Hypovolaemia: small changes in vital signs did not exclude large blood loss.

Clinical bottom line (level 2a)

  1. Patients with a postural pulse rise of more than 30 beats/minute or severe postural dizziness on standing from supine were very likely to have lost at least 630 ml of blood (LR+49) . If these signs are absent, large blood loss was much less likely (LR+0.030) .
  2. Patients with postural pulse rise of more than 30 beats/minutes or severe postural hypotension on sitting from supine were very likely to have lost at least 630 ml of blood (LR+39) . Absence of these signs on sitting up made large blood loss less likely (LR+0.22) .
  3. Patients with supine hypotension (systolic < 95 mmHg) or supine tachycardia were more likely to have lost at least 630 ml of blood.
  4. Absence of supine tachycardia or hypotension did not exclude blood loss of at least 630 ml.
McGee et al: Journal of the American Medical Association 1999; 281 (11): 1022-1029
Expires October 2003

The study

Systematic review of all articles of
  • Patients: suspected hypovolaemia
  • Intervention: clinical features
  • Outcome: hypovolaemia


    • Articles found in English using Medline, 1966 to 1997 (search terms: 3 search strategies based on dehydration, hypotension, orthostatic, heart rate, tilt-table test ) and reviewing bibliographies of retrieved articles and textbooks on physical diagnosis.

    Selection criteria: see above
    Appraisal criteria: graded using set criteria by 2 independent reviewers
    Articles excluded if:
    • studies on children or infants


    9 studies of normovolaemic patients who had phlebotomy of 500 - 1000 ml.
    Studies were not tested for homogeneity - a random effects model was used to combine data.

    The evidence


    diagnostic test number of patients sensitivity for
    acute large blood loss (630 to 1150 ml)
    (95% CI)    		 specificity for
    acute large blood loss (630 to 1150 ml)
    (95% CI)    		 LR+ LR-
    postural pulse increment more than 30 beat/min or severe postural dizziness on standing from supine - 97%
    (91% to 100%)     		98%
    (97% to 99%)     		49 0.030
    postural pulse increment more than 30 beats/minute or severe postural hypotension on sitting from supine - 78%
    (% to %)     		98%
    (97% to 99%)     		39 0.22
    supine tachycardia (pulse > 100 beats/min) - 12%
    (5% to 24%)     		96%
    (88% to 99%)     		3.0 0.92
    supine hypotension (systolic blood pressure < 95 mmHg) - 33%
    (21% to 47%)     		97%
    (90% to 100%)     		11 0.69
    total

    • 25 studies were found that reported postural changes in vital signs in normovolaemic adults. The mean changes noted were
      • pulse increase: 10 beats/min (95% CI: 9 to 13)
      • fall in systolic blood pressure: 4 mmHg (95% CI: 2 to 6)
      • rise in diastolic blood pressure: 5 mmHg (95% CI: 3 to 8)
      These changes stabilised after 45 to 60 seconds standing upright.
    • Neither mild or moderate postural dizziness nor use of cardiovascular or psychotropic medication was associated with postural hypotension.
    • Postural changes were noted to last 12 to 72 hours following haemorrhage.
    • Capillary refill time was not found usefully to diagnose or exclude acute blood loss.

    Comments

    1. By limiting the search strategy to only Medline and English language articles, potentially useful material may have been missed.
    2. In cases where blood loss is suspected, signs which rule out bleeding are clinically more important than those which diagnose bleeding
    3. Note the fall in sensitivity of postural vital sign changes when patients were only sat up compared with when they were stood from being supine.
    4. A problem with applicability is that the studied population has been healthy volunteers; the presence of comorbidity may greatly reduce the usefulness of the test, since it would mainly reduce specificity.

    Citation

    1. McGee S, Abernethy WB, Simel DL: is this patient hypovolemic?. Journal of the American Medical Association 1999; 281 (11): 1022-1029
    Search Terms: hand-search
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer: Luis Ruiz Del Fresno

    Clinical Question.
    Patient suspected hypovolaemia or acute blood loss
    Intervention or Exposure clinical findings; capillary refill, mucous membranes, postural hypotension, pulse
    Outcome hypovolaemia or acute blood loss