Administration Of Analgesic Drugs Research Articles

Pain management in horses and farm animals

AbstractObjective:This review discusses the different analgesic drugs and routes of administration used in large animals for acute pain management. General guidelines and doses are given to assist in choosing techniques that provide effective analgesia.Etiology:Noxious stimuli are perceived, recognized, and localized by specialized sensory systems located at spinal and supraspinal levels.Diagnosis:Localizing the source of the noxious stimulus as well as understanding the behavioral aspects and physiological changes that result from such insult is important to adequately diagnose and treat pain. Pain assessment is far from being definite and objective; not only are there species differences, but also individual variation. In addition, the behavioral and physiological manifestations vary with the acute or chronic nature of pain.Therapy:Pain management should include (1) selecting drugs that better control the type of pain elicited by the insult; (2) selecting techniques of analgesic drug administration that act on pathways or anatomical locations where the nociceptive information is being processed or originating from; (3) combining analgesic drugs that act on different pain pathways; and (4) provide the best possible comfort for the animal.Prognosis:Providing pain relief improves the animal's well being and outcome; however, interpreting and diagnosing pain remains difficult. Continuing research in pain management will contribute to the evaluation of the pathophysiology of pain, pain assessment, and newer analgesic drugs and techniques.

Characteristics of pain and response to analgesic treatment in dogs and cats examined at a veterinary teaching hospital emergency service

To estimate the prevalence and characteristics of pain in dogs and cats examined by an emergency service at a veterinary teaching hospital and evaluate the response of dogs and cats with signs of pain to analgesic treatment. Cross-sectional study. 317 dogs and 112 cats. A questionnaire was used to categorize the characteristics of pain. The location, cause, and signs of pain were determined by obtaining a thorough history and conducting a physical examination. Pain was categorized by type (superficial somatic, deep somatic, or visceral), mechanism (inflammatory, neuropathic, or both), severity (mild, moderate, or severe), and duration. Evidence for primary or secondary hypersensitivity and hyposensitivity to manipulation was determined. The response to single or multiple analgesic drug administration was assessed. 179 (56%) dogs and 60 (54%) cats had signs of pain. In most of these dogs and cats, pain was classified as acute (< 24 hours' duration) and of moderate severity and was associated with primary hypersensitivity. Most dogs had deep somatic pain; most cats had visceral pain. Inflammation was the most common mechanism. One hundred nineteen (66%) dogs and 41 (68%) cats were treated with analgesic drugs. Analgesic treatment was considered effective in 73 (61%) dogs and 31 (76%) cats. Results suggest that moderate to severe acute somatic pain caused by inflammation is common in dogs and cats examined by an emergency service and that a combination of multiple analgesic drugs is more effective than any single analgesic drug in the treatment of pain in these dogs and cats.

Treatment of Pain and Stress in the Neonate

After completing this article, readers should be able to: 1. Describe the pain assessment tools used for preterm and term neonates. 2. List painful procedures in the neonatal intensive care unit (NICU). 3. Describe nonpharmacologic interventions for alleviating neonatal pain. 4. Describe pharmacologic methods used for neonatal analgesia. 5. Delineate the adverse effects of the common forms of pain relief. Neonates are sensitive to pain and vulnerable to both its short- and long-term effects. However, there is a lack of consistency in both attitudes and practices among NICU staff with regard to pain assessment and management in neonates. Recognition of the clinical importance of neonatal pain and stress has been delayed and hampered by the lack of awareness that newborns are capable of experiencing pain, insufficient knowledge about the developing nervous system, difficulty in assessing neonatal pain, lack of evidence for the safety and efficacy of different modalities available for the treatment of pain, and fears about adverse effects associated with analgesic use. Neonatal pain has been of minimal concern until the last 25 years. For example, at one time, neonates were given paralytic drugs without anesthesia for major surgical procedures because physicians believed that neonates were incapable of interpreting or remembering pain. Further, there was no understanding of the consequences of untreated pain. Newer technologies to sustain life have exposed neonates to multiple invasive procedures and prolonged hospital stays that are associated with acute and chronic pain and stress. In 2001, an international evidence-based group for neonatal pain developed guidelines for the assessment, prevention, and treatment of neonatal pain in an effort to standardize practices for physicians and health care facilities. Within the consensus statement, the group defined general principles to prevent and treat pain and listed the most commonly performed diagnostic, therapeutic, and surgical procedures in the NICU. The guidelines also indicated the …

