[Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy for Surgical Patients (revised version 2019)]

The treatment of any causal, procedure-specific and/or concomitant acute pain is an essential quality feature in any surgical subspecialty. An interdisciplinary and interprofessional pain therapy aims for an immediate improvement of the patients' quality of life, a reduction of the risk of postoperative morbidity and mortality in the medium term, prevention of any pain chronification in the long run as well as a reduction of hospitalization and sick leave. The "Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy" exists since 1992. In view of the continuously developing scientific evidence, updated guideline recommendations and interprofessionally designed treatment pathways, these agreements have been adapted to the current requirements and structural conditions of the German healthcare system. Thus, both aforementioned professional associations promote an up to date version of an "Agreement for the Organization of Pain Therapy for Surgical Patients", a precise recommendation and a manual for the acting partners in order to realize the abovementioned goals.

[Recommendations for the perioperative use of dipyrone : Expert recommendation of the working group on acute pain of the German Pain Society, the scientific working group on pain medicine of the German Society for Anesthesiology and Intensive Care Medicine and the surgical working group on acute pain of the German Society for Surgery with participation of representatives of the Drug Commission of the German Medical Association]

BACKGROUND

Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed; however, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis.

METHODS

As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies.

RESULTS

The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other nonopioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis.

CONCLUSION

The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

[Staff and organizational requirements for pain services in hospitals : A recommendation from the German Society for Anaesthesiology and Intensive Care Medicine]

Although pain services have been established in many hospitals, there is considerable heterogeneity among them with respect to organization of service, staff and qualifications of staff, and treatment approaches.With this recommendation, the German Society for Anesthesiology and Intensive Care Medicine defines requirements for pain services in hospitals with respect to organizational standards and staff qualifications. The therapy offered by pain services supplements the treatment provided by the other departments involved, ensuring the high quality of specialized pain management in all areas of the hospital. Pain services shall oversee treatment with specialized analgesia techniques as well as the involvement of consultants, bringing together in-hospital pain medicine expertise in one service with availability 24 h and 7 days per week via a single contact. The medical head of the pain service shall be a qualified provider of pain medicine as defined by the German Medical Association and as a minimum should also have undergone additional training in basic psychosomatic medicine. Further members of the medical staff should possess the credentials of a medical specialist: non-medical staff should have completed continuing education in the treatment of pain. Minimal guidelines for personnel resources were defined: these included a specific time frame for first contacts (20 min) and follow-up (10 min) for specific analgesic techniques and for the involvement of consultants (first contact 45 min, follow-up 20 min), with additional time for travel, set-up, training and quality management. In addition to definition of the space and equipment needed, each service should draft its own budget, and this should be adequate and plannable. Written agreements between the disciplines and transparent documentation, including patient-reported outcomes, are recommended to ensure quality. The provision of specialized pain therapy should have high priority over all disciplines or departments.

[Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy for Surgical Patients (revised version 2019)]

The treatment of any causal, procedure-specific and/or concomitant acute pain is an essential quality feature in any surgical subspecialty. An interdisciplinary and interprofessional pain therapy aims for an immediate improvement of the patients' quality of life, a reduction of the risk of postoperative morbidity and mortality in the medium term, prevention of any pain chronification in the long run as well as a reduction of hospitalization and sick leave. The "Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy" exists since 1992. In view of the continuously developing scientific evidence, updated guideline recommendations and interprofessionally designed treatment pathways, these agreements have been adapted to the current requirements and structural conditions of the German healthcare system. Thus, both aforementioned professional associations promote an up to date version of an "Agreement for the Organization of Pain Therapy for Surgical Patients", a precise recommendation and a manual for the acting partners in order to realize the abovementioned goals.

[Recommendations for the perioperative use of dipyrone : Expert recommendation of the working group on acute pain of the German Pain Society, the scientific working group on pain medicine of the German Society for Anesthesiology and Intensive Care Medicine and the surgical working group on acute pain of the German Society for Surgery with participation of representatives of the Drug Commission of the German Medical Association]

BACKGROUND

Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed; however, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis.

METHODS

As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies.

RESULTS

The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other nonopioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis.

CONCLUSION

The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

[Recommendations for the perioperative use of dipyrone : Expert recommendation of the working group on acute pain of the German Pain Society, the scientific working group on pain medicine of the German Society for Anesthesiology and Intensive Care Medicine and the surgical working group on acute pain of the German Society for Surgery with participation of representatives of the Drug Commission of the German Medical Association]

BACKGROUND

Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed; however, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis.

METHODS

As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies.

RESULTS

The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other nonopioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis.

CONCLUSION

The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

[Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy for Surgical Patients (revised version 2019)]

The treatment of any causal, procedure-specific and/or concomitant acute pain is an essential quality feature in any surgical subspecialty. An interdisciplinary and interprofessional pain therapy aims for an immediate improvement of the patients' quality of life, a reduction of the risk of postoperative morbidity and mortality in the medium term, prevention of any pain chronification in the long run as well as a reduction of hospitalization and sick leave. The "Agreement of the Professional Association of German Anesthesiologists and the Professional Association of German Surgeons for the Organization of Postoperative Pain Therapy" exists since 1992. In view of the continuously developing scientific evidence, updated guideline recommendations and interprofessionally designed treatment pathways, these agreements have been adapted to the current requirements and structural conditions of the German healthcare system. Thus, both aforementioned professional associations promote an up to date version of an "Agreement for the Organization of Pain Therapy for Surgical Patients", a precise recommendation and a manual for the acting partners in order to realize the abovementioned goals.

