A Three-arm Randomized Clinical Trial Comparing Continuous Femoral Plus Single-injection Sciatic Peripheral Nerve Blocks versus Periarticular Injection with Ropivacaine or Liposomal Bupivacaine for Patients Undergoing Total Knee Arthroplasty.

BACKGROUND: Multimodal analgesia is standard practice for total knee arthroplasty; however, the role of regional techniques in improved perioperative outcomes remains unknown. The authors hypothesized that peripheral nerve blockade would result in lower pain scores and opioid consumption than two competing periarticular injection solutions. METHODS: This three-arm, nonblinded trial randomized 165 adults undergoing unilateral primary total knee arthroplasty to receive (1) femoral catheter plus sciatic nerve blocks, (2) ropivacaine-based periarticular injection, or (3) liposomal bupivacaine-based periarticular injection. Primary outcome was maximal pain during postoperative day 1 (0 to 10, numerical pain rating scale) in intention-to-treat analysis. Additional outcomes included pain scores and opioid consumption for postoperative days 0 to 2 and 3 months. RESULTS: One hundred fifty-seven study patients received peripheral nerve block (n = 50), ropivacaine (n = 55), or liposomal bupivacaine (n = 52) and reported median maximal pain scores on postoperative day 1 of 3, 4, and 4.5 and on postoperative day 0 of 1, 4, and 5, respectively (average pain scores for postoperative day 0: 0.6, 1.7, and 2.4 and postoperative day 1: 2.5, 3.5, and 3.7). Postoperative day 1 median maximal pain scores were significantly lower for peripheral nerve blockade compared to liposomal bupivacaine-based periarticular injection (P = 0.016; Hodges-Lehmann median difference [95% CI] = -1 [-2 to 0]). After postanesthesia care unit discharge, postoperative day 0 median maximal and average pain scores were significantly lower for peripheral nerve block compared to both periarticular injections (ropivacaine: maximal -2 [-3 to -1]; P < 0.001; average -0.8 [-1.3 to -0.2]; P = 0.003; and liposomal bupivacaine: maximal -3 [-4 to -2]; P < 0.001; average -1.4 [-2.0 to -0.8]; P < 0.001). CONCLUSIONS: Ropivacaine-based periarticular injections provide pain control comparable on postoperative days 1 and 2 to a femoral catheter and single-injection sciatic nerve block. This study did not demonstrate an advantage of liposomal bupivacaine over ropivacaine in periarticular injections for total knee arthroplasty.

The Impact of Anesthetic Management on Surgical Site Infections in Patients Undergoing Total Knee or Total Hip Arthroplasty.

BACKGROUND: Surgical site infection (SSI) is one of the most challenging and costly complications associated with total joint arthroplasty. Our primary aim in this case-controlled trial was to compare the risk of SSI within a year of surgery for patients undergoing primary total knee arthroplasty (TKA) or total hip arthroplasty (THA) and revision TKA or THA under general anesthesia versus neuraxial anesthesia. Our secondary aim was to determine which patient, anesthetic, and surgical variables influence the risk of SSI. We hypothesized that patients who undergo neuraxial anesthesia may have a lesser risk of SSI compared with those who had a general anesthetic. METHODS: We conducted a retrospective, case-control study of patients undergoing primary or revision TKA and THA between January 1, 1998, and December 31, 2008, who subsequently were diagnosed with an SSI. The cases were matched 1:2 with controls based on type of joint replacement (TKA versus THA), type of procedure (primary, bilateral, revision), sex, date of surgery (within 1 year), ASA physical status (I and II versus III, IV, and V), and operative time (<3 vs >3 hours). RESULTS: During the 11-year period, 202 SSIs were identified. Of the infections identified, 115 (57%) occurred within the first 30 days and 87 (43%) occurred between 31 and 365 days. From both univariate and multivariable analyses, no significant association was found between the use of central neuraxial anesthesia and the postoperative infection (univariate odds ratio [OR] = 0.92; 95% confidence interval [CI], 0.63-1.34; P = 0.651; multivariable OR = 1.10; 95% CI, 0.72-1.69; P = 0.664). The use of peripheral nerve block also was not found to influence the risk of postoperative infection (univariate OR = 1.41; 95% CI, 0.84-2.37; P = 0.193; multivariable OR = 1.35; 95% CI, 0.75-2.44; P = 0.312). The factors that were found to be associated with postoperative infection in multivariable analysis included current smoking (OR = 5.10; 95% CI, 2.30-11.33) and higher body mass index (BMI) (OR = 2.68; 95% CI, 1.42-5.06 for BMI ≥ 35 kg/m compared with those with BMI < 25 kg/m). CONCLUSIONS: Recent studies using large databases have concluded that the use of neuraxial compared with general anesthesia is associated with a decreased incidence of SSI in patients undergoing total joint arthroplasty. In this retrospective, case-controlled study, we found no difference in the incidence of SSI in patients undergoing total joint arthroplasty under general versus neuraxial anesthesia. We also concluded that the use of peripheral nerve blocks does not influence the incidence of SSI. Increasing BMI and current smoking were found to significantly increase the incidence of SSI in patients undergoing lower extremity total joint arthroplasty.