Subarachnoid Analgesia in Advanced Labor: A Comparison of Subarachnoid Analgesia and Pudendal Block in Advanced Labor: Analgesic Quality and Obstetric Outcome

Pain control during labor is a primary objective of antalgic therapy. The use of the peridural as an elective procedure for labor analgesia is now corroborated by the international scientific community. Sometimes a combined spinal-peridural procedure is used together with the intrathecal administration of opioids to also cover the first stage of labor. Unfortunately, patients and/or gynecologists often request analgesia in a late stage of labor. The aim of our study was to evaluate the possibility of using a subarachnoid block alone for labor analgesia when this is requested at a late stage, that is, in advanced labor with cervical dilation greater than 7 cm. After approval by our ethics committee and the written and informed consent of the patients, 111 women were enrolled in this study and randomly divided into two groups. The first group (Group S: 55 patients) received a subarachnoid block with 2.5 mg hyperbaric bupivacaine + 25 mug fentanyl + 1 mL 10% glucose. A pudendal nerve block with 7 mL 2% mepivacaine in each side was administered to the second group (Group P: 56 patients). In both groups, careful maternal-fetal monitoring was conducted, and pain was scored on a numerical scale from 0 to 4, 10 minutes after placement of the block (time [T] 0), at delivery (T1), and at episiorrhaphy (T2). In all patients, we recorded any side effects, the Apgar score at birth and after 5 minutes, the administration of other analgesic and/or sedative drugs, the degree of satisfaction, and the time of hospitalization after delivery. Evaluations were performed by anesthesiologists unaware of patients' treatment group. The duration of spinal analgesia was considered to be the time from injection of study drugs to the time of the patient's first request for additional analgesia. In no cases were there any side effects worthy of note, and hospitalization never exceeded 72 hours. The Apgar score was always between 7 and 10. All except one of the women in Group S were satisfied or more than satisfied with their pain management, whereas 50 women in Group P expressed only moderate satisfaction or dissatisfaction (P < 0.0001). In most patients in Group S, complete analgesia was obtained. In Group P, however, 10 minutes after placement of the pudendal nerve block, 40 patients reported no improvement in pain symptomatology during contractions and only 16 reported less painful contractions (P < 0.0001). The duration of spinal analgesia (128 +/- 38 minutes) was enough in most cases for delivery to be completed. These results suggest that low-dose bupivacaine-fentanyl spinal analgesia represents an important option for pain relief in late labor, not the least because the procedure does not upset the dynamics of delivery or alter vital parameters and is welcomed by women in labor who are still able to collaborate actively in the birth of their baby.

A computer screen-based simulator for hierarchical fuzzy logic monitoring and control of depth of anaesthesia

A computer screen-based simulator has been developed to simulate the administration of intravenous and analgesic drugs. It merges on-line measurements (such as systolic arterial pressure (SAP) and heart rate (HR)) and nonnumerical clinical signs (such as sweating, lacrimation and pupil response), using anaesthetists' experience or self-organizing fuzzy logic control (SOFLC) algorithms to administer drugs into a patient. The hierarchical control architecture includes five parts, which are: monitoring depth of anaesthesia (DOA), drug controller, deciding the sensitivity of the patient, narcotic supplementation and recovery time. It has been developed to predict drug profiles, control the drug levels and assess recovery time during anaesthesia. Meanwhile, linguistic rules and fuzzy set theory have been used to model a patient's SAP and HR during induction and maintenance stages. Successful simulation results have given confidence to perform on-line clinical trials in operating theatre.

Emerging techniques in the treatment of postoperative pain.

