HIV: ageing, cognition and neuroimaging at 4-year follow-up.

OBJECTIVES: The aim of the study was to investigate the hypothesis of accelerated cognitive ageing in HIV-positive individuals using longitudinal assessment of cognitive performance and quantitative magnetic resonance imaging (MRI). METHODS: We assessed a broad cognitive battery and quantitative MRI metrics [voxel-based morphometry (VBM) and diffusion tensor imaging (DTI)] in asymptomatic HIV-positive men who have sex with men (15 aged 20-40 years and 15 aged ≥ 50 years), and HIV-seronegative matched controls (nine aged 20-40 years and 16 aged ≥ 50 years). RESULTS: Being HIV positive was associated with greater decreases in executive function and global cognition. Additionally, using DTI, we found that the HIV-positive group had a greater increase in mean diffusivity, but we did not find group differences in volume change using VBM. With respect to the HIV status by age group interaction, this was statistically significant for change in global cognition, with older HIV-positive individuals showing greater global cognitive decline, but there were no significant interaction effects on other measures. Lastly, change in cognitive performance was correlated with change in the DTI measures, and this effect was stronger for the HIV-positive participants. CONCLUSIONS: In the present study, we found some evidence for accelerated ageing in HIV-positive individuals, with a statistically significant HIV status by age group interaction in global cognition, although this interaction could not be explained by the imaging findings. Moreover, we also found that change in cognitive performance was correlated with change in the DTI measures, and this effect was stronger for the HIV-positive participants. This will need replication in larger studies using a similarly lengthy follow-up period.

Semi-automated International Cartilage Repair Society scoring of equine articular cartilage lesions in optical coherence tomography images.

BACKGROUND: Arthroscopic optical coherence tomography (OCT) is a promising tool for the detailed evaluation of articular cartilage injuries. However, OCT-based articular cartilage scoring still relies on the operator's visual estimation. OBJECTIVES: To test the hypothesis that semi-automated International Cartilage Repair Society (ICRS) scoring of chondral lesions seen in OCT images could enhance intra- and interobserver agreement of scoring and its accuracy. STUDY DESIGN: Validation study using equine cadaver tissue. METHODS: Osteochondral samples (n = 99) were prepared from 18 equine metacarpophalangeal joints and imaged using OCT. Custom-made software was developed for semi-automated ICRS scoring of cartilage lesions on OCT images. Scoring was performed visually and semi-automatically by five observers, and levels of inter- and intraobserver agreement were calculated. Subsequently, OCT-based scores were compared with ICRS scores based on light microscopy images of the histological sections of matching locations (n = 82). RESULTS: When semi-automated scoring of the OCT images was performed by multiple observers, mean levels of intraobserver and interobserver agreement were higher than those achieved with visual OCT scoring (83% vs. 77% and 74% vs. 33%, respectively). Histology-based scores from matching regions of interest agreed better with visual OCT-based scoring than with semi-automated OCT scoring; however, the accuracy of the software was improved by optimising the threshold combinations used to determine the ICRS score. MAIN LIMITATIONS: Images were obtained from cadavers. CONCLUSIONS: Semi-automated scoring software improved the reproducibility of ICRS scoring of chondral lesions in OCT images and made scoring less observer-dependent. The image analysis and segmentation techniques adopted in this study warrant further optimisation to achieve better accuracy with semi-automated ICRS scoring. In addition, studies on in vivo applications are required.

Incidence of severe local anaesthetic toxicity and adoption of lipid rescue in Finnish anaesthesia departments in 2011-2013.

