Preemptive Effects of a Combination of Preoperative Diclofenac, Butorphanol: DISCUSSION

In: Anesthesia

7 Feb 2010

Orthognathic surgery

This study was performed to investigate whether preemptive multimodal analgesia could be obtained in patients undergoing SSRO. However, the effects of preemptive multimodal analgesia were not confirmed in SSRO patients with the current protocol. There were no significant differences between the 2 groups either in POPI scores or in the total dosage of postoperative diclofenac medication sodium.

McQuay reviewed several reports on preemptive analgesia and evaluated their validity on the basis of pre-and postincisional comparison mentioned by Woolf. McQuay, however, accepted the study by Kavanagh et al, which compared preoperative multimodal analgesia with no preoperative analgesic treatments. The subjects in both groups in the Kavanagh study received morphine on demand postoperatively. The reason why this study was included in McQuay’s criteria was that it was the clearest example of a randomized controlled trial using multiple interventions to demonstrate a preemptive effect. The authors believe that this is also applicable to our study.
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The assessment of POPI in the PACU was conducted after confirmation of adequate arousal of the patient. However, as our preliminary study (unpublished data) revealed, there was difficulty in obtaining POPI scores on the VAS from patients at rest in the supine position. Therefore, assessment was done with the NRS. The preliminary study showed a definite correlation (r = .977) between the NRS and the VAS employed for parallel assessment of POPI (Spearman’s rank correlation); therefore, we believe the use of the NRS for assessing POPI in the PACU did not affect the results of the study.

Diclofenac sodium, an NSAID, is effective in inhibiting the synthesis of prostaglandin (PG). Its concentration producing a 50% inhibition is 1.6 jjiM/L, a value that is less than those of other NSAIDs, indicating a potent inhibitory effect on PG synthesis. In a study treating patients undergoing cholecystectomy with rectal sodium, 50 mg, an analgesic effect began to appear in 34 minutes and lasted until 5 hours after administration. The mean intervals from the administration of diclofenac sodium to incision and to the end of surgery indicate that was effective in inhibiting PG synthesis in the present study, with an effect that lasted throughout the procedure.

Odor et al blocked the inferior alveolar nerve with 2 mL of 2% lidocaine solution containing 1:80,000 (12.5 |xg/mL) epinephrine. The duration of full anesthesia, as assessed by the electric pulp test of molar teeth, was 88 ± 28 minutes (mean ± SD), and complete recovery occurred at a mean of 123 ± 32 minutes. The duration of full anesthesia, as assessed by the pin prick test of soft tissue, was 151 ± 28 minutes, and complete recovery occurred at a mean of 266 ± 44 minutes. Yoshino et al. blocked the inferior alveolar nerve with 2 mL of 1% lidocaine solution containing 1: 100.000       (10 |xg/mL) epinephrine. The duration of anesthesia was 166.2 ± 4.3 minutes. In the present study, surgery was started at least 5 minutes after the induction of regional anesthesia and bilateral inferior alveolar nerve blocks with 8 mL of 1% lidocaine solution containing 1:100,000 (10 |xg/mL) epinephrine and lasted for a mean of 137.3 ± 44.9 minutes in group P, so that lidocaine would be expected to have provided adequate nerve block during the operation. kamagra jelly uk

Butorphanol, a kappa receptor agonist, appears to exert analgesic effect on pain associated with oral surgery because kappa receptors are known to be present in the spinal trigeminal nucleus. The duration of action after intravenous administration is about 2-4 hours. In the present study, butorphanol was administered at a dose of 10 u,gAg. The mean interval between butorphanol administration and the end of surgery was 179.1       ± 47.0 minutes (mean ± SD). It appears that the potency and duration of the analgesic effect of butorphanol were adequate during the surgery.

Kissin pointed out 3 causes for lack of obvious preemptive analgesia: (1) incomplete effect in the preemptive group: insufficient duration of antinociceptive protection during surgery and during the initial postoperative period (inflammatory phase) and insufficient degree of preventive blockade; (2) partial preemptive effect in the control group: the use of opioids in the control group in induction of anesthesia and during surgery, and (3) surgery with low-intensity noxious stimuli. The mean values of ETISO, SBP, HR and RPP were significantly lower in group P than in group C. Thus, it seems that adequate antinociceptive effects were obtained in group P patients during surgery. Since the patients in group С did not receive any analgesic before and during surgery, the possibility of a partial preemptive effect can be rejected. In addition, the fact that the mean value of ETISO was greater in group С than in group P indicates the high-intensity noxious stimulation of SSRO. However, the degree of antinociceptive protection during the initial postoperative period might be insufficient because  sodium as a postoperative analgesic was only received by patient request. The method of postoperative analgesic administration in the present study possibly caused insufficient duration of antinociceptive protection and insufficient inhibition of the inflammatory pain during the initial postoperative period.

It has been reported that NMDA receptors are involved in central sensitization and that NMDA receptor antagonists blocked the wind-up phenomenon. Clinical studies are underway to reduce postoperative pain through prevention of central sensitization. Further studies are needed to investigate the feasibility of inducing preemptive analgesia by administration of NMDA receptor antagonists to patients undergoing SSRO.

In conclusion, preemptive multimodal analgesia was not observed in this study.

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