Causes of inadequate postoperative pain control, challenges with currently available analgesic therapies, characteristics of optimal postoperative analgesic therapy, a liposome-encapsulated, sustained-release dosage form of morphine, and other investigational analgesic therapies are described. Technical difficulties in analgesic drug administration, inappropriate prescribing, unfounded patient fears or expectations, and the lack of availability of parenteral dosage forms of certain analgesic agents can potentially contribute to inadequate postoperative pain control. The use of epidural catheters for analgesic therapy is limited by the use of prophylactic anticoagulation, the tendency for catheters to migrate and fail, and the need for nursing staff time to monitor the catheter site and infusion pump. Continuous peripheral blocks are not always effective, the devices used are bulky, and the technology is prone to failure. Multimodal therapies are labor-intensive, and some components must be given orally because they are not available in parenteral dosage forms. Optimal postoperative analgesic drug therapy would therefore be noninvasive, easy to administer, require no cumbersome equipment, cause no or minimal adverse effects, and be safe to use in patients receiving prophylactic anticoagulation. A new morphine sulfate sustained-release liposome injection has several of these characteristics, including ease of administration and compatibility with anticoagulation. Single-dose epidural administration of morphine sulfate sustained-release liposome injection in patients undergoing hip arthroplasty provided better pain control than i.v. opioid analgesics given by PCA, with similar adverse effects. Opioid analgesics remain the mainstay of postoperative analgesic therapy, but the development of infusion pumps with improved reliability; needle-free technologies, parenteral dosage forms of acetaminophen, selective cyclooxygenase-2 inhibitors, and other non-opioid therapies; and new opioid analgesic agents that provide analgesia without the adverse effects of currently available opioid analgesics may substantially improve postoperative analgesia and health-related quality of life in the postoperative pain patient in the future.

Pain management in cats—past, present and future. Part 2. Treatment of pain—clinical pharmacology

Opioids have an unjustified reputation for causing mania in cats, but with refinements in dosing they are now used successfully in this species. The mu-opioid agonists are generally considered the best analgesics. Morphine (0.1–0.3 mg/kg) is effective in a clinical setting. Methadone (up to 0.5 mg/kg) has a similar profile to morphine. Pethidine (Demerol, meperidine; 2–5 mg/kg) is a useful analgesic with a faster onset but shorter duration of action than morphine. Oxymorphone and hydromorphone (0.05–0.1 mg/kg) are widely used in the USA. These opioids are more potent (up to 10 times), and longer acting than morphine in cats. Butorphanol (0.1–0.4 mg/kg) is a mu-opioid antagonist that produces its analgesic actions through kappa agonist activity. It rapidly reaches a ceiling effect, is short acting and is a weaker analgesic than pure mu opioids. Buprenorphine (0.01–0.02 mg/kg), a partial mu-agonist, is the most popular opioid used in small animal practice in the UK, other parts of Europe, Australia and South Africa. In clinical studies it has produced better analgesia than several other opioids and appears to be highly suitable for perioperative pain management in cats. NSAIDs are also used in cats for pain management, although cats metabolise these differently from other species. With appropriate dosing, carprofen (1–4 mg/kg) and meloxicam (0.3 mg/kg) have proved highly effective with few side effects. The use of ketoprofen (2 mg/kg), tolfenamic acid (4 mg/kg) and vedaprofen (0.5 mg/kg) has been reported in cats. Other less traditional analgesics such as ketamine, medetomidine and local anaesthetics are also used for clinical pain management. The transmucosal, transdermal and epidural routes offer novel methods for administration of analgesic drugs and have considerable potential for improving techniques in feline pain management.

Pharmacology of systemic analgesics

Systemic administration of analgesic drugs is still the most widely used method for providing pain relief in acute painful situations. Opioids may be selected on the basis of their physicochemical characteristics and their diffusion index to the brain. But in clinical practice, their very steep concentration–analgesic effect relationship remains a critical aspect of opioid therapy. Thus, small fluctuations in plasma concentrations of opioids may lead to profound fluctuations in analgesic effect when their plasma and effect-site concentrations are near the minimum effective analgesic concentration (MEAC). Combining drugs acting on different mechanisms of nociceptive modulation offers benefits from additive/synergistic effects and will decrease the incidence of their adverse effects. Evidence-based reviews showed that effective pain relief using non-opioid analgesics relied on paracetamol supplemented with non-steroidal anti-inflammatory drugs (NSAIDs). The role of COX-2 selective inhibitors (CSIs) in acute pain relief still requires further evaluation. NSAIDs, CSIs and paracetamol share the property of morphine sparing in situations of severe (post-operative) pain. CSIs may be beneficial in patients in whom post-operative bleeding is a major surgical risk as the effects of NSAIDs on coagulation may last for days. Finally, low-dose ketamine infusions remain a worthwhile addition to opioid therapy. Analgesic concentrations of ketamine are 1/5th to 1/10th the anaesthetic concentration and exert significant inhibition on N–methyl–d-aspartate (NMDA) receptor activation.