BACKGROUND: Although the incidence of severe local anaesthetic systemic toxicity (LAST) has been declining, the risk of LAST still remains. There are no national treatment guidelines for LAST in Finland. We performed a national survey of the occurrence of LAST and its treatment in 2011-2013. METHODS: A structured electronic questionnaire was sent to the anaesthesia department chiefs of all Finnish public hospitals (n = 45) in spring 2014. We collected information about the occurrence and outcome of LASTs and existence of treatment protocols. RESULTS: The questionnaire response rate was 100% covering approximately 95% of all regional anaesthesias managed by anaesthesiologists in Finnish hospitals. The total number of regional anaesthesias, excluding spinal anaesthesia, performed by anaesthesiologists was approximately 211,700 during the survey period. Fifteen cases of LAST were reported (0.7 : 10,000); all patients recovered without negative sequelae. Fourteen patients, in five of whom ultrasound guidance had been applied, developed central nervous system toxicity symptoms and only one cardiac symptoms. Lipid emulsion was given to this latter patient, and to four of the other 14. The relative risk (95% confidence intervals) for occurrence of LAST in non-academic hospital vs. university hospitals was 3.3 (1.0-10.3; P = 0.04). Treatment protocols for LAST included lipid emulsion in 47% of the departments. CONCLUSIONS: The incidence of LAST in Finland is very low. Several departments have adopted lipid emulsion treatment for LAST despite lack of national recommendations and knowledge of the possible mechanism of action.

Chloroprocaine 40 mg produces shorter spinal block than articaine 40 mg in day-case knee arthroscopy patients.

BACKGROUND: Articaine and chloroprocaine have recently gained interest as short-acting spinal anaesthetics. Based on previous work comparing articaine 60 mg with chloroprocaine 40 mg, we hypothesised that articaine 40 mg and chloroprocaine 40 mg would produce similar spinal anaesthesa regarding block onset, maximal spread, and recovery. METHODS: In this randomised, double-blind study, adult patients (18-70 years, American Society of Anaesthesiologists physical status I-III, BMI < 36 kg/m(2) ) scheduled for day-case knee arthroscopy received either articaine 40 mg (20 mg/ml) (group A40, n = 16) or chloroprocaine 40 mg (20 mg/ml) (group C40, n = 18) intrathecally. Telephone interviews were performed on the first and seventh postoperative day to disclose possible side effects, e.g. transient neurological symptoms (TNS). RESULTS: The groups were comparable regarding demographic data, onset and maximal spread of spinal anaesthesia, and duration of surgery. Surgery could be performed successfully under spinal anaesthesia except once in A40 (insufficient block) and once in C40 (prolonged surgery). Complete recovery was significantly slower in A40 vs. C40 for both motor block (105 (94/120) vs. 75 (71/90) min) [P < 0.001, Mann-Whitney U-test (MW-U)] and sensory block [135 (109/176) vs. 105 min (90/124)] (P < 0.02, MW-U), respectively [data are median (25th/75th percentiles)]. One patient from A40 showed mild TNS. CONCLUSION: Both A40 and C40 provided mainly adequate spinal anaesthesia for day-case knee arthroscopy. While onset and maximal spread were comparable, the recovery from motor block was clearly faster with chloroprocaine after equivalent doses of spinal articaine and chloroprocaine.

Serious complications associated with spinal and epidural anaesthesia in Finland from 2000 to 2009.

BACKGROUND: Analyses of closed claims provide insight into the characteristics of rare complications. Serious complications related to spinal and epidural blocks are relatively rare. In Finland, all malpractice cases are primarily handled by the Patient Insurance Centre (PIC) within a 'no-fault scheme'. METHODS: All claims attributed to central neuraxial blocks and settled by the PIC during the period, 2000-2009 were analysed. The number of spinal and epidural procedures performed during this time was estimated based on a questionnaire sent to all surgical hospitals in Finland in 2009, surveying the numbers and types of neuraxial blocks carried out in 2008. RESULTS: During the study period, 216 closed claims were flagged with spinal or epidural blocks. In 41 of 216 instances, the neuraxial block was apparently responsible for a serious (fatal or critical or lasting >1 year) complication. These included six fatalities and 13 epidural haematomata (two in conjunction with fondaparinux, three with excessive doses of low molecular weight heparins, six where present guidelines were not observed). Fatalities occurred in 1 : 775,000 spinals for surgery, 1 : 62,000 in epidurals for surgery or acute pain relief, 1 : 12,000 epidurals for chronic pain relief, 1 : 89,000 in combined spinal and epidural for surgery, and 1 : 144,000 epidurals for labour. The incidence of neuraxial haematoma after spinal block was 1 : 775,000, that for epidural block 1 : 26,400, and in the case of combined spinal and epidural, 1 : 17,800. Irrespective of the method of neuraxial technique, the majority of patients suffering serious complications were the elderly having comorbidities. CONCLUSIONS: In this closed claims analysis, major problems related to neuraxial blocks were rare. Epidural or a combined spinal and epidural technique resulted in more complications than did spinal procedure.

