Efficacy of iliopsoas plane block for patients undergoing hip arthroscopy: a prospective, triple-blind, randomized, placebo-controlled trial

BACKGROUND

Intraoperative stretching of the hip joint capsule often generates severe pain during the first 3 hours after hip arthroscopy. The short-lived severe pain mandates high opioid consumption, which may result in adverse events and delay recovery. The femoral nerve nociceptors are located anteriorly in the hip joint capsule. A femoral nerve block reduces pain and opioid demand after hip arthroscopy. It impedes, however, ambulation and home discharge after outpatient surgery. The iliopsoas plane block selectively anesthetizes the femoral sensory nerve branches innervating the hip joint capsule without compromising ambulation. We aimed to assess reduction of opioid consumption after iliopsoas plane block during the short-lived painful postsurgical period of time after hip arthroscopy.

METHODS

In a randomized, triple-blind trial, 50 patients scheduled for hip arthroscopy in general anesthesia were allocated to active or placebo iliopsoas plane block. The primary outcome was opioid consumption during the first three postoperative hours in the postanesthesia care unit. Secondary outcomes included pain, nausea, and ability to ambulate.

RESULTS

Forty-nine patients were analyzed for the primary outcome. The mean 3-hour intravenous morphine equivalent consumption in the iliopsoas plane block group was 10.4 mg vs 23.8 mg in the placebo group (p<0.001). No intergroup differences were observed for the secondary outcomes during the postoperative follow-up.

CONCLUSION

An iliopsoas plane block reduces opioid consumption after hip arthroscopy. The reduction of opioid consumption during the clinically relevant 3-hour postsurgical period of time was larger than 50% for active versus placebo iliopsoas plane block in this randomized, triple-blind trial.

Standardizing nomenclature in regional anesthesia: an ASRA-ESRA Delphi consensus study of upper and lower limb nerve blocks

BACKGROUND

Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks.

METHODS

We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%-74% agreement.

RESULTS

A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research.

CONCLUSIONS

We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

Anatomical considerations for obturator nerve block with fascia iliaca compartment block

This report reviews the topographical and functional anatomy relevant for assessing whether or not the obturator nerve (ON) can be anesthetized using a fascia iliaca compartment (FIC) block. The ON does not cross the FIC. This means that the ON would only be blocked by an FIC block if the injectate spreads to the ON outside of the FIC. Such a phenomena would require the creation of one or more artificial passageways to the ON in the retro-psoas compartment or the retroperitoneal compartment by disrupting the normal anatomical integrity of the FI. Due to this requirement for an artificial pathway, an FIC block probably does not block the ON.

Transmuscular quadratus lumborum block reduces opioid consumption and prolongs time to first opioid demand after laparoscopic nephrectomy

BACKGROUND

Robotic and hand-assisted laparoscopic nephrectomies are often associated with moderate to severe postoperative pain. The aim of the current study was to investigate the analgesic efficacy of the transmuscular quadratus lumborum (TQL) block for patients undergoing robotic or hand-assisted laparoscopic nephrectomy.

METHODS

Fifty patients were included in this single-center study. All patients were scheduled for elective hand-assisted or robotic laparoscopic nephrectomy under general anesthesia. Preoperatively, patients were randomly allocated to TQL block bilaterally with ropivacaine 60 mL 0.375% or 60 mL saline and all patients received standard multimodal analgesia and intravenous patient-controlled analgesia. Primary outcome was postoperative oral morphine equivalent (OME) consumption 0-12 hours. Secondary outcomes were postoperative OME consumption up to 24 hours, pain scores, time to first opioid, nausea/vomiting, time to first ambulation and hospital length of stay (LOS).

RESULTS

Mean (95% CI) OME consumption was significantly lower in the intervention group at 12 hours after surgery 50 (28.5 to 71.5) mg versus control 87.5 (62.7 to 112.3) mg, p=0.02. At 24 hours, 69.4 (43.2 to 95.5) mg versus 127 (96.7 to 158.6) mg, p<0.01. Time to first opioid was significantly prolonged in the intervention group median (IQR) 4.4 (2.8-17.6) hours compared with 0.3 (0.1-1.0) hours in the control group, p<0.001. No significant intergroup differences were recorded for time to first ambulation, pain scores, nausea/vomiting nor for LOS.

