressure measuring devices used. To this end, the cuff pressure is released at specified intervals. In the range between systolic and diastolic pressure leads to an oscillation of the vessel wall (oscillation), which is transmitted to the cuff. The oscillations reach a maximum at the blood pressure corresponding to mean arterial pressure. The in oscillation and thus the MAD can thereby be determined with much higher accuracy than the end of the oscillation, which corresponds to the diastolic pressure.
  • Auscultatory measurement according to Riva- Rocci: during manual blood pressure measurement, the above-mentioned oscillations are perceived as Korotkoff sound by the examiner. Thus, the systolic and diastolic blood pressure value can be determined. The mittelere arterial pressure can be roughly estimated from the following formula for peripheral vessels:

Similarly, the MAD is very influenced by the degree of filling of the containers and the ratio of the diastolic and systolic arterial pressure varies in the same patient over time. Therefore, it is important to distinguish whether it is actually to the integral of the arterial pressure over time or whether it involves only one approximated from the measured systolic and diastolic values ​​calculated pressure at MAD.

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