bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling Determinants of Participation, Number of Trips and Site Choice for Outdoor Recreation in Protected Areas
Authors: Romano Donato , Scarpa Riccardo , Spalatro Fiorenza , Viganò Laura
Published: September 2010

This is a study on demand for outdoor recreation in a national system of environmentally protected areas. The exercise is based on a nationwide survey carried out in 1996 from a stratified random sample of 5,574 Italian households. Data on socio‐economic characteristics and recreational choice behaviour of respondents were collected and this information was supplemented by a second data‐base containing information on 193 Italian EPAs in order to characterise the different outdoor destinations on the basis of their recreational attributes. These data sets are used here to model choices of outdoor recreation within environmentally protected areas, using a sequence of three different models: (i) a dichotomous choice logit model for the probability of participation conditional on household covariates; (ii) a count data Poisson model to estimate the household's expected number of trips per year; (iii) a conditional logit model to estimate the probability of site selection conditional on site attributes. We report the estimated per‐trip welfare changes derivable from an actual policy proposal which would extend the area under environmental protection by ten per cent.
The Distributional Impact of Direct Payments on Irish Farm Incomes
Authors: Keeney Mary
Published: September 2010

The objective of this paper is to analyse the distributional effects of the different income components of Irish farm income with a Gini comparison method and by disaggregating the overall Gini coefficient of income inequality by income source. Using individual farm data for 1992 and 1996, the impact on farm income distribution of the MacSharry CAP reform is assessed. In addition, the change in the Gini coefficient between these years is decomposed into the changes in the within‐source distribution of each income stream and the share of each income stream. The favourable movement in the Gini coefficient is found to be due to the introduction of direct payments, which target less well‐off farmers. Market income remains the single largest influence on deciding the income ranking of a farm while contributing less to total income than before.
Effects of Non‐Farm Employment on Rural Income Inequality in Developing Countries: An Investment Perspective
Authors: Reardon Thomas , Taylor J. Edward , Stamoulis Kostas , Lanjouw Peter , Balisacan Arsenio
Published: September 2010

This paper makes several points based on a review of household survey evidence from Africa, Asia and Latin America. (i) In contrast to conventional wisdom, the evidence is very mixed as to the effect of non‐farm employment on rural income inequality. The non‐farm employment and microenterprise programmes now in vogue will not necessarily resolve rural income inequality problems and attendant social tensions nor automatically benefit the poor. (ii) Policymakers should be worried by substantial evidence of poor people's inability to overcome important entry barriers to many non‐farm activities. (iii) The main determinants of unequal access to non‐farm activities are the distribution of capacity to make investments in non‐farm assets and the relative scarcity of low capital entry barrier activities. Therefore, it is crucial for public investments and policy to favour an increase in the access of the poor to assets that allow them to overcome non‐farm employment entry barriers, (iv) It would be an error to assume that one can address asset‐poverty and inequality in the non‐farm sector without addressing farm‐side problems and vice versa.
The Determinants of Rural Livelihood Diversification in Developing Countries
Authors: Ellis Frank
Published: September 2010

The diversity of rural livelihoods in low income developing countries is receiving increased attention in discussions about rural poverty reduction. This paper explores just one facet of livelihood diversity, namely the reasons for households to adopt multiple livelihood strategies. The distinction is made between diversification of necessity and diversification by choice. Six determinants of diversification are considered in the light of that distinction, and these are seasonality, risk, labour markets, credit markets, asset strategies, and coping strategies. The paper concludes that under the precarious conditions that characterise rural survival in many low income countries, diversification has positive attributes for livelihood security that outweigh negative connotations it may possess. Policy should facilitate rather than inhibit diversity. Diverse rural livelihoods are less vulnerable than undiversified ones.
Measuring Perceived Performance of the Food System and Consumer Food‐Related Welfare
Authors: Henson Spencer , Traill Bruce
Published: September 2010

The paper explores the use of multi‐item summated scales for the measurement of the perceived performance of the food system and of an index to measure consumer food‐related welfare. Scales are developed that encompass a range of factors that influence the welfare consumers derive from food, including food safety, convenience, ethical issues, health and nutrition, taste and cost. These scales are applied to a national sample of food consumers in the United States and the United Kingdom. On the basis of the survey results, there is evidence that the scales are both reliable and valid measures of the perceived performance of the food system in both countries. An index of consumer food‐related welfare is developed that weights the various performance measures according to respondents' measure of importance. Survey respondents judge that the food system is not performing particularly well in either country. Although more work is required on the use of summated multi‐item scales for this purpose, the results suggest that this is a potentially useful approach that provides relevant information on the impact of different elements of the food system on consumer welfare.
Marketing Co‐operatives: An Incomplete Contracting Perspective
Authors: Hendrikse George W. J. , Veerman Cees P.
Published: September 2010

Marketing co‐operatives (MCs) are analysed from an incomplete contracting perspective. The requirement of the domination of control by the members of an MC is a threat to the survival of an MC in markets where the level of asset specificity at the processing stage of production is increasing. However, an MC may remain an efficient governance structure when the increasing level of asset specificity is compensated for by a sufficient increase in the extent of product differentiation.
An Investigation of Policy Administrative Costs Using Panel Data for the English Environmentally Sensitive Areas
Authors: Falconer Katherine , Dupraz Pierre , Whitby Martin
Published: September 2010

