Pre-incisional epidural ropivacaine, sufentanil, clonidine, and (S)+-ketamine does not provide pre-emptive analgesia in patients undergoing major pancreatic surgery

BACKGROUND

The concept of pre-emptive analgesia remains controversial. This prospective, randomized, and double-blind study compared epidural administration of ropivacaine 2 mg ml(-1), sufentanil 0.5 microg ml(-1), clonidine 3 microg ml(-1), and S(+)-ketamine 0.25 mg ml(-1) (study solution) given before incision with the same combination started at the end of the operation.

METHODS

After testing the stability of the solution using high performance liquid chromatography (HPLC) and examining 12 patients for possible side-effects in comparison with the epidural infusion of ropivacaine 2 mg ml(-1) and sufentanil 0.5 microg ml(-1), 30 patients undergoing major pancreatic surgery were recruited into the study. Before induction of anaesthesia, an epidural catheter was inserted (TH6-8). Patients in Group 1 received a bolus of 8 ml followed by a continuous infusion (8 ml h(-1)) of the study solution before induction of anaesthesia. In Group 2, patients received the same volume of saline before operation, the study solution was started at the end of surgery. After operation, the infusion was maintained for at least 96 h using a patient-controlled epidural analgesia (PCEA) pump in both groups. Patients were evaluated up to the seventh postoperative day for pain and side-effects.

RESULTS

Visual analogue scale (VAS) values at rest were as follows: G1 vs G2: 24 h, 19 (sd 23) vs 6 (13); 48 h, 4 (10) vs 11 (21); and 72 h, 12 (22) vs 13 (21). VAS values during coughing and mobilization were also comparable. Total volume of epidural infusion was 904 (114) ml in G1 vs 892 (154) ml in G2. The incidence of side-effects (nausea, vomiting, and motor block) was low and not different between the groups.

CONCLUSIONS

Pre-incisional epidural analgesic infusion did not provide pre-emptive analgesia compared with administration started at the end of surgery, but both groups had low pain scores.

Elevated plasma concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine predict adverse events in patients undergoing noncardiac surgery

OBJECTIVE

In patients with cardiovascular disease or organ failure, elevated plasma concentrations of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) are associated with an increased risk of future cardiovascular events. We aimed to investigate elevated plasma ADMA concentrations as a prospective risk marker for adverse events in patients undergoing noncardiac surgery.

DESIGN

Prospective observational study.

SETTING

Two tertiary care centers.

PATIENTS

Four hundred and two patients scheduled for elective noncardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were followed for 30 days after surgery for a predefined composite end point (death, myocardial infarction/acute coronary syndrome, acute heart failure, severe arrhythmia, embolism, or thrombosis). Plasma ADMA concentrations at baseline were determined by high-performance liquid chromatography. ADMA was only weakly (-0.2 < tau < 0.2) correlated with other risk markers and risk scores. In univariate logistic regression, per 0.1-micromol/L increment in plasma ADMA concentration, the odds ratio to experience the primary end point increased by 1.26 (95% confidence interval 1.10-1.45, p = .001). In a multivariate logistic regression model adjusting for age, gender, current smoking, plasma creatinine, hypertension, diabetes, ischemic heart disease, highly sensitive C-reactive protein, revised cardiac risk index, type of surgery, high-risk surgery, ASA class, and study center, ADMA was found to be an independent risk marker. The odds ratio to experience the primary end point was 1.33 (95% confidence interval 1.12-1.59, p = .001) per 0.1-micromol/L increase in the plasma ADMA concentration.

CONCLUSIONS

Elevated plasma ADMA concentrations are independently associated with a higher risk for adverse events in the peri- and postoperative periods.

[Abdominal compartment syndrome. A still underestimated problem?]

The abdominal compartment syndrome (ACS) is a life threatening disorder in critically ill patients caused by rapidly decreasing intra-abdominal pressure (IAP) > 12 mm Hg, which may result in multiple organ dysfunctions with a possibly fatal outcome. Under various causes for the development of an ACS, pelvic trauma, volume resuscitation after severe hemorrhage and reperfusion after aortic aneurysm repair as well as intra-abdominal packing figure at the first place. An increased BMI is a risk factor for patients to suffer from ACS. In addition, excessive volume requirement and significantly increasing airway pressures within the first 24 hrs after admission in the ICU are indicators for an impending ACS. Increased IAP causes venous stasis and arterial malperfusion of all intra- and extra-abdominal organs thus resulting in ischemia, hypoxia and necrosis. In parallel, respiratory, cardiocirculatory, renal, intestinal and cerebral decompensation can be registered. Final multiorgan failure has a mortality around 60-70 %. Timely diagnosis of ACS remains sometimes difficult in spite of clinical indicators such as increased airway pressure, hypoxia, oliguria, shock and acidosis. For the early recognition of intra-abdominal hypertension repetitive measurement of the intra-vesical pressure (> 20 mm Hg) can be helpful. Besides intensive care treatment with artificial ventilation, circulatory support with volume and catecholamines, the decision for a prompt abdominal decompression and open abdominal treatment is life-saving and can preserve further functional damage to vital organ systems.

[Combined spinal-epidural anaesthesia for pain relief in obstetric patients]

Besides epidural analgesia combined spinal-epidural anaesthesia (CSE) is one of the favourite techniques of regional anaesthesia for pain relief in obstetric patients. CSE combines the advantage of spinal anaesthesia, e.g. rapid onset and reliable effect, with the advantage of continuous epidural anaesthesia, e.g. titration of analgesics and prolongation. While subarachnoid injection of solely opioids provides fast pain relief for nearly 2 hrs in the first stage of labour with an opportunity of ambulation for the parturient ("walking epidural"), the subarachnoid injection of a combination of low doses of opoids and local anaesthetics provides profound analgesia with minor motor blocking side effects for 1-2 hrs in the second stage of labour.

