USE OF LOCAL ANAESTHETICS-CONTROVERSIES

Prof Anil OHRIDEPTT OF ANAESTHESIA IGMC

SHIMLA

INTRODUCTION• Contemporary anesthesiologists faced with interesting choices. Modern general

anesthesia is well accepted and efficient and has a laudable record of safety. In the past,many anesthesiologists refrained from using peripheral nerve block techniques because COMPLICATIONS AND CONTROVERSIES IN REGIONAL ANESTHESIA and of the constraints of onset time, lack of enthusiasm by surgeons, and the potential for incomplete anesthesia. Many thought that neuraxial anesthesia was more reliable and better tolerated despite the potential for intraoperative hypotension and bradycardia.

• Today, interest in regional anesthesia and in particular peripheral nerve block has increased. Many surgeons and patients accept the inconvenience associated with performing peripheral nerve block to accrue the potential benefit of an early discharge andimproved comfort.

• Observational data indicate that local anesthetic toxicity and the potential for postoperative neurologic dysfunction following regional anesthesia are rare and often unpredictable. Anesthesiologists must develop strategies to improve their confidence and success rates. Methods for evaluating complication

CONTROVERSIES

• Controversies means debate and dialogue that ensue when clinicians examine the issue of best practice.

• All methods of anesthesia care has risk,and situational controversies associated with regional anesthesia practice.

COMPLICATIONSComplications represent the unexpected or untoward events observed following the application or exposure to anesthetic agents or technTrauma associated with needles and catheters used to deliver local anesthetic solutions.

. Untoward effects of local anesthetic drugs and adjuvants instilled.• Untoward effects resulting from the anticipated or unanticipated

physiologic consequences of local anesthetic blockade.The major and minor complications associated with regional anesthesia are wellknown to clinicians and are well annotated. Complications can occur immediately orthey can be delayed.

. They can be clinically insignificant or, in rare situations, lifethreatening. Knowledge and attention to technique reduce the likelihood for majorcomplicationsiques.

EVALUATING EVIDENCE• Major complications associated with the

administration of regional anesthesia areextremely rare even

. Major complications associated with the administration of regional anesthesia are extrThe National Halothane Study is a historical example of vindication of thesafety of halothane based on observational data.2The recall of 28-gauge small-borecatheters (CoSpan, Kendall Healthcare, Mansfield, MA; May 14, 1992) resulted following reports of only seven cases of cauda equina syndrome.emely rare eventsts

FAILURE TO ACHIEVE SURGICAL ANAESTHESIA

• In 1987, Goldberg et al.4compared three methods of axillary block performed by first- and second-year residents.

• Successful surgical anesthesia resulting from transarterial, single paresthesia, and nervestimulation techniques were 79%, 80%, and 70%, respectfully. Contemporary reports indicate that significant improvements in success can be achieved.

. Fanelli et al.5reported a 93% success rate using a multiple nerve stimulation technique.

Informed Consent and Regional Anesthesia

• COMPLICATIONS AND CONTROVERSIES IN REGIONAL ANESTHESIA 47TABLE 1. Controversial Features of Informed Consent for Regional Anesthesia1. Patient refuses to permit resident participation in the performance of RA.2. RA may not be adequate for the operation (failed or partial block).3. The anticipated duration or extent of blockade does not meet the patient or surgeon’sexpectation.4. Discharge plan is impacted by a side effect associated with RA.5. An unanticipated serious complication attributed to RA results during or following

. Disclosure of potential problems (complications) remains an important duty foranesthesiologists.

RISK OF MAJOR COMPLICATIONS• TABLE 2. Morbidity Estimated From Auroy et al.8• and Giayfre et al.9• Peripheral IV • Spinal Epidural Block Regional• Patient population Peds9• Adult8• Peds9• Adult8• Peds9• Adult8• Peds9• Adult8• No. of Procedures 0.5 40.6 17 30.4 9 21.3 >0 11.2• × 1000• Accidental dural — — 4 ? — — 0 —• puncture• Accidental total spinal 0 0 4 ? — — 0 —• Local anesthetic — — 2 4 0 16 0 3• toxicity• Cardiac arrest 0 26 0 3 0 3 0 0• Death 0 6 0 0 0 1 0 0• Neurologic injury/ 0 24/5 2/0 24/1 0 4/0 0

Controversy: Nerve Injury, Paresthesia, and Needles

• Elicitation of a paresthesia may indicate that the point of the needle is in close contact with a nerve or it may serve as a warning indicating that the perineurium has been breached.12

• Acute pain on injection should serve as a warning for repositioning. There is a growing consensus that

neuronal injury is often associated with pain on injection .Since 1977, short-beveled needles have been preferred for peripheral nerve blocks based on the concept that they are less likely to penetrate and injure nerves

COMPLICATIONS COMPILATIONS• COMPLICATIONS AND CONTROVERSIES IN REGIONAL

ANESTHESIA 49• TABLE 3. Historical Complications Reported Following

Epidural/Caudal Blocks17• Epidural (%) Caudal (%)1 Accidental dural puncture 2.5 1.22 Accidental total spinal anesthesia 0.2 0.13 Local anesthetic toxicity 0.2 0.24 Severe hypotension 1.8 0.15 Transient paralysis 0.1 0.026 Permanent paralysis 0.02 0.005

Intravascular Local Anesthetic Toxicity• Unintentional vascular uptake of local anesthetics continues to be a concern.