Local infiltration analgesia with levobupivacaine compared with intrathecal morphine in total hip arthroplasty patients.

BACKGROUND: Recently, local infiltration analgesia (LIA) has been promoted for pain control after total hip arthroplasty (THA). We hypothesized that LIA would offer equal analgesic efficacy but less adverse effects, e.g., nausea and vomiting, when compared with an established regimen [intrathecal morphine (it-M)] after THA. METHODS: This randomized controlled trial comprised 60 patients undergoing THA under spinal anaesthesia. For LIA, the surgeon administered levobupivacaine, ketorolac and epinephrine at the surgical site intraoperatively. LIA patients received a LIA top-up through a wound catheter on the morning of the 1st post-operative day (POD). In group it-M, 0.1 mg morphine was given together with the spinal anaesthetic. Study parameters included pain scores, vital parameters and side effects, e.g., post-operative nausea and vomiting (PONV). Besides, levobupivacaine plasma concentrations were determined in 10 LIA patients. RESULTS: The median (25th/75th percentiles) rescue oxycodone demand differed significantly with LIA 15 (10/25) mg vs. 8.5 (1.5/15) mg with it-M (P < 0.006) during the day of surgery, but not anymore on 1st or 2nd POD. The LIA top-up had no effect. However, both analgesic regimens resulted in comparable pain scores and patient satisfaction. PONV incidence and medication did not vary significantly. LIA offered certain advantages regarding early post-operative mobilization. Maximum levobupivacaine plasma concentrations (229-580 ng/ml) remained under the toxic level. CONCLUSIONS: While LIA might enable earlier mobilization after THA, it was not associated with less nausea as compared with it-M. Less rescue oxycodone was given early after it-M, but urinary retention was more common in that group.

Neuraxial techniques in patients with pre-existing back impairment or prior spine interventions: a topical review with special reference to obstetrics.

Many anaesthetists consider neurological disorders of all kinds as a contraindication for regional anaesthesia particularly for neuraxial techniques. This hesitation is partly rooted in fears of medicolegal problems but also in the heterogeneous literature. Therefore, the present topical review is an attempt to describe the feasibility and the risks of neuraxial techniques in patients with spinal injury, anatomical compromise, chronic back pain or previous spinal interventions, ranging from 'minor' types like epidural blood patches to major surgery such as Harrington fusions. Most reviews and case reports were describing experiences in obstetrics as these patients are more likely to insist on neuraxial blocks. In the acute phase of new neurologic injury, general anaesthesia may be the technique of choice to prevent further haemodynamic and respiratory deterioration. After the acute phase, current evidence is mostly reassuring with respect to the risks of neuraxial blocks as they may even be recommendable in some conditions. Ultrasound technology may be of additional help to increase the success rate. A careful pre-operative examination remains mandatory, while patients should be sufficiently informed about technical aspects and possible relapses or progression of their disease. When necessary, patients should have additional technical and clinical examinations as close as possible to surgery to establish the actual pre-operative status. Most patients may benefit more from spinal techniques rather than from less reliable epidural ones. High concentrations and volumes of local anaesthetics should be avoided at all times, especially in patients with nerve compression, large disc herniation or spinal stenosis.

Chloroprocaine vs. articaine as spinal anaesthetics for day-case knee arthroscopy.

