Chapter 41. Intravenous Regional Block for Upper & Lower Extremity Surgery

The technique of intravenous regional anesthesia (IVRA) was first introduced by August Bier in 1908.1 Bier block essentially consists of injecting local anesthetic solutions into the venous system of an upper or lower extremity that has been exsanguinated by compression or gravity and that has been isolated by means of a tourniquet from the central circulation. In Dr. Bier's original technique, the local anesthetic procaine in concentrations of 0.25% to 0.5% was injected through an intravenous cannula, which had been placed between two Esmarch bandages utilized as tourniquets to divide the arm into proximal and distal compartments.2–4 After injecting the local anesthetic, Dr. Bier noted two distinct types of anesthesia; an almost immediate onset of “direct” anesthesia between the two tourniquets, and then, after a delay of 5 to 7 min, an “indirect” anesthesia distal to the distally placed tourniquet. By performing dissections of the venous system of the upper extremity in cadavers after injecting methylene blue, Bier was able to determine that the direct anesthesia was the result of local anesthesia bathing bare nerve endings in the tissues, whereas the indirect anesthesia was most probably due to local anesthesia being transported to the substance of the nerves via the vasa nervorum, where a typical conduction block occurs. Dr. Bier's conclusion was that two mechanisms of anesthesia were associated with his technique: peripheral infiltration block and conduction block. The technique, as originally described by Dr. Bier, remains essentially unchanged in modern practice for the past 95 years, except for the introduction of the double-tourniquet preparation used in current clinical practice5–7 (Figure 41–1).

Bier block can be used for brief surgical procedures or manipulations of the upper or lower extremity. However, the technique found its greatest acceptance for use for the upper extremity because tourniquet problems and other safety issues seem to arise more frequently when IVRA is used on the lower extremities. Bier block is also a procedure that has found utility as a treatment adjunct for patients suffering from complex regional pain syndromes (CRPS) (formerly know as reflex sympathetic dystrophy, or sympathetically maintained pain) as an alternative to repeated sympathetic blocks. In this regard, IVRA has been shown to decrease neurogenic inflammation, a phenomenon possibly associated with CRPS, with little impairment of sensory function, at least when mepivacaine is the local anesthetic chosen for the block. Sensibility to cold is significantly decreased 10 and 30 min after the block, even with a reduction in the skin temperature on the blocked side.8 Chemical sympathectomy using IVRA with agents such as guanethidine or bretylium may last up to 5 days, as compared with local anesthetic blocks, which typically provide analgesia lasting only several hours. Quantitative sensory testing before and after such blocks has demonstrated that it is possible to predict which patients will have long-lasting pain alleviation using IVRA guanethidine blocks following traumatic injury or surgery.9

Although IVRA is a safe and effective method of administering local anesthetics for extremity block both for surgery and for pain control, one recent large survey noted that most third-year (CA-3) anesthesia residents had performed fewer than 10 such blocks during the entire course of their training.10

The only relevant anatomy is the location and distribution of the veins of the hand, antecubital fossa, and of the foot and ankle region.

Upper Extremity

IVRA is appropriate for surgeries and manipulations of the extremities requiring anesthesia of up to an hour's duration. It is most suited for peripheral, soft-tissue operations such as ganglionectomies, carpal tunnel release, Dupuytren's contractures, or reduction of fractures. However, the necessity of exsanguinating the extremity using an Esmarch bandage, a potentially painful maneuver, may preclude certain procedures from being undertaken with this technique (see Figures 41–5, 41–6, and 41–10). Likewise, manipulations of the ulnar, median, or radial nerves may cause paresthesias, which may require the use of analgesics or sedatives. A novel use of IVRA is for anesthetizing the hand prior to injecting botulinum toxin A (BTX-A) for the treatment of hyperhidrosis. BTX-A significantly reduces sweat production, as measured by Minor's test and as quantified by corneometer analysis, but the injection is painful unless the hand is anesthetized beforehand; IVRA has been found to be very suitable for this purpose.11 IVRA of the upper extremity has been occasionally utilized for prolonged analgesia/anesthesia, with a mandatory tourniquet deflation period of at least 1 min prior to reestablishing the anesthetized state.12

Lower Extremity

IVRA may be used for brief surgical interventions of the lower extremity in a manner analogous to that described earlier for upper extremity surgery. Surgical procedures that may be completed using this approach include excision of a mass, digital nerve repair, phalangeal fracture/dislocation surgery, and accessory navicular excision. Any foot, ankle, or distal lower extremity orthopedic procedure requiring approximately 45 min or less may be amenable to this modality. Although IVRA has been associated with an increased incidence of compartment syndrome when treating tibial shaft fractures, and has therefore been deemed contraindicated in such cases, a recent study in volunteers showed no significant difference in tissue pressures before and after tourniquet inflation regardless of the volume of saline used (≤1.5 mL/kg) or as a function of time following saline injection during tourniquet inflation. The authors concluded that in the normal atraumatic limb, simulated IVRA using normal saline (NS) does not increase tissue pressure within the anterior compartment of the leg.13

