Hypotension and Shock

1

What is hypotension?

Decreased blood pressure relative to a person’s baseline blood pressure.

Hypotension is a systolic blood pressure less than 90 mm Hg or a mean arterial pressure of less than 60 mm Hg for a duration of at least 30 minutes. Another definition is a decrease in a person’s baseline blood pressure of 30%. The absolute point of hypotension varies between individuals. A normal adult whose systolic blood pressure is chronically 90 mm Hg may have no symptoms. Another adult with chronic hypertension, whose chronic systolic blood pressure is 185 mm Hg, may be symptomatic at 120 mm Hg. The blood pressure below which a person becomes symptomatic is hypotension.

2

What is needed for adequate blood pressure?

A closed, functional, filled cardiovascular system with the body in homeostasis.

Blood pressure is the result of multiple, interactive components. The vascular structures, arteries, arterioles, capillaries, venioles, and veins are intact and without significant leaks. There is an adequate and appropriate volume of blood and blood components to fill the vascular structures. Heart function must be sufficient to propel the blood forward through the body with total volume return for redistribution. Renal function balances fluids, electrolytes, and pH while removing wastes. Neurohormonal oversight and management detect and adjust the systems (e.g., vascular tone, heart rate, respiratory rate, glomerular filtration rate, gluconeogenesis) to control the variables that can affect the homeostatic state of the body.

3