CONCLUSION

Preoperative bilateral TQL block significantly reduced postoperative opioid consumption by 43% and significantly prolonged time to first opioid.

TRIAL REGISTRATION NUMBER

NCT03571490.

Transmuscular quadratus lumborum block for total laparoscopic hysterectomy: a double-blind, randomized, placebo-controlled trial

BACKGROUND

The population of patients scheduled for total laparoscopic hysterectomy at our surgical center is heterogeneous concerning a multitude of demographic variables such as age, collateral surgery and malign or benign pathogenesis. A common denominator is moderate to severe postoperative pain and a substantial opioid consumption. A recent procedure specific postoperative pain management (PROSPECT) review found no gain from the regional techniques included. The transmuscular quadratus lumborum (TQL) block has shown promising results in recent trials for other types of surgery. The aim of the current study was to investigate the analgesic efficacy of the ultrasound-guided TQL block for total laparoscopic hysterectomy.

METHODS

We enrolled 70 patients and randomly allocated participants to preoperative bilateral ultrasound-guided TQL block with either 60 mL 0.375% ropivacaine or 60 mL isotonic saline. Preoperatively, all patients received the TQL block (active or placebo) as well as a standardized multimodal analgesic regimen consisting of oral paracetamol, ibuprofen and dexamethasone. Intraoperatively, intravenous sufentanil 0.2 µg/kg was administered 30 min prior to emergence.

PRIMARY OUTCOME

Opioid consumption during the first 12 postoperative hours.

SECONDARY OUTCOMES

Pain scores, times to first opioid demand and first ambulation, nausea and vomiting, and total opioid consumption during the first 24 postoperative hours.

RESULTS

No significant intergroup differences were observed for any outcome. Mean (SD) oral morphine equivalent consumption the first 12 postoperative hours was 58.4 mg (48.3) vs 62.9 mg (48.5), p=0.70, for group ropivacaine versus group saline.

CONCLUSION

Preoperative bilateral ultrasound-guided TQL block did not reduce opioid consumption after total laparoscopic hysterectomy.

TRIAL REGISTRATION NUMBERS

NCT03650998, EudraCT (2017-004593-34).

Anesthesia of the anterior femoral cutaneous nerves for total knee arthroplasty incision: randomized volunteer trial

BACKGROUND AND OBJECTIVES

For pain relief after total knee arthroplasty (TKA), an injection at the midthigh level may produce analgesia inferior to that of a femoral nerve block as the anterior femoral cutaneous nerves (intermediate femoral cutaneous nerve (IFCN) and medial femoral cutaneous nerve (MFCN)) are not anesthetized. The IFCN can be selectively anesthetized in the subcutaneous tissue above the sartorius muscle and the MFCN by an injection in the proximal part of the femoral triangle (FT). The primary aim was to investigate the area of cutaneous anesthesia in relation to the surgical incision for TKA and anteromedial knee area after intermediate femoral cutaneous nerve blockade (IFCNB) in combination with an injection in the proximal or distal part of the FT (proximal vs distal femoral triangle block (FTB)).

METHODS

The study was carried out as two separate investigations: first, dissection of nine cadaver sides to verify a technique for IFCNB; second, a volunteer study with 40 healthy volunteers. The surgical midline incision for TKA was drawn bilaterally. All volunteers received an active distal FTB combined with a placebo proximal FTB on one side and vice versa on the other side. All volunteers were randomized to an active IFCNB on one side and placebo IFCNB on the contralateral side.

RESULTS

Identification of IFCN was successful in all cadaver sides. Fifteen out of 20 volunteers had complete anesthesia of the incision line after IFCNB combined with proximal FTB, which was significantly higher compared with proximal FTB alone and with distal FTB+IFCNB. A gap at the anteromedial knee area was present in 2/20 volunteers with proximal FTB compared with 17/20 with distal FTB when all volunteers had active IFCNB.

CONCLUSION

Ultrasound-guided blockade of the IFCN and MFCN anesthetize the surgical midline incision and the anteromedial area of the knee relevant for TKA. In contrast, an injection at the midthigh level produces insufficient cutaneous anesthesia not covering the areas of interest.

TRIAL REGISTRATION NUMBER

EudraCT: 2018-004986-15.