Pediatrics

IVRA has been an acceptable choice in selected pediatric patients for the reduction of fractures of the upper extremity. One large study of 470 children ages 2–19 years found that IVRA was adequate for fracture reduction in 99% (467 total). No complications were noted. The technique was only aborted in three children due to failure to gain peripheral venous access.15 However, the technique of IVRA was found not to be superior to administration of nitrous oxide for the same purpose in a smaller sample of 28 children. Additionally, the nitrous oxide use was more rapidly applicable and dissipated more readily.16

The only absolute contraindication to IVRA is patient refusal. Relative contraindications include:

• Crush injuries of an extremity
• Inability to locate peripheral veins
• Local skin infections
• Cellulitis
• Compound fractures
• Patients with convincing history of allergy to local anesthetics
• Patients with severe vascular injuries to the extremity
• Preexisting vascular arteriovenous shunts and patients in whom a tourniquet is unsuitable (ie, patients with severe peripheral vascular disease)

(Figures 41-1, 41-2, 41-3, 41-4, 41-5, 41-6, 41-7, 41-8, 41-9, 41-10, and 41-11)

1. 1. Local anesthetic agents: Lidocaine HCl, 0.25–0.5% (alternative is prilocaine, 0.5%)

2. 2. One rubber tourniquet (Penrose drain) 12–18 in. in length (30–45 cm) and ⅞ in. wide (2.3 cm) for use prior to placing the intravenous cannula (see Figures 41–7 and 41–11)

3. 3. One 18- or 20-gauge intravenous (IV) extracatheter (catheter-over-needle) (see Figures 41–2 and 41–11)

4. 4. One 500-mL or 1-L bag of IV solution connected to an infusion set (vs a Hep-Lock) to be connected to the IV cannula to maintain its patency until the anesthetic solution is injected in the isolated extremity (may substitute a saline-flushed IV port instead)

5. 5. Standard American Society of Anesthesiologists (ASA) monitors (electrocardiograph, blood pressure, pulse oximeter)

6. 6. Resuscitation equipment (IV catheter, crystalloid solution, and infusion set for the contralateral upper extremity) (for upper extremity IVRA)

7. 7. A functional IV catheter, crystalloid solution, and infusion set for the contralateral upper extremity

8. 8. Two pneumatic tourniquets of appropriate size for the selected extremity (see Figures 41–1, 41–3, 41–4, 41–5, 41–6, 41–9, and 41–10)

9. 9. One Esmarch bandage 60 in. in length (152 cm) and 4 in. wide (10 cm) for exsanguinating the arm (see Figures 41–5, 41–6, and 41–10)

10. 10. Sterile skin preparatory set

11. 11. Fifty-milliliter Luer-Lok syringe (see Figures 41–7 and 41–11)

12. 12. One graduated measuring cup for the mixing of solution, preferably with a 100-mL capacity

13. 13. Adhesive tape; various sizes

The patient lies in the dorsal recumbent position or in any other position as long as the vein selected for placement is readily accessible. The resuscitative equipment is checked, and the pneumatic tourniquets are tested and prepared for use. For surgery on the elbow, the needle will be placed in the forearm or antecubital fossa. For procedures on the hand or forearm, a vein on the dorsum of the hand is best selected (see Figure 41–2).

For lower extremity procedures, a vein in the foot, ankle, or lower leg is chosen (see Figure 41–11). After obtaining intravenous access in a nonoperated extremity (alternatively, a central venous access may be secured), a full complement of ASA monitors is applied and baseline vital signs are assessed. If the patient is in severe pain, small aliquots of IV analgesics may now be administered (ie, fentanyl 1–2 mcg/kg) to facilitate the exsanguination process. Since total patient cooperation is not essential to be successful, small doses of a water-soluble benzodiazepine (ie, midazolam 15–25 mcg/kg) may alternatively be administered for anxiolysis. An important benefit to choosing a benzodiazepine is the suppression of the convulsant response associated with local anesthetic toxicity, a valid concern in the patient undergoing IVRA due to the large volume of agent being directly administered into the vascular system.

Upper Extremity IVRA

The following is the technique of IVRA for upper extremity procedures as previously taught at Cook County Hospital by Alon P. Winnie, MD.

1. 1. A double pneumatic tourniquet is placed on the proximal cuff high on the upper arm (see Figures 41-3, 41-4, 41-5, and 41-6)

2. 2. An indwelling plastic extracatheter is inserted into a peripheral vein as far distally as feasible.

3. 3. The entire arm is elevated, and a rubber Esmarch bandage is wound around the arm spirally from the hand to the distal cuff of the double tourniquet to exsanguinate the arm (see Figures 41–5 and 41–6).