BACKGROUND: Chloroprocaine and articaine have recently gained interest as short-acting spinal anaesthetics. They have not, however, previously been compared in an ambulatory surgery setting. METHODS: In this double-blind, randomised, controlled trial, adult patients (≤65 years, ASA I-II, body mass index<36 kg/m2) underwent day-case knee arthroscopy under spinal anaesthesia with either 40 mg of plain chloroprocaine (20 mg/ml) (group C40; n=39) or 60 mg of plain articaine (40 mg/ml) (group A60; n=39). Study parameters included the onset, degree, and regression of both sensory and motor block. Standardised telephone interviews on the first and seventh post-operative day were aimed at detecting any untoward sequelae, e.g., transient neurologic symptoms (TNSs). RESULTS: The groups were comparable regarding demographic data, onset and maximal spread of spinal anaesthesia, and duration of surgery. All arthroscopies were performed successfully under spinal anaesthesia, except for one patient (C40, unforeseen delay in the start of surgery). The duration of sensory block≥dermatome L1 was significantly shorter in C40 vs. A60. Correspondingly, complete recovery was significantly faster (P<0.0001, Mann-Whitney U-test) in C40 vs. A60 for both motor [75 (60/90) vs. 135 (105/150) min] and sensory [105 (105/135) vs. 165 (135/180) min] block, respectively [data are median (25th/75th percentiles)]. No TNSs were noted. CONCLUSIONS: Both anaesthetics used provided a rapid onset of spinal anaesthesia of about 1 h and were satisfactory for day-case knee arthroscopy. Recovery, however, was significantly faster in group C40. The data add to earlier results that TNSs seem to be uncommon after spinal chloroprocaine and articaine.

Unilateral spinal anaesthesia for outpatient surgery: a comparison between hyperbaric bupivacaine and bupivacaine-clonidine combination.

BACKGROUND: Low-dose hyperbaric bupivacaine has been used to produce unilateral spinal anaesthesia for outpatient surgery. Unilateral spinal anaesthesia is associated with reduction of hypotension, faster recovery and increased patient satisfaction. Small doses of clonidine have shown effectiveness in intensifying spinal anaesthesia. We investigated the effect of adding 15 microg of clonidine to 5 mg hyperbaric bupivacaine on unilaterality. METHODS: Sixty patients undergoing outpatient knee arthroscopy were randomly allocated to receive either 1.2 ml (6 mg) of hyperbaric bupivacaine or a 1.2 ml solution containing 1.0 ml (5 mg) hyperbaric bupivacaine, 0.1 ml (75 microg) clonidine and 0.1 ml sterile water. The motor block was assessed by a modified Bromage scale and the sensory block by a pinprick. RESULTS: There was a significant difference in the spread of anaesthesia between the operated and contralateral sides in both groups. Seventy-seven per cent of the blocks were unilateral in group B and 73% in group B-C. There was no significant difference between the groups, in unilaterality. The motor block was prolonged in group B-C but it did not affect home-readiness. Patients receiving clonidine needed more vasopressors. There was a significant difference in blood pressures between the groups, being lower in group B-C after 1 h 45 min. CONCLUSION: Using 5 mg hyperbaric bupivacaine with 15 microg of clonidine, the unilaterality can be achieved and spinal anaesthesia intensified without affecting home-readiness. More vasopressors are needed in the beginning, but after the surgery patients experienced less pain.

Spinal 2-chloroprocaine: effective dose for ambulatory surgery.

BACKGROUND: There is an interest in finding a safe, short-acting spinal anaesthetic, suitable for ambulatory surgery. In this prospective study, we evaluated the effective dose of plain 2-chloroprocaine (2-CP) for lower limb surgery, including knee arthroscopy and saphenectomy. METHODS: Sixty-four ASA physical status I-III patients undergoing elective lower limb surgery were randomly allocated to one of the four local anaesthetic groups for spinal anaesthesia in a double-blind manner. The patients (n=16 patients in each group) received 35, 40, 45 or 50 mg of 10 mg/ml isobaric 2-CP. RESULTS: In all patients, anaesthesia was sufficient for the planned surgery. The median peak block height (T9) was similar in all four groups (P=0.66). Time to complete sensory block regression was faster in the 35 mg group (111 min, mean) and in the 40 mg group (108 min) than in the 50 mg group (134 min, P=0.005). No differences in time to complete motor block regression were observed (P=0.3). Home discharge time was faster in the 35 mg group (123 min) and in the 40 mg group (122 min) than in the 50 mg group (165 min, P=0.001). No complications related to spinal anaesthesia were observed and no transient neurologic symptoms (TNS) were reported at the 3-day follow-up. CONCLUSION: Spinal 2-CP, 10 mg/ml 35, 40, 45 and 50 mg provide reliable sensory and motor block for ambulatory surgery, while reducing the dose of 2-CP to 35 and 40 mg resulted in a spinal block of faster ambulation.