Staff and organizational requirements for pain services in hospitals : A recommendation from the German Society for Anaesthesiology and Intensive Care Medicine

Although pain services have been established in many hospitals, there is considerable heterogeneity among them with respect to organization of service, staff and qualifications of staff, and treatment approaches.With this recommendation, the German Society for Anesthesiology and Intensive Care Medicine defines requirements for pain services in hospitals with respect to organizational standards and staff qualifications. The therapy offered by pain services supplements the treatment provided by the other departments involved, ensuring the high quality of specialized pain management in all areas of the hospital. Pain services shall oversee treatment with specialized analgesia techniques as well as the involvement of consultants, bringing together in-hospital pain medicine expertise in one service with availability 24 h and 7 days per week via a single contact. The medical head of the pain service shall be a qualified provider of pain medicine as defined by the German Medical Association and as a minimum should also have undergone additional training in basic psychosomatic medicine. Further members of the medical staff should possess the credentials of a medical specialist: non-medical staff should have completed continuing education in the treatment of pain. Minimal guidelines for personnel resources were defined: these included a specific time frame for first contacts (20 min) and follow-up (10 min) for specific analgesic techniques and for the involvement of consultants (first contact 45 min, follow-up 20 min), with additional time for travel, set-up, training and quality management. In addition to definition of the space and equipment needed, each service should draft its own budget, and this should be adequate and plannable. Written agreements between the disciplines and transparent documentation, including patient-reported outcomes, are recommended to ensure quality. The provision of specialized pain therapy should have high priority over all disciplines or departments.

[Role of anesthesiology in pain medicine and palliative care treatment in German hospitals : Survey of department heads of anesthesiology on treatment structures]

BACKGROUND

The aim of this analysis was to describe the role of anesthesiology departments in pain medicine and palliative care services in German hospitals.

METHOD

In the year 2012, all heads of departments of anesthesiology registered with the German Society of Anesthesiology and Intensive Care Medicine were surveyed about structures of pain medicine and palliative care services in their hospitals using a standardized postal questionnaire.

RESULTS

Out of 408 returned questionnaires (response rate 47%) 403 could be evaluated. Of the hospitals 58% had a designated pain medicine service, in 36 (9%) of the hospitals this was organized as an independent department and in 195 (57%) as part of another department, mostly the department of anesthesiology. The "pain clinic" as an outpatient service was the most common form of structure for pain medicine services (41%). Inpatient pain medicine units were available in 77 (19%) of the hospitals and a partial inpatient unit in the form of a day hospital in 26 (7%) of the hospitals. For the care of inpatients from other departments, there was an intrahospital pain consultation service in 166 of the hospitals, which was the only structure for pain medicine in 32 of the 231 hospitals that reported having a designated pain medicine service. In 160 pain medicine services anesthesiologists were the only medical practitioners and in a further 18 both anesthesiologists and other specialists were available (orthopedist/orthopedic surgeons n = 6, internal medicine n = 4, psychiatrist n = 2, general practitioner = 1 and neurologist n = 1). Only two hospitals had no anesthesiologist in the pain medicine team and for the remaining 51 hospitals no information was provided. In 189 of the 231 hospitals with pain medicine services, there was at least 1 physician with special qualifications in pain management. In 97 (44%) of the hospitals psychologists were part of the team with 53 having at least 1 psychologist with a special qualification in chronic pain management. Of the hospitals, 16% had a specialized department for palliative care, in 32% a specialized palliative care service was part of another department, which was the department of anesthesiology in 30%. Of the hospitals 56% had a palliative care consultation service, 41% had a specialized inpatient palliative care unit, 6% an outpatient clinic, 4% a day hospital and in 16% a specialized outpatient palliative care (SOPC) serving the community was incorporated. Inpatient consultation services and the SOPC were more common when the department of anesthesiology was involved in the palliative care services.

CONCLUSION

In German hospitals, the departments of anesthesiology make a significant contribution to the provision of both pain medicine and palliative care services. Nevertheless, the respective structures of care are often incomplete or even lacking. There were shortcomings in terms of organization and qualification of the team in pain medicine services (e.g. no doctor with special qualifications in pain management or no psychologist). Palliative care services are more often organized as independent departments than as pain medicine services. Engagement of the anesthesiology department in palliative care is linked to a broader scope of the services provided, which might reflect the capacity of many anesthesiologists to work in an interdisciplinary manner and across interfaces.

[Inpatient acute pain management in German hospitals: results from the national survey "Akutschmerzzensus 2012"]

BACKGROUND

In 2007, the German national guidelines on "Treatment of acute perioperative and post-traumatic pain" were published. The aim of this study was to describe current structure and process data for acute pain management in German hospitals and to compare how the guidelines and other initiatives such as benchmarking or certification changed the healthcare landscape in the last decade.