4. 4. The axillary artery is digitally occluded, and while pressure is maintained on it, the proximal pneumatic cuff is inflated to 50–100 mm Hg above the systolic arterial blood pressure, after which time the Esmarch bandage is removed.

5. 5. Following inflation of the proximal cuff and removal of the Esmarch bandage, 30–50 mL of 0.5% lidocaine HCl is injected via the indwelling plastic catheter, the volume depending on the size of the arm being anesthetized (see Figure 41–7).

6. 6. After injection of the local anesthetic, the arm is brought down to the level of the procedure table, the IV cannula in the surgical extremity is withdrawn, and pressure is quickly applied over the site using sterile povidone–iodine (Betadine)-soaked sponges (see Figure 41–8).

7. 7. About 25–30 min after the onset of anesthesia or when a patient complains of tourniquet pain, the distal cuff is inflated and the proximal cuff is deflated, to minimize the development of tourniquet pain.

Lower Extremity IVRA

The only significant difference is that the IVRA technique for the lower extremity requires relatively larger volume of local anesthetic. This is necessary to more completely fill the larger vascular compartment of the lower extremity from the distally placed IV cannula to the proximal tourniquet (100 mL vs 50 mL) (see Figures 41-9, 41-10, and 41-11).

Local Anesthetic Considerations

Lidocaine is the prototypical local anesthetic used for IVRA in the United States. In Europe, however, prilocaine has been the subject of most clinical trials to date. Attempts have been made to maximize the efficacy of lidocaine, while minimizing side effects or toxicity of the agent. Alkalinization of 0.5% lidocaine (using 1.4% sodium bicarbonate) for IVRA was studied in 31 patients. The authors found no clinical advantage to the practice of alkalinization of lidocaine with respect to sensory block, motor block, or the appearance of postoperative pain.22 When lidocaine was compared with alkalinized and nonalkalinized 2-chloroprocaine, both used as 0.5% concentrations and used for hand surgery, alkalinized chloroprocaine behaved similarly to lidocaine, but plain chloroprocaine offered no benefit and produced more minor side effects than seen with lidocaine.23 Lidocaine has been compared with ropivacaine for upper extremity IVRA in two separate studies. Two doses of ropivacaine (1.2 and 1.8 mg/kg) were compared with one dose of lidocaine (3.0 mg/kg) in 15 volunteers. Recovery of sensory and motor block after tourniquet release was slowest with the high-dose ropivacaine group. More patients in the lidocaine group (5 out of 5) experienced light-headedness following tourniquet release, vs only 1 in the high-dose ropivacaine group.24 In the second study, 51 patients were randomized to receive either ropivacaine 0.375% or lidocaine 0.5% in a volume of 0.4 mL/kg up to 25 mL. Postoperative analgesia as measured by first request for analgesics was superior in the ropivacaine group.25

Prilocaine has been compared with lidocaine, as well as with other local anesthetics used for IVRA. Forty milliters of 0.5% prilocaine (100 mg) was compared with the same volume and same concentration of chloroprocaine in 10 volunteers undergoing IVRA, while evaluating onset of sensory and motor block. Motor block onset did not differ between groups, and sensation recovered almost equally well. However, recovery of motor function was shorter in the prilocaine group, and more chloroprocaine patients demonstrated signs of venous irritation or antecubital urticaria for 30–45 min after tourniquet deflation. Heart rate changes were also more notable in the chloroprocaine group.26 The same group of investigators expanded their study to include 60 patients; 30 in each of the two respective groups detailed earlier. Now, the investigators found that complete recovery of sensory block was faster in the prilocaine group (7.1 vs 9.8 min). Otherwise, the incidence of side effects remained higher in the chloroprocaine group.27 Next, these investigators compared 0.5% prilocaine with the same concentration of articaine (a newer amino amide–type local anesthetic that contains thiophene and that is pharmacologically similar to mepivacaine) for upper extremity IVRA. Articaine, a potent local anesthetic with a low degree of toxicity by virtue of its rapid metabolism with esterases, was felt to be a suitable alternative to prilocaine. Ten volunteers participated in this double-blinded, crossover comparison of the two agents. They found no significant difference between the two with respect to onset of anesthesia or motor block, or in recovery of sensory or motor function. However, 80% of the subjects experienced skin rashes after receiving articaine, vs 20% in the prilocaine group.28 When 0.5% prilocaine was compared with the same concentrations of articaine or lidocaine in three groups of 10 patients each for IVRA, it was found that the onset of sensory block was significantly shorter in the articaine group, which also had the lowest peak plasma concentrations of local anesthetic following tourniquet release.29 Plain prilocaine 1% has been compared with the same local anesthetic combined with four different additives for IVRA; bupivacaine 0.25%, clonidine 150 mcg, sufentanil 25 mcg, or tenoxicam 20 mg. The sufentanil-added group demonstrated the most rapid onset of sensory block; postoperative pain scores were improved by adding either clonidine or tenoxicam. Otherwise, there were no significant differences among the five groups with respect to onset and duration of sensory and motor block.30 Unlike the situation noted for lidocaine with the addition of bicarbonate as an adjuvant, the addition of bicarbonate to prilocaine does seem to shorten onset time and prolong the duration of anesthesia.31,32

