Negishi et al. Anehst 2001; 94:218-222

Reviewed by: R. Prasad, MD

Summary:

• Previous studies suggesting higher incidence of fever in epidural vs. control groups actually did not use adequate "control" - controls receiving fentanyl analgesia may instead have had a lower incidence (vs. if no meds given) of fever, due to opioid suppression of febrile response.
• Fever during epidural analgesia should not be assumed to be a benign complication caused by the technique per se. Fevers should be taken seriously, and worked up as clinically appropriate.
• The threshold temp for investigating fever in patients receiving opioid analgesia (vs. epidural) should probably be lowered by about 0.5 deg Centigrade.

Comments:

• Very interesting study. Hope can be repeated on larger scale.
• Fairly small diff in peak temp found, but depending on trigger for infxn w/u (we used to use 38.5), this certainly could be a clinically significant difference. Don't know what the OB dept here uses.
• The integrated core temp seems useful, but I don't think it is clinically used ... maybe it should be?
• Wish list:
• more patients
• females ... do these findings apply to pregnant women?
• an epidural ropiv + IV fent group, for the sake of completeness

Methods:

• 8 male volunteers 4 days in random order.

• Given 50 IU/g human recombinant IL-2
• Measurements:
• tympanic and skin temp
• pupillary responses to evaluate fent effect
• venous fent levels
• venous IL-6, IL-8, TNF alpha, IL-10 levels
• vitals
• Studied integrated core temp (area under temp curve plotted vs time), peak temp, time-to-peak

Results:

• Incidence of fever same in control and epidural groups
• Fentanyl group had less fever, by several measures:
• integrated core temperature (centigrade-hours): 3.8 +/- 3.0 vs. 7.0 +/- 3.2
• max core temp (38.1 vs. 38.7)
• mean skin temp (33.8 vs. 34.7-35.3)
• percent of measures, during 3-8 elapsed hours, with core temp >38 deg (28 vs. ~70) and >38.5 det (6 vs. ~38)