Beta blocker infusion decreases the magnitude of core hypothermia after anesthesia induction.
BACKGROUND
Beta-1-receptor blockade reduces heart rate, cardiac output, and arterial pressure while increasing peripheral vascular resistance. It is possible that beta blockers not only inhibit the core-to-peripheral re-distribution of body heat and cutaneous heat loss due to vasodilation after anesthesia induction but also reduce the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output. The authors investigated whether the co-administration of esmolol or landiolol, ultra-short-acting beta blockers, attenuates the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation.


METHODS
Immediately prior to the induction of anesthesia, patients were randomly assigned to receive 0.2 mg kg-1 of landiolol (landiolol group; N=30), 1 mg kg-1 of esmolol (esmolol group; N=30), or 0.1 mL kg-1 of saline (control group; N=30). Heart rate, blood pressure, cardiac output, and tympanic, forearm, and digit temperatures were recorded. Forearm minus fingertip skin-surface temperature gradients (temperature gradient) were calculated.


RESULTS
Tympanic membrane temperatures 15 to 60 min after the induction of anesthesia were significantly higher in the esmolol group than in the control group although the temperature gradient was similar among the three groups. Both esmolol and landiolol inhibited the increase in HR and MAP after the induction of anesthesia and tracheal intubation. The cardiac index in the esmolol group was significantly lower than in the control group. The degree of hemodynamic attenuation after induction by esmolol was larger than that of landiolol.


CONCLUSIONS
The co-administration of esmolol, but not landiolol, attenuated the magnitude of initial re-distribution hypothermia after anesthesia induction and tracheal intubation. Esmolol likely prevented initial hypothermia because it attenuated the convective transfer of heat from the core to peripheral tissues by decreasing cardiac output.
Inoue
S
S
Department of Anesthesiology, Nara Medical University, Nara, Japan. seninoue@nmu-gw.naramed-u.ac.jp
Abe
R
R
Kawaguchi
M
M
Kobayashi
H
H
Furuya
H
H
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation / Q000009:adverse effects*; D001831:Body Temperature / Q000187:drug effects; D004396:Coloring Agents; D005260:Female; D013509:Gynecologic Surgical Procedures; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007035:Hypothermia / Q000139:chemically induced* / Q000517:prevention & control*; D007208:Indocyanine Green; D007442:Intubation, Intratracheal; D008875:Middle Aged; D009025:Morpholines / Q000008:administration & dosage / Q000627:therapeutic use; D011412:Propanolamines / Q000008:administration & dosage / Q000627:therapeutic use; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use
D000319:Adrenergic beta-Antagonists; D004396:Coloring Agents; D009025:Morpholines; D011412:Propanolamines; C077049:landiolol; D014508:Urea; D007208:Indocyanine Green; C036604:esmolol