The prototypical reaction is characterized by central nervous system excitation progressing to cardiovascular collapse.

. the potential for ventricular tachycardia or ventricular fibrillation, and/or cardiac arrest following volume-dependent regionalanesthesia is well recognized.

. seizures occur more often than cardiac toxic0.005S(−) enantiomer of bupivacaine is less toxic than the R(+).

: facilitation of electrical defibrillation, prevention of recurrence of ventricular arrhythmias, enhancement of excitability and conduction of nodal tissue, and normalization of metabolic derangement. New guidelines Use Of Amiodrone.

. There is abundant evidence supporting the potential for enhanced safety by substituting levobupivacaine or ropivacaine for racemic bupivacaine.3

COMPILATION OF COMPLICATIONS• 3 In 1972, Alberg demonstrated that the• COMPLICATIONS AND CONTROVERSIES IN REGIONAL ANESTHESIA

49• TABLE 3. Historical Complications Reported Following

Epidural/Caudal Blocks17• Epidural (%) Caudal (%)• Accidental dural puncture 2.5 1.2• Accidental total spinal anesthesia 0.2 0.1• Local anesthetic toxicity 0.2 0.2• Severe hypotension 1.8 0.1• Transient paralysis 0.1 0.02• Permanent paralysis 0.02

Controversy: The Risk of Performing Regional Anesthesia in Anesthetized Patient

• Difficult to know in unconscious . For this reason, T wave and heart rate criteria for test dosinganesthetized children hTABLE 4. Complications/Accidents Following RA in ChildrenComplication No.1.Inadvertent dural puncture 8

2 Intravascular injections 83 Total spinal blocks 44 CNS toxicity (seizures) 26 Arrhythmia 27 Postoperative paresthesia 18 Rectal puncture 1ave been recommended.

Hemorrhagic Complications of Regional Anesthesia

• Therapeutic hemostatic defects can influence the advisability of performing neuraxial blockade. The risk of hematoma in the absence of bleeding disorders is estimated to be 1 in 150,000 for epidural blockade and 1 in 220,000 for subarachnoid

• injections. The risk of hematoma due to needle or catheter trauma encroaches on the

• 52 GILBERTincidence of spontaneous hematomas in the standard normal population. For this reason, anticoagulation is known to be a dependent variable for developing spinal hematomas. . Before 1994, reports of spontaneous hematomas (many in anticoagulated

• patients undergoing diagnostic spinal taps) were more numerous than those associated with regional anesthesia.

• Aspirin (ASA) and Nonsteroidal Anti-inflammatory Drugs (NSAIDs) Antiplatelet Agents, Neuraxial Blockade and Heparin,Preoperative LMWH, Postoperative LMWH,Unfractionated Heparin (UH), Warfarin,Thrombolytic Agents,Venous Thromboembolism Prevention and Regional Anesthesia

Spinal Local Anesthetic Toxicity• Retrospective reviews and prospective reports estimate the incidence of postoperative neurologic

injury following spinal anesthesia to be 0% to 0.7%.52Closed-claim insurance data in the United States and abroad indicate that persistent paresthesia, radiculopathy, and cauda equina syndrome following neuraxial anesthesia are very rare.53

• Determining the factors that may potentially contribute to the development of neuraxial anaesthesia very rare.

• The best strategy for reducing thispotential cause for toxicity is limiting the maximal dose used for spinal anesthesia.

• There is laboratory evidence suggesting that epinephrine increases the neurotoxic potential o. Quickly, evidence for the potential of sacral pooling as a major risk factor for neurotoxicity developed.