This paper explores transactions costs in the context of agri‐environmental policy schemes based on management agreements. While transactions costs encompass a wide range of organisational costs, the focus here is on the public‐sector administrative costs of policy implementation. Empirical administrative cost functions were estimated to investigate the factors affecting the magnitude of such costs, using panel data spanning five years for the 22 English Environmentally Sensitive Areas. The extent of participation appears to be important in explaining administrative cost variability across areas. The data suggested the existence of size economics with regard to the numbers of agreements made in any one ESA, and a significant effect of scheme experience in exerting downwards‐pressure on administrative costs. Policy budgeting and evaluation should take into account the non‐trivial costs of organisation, particularly if agri‐environmental schemes based on the procurement of conservation goods through management agreements are to be extended in future.
Intergenerational Succession on Israeli Family Farms
Authors: Kimhi Ayal , Nachlieli Noga
Published: September 2010

Using a binary‐choice analysis, we study the likelihood of intra family intergenerational succession on Israeli family farms. This provides policy‐relevant information on the long‐run survival probabilities of these farms in a period of increased vulnerability of family farms. We compare two definitions of succession, one based on an official declaration of a succeeding child, and another which is more operational, based on the existence of an adult child who works on the farm alongside the parents. We also validate the probit results by comparing them to those of a more robust semi‐nonparametric method. We identify a number of family and farm attributes whose effects are statistically significant and consistent with economic theory based on the notion of an economic surplus resulting from intra‐family succession and on the notion of bargaining between the generations.
Evaluating alternative “countermeasures” against food contamination resulting from nuclear accidents
Authors: Hanley Nick , Salt Carol A. , Wilson Mike , Culligan‐Dunsmore Meara
Published: September 2010

Nuclear accidents such as Chernobyl have far reaching impacts on ecological systems. Likewise they have major implications for agricultural systems, since crops and livestock can become contaminated and rendered unfit for human consumption. A range of “countermeasures” exists, however, which can mitigate these impacts and allow food products to be saved. The CESER project has been concerned with the development of a system to assess the environmental side‐effects of such countermeasures. Estimates of the economic costs of these environmental side‐effects have been made for a number of case study sites in the UK, using environmental models and an original contingent valuation study. Estimates of farm level (private) costs are also included.
Dynamic Area Allocation and Economies of Scale and Scope
Authors: Lansink Alfons Oude , Stefanou Spiro
Published: September 2010

This article applies the adjustment cost framework to the case of area allocation by simultaneously determining the levels of input demand and output supply. Dynamic measures of economies of scale and scope are defined for output‐specific areas. An application to a rotating sample of Dutch cash crops reveals that farmers have a strong incentive for specialisation, but that large adjustment costs for area allocation resulting in small adjustments toward the optimal level prevent them from doing so.
Asian Agricultural Productivity and Convergence
Authors: Suhariyanto Kecuk , Thirtle Colin
Published: September 2010

This paper measures agricultural total factor productivity (TFP), for eighteen Asian countries, from 1965 to 1996. TFP is measured by calculating the Malmquist index with respect to the sequential frontier, which is appropriate when the cross section is relatively small. The results show that half the countries have experienced negative productivity growth, due to losses in technical efficiency combined with stagnation in technological progress. Both cross‐section and time series tests show that there is no evidence of convergence in agricultural productivity for these countries. The less productive countries are falling further behind, rather than catching up. Finally, comparisons with Africa show that although Asia has had faster TFP growth than Africa, three of the five African regions (East, Central and Southern) have grown faster than any of the Asian regions.
Who Pays More for Food?
Authors: Stewart Hayden , Blisard Noel
Published: September 2010

Building on research with unit values, we demonstrate how a household's per serving and total vegetable expenditures depend on both the characteristics of the household and on its location. The lower a household's income, for example, the lower is vegetable spending, all else constant. However, households living in communities with high real estate prices, or with a high incidence of poverty, among other things, tend to pay more. Simulations further illustrate the effect that a community's characteristics can have on a household's vegetable spending, if the household lives in each of 10 cities in the United States.
Assessing the Impact of the ‘Decoupling’ Reform of the Common Agricultural Policy on Irish Farmers’ Off‐farm Labour Market Participation Decisions
Authors: Hennessy Thia C. , Rehman Tahir
Published: September 2010

This paper assesses the impact of the ‘decoupling’ reform of the Common Agricultural Policy on the labour allocation decisions of Irish farmers. The agricultural household decision‐making model provides the conceptual and theoretical framework to examine the interaction between government subsidies and farmers’ time allocation decisions. The relationship postulated is that ‘decoupling’ of agricultural support from production would probably result in a decline in the return to farm labour but it would also lead to an increase in household wealth. The effect of these factors on how farmers allocate their time is tested empirically using labour participation and labour supply models. The models developed are sufficiently general for application elsewhere. The main findings for the Irish situation are that the decoupling of direct payments is likely to increase the probability of farmers participating in the off‐farm employment market and that the amount of time allocated to off‐farm work will increase.
Technology Adoption and Pest Control Strategies Among UK Cereal Farmers: Evidence from Parametric and Nonparametric Count Data Models
Authors: Sharma Abhijit , Bailey Alastair , Fraser Iain
Published: September 2010

