Intravenous regional anaesthesia

Intravenous regional anaesthesia, or Bier's block, is a useful and safe technique for anaesthetizing distal limbs for short surgical procedures. It is most commonly used for reduction of forearm fractures within the emergency department and can be a useful method of providing anaesthesia in patients who may be unsuitable for a general anaesthetic, or when skills or equipment for other forms of regional anaesthesia are unavailable. When performed as recommended it has a proven safety record.     

A comparison of prilocaine and lidocaine for intravenous regional anaesthesia for forearm fracture reduction in children

BACKGROUND: In this prospective blinded randomized study, we compared prilocaine and lidocaine for intravenous regional anaesthesia for forearm fracture reduction in children. METHODS: Two hundred and seventy-nine children, aged 316 years, were enrolled and randomly assigned to receive 3 mg.kg-1 of either prilocaine or lidocaine. The severity of fracture was classified according to the displacement of the radius (i.e., no radial fracture, angulated, partly displaced or completely displaced). Pain during the procedure was assessed as none, minimal, moderate or severe. RESULTS: There was no significant difference between agents in the proportion of patients with a successful reduction (prilocaine 94%, lidocaine 92%). Compared with less severe fractures, successful reduction was less common in the completely displaced fractures (P < 0.001) but there was no significant difference in this category between anaesthetic agents (successful reduction: prilocaine, 84%; lidocaine, 78%). Analgesia was superior in the lidocaine group with more patients having no or minimal pain (prilocaine, 78%; lidocaine, 90%, P < 0.05). CONCLUSIONS: Both agents are effective for forearm fracture reduction in children with a high incidence of successful reductions, particularly in the minimally or nondisplaced fractures. Lidocaine provided superior analgesia.     

Intravenous regional anaesthesia for foot surgery

Intravenous regional anaesthesia, confined to the distal lower limb and using bupivacaine 0.25%, was studied in 12 patients undergoing orthopaedic procedures to the feet. The technique was well accepted by both surgeons and patients and was free from serious toxicity. Bupivacaine was demonstrated in the systemic venous circulation in every case prior to surgery, whilst the tourniquet remained deflated. The plasma bupivacaine levels were less than that associated with toxicity, except in one case exhibiting signs of minor toxicity (bupivacaine plasma level 1.99 micrograms/ml-1). Reasons for the leak in spite of a well-conducted technique are discussed.     

Intravenous regional anaesthesia below the knee

The quality of anaesthesia provided by three dosages of prilocaine, 40 ml 0.5%, 20 ml 1%, or 40 ml 1%, administered in random order, for intravenous regional anaesthesia of the lower extremity below the knee was compared in six volunteers. Limited sensory blockade was achieved in the groups with 40 ml 0.5% and 20 ml 1% during the 30-minute test period. One subject was not fully anaesthetised with any of the dosages used. Recovery was rapid (mean 12-13 minutes) in these two groups. In two subjects given 40 ml of 1%, complete recovery took 90 minutes. At 30 minutes, the degree of flexion remaining in the great toe (control 100%) was 4% in the groups who received 40 ml of 0.5% and 1%, but 34% in those who received 20 ml of 1% respectively. Full motor recovery was achieved in 8-9 minutes. Five of six volunteers who received the 400-mg dose experienced subjective signs of central nervous system side effects when the cuff was released. In this group, the mean plasma level of prilocaine at 2 minutes was 1.22 micrograms/ml, maximum 2.12 micrograms/ml. In a radiological examination, no leak of contrast medium under the tourniquet cuff (300 mmHg) was detected. The development of anaesthesia was fastest following the largest dose, but the large number of central side effects makes that dosage less suitable for clinical work.     

Intravenous regional anaesthesia with 0.5% prilocaine or 0.5% chloroprocaine

Ten healthy male volunteers received intravenous regional anaesthesia of the upper limb on two separate occasions using 40 ml of 0.5% prilocaine or 40 ml plain 0.5% chloroprocaine by random allocation. Using a double-blind method, the onset and recovery of sensory block was tested (pinprick) in the four main nerve areas. The onset and recovery of motor block was measured by squeezing a rubber balloon connected to a manometer. The symptoms after deflation of the tourniquet were recorded. Seven volunteers in both groups developed total anaesthesia in 20 min. Complete motor block occurred in 12.3 min with prilocaine and 11.3 min with chloroprocaine. Sensation recovered in all areas in 7.6 min with prilocaine and 10.0 min with chloroprocaine (ns). Motor function recovered in 8.4 and 12.0 min respectively (p less than 0.01). Six volunteers in the chloroprocaine group showed signs of venous irritation and/or antecubital urticaria in the test arm for 30-45 min after the deflation. Four volunteers in the chloroprocaine group had increased in heart rate (greater than 20%) and one of them short periods of junctional rhythm during the first 2 min after tourniquet deflation. Mild, short-lived CNS side effects occurred in both groups.     