Postoperative nausea and vomiting after craniotomy for tumor surgery: a comparison between awake craniotomy and general anesthesia

Study Objective: To assess the frequency of postoperative nausea and vomiting (PONV) in patients following an awake craniotomy compared to general anesthesia for tumor surgery. Design: Prospective observational and chart review of all patients having a craniotomy for tumor during one year. Setting: Postanesthesia care unit (PACU) and intensive care unit (ICU) of a university hospital. Patients: 187 patients were reviewed. 107 patients who had a craniotomy for supratentorial tumor that was less than six hours in duration were analyzed and compared (50 awake craniotomy vs . 57 general anesthesia). Interventions: Medical records were reviewed for events after the first four hours until discharge. The occurrence and the time of any nausea, vomiting; the administration of antiemetics and analgesic drugs; and complications were documented. Measurements: Frequency of nausea, vomiting, administration of antiemetics and analgesia, and outcome between the two groups were compared using Chi-square and Student’s t -test. Main Results : The frequency of nausea (4% vs. 23%; p = 0.012) and vomiting (0% vs. 11%; p = 0.052) were less in patients having an awake craniotomy compared to general anesthesia, but only during the first four hours. The administration of postoperative analgesia was not different between the two groups and did not influence the frequency of PONV. Conclusion: The frequency of PONV during the initial recovery phase was less in patients having an awake craniotomy for tumor surgery than in patients having a similar procedure with general anesthesia.

Managing pain in children: An observational study

This paper describes an observational study which examined how nurses (n=13) managed pain in one surgical ward in the Midlands. The results indicate that, while the nurses were good at giving analgesic drugs, general nursing care related to pain management was poor; for example, pain assessment was not undertaken systematically and non-drug methods of pain relief were rarely used. This was despite the ward being particularly quiet during the period of observation. The majority of prescribed doses of analgesia were within therapeutic levels. The results of the study add weight to the supposition put forward by Francke et al. (1997) that many nurses hold a one-sided view of pain management and believe that the nurse's role in pain management is synonymous with the administration of analgesic drugs. Other nurses hold an integrated view and believe that, in addition to pharmacological interventions, psychosocial and other non-drug interventions may be valuable in pain management. It is also postulated that poor pain management may be due to the stress inherent within nurses' role and associated with caring for children in pain.

Routine versus “on demand” sedation and analgesia for colonoscopy: a prospective randomized controlled trial

Background: The safety and tolerance of routine sedation and analgesia versus “on demand” sedation were compared in patients undergoing colonoscopy. Methods: Two hundred forty-nine outpatients were randomly assigned to one of two groups. Group A (n = 125) received midazolam, 0.07 mg/kg intravenously plus meperidine, 0.77 mg/kg intravenously immediately preceding the colonoscope insertion. Group B (n = 124) received the same medication upon request during the procedure. Tolerance was assessed 24 hours later by phone interview performed by a nurse blinded to the medication regimen administered. Results: Eighty-three patients (66%) in Group B required sedation during colonoscopy. Among men in Group B more than 60 years of age, only 23% required sedation. The proportion of patients reporting moderate or severe pain (34% vs. 12.1%, p < 0.001) and of those stating they would not be willing to undergo colonoscopy again in the future (22% vs. 9.7%, p < 0.005) was significantly higher in the “on demand” sedation group. By multivariate analysis the randomization group was the single variable independently associated with both such outcomes. The frequency of side effects was similar in the two groups. Conclusions: Administration of sedative and analgesic drugs routinely before colonoscopy is superior to “on demand” sedation in terms of tolerance and is not associated with an increase in side effects. (Gastrointest Endosc 2001;54:169-74.)

Theoretical basis of target controlled anaesthesia: history, concept and clinical perspectives