This paper examines the intensity of technology adoption and integrated pest management strategies employed by UK farmers, using both parametric and nonparametric methods. We employ a unique survey dataset collected from UK cereal farmers to assess the determinants of technology adoption in relation to pest management. Our preferred model specification is nonparametric, with models estimated yielding broadly similar results, with some important qualitative differences. All models indicate that total area farmed is positively related to the number of technologies adopted, whereas the number of years of experience of the farmer is negatively related. We also find evidence with our nonparametric specification of significant statistical differences for number of adoptions by region across the UK.
Influence of Attachment Systems on Load Transfer of an Implant‐Assisted Maxillary Overdenture
Authors: Fanuscu Mete I. , Caputo Angelo A.
Published: September 2010

Purpose:
This photoelastic study compared the load transfer characteristics of 2 retention mechanisms in an implant‐assisted overdenture prosthesis.

Materials and Methods:
Four implants were incorporated into a photoelastic model of a moderately resorbed edentulous human maxilla. Two retention mechanisms were studied by changing components on the same model and the palateless overdenture. The retention mechanisms studied were bar splint with anterior clip and distal resilient attachments, and solitary ball/O‐ring attachments. Loads, ranging from 1.4 to 14.4 kg, were applied to the palatal incline of central incisors and buccal incline of premolars with and without balancing contacts. Stresses developed around all the implants under each loading condition were photographed in the field of a circular polariscope.

Results:
With both retention mechanisms, protrusive and laterotrusive loads without balancing contacts caused instability of the overdenture, producing minimal stress around the implants in the supporting structure. High intensity stresses indicating intrusion of the posterior implants were noted when the bar/distal resilient attachment overdenture had balancing contacts for protrusive and laterotrusive loads. The posterior implants of ball/O‐ring attachment overdenture exhibited high intensity stresses indicating not only intrusion, but also bending, when the occlusion was balanced.

Conclusions:
Balanced occlusion was required in both retention mechanisms for stability of the implant‐assisted overdenture when clinically acceptable loads were applied. The protrusive and laterotrusive loads were not distributed equitably in either mechanism, since highest stresses occurred at the posterior implants.
Retention Characteristics of Attachment Systems for Implant Overdentures
Authors: Chung Kwok‐Hung , Chung Cho‐Yao , Cagna David R. , Cronin Robert J.
Published: September 2010

Purpose:
The aim of this study was to compare the retention characteristics of various overdenture attachment systems commonly used to retain overdentures to dental implants.

Materials and Methods:
An edentulous mandibular model was constructed incorporating 2 parallel 4.0 mm × 13 mm Branemark implants placed in the canine regions. Attachments were embedded in a metal‐reinforced experimental overdenture designed to be dislodged from the model by a universal testing machine. Tensile dislodging force was applied to the overdenture at a cross‐head speed of 50 mm/min. Five overdentures were constructed for each of the attachment systems. The attachments evaluated were the Hader bar & metal clip, Locator LR pink, Locator LR white, Spheroflex ball, Shiner magnet, Maxi magnet, Magnedisc magnet, ERA white, and ERA gray. Each apparatus was tested with 5 specimens per attachment system. Peak load‐to‐dislodgement was measured. Analysis of variance and Scheffé multiple comparison tests were applied to the data with α≤ 0.05 level of significance.

Results:
Peak load‐to‐dislodgement for all attachment systems ranged from 3.68 ± 1.32 N to 35.24 ± 1.99 N. Strain‐at‐dislodgement, calculated from stress‐strain curves, ranged from 0.78 ± 0.20% to 2.78 ± 0.5%. The ERA gray attachment demonstrated the greatest retention, with a peak load‐to‐dislodgement of 35.24 ± 1.99 N, and a relatively low strain‐at‐dislodgement of 1.64 ± 0.09%. Less retention was recorded for the Locator LR white, Spheroflex ball, Hader bar & metal clip, and ERA white systems. The Locator LR pink attachment demonstrated still less retention with a load‐to‐dislodgement of 12.33 ± 1.28 N. Significantly high strain‐at‐dislodgement was recorded for the Hader bar & metal clip and Locator nylon attachment systems. The lowest dislodging loads and strains were recorded for the Shiner magnet, Maxi magnet, and Magnedisc magnet attachments.

