A rapid, regular and thready pulse is most consistent with which condition?

• A. Shock and later stages of blood loss
• B. Fright
• C. High blood pressure
• D. Early stages of blood loss

Answer: (A)

Pulse quality reflects perfusion and circulating volume. A rapid pulse shows the heart is trying to compensate for decreased output, but a thready (weak) pulse means the stroke volume is low and peripheral perfusion is compromised, a pattern seen with shock from blood loss. As this progresses, the pulse remains rapid while becoming weaker, which fits shock and later stages of blood loss. In fright the pulse can be fast but is usually strong, and a high blood pressure tends to have a robust pulse rather than a thready one. Early blood loss may raise the heart rate without the pronounced weakness seen in more advanced hemorrhage.