Postural hypotension in patients with syncope

Arch Intern Med 2009 PMID: 19636031

The authors report that in 2106 consecutive patients 65 years or older admitted for syncope, "Postural blood pressure (BP) recording, performed in only 38% of episodes, had the highest yield with respect to affecting diagnosis (18%-26%) or management (25%-30%) and determining etiology of the syncopal episode (15%-21%)."

• The lower percentages are based on 'strict criteria' for abnormal changes:
  
  
  • drop in systolic BP of at least 20 mm Hg
  • or
  • drop in diastolic BP of at least 10 mm Hg
• The higher percentages are based on 'loose criteria' for abnormal changes:
  
  
  • drop in systolic or diastolic BP of at least 10 mm Hg
  • or
  • systolic BP drop to 90 mm Hg or lower
    
  
  

A systematic review of postural blood pressure measurements has been published by the Rational Clinical Examination (McGee S, Abernethy WB, Simel DL The rational clinical examination. Is this patient hypovolemic? JAMA 1999;281 (11):1022-9. DOI:10.1001/jama.281.11.1022 PMID: 10086438 ) Their meta-analysis concluded that the following changes may occur in normal, euvolemic adults:

• Pulse increase:11 (95CI: 9-13)
  
• Systolic blood pressure drop: 4 (95CI: 2 - 6)
• Diastolic blood pressure drop: 5 (95CI:3 - 8)

Based on the Rational Clinical Examination review, which reveals how difficult it is to interpret orthostatic vital signs and that we cannot simply dichotomize the results into normal and abnormal, I think the strict criteria are better. Even with these criteria, orthostatic vital signs was the most important part of the evaluation for syncope.

This has been added to http://en.citizendium.org/wiki/Syncope and http://wiki.medpedia.com/Clinical:Syncope.

Citation:
Mendu ML, McAvay G, Lampert R, Stoehr J, & Tinetti ME (2009). Yield of diagnostic tests in evaluating syncopal episodes in older patients. Archives of Internal Medicine, 169 (14), 1299-305 PMID: 19636031