Autonomic nervous system state: the effect of general anaesthesia and bilateral tonsillectomy after unilateral infiltration of lidocaine.
BACKGROUND
Autonomic nervous system (ANS) sensitively responds to intraoperative stress. Several indices characterizing the state and responses of autonomic signs to nociceptive stimuli have been introduced. This study evaluated the behaviour of ANS descriptors after induction, before and during tracheal intubation, and during bilateral tonsillectomies after random and blinded unilateral infiltration of lidocaine 1% until emergence from anaesthesia.


METHODS
Twelve patients undergoing bilateral tonsillectomy were anaesthetized with fentanyl and propofol (induction) and sevoflurane (maintenance). All patients were monitored throughout anaesthesia for middle finger temperature, non-invasive arterial pressure, heart rate (HR) and pulse rate (PR), state entropy (SE) and response entropy (RE), and surgical pleth index (SPI). New parameters complementing the above and characterizing the ANS state (ANSS) and responses are pulse-to-pulse interval (PPI), pulse plethysmographic amplitude (PPGA), ANSS, and an index based on maximal ANSS for the subject (ANSSI). Serial data were stored as 10 s averages into a laptop computer.


RESULTS
Anaesthesia induction was associated with an increase in finger temperature to >30 degrees C within 10 min, whereas PPGA increased to their maximum levels within 5 min. Laryngoscopy and intubation were associated with transient autonomic responses in most patients. All autonomic signs indicated statistically significant sympathetic activation during saline-infiltrated tonsillectomies when compared with lidocaine-infiltrated sides (P<0001). Hypnotic measures (SE and RE) and finger temperatures did not differ between the sides.


CONCLUSIONS
HR, PPI, PPGA, ANSS, ANSSI, SPI, and RE-SE detect autonomic responses to nociceptive stimuli and differentiate between tonsillectomies on locally anaesthetized tonsils from controls.
Paloheimo
M P J
MP
Department of Anaesthesiology and Intensive Care Medicine, Eye-ENT Hospital, Helsinki University Central Hospital, Haartmanstreet 4, PO Box 220, Fi-00029 HUS Helsinki, Finland. markku.paloheimo@gmail.com
Sahanne
S
S
Uutela
K H
KH
D000328:Adult; D000768:Anesthesia, General / Q000379:methods; D019162:Anesthetics, Combined / Q000494:pharmacology; D018681:Anesthetics, General / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D004311:Double-Blind Method; D019277:Entropy; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D007442:Intubation, Intratracheal / Q000379:methods; D007828:Laryngoscopy; D008012:Lidocaine / Q000494:pharmacology*; D016343:Monitoring, Intraoperative / Q000379:methods; D014068:Tonsillectomy; D055815:Young Adult
D019162:Anesthetics, Combined; D018681:Anesthetics, General; D000779:Anesthetics, Local; D008012:Lidocaine