The addition of sodium bicarbonate to prilocaine solution during i.v. regional anesthesia

Comparison of the effects of low volume prilocaine and alkalinized prilocaine for the regional intravenous anesthesia technique in hand and wrist surgery

Aim. Comparing the effectivity of prilocaine and prilocaine alkalinized with 8.4% NaHCO₃ in terms of sensory and motor block onset and termination durations in RIVA technique considering patients' satisfaction and tolerance with application of tourniquet undergoing hand-wrist surgery. Materials and Methods. 64 patients were randomised into two groups. First group (Group P) was administered prilocaine and second group (Group PN) was administered prilocaine + %8.4 NaHCO₃. Sensory and motor block onset and termination times and onset of tourniquet pain were recorded. Results. No significant difference was found between the two groups in terms of onset and termination of sensory block and the onset of motor block. The duration of the motor block was longer in Group PN than in Group P (P < 0.05). Tourniquet pain was more intense in Group P (P = 0.036). In Group PN, the use of additional drugs was recorded at a lower rate and patients' satisfaction was higher than Group P. Conclusion. In the present study, it was established that alkalinization of prilocaine had no effect on the duration of sensory block and it prolonged the duration of motor block, increased patients' satisfaction, and decreased tourniquet pain. It is our suggestion that future studies should be carried out on the issue by using different volumes.

Comparison of the effects and disposition kinetics of lidocaine and (+/-)prilocaine in patients undergoing axillary brachial plexus block during day case surgery

OBJECTIVE

The aim of this investigation was to compare the clinical effects and pharmacokinetics of lidocaine and prilocaine in two groups of 15 patients undergoing axillary brachial plexus anaesthesia.

METHODS

The study had a randomised design. Patients were allocated to one of the two groups of 15. Each group received either lidocaine (600mg = 2.56 mmol/L + 5 mg/L adrenaline) or prilocaine (600mg = 2.72 mmol/L + 5 mg/L adrenaline), injected over a period of 30 seconds. Onset of the surgical analgesia was defined as the period from the end of the injection of the local anaesthetic to the loss of pinprick sensation in the distribution of all three nerves.

RESULTS

The mean onset time of surgical analgesia of both lidocaine and prilocaine was 10 minutes. Lidocaine was biexponentially eliminated with a rapid elimination phase half-life (t((1/2)alpha)) of 9.95 +/- 14.3 minutes and a terminal elimination phase half-life (t((1/2)beta)) of 2.86 +/- 1.55 hours. Lidocaine was metabolised to MEGX (monoethylglycylxylidide); time to reach maximum plasma concentration (tmax) 2.3 +/- 0.8 hours; maximum plasma concentration (C(max)) 0.32 +/- 0.13 mg/L; t((1/2)beta) 2.4 +/- 2.4 hours. Lidocaine total body clearance was 67.8 +/- 28.8 L/h. Prilocaine was rapidly and biexponentially eliminated with a t((1/2)alpha) of 9.4 +/- 18.4 minutes and a t((1/2)beta) of 2.12 +/- 1.28 hours. The total body clearance of prilocaine (150 +/- 53 L/h) was higher than that of lidocaine (p = 0.0255). Both compounds demonstrated a comparable volume of distribution (Vd), while the volume of distribution at steady-state (V(ss)) and the volume of distribution in the second compartment (V(beta)) values of prilocaine were a factor of 1.6 higher than those of lidocaine (p < 0.001). Both compounds showed a comparable t((1/2)alpha) (p > 0.8) and a comparable t((1/2)beta) (p = 0.26).

CONCLUSION

Following axillary administration, lidocaine and prilocaine demonstrated similar pharmacokinetic behaviour and could therefore be used as the clinical preference for this regional anaesthesia technique.

Comparison of the disposition kinetics of lidocaine and (+/-)prilocaine in 20 patients undergoing intravenous regional anaesthesia during day case surgery

OBJECTIVE

The aim of this investigation was to compare the pharmacokinetics of lidocaine and prilocaine in two groups of 10 patients undergoing intravenous regional anaesthesia.