The technique of target controlled infusion (TCI) has influenced the development of intravenous anaesthesia substantially and opened the possibility of many new and exciting applications in peri-operative anaesthetic care. The launch of ‘Diprifusor™’ as the first commercially available TCI system for propofol in 1996 was the cornerstone of a successful research period within the last decade, which evaluated the pharmacokinetic foundations of computer assisted intravenous drug delivery. We are now in a period where TCI technology is becoming a part of the routine anaesthetic techniques for the practitioner rather than a research tool for specialists and enthusiasts. This review gives an overview of the history of target controlled anaesthesia, the rational pharmacokinetic basis of TCI development, the preliminary clinical experience with the new technique, the performance and accuracy of available TCI devices and the potential technical pitfalls in clinical routine. Although these developments were predominantly made with intravenous anaesthetic drugs, the knowledge of target controlled anaesthesia can principally be transferred to the administration of inhalational drugs, especially in the advent of new quantitative anaesthesia machines. As well as the clinical application of TCI with propofol and, in the near future, with remifentanil, target controlled systems are expected to play a significant role as research tools in the evaluation of drug interactions in anaesthesia, in the development of novel control techniques for the administration of sedative and analgesic drugs in the peri-operative period, and in optimizing the accuracy of feedback control systems.

Thoracoscopy as a Nonpharmacotherapeutic Research Modification for Limiting Postoperative Chest Pain

Diminished tissue injury and shortened clinical recovery are benefits of using an endoscopic approach for patients needing operative procedure. In the course of developing an experimental model requiring procurement of topographically precise lung biopsy specimens, we sought to apply thoracoscopy as a research alternative to thoracotomy. In addition, we investigated the influence of thoracoscopy on postprocedure recovery practices using rabbits divided into four treatment groups. Rabbit groups 1 and 2 underwent thoracoscopy and lung biopsy while maintained by one-lung anesthesia. Additionally, group 2 had ketoprofen and bupivacaine HCl analgesics injected for treatment during postprocedure recovery. These two groups were compared to control rabbits in groups 3 and 4, which underwent inhalant anesthesia without thoracoscopy. Control group 3 also received the injection analgesic combination. During recovery, rabbit behavior was systematically assessed for evidence of pain. No behavior considered indicative of pain needing intervention was observed regardless of treatment group. Limited changes in plasma corticosterone, catecholamines, and prostaglandin E2 levels measured during recovery were difficult to associate with any treatment. Unexpectedly, significantly different mean corticosterone and catecholamines levels were detected in rabbits given the injection analgesic combination in the absence of thoracoscopic procedure, as compared to other treatment groups. The results highlight the importance of awareness that analgesic drug administration has the potential to alter homeostasis and affect interpretation of some study findings by its own guise. Correlation of the mean pain study results with plasma biochemical data supports preferential use of thoracoscopy as a refinement for limiting postprocedural pain in research models.

Target controlled infusion (TCI)--status and clinical perspectives

The technique of target controlled infusion (TCI) has influenced the development of intravenous anaesthesia substantially and opens the possibility of many new and exciting applications in peri-operative anaesthetic care. The launch of "Diprifusor" as the first commercially available TCI system for propofol was the cornerstone of a successful research period within the last decade, which evaluated the pharmacokinetic foundations of computer assisted intravenous drug delivery. We are now in a period where TCI technology is becoming a part of routine anaesthesia technique for the practitioner rather than a research tool for specialists and enthusiasts. This review gives an update on the rational pharmacokinetic basis of TCI development, the preliminary clinical experience with the new technique, the performance and accuracy of TCI devices and potential technical pitfalls in clinical routine. Besides clinical application in anaesthesia with "Diprifusor" TCI, target controlled systems are expected to play a significant role as research tools in the evaluation of drug interactions in anaesthesia and in the development of novel control techniques for the administration of sedative and analgesic drugs in the peri-operative period.

Management of postoperative pain in abdominal surgery in Spain. A multicentre drug utilization study.