Conclusions:
Results suggest that the attachment systems evaluated may be grouped into high (ERA gray), medium (Locator LR white, Spheroflex ball, Hader bar & metal clip, ERA white), low (Locator LR pink), and very low (Shiner magnet, Maxi magnet, Magnedisc magnet) retention characteristics.
Pain Processing: Paradoxes and Predictions
Authors: Martin William J.
Published: September 2010

Abstract:During the last 25 years, there have been substantial advances in our understanding of the physiology and pathophysiology of pain. The development of animal models that more closely mimic clinical pain in humans has helped elucidate the putative mechanisms by which chronic pain develops and is maintained. However, our increased understanding of the neurobiology of pain has not translated into breakthrough treatments for pain management. As such, chronic pain is still primarily managed by drugs whose primary indication does not include pain (eg, antidepressants, anticonvulsants, antiarrhythmics, local anesthetics). These adjuvant analgesics have come into favor despite the fact that the mechanisms through which these drugs provide pain relief remain either largely unknown or are not selective for a single target. Moreover, the efficacy of adjuvant analgesics in animal models of pain is often validated only after case studies or clinical trials have been reported. This retrospective validation of “novel” analgesics in animal models of pain raises a question of the predictive validity of these models. This article reviews the use of several adjuvant and standard analgesics currently used to treat difficult‐to‐manage pain. What can these drugs teach us about the development of novel pain medicines? Within this context, the use of animal models of pain to predict analgesic efficacy in clinical pain conditions is considered.
Epidemiology, Pathophysiology, and Management of Complex Regional Pain Syndrome
Authors: Pappagallo Marco , Rosenberg Andrew D.
Published: September 2010

Abstract: Complex regional pain syndromes (CRPS) are challenging neuropathic pain states quite difficult to comprehend and treat. Although not yet fully understood, advances are being made in the knowledge of the mechanisms involved with CRPS. Patients often present with incapacitating pain and loss of function. Patients suffering from these disorders need to have treatment plans tailored to their individual problems. A comprehensive diagnostic evaluation and early and aggressive therapeutic interventions are imperative. The therapeutic approach often calls for a combination of treatments. Medications such as antiepileptics, opioids, antidepressants, and topical agents along with a rehabilitation medicine program can help a major portion of patients suffering from these disorders. Implantable devices can aid those patients with CRPS. While progress is being made in treating patients with CRPS, it is important to remember that the goals of care are always to: 1) perform a comprehensive diagnostic evaluation, 2) be prompt and aggressive in treatment interventions, 3) assess and reassess the patient's clinical and psychological status, 4) be consistently supportive, and 5) strive for the maximal amount of pain relief and functional improvement. In this review article, the current knowledge of the epidemiology, pathophysiology, diagnostic, and treatment methodologies of CRPS are discussed to provide the pain practitioner with essential and up‐to‐date guidelines for the management of CRPS.
Vertebroplasty
Authors: Anderson Susan R.
Published: September 2010

Abstract: Vertebroplasty is the percutaneous placement of polymethylmethacrylate (PMMA) into vertebral compression fractures for relief of pain. Polymethylmethacrylate is the cement used by orthopedic surgeons for rapid stable fixation of prosthetics in living bone. While the exact mechanism of pain relief is unknown, it is believed that the delivery of the PMMA into the fracture stabilizes the vertebral body, obtaining an analgesic effect. Vertebroplasty is an outpatient procedure that is performed with the aid of fluoroscopy. It has a high benefit/risk ratio with high success rates in comparison to extremely low complication rates. These patients consist of elderly osteoporotic patients that often times have underlying medical conditions or younger patients suffering from steroid or metastatic induced compression fractures. These patients are considered to be poor surgical candidates. In the past, this patient population has been relegated to epidural steroid injections, epidural catheters, or time contingent narcotics to control the pain. These conservative measures often lead to a patient with decreased activities of daily living and uncontrolled pain. Vertebroplasty provides a safe procedure that allows for long‐term pain relief, decreased use of medication, and increased activities of daily living. This article is a review of the history, indications, contraindications, and key outcome studies. The technique is described along with complications, preprocedural care, and postprocedural care.
Anesthesia (1)
Authors: Maneksha Farrokh R. , Mirza Himayun , Poppers Paul J.
Published: September 2010

Complex regional pain syndrome (CRPS) with resistance to local anesthetic block: a case report. (State University of New York at Stony Brook, Stony Brook, NY) J Clin Anesth 2000;12:67–71.

A case of complex regional pain syndrome (CRPS) Type 1 in a 12‐year‐old girl is presented. The patient did not respond to the usual therapeutic modalities used to treat CRPS including physical therapy, lumbar sympathetic block, epidural local anesthetic block, intravenous lidocaine infusion, or other oral medications. Of note is the fact that during epidural block the patient demonstrated a resistance to local anesthetic neural blockade in the area of the body involved with the pain problem. The mechanism of this resistance could be related to the changes in the dorsal horn cells of the spinal cord, secondary to activation of N‐methyl‐D‐aspartate receptors, which may play a role in the pathophysiology of this pain syndrome.
Pharmacology of Peripheral Analgesia
Authors: Ness Timothy J.
Published: September 2010

Abstract:Pain may begin in the periphery with activation of nociceptor transducers. The present article reviews the pharmacology of drug action at the level of the primary afferent by discussing the following: [1] agents which block transduction processes (vanilloids, sodium ion channel blockers, antiserotonergic agents, antipurinergic agents); [2] agents inhibiting the transducer site (opioids, cannabinoids, alpha adrenergic agents); [3] agents blocking transducer‐based modulation processes (anti‐inflammatories, antikinin agents, antitachykinins); and [4] agents which block primary afferent‐related modification processes (antineurotrophins). There is a clear role for many of these agents in the treatment of inflammatory pain and they have potential benefits for neuropathic pain with peripheral triggers.
Anesthesia (15)
Authors: Okunda Yasuhisa , Okuda Keiko , Shinohara Masayuki , Kitajima Toshimitsu
Published: September 2010

Use of computed tomography for maxillary nerve block in the treatment of trigeminal neuralgia. (Dokkyo University School of Medicine, Mibu, Tochigi, Japan) Reg Anesth Pain Med 2000;25:417–419.

