The use of a local anesthetic foot block in patients undergoing outpatient bony forefoot surgery: A prospective randomized controlled trial☆

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• Abstract
• Materials and methods
• Results
• Discussion
• References
• Copyright

Abstract 

Foot blocks are known to prolong postoperative pain relief. Consequently, their use has been extended to patients having outpatient surgery, despite little evidence to show improved patient satisfaction. Indeed, patients having outpatient surgery actually may be less satisfied because they will first experience pain at home on the first postoperative night, which may be more severe than anticipated. In this prospective, randomized, blinded study, 42 patients having unilateral outpatient bony forefoot surgery were assigned randomly to either having the surgery under general anesthesia alone or under general anesthesia with supplementary foot block (0.5% bupivicaine). All patients were assessed at home by telephone interview on the first and second postoperative day. There was a significantly longer time to first perceived pain in the foot block group compared with the control group, but no difference in the number of postoperative analgesic tablets consumed, no difference in pain score on the first night, first postoperative or second postoperative day, or any difference in the overall patient satisfaction scores at 2 days. The authors conclude that a local foot block, although prolonging the time to first perceived pain, does not improve patient satisfaction and is not detrimental when used as analgesia in the outpatient setting. (The Journal of Foot & Ankle Surgery 42(1):24–29, 2003)

Keywords:  outpatient, foot surgery, general anesthesia, foot block, local anesthesia

Previous studies have shown peripheral nerve blocks to be highly effective for patients having in-patient surgery, both in delaying the onset of pain and reducing pain in the early postoperative period ¹, ², ³, ⁴. The effects of most peripheral nerve blocks last between 6 to 12 hours ¹, ², ³, ⁵. Marshall and Serpell, however, have shown that for in-patients having foot surgery, 50% experience severe pain and require parenteral opioids once the peripheral nerve block wears off ⁽⁶⁾.

Because of the prolonged analgesic effect, their use has been extended to patients having outpatient surgery. In particular, the use in bony forefoot surgery may be based primarily on the assumption that by reducing pain in the early postoperative period, patient satisfaction would improve. However, most of those patients having a postoperative foot block likely will have been discharged home by the time the block wears off. Consequently, patients will first experience pain when at home, and this may be much more severe than anticipated. Paradoxically this may lead to poor postoperative pain control and thus poor patient satisfaction.

To the authors' knowledge, there has been no published data on whether local foot blocks improve or alter patient satisfaction after bony forefoot surgery performed on an outpatient basis. In this prospective, randomized, controlled trial, we investigated whether foot blocks improve patient satisfaction in those patients having outpatient bony forefoot surgery.

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Materials and methods 

Patients undergoing unilateral out-patient bony forefoot surgery (ASA 1 or 2) in our institution were recruited into the prospective randomized trial. The surgical procedures that were performed are listed in Table 1. Patients merely undergoing soft-tissue forefoot procedures were excluded, as were patients who were not able to be contacted by telephone postoperatively. All patients were consented fully before inclusion in the study and the study was approved by the local ethical committee.

Table 1. Surgical and demographic data mean values

MT, metatarsal; MTP, metatarsophalyngeal.

Patients were allocated randomly (via sealed envelope) into 2 groups: general anesthetic plus foot block (FB) and general anesthetic alone (control). No premedication was given. All patients received a standard general anesthetic consisting of 2,6,-diisopropylphenol induction, fentanyl, and spontaneous respiration of isoflurane in a nitrous oxide/oxygen mixture via a laryngeal mask airway. Further intraoperative morphine and/or nonsteroidal anti-inflammatory (NSAID) was given according to the routine practice and discretion of the anesthetist, who was not blind to the patient group.

Twenty milliliters of 0.5% plain bupivicaine was used as the FB and administered via a 25-g needle to 3 nerves at the level of the ankle (superficial peroneal, deep peroneal, and posterior tibial) as described by Eriksson ⁽⁷⁾. The foot block was given after induction so the patient was blinded to their experimental group. The block was performed by either the surgeon or anesthetist. No placebo block was given to patients in the control group, and thus the anesthetist could not be blind to the patients' allocated group.

When appropriately recovered, patients were discharged with oral analgesia (combined codeine phosphate 30 mg and acetaminophen 500 mg per tablet) to take as required (maximum 8 tablets/d). We recorded the duration of anesthetic, time of day of anesthetic, and the use of intraoperative analgesic supplements.

