Hypotension [Neurosurgery Wiki]

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====== Hypotension ======

see [[Shock]]
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**ABC [[Stabilization]]:**
  * **[[Airway]]**: Intubate if GCS ≤ 8.
  * **[[Breathing]]**: Maintain SpO₂ > 94%.
  * **[[Circulation]]**: Avoid [[hypotension]] (SBP < 90 mmHg).
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Hypotension is low [[blood pressure]], especially in the [[artery]] of the systemic [[circulation]].

Hypotension is generally considered systolic blood pressure less than 90 millimeters of mercury (mm Hg) or diastolic less than 60 mm Hg.

However, in practice, blood pressure is considered too low only if noticeable symptoms are present.

Hypotension is the opposite of hypertension, which is high blood pressure. It is best understood as a physiological state, rather than a disease. It is often associated with shock, though not necessarily indicative of it.

For some people who exercise and are in top physical condition, low blood pressure is a sign of good health and fitness.

For many people, excessively low blood pressure can cause dizziness and fainting or indicate serious heart, endocrine or neurological disorders. Severely low blood pressure can deprive the brain and other vital organs of oxygen and nutrients, leading to a life-threatening condition called shock.
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Chesnut et al. prospectively studied the [[outcome]] from [[severe head injury]] (GCS score < or = 8) in 717 cases in the Traumatic Coma Data Bank. They investigated the impact on the outcome of [[hypotension]] (SBP < 90 mm Hg) and [[hypoxia]] (Pao2 < or = 60 mm Hg or apnea or cyanosis in the field) as secondary brain insults, occurring from injury through resuscitation. Hypoxia and hypotension were independently associated with significant increases in morbidity and mortality from severe head injury. Hypotension was profoundly detrimental, occurring in 34.6% of these patients and associated with a 150% increase in mortality. The increased morbidity and mortality related to severe trauma to an extracranial organ system appeared primarily attributable to associated hypotension. Improvements in trauma care delivery over the past decade have not markedly altered the adverse influence of hypotension. Hypoxia and hypotension are common and detrimental secondary brain insults. Hypotension, particularly, is a major determinant of the outcome of severe head injury. [[Resuscitation]] protocols for brain-injured patients should assiduously avoid hypovolemic shock on an absolute basis
((Chesnut RM, Marshall LF, Klauber MR, Blunt BA, Baldwin N, Eisenberg HM, Jane
JA, Marmarou A, Foulkes MA. The role of secondary brain injury in determining
outcome from severe head injury. J Trauma. 1993 Feb;34(2):216-22. PubMed PMID:
8459458.
)).