Postural Vital Signs

Question#: 653

Question:

When attending a witnessed syncope where the patient is now conscious, alert, and oriented, should the first set of vitals be taken before standing them? In what cases would you prefer to stand them first?

Answer:

With respect to the syncopal patient, there is a wide range of differentials that may be the cause of said syncopal event.

Within our training, we have many tools that can help rule in/rule out the differentials, and it’s important to use them often.

As an example, it would be prudent to do a 12-lead on patient who has a syncopal event.

Despite the test at our disposal, it’s important to acknowledge our limitations, especially in the context that approximately 34% of syncopal events have no clear etiology.

Given the wide range of differentials, there are a couple of mnemonics that can potentially help narrow into a diagnosis. There’s the HEAD, HEART, VeSSELS and the SVNCOPE mnemonics that are most frequently used.

HEAD, HEART, VeSSELS
Hypoxia/hypoglycemia
Epilepsy
Anxiety
Dysfunctional brainstem,

Heart attack
Embolism (PE)
Aortic obstruction
Rhythm disturbance
Tachycardia

Vasovagal
Situational
Subclavian steal
ENT
Low SVR
Sensitive carotid sinus

SVNCOPE
Situational
Vasovagal
Neurogenic
Cardiogenic
Orthostatic
Psychogenic
Endocrine

So, as a blanket statement, given the wide range of potential pathologies, it’s not necessary that the first set of vital signs is taken supine.

As you’re alluding to, there is a patient population that may benefit from taking postural vitals signs: those that you’re concerned about orthostatic hypotension.

Orthostatic hypotension can be asymptomatic or symptomatic. When autonomic reflexes are impaired or intravascular volume is markedly depleted, there’s a significant reduction in blood pressure that occurs upon standing. Orthostatic hypotension is diagnosed by comparing blood pressure readings in the supine and standing positions. The threshold of change for orthostatic hypotension is:

• A reduction of 20 mmHg or more in systolic pressure

• A reduction of 10 mmHg or more in diastolic pressure

When this happens, the heart rate typically rises to compensate for a postural reduction in blood pressure

In order to correctly perform postural vital signs, the blood pressure is taken initially after a five-minute period of supine rest then again after the patient has been standing for two to five minutes. As you can appreciate, this rarely occurs properly in the prehospital environment.

To summarize, as a blanket statement, given the wide range of potential pathologies, it’s not necessary that the first set of vital signs is taken supine. There may be a small subset of patients that may benefit from postural vital signs, but there’s a specific technique that is rarely performed properly in the prehospital environment.

References:
https://litfl.com/syncope/
https://www.uptodate.com/contents/mechanisms-causes-and-evaluation-of-orthostatic-hypotension?search=orthostatic%20hypotension&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
https://canadiem.org/tiny-tips-svncope-for-syncope/