Orthostatic Vital Signs
This discussion at Girlvet's reminded me of how I used to explain the interpretation of orthostatic vital signs to my medical students and residents.
Why do we obtain orthostatic vital signs? In a dizzy patient, we want to see if their current hemodynamic status accounts for their dizziness. In elderly patients or other patients we suspect of having neurogenic orthostasis, the evaluation of orthostatic vital signs allows us to measure their hemodynamic response to standing. In dehydrated patients, we want to see if they have been adequately rehydrated. Of course, many medications may blunt the orthostatic changes in vital signs, but important information can still be gathered by their measurement.
Classically, we were taught that a drop in systolic BP by more than 20 points and/or an increase in pulse rate of more than 20 beats per minute after a change from supine to standing suggested an abnormal hemodynamic status. If there is only a pulse increase but no drop in blood pressure, the test is less significant. If there is a drop in blood pressure without an increase in pulse, one should consider whether medications might be contributing to this pattern.
In the elderly patient, abnormal orthostatic VS in the absence of dehydration may not be affected much by the administration of fluids due to underlying disturbances in blood pressure regulation, and alternate therapies may be more appropriate if the patient is symptomatic.
In the dehydrated patient, the presence of orthostasis, particularly when symptomatic, suggests inadequate rehydration. Orthostasis can also be an important early sign of occult GI bleeding.
If an abnormality in orthostatic vital signs is discovered, the significance must be placed into context. The greater the change in orthostatic vital signs, the more likely there is a problem that needs to be addressed.
Despite modern medicine's overreliance upon blood tests or radiographic imaging studies for the diagnosis of various maladies, the measurement of orthostatic vital signs is quick, cheap, easy, and still valuable after all these years.