Clinical validation of the LKB model and parameter sets for predicting radiation-induced pneumonitis from breast cancer radiotherapy.

The choice of the appropriate model and parameter set in determining the relation between the incidence of radiation pneumonitis and dose distribution in the lung is of great importance, especially in the case of breast radiotherapy where the observed incidence is fairly low. From our previous study based on 150 breast cancer patients, where the fits of dose-volume models to clinical data were estimated (Tsougos et al 2005 Evaluation of dose-response models and parameters predicting radiation induced pneumonitis using clinical data from breast cancer radiotherapy Phys. Med. Biol. 50 3535-54), one could get the impression that the relative seriality is significantly better than the LKB NTCP model. However, the estimation of the different NTCP models was based on their goodness-of-fit on clinical data, using various sets of published parameters from other groups, and this fact may provisionally justify the results. Hence, we sought to investigate further the LKB model, by applying different published parameter sets for the very same group of patients, in order to be able to compare the results. It was shown that, depending on the parameter set applied, the LKB model is able to predict the incidence of radiation pneumonitis with acceptable accuracy, especially when implemented on a sub-group of patients (120) receiving [see text]|EUD higher than 8 Gy. In conclusion, the goodness-of-fit of a certain radiobiological model on a given clinical case is closely related to the selection of the proper scoring criteria and parameter set as well as to the compatibility of the clinical case from which the data were derived.

The connection between age, job control and sickness absences among Finnish food workers.

METHODS: The relationship between sickness absence and job control among industrial food workers of different ages (n = 114) was studied. RESULTS: The number of absence spells, particularly short absence spells, was higher among younger workers, as expected. Using multivariate analysis, low job control was associated with an increased number of all absence spells (P < 0.02). CONCLUSIONS: Job control may be an important factor in determining sickness absence among industrial workers.

Segmental lumbar spine instability at flexion-extension radiography can be predicted by conventional radiography.

AIM: To identify plain radiographic findings that predict segmental lumbar spine instability as shown by functional flexion-extension radiography. MATERIALS AND METHODS: Plain radiographs and flexion-extension radiographs of 215 patients with clinically suspected lumbar spine instability were analysed. Instability was classified into anterior or posterior sliding instability. The registered plain radiographic findings were traction spur, spondylarthrosis, arthrosis of facet joints, disc degeneration, retrolisthesis, degenerative spondylolisthesis, spondylolytic spondylolisthesis and vacuum phenomena. Factors reaching statistical significance in univariate analyses (P < 0.05) were included in stepwise multiple logistic regression analysis. RESULTS: Degenerative spondylolisthesis (P = 0.004 at L3-4 level and P = 0.017 at L4-5 level in univariate analysis and odds ratio 16.92 at L4-5 level in multiple logistic regression analyses) and spondylolytic spondylolisthesis (P = 0.003 at L5-S1 level in univariate analyses) were the strongest independent determinants of anterior sliding instability. Retrolisthesis (odds ratio 10.97), traction spur (odds ratio 4.45) and spondylarthrosis (odds ratio 3.20) at L3-4 level were statistically significant determinants of posterior sliding instability in multivariate analysis. CONCLUSION: Sliding instability is strongly associated with various plain radiographic findings. In mechanical back pain, functional flexion-extension radiographs should be limited to situations when symptoms are not explained by findings of plain radiographs and/or when they are likely to alter therapy.

Quality assurance in radiotherapy of breast cancer--variability in planning target volume delineation.