The use of mepivacaine for IVRA has been studied. Sixteen patients were evaluated using 1.4 mg/kg in 40 mL for IVRA vs saline IVRA blocks performed in the same individuals on the contralateral arm. Arterial occlusion was maintained for 20 min. Reactive hyperemia was attenuated in the mepivacaine-treated arm for the 60-min evaluation period, indicating that mepivacaine is a potent vasoconstrictor of long duration of action. This finding has implications for the use of mepivacaine in individuals with either compromised upper extremity blood flow, or in those suffering from CRPS, wherein it probably should not be considered the local anesthetic of choice.33 The same study group evaluated the effects of mepivacaine IVRA on intracutaneous capsaicin-induced burning pain and on microvascular skin blood flow as measured by Doppler perfusion imaging. The reactive hyperemia was less in the mepivacaine-treated arm 10 min after tourniquet release, and the area of the flare was smaller after capsaicin in the mepivacaine-treated arms. The authors concluded that mepivacaine IVRA had no effect on post-IVRA sensory function of thin afferents, but differentially decreased the spread of capsaicin-induced flare.34

Adjuncts to Local Anesthetics for IVRA

A systematic review of the literature was undertaken to evaluate the use of adjuncts to local anesthetics for IVRA. Twenty-nine studies met the criteria of being randomized, double-blinded, and controlled. Data on 1217 study subjects were reviewed, and the agents studied included opioids (fentanyl, sufentanil, meperidine, morphine), clonidine, muscle relaxants (atracurium, pancuronium, mivacurium), tramadol, nonsteroidal antiinflammatory agents (NSAIDs) (ketorolac, tenoxicam, acetylsalicylate), alkalinization using sodium bicarbonate, and the addition of potassium, and temperature alterations. The authors found solid evidence supporting the use of NSAIDs in general, and ketorolac in particular, for improving postoperative analgesia. Clonidine 1 mcg/kg also appeared to improve postoperative analgesia and prolong tourniquet tolerance. Opioids fared poorly when used for IVRA, with only meperidine in doses of ≥30 mg showing substantial postoperative benefit at the expense of postdeflation nausea, vomiting, and dizziness. Muscle relaxants improved postoperative motor block and were beneficial in fracture reduction in which muscular relaxation is imperative for good results.35

Alpha2-Agonists (Clonidine and Dexmedetomidine)

Clonidine has been added to both prilocaine and lidocaine as an adjunct to IVRA, both for surgery and for the management of CRPS. When 2 mcg/kg was added to prilocaine 0.5% in a randomized, double-blind fashion in 56 patients undergoing upper extremity surgery, there was no difference between groups regarding sensory or motor block onset or duration. The patients who had clonidine added had a significant reduction in arterial blood pressure after tourniquet release (24–48%), while heart rate remained unchanged. The authors concluded that clonidine was of limited benefit as an adjunct to IVRA local anesthetics.36 When a dose of 1 mcg/kg in a total volume of 50 mL of 0.5% lidocaine was used for lower extremity IVRA for patients suffering from CRPS, five of seven subjects obtained complete pain relief after four to six blocks. The remaining two study patients derived partial benefit from the blocks. There were no cases of significant hypotension, bradycardia, hypoxemia, or excessive sedation.37 The addition of clonidine to prilocaine did dramatically suppress tourniquet pain, but it did not alter postoperative pain following tourniquet deflation.38 Dexmedetomidine is approximately eight times more selective toward the α2-adrenoreceptors than is clonidine. As such, it has been used in IVRA to determine if it might advance some of the beneficial findings noted with the latter agent. Thirty patients undergoing hand surgery under IVRA received 0.5% lidocaine alone or lidocaine plus dexmedetomidine 0.5 mcg/kg. The dexmedetomidine group showed a more rapid onset of sensory and motor block, a prolonged sensory and motor block recovery, prolonged tolerance for the tourniquet, and improved quality of analgesia compared with the group that received local anesthetic only.39

Opioids

Since opiate receptors were discovered to exist in the peripheral nervous system40,41 and with the demonstration that opioids may produce effective, long-lasting analgesia when injected in conjunction with local anesthetics for brachial plexus block,42–46 several investigators have attempted to decrease the potential for toxicity from local-anesthetic-only IVRA by adding opioids to reduce the concentration of lidocaine. Although it has not been proven that the addition of fentanyl to lidocaine for IVRA results in improved analgesia while reducing the risks,47,48 the addition of fentanyl in 200-mcg doses to prilocaine 0.5% did result in more complete anesthesia than in patients who had 100 mcg added, or when plain prilocaine was used for IVRA. Postoperative nausea and central nervous system side effects were higher in the fentanyl-added groups vs those who received local anesthetic alone.49 Two other studies, however, found that the addition of opioids to prilocaine did not improve success with the technique.50,51 More research on the effects of the addition of opioids to prilocaine for IVRA may ultimately resolve this apparent discrepancy.