Intravenous regional anaesthesia of the arm

The effects of different techniques of exsanguination of the upper arm during intravenous regional anaesthesia on prilocaine plasma concentrations, quality of anaesthesia, toxic symptoms after deflation of the tourniquet and injection pressure of the anaesthetic were studied in 10 healthy male volunteers. The nondominant arm was exsanguinated using either Esmarch's bandage or elevation of the arm for 2 minutes plus arterial occlusion by compression of the brachial artery. The injection pressure after the prilocaine dose (3 mg/kg) was significantly higher in the elevation group (maximally 98 mmHg). There were no statistically significant differences in the onset of, or recovery from, anaesthesia between the groups. Various mild toxic symptoms were experienced in the central nervous system after deflation of the tourniquet. However, there was no correlation between the two techniques and the degree of severity of the toxic symptoms. The highest single venous plasma concentration (total) of prilocaine was 2.3 micrograms/ml measured from the contralateral cubital vein (elevation group, 2 minutes). The differences in prilocaine concentrations between the groups were not statistically significant.     

Intravenous regional anaesthesia with ketamine

Ketamine, 40 ml 0.5% solution, was used in the technique of intravenous regional anaesthesia in 14 patients undergoing upper limb surgery. Satisfactory analgesia was obtained in 12 of the patients. The method is limited by the fact that all patients became unconscious within a few minutes of tourniquet release, and that this could not be prevented by naloxone.     

Intravenous regional analgesia with prilocaine for foot surgery

Intravenous regional analgesia for foot surgery with an ankle tourniquet was used for 48 cases. Prilocaine 0.5% 3 mg/kg body weight was injected either quickly over about 2 minutes or slowly over about 5 minutes. The tourniquet was inflated either to occlusion pressure plus 100 mmHg or to occlusion pressure plus 200 mmHg. Plasma prilocaine levels were measured while the tourniquet remained inflated and after release of the tourniquet. All four techniques resulted in a low incidence and magnitude of prilocaine leak and low prilocaine plasma levels after tourniquet release. The data suggest that slow injection with the high tourniquet inflation pressure is better, although the differences in leakage with an intact tourniquet were not statistically significant. Excellent analgesia was achieved in over 90% of patients and there were no complete failures. No dangerously high prilocaine plasma levels were produced and no serious side effects observed.     

Bupivacaine and prilocaine in intravenous regional anaesthesia

Six volunteers underwent intravenous regional anaesthesia of the non-dominant arm on four occasions using two equipotent doses of bupivacaine and prilocaine, administered in a randomised double-blind sequence. Equipotent doses produced similar degrees of motor and sensory blockade. Bupivacaine produced more rapid motor power loss and delayed motor recovery (p less than 0.01). Prilocaine produced more prolonged objective blockade following tourniquet release (p less than 0.01), although this was not clinically useful, and bupivacaine led to a marked prolongation of subjective blockade (p less than 0.01). Increase of dose with both drugs gave more rapid and complete sensory and motor blockade and delayed recovery (p less than 0.05). This was, however, associated with more marked toxicity. It is suggested that in intravenous regional anaesthesia there are no clinical differences between the drugs in equipotent solutions, and that the lower concentrations are the appropriate ones for standard use.     

Intravenous regional analgesia – a new modification

A modification of the standard intravenous regional analgesia technique is described whereby excess local anaesthetic solution is removed from the veins of the isolated arm once analgesia has been established. This simple procedure was shown to reduce the incidence of oozing at the site of operation without affecting the quality of analgesia. Measurement of the quantity of local anaesthetic agent removed from the isolated arm 15 min after injection revealed that the amounts removed were small, indicating rapid uptake and binding in the tissues. This would imply that removal of excess local anaesthetic agent from the isolated arm after 15 min does not confer added safety as regards reducing the risk of leakage of agent into the general circulation in the event of cuff failure.     

Alkalinisation of prilocaine for intravenous regional anaesthesia

Ten volunteers underwent intravenous regional anaesthesia on two separate occasions using 40 ml prilocaine 0.5% to which was added 5 ml of either saline 0.9% or sodium bicarbonate 8.4%. Addition of sodium bicarbonate decreased the time of onset of loss of sharp touch and temperature sensations and of motor power. Time to full recovery of the arm was slower with the alkalinized solution and nine of the subjects preferred this block. The addition of sodium bicarbonate to prilocaine for intravenous regional anaesthesia may be clinically useful.     

