A narrow pulse pressure.

A narrow pulse pressure, which is the difference between the systolic and diastolic, is an early indication of shock. Look for hypovolemia or decreased cardiac output. Often the systolic pressure will start to fall as cardiac output decreases. A patient who is hypovolemic, or a patient who has decreased cardiac output from an MI, will exhibit a decrease in the systolic pressure.

The body's compensatory mechanism and response to decreased cardiac output is to stimulate the sympathetic nervous system. This will cause vasoconstriction and result in a rise in the diastolic pressure causing a narrowed pulse pressure.

A narrow pulse pressure in shock is consistent with hypovolemic and cardiogenic causes. Septic shock will cause a widened pulse pressure. One way to differentiate shock in your patients is to look at the pulse pressure. A narrow pulse pressure associated with hypovolemia would be hypovolemic. A narrow pulse pressure associated with volume overload would be cardiogenic. A wide pulse pressure associated with hypovolemic would be septic.

Watch for those changes and watch for those trends in the patient's vital signs. You may see the patient's blood pressure and you may see that pulse pressure narrowing before you start to see any other symptoms that your patient is developing shock.

Type--Pulse Pressure--Volume Hypovolemic--Narrow--Low Cardiogenic--Narrow--High Septic--Wide--Low David W. Woodruff, MSN, RN, CNS, CEN President, Ed4Nurses,