title: Beta1- or beta2-blockers to improve hemodynamics following endotracheal adrenaline administration.
abstract: BACKGROUND
  The recommended dose for endotracheal adrenaline (0.02 mg/kg) causes a pronounced initial decrease in diastolic blood pressure which is detrimental at the initial phase of cardiopulmonary resuscitation. This effect was previously attributed to an early and preferential stimulation of the beta-adrenergic receptors causing vasodilatation unopposed by an alpha-adrenergic vasoconstriction. We hypothesized that inhibition of the beta2-adrenoreceptors is responsible for prevention of the deleterious initial decrease in blood pressure that takes place following endotracheal administration of adrenaline.
  
  
  METHODS
  Adrenaline (0.02 mg/kg) diluted with normal saline (5 ml) was injected into the endobronchial tree of anesthetized dogs 3 min following pretreatment with the non-selective beta-blocker propranolol, selective beta1-blocker metoprolol (0.1 mg/kg, i.v.), or without pre-treatment. Heart rate, blood pressure and arterial blood gases were monitored.
  
  
  RESULTS
  The selective beta-blocker metoprolol was almost as effective as the non-selective beta-blocker propranolol in attenuating the initial decrease in blood pressure following endotracheally administered adrenaline, a phenomenon that was previously attributed to inhibition of beta-adrenoreceptors.
  
  
  CONCLUSIONS
  The outcome of this study might be explained by a dose-related loss of cardioselectivity of metoprolol. Further studies are warranted to refine the pharmacological means to abort the initial blood pressure-lowering effect of endotracheally administered adrenaline.
authors.affiliation: Department of Anesthesiology and Critical Care, Tel Aviv Sourasky Medical Center, Tel Hashomer, Israel.
authors.forename: Ron
authors.initials: R
authors.lastname: Ben-Abraham
authors.forename: David
authors.initials: D
authors.lastname: Stepensky
authors.forename: Yudith
authors.initials: Y
authors.lastname: Assoulin-Dayan
authors.forename: Ori
authors.initials: O
authors.lastname: Efrati
authors.forename: Danny
authors.initials: D
authors.lastname: Lotan
authors.forename: Yossi
authors.initials: Y
authors.lastname: Manisterski
authors.forename: Mati
authors.initials: M
authors.lastname: Berkovitch
authors.forename: Zohar
authors.initials: Z
authors.lastname: Barzilay
authors.forename: Gideon
authors.initials: G
authors.lastname: Paret
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D004837:Epinephrine / Q000008:administration & dosage*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007267:Injections; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D014132:Trachea
chemical_list: D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D008790:Metoprolol; D004837:Epinephrine