Effect of Addition of Fentanyl to Xylocaine Hydrochloride in Brachial Plexus Block by Supraclavicular Approach.

AIM: This study was designed to quantitatively compare the effects of 1.5% xylocaine with 1.5% xylocaine and fentanyl (1 μg/kg) mixture for supraclavicular brachial plexus block.
MATERIALS AND METHODS: Sixty patients between the age group of 20-60 and scheduled for upper limb surgery were divided into two groups (xylocaine group and xylocaine plus fentanyl group). After performing supraclavicular brachial plexus block, an assessment was made for onset of analgesia, duration and degree of analgesia, block intensity, and for any other side effects.
RESULTS: Mean duration of analgesia is Group I is 2.1 h and in Group II is 8.1 h; a four-fold increase in duration of analgesia.
CONCLUSION: Addition of fentanyl to xylocaine for supraclavicular brachial plexus block has no significant effect on onset or quality of analgesia, but duration of analgesia is significantly prolonged.

INTRODUCTION

One of the most common injuries particularly with growing industrialization as well as mechanization of agriculture is upper arm injury. The advantage of regional anesthetic block is that it can be given in a full stomach patient, can be prolonged to any extent without any systemic effects, its minimal influence on cardiovascular and respiratory status, and its inexpensiveness, without any fear of drug interactions.

Anesthetic techniques that give both intra- and post-operative pain relief has gained importance in recent years.

The effects of postoperative pain are largely psychological, causing distress and anxiety and can be associated with less serious autonomic disturbances such as sweating and nausea. Good postoperative pain can reduce the metabolic response to trauma and thus may prevent or postpone negative nitrogen balance. Another advantage is that the pain-free patient has better mobility with immediate benefits and reduced incidence of chest infections and deep vein thrombosis.

There is definite scope for improvement in this area. Introduction of newer narcotics, patient-controlled analgesia using sophisticated equipment, using opioids in the regional block, and spinal opiate analgesia are some steps in this direction.[123] Some authors reported that there are no beneficial effects due to the addition of opiates in regional blocks.[45]

Cooperation of the patient must be obtained, for without them success will be poor.

The purpose of this study is to compare the effectiveness of addition of fentanyl to local anesthetic 1.5% xylocaine hydrochloride and local anesthetic 1.5% xylocaine alone in supraclavicular brachial plexus block for onset, degree of analgesia, duration of analgesia sedative effects, hemodynamic stability, side effects, and complications.

MATERIALS AND METHODS

After approval from the Ethical Committee, the study was done over a 6-month period in sixty patients belonging to both sexes.

Inclusion criteria

American Society of Anesthesiologists (ASA) Class I and II patients posted for operations on hand, forearm, and elbow; age group of 20–60 years belonging to both sexes; weight more than 50 kg; and patients who were ready to give written consent.

Exclusion criteria

Patients with neurological disorders, anemia, hypertension, and any cardiac and respiratory disorders were excluded from the study.

All patients were within the normal hematological and urological parameters range. The patients were explained and reassured about the procedure. Informed consent was obtained. The patients were randomly divided into two groups.

Group I: Xylocaine 1.5% (30 ml)

Group II: Xylocaine 1.5% (30 ml) with fentanyl 1 µg/kg body weight adrenaline is added to both groups.

The brachial plexus block characteristics are clearly affected by local anesthetic, adjuvant selection, and their dosing. The block spread mainly depends on technical intervention rather than pharmacological adjustment and no single study evaluated their significance. There is also a controversy that whether increasing local anesthetic mass (mass = concentration × volume) resulted in a higher success rate.

In our study, volume of the anesthetic solution to be injected is standardized to 30 ml in all patients. Even though the mg/kg dose of xylocaine hydrochloride in certain patients of Groups I and II was high, symptoms and signs of toxicity have not been encountered. The drug levels attained at the site of block mainly depend on the technique used and success rate of the block.

An assessment was made for the onset of analgesia, duration of analgesia, degree of analgesia, sedative effects, hemodynamic stability, intensity of block, and any other side effects.

After proper position of patient and skin preparation supraclavicular brachial plexus block, as described by Macintosh and modified by ball was used.

As soon as the block was given, patients were kept comfortably with the arm by the side. Blood pressure, pulse rate, and respiratory rate were noted every 5 min. Signs of drug toxicity were observed. Thiopentone sodium, succinylcholine hydrochloride, oxygen, and necessary equipment were kept ready for supplementation with general anesthesia and emergency intubation if needed.

The study by Bromage (1972), four-point scale for analgesia and drowsiness by BIONL and K. S. Shah (1975) was taken as guidelines for evaluation in the present study.

Onset of analgesia was taken as the period from the time of injection of analgesic solution to the absence of pinprick sensation as experienced by the patient.

Degree of analgesia is assessed by pinching the skin and quantified by a four-point scale by BiONL:

0: Normal sedation

1: Mild analgesia

2: Moderate analgesia

3: Surgical analgesia.

Duration of analgesia was taken as the period from the time of loss of pinprick sensation to the first appearance of pain as experienced by the patient.