Factors that influence the selection of sterile glove brand: a randomized controlled trial evaluating the performance and cost of gloves.

PURPOSE: To determine whether glove use modifies tactile and psychomotor performance of health care providers when compared with no glove use and to evaluate factors that influence the selection of sterile glove brand. METHODS: Forty-two anesthesia providers (nine anesthesiologists, seven nurse anesthetists, 20 residents, six student nurse anesthetists) enrolled in and completed this cross-over randomized trial from May 2010 until August 2011. Participants underwent standardized psychomotor testing while wearing five different types of protective gloves. Assessments of psychomotor performance included tactile, fine motor/dexterity, and hand-eye coordination tests. Subjective ratings of glove comfort and performance were reported at the completion of each glove trial. The manufacturer's suggested retail price was collected for each glove tested. RESULTS: There were statistically significant differences in touch sensitivity for all nerve distributions, with all glove types resulting in less sensitivity than a bare hand. When compared with the non-sterile glove, only the thickest glove tested (Ansell Perry Orthopaedic) was found to have less touch sensitivity. Fine motor dexterity testing revealed no statistically significant differences in time to completion amongst glove types or bare handed performance. In hand-eye coordination testing across treatment conditions, the thickest glove tested (Ansell Perry(®) Orthopaedic) was the only glove to show a statistically significant difference from a bare hand. There were statistically significant differences in glove comfort ratings across glove types, with latex-free, powder-free (Cardinal Esteem(®)), and latex powder-free (Mölnlycke-Biogel(®)) rated highest; however, there were no statistically significant differences in subjective performance ratings across glove types. CONCLUSIONS: Given the observed similarities in touch sensitivity and psychomotor performance associated with five different glove types, our results suggest that subjective provider preferences, such as glove comfort, should be balanced against material costs.

Safe and individualized labor analgesia: A review of the current options.

Although some women want to experience childbirth without medications, most women in the United States labor with an epidural or spinal analgesic. Epidurals provide relatively consistent pain relief, are long-lasting, can be titrated according to the analgesic needs of the mother, and can be bolused for procedures such as forceps, vacuum, or cesarean delivery. But they can have undesirable side effects including lower-extremity motor block, hypotension, urinary retention, and pruritus, and they may increase the risk for a slightly prolonged labor, a forceps or vacuum delivery, and fever during labor. This article describes the current thinking regarding labor analgesia and how anesthesiologists and obstetricians can help women have a birth experience that is both safe and satisfying.

Perioperative nerve injury after total knee arthroplasty: regional anesthesia risk during a 20-year cohort study.