Some investigators have found that adding opioid and muscle relaxants to 0.25% lidocaine provides the same analgesia and muscular relaxation as that provided by 0.5% lidocaine alone, while reducing the likelihood of systemic toxicity. Adjuvants added to lidocaine have included fentanyl 50 mcg plus pancuronium 0.5 mg,52,53 fentanyl plus rocuronium,54 and fentanyl plus d-tubocurarine.55 In each case, the authors reported outstanding operating conditions, and since the lidocaine concentration was able to be reduced to 0.20%, the potential for systemic toxicity was at least halved.

When meperidine 0.25%, 40 mL (100 mg), was used as a solitary agent for IVRA, complete motor block was produced, just as effective as that produced by lidocaine. Motor block onset was as rapid or more rapid than sensory block onset in each of the 15 patients in this study group. However, when compared with plain lidocaine in this study, there was a higher incidence of dizziness, nausea, and pain at the injection site.56

Tramadol

Tramadol has been evaluated for use in IVRA of the upper extremity. Sixty volunteers divided into four groups of 15 patients each received IVRA with 40 mL of tramadol 0.25% (100 mg), 0.9% NS, lidocaine 0.5%, or lidocaine plus tramadol 0.25%. The onset and recovery of sensory and motor block was similar between the tramadol and NS-only groups. However, the addition of tramadol to lidocaine resulted in faster onset of sensory block at the expense of an increase in skin rash development and painful burning sensations at the injection site. The conclusion of the authors was that tramadol alone does not possess local anesthetic effects, but might modify the effect if added to a local anesthetic like lidocaine.57 In another study comparing 0.5% lidocaine with and without 50 mg of tramadol for upper extremity IVRA, the tramadol-added group experienced less tourniquet pain than the local-only group, but, as in the study mentioned earlier, there were several cases of skin urticaria in the tramadol group, but not in the lidocaine-only group.58 Tramadol (100 mg) added to lidocaine for IVRA for upper extremity anesthesia acted similarly to sufentanil (25 mcg) or clonidine (1 mcg/kg) added to the local anesthesia with respect to intraoperative hemodynamic data, time to recovery of sensory block, onset and recovery of motor block, sedation scores, and postoperative pain.59 In summary, tramadol is ineffective as a solo agent for IVRA, but may confer some advantage when added to lidocaine. This advantage, however, may be offset by the significant incidence of dermatologic side effects of tramadol given intravenously in an exsanguinated extremity.

Muscle Relaxants

A small dose of nondepolarizing muscle relaxant may be chosen as an adjunct to the local anesthetic administered for IVRA; however, since d-tubocurarine releases histamine even in judicious doses, it is probably best to avoid this agent altogether. Atracurium has been added to lidocaine in an effort to improve muscular relaxation during IVRA, particularly during the reduction of upper extremity fractures and dislocations. Adding 3 mg of atracurium to lidocaine for IVRA resulted in a decrease in the onset time of analgesia in the hand, but not at the tourniquet site. There was no added benefit to adding this agent, or adding alfentanil to lidocaine in the same study.60 A prior study using 2 mg of atracurium added to 40 mL of 0.5% lidocaine for IVRA for hand surgery in 40 patients randomized to one of two groups found that the addition of the atracurium provided a greater degree of muscular relaxation, easier reduction of fractures, and better operating conditions, as well as less pain after surgery.61

Neostigmine

Neostigmine has been suggested as a co-analgesic when used for epidural and intrathecal analgesia and anesthesia, but evidence of its benefit in the peripheral nervous system is controversial. In two studies, one using neostigmine added to lidocaine, and the other using the adjuvant added to prilocaine, there have been conflicting findings. When neostigmine (1 mg) was added to 0.5% lidocaine for IVRA in a study of 54 volunteers randomized into one of three study groups, it was found that the addition of the adjuvant provided no benefit in terms of analgesia or anesthesia compared with controls.62 When one-half the dose of neostigmine (0.5 mg) was added to prilocaine (3 mg/kg) for IVRA in 30 patients randomized to one of two treatment groups, it was found that the adjuvant group demonstrated shortened sensory and motor block onset times, prolonged sensory and motor block recovery times, improved quality of anesthesia, and prolonged time to first analgesic requirement vs the plain prilocaine group.63 It appears that these conflicting findings with neostigmine added to two distinct local anesthetics for IVRA will need to be confirmed by additional work incorporating larger patient sample sizes to resolve the apparent discrepancy in the two small studies mentioned earlier.

