The analgesic effect of a popliteal plexus blockade after total knee arthroplasty: A feasibility study.

INTRODUCTION: An obturator nerve block (ONB) and a femoral triangle block (FTB) provide effective analgesia after total knee arthroplasty (TKA) without impeding the ambulation, although the ONB produces motor blockade of the hip adductor muscles. The popliteal plexus (PP) in the popliteal fossa is formed by contribution from the tibial nerve and the posterior obturator nerve, innervating intraarticular genicular structures and the posterior capsule of the knee. We hypothesised that a popliteal plexus block (PPB) as a supplement to an FTB would reduce pain after TKA without anaesthetising motor branches from the sciatic nerve in the popliteal fossa. AIM: To assess the analgesic effect of adding a PPB to an FTB in 10 subjects with significant pain after TKA. METHODS: All subjects underwent unilateral TKA with spinal anaesthesia and received an FTB. The cutaneous sensation and the postoperative pain were assessed. The primary outcome was the proportion of subjects with pain above numeric rating scale (NRS) 3 followed by a reduction to NRS 3 or below after conducting a PPB. RESULTS: Ten subjects with a median pain of NRS 5.5 (interquartile range [IQR] 4-8) after unilateral TKA received a PPB. All 10 subjects experienced a reduction in pain to NRS 3 or below (NRS 1.5 [IQR 0-3]) within a mean time of 8.5 (95% CI 6.8-10.2) minutes. Three subjects were completely pain free after the PPB. The ankle muscle strength was not affected. CONCLUSIONS: The PPB provided effective pain relief without affecting the ankle muscle strength in all 10 subjects with significant pain after TKA and an FTB.

Spread of injectate around hip articular sensory branches of the femoral nerve in cadavers.

BACKGROUND: Anatomical knowledge dictates that regional anaesthesia after total hip arthroplasty requires blockade of the hip articular branches of the femoral and obturator nerves. A direct femoral nerve block increases the risk of fall and impedes mobilisation. We propose a selective nerve block of the hip articular branches of the femoral nerve by an ultrasound-guided injection in the plane between the iliopsoas muscle and the iliofemoral ligament (the iliopsoas plane). The aim of this study was to assess whether dye injected in the iliopsoas plane spreads to all hip articular branches of the femoral nerve. METHODS: Fifteen cadaver sides were injected with 5 mL dye in the iliopsoas plane guided by ultrasound. Dissection was performed to verify the spread of injectate around the hip articular branches of the femoral nerve. RESULTS: In 10 dissections (67% [95% confidence interval: 38-88%]), the injectate was contained in the iliopsoas plane staining all hip articular branches of the femoral nerve without spread to motor branches. In four dissections (27% [8-55%]), the injection was unintentionally made within the iliopectineal bursa resulting in secondary spread. In one dissection (7% [0.2-32%]) adhesions partially obstructed the spread of dye. CONCLUSION: An injection of 5 mL in the iliopsoas plane spreads around all hip articular branches of the femoral nerve in 10 of 15 cadaver sides. If these findings translate to living humans, injection of local anaesthetic into the iliopsoas plane could generate a selective sensory nerve block of the articular branches of the femoral nerve without motor blockade.

The effect of perineural dexamethasone on duration of sciatic nerve blockade: a randomized, double-blind study.

BACKGROUND: Major hindfoot and ankle surgery is associated with severe postoperative pain, which is effectively alleviated by combined sciatic and saphenous nerve blockade. Local anaesthetics with added dexamethasone consistently prolongs the duration of pain relief compared to local anaesthetics alone. However, whether the extended duration of pain relief is due to an effect on duration of sensorimotor block per se vs. systemic absorption of the dexamethasone is still not fully elucidated. We aimed to investigate the postoperative duration of sensorimotor blockade with either dexamethasone or saline added to bupivacaine-epinephrine. METHODS: Fifty six patients scheduled for surgery were randomly assigned to a popliteal sciatic nerve block of 18 ml 0.5% bupivacaine-epinephrine with either 2 ml of 0.4% dexamethasone or 2 ml 0.9% normal saline added. Sensory and motor functions were tested every 30 min until normalized nerve functions. Primary outcome was time until complete return of sensorimotor functions. RESULTS: Mean (SD) time until return of normal sensory and motor functions was 26 (6) vs. 16 (4) hours, P < 0.001, postponing block remission by 10 (95% CI: 8-13) hours. Mean (SD) time until first opioid request was 34 (11) vs. 15 (7) hours, P < 0.001, extending first opioid request by 19 (95% CI: 13-25) hours. Total oral morphine equivalents administered 0-48 h differed significantly between the two groups by 39 (95% CI: 23-55) mg. CONCLUSIONS: Addition of 8 mg dexamethasone to 0.5% bupivacaine-epinephrine significantly prolongs the duration of sensorimotor popliteal sciatic nerve blockade, and reduces pain and opioid consumption in patients after major hind foot and ankle surgery.