• Documentation of transient (reversible) lumbosacral radiculopathy (TNS) following single needle injections required a closer scrutiny of the applicability of spinal lidocaine, particularly in outpatients. Transient postoperative pain or dysesthesias in the buttocks, thighs, or lower limbs were found to be a common problem associated with spinal lidocaine. Whereas the clinical importance of TNS is obvious, its etiology is still uncertain. Pf intrathecally administered lidocaine.54The potential for TNS and the fear of permanent neurotoxicity has significantly reduced the popularity of spinal lidocaine and the search for safer and better alternatives continues

Neuraxial Regional Anesthetics• spinal anesthesia has been popular in outpatients because of its ease of administration, rapid onset, and

documented reliability. Reports of a 15% to 20% incidence of TNSfollowing arthroscopic, urologic, and gynecologic procedures prompted investigationof practical regional anesthesia alternatives to spinal lidocaine. Replacement possibilities include the following: spinal lidocaine alternatives, substitution with a short-actingepidural technique, and substitution with plexus and or peripheral nerve blocks.

• All neuraxial techniques are associated with the potential risk of headache, hypotension, bradycardia, and postoperative urinary retention. Each of these circumstancesmay potentially delay discharge. Substituting spinal bupivacaine for spinal lidocainereduces the incidence for TNS but may increase discharge times due to the extendedduration of bupivacaine. Lidocaine and bupivacaine spinals produce dose-dependentdisturbances of bladder function. Finding a spinal, spinal-epidural, or epidural technique that matches discharge times followRegression to the third sacral segment is necessary for the complete return of themicturition reflex following spinal anesthesia in men.72 Lowering the dose of spinallocal anesthetic theoretically provides a shorter duration and reduces the potential fordeveloping neurotoxicity. Many anesthesiologists continue to use hyperbaric lidocainelimiting the total instilled dose to 50–60 mg. Others favor substitution with spinal bupivacaine. The addition of 10 µg of intrathecal fentanyl permits reducing the dose of bupivacaine to 5 mg for routine outpatient knee arthroscopy.73Studies of discharge times indicate that it is difficult for spinal or epidural blocks tomatch the speed of recovery associated with modern general anesthesia. Mulroy et al.74compared general, epidural, and spinal for outpatient knee arthroscopy using techniques they thought represented the best case alternatives. Discharge times werelonger in the spinal procaine-fentanyl group, their choice for outpatient spinal. Eing contemporary general anesthesia or local.

Peripheral Regional Anesthetic Blocks and Outpatient Anesthesia

• Need to learn new skills;• Delay associated with development of surgical anesthesia;• Potential for inadequate surgical anesthesia;• Potential for the need of rescue anesthesia;• Potential for local anesthetic toxicity;• Potential for prolonged recovery due to motor block;• Potential for prolonged anesthesia-associated neurologic deficit;• Need for prolonged outpatient surveillance to follow persistent neurologic

deficits/• injuries.• Using peripheral nerve block in outpatients may reduce the incidence of

postPOINT OF DISCUSSION Here

Peripheral Regional Anesthetic Blocks and Outpatient Anesthesia

Performing Peripheral Nerve Block• Peripheral nerve block may fail to meet the expectations of surgeons, patients, and

anesthesiologists. Although paresthesias are undesirable during neuraxial block, many clinicians continue to deliberately elicit paresthesias to identify proximity to neural targets. The association of paresthesia and the potential for a needle induced nerve injury. GILBERT remains controversial. Motorevoked responses reduce the potential failure rate and improve confidence. It is unknown if using motor evoked responses reduces the occurrence of serious complications.

. Ultrasonographic methods of identifying anatomic structures and needle locationhave been applied to the performance of peripheral nerve block.

. Substitution of peripheral nerve block for neuraxial techniques or even generalanesthesia has merit in many clinical situations. The superiority of peripheral nerve block to other contemporary anesthetic or analgesic alternatives will require randomized trial. Fanelli et al.5 found a 1.7% incidence of pain or dysesthesias following anesthesia care. This study was undertaken to investigate failure rate, patient acceptance, and complications following a multiple-injection, nerve stimulation technique. There were no permanent neurologic injuries attributed to peripheral nerve block. Failure rates were <8%. Transient neurologic dysfunction was identified in only seven patients. Symptoms resolved by 2.5 months. Exit surveys indicated that discomfort during peripheral nerve block is asignificant barrier for patient acceptance. Sedation during the initiation of regionalanesthesia is an important component for patient comfort.

CONCLUSION-1.1 Exit surveys indicated that discomfort during

peripheral nerve block is a significant barrier for patient acceptance. S

.2 Sedation during the initiation of regional anesthesia is an important component.

.3 Today, interest in regional anesthesia and in particular peripheral nerve block has increased.surgeons and patients accept the inconvenience associated with performing peripheral nerve block to accrue the potential benefit of an early discharge and improved comfort..

CONCLUSION-24 Observational data indicate that local

anesthetic toxicity and the potential for postoperative neurologic dysfunction following regional anesthesia are rare and often unpredictable.

5 Anesthesiologists must develop strategies to improve their confidence and success rates.

6 Methods for evaluating complications occurring outside of the hospital need to be developed for patient comfort.