Postoperative pain is common in hospital-admitted patients. Its management is determined by different therapeutic traditions and by the attitudes of health professionals in each hospital. The aim of this study was to describe the patterns of prescription and administration of analgesic drugs used for postoperative pain after abdominal surgery in Spanish hospitals, to know the prevalence and the severity of postoperative pain, and to determine the extent of variability in the management of postoperative pain among the participating centres. The study was a multicentre descriptive cross-sectional drug utilization study in 12 Spanish hospitals. The subjects were an unselected sample of consecutive patients undergoing abdominal surgery, admitted between October 1994 and January 1995. For each patient, information about the surgical procedure and the use of analgesics was prospectively collected. The severity of postoperative pain was assessed during the first day after surgery by means of a six-category (none, mild, moderate, severe, very severe, and unbearable) rating scale and a visual analogue scale (VAS). Nine hundred and ninety-three patients (547 men) were included. The most common surgical procedures were inguinal hernia repair (315, 32%), cholecystectomy (268, 27%), appendectomy (140, 14%), bowel resection (137, 14%), and gastric surgery (58, 6%). Fifty-nine percent of patients (587) received nonopioid analgesics only, 9% (89) received opioid analgesics only, and 27% (263) received both opioid and nonopioid analgesics. The most frequently administered drugs were metamizole (667 patients) and pethidine (213 patients). Although in the majority of medical orders the administration of analgesics was scheduled at regular time intervals, the majority of actual doses were given 'as-needed'. The average administered daily doses of all analgesics were lower than those prescribed. Thirty-eight percent (371/967) of patients rated their maximum pain on the first day as severe to unbearable. Wide interhospital variability was recorded in the surgical procedures which had been performed, in the analgesics used, and also in the pain scores referred by patients. The percentage of patients in each centre who suffered severe to unbearable pain varied from 22 to 67%. In Spain many patients still suffer severe pain after abdominal surgery, and this seems to be due to an inadequate use of analgesics. Wide interhospital variability in the management of postoperative pain and in its prevalence was also recorded.

Pain control in small-animal patients

An understanding of receptors and mechanisms involved in pain and suffering is essential in selecting proper methods of treatment. Detection of pain, knowing types of pain, and understanding reasons why presurgical administration of analgesic drugs (pre-emptive analgesia) is essential to relief of pain and distress. Animals feel pain to the same extent as humans and they have a wide variation in tolerance to pain stimuli as well. Animals may express pain or discomfort in two ways. Excessive activity or relative lethargy are both overt reflections of a painful state. Expressions of pain may be exhibited by moaning, groaning, crying, whimpering, looking at the painful area, licking or biting or simply a decrease in activity. Pain may be categorized as minor, moderate, or severe. Pain may be superficial, somatic (muscle and skin), or visceral or combinations. Moderate and severe pain always require treatment and visceral pain is usually more intense than somatic pain. Opiate receptors are the normal sites of action of several endogenous substances. There are three major types of opioid receptors designated as mu, kappa and sigma. Opioids and opioid antagonists have different affinities for different receptors. Agonist analgesics such as morphine, meperidine, fentanyl, and oxymorphone exert their effects by attaching to the mu receptors. A relatively pure antagonist, naloxone, will displace another compound on these receptors but exert little or no effect. The mixed drugs, agonist–antagonists or partial agonists, may be used as analgesics if no opioid compound has been used, or as antagonists to reverse the effects of an opioid on the mu receptor while at the same time not competing with the effects on the k receptor that is, preserving the analgesia provided by that receptor. Some of the mixed drugs are better agonists wile others are better antagonists. Animals recovering from surgery are often surprised and confused because they hurt and therefore sedation along with analgesia preanesthesia is often desirable and necessary for proper treatment of postsurgical pain. Therefore, giving an analgesic before surgery will be advantageous. The second choice is to give analgesics after surgery, but before recovery from anesthesia.

COMPARISON OF ANALGESIC RESPONSES TO INTRATHECAL ANALGESICS ADMINISTERED VIA PE-10 AND 32-GAUGE POLYURETHANE INTRATHECAL CATHETERS IN THE RAT