METHODS

All directors of German departments of anesthesiology according to the DGAI ("Deutschen Gesellschaft für Anästhesiologie und Intensivmedizin", German Society for Anesthesiology and Intensive Care) were mailed a standardized questionnaire on structures and processes of acute pain management in their hospitals.

RESULTS

A total of 403 completed questionnaires (46 %) could be evaluated. Of hospitals, 81 % had an acute pain service (ASD), whereby only 45 % met defined quality criteria. Written standards for acute pain management were available in 97 % of the hospitals on surgical wards and 51 % on nonsurgical wards. In 96 %, perioperative pain was regularly recorded (generally pain at rest and/or movement, pain-related functional impairment in 16 % only). Beside these routine measurements, only 38 % of hospitals monitored pain for effectiveness after acute medications. Often interdisciplinary working groups and/or pain managers are established for hospital-wide control. As specific therapy, the patient-controlled analgesia and epidural analgesia are largely prevalent (> 90 % of all hospitals). In the last decade, intravenous and oral opioid administration of opioids (including slow release preparations) has become established in acute pain management.

CONCLUSION

The survey was representative by evaluating 20 % of all German hospitals. The organizational requirements for appropriate pain management recommended by the German guidelines for acute pain recommended have been established in the hospital sector in recent years. However, the organizational enforcement for acute pain management in nonsurgical areas is not adequate yet, compared to the perioperative care. In all hospitals modern medication and invasive techniques are widely available.

[The hospital emergency plan]

STRUCTURE

The hospital emergency plan consists of a basic plan and an appendix. The basic plan deals with the general aspects of emergency operation and the special aspects of external and internal emergencies. The appendix contains special instructions, e.g., emergency action orders, staff alert lists, material lists, and situation plans.

CONTENT AND IMPLEMENTATION

External emergencies (e.g., mass casualty incidents) and internal emergencies (e.g., fire and other environmental threats) should be regarded. Once a defined experienced physician decides to activate the emergency plan, the hospital changes from routine to emergency service. Due to its security significance, the emergency plan should be regarded as confidential.

MANDATORY REQUIREMENTS

A two-tier chain of command is implemented: the hospital staff deals with administrational and organizational aspects, whereas the subsequent medical staff is in charge of immediate patient care. Repeated updating and exercises are necessary. Furthermore, a basic logistic autonomy of the hospital is essential.

[Care concepts in mass casualty incidents and disasters. Concept for primary care clinic]

BACKGROUND

Patient care in mass casualty incidents and disaster strongly demand a joint approach of all preclinical and clinical forces.

OBJECTIVE

Special emphasis must be placed on immediate triage, establishment and preservation of transportability of high-risk patients and their clinical treatment as soon as possible. During limited mass casualties, the preclinical rescue station additionally serves as a buffer for patients, whereby in case of disaster, the focus on transportation of high-risk patients is imperative.

DISCUSSION AND CONCLUSION

Primary care hospitals are a decisive part in the chain of medical supply and are confronted with great challenges, which demand detailed emergency plans and also repeated exercises. In planning and exercises, special attention should be given to the cooperation with the fire department and other medical services.

[Pain therapy in emergency medicine. Focus on emergency admissions]

With a prevalence of 50-80 % pain is one of the main symptoms of emergency admission patients worldwide; however, study results demonstrate that only 30-50 % of patients receive adequate analgesia. Therefore, in the USA quality indicators have been established by the Centers for Medicare & Medicaid Services (CMS) since 2010 within the framework of quality assurance of emergency admissions, e.g. the time window until the start of pain therapy. Despite the prescribed pain evaluation as part of many existing triage systems, e.g. the Manchester triage system (MTS), emergency severity index (ESI), Australasian triage scale (ATS), Canadian triage and acuity scale (CATS), in most emergency rooms there is no standardized, documented pain assessment and pain intensity is documented by using the appropriate pain scales in only 30 % of cases. Lack of knowledge and training and lack of awareness by the nursing and medical staff regarding pain perception and management represent the main causal factors. Studies on the situation of pain therapy in German emergency departments are not currently available. Due to the increasing number of central emergency departments and interdisciplinary teams of physicians and nurses, it seems sensible to introduce interdisciplinary standards of treatment to achieve the greatest possible safety in the use of analgesics in the emergency room. It is important to incorporate the experiences of the various clinical departments in the standards. This article aims to provide an overview of the situation in pain management in emergency departments and to serve as a basis for recommendations for pain therapy in German emergency departments. This article particularly discusses the possibilities of pain evaluation, treatment options with various medications and under specific conditions, e.g. for children, pregnant women or the elderly or alternative ways of pain management.

Cross-over evaluation of electrically induced pain and hyperalgesia

Background

Anewexperimental protocol of electrically induced pain and hyperalgesia was established to examine orally administered drugs. In a randomized, double-blind, placebo-controlled cross-over study this experimental protocol was used to assess the effects of paracetamol.

Methods

Twenty-four subjects were enrolled in this study. The magnitude of pain, axon reflex flare, and areas of pin-prick hyperalgesia and touch-evoked allodynia were assessed in two consecutive sessions; prior to, and 2 h after drug administration. This protocol was repeated after 1 week. Subjects were randomized to receive either paracetamol (2 g) or a placebo.

