Understanding Anesthesiology - The Global Regional Anesthesia ...

Pulse pressure
Pulse pressure is the difference between systolic and diastolic blood pressure. It is affected
by several factors, including intravascular volume and systolic vascular resistance (SVR).
For example, a high SVR will narrow the difference between systolic and diastolic blood
pressure, and therefore lower the pulse pressure. A low SVR will lower the diastolic blood
pressure (disproportionately to the systolic) and will cause a widened pulse pressure.
Imagine two unfortunate patients in the emergency room, each involved in a motor vehicle
accident, each with a systolic blood pressure of 110 mmHg. Patient A, who has a ruptured
spleen and is in the early stages of hypovolemic shock, will have a narrow pulse pressure
(BP 110/75), indicating that the sympathetic nervous system has been activated and that his
“normal” blood pressure is maintained due to high systemic vascular resistance.
Patient B has suffered a cervical spine injury and has a BP of 110/35, his wide pulse pressure
betraying the loss of sympathetic tone that has resulted from disruption of sympathetic outflow,
which exits the spinal column from T1-L2 to form the sympathetic chain.
Related Glossary Terms
Shock, Sympathetic nervous system
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Chapter 1 - Fluid Management