S288 Introduction: Intrathecal catheter implantation is routinely performed for the evaluation of both morphologic as well as pharmacologic effects of drugs. A recent study of the morphologic changes following intrathecal catheter implantation found that a 32 gauge polyurethane catheters (PU-32) produced less inflammatory reaction and reduced encapsulation compared to polyethylene (PE-10) tubing, while latencies to thermal challenges before and after normal saline injections did not differ at 7 days following implantation. [1] This reduction in the inflammatory response to the intrathecal catheter material might allow for a greater period for pharmacologic evaluation of intrathecally administered drugs.. However, no comparison of functional tests to analgesic drug administration via these different catheter systems has been reported. The purpose of this study was to compare analgesic testing following bolus drug analgesic administration via these two catheters over a period of 15 days in rats. Methods: Following IRB approval, 18 male Sprague-Dawley rats (260 +/- 43g) were studied. Catheters were cut from bulk PE-10 (Benton Dickinson, Sparks, MD) or PU-32 (Micor, Allison Park, PA) using a scalpel. To facilitate the bolus intrathecal injections, a 1-cm silastic extension catheter was attached to the proximal end of the PU-32 tubing using silicone adhesive. The coupling between these catheters was tested for leaks prior to insertion. Under pentobarbital anesthesia, the animals had catheters inserted via the cisterna magna and threaded 8.5 cm caudally so that the tip resided at the rostral portion of the lumbar enlargement. The catheters were flushed with saline and sealed with a stainless steel stylet. On the 5th and 15th day after implantation a 3 nmol bolus dose (8[micro sign]L) of morphine was administered followed by an 8[micro sign]L saline flush. Tail flick responses were evaluated at 30 minutes. At the end of the study the animals were perfused with a 10% formalin solution and position and integrity of the catheter examined. Tail flick responses (%MPE) were compared using repeated measures ANOVA. Post hoc testing was done using Bonferroni corrected t-tests. Data are presented as mean +/- SE. Results: Of the 11 PU-32 animals, 6 animals had significant resistance to injection by day 5. Tail flick responses in this group were 16.2 +/- 4.1. The analgesic responses (%MPE) on day 5 in the remaining 5 PU-32 animals was not different from the PE-10 group (Figure 1), but was significantly reduced compared to the PE-10 group on day 15. Examination of the catheter systems revealed material clogging in 60% of the PU-32 catheters.Figure 1Discussion: The findings of this study are somewhat surprising since the reduced inflammation and encapsulation previously reported with the PU-32 did not result in a prolonged period of utility compared to PE-10. The increased resistance to injection was likely a result of clogging of the catheters. These findings suggest that intrathecal PU-32 catheters may not be preferable to PE-10 when intermittent bolus administration is desired over many days.

Ocular Transmucosal Absorption and Toxicity of Sufentanil in Dogs

Ocular Transmucosal Absorption and Toxicity of Sufentanil in Dogs

Compliance in administration of prescribed analgesics.

In this noninterventional study, the implementation of 'modern' pain management in clinical practice was investigated by recording the regular prescription, administration and efficacy of analgesic drugs. This resulted in a reproducible and superficial quality control design for hospitals. One hundred and fifty surgical patients were followed during 5 days postoperatively. For every patient, pain, mood and sedation were measured using visual analogue and verbal descriptive scores; the prescription of analgesics at set times and administered doses of analgesics were also recorded. Only paracodeine and naproxen were administered regularly as prescribed, unlike paracetamol and morphine. The prescribed daily dose of morphine was only received by 4.2% of all patients. Although the postoperative pain treatment pathway was considered to be improved after better education and communication, in fact the opposite was found. This is probably caused by traditional thinking, lack of control and time pressure on the hospital staff and the subservient attitude of the patient.

Post-operative central hypersensitivity and pain: the pre-emptive value of pethidine for ovariohysterectomy

The effect of timing of analgesic drug administration on the severity of post-operative pain was investigated in dogs undergoing ovariohysterectomy using both subjective visual assessment scoring systems (VAS) and objective mechanical nociceptive threshold measurements using a novel handheld anti-nociceptiometric device. Forty dogs undergoing routine elective ovariohysterectomy were included in a randomised and double-blind study and assigned to one of three groups: (i) pre-operative analgesics; (ii) post-operative analgesics; (iii) no analgesics (saline injections). The analgesic used was pethidine (a short acting predominantly μ-opioid agonist), at a dose of 5.0 mg/kg (intramuscular). The post-operative administration of pethidine resulted in significantly higher sedation scores and significantly lower pain scores in the early post-operative period, but the dogs given pethidine pre-operatively had significantly lower pain scores than both the other groups at 8, 12 and 20 h post-extubation ( P<0.01, ANOVA). Mechanical thresholds measured at the distal tibia demonstrated the development of allodynia at 12 and 20 h post-extubation, and this was significantly prevented by the pre- ( P<0.01 at 12 h, P<0.05 at 20 h, Kruskal-Wallis and post hoc Dunn's), but not by the post-operative administration of pethidine. Mechanical nociceptive thresholds measured at the ventral midline (site of surgery) demonstrated post-operative hyperalgesia in all groups; this hyperalgesia was least in the pre-operative pethidine group. In summary, this study clearly shows pethidine to be an effective analgesic in dogs, albeit of short duration of action, when administered post-operatively, and, importantly, that it has a positive benefit in terms of post-operative outcome measures, when administered pre-operatively, possibly as a result of blocking or preventing the development of central sensitisation following surgical stimulation.