Orthostatic vital signs have historically been obtained in the evaluation of children with syncope in the Emergency Department. Approximately 40% of people faint during their lives, half during adolescence. The peak age is fifteen. You will see these patients in the Pediatric Emergency Department. Do we really need to get them? Does looking at these numbers actually help us with diagnoses or dispositions? Let’s take a look.
How are orthostatic vitals performed?
This is the technique as described on the AHRQ website:
- Have the patient lie in a bed with the head flat for a minimum of 3 minutes
- Measure the blood pressure and the pulse while the patient is supine
- Instruct the patient to sit for 1 minute and if they are symptomatic allow them to return to a position of comfort.
- Have the patient stand, recording pulse and blood pressure with the forearm at heart level immediately and after standing for three minutes. If they are symptomatic (or hypotensive) allow them to return to a position of comfort.
What is abnormal?
By the numbers
- A decrease in systolic blood pressure ≥10 mmHg when going from one position to another
- An increase in heart rate ≥20 beats per minute when going from one position to another
- A dramatic increase in heart rare ≥40 beats per minute is consistent with postural orthostatic tachycardia syndrome (POTS)
- A blood pressure drop immediately after standing that resolves at three minutes is not orthostatic hypotension
Generally, as you will see, the actual symptoms a patient experiences upon positional changes are more important than the raw numbers. You could see an increase in HR by 25 when going from sitting to standing in an asymptomatic patient. Or you could see a decrease in SBP by 8 mmHG, but the patient looks like they are going to faint.
What is the evidence?
Unsurprisingly most of the evidence is in adults, who have conditions that children don’t, and whose physiology is largely unrelated and perhaps irrelevant. Children also present to the ED in varying states of duress; dehydrated, intoxicated, febrile and injured. All which effect the resting g heart rate. To date, I am not aware of any studies that state that a measurement of orthostatic vital signs, associated with a specific change in HR and/or BP, should result in a specific treatment, or correlates with a particular outcome. Here is a sampling of the types of studies out there.
This study of 23 healthy adolescents that used tilt tables and continuous HR and BP measurements found that there were widely variable changes in BP, some as great as 20 mmHG that were not associated with any symptoms. This study was also performed in a manner that is not relevant to the ED environment. The main conclusion was that dependent vascular tone plays a role in the changes seen. I’ve seen this study quoted when noting that healthy teens sometimes have “abnormal” orthostatic vitals without symptoms.
This prospective evaluation of 223 ED patients with syncope 16 and older did show that 31% of their subjects had orthostatic hypotension (≥20 mmHg drop in SBP) within 2 minutes of standing. They noted that “the recurrence of syncope was not related to the degree of orthostatic hypotension; however, the recurrence of dizziness and syncope as end-points was lower in patients with 20 mm Hg or greater systolic blood pressure reductions as compared with patients with lesser degrees of orthostatic blood pressure declines.” So they lend credence to the 20 mmHg change, and did note that age was a non-significant variable between symptomatic and asymptomatic patients. However, the mean age of patients was 51 years. No teen/yung adult subgroup analysis was done.
Another tilt table study, this time a case control in which the recruited controls were compared to patients that had been referred for orthostatic intolerance. The main goal was to compare adult POTS/OI guidelines to kids. They noted that “there was considerable overlap between the patient and control groups.” And that “42% of the normal controls had an HR increment of ≥30 beats per minute.” What does this mean? Again, largely not much for the ED since it was suing tilt tables in patients visiting a clinic who weren’t acutely ill or injured.
This large multi center cohort of 888 Chinese children with syncope noted that POTS was the most common etiology at 32%, though 31.5% had “unexplained syncope.” My take home is that a change in HR ≥30 is probably the only significant vital sign measurement related result you should note if you decide to get orthostatic vitals.
There are more, but again, no studies have looked at the utility of orthostatic vital signs in the Pediatric Emergency Department.
Anything else I should read?
This is an expert consensus review that tackles many of the questions in this post, with the opening salvo; recommendations on orthostatic intolerance come from adult consent and randomized control trials that “incompletely extend to children, for whom large trials and even small controlled studies are sparse.” It also goes into a lot more detail on POTS, treatment and controversies therein.
Take home points
I’m going to keep this short, and sweet, bullet point style!
- There is no evidence that orthostatic vital signs help in the diagnosis and management of syncope in the Pediatric Emergency Department, or in pediatric patients being evaluated in any Emergency Department
- They should not be a part of the routine “protocol” or “triage algorithm” for pediatric syncope
- They take several minutes to do and a nurse, MA, PCA’s time is better spent doing myriad other things that can help the patient
- Just stand the patient up and ask about and look for symptoms. You could use a HR increase ≥30 BPM to make the presumptive diagnosis of POTS, but not if the patient is dehydrated, which may be more likely in the ED
- Use the symptoms a patient feels as an impetus to start therapy – aggressive oral hydration or IV fluids – rather than the number
- And don’t even get me started on whether or not orthostatic vital signs tell you if a patient is dehydrated. You know what I’ll say about that one…
Shen et al. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation , 2017.