Mean arterial pressure

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The mean arterial pressure (MAP) is a term used in medicine to describe an average blood pressure in an individual.[1] It is defined as the average arterial pressure during a single cardiac cycle.

Calculation[edit]

Total Peripheral Resistance (TPR) is represented mathematically by the formula:

R = ΔP/Q[2]

R is TPR. ΔP is the change in pressure across the systemic circulation from its beginning to its end. Q is the flow through the vasculature (equal to cardiac output)

In other words:

Total Peripheral Resistance = (Mean Arterial Pressure - Mean Venous Pressure) / Cardiac Output

Therefore, Mean arterial pressure can be determined from:[3]

MAP = (CO \cdot SVR) + CVP

where:

Estimation[edit]

At normal resting heart rates MAP can be approximated using the more easily measured systolic and diastolic pressures, SP and DP:[4][5][6]

MAP \simeq DP + \frac{1}{3}(SP - DP)

or equivalently

MAP \simeq \frac{2}{3}(DP) + \frac{1}{3}(SP)

or equivalently

MAP \simeq \frac{(2 \times DP) + SP}{3}

or equivalently

MAP \simeq DP + \frac{1}{3}PP

where PP is the pulse pressure, SP-DP

At high heart rates MAP is more closely approximated by the arithmetic mean of systolic and diastolic pressures because of the change in shape of the arterial pressure pulse.

Clinical significance[edit]

MAP is considered to be the perfusion pressure seen by organs in the body.

It is believed that a MAP that is greater than 60 mmHg is enough to sustain the organs of the average person. MAP is normally between 70 and 110 mmHg.[7] MAP may be used similarly to Systolic blood pressure in[clarification needed] for target blood pressure. Both have been shown advantageous targets for sepsis, trauma, stroke, intracranial bleed, and hypertensive emergencies.[8]

If the MAP falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become hypoxic, a condition called ischemia.

See also[edit]

References[edit]

  1. ^ Zheng L, Sun Z, Li J, et al. (July 2008). "Pulse pressure and mean arterial pressure in relation to ischemic stroke among patients with uncontrolled hypertension in rural areas of China". Stroke 39 (7): 1932–7. doi:10.1161/STROKEAHA.107.510677. PMID 18451345. 
  2. ^ Total peripheral resistance, Wikipedia
  3. ^ Cardiovascular Physiology Concepts: Mean Arterial Pressure, Richard E. Klabunde, Ph.D
  4. ^ Physiology at MCG 3/3ch7/s3ch7_4
  5. ^ Cardiovascular Physiology (page 3)
  6. ^ http://www.clinicalreview.com Physiology Review
  7. ^ impactEDnurse (May 31, 2007). "mean arterial pressure". impactednurse.com. Retrieved 2010-12-25. 
  8. ^ Magder SA (2014). "The highs and lows of blood pressure: toward meaningful clinical targets in patients with shock.". Crit Care Med. 42 (5): 1241–51. PMID 24736333. 

External links[edit]