title: Hypocapnia delays subsequent bupivacaine cardiotoxicity in rats under sevoflurane anesthesia.
abstract: BACKGROUND
  Hypocapnia induced following the accidental intravenous infusion of a local anesthetic can mitigate anesthetic toxicity, but the effects of hypocapnia induced prior to local anesthetic infusion are unknown. In this study, we examined the effects of prior hypocapnia on bupivacaine-induced cardiotoxicity in rats.
  
  
  METHODS
  Eighteen Sprague-Dawley rats were randomly divided into two groups: one receiving sevoflurane with normal ventilation (Control Group) and the other receiving sevoflurane with hyperventilation to induce hypocapnia (Hypocapnia Group). After 30 min, both groups received continuous intravenous infusions of 0.25% bupivacaine at 2 mg · kg(-1) · min(-1). The time taken to reach 25% and 50% reductions in heart rate (HR; HR-25%, HR-50%) and mean arterial pressure (MAP; MAP-25%, MAP-50%) from the start of bupivacaine infusion were recorded. The difference between HR-25% and MAP-25% was calculated. The times of the first ventricular premature beat (VPB) and final systole were also recorded.
  
  
  RESULTS
  In the Hypocapnia Group, HR-50%, MAP-25%, and MAP-50% were prolonged compared with the Control Group (P < 0.001). Furthermore, the interval between HR-25% and MAP-25% and the times between the first VPB and final systole were prolonged in the Hypocapnia Group (P < 0.001).
  
  
  CONCLUSIONS
  In rats under sevoflurane anesthesia, prior hypocapnia delayed the onset of bupivacaine-induced cardiotoxicity. Prior hypocapnia should be avoided during continuous bupivacaine nerve block under general anesthesia, because it may delay the detection of cardiotoxicity.
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Shuchun
authors.initials: S
authors.lastname: Yu
authors.affiliation: Department of Emergency and Disaster Medicine, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Mochizuki
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Takasumi
authors.initials: T
authors.lastname: Katoh
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Makino
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kawashima
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Mimuro
authors.affiliation: Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 1-20-1, Handa-yama, Higashi-ku, Hamamatsu-City, 4313192 Japan.
authors.forename: Shigehito
authors.initials: S
authors.lastname: Sato
references.citation: Acta Anaesthesiol Scand. 1974;18(2):88-103
references.pmid: 4428936
references.citation: J Anesth. 2011 Oct;25(5):710-5
references.pmid: 21748372
references.citation: Circulation. 2011 Mar 1;123(8):904-15
references.pmid: 21357845
references.citation: Reg Anesth Pain Med. 2010 Mar-Apr;35(2):181-7
references.pmid: 20301824
references.citation: Br J Anaesth. 2010 Dec;105 Suppl 1:i108-16
references.pmid: 21148650
references.citation: Anaesthesia. 2010 Feb;65(2):192-5
references.pmid: 19849674
references.citation: Anesth Analg. 1989 Nov;69(5):563-9
references.pmid: 2679230
references.citation: Anesth Analg. 1997 Feb;84(2):398-404
references.pmid: 9024037
references.citation: N Engl J Med. 1963 Nov 7;269:991-6
references.pmid: 14059732
references.citation: Can J Anaesth. 2008 Dec;55(12):836-46
references.pmid: 19050087
references.citation: Anesth Analg. 1985 Nov;64(11):1089-96
references.pmid: 4051206
references.citation: Br J Anaesth. 2000 Jan;84(1):92-4
references.pmid: 10740554
references.citation: Anesth Analg. 1991 May;72(5):627-34
references.pmid: 2018220
references.citation: Middle East J Anaesthesiol. 2008 Oct;19(6):1397-400
references.pmid: 18942254
references.citation: Int J Obstet Anesth. 2004 Oct;13(4):227-33
references.pmid: 15477051