INCIDENCE AND CLINICAL IMPORTANCE OF PERIOPERATIVE HISTAMINE-RELEASE - RANDOMIZED STUDY OF VOLUME LOADING AND ANTIHISTAMINES AFTER INDUCTION OF ANESTHESIA

Although histamine release is recognised as a common event during anae sthesia and surgery, few clinicians judge the resultant cardiorespirat ory disturbances serious enough to warrant prophylaxis with antihistam ines. We have assessed the incidence and importance of histamine relea se in a randomised 2 x 2 factorial study. 240 patients representing a routine throughput of major general surgery were studied during a stan dardised induction of anaesthesia and preoperative loading of the circ ulation with either Ringer solution or Haemaccel-35, with or without a ntihistamine prophylaxis with dimetindene (H-1) plus cimetidine (H-2). Cardiorespiratory disturbances were graded as detectable, clinically relevant, or life-threatening from observers' records of the anaesthes ia and the actions taken by the anaesthetists. Disturbances that were accompanied by significant rises in plasma histamine were further desi gnated histamine-related, and those that were not were designated hist amine-unrelated. Anaesthetists, observers, and designators were blinde d to whether or not the patients had received antihistamines and to wh ich solution was used for circulatory volume loading. Clinically relev ant or life-threatening histamine-related disturbances occurred in 8% of the patients who after induction of anaesthesia received Ringer wit hout antihistamines, in 26% of those who received Haemaccel without an tihistamines, and in 2% or less of those who received antihistamines ( p less-than-or-equal-to .0001). There were 4 life-threatening histamin e-related disturbances, all in patients who received Haemaccel without antihistamines (p<0.01). Histamine-unrelated disturbances occurred in 16% overall, with no obvious effect of Haemaccel or antihistamines.Th e histamine-related disturbances under anaesthesia were remarkable for their severity (even with small rises in histamine concentrations), f or the prevalence of bradycardia, and for the absence of skin signs. T heir likelihood and severity were increased in patients with tumours. The results of the trial make a case for routine prophylaxis with anti histamines as part of anaesthetic management.