Comparison of peripheral nerve blockade characteristics between non-diabetic patients and patients suffering from diabetic neuropathy: a prospective cohort study.

Animal data have demonstrated increased block duration after local anaesthetic injections in diabetic rat models. Whether the same is true in humans is currently undefined. We, therefore, undertook this prospective cohort study to test the hypothesis that type-2 diabetic patients suffering from diabetic peripheral neuropathy would have increased block duration after ultrasound-guided popliteal sciatic nerve block when compared with patients without neuropathy. Thirty-three type-2 diabetic patients with neuropathy and 23 non-diabetic control patients, scheduled for fore-foot surgery, were included prospectively. All patients received an ultrasound-guided popliteal sciatic nerve block with a 30 ml 1:1 mixture of lidocaine 1% and bupivacaine 0.5%. The primary outcome was time to first opioid request after block procedure. Secondary outcomes included the time to onset of sensory blockade, and pain score at rest on postoperative day 1 (numeric rating scale 0-10). These outcomes were analysed using an accelerated failure time regression model. Patients in the diabetic peripheral neuropathy group had significantly prolonged median (IQR [range]) time to first opioid request (diabetic peripheral neuropathy group 1440 (IQR 1140-1440 [180-1440]) min vs. control group 710 (IQR 420-1200 [150-1440] min, p = 0.0004). Diabetic peripheral neuropathy patients had a time ratio of 1.57 (95%CI 1.10-2.23, p < 0.01), experienced a 59% shorter time to onset of sensory blockade (median time ratio 0.41 (95%CI 0.28-0.59), p < 0.0001) and had lower median (IQR [range]) pain scores at rest on postoperative day 1 (diabetic peripheral neuropathy group 0 (IQR 0-1 [0-5]) vs. control group 3 (IQR 0-5 [0-9]), p = 0.001). In conclusion, after an ultrasound-guided popliteal sciatic nerve block, patients with diabetic peripheral neuropathy demonstrated reduced time to onset of sensory blockade, with increased time to first opioid request when compared with patients without neuropathy.

Efficacy of perineural vs systemic dexamethasone to prolong analgesia after peripheral nerve block: a systematic review and meta-analysis.

Perineural dexamethasone has gained popularity in regional anaesthesia to prolong the duration of analgesia, but its advantage over systemic administration is disputed. The objective of this meta-analysis was to compare the analgesic efficacy of both routes of administration during peripheral nerve block. The methodology followed the PRISMA statement guidelines. The primary outcome was the duration of analgesia analysed according to the type of local anaesthetic administered (bupivacaine or ropivacaine). Secondary outcomes included cumulative opioid consumption in morphine i.v. equivalents, pain scores, and complication rates (neurological complications, infection, or hyperglycaemia). Eleven controlled trials, including 914 patients, were identified. The duration of analgesia was significantly increased with perineural dexamethasone vs systemic dexamethasone by a mean difference of 3 h [95% confidence interval (CI): 1.4, 4.5 h; P=0.0001]. Subgroup analysis revealed that the duration of analgesia was increased by 21% with bupivacaine (mean difference: 4.0 h; 95% CI: 2.8, 5.2 h; P<0.00001) and 12% with ropivacaine (mean difference: 2.0 h; 95% CI: -0.5, 4.5 h; P=0.11). The quality of evidence for our primary outcome was moderate according to the GRADE system. There were no significant differences in other secondary outcomes. No neurological complications or infections were reported. Glucose concentrations were not increased when dexamethasone was injected systemically, but this outcome was reported by only two trials. There is, therefore, moderate evidence that perineural dexamethasone combined with bupivacaine, but not ropivacaine, slightly prolongs the duration of analgesia, without an impact on other pain-related outcomes, when compared with systemic dexamethasone. Injection of perineural dexamethasone should be cautiously balanced in light of the off-label indication for this route of administration.

The analgesic efficacy of sciatic nerve block in addition to femoral nerve block in patients undergoing total knee arthroplasty: a systematic review and meta-analysis.

The aim of this meta-analysis was to assess the postoperative analgesic efficacy of sciatic nerve block when combined with femoral nerve block after total knee arthroplasty. Outcomes included resting pain scores (analogue scale, 0-100), intravenous morphine consumption at 12 h, 24 h and 48 h postoperatively, and functional outcomes comprising knee flexion, distance walked, and length of stay. Twelve randomised controlled trials were included, with a total of 600 patients. When combined with femoral nerve block, sciatic nerve block significantly reduced resting pain scores at 12 h postoperatively with a mean difference of 10 (95% CI: -15 to -5; p < 0.00001). Resting pain scores at 24 h, and intravenous morphine consumption at 12 h, 24 h and 48 h postoperatively were also significantly reduced, but without clinical significance beyond 12 h and without affecting functional outcomes. In conclusion, sciatic nerve block confers additional postoperative analgesia within the first 12 postoperative hours compared with femoral nerve block alone for patients undergoing total knee arthroplasty.

[Effect of contact lenses and visual acuity on the registration of saccadic eye movements using an infrared reflection method]. / Der Einfluss von Kontaktlinsen und Sehschärfe auf die Registrierung sakkadischer Augenbewegungen mit der Infrarot-Reflexionsmethode.

In order to examine the influence of contact lenses and visual acuity on recordings of saccadic eye movements with the infrared reflection method, horizontal 20 and 30 degrees saccades were recorded with and without contact lenses in 16 subjects (32 eyes) usually wearing contact lenses. As far as the main parameters of the saccades (accuracy, peak velocity and duration) were concerned, the reliability of the measurements (recognizable through the mean values) was not essentially influenced by the contact lenses. The precision of the measurements (recognizable through the standard deviation) was with the contact lenses significantly but, for clinical use, not essentially worse. The velocity waveforms of the saccades, however, were considerably changed by contact lenses in some cases. This is why examinations, in which saccadic velocity waveforms are used for diagnosis, should be performed without contact lenses. Visual acuity had no measurable influence on the main parameters of the saccades. However, considerably more corrective saccades were observed with contact lenses than without. There were reasons to believe that not the contact lenses themselves, but better visual acuity was responsible for the larger number of corrective saccades.