title: Influence of thoracic epidural anesthesia on gastric oxygenation during hypothermia and hemorrhage.
abstract: OBJECTIVE
  Hypothermia preserves gastric mucosal microvascular oxygenation (μHbO2) during hemorrhagic shock. Additionally, hypothermia activates the sympathetic nervous system that leads to the release of vasopressin. The aim of this study was to evaluate whether the effect of hypothermia is mediated via the sympathetic nervous system and/or via vasopressin.
  
  
  METHODS
  In prospective and randomized experiments on five anesthetized dogs (foxhounds, cross-over design, 6 groups with n=5 per group) we analyzed the effects of hemorrhage on μHbO2 during mild hypothermia (HT, 34 °C), during additional thoracic epidural anesthesia (HT/TEA) and during additional vasopressin V1 receptor blockade (HT/VB). As control groups, effects of hemorrhage were studied under normothermia alone (NT), during additional thoracic epidural anesthesia (NT/TEA) and during additional vasopressin V1 receptor blockade (NT/VB).
  
  
  RESULTS
  Hemorrhage decreased μHbO2 from 81 ± 3 to 49 ± 8%. In contrast, in the presence of hypothermia, μHbO2 was significantly higher during hemorrhagic shock (from 79 ± 3 to 66 ± 9%) despite a similar decrease in DO2. The effect of hypothermia on μHbO2 was reduced in the presence of thoracic epidural anesthesia or vasopressin receptor blockade.
  
  
  CONCLUSIONS
  Hypothermia preserves μHbO2 during hemorrhagic shock. This effect is partially abolished during thoracic epidural anesthesia or during vasopressin receptor blockade. The sympathetic nervous system and the vasopressin V1 receptor are partially involved in mediating the effect of hypothermia on gastric oxygenation during hemorrhage.
authors.affiliation: Department of Anesthesiology, University Hospital Dusseldorf, Moorenstrasse 5, 40225 Dusseldorf, Germany. Electronic address: christian.vollmer@med.uni-duesseldorf.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmer
authors.affiliation: Department of Anesthesiology, University Hospital Dusseldorf, Moorenstrasse 5, 40225 Dusseldorf, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Nommensen
authors.affiliation: Department of Anesthesiology, University Hospital Dusseldorf, Moorenstrasse 5, 40225 Dusseldorf, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Watolla
authors.affiliation: Department of Anesthesiology, University Hospital Dusseldorf, Moorenstrasse 5, 40225 Dusseldorf, Germany.
authors.forename: Inge
authors.initials: I
authors.lastname: Bauer
authors.affiliation: Department of Anesthesiology, University Hospital Dusseldorf, Moorenstrasse 5, 40225 Dusseldorf, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Picker
mesh_terms: D000767:Anesthesia, Epidural; D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists / Q000494:pharmacology; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D004285:Dogs; D005260:Female; D005753:Gastric Mucosa / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D006470:Hemorrhage / Q000378:metabolism*; D007035:Hypothermia / Q000378:metabolism*; D008012:Lidocaine / Q000008:administration & dosage / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000502:physiology; D014667:Vasopressins / Q000502:physiology
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; C089517:vasopressin, 1-(2-mercapto-2,2-(cyclopentamethylene)propionic acid)-2-(O-methyl)Tyr-8-Arg-; D014667:Vasopressins; D001127:Arginine Vasopressin; D008012:Lidocaine; D010100:Oxygen
keywords: Hemorrhage; Hypothermia; Microcirculation; Sympathetic nervous system; Vasopressin receptor