A systematic review 1 including 10 phlebotomy studies (504 participants in the moderate blood loss group and 108 in the large blood loss group) and 4 clinical studies (179 participants) was abstracted in DARE. The most helpful physical findings are either severe postural dizziness (preventing measurement of upright vital signs) or a postural pulse increment of 30 beats/minute or more that gave a sensitivity for moderate blood loss of 22% (95% CI 6% to 48%) and a sensitivity for large (acute) blood loss of 97% (95% CI 91% to 100%). The corresponding specificity is 98% (95% CI 97% to 99%). Supine hypotension and tachycardia are frequently absent, even after up to 1150 mL of blood loss (sensitivity 33%, 95% CI 21% to 47% for supine hypotension). In patients with vomiting, diarrhea, or decreased oral intake, the presence of a dry axilla supports the diagnosis of hypovolaemia (positive likelihood ratio = 2.8, 95% CI 1.4 to 5.4) and moist mucous membranes and a tongue without furrows argue against it (negative likelihood ratio = 0.3, 95% CI 0.1 to 0.6). In adults the capillary refill time and skin turgor have no proven diagnostic value.
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