The effects of injected solution temperature on intravenous regional anaesthesia

Ten healthy volunteers received three standard Bier's blocks. Prilocaine 0.5%, 40 ml was injected at a solution temperature of 0 degrees C, 22 degrees C or 37 degrees C. Recordings were made of sensory block, motor block, intravenous pressure, limb temperature and pain on injection. There were no differences between the three treatments in the rate of development or in the quality of block but there was a significant difference in the comfort of injection. Cold solutions caused most, and warm solutions least discomfort.     

Alkalinisation of prilocaine for intravenous regional anaesthesia. Suitability for clinical use

Eighty unpremedicated patients undergoing day-case hand surgery under intravenous regional anaesthesia were randomly allocated to receive, in a double-blind study, either 40 ml 0.75% prilocaine hydrochloride, with 5 ml 8.4% sodium bicarbonate or 5 ml 0.9% saline. The alkalinised group had significantly less pain on injection (p = 0.0045), during surgery (p = 0.0074) and 5 minutes after the tourniquet was deflated (p = 0.0027). The time elapsed between insertion of the block and commencement of surgery was not affected.     

Regional anaesthesia for ophthalmic surgery

Ophthalmic surgery can be conducted under local anaesthesia (LA), with techniques ranging from topical anaesthetic drops to sharp needle regional blocks. The sub-Tenon's block is the most common regional technique in current practice superseding sharp needle techniques (e.g. retrobulbar block). A sub-Tenon's block is a safe and effective means of providing analgesia, anaesthesia and good operating conditions.     

Addition of fentanyl to prilocaine for intravenous regional anaesthesia

Fifteen volunteers underwent intravenous regional anaesthesia on two occasions using 40 ml 0.5% prilocaine, to which had been added either 2 ml 0.9% saline or 0.1 mg fentanyl (resultant concentration 2.5 micrograms/ml). There was no difference in the rate of onset of blockade of cold sensation from an ethyl chloride spray, or to sharp and touch pinprick sensation in either group. There was an increase in the incidence of nausea after tourniquet release in the fentanyl group. It is concluded that the addition of fentanyl 2.5 micrograms/ml to prilocaine 0.5% confers no benefit in intravenous regional anaesthesia.     

Fentanyl-prilocaine mixture for intravenous regional anaesthesia in patients undergoing surgery

The effect of the addition of 0.1 mg or 0.2 mg fentanyl to 40 ml 0.5% prilocaine in intravenous regional anaesthesia of the arm was investigated in 37 patients in a randomised, double-blind study. The characteristics of the sensory and motor block were studied. There was no difference in the speed of onset of analgesia in the groups (mean latency approximately 4 min in each group). However, significantly more patients in the fentanyl 0.2 mg group (7/12) had complete anaesthesia at 15 min than in the fentanyl 0.1 mg group (1/13) and the control group (2/12) (p less than 0.05). There were no differences in the incidence of tourniquet pain immediately before cuff deflation (tourniquet time 45-87 min). After cuff deflation, in those patients who complained of wound pain within 30 min, on average the pain appeared later in the fentanyl 0.2 mg group (six patients, mean 14.3 min) than in the control group (eight patients, mean 9.4 min) (ns). In the fentanyl groups, the incidence of central nervous system side effects was greater than in the control group (fentanyl 0.1 mg 7/13 patients, fentanyl 0.2 mg 6/12 patients, control 1/12 patients) (p less than 0.05). The plasma concentrations of prilocaine after cuff deflation were higher, in a dose-dependent fashion, in the fentanyl groups than in the control group, but the concentrations of prilocaine and fentanyl did not correlate with the symptoms. Postoperative nausea occurred only in the patients who had received fentanyl.     

Future of regional anaesthesia

The development and refinement of regional anaesthetic techniques for various types of surgery, mainly obstetric, ophthalmic and orthopaedic surgery, and of continuous regional analgesia continues. Suitable analgesic drug mixtures, and concentrations, will be further tested in order to find the ideal analgesic regimen for each type of surgery and for the individual patient. No new local anaesthetics or equipment for clinical use are expected in the near future. Improvement therefore depends much on how the anaesthesiologists use the present drugs, needles, nerve detection devices, catheters and pumps. During training in regional anaesthesia for the speciality of anaesthesiology and intensive care medicine, it may suffice to concentrate only on certain common techniques such as epidural block, spinal block, axillary brachial plexus block, intravenous regional anaesthesia and femoral nerve block. Rare regional anaesthetic blocks and invasive techniques should be mastered and taught by specially trained regional anaesthesiology experts. In chronic pain, regional anaesthetic blocks with local anesthetics are not expected to play any major therapeutic role. However, nerve blocks can be useful for diagnostic purposes and in order to facilitate rehabilitation in chronic pain syndromes.