A report of a 90‐year‐old woman who had a 30‐year history of episodic pain in her right maxillary region is presented. An attempt to block the nerve with classic technique was made, but eliciting paresthesia could not identify the nerve. In addition, bleeding was noted after repeated attempts. To minimize complications and confirm the correct position of the needle tip, the block was planned with a suprazygomatic approach using computed tomography (CT) guidance. The needle was inserted without paresthesia. The CT scan showed the needle tip was placed at the entrance of the pterygopalatine fossa and the distribution of contrast medium spread appropriately around the pterygopalatine fossa. After confirming the clinical effect and lack of complications of the block using the local anesthetic, 0.5 mL of 7% phenol was injected. The technique resulted in complete sensory loss in the area innervated by the maxillary nerve and did so without complications.

Comment by Andrew D. Rosenberg, MD.

This is an interesting article in which the authors describe their technique for treating trigeminal neuralgia. The authors were faced with a significant problem, which was to perform a maxillary nerve block in a patient with difficult anatomy. The approach and technique were clearly thought out with an excellent result. The axial cuts demonstrate needle position under CT scan and the appropriate spread of contrast material through the pterygopalatine fossa.
Anesthesia (16)
Authors: Calvillo Octavio , Skaribas Ioannis M. , Rockett Carl
Published: September 2010

Computed tomography—guided pudendal nerve block. A new diagnostic approach to long‐term anoperineal pain: a report of two cases. (Baylor College of Medicine, Houston, TX) Reg Anesth Pain Med 2000;25:420–423.

This report showed the value of computed tomography (CT) in selectively blocking the pudendal nerve in patients with long‐term anogenital pain of uncertain etiology. In 1 patient, a competitive cyclist, blocking the nerve under CT substantiated the diagnosis of pudendal neuralgia. The procedure relieved the pain for approximately 24 h. In the other patient, pudendal nerve block produced perineal analgesia, but no pain relief. Superior hypogastric plexus block relieved the pain significantly for about 4 weeks on 2 separate occasions, suggesting sympathetically maintained pain. Conclude that the use of CT to guide the procedure allowed precision in performing the procedure and in making a differential diagnosis.
Anesthesia (18)
Authors: Casati Andrea , Magistris Luca , Fanelli Guido
Published: September 2010

Small‐dose clonidine prolongs postoperative analgesia after sciatic‐femoral nerve block with 0.75% ropivacaine for foot surgery. (University of Milan, Milan, Italy) Anesth Analg 2000;91:388–392.

This study evaluated the effects of adding small‐dose clonidine to 0.75% ropivacaine during peripheral nerve blocks, 30 ASA physical status I and II patients undergoing hallux valgus repair under combined sciatic‐femoral nerve block were randomly allocated in a double‐blinded fashion to receive block placement with 30 mL of either 0.75% ropivacaine alone (Group Ropivacaine, n = 15) or 0.75% ropivacaine plus μg/kg clonidine (Group Ropivacaine‐Clonidine, n = 15). Hemodynamic variables, oxygen saturation, and levels of sedation, as well as the time required to achieve surgical block and time to first analgesic request, were recorded by a blinded observer. Time to surgical blockade required 10 min in both groups. Patients in the Ropivacaine‐Clonidine Group were more sedated than patients in the Ropivacaine Group only 10 min after block placement. No differences in oxygen saturation and hemodynamic variables, degree of pain measurement at first analgesic request, and consumption of postoperative analgesics were observed between the two groups. The mean time from block placement to first request for pain medication was shorter in Group Ropivacaine (13.7 h; 25th–75th percentiles: 11.8–14.5 h) than in Group Ropivacaine‐Clonidine (16.8; 25th–75th percentiles: 13.5–17.8 h) (P = 0.038). Conclude that adding 1 μg/kg clonidine to 0.75% ropivacaine provided a 3‐h delay in first request for pain medication after hallus valgus repair, with no clinically relevant side effects.
Anesthesia (19)
Authors: Steinbrook Richard A. , Concepcion Mercedes A.
Published: September 2010

Respiratory gas exchange and hemodynamics during lumbar epidural anesthesia: effects of lidocaine with and without epinephrine. (New England Medical Center, Tufts University School of Medicine, Boston, MA) Reg Anesth Pain Med 2000;25:380–384.