BACKGROUND: Perioperative nerve injury (PNI) is one of the most debilitating complications after total knee arthroplasty (TKA). Although regional anesthesia (RA) techniques reduce pain and improve functional outcomes after TKA, they may also contribute to PNI. The objective of this study was to test the hypothesis that PNI risk differs among patients according to RA use during TKA. METHODS: All patients aged at least 18 yr who underwent elective TKA from January 1988 to July 2007 were retrospectively identified. The primary outcome variable was the presence of a new PNI documented within 3 months of the procedural date. Age, sex, body mass index, type of procedure, tourniquet time, type of anesthesia, and use of peripheral nerve blockade were evaluated as potential risk factors for PNI using multivariable logistic regression. RESULTS: Ninety-seven cases of PNI were identified among 12,329 patients. Overall incidence of PNI was 0.79% (95% CI, 0.64-0.96%). PNI was not associated with peripheral nerve blockade (odds ratio [OR], 0.97) or type of anesthesia (OR, 1.10 [neuraxial vs. general]; OR, 1.82 [combined vs. general]). Risk for PNI decreased with age (OR, 0.68 [per decade]; P < 0.001) but increased with tourniquet time (OR, 1.28 [per 30-min increase]; P = 0.003) and bilateral procedures (OR, 2.51; P < 0.001). Patients with PNI who underwent peripheral nerve blockade were less likely to have complete neurologic recovery (OR, 0.37; P = 0.03). CONCLUSIONS: Risk for PNI after TKA was unchanged by the use of RA techniques. This finding supports the notion that the known benefits of RA for patients undergoing TKA can be achieved without increasing risk of neurologic injury. However, in rare situations when PNI occurs, complete recovery may be less likely if it develops after peripheral nerve blockade.

Perioperative nerve injury after total hip arthroplasty: regional anesthesia risk during a 20-year cohort study.

BACKGROUND: Perioperative nerve injury (PNI) is a recognized complication of total hip arthroplasty (THA). Regional anesthesia (RA) techniques may increase the risk of neurologic injury. Using a retrospective cohort study, the authors tested the hypothesis that use of RA increases the risk for PNI after elective THA. METHODS: All adult patients who underwent elective THA at Mayo Clinic during a 20-yr period were included. The primary outcome was the presence of a new PNI within 3 months of surgery. Multivariable logistic regression was used to evaluate patient, surgical, and anesthetic risk factors for PNI. RESULTS: Of 12,998 patients undergoing THA, 93 experienced PNI (incidence = 0.72%; 95% CI 0.58-0.88%). PNI was not associated with type of anesthesia (OR = 0.72 for neuraxial-combined vs. general; 95% CI 0.46-1.14) or peripheral nerve blockade (OR = 0.65; 95% CI 0.34-1.21). The risk for PNI was associated with younger age (OR = 0.79 per 10-yr increase; 95% CI 0.69-0.90), female gender (OR = 1.72; 95% CI 1.12-2.64), longer operations (OR = 1.10 per 30-min increase; 95% CI 1.03-1.18) or posterior surgical approach (OR = 1.91 vs. anterior approach; 95% CI 1.22-2.99). Neurologic recovery was not influenced by the use of RA techniques in patients with PNI. CONCLUSIONS: The risk for PNI after THA was not increased with the use of neuraxial anesthesia or peripheral nerve blockade. Neurologic recovery in patients who experienced PNI was not affected by the use of RA. These results support the use of RA techniques in patients undergoing elective THA given their known functional and clinical benefits.

A case series of the anesthetic management of parturients with surgically repaired tetralogy of Fallot.

