Julia E. Pollock

Prospective study of the incidence of transient radicular irritation in patients undergoing spinal anesthesia.

Background There is considerable controversy regarding the role of subarachnoid 5% hyperbaric lidocaine in the syndrome transient radicular irritation (TRI). This randomized, double‐blinded, prospective study was designed to determine the incidence of TRI and identify factors possibly contributing to its development. Methods One hundred fifty‐nine ASA physical status 1 or 2 patients undergoing outpatient knee arthroscopy or unilateral inguinal hernia repair were prospectively randomized to receive spinal anesthesia with 5% hyperbaric lidocaine with epinephrine (60 mg with 0.2 mg epinephrine for arthroscopy or 75 mg with 0.2 mg epinephrine for hernia repair), 2% isobaric lidocaine without epinephrine (60 mg for arthroscopy or 75 mg for hernia repair), or 0.75% hyperbaric bupivacaine without epinephrine (7.5 mg for arthroscopy or 9.0 mg for hernia repair) in a double‐blinded fashion. On the 3rd postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications including TRI, defined as back pain with radiation down one or both buttocks or legs occurring within 24 h after surgery. Postoperatively, time from injection to block resolution, ambulation, voiding, and ready for discharge were recorded by a postanesthesia care unit nurse blinded to the group assignment. Results The incidence of TRI was greater in patients receiving lidocaine than in those receiving bupivacaine (16% vs. 0%; P = 0.003). There was no difference in the incidence of TRI between the patients receiving 59% hyperbaric lidocaine with epinephrine and those receiving 2% isobaric lidocaine without epinephrine (16% vs. 16%; P = 0.98). The incidence of TRI was greater in patients undergoing arthroscopy than in those undergoing hernia repair (13% vs. 5%; P = 0.04). There was no difference in discharge times in patients receiving bupivacaine versus those receiving hyperbaric lidocaine with epinephrine (292 vs. 322 min; P = 0.61). Conclusions The incidence of TRI is greater with lidocaine than bupivacaine, decreasing the lidocaine concentration to 2% does not prevent TRI, and surgical position may be an important contributing factor. Discharge times at our institution are not different when equipotent doses of 0.75% hyperbaric bupivacaine or 5% hyperbaric lidocaine with 0.2 mg epinephrine are used in ambulatory patients undergoing spinal anesthesia.

Dose-response characteristics of spinal bupivacaine in volunteers : Clinical implications for ambulatory anesthesia

Background Small doses of bupivacaine may be a reasonable choice for spinal anesthesia for patients having ambulatory surgery. However, few dose‐response data are available to guide the selection of reasonable doses of bupivacaine for different ambulatory procedures. Methods Eight volunteers per group were randomized to receive 3.75, 7.5, or 11.25 mg of 0.75% bupivacaine with 8.25% dextrose in a double‐blind manner. Sensory block was assessed with pinprick, transcutaneous electrical stimulation equivalent to surgical incision at the ankle, knee, pubis, and umbilicus, and with duration of tolerance to pneumatic thigh tourniquet. Motor block at the quadriceps and gastrocnemius muscles was assessed with isometric force dynamometry. Times until recovery from spinal anesthesia were recorded. Dose‐response relationships were determined by linear regressions. Mean (95% confidence intervals) for durations of sensory and motor block per milligram of bupivacaine administered were calculated from linear regressions. Results Significant dose‐response relationships (P < 0.006) were determined for sensory block, motor block, and time until recovery (R from 0.6 to 0.9). Within the range of doses studied, each additional milligram of bupivacaine was associated with an increase in duration of tolerance to transcutaneous electrical stimulation of 10 (7 to 13) min, an increase in tolerance to tourniquet of 7 (2 to 11) min, an increase in duration of motor block of 8 (5 to 12) min, and an increase in time until recovery of 21 (17 to 25) min. Conclusions These dose‐response data may guide the selection of reasonable doses of bupivacaine for various outpatient procedures, although individual responses vary.

Fentanyl Prolongs Lidocaine Spinal Anesthesia Without Prolonging Recovery

Lidocaine spinal anesthesia is a popular anesthetic for short procedures due to its brief duration.The addition of fentanyl may improve the quality and duration of lidocaine spinal anesthesia. Eight volunteers received plain lidocaine 5% in dextrose (50 mg) both with and without 20 micro gram of fentanyl in a randomized, double-blind, cross-over fashion. Sensory analgesia was assessed with pinprick, cold, touch, transcutaneous electrical stimulation equivalent to surgical incision, and duration of tolerance of pneumatic thigh tourniquet. Motor block was assessed with isometric force dynamometry. Regression of pinprick, touch, and cold was prolonged with fentanyl. Duration of tolerance of electrical stimulation at the umbilicus, hip, knee, and ankle was increased with fentanyl (181% increase from plain lidocaine on average; P < 0.01). Duration of tolerance of tourniquet-induced pain was increased by an average of 48% with addition of fentanyl (P = 0.02). Neither motor block nor time to void was prolonged with fentanyl. Pruritus occurred in all subjects receiving fentanyl but was treated easily and were well tolerated. We recommend the addition of 20 micro gram of fentanyl to lidocaine spinal anesthesia as a means to improve duration of sensory anesthesia without prolonging recovery of motor function or time to micturition. (Anesth Analg 1995;80:730-4)