Results

In comparison to the placebo arm there were no significant effects of paracetamol on pain, hyperalgesia, allodynia, or axon reflex flare. Pain and flare responses were highly reproducible on the same day (r = 0.77 and r = 0.79, respectively), and after 1 week (r = 0.6 and r = 0.71, respectively). The correlation between areas of hyperalgesia and allodynia was, however, significantly improved when the protocol was repeated on the same day (r = 0.8 and r = 0.75), as opposed to after a week (r = 0.54 and r = 0.53).

Discussion

The electrical pain model is a well established method for the assessment of intravenously applied analgesics. In order to assess effects of orally applied drugs the model had to be modified: for the assessment of hyperalgesia and allodynia a protocol repeating the model within 1 day proved to have advantages over repetition after 1 week.

Recovery of fibrinogen after administration of fibrinogen concentrate to patients with severe bleeding after cardiopulmonary bypass surgery

BACKGROUND

Normalization of plasma fibrinogen levels may be associated with satisfactory haemostasis and reduced bleeding. The aim of this retrospective study was to assess fibrinogen recovery parameters after administration of fibrinogen concentrate (Haemocomplettan P) to patients with diffuse bleeding in cardiovascular surgery. Data on transfusion and patient outcomes were also collected.

METHODS

Patient characteristic and clinical data were obtained from patient records.

RESULTS

of the thromboelastometry (FIBTEM)and of the standard coagulation tests, including plasma fibrinogen level, measured before surgery, before and after haemostatic therapy, and on the following day, were retrieved from laboratory records. Results Thirty-nine patients receiving fibrinogen concentrate for diffuse bleeding requiring haemostatic therapy after cardiopulmonary bypass were identified. The mean fibrinogen concentrate dose administered was 6.5 g. The mean fibrinogen level increased from 1.9 to 3.6 g litre(-1) (mean increment of 0.28 g litre(-1) per gram of concentrate administered); maximum clot firmness increased from 10 to 21 mm. The mean fibrinogen increase was 2.29 (sd 0.7) mg dl(-1) per mg kg(-1) bodyweight of concentrate administered. Thirty-five patients received no transfusion of fresh-frozen plasma (FFP) or platelet concentrate after receiving fibrinogen concentrate; the remaining four patients received platelet concentrate intraoperatively. Eleven patients received platelets, FFP, or both during the first postoperative day. No venous thromboses, arterial ischaemic events, or deaths were registered during hospitalization.

CONCLUSIONS

In this retrospective study, fibrinogen concentrate was effective in increasing plasma fibrinogen level, and contributed to the correction of bleeding after cardiovascular surgery.

[German Refined-Diagnosis Related Groups 2008 version. What is new for anaesthesia and intensive care medicine?]

The present article reviews improvements in the 2008 version of the German Refined - Diagnosis Related Groups (G-DRG) which are relevant for anaesthesia and intensive care medicine. The focal points of further developments and the data base of the updated DRG version are presented. The efforts of the InEK, the institution which is responsible for the design and development of the G-DRG system, to provide a transparent system driven by rules are also explained, followed by a description of changes in coding of diagnoses (e.g. new diagnosis codes, revised complication and comorbidity level matrix, new specifications of individual diagnosis-related groups such as acute paraplegia) and procedures (e.g. new procedure codes, modifications for complex procedures). Furthermore, some new developments concerning the functions "complicating procedure" (increase in number of G-DRGs concerned and enlarged coverage of complex intensive care procedures) as well as changes in the demographic attribute "mechanical ventilation" (modification of G-DRGs for prolonged mechanical ventilation) are discussed. Finally, the legal requirements for supplemental revenues in 2008 (e.g. new additions, movements between different catalogues of services, transitions from the catalogue of innovative diagnostic and therapeutic methods to the official catalogue) are updated. The present contribution is an update of previous articles on this topic published in this journal in 2007. Therefore, knowledge of these previous publications is a prerequisite for the understanding of the current article. Readers who are not familiar with the complex material should refer to the publications from 2007.

Effects of oral pregabalin and aprepitant on pain and central sensitization in the electrical hyperalgesia model in human volunteers †

BACKGROUND

Central sensitization is an important mechanism of neuropathic pain; its human models could be useful for early detection of efficacy of novel treatments. The electrical hyperalgesia model invokes central sensitization by repetitive stimulation of the skin. To assess its predictive value, we have investigated pregabalin, a standard neuropathic pain treatment, and aprepitant, an NK(1) antagonist, as an example of a drug class active in animal models but not in neuropathic pain patients. Furthermore, we explored if combinations of either of these drugs with the COX-2 inhibitor parecoxib could improve its efficacy.

METHODS

This was a double-blind, two-period, placebo-controlled study using incomplete block design. Thirty-two healthy volunteers received either oral pregabalin (titrated to 300 mg) or aprepitant (titrated to 320 mg), or matching placebo over 6 days before testing. Sensitization was assessed over 3 h; at 2 h, subjects received either parecoxib (40 mg) or saline i.v.