The inter-physician and inter-patient variability in planning target volume delineation for the radiotherapy of breast cancer after conservative surgery is presented. Eleven experienced radiation oncologists determined the planning target volume (PTV) for four breast cancer patients. Delineation was based on CT slices taken at intervals of 15 mm. The variability in target volume delineation was determined by measuring the volumes in units of cc and the position of the drawn PTVs. Statistical analysis was based on X/R-charts and on Pareto chart and analysis. The maximum range in PTV for one patient was from 670 to 1,200 cc. The observations of three physicians were in excess of the warning limit altogether 18 times. The methods used in this study clearly reveal inter-physician variability in PTV delineation and widest variations found are not acceptable. Training targeted to some physicians and more detailed and unambiguous protocols for PTV delineation are needed.

Patient-controlled epidural analgesia versus continuous epidural analgesia after total knee arthroplasty.

BACKGROUND: Patient-controlled epidural analgesia (PCEA) has been found to be an effective method for pain relief during labour and after surgery. The goal of this study was to compare the efficacy of bupivacaine-fentanyl PCEA and continuous epidural infusion with the same mixture for treatment of pain after total knee arthroplasty. METHODS: Fifty-four patients under spinal anaesthesia were allocated to two groups in this randomized, double-blind study: the PCEA group could demand a bolus of 0.05 ml/kg of the bupivacaine 1.1 mg/ml and fentanyl 5 microg/ml solution, with a lockout interval of 10 min and total dose limit of three bolus doses per hour. The EPI group received a continuous infusion of 0.1 ml kg(-1) h(-1) of the same bupivacaine-fentanyl solution, and only a minimal extra bolus dose of 0.2 ml with the same lockout interval. All the patients received also paracetamol 1 g, orally, three times a day. In addition to pain scores at rest and during leg lifting, the 20-h analgesic consumption and the incidence of side effects were recorded. RESULTS: Forty-nine patients completed the study. The bupivacaine and fentanyl consumption during 20 h was smaller in the PCEA group (P<0.001). Analgesia and the need for rescue-opioid medication were similar in both groups. There were no differences between the PCEA and EPI groups regarding the incidence of side effects. Five patients were confused about how to operate the PCEA apparatus. CONCLUSION: The amount of bupivacaine-fentanyl solution consumed was significantly less with PCEA than with continuous infusion of bupivacaine-fentanyl solution without affecting the quality of postoperative analgesia after total knee arthroplasty. Several of the elderly patients had difficulties in operating the PCEA apparatus.

Comparison of technical and block characteristics of different combined spinal and epidural anesthesia techniques.

BACKGROUND AND OBJECTIVES: The combined spinal and epidural (CSE) technique can reduce or eliminate some of the disadvantages of spinal and epidural anesthesia, while still preserving their advantages. CSE anesthesia is now commonly performed with a single-segment needle-through-needle technique; however, this technique involves some controversies about needle handling and the risk of catheter migration. To avoid some of these potential problems, special CSE sets have been produced. In the present study, 2 of these sets were compared with the traditional double-segment technique. METHODS: Ninety patients undergoing orthopedic surgery of the lower extremity were randomly allocated into 3 groups of equal size: Group 1, CSE set with an interlocking device between the spinal and epidural needle; group 2, CSE set with a "backeye" at the epidural needle curve for the passage of the spinal needle; group 3, double-segment technique. All epidural needles were 18-gauge, and spinal needles were 27-gauge with a pencil-point tip. In groups 1 and 2, the puncture was performed at the L3-4 interspace, and in group 3 the epidural catheter was first inserted at the L2-3 interspace followed by spinal puncture one interspace lower. Hyperbaric 0.5% bupivacaine, 2 mL, was used for the spinal block, and 4 mL of 2% lidocaine with epinephrine through the epidural catheter was used as a test dose. The block performance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Postoperatively, a bolus of epidural morphine 2 to 4 mg was used for the control of postoperative pain. All patients were interviewed on the 1st and the 7th postoperative days. Afterwards, the needles and catheters were examined by microscopy. RESULTS: The frequency of the successful CSE block was higher in groups 3 (100%) and 2 (90%) than in group 1 (63%) (P <.05). The mean duration of successful block performance, as well as the median level of analgesia, were similar in all the groups. One case of epidural catheter migration intrathecally was observed (group 1). Postoperative nausea and vomiting occurred in 23% of patients, and the incidence of postdural puncture headache was 2.2%. The incidence of backache at the puncture site was similar in the groups. Microscopy showed 6 distorted spinal needle tips (all in group 1), but no material damage to the epidural catheters. CONCLUSIONS: The use of the CSE sets does not seem to save time compared with the double-segment technique. Technical problems, unsuccessful CSE block, and damaged spinal needle tip were noted relatively often with the interlocking CSE set. Anesthetic characteristics in the successful blocks were similar with the different techniques.