BACKGROUND: Most case reports of pregnancies after surgical repair of tetralogy of Fallot have focused on cardiovascular and obstetric concerns, with relatively few authors focusing on specific intrapartum and postpartum anesthetic management strategies. METHODS: The Mayo Clinic Congenital Heart Disease Clinic and the Boston Adult Congenital Heart Disease Service databases were cross-referenced with the Mayo Clinic and the Brigham and Women's Hospital Department of Anesthesiology databases to identify patients with tetralogy of Fallot who delivered at their respective hospital from January 1, 1994, to January 1, 2008. We reviewed each medical record to evaluate parturient care during pregnancy, labor, and delivery with a focus on anesthetic management. RESULTS: During the 14-year study period, a total of 27 deliveries in 20 patients with repaired tetralogy of Fallot were identified. Twenty-one deliveries (78%) among 15 parturients (75%) involved a trial of labor; all parturients received neuraxial analgesia for labor and delivery, including 18 (86%) epidural, 2 (10%) combined spinal-epidural, and 1 (5%) continuous spinal anesthetic after an unintended dural puncture. Of the 21 patients undergoing labor, 3 (14%) received invasive arterial blood pressure monitoring; 5 (24%) received continuous telemetry; 3 (14%) experienced congestive heart failure that required diuresis; 4 (19%) had obstetric or neonatal complications; and 3 (14%) had anesthesia complications. Cesarean delivery was required in 4 patients (19%) because of labor complications. Concurrent cardiovascular, obstetric, and anesthetic complications in 1 patient resulted in neonatal death. Six (22%) parturients underwent elective cesarean delivery; 4 received epidural and 2 received spinal anesthesia; no anesthetic or immediate obstetric complications occurred. Among all parturients, 5 deliveries in 5 separate parturients (19% of deliveries) reported symptoms of congestive heart failure at the time of delivery. CONCLUSIONS: Pregnancy outcomes for patients with repaired tetralogy of Fallot were found to be generally favorable. All patients undergoing a trial of labor or cesarean delivery had neuraxial analgesia or anesthesia. Recognition and management of congestive heart failure was necessary in 19% of deliveries.

Infectious complications of regional anesthesia.

PURPOSE OF REVIEW: Regional anesthesia is commonly used to provide intraoperative anesthesia and postoperative analgesia. Potential complications of both neuraxial and peripheral regional techniques include infectious sequelae. This review examines important components of practice that are known to minimize the risk of infection associated with regional anesthesia. RECENT FINDINGS: Healthcare-associated infections increase morbidity and mortality, patient pain and suffering, direct medical costs, and hospital length-of-stay. Recently published national guidelines from subspecialty societies and government agencies emphasize the importance of strict aseptic technique in the prevention of infectious complications associated with regional anesthesia. Proper hand hygiene, the use of surgical masks, appropriate antiseptic selection and application, and proper preparation of local anesthetic infusate solutions are all considered essential components of asepsis. Anesthesia providers need to adhere to strict aseptic guidelines to minimize the risk of potentially devastating infectious complications. SUMMARY: Infectious complications associated with regional anesthesia are exceedingly rare events. Adherence to strict aseptic guidelines as published by the American Society of Regional Anesthesia and Pain Medicine, American Society of Anesthesiologists, and the Royal College of Anaesthetists may reduce the risk of infectious complications.

Multimodal clinical pathways, perineural catheters, and ultrasound-guided regional anesthesia: the anesthesiologist's repertoire for the 21st century.

Regional anesthesia is making a comeback because of improved technology and research that shows that its use results in less discomfort for patients and shorter hospital stays. This article provides a brief history of regional anesthesia, describes current techniques for administering it, and discusses potential benefits associated with it. It also describes Mayo Clinic's Total Joint Regional Anesthesia Clinical Pathway, a comprehensive care plan for patients undergoing joint replacement surgery that uses peripheral nerve blockade and multimodal analgesia.

Examining Use of Low-Dose Ketamine Infusions During the Postoperative Period: A Retrospective Study Comparing Opioid-Tolerant and Nonopioid-Tolerant Patients.

Ketamine is a well-known anesthetic that has been used since the 1970s. Despite its ubiquitous use as a postoperative analgesic, no studies have described dosing differences between opioid-tolerant (OT) and nonopioid-tolerant (NOT) patients or determined optimal dosing. The primary aim of this study was to assess whether OT and NOT patients had significant differences in ketamine infusion dosing requirements. We also aimed to measure the overall incidence of psychotomimetic adverse effects associated with low-dose ketamine infusions. We hypothesized that NOT patients would have lower ketamine infusion dosing requirements and a higher incidence of psychotomimetic adverse effects compared with OT patients. We performed a retrospective chart review and showed that the percentages of OT and NOT patients experiencing psychotomimetic adverse effects were similar (15.5% vs 15.3%; P=.93) and that increasing age was the only factor associated with increased odds of experiencing a psychotomimetic adverse effect potentially associated with ketamine (odds ratio, 1.29 [95% CI, 1.11-1.50]; P=.001). Optimal subanesthetic ketamine infusion dosing could not be established, and further research in this area may be warranted.