RESULTS

Pregabalin significantly reduced the areas of punctate mechanical hyperalgesia and dynamic touch allodynia vs placebo (both P < 0.0001); no significant reduction in the area of hyperalgesia or allodynia vs placebo was observed with aprepitant. In the pregabalin + parecoxib treated group, the area of allodynia was significantly reduced (P < 0.0001) and the area of hyperalgesia insignificantly attenuated (P = 0.09) vs placebo + parecoxib; no efficacy improvement was observed with aprepitant + parecoxib.

CONCLUSIONS

The model can serve to predict analgesic efficacy in early human development and investigate the mechanism of action. The model could also be used to explore efficacy of analgesic combinations to provide a rationale for patient studies.

[Preoperative pain training. No influence on postoperative pain perception in patients undergoing cardiac surgery]

BACKGROUND

The present research was performed to investigate the influence of preoperative information on pain given by the nursing staff on postoperative pain perception in patients.

METHODS

A randomized controlled interventional study was conducted in 93 patients undergoing cardiac surgery at the University Hospital Erlangen. One day before the surgery all participants were evaluated using the Eysenck Personality Questionnaire, patients of the treatment group were additionally trained by a member of the nursing staff in pain behaviour. After discharge from the intensive care unit the pain experience of the patients was evaluated using standardized questionnaires.

RESULTS

Of the 93 patients, 73 finished the study protocol and were analyzed. The pain experience was not significantly different between the two study groups. Patients with increased levels of neuroticism (characterized by emotional lability) regardless of study group more frequently reported pain values above 3/10.

CONCLUSION

No significant modulation of postoperative pain experience was achieved by preoperative information on pain. However, it cannot be ruled out that this intervention, particularly in view of the reduction in anxiety, may form a significant element of perioperative pain management.

Opioidvermittelte Analgesie und Hyperalgesie

Opioids are frequently used for the treatment of moderate to severe acute and chronic pain. However, clinical evidence suggests that opioids can elicit increased sensitivity to noxious stimuli suggesting that administration of opioids can activate both, pain inhibitory and pain facilitatory systems. Acute receptor desensitization via uncoupling of the receptor from G proteins, upregulation of the cAMP pathway, activation of the N-methyl-D-aspartate (NMDA) receptor system and descending facilitation have been proposed as potential mechanisms underlying opioid-induced hyperalgesia. The tolerance results from a pain sensitization process more than from a decrease in the opioid effectiveness. Opioid-induced hyperalgesia and tolerance are observed both in animal and human experimental models. Brief exposures to mu-receptor agonists induce long-lasting hyperalgesic effects for days. Furthermore, the prolonged use of opioids in patients often requires increasing doses and may be accompanied by the development of abnormal pain. Successful strategies that may decrease or prevent opioid-induced hyperalgesia include the concomitant administration of drugs such as NMDA antagonists, alpha(2)-agonists, or nonsteroidal anti-inflammatory drugs (NSAID), opioid rotation, or combinations of opioids with different receptor selectivity.

[Opioid-induced hyperalgesia. Pathophysiology and clinical relevance]

Opioids are the drugs of choice for the treatment of moderate to severe acute and chronic pain. However, clinical evidence suggests that opioids can elicit increased sensitivity to noxious stimuli suggesting that administration of opioids can activate both pain inhibitory and pain facilitatory systems. Acute receptor desensitization via uncoupling of the receptor from G-proteins, up-regulation of the cAMP pathway, activation of the N-methyl-D-aspartate (NMDA) receptor system, as well as descending facilitation, have been proposed as potential mechanisms underlying opioid-induced hyperalgesia. Numerous reports exist demonstrating that opioid-induced hyperalgesia is observed both in animal and human experimental models. Brief exposures to micro-receptor agonists induce long-lasting hyperalgesic effects for days, which might by reflected by clinical observations that large doses of intraoperative micro-receptor agonists increased postoperative pain and morphine consumption. Furthermore, the prolonged use of opioids in patients often requires increasing doses and may be accompanied by the development of abnormal pain. Successful strategies that may decrease or prevent opioid-induced hyperalgesia include the concomitant administration of drugs like NMDA-antagonists, alpha(2)-agonists, or non-steroidal anti-inflammatory drugs (NSAIDs), opioid rotation or combinations of opioids with different receptor selectivity.

Increased numbers of opioid expressing inflammatory cells do not affect intra-articular morphine analgesia

BACKGROUND

Both locally expressed beta-endorphin (END) and low doses of morphine relieve pain within inflamed knee joints. Here we examined whether enhanced inflammation and END expression within the synovial tissue of patients undergoing arthroscopic knee surgery might shift the analgesic dose-response curve of intra-articular (i.a.) morphine.

METHODS

Following IRB approval and informed consent, patients were randomly assigned to the following i.a. treatments at the end of surgery: group I (n=39), isotonic saline; group II (n=40), 1 mg morphine hydrochloride; group III (n=48), 2 mg morphine hydrochloride; group IV (n=39), 4 mg morphine hydrochloride. Postoperative pain intensity was assessed by the visual analogue scale (VAS), by the time to first analgesic request and by the supplemental piritramide consumption. Synovial specimens from each patient were stained for the presence of inflammatory cells and END and were discriminated into groups with low versus high numbers of these cells. Differences between groups were statistically analyzed by chi(2), anova and mancova where appropiate.