All patients were followed up with a telephone questionnaire on the first and second postoperative day by 1 of the authors who had not been present in the operating room (thus blind to the patient's allocated group). The time of telephone questionnaire was standardized such that patients having the procedure in the morning were contacted in the morning the next day, whereas those having surgery in the afternoon were contacted in the afternoon on each study day. Thus, on the first and second postoperative days, patients were questioned approximately 24 hours and 48 hours postoperative, respectively.

At each telephone encounter, the following data were recorded (when applicable) (Fig. 1): time when the patient could first recollect pain postoperatively (having noted previously the time of anesthetic we then determined the length of the postoperative pain-free period), subjective score of the pain on the previous night and at the time of the interview using a verbal incremental pain score (1 = no pain; 10 = severe pain), patients' overall analgesic consumption by noting the number of tablets they had consumed (the patients had been instructed on entering the study to document the exact number of tablets they had consumed), sleep disturbance (0 = none, 1 = <2 hours, 2 = <4 hours, 3 = >4 hours), loss of appetite (0 = no appetite, 1 = does not feel like food but had eaten small amount, 2 = some loss of appetite but eating, 3 = full appetite), overall activity level (0 = still in bed, 1 = up but a “pottering in a dressing gown,” 2 = dressed but not at full activity, 3 = return to full activity), and the presence of any surgical or anesthetic complications (e.g., postoperative nausea and vomiting).

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• Fig. 1. 

  Patient questionnaire.

On the second interview, we also asked for a rating of overall satisfaction via using a simple verbal score (1 = would definitely have the surgery performed the same way using the same type of pain relief, 2 = probably, 3 = unsure, 4 = would not have the surgery performed again using that package of pain relief). Finally, we inquired whether any patient had consulted their general practitioner or emergency department during the follow-up period. This allowed us to assess any severe inadequacy in postoperative pain control. The results were analyzed using the Mann Whitney U test or Fisher exact test for the nonparametric data. The level of statistical significance was set at P < .05.

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Results 

Forty-two patients were recruited into the study. One FB patient and 1 control patient needed overnight admission owing to poor pain control and were excluded from subsequent analysis. One additional patient (FB group) was excluded because of poor control of epilepsy, needing overnight admission. The remaining 39 patients (18 FB, 21 control) comprised the entire study population. The results were analyzed using a computer statistics program (Sigma Stat; Jandel Scientific, San Rafael, CA) and are presented in Tables 1 and 2 and Figure 2.

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• Fig. 2. 

  Bar chart showing time to first perception of pain for each patient in the 2 groups.

Table 2. Patient response data

There was no significant difference in the men:women ratio, in the mean age of the patients, or duration of anesthetic between the 2 groups (Table 1). The patients in the control group received more intraoperative analgesic supplements (NSAID and/or morphine). This difference was significant for morphine (P = .035; Fisher exact test), but not significant for NSAIDs (P = .052; Fisher exact test).

The mean time to the patients first perception of pain was significantly longer in those patients having an additional FB (mean, 12.0 v 5.5 h; P = .002, Mann Whitney). However, there were no significant differences in the median pain scores for patients' pain perception on the first night, or on the first or on the second postoperative day (Fig. 2). There also was no significant difference in the patients' overall satisfaction score. No patient consulted their general practitioner or emergency department during the follow-up period.

Despite the control group receiving more intraoperative morphine, there was no significant difference in patient analgesic consumption (total number of tablets consumed), appetite scores, or the scores for patient activity level between the 2 groups (Table 2). One patient in the FB group was found to have suffered a peripheral nerve injury that might have been secondary to the administration of the FB or pressure from the plaster of Paris cast applied to the foot.

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Discussion 

We have shown that administration of a local anesthetic FB to patients having bony forefoot surgery under general anesthesia as an outpatient procedure can extend the time to first perception of pain significantly, but makes little difference with regard to pain relief on the first postoperative night or thereafter. Furthermore, we have shown that the additional use of FB does not improve patient satisfaction. Finally, we have shown that FB is not detrimental when used for analgesia in the outpatient setting. This counters the hypothesis that patients may be less satisfied if they would first experience pain at home, which may be more severe than anticipated.

We recognize there are several limitations of our study design. Although the patient and the telephone interviewer were blinded to the arm of the study each patient was entered, the anesthetist was not. As such, the anesthetic could be modified accordingly by giving additional opioids and/or NSAIDs to patients in the control group during surgery. Our results confirmed this bias (Table 1). McQuay et al. ⁽²⁾ have shown that additional opioid administration with premedication extends the mean duration of postoperative analgesia from 2 to 9 hours for patients having in-patient orthopedic surgery. In our study, we believe that the intraoperative opioid administration by the anesthetist to patients in the control group probably contributed to the extended time to the first perception of pain. This group of patients reported a mean of 5.5 hours until perception of pain, which was longer than we expected.