Neuraxial blockade in patients with preexisting spinal stenosis, lumbar disk disease, or prior spine surgery: efficacy and neurologic complications.

BACKGROUND: Patients with spinal canal pathology, including spinal stenosis and lumbar disk disease, are often not considered candidates for neuraxial blockade because of the risk of exacerbating preexisting neurologic deficits or developing new neurologic dysfunction. In contrast, a history of spine surgery is thought to increase the likelihood of difficult or unsuccessful block. In this retrospective study we investigated the risk of neurologic complications and block efficacy in patients with preexisting spinal canal pathology, with or without a history of spine surgery, after neuraxial anesthesia. METHODS: During the 15-year study period, all patients with a history of spinal stenosis or lumbar radiculopathy undergoing a neuraxial technique were studied. Patient demographics, preoperative neurologic diagnoses and neurologic findings at the time of surgery/neuraxial block, details of the neuraxial block including technique (spinal vs. epidural, single injection vs. continuous), injectate, technical complications (paresthesia elicitation, bloody needle/catheter placement, inability to advance catheter, accidental dural puncture), and block success were noted. New or progressive neurologic deficits were identified. All patients were followed until resolution or last date of evaluation. RESULTS: There were 937 patients included, 207 (22%) of whom had undergone spinal surgery. A history of spinal stenosis was present in 187 (20%), lumbar radiculopathy in 570 (61%), and peripheral neuropathy in 210 (22%) patients; 180 patients (19%) had multiple neurologic diagnoses. A majority of patients had active but stable neurologic symptoms at the time of surgery. Overall block success was 97.2%. A history of spine surgery did not affect the success rate or frequency of technical complications. Ten (1.1%; 95% confidence interval [CI] 0.5%-2.0%) patients experienced new deficits or worsening of existing symptoms. Three (1.4%) complications occurred in patients with a history of spinal surgery, and the remaining 7 (1.0%) in patients without prior surgical decompression or stabilization (P = NS). Although an orthopedic procedure was not a risk factor, in 5 of the 6 patients in which the surgery was a unilateral lower extremity procedure, the postoperative deficit involved the operative side. Likewise, in both patients undergoing bilateral orthopedic procedures who developed bilateral deficits, the outcome was worse on the previously affected side. A surgical cause was presumed to be the primary etiology in 4 (40%) of 10 patients. The primary etiology of the remaining 6 (60%) complications was judged to be nonsurgical (including anesthetic-related factors). The presence of a preoperative diagnosis of compressive radiculopathy (P = 0.0495) or multiple neurologic diagnoses (P = 0.005) increased the risk of neurologic complications postoperatively. CONCLUSIONS: We conclude that patients with preexisting spinal canal pathology have a higher incidence of neurologic complications after neuraxial blockade (1.1%; 95% CI 0.5%-2.0%) than that previously reported for patients without such underlying pathology. However, in the absence of a control group of surgical patients with similar anatomic pathology undergoing general anesthesia, we cannot determine whether the higher incidence of neurologic injury is secondary to the surgical procedure, the anesthetic technique, the natural history of spinal pathology, or a combination of factors and the relative contributions of each.

Contemporary pain management strategies for minimally invasive total knee arthroplasty.

The introduction of minimally invasive total knee arthroplasty has been accompanied by substantial changes in anesthesia and analgesia techniques. It is well recognized that the goals of minimally invasive surgery, which include rapid rehabilitation and improved patient function, cannot be achieved without excellent postoperative analgesia. Traditional postoperative pain management has been associated with high rates of suboptimal pain control, however. The conventional options for early postsurgical pain management include indwelling epidural catheters, which require changes in postoperative prophylaxis for thromboembolism, and patient-controlled analgesia pumps, which are associated with fluctuating pain levels and inconsistent pain relief. Numerous adverse effects are associated with traditional opioid medications, including respiratory depression, urinary retention, nausea, sedation, constipation, and pruritus. Safe, effective, and well-tolerated early pain relief after a minimally invasive knee replacement can be accomplished using a multimodal oral pain regimen, peripheral nerve blocks, and local injections.