RESULTS

Patient characteristics and VAS scores did not differ between groups. Total postoperative piritramide consumption decreased and the time to first analgesic request increased significantly with increasing doses of i.a. morphine (P<0.05, anova and linear regression). These dose-response relationships were not different between patients with low versus high numbers of inflammatory and END-containing synovial cells (P>0.05, mancova).

CONCLUSIONS

The dose-response relationship of i.a. morphine analgesia is not shifted by enhanced inflammation and END expression within synovial tissue. Thus, the presence of END within inflamed synovial tissue does not seem to interfere with i.a. morphine analgesia.

[Differentiation of peripheral and central hyperalgesic effects of systemic procaine]

OBJECTIVE

The aim of this study was to differentiate between the peripheral and central analgesic and antihyperalgesic properties of systemic procaine hydrochloride in standardized human pain models.

METHOD

Subcutaneous injections of either 150 mg procaine hydrochloride or saline solution were administered at intervals of 2 weeks on a randomized and double blind basis. During the 90-min infusion and subsequent 60-min monitoring periods, touch sensitivity was determined and in addition two experimental hyperalgesic models were analyzed.

RESULTS

While touch sensitivity was not affected by procaine hydrochloride, development of primary mechanical hyperalgesia was significantly reduced.

CONCLUSION

The concentration of procaine hydrochloride used in our experiment elicited peripheral antihyperalgesic effects without central venous side effects. These results can account for the clinical effect of low-dose procaine hydrochloride in pain conditions exhibiting pronounced hyperalgesia.

Different lipid profiles as constituencies of liquid formula diets do not influence pain perception and the efficacy of opioids in a human model of acute pain and hyperalgesia

Nutritional support and pain control by medication are often used concomitantly, but interactions are hardly investigated. A randomised, double-blind, cross-over study in ten right-handed volunteers was performed evaluating the influence of cholecystokinin (CCK)-excretion on the perception of pain in a standardised model. CCK-excretion was induced by a liquid formula diet with either long- or medium-chain triglycerides (LCT, MCT). Plasma samples were drawn over a 60 min period in 15-min intervals and CCK and somatostatin (SMS) were measured by radioimmunoassay (RIA). Gastric emptying was evaluated by C-13-breath testing. Transcutaneous electrical stimulation at a high current density (5 Hz, 70.1+/-5.8 mA) was used to provoke acute pain and stable areas of secondary mechanical hyperalgesia and pinprick allodynia for 2 h. Ongoing pain ratings as well as extension of pinprick-hyperalgesia and allodynia were compared between both liquid formula diets. In a second series of experiments, alfentanil (4.1+/-0.5 mg) was administered for 90 min using target-controlled infusions and measurements were performed as stated above. Oral administration of LCT as well as MCT may lead to different CCK blood levels, but we found no evidence for CCK-induced effects on pain sensation, touch-evoked allodynia, secondary hyperalgesia or morphine-induced anti-nociception in humans. In our studies, liquid formula diets did not influence acute pain perception or the efficacy of opioids in a human model of pain.

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings

BACKGROUND AND OBJECTIVE

Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction.

METHODS

Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH.

RESULTS

In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant).

CONCLUSIONS

The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Blood flow increase in the human lip after high-intensity tooth stimulation is not based on cholinergic mechanisms

The purpose of this study was to investigate whether parasympathetic cholinergic pathways are involved in the regulation of orofacial blood flow. The effect of atropin (1 mg, iv.) on blood flow responses in the lower lip, nose and hand during painful tooth stimulation was studied in healthy human subjects (n=8). In all subjects, tooth stimulation caused a long lasting vasodilatation in the lower lip. During stimulation there was a transient elevation in heart rate (HR) and blood pressure (BP) concomitantly with a blood flow decrease in the finger and nose. With atropin, the pain-induced HR and BP elevations and blood flow reductions in the nose and finger were decreased. However, the pain-induced blood flow increase in the lip was not changed. This study indicates that the tooth stimulation-induced vasodilatation in the lip is not based on parasympathetic cholinergic mechanisms.

Different patterns of mast cell activation by muscle relaxants in human skin

BACKGROUND

Activation of mast cells and systemic release of histamine are major side effects of intravenously administered muscle relaxants. In the current study, dermal microdialysis was used for the investigation of mast cell activation by muscle relaxants. Dermal microdialysis enabled simultaneous assessment of mediator release, vascular reactions, and sensory effects induced by intradermal application of muscle relaxants without systemic side effects.

METHODS

Succinylcholine, the isoquinolines cisatracurium, atracurium, and mivacurium, and the steroids pancuronium, vecuronium, rocuronium, and rapacuronium were tested in human volunteers (n = 6 each). After intradermal insertion of microdialysis capillaries (0.4 mm diameter, cutoff 3,000 kd) and a 60-min equilibration period, the muscle relaxants were delivered via the capillaries for 30 min, followed by a 30-min washout period. Dialysate was sampled at 15-min intervals, and histamine, mast cell tryptase, and protein extravasation were determined. Changes in skin blood flow were measured using a laser Doppler imager. Potency and efficacy were derived from nonlinear fittings of the dose-response curves.