Ultrasound-guided lumbar plexus block in volunteers; a randomized controlled trial.

Background: The currently best-established ultrasound-guided lumbar plexus block (LPB) techniques use a paravertebral location of the probe, such as the lumbar ultrasound trident (LUT). However, paravertebral ultrasound scanning can provide inadequate sonographic visibility of the lumbar plexus in some patients. The ultrasound-guided shamrock LPB technique allows real-time sonographic viewing of the lumbar plexus, various anatomical landmarks, advancement of the needle, and spread of local anaesthetic injectate in most patients. We aimed to compare block procedure outcomes, effectiveness, and safety of the shamrock vs LUT. Methods: Twenty healthy men underwent ultrasound-guided shamrock and LUT LPBs (2% lidocaine­adrenaline 20 ml, with 1 ml diluted contrast added) in a blinded randomized crossover study. The primary outcome was block procedure time. Secondary outcomes were procedural discomfort, number of needle insertions, injectate spread assessed with magnetic resonance imaging, sensorimotor effects, and lidocaine pharmacokinetics. Results: The shamrock LPB procedure was faster than LUT (238 [sd 74] vs 334 [156] s; P=0.009), more comfortable {numeric rating scale 0­10: 3 [interquartile range (IQR) 2­4] vs 4 [3­6]; P=0.03}, and required fewer needle insertions (2 [IQR 1­3] vs 6 [2­12]; P=0.003). Perineural injectate spread seen with magnetic resonance imaging was similar between the groups and consistent with motor and sensory mapping. Zero/20 (0%) and 1/19 (5%) subjects had epidural spread after shamrock and LUT (P=1.00), respectively. The lidocaine pharmacokinetics were similar between the groups. Conclusions: Shamrock was faster, more comfortable, and equally effective compared with LUT. Clinical trial registration: NCT02255591

Displacement of popliteal sciatic nerve catheters after major foot and ankle surgery: a randomized controlled double-blinded magnetic resonance imaging study.

BACKGROUND: Popliteal sciatic nerve catheters (PSNCs) are associated with a high frequency of displacement. We aimed to estimate the frequency of catheter displacement after 48 h with magnetic resonance imaging (MRI) in patients with PSNCs after major foot and ankle surgery randomized to catheter insertion either with a short-axis in-plane (SAX-IP) approach perpendicular to the nerve or with a short-axis out-of-plane (SAX-OOP) approach parallel to the nerve. METHODS: Forty patients were randomly allocated to SAX-IP or SAX-OOP PSNC. Ropivacaine 0.75% 20 ml was injected via the catheter followed by ropivacaine 0.2% 10 ml h(-)1 infusion. Correct primary catheter placement was ensured after initial injection of local anaesthetic via the catheter. Forty-eight hours after insertion, MRI was performed after injection of saline with added contrast (Dotarem) via the catheter. The primary outcome was catheter displacement estimated as the frequency of spread of contrast exclusively outside the paraneurium. RESULTS: All patients had correct primary catheter placement. The frequency of displacement 48 h after insertion of the PSNC was 40% when inserted perpendicular to the nerve vs 10% parallel to the nerve (difference was 30 percentage points, 95% CI: 3-53 percentage points). The relative risk of displacement was four times larger (95% CI: 0.8-10, P<0.028) in the SAX-IP vs the SAX-OOP group. The morphine consumption was 150% greater in the SAX-IP compared with the SAX-OOP group. CONCLUSION: Popliteal sciatic nerve catheters for major foot and ankle surgery inserted with ultrasound guidance parallel to the sciatic nerve have a significantly lower frequency of displacement compared with those inserted perpendicular to the nerve. CLINICAL TRIAL REGISTRATION: NCT02200016.