Regional blockade in patients with a history of a seizure disorder.

BACKGROUND: Systemic local anesthetic toxicity is a potential complication in patients undergoing regional anesthesia, particularly during procedures requiring large doses of local anesthetic, such as epidurals, caudals, and peripheral nerve blocks. It is unknown whether patients with a history of a seizure disorder are at an increased risk of central nervous system toxicity (seizures) after local anesthetic administration. METHODS: We retrospectively reviewed the medical records of all patients with documented history of a seizure disorder who underwent epidural, caudal, or peripheral nerve block from January 1, 1988 to December 31, 2001. Patient demographics, character of the seizure disorder, details of the regional procedure, and seizure activity in the perioperative period were recorded. The rate of seizure due to local anesthetic toxicity per 10,000 anesthetics was estimated using a point estimate and corresponding 95% confidence interval (CI). RESULTS: During the 14-yr study period, 411 procedures in 335 patients with a seizure disorder were identified. Twenty-four patients experienced postoperative seizure activity. The timing of the most recent (preoperative) seizure was found to be significantly related to the likelihood of experiencing a postoperative seizure (P < 0.001). Based on the extended time interval between local anesthetic injection and/or termination of the infusion and the event, it was determined that the regional anesthetic was neither the primary etiology nor a contributing factor for the seizure in 19 of the 24 patients. In the remaining five patients, perioperative seizure activity was characteristic of their usual seizures. Although unlikely to be the cause of the seizure, local anesthetic toxicity could not be absolutely excluded as a contributing factor to the event in these five patients. Assuming that none of the seizures was related to local anesthetic toxicity the estimated incidence is 0 per 10,000 (95% CI 0-89 per 10,000). Conversely, if the seizures were related to local anesthetic toxicity in the five cases, the incidence is increased to 120 per 10,000 (95% CI 40-280 per 10,000). CONCLUSIONS: We conclude that majority of seizures occurring in the perioperative period in patients with a preexisting seizure disorder are likely related to the patient's underlying condition and that regional anesthesia in these patients is not contraindicated. Furthermore, because the likelihood of a postoperative seizure is increased in patients with a recent seizure, it is essential to be prepared to treat seizure activity, regardless of the anesthetic and analgesic technique.

Clinical utility of low-volume ultrasound-guided interscalene blockade: contraindications reconsidered.

OBJECTIVE: The purpose of this series is to describe cases in which ultrasound guidance was used to allow patients to receive the benefits of regional anesthesia while safely circumventing traditional contraindications to interscalene blockade (ISB). METHODS: Targeted low-volume ISB was performed in 3 patients in whom this procedure would typically be contraindicated because of phrenic nerve blockade or risk of local anesthetic toxicity. A patient with severe respiratory dysfunction, a patient undergoing bilateral shoulder surgery, and a patient requiring awake fiberoptic intubation underwent low-volume ultrasound-guided ISB. The ultrasound technique involved the use a low local anesthetic volume, anatomic identification of the brachial plexus trunk, needle placement opposite the phrenic nerve position, and control over local anesthetic spread. RESULTS: In both patients in whom diaphragmatic paralysis was a concern, postoperative respiratory parameters indicated successful regional analgesia without evidence of phrenic nerve blockade. In the patient requiring an additional regional anesthetic procedure, ISB was performed with a local anesthetic volume low enough to avoid exceeding toxic safety thresholds. CONCLUSIONS: Although further studies are warranted, we report on 3 cases in which ultrasound guidance was used to allow patients to receive the benefits of regional anesthesia while safely avoiding standard contraindications to ISB. Ultrasound technology may allow providers to perform low-volume brachial plexus blockade while avoiding issues related to phrenic nerve blockade and systemic local anesthetic toxicity.

Status epilepticus and intrathecal fluorescein: anesthesia providers beware.

