Endotracheal administration of lidocaine inhibits isoflurane-induced tachycardia.
OBJECTIVE
Rapid increase in inspired isoflurane concentration increases heart rate and arterial blood pressure. To investigate whether the responses to isoflurane were elicited from stimulation of lower airway and/or lungs, haemodynamic responses to isoflurane administered after tracheal intubation were measured with or without endotracheal or intravenous administration of lidocaine.


METHODS
Seventy-two ASA physical status 1 patients, aged 21-50 yr, were randomly allocated to one of four groups. After tracheal intubation, anaesthesia was maintained with oxygen 100% and isoflurane 1.0% with controlled ventilation. After stabilization for 15 min, the isoflurane concentration was rapidly increased to 3.0% in three groups. An endotracheal lidocaine group received pretreatment with endotracheal 0.4 ml lidocaine 8% spray, an intravenous lidocaine group received pretreatment of 32 mg lidocaine i.v., and an isoflurane 3% group received not pre- treatment. In a control group, inspired isoflurane concentration was maintained at 1.0%. Heart rate, systolic blood pressure and end-tidal isoflurane concentration were measured every minute for 10 min.


RESULTS
The rapid increase in isoflurane concentration increased heart rate (25 +/- 12% increase from baseline; P < 0.05) but the increase was reduced by endotracheal lidocaine (9 +/- 9%), but not by intravenous lidocaine (22 +/- 13%). The plasma concentration of lidocaine was lower in the endotracheal lidocaine group (0.4 +/- 0.3 microgram.ml-1) than in the i.v. lidocaine group (1.5 +/- 0.2 micrograms.ml-1).


CONCLUSIONS
The isoflurane-induced tachycardia is reduced by pre-treatment with endotracheal lidocaine.
Takakura
K
K
Department of Anesthesiology and Reanimatology, Fukui Medical University, Japan. takakura@fmsrsa.fukui-med.ac.jp
Sugiura
Y
Y
Takeuchi
K
K
Goto
Y
Y
D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects; D001980:Bronchi / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D007442:Intubation, Intratracheal; D007530:Isoflurane / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis; D008012:Lidocaine / Q000008:administration & dosage* / Q000097:blood; D008168:Lung / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial; D013610:Tachycardia / Q000139:chemically induced / Q000517:prevention & control*; D013990:Tidal Volume
D000336:Aerosols; D018685:Anesthetics, Inhalation; D000779:Anesthetics, Local; D008012:Lidocaine; D007530:Isoflurane