A randomised controlled trial of bilateral dual transversus abdominis plane blockade for laparoscopic appendicectomy.

We investigated the effects of pre-operative ultrasound-guided bilateral dual transversus abdominis plane blocks on pain when sitting up and pain at rest after laparoscopic appendicectomy. We allocated 28 participants to injection with 60 ml ropivacaine 0.375% and 28 participants to 60 ml isotonic saline. The median (IQR [range]) cumulative pain scores during the first 12 postoperative hours were less after ropivacaine than saline (maximum 120): on sitting, 34 (19-46 [0-59]) vs 50 (30-59 [0-97]), respectively, p = 0.009; and at rest, 25 (10-33 [0-49]) vs 31 (24-43 [0-72]), respectively, p = 0.035. There were no differences in morphine consumption, nausea, vomiting, time in recovery or time to walk.

A randomised controlled trial of ultrasound-guided blockade of the saphenous nerve and the posterior branch of the obturator nerve for postoperative analgesia after day-case knee arthroscopy.

The purpose of this study was to investigate the effects of blockade of the saphenous nerve and the posterior branch of the obturator nerve in addition to a standard analgesic regimen for patients discharged the same day after knee arthroscopy. The primary outcome was knee pain on flexion during the first 24 postoperative hours, calculated as area under the curve. We allocated 60 patients to ultrasound-guided nerve blocks with either ropivacaine or saline, 30 to each. The median (IQR [range]) pain score on knee flexion in the ropivacaine group 2.0 (1.1-3.7 [0.1-7.1]) was not statistically different to that in the saline group (3.3 (1.7-4.6 [0.3-6.8]), p = 0.06). There were no differences in pain at rest, opioid consumption or function.

The suprasacral parallel shift vs lumbar plexus blockade with ultrasound guidance in healthy volunteers--a randomised controlled trial.

Surgical anaesthesia with haemodynamic stability and opioid-free analgesia in fragile patients can theoretically be provided with lumbosacral plexus blockade. We compared a novel ultrasound-guided suprasacral technique for blockade of the lumbar plexus and the lumbosacral trunk with ultrasound-guided blockade of the lumbar plexus. The objective was to investigate whether the suprasacral technique is equally effective for anaesthesia of the terminal lumbar plexus nerves compared with a lumbar plexus block, and more effective for anaesthesia of the lumbosacral trunk. Twenty volunteers were included in a randomised crossover trial comparing the new suprasacral with a lumbar plexus block. The primary outcome was sensory dermatome anaesthesia of L2-S1. Secondary outcomes were peri-neural analgesic spread estimated with magnetic resonance imaging, sensory blockade of dermatomes L2-S3, motor blockade, volunteer discomfort, arterial blood pressure change, block performance time, lidocaine pharmacokinetics and complications. Only one volunteer in the suprasacral group had sensory blockade of all dermatomes L2-S1. Epidural spread was verified by magnetic resonance imaging in seven of the 34 trials (two suprasacral and five lumbar plexus blocks). Success rates of the sensory and motor blockade were 88-100% for the major lumbar plexus nerves with the suprasacral technique, and 59-88% with the lumbar plexus block (p > 0.05). Success rate of motor blockade was 50% for the lumbosacral trunk with the suprasacral technique and zero with the lumbar plexus block (p < 0.05). Both techniques are effective for blockade of the terminal nerves of the lumbar plexus. The suprasacral parallel shift technique is 50% effective for blockade of the lumbosacral trunk.

Cost-effectiveness of ultrasound vs nerve stimulation guidance for continuous sciatic nerve block.

BACKGROUND: This study assessed the cost-effectiveness of ultrasound (US) vs nerve stimulation (NS) guidance for continuous sciatic nerve block in Danish elective patients undergoing major foot and ankle surgery. METHODS: > A cost-effectiveness analysis was conducted alongside a randomized controlled trial. A total of 100 consecutive patients were randomly assigned to either traditional electrical NS or US technique for catheter insertion guidance. Information on effects and costs were collected prospectively. An incremental cost-effectiveness ratio (ICER) was calculated as the extra cost per extra successful nerve block. The robustness of the ICER was investigated using 4000 non-parametric bias-corrected bootstrap replicates to calculate the likelihood that US leads to better effect and lower costs compared with NS guidance. RESULTS: The mean ICER was negative, indicating that US was a dominating technology providing both higher quality and lower costs. The likelihood of US being more effective and cheaper than NS was estimated to 84.7%. CONCLUSIONS: In this trial, US was cost-effective. Assuming that the results are fairly generalizable, US should be the preferred catheter insertion technique in larger anaesthesia departments.