Ultrasound-guided transmuscular quadratus lumborum block for elective cesarean section significantly reduces postoperative opioid consumption and prolongs time to first opioid request: a double-blind randomized trial

BACKGROUND

Elective cesarean section (ECS) can cause moderate to severe pain that often requires opioid administration. To enhance maternal recovery, and promote mother and baby interaction, it is important to reduce postoperative pain and opioid consumption. Various regional anesthesia techniques have been implemented to improve postoperative pain management following ECS. This study aimed to investigate the efficacy of bilateral ultrasound-guided transmuscular quadratus lumborum (TQL) block on reducing postoperative opioid consumption following ECS.

METHODS

A randomized double-blind trial with concealed allocation was conducted in 72 parturients who received bilateral TQL block with either 30 mL ropivacaine 0.375% or saline. TQL block injectate was deposited in the interfascial plane between the quadratus lumborum and psoas major muscles, posterior to the transversalis fascia. Primary outcome was opioid consumption, which was recorded electronically. Pain scores and time to first opioid request were also evaluated.

RESULTS

Opioid consumption (oral morphine equivalents, OME) was significantly reduced in group ropivacaine (GRO) in the first 24 hours compared with group saline (65 mg OME vs 94 mg OME) with a mean difference of 29 mg OME; 95% CI 3 to 55, p<0.03. Time to first opioid request was significantly prolonged in GRO, p<0.003. Numerical rating scale pain scores were significantly lower in GRO in the first 6 hours after surgery, p<0.03.

CONCLUSIONS

Bilateral TQL block significantly reduced 24 hours' opioid consumption. Further, we observed significant prolongation in time to first opioid, and significant reduction of pain during the first 6 postoperative hours.

Randomized trial of ultrasound-guided superior cluneal nerve block

BACKGROUND AND OBJECTIVES

The superior cluneal nerves originate from the dorsal rami of primarily the upper lumbar spinal nerves. The nerves cross the iliac spine to innervate the skin and subcutaneous tissue over the gluteal region. The nerves extend as far as the greater trochanter and the area of innervation may overlap anterolaterally with the iliohypogastric and the lateral femoral cutaneous (LFC) nerves. A selective ultrasound-guided nerve block technique of the superior cluneal nerves does not exist. A reliable nerve block technique may have application in the management of postoperative pain after hip surgery as well as other clinical conditions, for example, chronic lower back pain. In the present study, the primary aim was to describe a novel ultrasound-guided superior cluneal nerve block technique and to map the area of cutaneous anesthesia and its coverage of the hip surgery incisions.

METHODS

The study was carried out as two separate investigations. First, dissection of 12 cadaver sides was conducted in order to test a novel superior cluneal nerve block technique. Second, this nerve block technique was applied in a randomized trial of 20 healthy volunteers. Initially, the LFC, the subcostal and the iliohypogastric nerves were blocked bilaterally. A transversalis fascia plane (TFP) block technique was used to block the iliohypogastric nerve. Subsequently, randomized, blinded superior cluneal nerve blocks were conducted with active block on one side and placebo block contralaterally.

RESULTS

Successful anesthesia after the superior cluneal nerve block was achieved in 18 of 20 active sides (90%). The area of anesthesia after all successful superior cluneal nerve blocks was adjacent and posterior to the area anesthetized by the combined TFP and subcostal nerve blocks. The addition of the superior cluneal nerve block significantly increased the anesthetic coverage of the various types of hip surgery incisions.

CONCLUSION

The novel ultrasound-guided nerve block technique reliably anesthetizes the superior cluneal nerves. It anesthetizes the skin posterior to the area innervated by the iliohypogastric and subcostal nerves. It improves the anesthetic coverage of incisions used for hip surgery. Among potential indications, this new nerve block may improve postoperative analgesia after hip surgery and may be useful as a diagnostic block for various chronic pain conditions. Clinical trials are mandated.

TRIAL REGISTRATION NUMBER

EudraCT, 2016-004541-82.

An Obturator Nerve Block does not Alleviate Postoperative Pain after Total Hip Arthroplasty: a Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

A substantial group of patients suffer from moderate to severe pain following elective total hip arthroplasty (THA). Due to the complex innervation of the hip, peripheral nerve block techniques can be challenging and are not widely used. Since the obturator nerve innervates both the anteromedial part of the joint capsule as well as intra-articular nociceptors, we hypothesized that an obturator nerve block (ONB) would decrease the opioid consumption after THA.