Fluorescein is a fluorochrome dye occasionally administered by intrathecal injection to identify and localize cerebrospinal fluid leaks. Although generally considered to be a benign intervention, intrathecal administration of fluorescein has resulted in adverse events. We report a case of status epilepticus after intrathecal administration of fluorescein. Anesthesia providers should be aware of complications associated with intrathecal fluorescein use and be prepared to manage neurologic complications during the perioperative period.

Anesthetic management of parturients with congenitally corrected transposition of the great arteries: three cases and a review of the literature.

Women with congenitally corrected transposition of the great arteries (CCTGA) have a propensity for congestive heart failure and cardiac dysrhythmias during pregnancy, labor, and delivery. We report the successful obstetric and anesthetic management of three women with CCTGA, review the pertinent medical literature, and discuss important issues surrounding the anesthetic management of parturients with CCTGA.

Minimally invasive retrieval of knotted nonstimulating peripheral nerve catheters.

OBJECTIVE: Continuous peripheral nerve blockade is rapidly becoming the technique of choice for the management of postoperative orthopedic pain. However, the insertion of perineural catheters may be associated with complications, including catheter kinking and knotting. A knotted catheter may be difficult or impossible to remove at the patient bedside, requiring surgical excision under general anesthesia. We describe a previously unreported minimally invasive technique of retrieving knotted peripheral nerve catheters and avoiding the need for surgical intervention. Although the described technique has been used by interventional radiologists for the removal of knotted intravascular devices, it has not been previously described for the retrieval of knotted perineural catheters. BRIEF REPORT: The Mayo Clinic Acute Pain Service database was queried and patients identified with knotted peripheral nerve catheters during the 3-year period from January 2003 to January 2006. The medical records of all identified patients were retrospectively reviewed and details of catheter placement including catheter type and location, size (gauge), ease of placement, distance threaded, and duration of use recorded. During the study period, 5,964 nonstimulating peripheral nerve catheters were placed. Of these, 8 (0.13%) patients experienced catheter knotting resulting in difficult or impossible catheter removal at the bedside. Seven (88%) of the 8 catheters were successfully removed by using a minimally invasive technique of catheter retrieval using guided fluoroscopy. The remaining catheter was removed at the bedside with patient repositioning. CONCLUSIONS: The knotting of peripheral nerve catheters is a relatively uncommon phenomenon, occurring in only 0.13% of patients. However, because the use of perineural catheters has increased within anesthesia practice, clinicians may begin to encounter these complications with greater frequency. Practitioners should be aware of surgical alternatives, including guided-fluoroscopic techniques, when simple catheter traction or tension proves unsuccessful at the patient bedside.

Neuraxial anesthesia and analgesia in patients with preexisting central nervous system disorders.

Historically, the use of regional anesthetic techniques in patients with preexisting central nervous system (CNS) disorders has been considered relatively contraindicated. The fear of worsening neurologic outcome secondary to mechanical trauma, local anesthetic toxicity, or neural ischemia is commonly reported. We examined the frequency of new or progressive neurologic complications in patients with preexisting CNS disorders who subsequently underwent neuraxial blockade. The medical records of all patients at the Mayo Clinic from the period 1988 to 2000 with a history of a CNS disorder who subsequently received neuraxial anesthesia or analgesia were retrospectively reviewed. One-hundred-thirty-nine (n = 139) patients were identified for study inclusion. Mean patient age was 60 +/- 17 yr. Gender distribution was 86 (62%) males and 53 (38%) females. An established CNS disorder diagnosis was present a mean of 23 +/- 23 yr at the time of surgical anesthesia, with 74 (53%) patients reporting active neurologic symptoms. Spinal anesthesia was performed in 75 (54%) patients, epidural anesthesia or analgesia in 58 (42%) patients, continuous spinal anesthesia in 4 (3%) patients, and a combined spinal-epidural technique in 2 (1%) patients. Bupivacaine was the local anesthetic most commonly used in all techniques. Epinephrine was added to the injectate in 72 (52%) patients. There were 15 (11%) technical complications, with the unintentional elicitation of a paresthesia and traumatic needle placement occurring most frequently. A satisfactory block was reported in 136 (98%) patients. No new or worsening postoperative neurologic deficits occurred when compared to preoperative findings (0.0%; 95% confidence interval, 0.0%-0.3%). We conclude that the risks commonly associated with neuraxial anesthesia and analgesia in patients with preexisting CNS disorders may not be as frequent as once thought and that neuraxial blockade should not be considered an absolute contraindication within this patient population.