Stereological estimation of the total number of ECL cells and related parameters using the smooth, vertical fractionator in the rat oxyntic mucosa.

During the last 10 years many attempts have been made to estimate the number of enterochromaffin-like (ECL) cells in various animal studies. This is the first presentation of an unbiased stereological estimator of the total number of histamine-positive ECL cells per rat and linked to estimators of related parameters: total volume of the oxyntic mucosa, total oxyntic mucosal surface area, total oxyntic serosal surface area, surface amplification factor, average thickness of the oxyntic mucosa, total and mean volume of the ECL cells, total number of oxyntic glands and pits, mean number of ECL cells per gland, and mean number of ECL cells and glands per oxyntic serosal surface area. This study is the first application of the smooth fractionator and includes a description of all sources of sampling variance in the smooth fractionator design with newly developed predictors.

Low birth weight--is it associated with few and small glomeruli in normal subjects and NIDDM patients?

UNLABELLED: These studies were undertaken to ascertain if there is any association between low birth weight, and low kidney weight, few and/or small glomeruli, in kidneys from a control group and a group of non-insulin-dependent diabetic (NIDDM) patients. The background for this study comes from findings suggesting a correlation between low birth weight and the development of NIDDM and high blood pressure. Furthermore, Brenner has postulated that humans born with a low number of glomeruli, thereby having a low glomerular filtration surface area, have a greater tendency to develop high blood pressure. We examined 79 autopsy kidneys, with known weight from normal and NIDDM patients, which had previously been used for studies of glomerular number and volume. In the archives of the Danish midwives we were able to find birth weight for 26 NIDDM patients and an age- and sex-matched sample of 19 control persons. The kidney weight (g) ( CONTROL: 137 +/- 36; NIDDM: 150 +/- 38; 2p = 0.26), glomerular number (10(3)) (CONTROL: 670 +/- 176; NIDDM: 673 +/- 200; 2p = 0.95), glomerular volume (10(6) micron3) (CONTROL: 6.25 +/- 1.48; NIDDM: 5.71 +/- 1.74; 2p = 0.28) or birth weight (g) ( CONTROL: 3577 +/- 400; NIDDM: 3489 +/- 429; 2p = 0.49) were not different between the groups. There was no significant correlation between birth weight and glomerular number ( CONTROL: 2p = 0.80; r = 0.06 and NIDDM: 2p = 0.10; r = -0.33), glomerular volume ( CONTROL: 2p = 0.43; r = 0.19 and NIDDM: 2p = 0.78; r = 0.06) or kidney weight ( CONTROL: 2p = 0.56; r = 0.14 and NIDDM: 2p = 0.81; r = 0.05). Our results on a limited number of subjects in Denmark do not support the hypothesis that there is any association between low birth weight and low kidney weight or low birth weight and few and/or small glomeruli in NIDDM patients.

The number and size of glomeruli in long-term lithium-induced nephropathy in rats.

Chronic renal failure was induced in 10 Wistar rats using a lithium-containing (40 mmol/kg) diet from time of birth until an age of 55-65 weeks. Nine Wistar rats served as controls. The plasma lithium, the plasma urea, and the inulin clearance were measured, and one kidney was fixed by vascular perfusion with glutaraldehyde. The number of glomeruli was estimated stereologically by the fractionator method. The total number of glomeruli per kidney was 23.9 x 10(3) +/- 3.65 x 10(3) (+/- SD) in controls and 22.0 x 10(3) +/- 1.48 x 10(3) in the lithium-treated group, showing no statistically significant difference. The mean glomerular volume was also estimated using stereological methods. The number-weighted mean volume was reduced by 42% in the lithium-treated group, whereas the volume-weighted mean volume was unchanged. This can be attributed to the occurrence of many small glomeruli and a few very large glomeruli in the lithium-treated group. The many small glomeruli have in a previous study been shown to be atubular. The present study showed that the glomerular population is quite resistant to the deleterious effect of lithium; thus glomerular atrophy was seen, but no loss of glomeruli occurred.