Intensity of block – those blocks in which there is analgesia, motor weakness, subjective feeling of increased weight, warmth of the limb, and loss of position sense are classified as satisfactory.

Possible side effects were sought both during and after surgery. During surgery, we recorded all incidences of drowsiness, nausea, vomiting, pruritus, respiratory depression, and other adverse drug effects.

OBSERVATION AND RESULTS

The results and analyses of the study presented below were analyzed using analysis of variance, Student's t–test, and Chi-square test.

The two groups were comparable with regard to mean age, sex, and weight of the patients, all belonging to ASA Class I and II [Table 1].

Table 1

Patient characteristics (mean values)

Mean age was 38.16 in Group I and 42.6 in Group – II. The mean height and weight was 60.8 and 162.2 in Group I and 65.8 and 160 in Group II.

Sensory blockade was evaluated using pinprick technique.

The maximum time taken for onset of sensory blockade in Group I is 25 min and minimum time is 10 min, mean time is 14.8 min. The maximum time taken for onset of analgesia in Group II is 20 min, minimum time is 10 min, mean time is 15.54 min (P > 0.05) [Table 2].

Table 2

Onset of sensory blockade

Minimum time of duration of sensory blockade in Group A is 1.5 h, in Group B is 2 h. Maximum duration of analgesia in Group A is 2–5 h, in Group B is 13 h. The mean duration of analgesia in Group A is 2.1 h, Group B is 8.1 h. There is a significant prolongation of duration of analgesia is Group B. There is four-fold increase in duration of analgesia in Group B [Table 3].

Table 3

Duration of sensory blockade in both the groups

The success rate in the present study was 96.66%. Intensity of blockage in both the groups is shown in Table 4.

Table 4

Intensity of the block

Mean changes in heart rate, respiratory frequency, and oxygen saturation from preblock parameters are shown in Table 5, and the changes are found to be insignificant in both groups [Table 5].

Table 5

Cardiorespiratory changes

Supplementation was given to five cases in xylocaine group and six cases in xylocaine plus fentanyl group [Table 6].

Table 6

Supplementation

Table 7 shows the incidence of side effects in both groups, incidence of nausea was 13.33% in Group II and nil in Group I. Incidence of vomiting 6.66% in Group II and nil in Group I. Incidence of pruritus is 3.33% in Group II and nil in Group I.

Table 7

Incidence of side effects during and after surgery

In a different set of experiments, the pH of local anesthetic solutions was measured. At room temperature, the pH was 6.2 ± 0.1 (n = 4). It was decreased to 5.2 ± 0.1 (n = 4) by adding 100 µg of fentanyl.

DISCUSSION

The purpose of this study is to evaluate brachial plexus block by supraclavicular approach for various surgeries on upper extremity.

This study demonstrated that the addition of fentanyl to 1.5% xylocaine prolonged the duration of sensory blockade leading to a remarkable increase in postoperative analgesia.

There is an antinociceptive effect at the central and/or spinal cord level by the opiates.[6]

The presence of peripheral opioid receptors in animals has been reported,[789] but whether functional opioid receptors exist in human peripheral tissue is still unclear.

Several studies are done to determine whether adding the effects of opioids to local anesthetics would improve the peripheral nerve block efficacy.

Perineural injections of opioids were also done to observe their local anesthetic actions.[10]

Mays et al. study reported that morphine when injected perineurally provided longer-lasting pain relief than when injected intramuscularly. In another study done by Racz et al., it has been observed that morphine when added to lignocaine for axillary block, there is no change in onset time nor duration of block. Fletcher et al. study proved that addition of fentanyl to lignocaine with 1:200,000 epinephrine for brachial plexus block has a benefit of only faster onset of action but no change in success rate, onset time, or duration of analgesia by axillary approach.

These varied results in those studies may be due to the difference in anesthetic technique and opioid drug selection.

Adjuvants such as clonidine, vasoconstrictor drugs, steroids, opioids (morphine, fentanyl, and tramadol) are used in peripheral nerve blocks for improvement of quality and duration of block.[11]

Some studies have proved that fentanyl also has local anesthetic-like action.[12]

In our study, fentanyl when used with xylocaine prolonged the duration of sensory and motor blockade probably by direct action on dorsal nerve roots[1314] through opioid binding sites or by diffusion into surrounding tissues.

Studies of Kanaya et al. reported that faster onset of analgesia could result if lignocaine solution is alkalinized. In our study also there is a decrease in pH of xylocaine solution by adding fentanyl.

There may be some central opioid receptor-mediated actions due to systemic absorption of fentanyl.

Studies of Viel et al. showed that addition of opioids to brachial plexus block prolongs the analgesic duration that was similar to our study results.

Prolonged durations of analgesia may also be due to alteration in the pH of anesthetic solution by the addition of fentanyl.[1415]

CONCLUSION

The addition of fentanyl to xylocaine for supraclavicular brachial plexus block has no significant effect on the onset of analgesia, but the duration of analgesia is significantly prolonged.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.