We did not blind the anesthetist in our study protocol because of the known small risk for complications associated with administration of a peripheral nerve block. We considered the administration of a saline placebo block to the control group an unacceptable risk. One of our FB patients may have sustained a nerve palsy from the block. Although we did not assess the effectiveness of the FB in hospital, data from the telephone questionnaire showed that the majority of the blocks were effective with a significantly extended time to first perceived pain compared with the control group, although a few blocks must have failed (Fig. 2).

We hypothesized that patients undergoing outpatient forefoot surgery with an adjuvant FB might paradoxically be less satisfied because they would first experience pain when at home on the first postoperative night, which may have been more severe than anticipated. This clearly did not occur in our patients. Although the FB group showed a significantly longer time to first recall of pain, it made no difference to the patients reported score of pain severity on the first postoperative night (median score, 4 v 5; p = 0.32, Mann Whitney). There was no difference in the postoperative analgesic consumption between the 2 groups (mean tablet consumption, 8.4 v 9.9; P = .12, Mann Whitney).

We also were surprised to find no significant difference in the median patient overall satisfaction scores between the 2 groups (P = .24). We had asked our patients to give a satisfaction score early in their postoperative period, on the second postoperative day, rather than during an outpatient clinic visit. This was to allow for a more accurate assessment of poor pain control in the immediate postoperative period and avoid the issues associated with retrospective recall. However, most patients in both groups gave a satisfaction score of 1 (would have the same pain control regimen again), and there was no correlation between time to first pain and overall satisfaction score. We could not tell if our patients were intimidated into giving a falsely optimistic score to the investigator conducting the telephone interview and would have responded with a different satisfaction score to a friend.

Although a larger study population would be required to be certain that no significant difference exists with regard to patient satisfaction between the 2 groups, using a power value of .8, this study would be able to detect a difference in a satisfaction score of 1. Alternatively, to detect the current difference in patient satisfaction with any significance would require 85 patients per sample group.

We specifically did not ask patients if they thought they had been given the block. Interestingly, no patient spontaneously asked during the telephone interviews either. Thus, we are confident that both the patient as well as the telephone interviewer were blinded with regard to the perioperative anesthesia received.

We found no difference in patients' perception of pain control on the first and second postoperative days. The latter findings concur with those of Needoff et al. ⁽³⁾, who reported in their prospective, randomized trial that addition of FB to general anesthesia only made a significant difference to pain scores during the first 6 hours and not beyond, although these were not patients having outpatient surgery.

In conclusion, we found a local anesthetic FB supplement to general anesthesia in patients having outpatient bony forefoot surgery gave improved early postoperative pain relief with no worsening of pain control on the first postoperative night. We conclude that FB is not detrimental to patients having outpatient surgery, although its use did not improve overall patient satisfaction.

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References 

1. Sharrock NE, Waller JF, Fierro LE. Midtarsal block for surgery of the forefoot. Br J Anaesth. 1986;58:37–40
   • View In Article
   • MEDLINE
2. McQuay HJ, Carroll D, Moore RA. Post-operative orthopaedic pain—the effect of opioid premedication and local anaesthetic blocks. Pain. 1988;33:291–295
   • View In Article
   • Abstract
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3. Needoff M, Radford P, Costigan P. Local anaesthesia for post-operative pain relief after foot surgery—a prospective randomised trial. Foot Ankle Int. 1995;16:11–13
   • View In Article
   • MEDLINE
4. Rongstad K, Mann RA, Priekson D, Nichelson S, Horton G. Popliteal sciatic nerve block for post-operative analgesia. Foot Ankle Int. 1996;17:378–382
   • View In Article
   • MEDLINE
5. Haldane G, Serpell MG. Midtarsal block for surgery on the forefoot; what is the optimal local anaesthetic mixture?. Br J Anaesth. 1997;78:468
   • View In Article
6. Marshall S, Serpell MG. Comparison of two methods of ankle block for foot surgery. Br. J Anaesth. 1995;74:481
   • View In Article
7. Eriksson E. Illustrated Handbook of Local Anaesthesia. In: London: Lloyd Luke,; 1979;p. 108–111
   • View In Article