Is a Mean Arterial Pressure of 28 mmHg Abnormal?
Yes, a MAP of 28 mmHg is critically and life-threateningly low, representing severe shock with imminent risk of multi-organ failure and death.
Understanding Normal MAP Values
A MAP of 28 mmHg is approximately 37 mmHg below the minimum threshold required to maintain organ perfusion. 1
- Normal MAP in healthy individuals averages around 70-100 mmHg, with the critical lower threshold for organ autoregulation being 65 mmHg 1
- Below 65 mmHg, organ blood flow becomes linearly dependent on arterial pressure as autoregulatory mechanisms fail 1
- The kidney, which receives the second-highest blood flow relative to its mass, requires adequate perfusion pressure to maintain function, and a MAP of 28 mmHg would result in acute kidney injury 1
Clinical Significance of MAP 28 mmHg
This represents profound circulatory collapse requiring immediate resuscitation:
- Recent data demonstrates a U-shaped mortality relationship with MAP in septic patients, with the lowest mortality occurring between 70-82 mmHg 2
- MAP below 70 mmHg shows progressively increasing mortality risk, with each mmHg decrease associated with higher odds of death 2
- At 28 mmHg, tissue hypoperfusion is universal, with inadequate oxygen delivery to all vital organs including brain, heart, kidneys, and splanchnic circulation 1
Immediate Clinical Implications
A patient with MAP 28 mmHg requires emergent intervention:
- The Surviving Sepsis Campaign establishes MAP ≥65 mmHg as the minimum initial resuscitation target 1
- At 28 mmHg, expect absent or severely diminished peripheral pulses, altered mental status, oliguria/anuria, and profound lactic acidosis 1
- This pressure is incompatible with consciousness and organ viability beyond minutes to hours 1
Comparison to Critical Thresholds
To contextualize how abnormal 28 mmHg is:
- Standard resuscitation targets: MAP ≥65 mmHg for most critically ill patients 1
- Patients with chronic hypertension require MAP ≥70 mmHg to maintain renal perfusion 1
- Even the lowest acceptable MAP in elderly patients (who may tolerate permissive hypotension) is 60-65 mmHg 1
- A MAP of 28 mmHg is 32-37 mmHg below even these most permissive targets 1
Urgent Management Required
Immediate resuscitation priorities at MAP 28 mmHg:
- Initiate rapid fluid resuscitation with crystalloids while simultaneously starting vasopressor support 1
- Norepinephrine is first-line vasopressor, titrated aggressively to achieve MAP ≥65 mmHg 1
- Monitor lactate clearance, urine output, and mental status as markers of adequate tissue perfusion beyond MAP alone 1
- Investigate and treat underlying cause (septic shock, cardiogenic shock, hemorrhagic shock, anaphylaxis) 1