Comparison of three catheter sets for continuous spinal anesthesia in patients undergoing total hip or knee arthroplasty.

BACKGROUND AND OBJECTIVES: Continuous spinal anesthesia (CSA) with microcatheters may be complicated because of technical problems. In elderly patients, some of the problems may be solved by using thicker catheters. A recent invention, involving a catheter-over-needle system, may prevent leakage of cerebrospinal fluid (CSF) and may also improve the prediction of the intrathecal position of the catheter tip. METHODS: This study included 90 patients undergoing primary hip or knee replacement, randomly allocated into 3 groups, with 30 patients in each group: Group EC, a 24-gauge epidural catheter through a 19-gauge Tuohy needle; group MC, a 28-gauge microcatheter through a 22-gauge spinal needle; group SC, a 22-gauge spinal catheter over a 27-gauge spinal needle through an epidurally placed 18-gauge Crawford needle. All subarachnoid catheterizations were performed with the patient in the lateral position and the initial spinal block dose was 2 mL of plain 0.5% bupivacaine. Increments of 0.5 mL were administered when required. The block performance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Catheter function during the postoperative infusion was assessed. Afterwards the needles and catheters were examined by microscopy. RESULTS: The frequency of the successful catheterization was higher in the EC and MC groups (90% in each) than in the SC group (63%) (P <.05). The mean duration of the successful catheterizations, as well as the median level of analgesia, were similar in the groups. The postoperative infusion had to be stopped in 3, 1, and 1 patients in groups EC, MC, and SC, respectively, because of a technical reason. No neurologic sequelae occurred in this study. Microscopy showed 4 distorted spinal needle tips (2 each with MC and SC) and minor material damage of the SC catheters when bone had been met during block performance. CONCLUSIONS: Placement of the SC catheters was unsuccessful to a high degree, and bone contact produced distortion of the tip of some of these catheters. Otherwise, the quality associated with catheterization time, anesthetic distribution, and catheter function was similar with the 3 catheters.

A low dose of plain or hyperbaric bupivacaine for unilateral spinal anesthesia.

BACKGROUND AND OBJECTIVES: Unilateral spinal anesthesia may be advantageous, especially in the outpatient setting. A low dose of anesthetic solution, pencil-point needle, low speed of intrathecal injection, and a lateral position have been reported to facilitate the production of unilateral distribution of spinal anesthesia. We compared the effects of plain and hyperbaric bupivacaine in attempting to obtain a unilateral spinal anesthesia for patients undergoing outpatient knee arthroscopy. METHODS: Sixty patients were randomly allocated to 2 groups to receive either 1.2 mL (6 mg) of plain 0.5% bupivacaine (group 1; n = 30) or 1.2 mL (6 mg) of hyperbaric 0.5% bupivacaine in 8% glucose (group 2; n = 30). Drugs were administered at the L2-3 interspace with the patient in the lateral position. Patients remained in this position for 20 minutes before being turned supine for the operation. Spinal block was assessed by pinprick and modified Bromage scale and compared between the operated and nonoperated sides. RESULTS: There was a significant difference between the operated and nonoperated side in both groups at all testing times, but a more unilateral spinal block was achieved with hyperbaric bupivacaine. Unilateral motor and sensory block was observed in 25 patients in group 2 (83%) and in 11 patients in group 1 (37%) (P <.01). The hemodynamic changes were minimal, since hypotension occurred only in 5.0% and bradycardia in 1.7% of all patients. CONCLUSION: In conclusion, the spinal anesthesia in both groups are suitable alternatives for adult outpatient knee arthroscopies, but hyperbaric bupivacaine provides us with a more unilateral spinal block.