Sedation during Spinal anesthesia

BACKGROUND Central neuraxial anesthesia has been reported to decrease the dose of both intravenous and inhalational anesthetics needed to reach a defined level of sedation. The mechanism behind this phenomenon is speculated to be decreased afferent stimulation of the reticular activating system. The authors performed a two-part study (nonrandomized pilot study and a subsequent randomized, double-blind, placebo-controlled study) using the Bispectral Index (BIS) monitor to quantify the degree of sedation in unmedicated volunteers undergoing spinal anesthesia. METHODS Twelve volunteers underwent BIS monitoring and observer sedation scoring (Observers Assessment of Alertness/Sedation Scale [OAA/S]) before and after spinal anesthesia with 50 mg hyperbaric lidocaine, 5%. Subsequently, 16 volunteers blinded to the study were randomized to receive spinal anesthesia with 50 mg hyperbaric lidocaine, 5% (n = 10) or placebo (n = 6) and underwent BIS and OAA/S monitoring. RESULTS In part I, significant changes in BIS scores of the volunteers occurred progressively (P = 0.003). The greatest variations from baseline BIS measurement occurred at 30 and 70 min. In part II, there were significant decreases in OAA/S and self-sedation scores for patients receiving spinal anesthesia versuscontrol patients (P = 0.04 and 0. 01, respectively). The greatest decrease in OAA/S scores occurred at 60 min. BIS scores were similar between groups (P = 0.4). CONCLUSIONS Spinal anesthesia is accompanied by significant sedation progressively when compared with controls as measured by OAA/S and self-sedation scores. This effect was not related to block height. The late sedation observed by OAA/S at 60 min may indicate a second mechanism of sedation, such as delayed rostral spread of local anesthetics. BIS was not a sensitive measure of the sedation associated with spinal anesthesia in the randomized, blinded portion of this study.

dilution of Spinal Lidocaine Does Not Alter the Incidence of Transient Neurologic Symptoms

BACKGROUND Although it has been suggested that the dilution of 5% hyperbaric lidocaine before injection for spinal anesthesia may decrease the incidence of transient neurologic symptoms, previous studies have not noted a decreased incidence between 5% and 2% lidocaine. The aim of the current study was to determine whether the incidence of transient neurologic symptoms could be altered by further diluting spinal lidocaine from 2.0% to 0.5%. METHODS One hundred nine patients with American Society of Anesthesiologists physical status 1 or 2 undergoing outpatient knee arthroscopy were randomized in a double-blind fashion to receive 50 mg hyperbaric spinal lidocaine as a 2.0%, 1.0%, or 0.5% concentration. On the third postoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications, including transient neurologic symptoms, defined as pain or dysthesia in one or both buttocks or legs occurring within 24 h of surgery. RESULTS The incidence of transient neurologic symptoms did not differ among patients receiving 2.0% (incidence of 15.8%), 1.0% (incidence of 22.2%), and 0.5% (incidence of 17.1%) lidocaine (P = 0.756). CONCLUSIONS For ambulatory patients undergoing arthroscopy, the incidence of transient neurologic symptoms is not reduced by decreasing spinal lidocaine concentrations from 2.0% to 1.0% or 0.5%. The incidences of transient neurologic symptoms with the 0.5%, 1.0%, and 2.0% solutions are similar to previously reported incidences for 5.0% lidocaine, suggesting that dilution of lidocaine from 5.0% to 0.5% does not change the incidence of these symptoms.

A comparison of spinal, epidural, and general anesthesia for outpatient knee arthroscopy.