Nonsteroidal Antiinflammatory Agents

Other attempts to improve IVRA with lidocaine have included using NSAIDs like ketorolac64 to suppress tourniquet pain while enhancing postoperative analgesia. Although ketorolac has shown some efficacy, other NSAIDs have not fared as favorably. Ketorolac has been added to lidocaine for IVRA for the treatment of sympathetically mediated pain syndromes. In a retrospective review of 61 patients referred to a university pain center with a diagnosis of reflex sympathetic dystrophy (RSD) who all underwent IVRA with the combination of ketorolac-lidocaine, 26% (16/61) had a complete analgesic response to the block(s). Forty-three percent (26/61) had a partial response, and 31% had no response. The authors stated that the only symptom predicting failure was the presence of allodynia. However, allodynia is the hallmark of RSD, so one must wonder whether the clinicians correctly categorized the patients as being afflicted with RSD, vs an alternative diagnosis.65 When used for upper extremity surgery, ketorolac added to lidocaine for IVRA was shown to be safe and effective, and furthermore, using a forearm tourniquet instead of an upper arm tourniquet in this study demonstrated that the dose of both agents could be reduced by 50%, while also providing for prolonged sensory block and prolonged postoperative analgesia. Twenty milligrams of ketorolac was added to lidocaine 0.5% for the upper arm tourniquet group, and half the dose of both agents (by virtue of halving the volume administered of an equipotent concentration of both drugs) was used in the forearm tourniquet group.66

Another NSAID, tenoxicam, was added to prilocaine in one study of 45 total patients. A 20-mg dose of the NSAID was used in patients undergoing IVRA for reduction of Colles' fractures, with patients divided into three groups. One group received local anesthetic only, one received local plus tenoxicam, and one group had IVRA with local anesthetic only plus IV NSAID. In this last group, the tenoxicam (20 mg) was injected into the contralateral arm, opposite the IVRA procedure arm. The group receiving the NSAID added to the local had superior analgesia and lower pain scores than either of the other two groups of patients.67

Other Specific Agents: Corticosteroids

The antiinflammatory properties of steroids have been evaluated when these agents have been added to local anesthetics for IVRA in patients with rheumatoid arthritis (RA). In a randomized, double-blind, crossover, placebo-controlled study, 20 RA patients received either 50 mg methylprednisolone in mepivacaine 0.25% or mepivacaine plain for upper extremity IVRA. The other extremity received the opposite treatment. One week later, the same medications were injected into the contralateral extremities, respectively. Fifty percent of patients reported subjective improvement at 1 and 6 weeks; objective parameters like grip strength did not change until the 6-week evaluation, at which time a significant increase was noted, as was the reduction in grip diastasis and movement-invoked pain. This report suggests that corticosteroids administered by IVRA may provide sustained analgesia in certain RA sufferers.68 Steroid IVRA has also been used as adjunctive treatment of CRPS type I. Methylprednisolone (40 mg) was added to lidocaine for IVRA in a randomized, double-blinded, placebo-controlled fashion in 22 patients. Treatments were applied once per week, for up to three sessions of blocks. The investigators found no benefit in adding the steroid to the local with regard to improvement in pain severity or shortening the course of the disease.69

Specific IVRA Treatments for CRPS

Adrenergic blocking agents or antagonists, particularly those effective at the alpha receptor, have shown promise in the treatment of CRPS, particularly when these agents are used for IVRA. Other adrenergic adjuvants release and then subsequently prevent the reuptake of norepinephrine at the neurovascular junction. Their use in CRPS is intuitive, since the pathophysiology of the disease is suspected to include the alpha receptor and to be mediated by norepinephrine. However, there is significant controversy regarding this topic, particularly when current research is compared with the findings of studies conducted almost 40 years ago. Guanethidine, reserpine, and bretylium have all been evaluated for IVRA for CRPS. When 15 mg guanethidine was added to 0.5% prilocaine in a group of 57 patients with CRPS of the upper extremity and hand, the guanethidine was found not to be more effective than NS in treating allodynia and burning pain of CRPS, following distal radius fractures.70 These findings corroborated work done in a double-blind, randomized, multicenter study 7 years earlier. Sixty patients with RSD/causalgia received four IVRA blocks at 4-day intervals with either guanethidine or placebo in 0.5% lidocaine. Long-term, there was no difference noted between the placebo group and the guanethidine group, and only 35% of patients overall in all groups had a resolution of their pain problem.71 Bretylium has been used as well in CRPS. In a randomized, controlled trial, 0.5% lidocaine was compared with the same local anesthetic to which bretylium 1.5 mg/kg was added. A decrease in pain of ≥30% was considered significant. The bretylium-local group had pain relief for 20 ± 17.5 days, as opposed to the lidocaine-only group, wherein analgesia persisted for only 2.7 ± 3.7 days. The bretylium was far superior to the local anesthetic alone in treating CRPS in this study.72 IVRA with bretylium was utilized to demonstrate that a reduction in sympathetic tone to exercising forearm muscles would increase blood flow, reduce muscle acidosis, and attenuate reflex responses. IVRA with bretylium increased blood flow as well as oxygen consumption in the exercising forearm, although both venous potassium and hydrogen ion content were elevated during the exercise phase, implying that reflex effects are unaffected by bretylium block.73