In this study, 12 healthy patients (age, 22 to 46 years) undergoing surgery on the knee were randomly assigned to receive either 2% lidocaine (Group L) or 2% lidocaine with epinephrine 5 μg · mL−1 (Group E), approximately 20 mL, over 10 min via lumbar epidural catheter. Total‐body oxygen consumption (VO2) and carbon dioxide production (VCO2) were determined by indirect calorimetry; hemodynamic measurements were obtained by noninvasive thoracic electrical bioimpedance. Values of VO2, VCO2, heart rate (HR), cardiac index (CI), and mean arterial blood pressure (MAP) were determined every minute and averaged every 5 min for 30 min. Comparisons were made with analysis of variance (ANOVA) (within groups) and t‐tests (between groups). Differences were considered significantly different if P < 0.05. VO2 did not change in either group, while VCO2 increased significantly by 22% at 20 min in Group E. Increases in HR were apparent in both groups, with significantly greater increases in Group E. CI did not change in Group L, but increased by 41% in Group E. MAP decreased significantly by 11% in Group E, but did not change in Group L. Conclude that the addition of epinephrine, 5 μg · mL−1, to the epidural injection of 2% lidocaine is associated with changes not only in hemodynamics, but also in respiratory gas exchange.
Anesthesia (2)
Authors: Buchheit Thomas , Crews James C.
Published: September 2010

Lateral cervical epidural catheter placement for continuous unilateral upper extremity analgesia and sympathetic block. (Wake Forest University School of Medicine, Winston‐Salem, NC) Reg Anesth Pain Med 2000;25:313–317.

This article discussed the use of a laterally directed cervical epidural catheter for the treatment of acute and chronic pain. The technique was used in a series of 30 patients to produce unilateral upper extremity analgesia and sympathetic block. A case report of a patient treated with this technique and a description of the technique as well as the results from the series are presented. The method included placement of an epidural catheter at the C6‐7 vertebral interspace; the needle bevel and catheter were directed to the affected side in a woman with a history of complex regional pain syndrome of the right upper extremity. A unilateral block was shown with the technique by anatomic parameters (unilateral contrast dye spread), physiologic parameters (unilateral Horner's syndrome), and symptomatic parameters (unilateral, subjective neural block). One patient treated with the technique had bilateral effects; however, no patient had a predominant block on the contralateral side and no complications developed. The case report showed results that were typical of the series of 30 patients. Conclude that the laterally directed cervical epidural catheter was an effective technique to produce continuous unilateral analgesia and sympathetic block.
Anesthesia (20)
Authors: Schuepfer Guido , Konrad Christoph , Schmeck Joachim , Poortmans Gert , Staffelbach Bruno , Jöhr Martin
Published: September 2010

Generating a learning curve for pediatric caudal epidural blocks: an empirical evaluation of technical skills in novice and experienced anesthetists. (Institute of Anesthesiology, Lucerne, Switzerland) Reg Anesth Pain Med 2000;25:385–388.

The aim of this study was to assess the number of caudal blocks needed to guarantee a high success rate in performing caudal epidural analgesia in children. The technical skills of 7 residents in anesthesiology who performed caudal blocks were evaluated during 4 months using a standardized self‐evaluation questionnaire. At the start of the study period, the residents had no prior experience in pediatric anesthesia or in performing caudal epidural blocks. All residents entered the pediatric rotation after a minimum of 1 year of training in adult general and regional anesthesia. The blocks were rated using a binary score. For comparison, the success rates of 8 experienced staff anesthesiologists were collected during the same period using the same self‐evaluation questionnaire. Statistical analyses were performed by generating individual and institutional learning curves using the pooled data. The learning curves were calculated with the aid of a least‐square fit model and 95% confidence intervals were estimated by a Monte‐Carlo procedure with a bootstrap technique. The success rate of residents was 80% after 32 procedures (95% confidence interval of 0.59 to 1.00). The pooled success rate of the staff anesthesiologists was 0.73 (mean) with a standard deviation of 0.45, which was not statistically different from the success rate of the residents. Conclude that high success rates in performing caudal anesthesia in pediatric patients can be acquired after a limited number of cases. Success rates of residents learning this procedure are comparable to the results of the staff anesthesiologists.
Basic Science (23)
Authors: Kissin Igor , Bright Cheryl A. , Bradley Edwin L.
Published: September 2010

Acute tolerance to continuously infused alfentanil: the role of cholecystokinin and N‐methyl‐D‐aspartate‐nitric oxide systems. (Brigham and Women's Hospital, Boston, MA) Anesth Analg 2000;91:110–119.

To test the role of cholecystokinin (CCK) and N‐methyl‐D‐aspartate‐nitric oxide (NMDA‐NO) systems in the development of acute tolerance to analgesia during alfentanil IV infusion, experiments were conducted in rats with the use of an infusion algorithm designed to maintain a constant plasma level of the opioid for 4 h. The degree of acute tolerance was determined on the basis of decline in the level of analgesia measured with a tail compression test. CCKB receptor antagonists (proglumide, CI‐988, and L‐365,260) and NMDA‐NO cascade inhibitors (dizocilpine and NO synthase inhibitor) were administered before the start of alfentanil infusion. Use of 30 mg/kg proglumide, 10 mg/kg CI‐988, and 1 mg/kg L‐365,260 attenuated acute tolerance at 1 h of alfentanil infusion by approximately 60%, 55%, and 70%, respectively, and by the end of the 4‐h infusion by 50%, 50%, and 25%, respectively. Use of 0.1 mg/kg dizocilpine and 10 mg/kg NG‐nitro‐L‐arginine methyl ester attenuated acute tolerance at 1 h of alfentanil infusion by approximately 65% and 65% and by the end of the 4‐h infusion by 30% and 0%, respectively. Comparison of the results with CCKB receptor antagonists and inhibitors of NMDA‐NO cascade demonstrates that both groups provide more or less similar degrees of attenuation of acute tolerance to the antinociceptive effect of alfentanil, and none of these drugs completely prevents tolerance development.
Basic Science (24)
Authors: Li Xinhui , Zhao Zhihong , Pan Hui‐Lin , Eisenach James C. , Paqueron Xavier
Published: September 2010

Norepinephrine release from spinal synaptosomes. (Wake Forest University School of Medicine, Winston‐Salem, NC) Anesthesiology 2000;93:164–172.