METHODS

Sixty-two patients were randomized to receive ONB or placebo (PCB) after primary THA in spinal anesthesia. Primary outcome measure was opioid consumption during the first 12 postoperative hours. Secondary outcome measures included postoperative pain score, nausea score and ability to ambulate.

RESULTS

Sixty patients were included in the analysis. Mean (SD) opioid consumption during the first 12 postoperative hours was 39.9 (22.3) mg peroral morphine equivalents (PME) in the ONB group and 40.5 (30.5) mg PME in the PCB group (p=0.93). No difference in level of pain or nausea was found between the groups. Paralysis of the hip adductor muscles in the ONB group reduced the control of the operated lower extremity compared with the PCB group (p=0.026). This did, however, not affect the subjects' ability to ambulate.

CONCLUSIONS

A significant reduction in postoperative opioid consumption was not found for active versus PCB ONB after THA.

TRIAL REGISTRATION NUMBER

NCT03064165 and 2017-000068-14.

Cutaneous anaesthesia of hip surgery incisions with iliohypogastric and subcostal nerve blockade: A randomised trial

BACKGROUND

Cutaneous nerve blockade may improve analgesia after hip surgery. Anaesthesia after the lateral femoral cutaneous (LFC) nerve block is too distal for complete coverage of most hip surgery incisions, which requires additional anaesthesia of the adjacent, proximal area. The transversalis fascia plane (TFP) block potentially anaesthetises the iliohypogastric and subcostal nerves. The primary aim of the present study was to investigate, if the TFP block provides cutaneous anaesthesia adjacent to the LFC nerve block.

METHODS

Active vs placebo TFP blocks were compared in a paired randomised controlled trial (RCT) in 20 volunteers, who all had bilateral LFC nerve blocks. The day preceding the RCT, the area anaesthetised by a novel selective ultrasound guided subcostal nerve block was identified bilaterally in order to assess the contribution of the subcostal nerve to the area anaesthesia by the TFP block.

RESULTS

Anaesthesia of the lateral hip region after TFP block was 80%. The cutaneous anaesthesia after active TFP block was in continuity with the LFC nerve block in 65%. Combined TFP and LFC nerve blockade significantly increased the coverage of hip surgery incisions compared to LFC nerve block alone. The success rate of blocking the subcostal nerve was 50% with the TFP block.

CONCLUSION

The TFP block anaesthetises the skin proximal to the LFC nerve block by anaesthetising the iliohypogastric and subcostal nerves. TFP block as a supplement to LFC nerve block improves the coverage of the proximal surgical incisions used for hip surgery.

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.

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.

[Prehospital ultrasound]

Danish anaesthesiologists use ultrasound (US) to examine and treat acutely ill or traumatized patients in the emergency room, operating theatre and intensive care unit. They are also involved in pre-hospital care where US may theoretically be beneficial for both diagnostic and therapeutic purposes. The literature concerning the potential use of emergency US in the pre-hospital setting is evaluated. Evidence from both Europe and the USA indicates that pre-hospital US improves diagnosis and visitation of acutely ill or traumatized patients.

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?

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.

The new stereological tools: disector, fractionator, nucleator and point sampled intercepts and their use in pathological research and diagnosis

The new stereological methods for correct and efficient sampling and sizing of cells and other particles are reviewed. There is a hierarchy of methods starting from the simplest where even the microscopic magnification may be unknown to the most complex where typically both section thickness and the magnification must be known. Optical sections in suitably modified microscopes can be used to improve the ease and speed with which even the most demanding of these methods are performed. The methods are illustrated by practical examples of applications to a wide range of histological entities including synapses, neurons and cancer cells, glomerular corpuscles and ovarian follicles.

Some new, simple and efficient stereological methods and their use in pathological research and diagnosis

Stereology is a set of simple and efficient methods for quantitation of three-dimensional microscopic structures which is specifically tuned to provide reliable data from sections. Within the last few years, a number of new methods has been developed which are of special interest to pathologists. Methods for estimating the volume, surface area and length of any structure are described in this review. The principles on which stereology is based and the necessary sampling procedures are described and illustrated with examples. The necessary equipment, the measurements, and the calculations are invariably simple and easy.