Complications due to IV regional anesthesia may be classified either as drug- or equipment- (ie, tourniquet) related. Drug-related complications depend on the agents being administered directly into the vascular system, including local anesthetics and adjuvants. Equipment-related complications include all devices and techniques used to isolate the vascular space from the systemic circulation. Inadvertent deflation of the cuff, cuff failure, a sudden increase in venous pressure within the occluded tissue to a level higher than cuff pressure, and an intact interosseous circulation may all contribute to complications due to IVRA. Lidocaine is the most commonly utilized local anesthetic for IVRA and is therefore the agent about which most complications have been reported. Fortunately, lidocaine does not accumulate to any great extent at sodium channels at therapeutic plasma concentrations, and since it both rapidly binds to and dissociates from the channel, toxic accumulations of the drug at the channel is atypical.74,75 Excessive plasma concentrations of lidocaine, as are associated with IV boluses of large doses with a faulty tourniquet system, result in peripheral vasodilatation and diminished cardiac contractility, usually seen clinically as hypotension. The usual onset of IVRA using lidocaine in 0.5% concentrations is rapid (about 4.5 ± 0.3 min) and the termination of anesthesia once the tourniquet has been deflated is also quite rapid (5.8 ± 0.5 min).76 Usually, there are no signs or symptoms of cardiovascular or central nervous system toxicity if the tourniquet is deflated at least 30 min after the drug is injected into the venous system, although tinnitus has been noted at the 20- and 27-s postdeflation periods following standard inflation times.77 Although about 70% of the administered lidocaine dose remains within the tissues of the isolated limb after tourniquet deflation, the remaining 30% enters the systemic circulation during the ensuing 45 min.75 Much more drug is released from the tissues of the isolated limb into the circulation after tourniquet deflation if the limb is inadvertently exercised, emphasizing the importance of maintaining the previously anesthetized extremity quiescent for some time immediately following tourniquet deflation. The other commonly utilized local anesthetic used for IVRA, prilocaine, is associated with the formation of methemoglobin, which occurs about 4 to 8 h after its administration.74 Fortunately, significant methemoglobinemia has not been reported when prilocaine has been used for IVRA. Prilocaine (0.5%) administered for IVRA has an onset of analgesia of about 11 min (±6.8 min) and termination of analgesia following tourniquet deflation averages 7.2 min (±4.6 min).26 The use of this agent for IVRA appears to be extraordinarily safe. Indeed, in one survey of 45,000 prilocaine IVRA blocks, there were no serious side effects and no deaths from using this drug via this technique.78 In terms of effectiveness, prilocaine seems to be equivalent to lidocaine when used for IVRA.

When opioids are administered in combination with local anesthetics for IVRA in an attempt to prolong analgesia following cuff deflation, occasional side effects typically attributed to opioids administered systemically may be noted following cuff deflation. These include nausea, vomiting, and mild sedation.47,50 When neuromuscular blocking drugs are administered in conjunction with local anesthetics to improve surgical conditions in patients undergoing fracture reduction, there have been no reports of complications from these adjuvants.

Additionally, the tourniquet itself may be a source of complications since it may cause ischemic pain and discomfort. Systemic hypertension may result from prolonged tourniquet inflation that is sustained or prolonged. Equipment misuse or malfunction is an important, and avoidable, source of complications due to this technique. Even an intact, fully functional tourniquet may be associated with leakage of administered drugs from a supposedly isolated extremity into the systemic circulation.80,81 Lower limb IVRA has an almost 100% incidence of local anesthetic leakage from beneath the tourniquet, versus about a 25% incidence for upper extremity block.82 As a corollary to this leakage phenomenon, the use of IVRA for lower extremity analgesia has an associated high incidence of poor-quality block (almost 40% in one prospective study).83 Drug may leak past an apparently fully functioning cuff and gain access to the systemic circulation via the interosseous circulation, which is not affected by the occlusion of muscles, soft-tissues, and the accompanying vascular channels included therein. This factor has been recognized for almost 40 years, yet it does not appear to be significant in the production of complications due to IVRA.84 Tourniquet deflation after IVRA is associated with signs and symptoms of systemic local anesthetic toxicity, ranging from mild CNS-related events such as tinnitus and perioral numbness, to seizures, and finally, to devastating cardiovascular collapse. These correlate with local anesthetic concentrations in arterial blood, and not to venous concentrations.79,85 Another complication due to IVRA is tourniquet pain, which not uncommonly occurs if a double-pneumatic device is not utilized81 (see Figures 41–1 and 41–2). We recommend the use of such a tourniquet for any procedure performed using IVRA that is expected to last longer than 30 min. Even when such guidelines are followed, however, some investigators have reported untoward events occurring following tourniquet deflation after a “safe” time interval. A 47-year-old patient with a history of CRPS type I underwent an IVRA block with a combination of lidocaine and clonidine. The tourniquet was deflated after 60 min and within the ensuing 10 min, he developed partial complex seizures that were persistent.86