We compared general, epidural, and spinal anesthesia for outpatient knee arthroscopy (excluding anterior cruciate ligament repairs). Forty-eight patients (ASA physical status I–III) were randomized to receive either propofol-nitrous oxide general anesthesia with a laryngeal mask airway with anesthetic depth titrated to a bispectral index level of 40–60, 15–20 mL of 3% 2-chloroprocaine epidural, or 75 mg of subarachnoid procaine with 20 &mgr;g fentanyl. All patients were premedicated with <0.035 mg/kg midazolam and <1 &mgr;g/kg fentanyl and received intraarticular bupivacaine and 15–30 mg of IV ketorolac during the procedure. Recovery times, operating room turnover times, and patient satisfaction were recorded by an observer using an objective scale for recovery assessment and a verbal rating scale for satisfaction. Statistical analysis was performed with analysis of variance and &khgr;2. Postanesthesia care unit discharge times for the general and epidural groups were similar (general = 104 ± 31 min, epidural = 92 ± 18 min), whereas the spinal group had a longer recovery time (146 ± 52 min) (P = 0.0003). Patient satisfaction was equally good in all three groups (P = 0.34). Room turnover times did not differ among groups (P = 0.16). There were no anesthetic failures or serious adverse events in any group. Pruritus was more frequent in the spinal group (7 of 16 required treatment) than in the general or epidural groups (no pruritus) (P < 0.001). We conclude that epidural anesthesia with 2-chloroprocaine provides comparable recovery and discharge times to general anesthesia provided with propofol and nitrous oxide. Spinal anesthesia with procaine and fentanyl is an effective alternative and is associated with a longer discharge time and increased side effects. Implications For outpatient knee arthroscopy, anesthesia can be provided adequately with regional or general anesthesia. Epidural and general anesthesia provide equal recovery times and patient satisfaction, whereas spinal anesthesia may prolong recovery and have increased side effects. The choice of anesthesia may depend primarily on the patient’s interest in being alert or asleep during the procedure.

Practice guidelines for the prevention, detection, and management of respiratory depression associated with neuraxial opioid administration.

PRACTICE guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints, and are not intended to replace local institutional policies. In addition, practice guidelines developed by the American Society of Anesthesiologists (ASA) are not intended as standards or absolute requirements, and their use cannot guarantee any specific outcome. Practice guidelines are subject to revision as warranted by the evolution of medical knowledge, technology, and practice. They provide basic recommendations that are supported by a synthesis and analysis of the current literature, expert and practitioner opinion, open forum commentary, and clinical feasibility data. This document updates the “Practice Guidelines for the Prevention, Detection and Management of Respiratory Depression Associated with Neuraxial Opioid Administration” adopted by ASA in 2007, and includes new survey data and recommendations pertaining to monitoring for respiratory depression. Methodology

Transient neurologic symptoms : etiology, risk factors, and management

S ince its introduction in 1948, manufacturers report 5% hyperbaric lidocaine has been used for millions of spinal anesthetics. A predictable onset and limited duration of action have made lidocaine one of the most popular spinal anesthetics. Concern about the use of spinal lidocaine began in 1991 with published reports of cauda equina syndrome (CES) after continuous spinal anesthesia1,2 and was heightened in 1993 when Schneider et al.3 published a case report of 4 patients undergoing spinal anesthesia who postoperatively experienced aching and pain in the buttocks and lower extremities. This report will review the history, incidence, possible etiologies, risk factors, and treatment of transient neurologic symptoms (TNS) after lidocaine spinal anesthesia.

Practice advisory for the prevention, diagnosis, and management of infectious complications associated with neuraxial techniques: A report by the american society of anesthesiologists task force on infectious complications associated with neuraxial techniques

P RACTICE advisories are systematically developed reports that are intended to assist decision making in areas of patient care. Advisories are based on a synthesis of scientific literature and analysis of expert opinion, clinical feasibility data, open forum commentary, and consensus surveys. Advisories developed by the American Society of Anesthesiologists (ASA) are not intended as standards, guidelines, or absolute requirements. They may be adopted, modified, or rejected according to clinical needs and constraints. The use of practice advisories cannot guarantee any specific outcome. Practice advisories summarize the state of the literature and report opinions obtained from expert consultants and ASA members. Practice advisories are not supported by scientific literature to the same degree as standards or guidelines because of the lack of sufficient numbers of adequately controlled studies. Practice advisories are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice. Methodology

Neurotoxicity of intrathecal local anaesthetics and transient neurological symptoms.

Local anaesthetics have been placed in the intrathecal space for approximately 100 years. Currently used intrathecal local anaesthetics appear to be relatively benign on the basis of the low incidence of permanent neurological deficits. In large retrospective surveys of 4000-10 000 patients, the incidence of persistent neurological sequelae after subarachnoid anaesthesia varies between 0.01 and 0.7%. Since its introduction in 1948, hyperbaric 5% lidocaine has been used for millions of spinal anaesthetics. The predictable onset and limited duration of action have made lidocaine one of the most popular spinal anaesthetics currently available. Concern about the use of spinal lidocaine began in 1991 with published reports of cauda equina syndrome after continuous spinal anaesthesia. In 1993, Schneider published a case report of four patients undergoing spinal anaesthesia who postoperatively experienced aching and pain in the buttocks and lower extremities. This chapter reviews the neurotoxicity of spinal local anaesthetics, as well as the incidence, possible aetiology, and treatment of transient neurological symptoms after lidocaine spinal anaesthesia.