Hypotension and Paradoxical Bradycardia

Relative or paradoxical bradycardia in the face of severe blood loss and hypotension fits squarely in the “it-just-ain’t-right” category. It isn’t right because it happens far more frequently than we recognize, and it contradicts what we have been taught about the body’s response to hemorrhage. A definite and significant subset of hypotensive patients will not mount a tachycardia response to hypotension, and a third or more of hypotensive trauma patients will present with bradycardia. (J Trauma 1998;45[3]:534 and 2009;67[5]:1051; J Am Coll Surg 2003;196[5]:679.) But it just isn’t relative bradycardia in the face of hypotension and hemorrhage where the heart rate’s reliability as a marker for severe blood loss fails. The truth is that even though there is an association between hemorrhage and tachycardia, it is actually unreliable and nothing like the four classes of hypovolemic shock described in that well-known table published by the Advanced Trauma Life Support course. The evidence shows that the ATLS table is more wishful thinking than reality. (Resuscitation 2011;82[5]:556; 2010;81[9]:1142; 2013;84[3]:309.) We still need to respect tachycardia in the face of hypotension, but heart rate is not a reliable indicator in the trauma patient. (J Am Coll Surg 2003;196[5]:679; J Trauma 2007;62[4]:812.) The sensitivity and specificity of tachycardia is poor. Patients with rapid heart rates frequently do not have serious blood loss, and others who are not tachycard...
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