The purpose of this study was to determine if clonidine could inhibit release of NE in a preparation of spinal cord tissue lacking synaptic circuits. Crude synaptosomes were prepared from male Sprague‐Dawley rat spinal cord, loaded with [3H]NE, and stimulated by potassium chloride to release [3H]NE. Samples were incubated with clonidine in the absence or presence of various inhibitors. To study the effect of α2A‐adrenergic receptor subtypes, some animals were pretreated with an oligodeoxynucleotide (ODN) composed of a sense or antisense sequence to a portion of this receptor. Potassium chloride produced a concentration‐dependent increase in [3H]NE release, and this release was inhibited by clonidine with a concentration producing 50% maximal inhibition (IC50) of 1.3 μm. The effect of clonidine was inhibited by the α2A‐adrenergic antagonists, yohimbine, and idazoxan, but not by α1A‐adrenergic, muscarinic, or opioid antagonists. Intrathecal pretreatment with antisense ODN to α2A‐adrenergic receptors reduced α2A‐adrenergic receptor protein expression compared with sense ODN control and also reduced clonidine‐induced inhibition of [3H]NE release. Conclude that these data demonstrate the existence of classic autoinhibitory α2A‐adrenergic receptors in the spinal cord, probably of the α2A subtype. They further suggest that clonidine‐induced stimulation of spinal NE release must occur from indirect actions, presumably due to activation of a spinal circuit.
Basic Science (26)
Authors: Khodorova Alla B. , Strichartz Gary R.
Published: September 2010

The addition of dilute epinephrine produces equieffectivenes of bupivacaine enantiomers for cutaneous analgesia in the rat. (Brigham and Women's Hospital, Boston, MA) Anesth Analg 2000;91:410–416.

This study investigated the effectiveness for cutaneous analgesia of bupivacaine (Bup) stereoisomers in male rats. As a model of infiltration anesthesia, inhibition of a nocifensive reflex by subcutaneous injection of 0.6mL of different concentrations of R‐, S‐, and racemic‐Bup was evaluated quantitatively by the fraction of times a pinprick failed to evoke a nocifensive motor response. R‐Bup was more potent in the extent of the block; however, S‐Bup had a longer‐lasting action at smaller doses. This significant difference was apparent when R‐Bup and S‐Bup were administered in equipotent doses of 0.06% and 0.075%, respectively. Co‐injection of epinephrine (Epi) with these equipotent doses enhanced and prolonged the blocking effects of both Bup stereoisomers, although the dilutions of 1:100,000 to 1:1,000,000 Epi itself induced partial, transient analgesia. At 1:2,000,000 dilution, Epi alone had no analgesic effect; however, when co‐injected with the shorter‐acting R‐Bup (0.06%), Epi prolonged its blocking effect to equal the duration of the block evoked by equipotent S‐Bup (0.075%). Conclude that R‐Bup is more potent for cutaneous analgesia and that the longer duration of the block by S‐Bup probably originates from vasoconstrictor activity.
Basic Science (28)
Authors: Kawamata Tomoyuki , Omote Keiichi , Sonoda Hajime , Kawamata Mikito , Namiki Akiyoshi
Published: September 2010

Analgesic mechanisms of ketamine in the presence and absence of peripheral. (Sapporo Medical University School of Medicine, Sapporo, Japan) Anesthesiology 2000;93:520–528.

In this study, the authors investigated the contribution of the supraspinal monoaminergic descending inhibitory system to ketamine analgesia for acute nociception and inflammation‐induced hyperalgesia. Male Sprague‐Dawley rats were used. The paw withdrawal latencies to radiant heat stimuli were measured to assess the thermal nociceptive threshold. The analgesic effects of intrathecal or intraperitoneal ketamine were examined in the rats that received unilateral intraplantar carrageenan and in those that were untreated. In addition, it was examined whether pretreatment with intrathecal yohimbine or methysergide inhibited the analgesic effects of ketamine. Using an intrathecal microdialysis method, noradrenaline and 5‐hydroxytryptamine concentrations in lumbar cerebrospinal fluid were measured after intraperitoneal ketamine in both saline‐ and carrageenan‐treated rats. In the untreated rats, intraperitoneal but not intrathecal ketamine produced antinociceptive effects in a dose‐dependent manner. Pretreatment with intrathecal yohimbine or methysergide inhibited these antinociceptive effects. Intraplantar carrageenan significantly reduced paw withdrawal latencies on the injected paw, but not on the contralateral paw. Both intraperitoneal and intrathecal ketamine reversed the shortened paw withdrawal latencies on the injected side in a dose‐dependent manner without any effects on the contralateral side. Neither yohimbine nor methysergide inhibited these antihyperalgesic effects. In analyses of monoamines, the magnitiute of increase in monoamines after intraperitoneal ketamine was significantly smaller in the carrageenan‐treated rats than in the saline‐treated rats. Conclude that these results demonstrated that ketamine produced antinociceptive effects through an activation of the monoaminergic descending inhibitory system, whereas, in a unilateral peripheral inflammation‐induced hyperalgesic state, the monoaminergic system did not contribute to the antihyperalgesic effects of ketamine. The mechanisms of the antinociceptive and antihyperalgesic properties of ketamine are different.
Basic Science (29)
Authors: Pogatzki Esther M. , Zahn Peter K. , Brennan Timothy J.
Published: September 2010