Neurologic complications after neuraxial anesthesia or analgesia in patients with preexisting peripheral sensorimotor neuropathy or diabetic polyneuropathy.

BACKGROUND: The risk of severe neurologic injury after neuraxial blockade is extremely rare among the general population. However, patients with preexisting neural compromise may be at increased risk of further neurologic sequelae after neuraxial anesthesia or analgesia. METHODS: We retrospectively investigated 567 patients with a preexisting peripheral sensorimotor neuropathy or diabetic polyneuropathy who subsequently underwent neuraxial anesthesia or analgesia. Patient demographics, neurologic history, the indication and type of neuraxial blockade, complications, and block outcome were collected for each patient. RESULTS: The majority of patients had chronically stable neurologic signs or symptoms at the time of block placement, with very few reporting progression of their symptoms within the last 6 mo. The type of neuraxial technique included spinal anesthesia in 325 (57%) patients, epidural anesthesia or analgesia in 214 (38%) patients, continuous spinal anesthesia in 24 (4%) patients, and a combined spinal-epidural technique in four (1%) patients. Overall, two (0.4%; 95% CI 0.1%-1.3%) patients experienced new or progressive postoperative neurologic deficits, in the setting of an uneventful neuraxial technique. In these patients, the neuraxial block may have contributed to the injury secondary to direct trauma or local anesthetic neurotoxicity around an already vulnerable nerve. Sixty-five (11.5%) technical complications occurred in 63 patients. The most common complication was unintentional elicitation of a paresthesia (7.6%), followed by traumatic (evidence of blood) needle placement (1.6%) and unplanned dural puncture (0.9%). There were no infectious or hematologic complications. CONCLUSIONS: The risk of severe postoperative neurologic dysfunction in patients with peripheral sensorimotor neuropathy or diabetic polyneuropathy undergoing neuraxial anesthesia or analgesia was found to be 0.4% (95% CI 0.1%-1.3%). Clinicians should be aware of this potentially high-risk subgroup of patients when developing and implementing a regional anesthetic care plan.

Anesthetic, patient, and surgical risk factors for neurologic complications after prolonged total tourniquet time during total knee arthroplasty.

Nerve injury after prolonged tourniquet inflation results from the combined effects of ischemia and mechanical trauma. Tourniquet release, allowing a reperfusion interval of 10-30 min followed by re-inflation, has been recommended to extend the duration of total tourniquet time. However, this practice has not been confirmed clinically. We retrospectively reviewed the medical records of 1001 patients undergoing 1166 primary or revision knee replacements with tourniquet time more than 120 min during a 5-yr interval. Mean total tourniquet time was 145 +/- 25 min (range, 120-308 min). In 759 patients, the tourniquet inflation was uninterrupted. Two tourniquet inflations, interrupted by a single deflation, were noted in 371 patients, and 3 tourniquet inflations interrupted by 2 deflation intervals were noted in 23 patients. A total of 129 neurologic complications (peroneal and/or tibial nerve palsies) were noted in 90 patients for an overall incidence of 7.7%. Eighty-five cases involved the peroneal nerve and 44 cases involved the tibial nerve. In 39 cases, both peroneal and tibial deficits were noted. Complete neurologic recovery occurred in 76 (89%) peroneal and 44 (100%) tibial palsies. Postoperative neurologic dysfunction was associated with younger age (P < 0.001; odds ratio = 0.7 per 10-yr increase), longer tourniquet time (P < 0.001; odds ratio = 2.8 per 30-min increase), and preoperative flexion contracture >20 degrees (P = 0.002; odds ratio = 3.9). In a subset of 116 patients with tourniquet times > or =180 min, longer duration of deflation was associated with a decreased frequency of neurologic complications (P = 0.048). We conclude that the likelihood of neurologic dysfunction increases with total tourniquet time and that a reperfusion interval only modestly decreases the risk of nerve injury.