METHOD

The study had a randomized design. The patients were allocated to one of the two groups of 10. Each group received either lidocaine (200 mg = 0.855 mM) or prilocaine (Citanest, 200 mg = 0.909 mM), injected intravenously over a period of 30 s. Onset of the surgical analgesia was defined as the period from the end of the injection of the local anaesthetic to the loss of pinprick sensation in the distribution of all three nerves.

RESULTS

The mean onset time of surgical analgesia of lidocaine was 11.2 +/- 5.1 min and that of prilocaine was 10.9 +/- 6.0 min. After releasing the tourniquet, lidocaine is bi-exponentially eliminated with a t1/2 alpha of 4.3 +/- 2.1 min and a t1/2 beta of 79.1 +/- 31.2 min. Total body clearance was 0.86 +/- 0.39 litres/min. Prilocaine is rapidly and bi-exponentially eliminated with a t1/2 alpha of 3.0 +/- 1.6 min and a t1/2 beta of 29.9 +/- 15.7 min. The total body clearance of prilocaine is higher than that of lidocaine, 4.15 +/- 1.31 vs. 0.86 +/- 0.39 litres/min, respectively (P = 0.0007). Both compounds show comparable volumes of distribution (Vd, Vss and V beta) and a comparable t1/2 alpha (4.3 +/- 2.1 vs. 3.0 +/- 1.6 min; P = 0.1780). The t1/2 beta for the two compounds were different (P = 0031); 79.1 +/- 31.2 min for lidocaine and 29.9 +/- 15.7 min for prilocaine. The mean residence time (MRT) of lidocaine (193 +/- 233 min) also differed significantly from that of prilocaine (33.4 +/- 19.9 min; P = 0.0022).

CONCLUSION

Lidocaine is preferred for relatively long procedures and prilocaine for short procedures.

The use of 0.25% lidocaine with fentanyl and pancuronium for intravenous regional anesthesia

The present study was designed to assess the efficacy of fentanyl and pancuronium combined with dilute lidocaine solution for intravenous regional anesthesia of the arm. Forty adult patients undergoing upper limb surgery were randomly allocated to receive either 0.6 mL/kg of 0.5% lidocaine (3 mg/kg) or 0.6 mL/kg of 0.25% lidocaine (1.5 mg/kg) with 1 microg/kg of fentanyl and 0.5 mg of pancuronium. The onset of sensory and motor blocks was significantly shorter in the 0.5% lidocaine group (P < 0.05). However, no differences in analgesia or motor blockade were found between the two groups at 20 min tourniquet time. Regional anesthesia was considered successful in more than 85% of patients. One patient in the 0.25% lidocaine group experienced a transient diplopia after tourniquet release. Postoperative analgesia time was similar in the two groups. We conclude that the addition of fentanyl plus pancuronium to the lidocaine solution reduces the dose of the local anesthetic and possibly systemic toxicity.

Intra-arterial regional anaesthesia for hand surgery with alkalinized 0.5% lignocaine

Intra-arterial regional anaesthesia (IARA) for hand surgery is an old, forgotten technique. One of the causes of low popularity may be a scalding sensation in the hand during intra-arterial injection of lignocaine, which may be caused by low pH of lignocaine's solution. In this randomized, double-blind study, normal (pH 5.2-5.3) or alkalinized (pH 7.2-7.3) preservative-free 0.5% lignocaine 1.5 mg kg-1 was injected into the radial arteries of forty adult patients to produce anaesthesia for ambulatory hand surgery. Scalding sensation in the hand during intra-arterial injection (VAS) was less pronounced with alkalinized lignocaine (P = 0.04). The time of onset and regression of analgesia was similar in both groups. Four patients in group 1 (normal lignocaine) and six patients in group 2 (alkalinized lignocaine) needed supplemental analgesia at the start of surgery (NS). Cannulation time, operating conditions, motor blockade, surgical-, and tourniquet pain scores (VAS) and patient's acceptance were similar. Three patients (two in group 1 and one in group 2) had minor systemic adverse effects after tourniquet release (NS). Nine patients in group 1 and seven in group 2 developed minor bruises after cannulation (NS). No other sequelae of intra-arterial injections were observed. We conclude that alkalinized 0.5% lignocaine was less painful on injection than normal lignocaine and should be preferred for intra-arterial anaesthesia for hand surgery.