RESULTS

For succinylcholine and the isoquinolines, dose-response curves for the vascular and sensory effects paralleled the histamine and tryptase release. In contrast, aminosteroids evoked a rapid histamine release that was accompanied by a delayed increase in tryptase.

CONCLUSIONS

Dermal microdialysis has been successfully used to simultaneously assess mediator release, vascular reactions, and sensory effects. The different pattern of tryptase release by isoquinolines and aminosteroids suggests different mechanisms of mast cell activation.

Interactions of histamine and bradykinin on polymodal C-fibres in isolated rat skin

Patients suffering from pruritus due to atopic dermatitis show, in asymptomatic skin, reduced itch and flare responses to histamine, the major pruritogenic mediator. We hypothesized that this apparent loss in histamine sensitivity may be overcompensated in inflamed skin and investigated the interactions between histamine and bradykinin, the major inflammatory mediator. The studies were performed using the isolated rat skin-nerve preparation. Forty-two fibres were tested following four different experimental protocols. After characterization of the sensory properties, six fibres were treated repetitively with histamine (HIS1, HIS2) to exclude the possibility that the responses (spikes/min) increase simply by repetition. In 12 other units, histamine (HIS1) was followed by a wash-out period prior to bradykinin (BK) stimulation; in another 12 units, BK followed immediately after HIS1. A further 12 fibres were examined without preceding heat stimulation in order to avoid possible sensitization. If BK was administered after a wash-out period following HIS1, the BK responses were significantly higher than the HIS1 response. The BK response showed a peak discharge which was absent if BK followed directly upon HIS1. If HIS2 was applied directly following BK, the induced discharge was significantly larger than the first histamine response and not different from the BK response, whereas a washout period before HIS2 abolished the sensitizing effect of previous BK.A unidirectional sensitization by previous bradykinin or heat stimulation on the histamine responsiveness of polymodal nociceptors has been demonstrated. If 'itch fibres' in humans were subject to similar interactions of histamine with inflammatory mediators, this may compensate for a down-regulation of histamine receptors in eczematic skin and possibly account for the pruritus.

A new model of electrically evoked pain and hyperalgesia in human skin: the effects of intravenous alfentanil, S(+)-ketamine, and lidocaine

BACKGROUND

The authors used the analgesics alfentanil, S(+)-ketamine, and systemic lidocaine to examine a new human model of experimental pain and hyperalgesia.

METHODS

Transcutaneous electrical stimulation at a high current density (5 Hz, 67.5+/-6.6 mA) was used to provoke acute pain (numeric rating scale, 5 of 10), stable areas of secondary mechanical hyperalgesia to pin prick (43.6+/-32.1 cm2), and light touch (27.5+/-16.2 cm2) for 2 h. Alfentanil, S(+)-ketamine, and lidocaine were applied for 20 min in a double-blind, placebo-controlled, crossover design in 12 subjects using target controlled infusions.

RESULTS

In the placebo session, pain ratings and areas of hyperalgesia were stable during the stimulation period, which facilitated the assessment of analgesic effects. Alfentanil effectively inhibited electrically evoked pain and reduced pin prick hyperalgesia and allodynia during its infusion. S(+)-ketamine-induced inhibition of secondary hyperalgesia was more pronounced and lasted for the whole experimental protocol. Therapeutic levels of systemic lidocaine showed only marginal analgesic effects, but lasting antihyperalgesic effects.

CONCLUSIONS

A new model of electrically induced pain and hyperalgesia was established, which enabled assessment of the time course of analgesic and antihyperalgesic effects with high temporal resolution and minimum tissue damage and which was further validated by use of common intravenous anesthetics.

[Postoperative transcutaneous electrical nerve stimulation (TENS) in shoulder surgery (randomized, double blind, placebo controlled pilot trial)]

BACKGROUND

The aim of this study was to determine whether 3 days of TENS therapy postoperatively after shoulder operations would result in better pain relief and/or reduced analgesic intake when compared to placebo.

METHOD

The study was carried out randomized, double-blind and placebo controlled. Thirty patients were randomized to two groups. The verum group received TENS SM1AKS 80 Hz 6 mA and the placebo group received TENS SM1AKS 80 Hz 0 mA. The pain was assessed pre-operatively using the Hamburg Pain Adjective List. Premedication and Anaesthesia were standardized. TENS was applied to the patients immediately postoperatively for 8 hours and then on the following days 5 times daily for 45 minutes. The effectiveness was evaluated postoperatively using a visual analogue scale (rest, activity), the Hamburg Pain Adjective List and postoperative analgesic consumption.

RESULTS

The visual analogue scale at rest and on activity showed no significant difference between the groups. Postoperative analgesic consumption of morphine hydrochloride in the first 24 hours was at time 8 hours postoperative significantly and at all other time points markedly less in the verum group compared to the placebo group. The sensory secondary scale score of the "Hamburg Pain Adjective List" was significantly lower postoperatively compared to preoperatively in the verum group.