Very rare, isolated reports of neurologic complications, including damage to the median, ulnar, and musculocutaneous nerves, are associated with IVRA.87 The cause of such complications appears to be direct pressure of the tourniquet applied to these nerves, which subsequently exhibit histologic changes resembling crush injuries. It is recommended that tourniquet time not exceed 2 h, to reduce the likelihood of capillary and muscle damage secondary to tissue acidosis.87,88 Compartment syndrome may occur rarely following IVRA, especially when IVRA is used for reduction of long bone lower extremity fractures, and may be due both to the large volume of anesthetic injected to effect analgesia as well as to inadequate or incomplete exsanguination of the limb prior to performing the block.89,90 There is also a case report of this complication following inadvertent injection of hypertonic saline solution when local anesthetic was intended to be injected.91 A 33-year-old pregnant patient undergoing IVRA for endoscopic carpal tunnel release experienced a severe episode of phantom limb sensation after the injection of the local anesthetic. The symptoms resolved on dissipation of the IVRA.92 There is one report of the devastating necessity for amputation of the arm in a 28-year-old patient whose radial and ulnar arteries thrombosed following IVRA after a brief tourniquet occlusion time.93 Whether this resulted from unsuspected intraarterial injection of drug, a drug administration error, or perhaps an idiosyncratic drug reaction is purely speculative.

Local Anesthetic Toxicity

Although lidocaine is the most commonly utilized local anesthetic agent for IVRA in the United States, in Europe prilocaine 0.5% is more routinely chosen. Prilocaine, however, is metabolized to orthotoluidine, an oxidizing compound capable of converting hemoglobin to methemoglobin. This is usually only of concern when the dose of prilocaine exceeds 600 mg, which, even for lower extremity IVRA in which volumes as large as 100 mL are utilized, should not be attained (ie, 100 mL × 0.5% prilocaine = 500 mg). Deflation of the tourniquet after surgery is a critical step to minimizing the possibility of toxicity associated with IVRA. First, it is absolutely mandatory that the tourniquet not be deflated unless at least 3034 min has elapsed since the injection of the local anesthetic, even if the duration of surgery or of the manipulation has been very brief. If the surgery is very brief, and the patient needs to recover in a postanesthesia care unit (PACU), it is acceptable to clamp off the distal tourniquet while it is inflated, remove the patient from the operating area (with the tourniquet inflated), and transfer the patient to a monitored care setting. At no time should anyone remove the clamped tourniquet, however, until the 30-min period commencing with the injection of local anesthetic solution has elapsed. At such time, the patient should be continually monitored for at least 15 min following tourniquet unclamping in the PACU. At least one case of cardiac arrest has been reported when the tourniquet was released soon after the injection of local, where the duration of surgery was extremely short.94 Second, it is absolutely essential that the deflation of the tourniquet be accomplished in a “cyclical” fashion as follows: the cuff is deflated (after a minimum of 30 min) and is immediately reinflated. The patient is observed or questioned carefully for the occurrence of symptoms associated with local anesthetic toxicity, such as tinnitus, light-headedness, metallic taste in the mouth, etc. Obviously, signs of stimulation of the CNS may also represent local anesthetic toxicity and must be sought. If there are no such signs or symptoms after about 1 min, the cuff is once again deflated, and once again immediately reinflated for a period of about 1 to 2 min, with the patient being observed and queried for systemic local anesthetic toxicity. If none appear by this time, the tourniquet may be safely deflated and removed from the extremity. The safety of such cycled deflating/reinflating is that with each deflation, only a small fraction of the administered (and unbound) local anesthetic is allowed to enter the systemic circulation, minimizing the possibility of a sudden, sustained increase in the blood level of the local anesthetic.79

IVRA is a valuable adjunct to the armamentarium of clinicians in any specialty dealing with the acutely injured patient. The simplicity of the technique and the relative safety (if strict adherence to the previously listed protocol is maintained) make it an attractive alternative to brachial plexus block (for upper extremity surgery or manipulation) and spinal or epidural block (for lower extremity surgery or manipulation). Simply being able to identify and access a peripheral vein and apply a pneumatic tourniquet make this one of the most “user-friendly” regional block modalities in clinical practice. One of the only potential disadvantages associated with IVRA is the very finite duration of anesthesia/analgesia associated with its use. A relative inability to prolong analgesia long into the postprocedure period detracts from its utility. For those occasions, continuous catheter insertion and maintenance by way of plexus anesthesia surely offers an attractive alternative.