The number of glomeruli in type 1 (insulin-dependent) and type 2 (non-insulin-dependent) diabetic patients.

The number of glomeruli per kidney in Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetic patients was estimated by an unbiased stereological method: the fractionator. No significant differences were observed between Type 1 and Type 2 diabetic patients without severe diabetic glomerulopathy and non-diabetic patients. Diabetic patients with proteinuria who were in the early stages of diabetic nephropathy also had a normal number of glomeruli. On the other hand, a subgroup classified as Type 1 diabetic patients with severe diabetic glomerulopathy had significantly less glomeruli compared with Type 1 diabetic patients with mild or no glomerulopathy. A probable explanation is that Type 1 diabetic patients lose glomeruli in relation to the progression of diabetic glomerulopathy. A more theoretical alternative is, however, that development of diabetic glomerulopathy is facilitated by a low number of glomeruli.

Glomerular number and size in relation to age, kidney weight, and body surface in normal man.

The number and size of glomeruli in normal, mature human kidneys were estimated by a direct and unbiased stereological method, the fractionator. The number was 617,000 on average, and the mean size 6.0 M microns3. Both glomerular number and size showed significant negative correlation to age and significant positive correlation to kidney weight. Apparently, humans loose glomeruli with age. Body surface area correlated positively to kidney weight and total glomerular volume but not to number of glomeruli. Body surface area correlates significantly with metabolic rate (Robertson and Reid, Lancet, 1: 940-943, 1952). Thus, intraspecies adaptation of kidney filtration capacity to the metabolic demand is performed by changing the size of glomeruli, i.e., the number of glomeruli in individuals of a given species is independent of the metabolic rate.

Glomerular volume in type 2 (noninsulin-dependent) diabetes estimated by a direct and unbiased stereologic method.

Glomerular volume was estimated in 20 type 2 diabetic patients (age 64 +/- 6 years, duration of diabetes 6 +/- 5 years) compared with 14 sex- and age-matched controls, as well as in a group of 11 very long-term type 1 diabetic patients (age 61 +/- 12 years, duration of diabetes 44 +/- 11 years). One whole autopsy kidney was obtained prospectively, and a known fraction (approximately equal to 1/140) was sampled systematically and embedded in plastic (JB-4 glycolmetacrylate), thereby essentially eliminating shrinkage. Sections 15-microns thick were stained with periodic acid-Schiff. Mean glomerular volume was estimated on a random sample of glomeruli using the disector method. Frequency of glomerular occlusion and mean volume of open glomeruli was estimated. Mean glomerular volume was not different between type 2 diabetic patients and controls (5.3 +/- 1.7 M mu3/1.73 m2 versus 5.3 +/- 1.9 M mu3/1.73 m2) nor was total glomerular volume or kidney weight. Frequency of glomerular occlusion was 4.8 +/- 5.7% in controls, 8.9 +/- 7.8% (p = 0.10) in type 2 patients, and 16.8% +/- 20.7 (p less than 0.05) in type 1 patients. In type 2 patients there was a correlation between frequency of glomerular occlusion and mean volume of open glomeruli (r = 0.44, p = 0.05), and the same tendency was seen in type 1 patients (r = 0.49, p = 0.12). By the present method the absolute level of glomerular volume was increased by at least a factor of two compared with previous studies. This illustrates the problems arising from shrinkage of tissue in paraffin and stresses the importance of using an unbiased stereological method. The lack of increase in total glomerular volume is in accordance with clinical findings of lack of glomerular hyperfiltration in type 2 patients, findings in contrast to those in type 1 diabetes. It is suggested that hyperfiltration per se is not the cause of glomerulopathy.

Unbiased estimation of particle number using sections--an historical perspective with special reference to the stereology of glomeruli.

Methods for estimating particle number may be based on at least three different principles. Two of them, isolation of particles and indirect counting, have been predominant until recently. The new methods based on section pairs (disectors) are unbiased and far more efficient. The three principles and their historical developments are described, emphasizing that the newly developed principles have old roots, which were forgotten until recently. It is concluded, that 'learned societies' combined with individual enthusiasm are material for the spread and development of new ideas.