CONCLUSION

We were able to show in this study that TENS applied postoperatively after shoulder surgery clearly reduced analgesic consumption in the first 72 hours. Furthermore there was a significant difference in the pain scores using the "Hamburg Pain Adjective List" in favour of the verum group. TENS applied postoperatively is a effective, simple modality with few side-effects.

Efficacy of peripheral morphine analgesia in inflamed, non-inflamed and perineural tissue of dental surgery patients

In a clinical model of dental pain, the analgesic efficacy of local morphine treatment was examined under three different conditions. Patients undergoing dental surgery were randomly assigned to an injection of local anesthetic (articaine) plus 1 mg morphine either into inflamed (n = 14; trial 1) or non-inflamed (n = 24; trial 2) submucous tissue or perineurally n = 19; trial 3). Patients in the control group for each condition (n = 13, trial 1; n = 26, trial 2; n = 16, trial 3) received articaine plus saline. Postoperative pain intensity was assessed by the visual analog scale (VAS) and numeric rating scale (NRS) at 0, 2, 4, 6, 8, 10, 12, 16, 20, and 24 h. In addition, patients recorded the occurrence of side effects and the supplemental consumption of diclofenac. Immediately after the operation, pain scores were reduced to a similar extent in all groups, most likely due to the local anesthetic effect. Thereafter, pain scores and supplemental consumption of diclofenac were significantly lower in patients receiving 1 mg morphine into inflamed submucous tissue than in the control group for up to 24 h. Patients receiving 1 mg morphine into non-inflamed tissue or perineurally did not show any further reduction in pain scores compared to each control group. Our results show in patients undergoing dental surgery that injection of 1 mg of morphine into inflamed tissue results in significant and prolonged postoperative analgesia, whereas administration into non-inflamed tissue or perineurally is not effective. Thus, consistent with experimental studies, the requirement of an inflammatory process for the occurrence of peripheral opioid effects is also found in the clinical setting.

[Monitoring of patient-controlled analgesia by the nursing staff]

OBJECTIVE

Patient-controlled analgesia (PCA) is employed successfully on surgical wards. Continuous monitoring is important for the safety of the patient and the efficiency of this form of pain therapy. In the study we evaluated the regularity and completeness of monitoring data which had been collected by the nursing staff on the surgical wards.

METHODS

Data on pain intensity, vital signs, and side effects were collected. Additionally, in the case of epidural analgesia, sensory and motor function were tested. In the first four hours after starting the PCA-pump, the nursing staff was instructed to document this data hourly (phase I), followed by a two hour interval until 8 am the next day (phase II). In general, monitoring was continued every four hours up to the discontinuation of the PCA; whereas in our study only forty hours (10 measurements) were included (phase III). Documentation protocols of 637 patients were evaluated and tested for the completeness of the data.

RESULTS

In phase I, the data of 128 patients (20%) were complete. In 173 patients (27%) less than 50% of the data were documented. During phase II, only in 98 patients (15%) the data collection was complete. In 237 patients (37%) less than 50% of the measurements were determined. In phase III, in 205 patients (32%) all measurements, and in 104 patients (16%) less than 50% of the measurements were documented.

CONCLUSION

Complications during PCA become manifest mainly during the first hours after starting the PCA-pump. Especially during these phases, documentation was found to be quite poor. This underlines the importance of an intense cooperation between acute-pain service and nursing staff with periodical training of the staff.

[Management of postoperative pain in children]

TREATMENT OF PAIN: Undertreatment of postoperative pain in children is a problem in clinical practice. This is due to a lack of both knowledge about age-specific aspects of physiology and pharmacology, and routine pain assessment. For example, the fear of side-effects prevents the adequate usage of opioids. It is of major importance to select a route of drug administration where the child feels comfortable with (avoid intramuscular injections). NON-OPIOID ANALGESICS: Non-opioid analgesics are recommended for basic pain treatment after minor surgical procedures. Instead of using the whole multitude of drugs available, the doctor should stick to those drugs he is familiar with (acetaminophen, ibuprofen, diclofenac, dipyrone).

OPIOIDS

Opioid usage requires individual dose titration and careful monitoring of side-effects (respiratory monitoring, sedation score). The strong opioids piritramide and morphine may advantageously be administered as either continuous, or patient-controlled iv- infusion (PCA).

FORMS OF THERAPY

In addition to infiltration anesthesia, intraoperatively applied nerve blocks provide excellent pain relief. Epidural analgesia with local anesthetics and/or opioids via a thoracic or lumbar epidural catheter is a therapeutic option after thoracic or abdominal surgery, or after extensive orthopedic or urological interventions. Adjuvant analgesics and nonpharmacologic interventions, i. e. transcutaneous electrical nerve stimulation (TENS), are primarily indicated in patients suffering from neuropathic pain.

CONCLUSION

The establishment of pain services and the comprehensive education of both the nursing and the medical staff should help to improve postoperative pediatric pain therapy.

Retrobulbar versus systemic application of morphine during titratable regional anesthesia via retrobulbar catheter in intraocular surgery

IMPLICATIONS

We investigated the effects of morphine on postoperative pain in patients undergoing intraocular surgery using a new indwelling catheter. Although morphine produced central analgesic effects, there was no evidence for the involvement of peripheral opioid receptors in the modulation of ocular pain.