Effect of pretreatment with intrathecal excitatory amino acid receptor antagonists on the development of pain behavior caused by plantar incision. (University of Iowa, Iowa City, Iowa) Anesthesiology 2000;93:489–496.

This study examined the role of N‐methyl‐D‐aspartate (NMDA), non‐NMDA, and metabotropic glutamate receptors (MGluRs) on the development of pain behavior after plantar incision. Rats with lumbar intrathecal catheters were anesthetized with halothane. Fifteen minutes before an incision was made, drug [40 nmol MK‐801; 20 nmol NBQX; or 200 nmol [(+)‐MCPG] or vehicle was injected intrathecally followed by an infusion of the same drug for 75 min. Withdrawal thresholds to calibrated von Frey filaments applied adjacent to the wound and response frequencies to a blunt mechanical stimulus applied directly to the wound were measured before incision and 1, 2, 4, and 6 h after incision and then once daily for 6 days. Preincision treatments with antagonists against the NMDA (MK‐801) and Group I and II metabotropic receptors [(+)‐MCPG] did not inhibit the development of mechanical hyperalgesia caused by incision. Preincision treatment with the non‐NMDA receptor antagonist NBQX increased withdrawal thresholds at 1 and 2 h and on postoperative day 1 compared with the vehicle group; response frequencies were reduced 1 and 2 h after incision and on postoperative day 2 (P < 0.05). In an additional group, postincision treatment with NBQX was similar to preincision treatment. Conclude spinal NMDA and MGluR antagonists may not be useful for preventing postsurgical pain. Spinal non‐NMDA receptor antagonists reduced pain behaviors, but a preventive effect using preincision treatment was not apparent.

Comment by James E. Heavner, DVM, PhD.

The incisional model using rats was developed by Dr. Brennan and colleagues for the study of acute surgical pain. In a previous study, they showed that blockade of non‐NMDA excitatory amino acid receptors, but not blockade of NMDA receptors nor mGluR receptors reduces postincisional pain if administered after the incision is made. This study shows the same is true if the receptor antagonists are administered before the incision is made. However, the effect is not particularly marked and; therefore, pursuit of non‐MNDA excitatory amino transmitter receptor blockers for the prevention of postincisional pain would not likely be fruitful. The results of the study do require us to rethink how postincisional pain differs from other experimental pains and the phenomena of “wind‐up” attributed to activation of the NMDA receptor. Worth keeping in mind is that incisional pain does not equal surgical pain, which may involve traumatic injury to nerves and produce a neuropath pain, which strongly indicates involvement of NMDA receptors.
Anesthesia (3)
Authors: Burm Anton G.L. , Stienstra Rudolf , Brouwer Rolf P. , Emanuelsson Britt‐Marie , Van Kleef Jack W.
Published: September 2010

Epidural infusion of ropivacaine for postoperative analgesia after major orthopedic surgery. (Leiden University Medical Center, Leiden, The Netherlands) Anesthesiology 2000;93:395–403.

This study evaluated the pharmacokinetics of ropivacaine administered by 72‐h epidural infusion to provide postoperative analgesia. Twenty‐eight patients scheduled for major orthopedic surgery during combined epidural and general anesthesia received a bolus dose of ropivacaine (50 or 70 mg), followed by constant‐rate (10 mL/h) epidural infusion of ropivacaine 2 mg/mL (Group 1) or 3 mg/mL (Group 2). Total and unbound plasma concentrations of ropivacaine and pipecoloxylidide and plasma concentrations of α1‐acid glycoprotein were determined. The urinary excretion of ropivacaine and major metabolites was measured. Results showed that total plasma concentrations of ropivacaine increased steadily during infusion and unbound ropivacaine concentrations reached average steady levels of approximately 0.06 and 0.07 mg/l. Total and unbound concentrations of pipecoloxylidide increased to 1.0 ± 0.4 and 0.4 ± 0.2 mg/l (Group 1) and 1.2 ± 0.4 and 0.5 ± 0.1 mg/l (Group 2) after 72 h infusion. α1‐Acid glycoprotein concentrations initially decreased, but thereafter increased steadily to approximately twice the baseline values. Conclude postoperative increases in plasma α1‐acid glycoprotein concentrations enhance the protein binding of ropivacaine and pipecoloxylidide, which causes divergence of total and unbound plasma concentrations.