Epiduralanästhesie: Schritt für Schritt zum Erfolg

Besides pain management in obstetric patients epidural anaesthesia plays a major role in the perioperative setting. Especially the technique of thoracic epidural anaesthesia (TEA) provides better postoperative analgesia when compared with systemic pain therapy. TEA is associated with improved outcome in high-risk patients and patients undergoing extensive surgery. An acute pain management service is required to guarantee high effectiveness and a low complication rate. TEA is an important part of a multimodal perioperative concept, especially in fast-track surgery, which means advantages for patients outcome and hospitals economics.

Entfernung eines Epiduralkatheters unter antithrombotischer Therapie

A rare though extremely harmful complication in neuraxial anaesthesia is an epidural hematoma which can be associated with deleterious consequences for the patient, e. g. persistent paraplegia. The risk of epidural haematomas after neuraxial blockade is dependent on abnormal anatomy of the spine, difficult and multiple punctures and coagulation disorders. Especially when patients undergo therapy with anticoagulants like low molecular heparin or platelet inhibitors (tyclopidine) or a combination of them, the indication for neuraxial blockade must strictly outweigh risk of spinal bleeding. In this context, the precautions and contraindications are the same for spinal puncture and catheter insertion as for catheter removal. We describe the case of a patient who underwent emergency coronary angioplasty in combination with coronary stent implantation due to acute postoperative myocardial infarction following knee replacement in continuous epidural anaesthesia. Under the symptoms of a beginning local infection at the puncture site the epidural catheter had to be removed in spite of ongoing antithrombotic therapy. A possible management of such cases is discussed with regard to risk minimization.

Cost drivers in anesthesia: manpower, technique and other factors

PURPOSE OF REVIEW

This article reviews the recent literature on cost drivers in anesthesia with respect to staff, techniques and drug costs, and with special focus on anesthesia workflow in the postanesthesia care unit. Moreover, the costs of post-operative pain management provided by an acute pain service are highlighted.

RECENT FINDINGS

Staff costs represent the main contributor to anesthesia costs in all studies. Therefore, many studies address the reduction of personnel costs, e.g. by using fast-tracking procedures which allow the patients to bypass the postanesthesia care unit. However, postanesthesia care unit bypassing and replacement of anesthesiologists by certified anesthesia nurses were not able to significantly decrease anesthesia costs. If anesthesiologists are reimbursed by surgically controlled time, this time is the main determinator for anesthesia costs and should be carefully monitored. Regional anesthesia techniques can help to reduce costs in the ambulatory setting because of reduced post-operative side-effects and earlier home readiness of the patients. Low gas flow and modern electroencephalographic monitoring can contribute to decreased drug-related costs. Acute pain services are mainly run by anesthesia staff thus increasing the costs in anesthesia departments. However, an acute pain service can reduce costs of surgical procedures significantly.

SUMMARY

Clear definition of the meaning of cost drivers and of criteria which allow assessment of patients' condition, and peri-operative standard operating procedures are warranted to ensure comparability of economic data in anesthesia.

Kontinuierliche interscalenäre Plexusblockade bei einem dreijährigen Kind nach Armamputation - Ein Fallbericht

Amputations of extremities, especially in the childhood, impose high demands on the perioperative management. Apart from the intraoperative care of these children, the postoperative pain therapy has to do one's utmost in the avoidance of the development of phantom limb pain, which can, especially in the childhood, be associated with far reaching psychological consequences. We report the case of a 3-year old boy who had to undergo exarticualtion of his left arm due to an osteosarcoma of the humerus. The perioperative pain management was performed by a preoperatively placed interscalene catheter and infusion of 0.2 % ropivacaine. Within the first six days postoperatively complete pain relief could be ensured with this analgetic regimen.

Forderungen und Erwartungen an einen optimalen Volumenersatz

A volume replacement should compensate a reduction in the intravascular volume and counteract a hypovolemia so that hemodynamics and vital functions can be maintained. For this therapy, a physiologically-based solution comprising both osmotically and colloid osmotically active components should be administered. A consensus is proposed for this purpose which takes into consideration the following aspects: The optimum colloid, the questionable use of albumin, the physiological electrolyte pattern encompassing sodium, potassium, chloride and phosphate and their contributions to osmolality, an eventual addition of glucose, the physiological acid-base status with bicarbonate or alternately with metabolisable anions, and the importance of a clear declaration of all ingredients. The consensus distinguishes between compulsory requirements derived from evidence-based medicine and physiological data and the potential expectations of an optimal volume replacement, including well-grounded wishes and aspirations for the future.

Reduction of Anesthesia Process Times After the Introduction of an Internal Transfer Pricing System for Anesthesia Services

To improve operating room workflow, an internal transfer pricing system (ITPS) for anesthesia services was introduced in our hospital in 2001. The basic principle of the ITPS is that the department of anesthesia receives reimbursement only for the surgically controlled time, not for anesthesia-controlled time (ACT). A reduction in anesthesia process times is therefore beneficial for the anesthesia department. In this study, we analyzed the ACT (with its parts: preparation before induction, induction, extubation, and recovery room transfer) for 3 yr before and 3 yr after the introduction of the ITPS in 55,776 cases. Furthermore, the anesthesia cases were subsegmented into 10 different anesthesia techniques, and the process times were studied. The average total ACT was reduced from 40.4 +/- 23.5 min in 1998 to 34.3 +/- 21.7 min in 2003. The main effect came from reductions in anesthesia preparation time and recovery room transfer time, whereas induction and extubation time changed little. A significant reduction in average ACT was seen in 7 of 10 analyzed anesthesia techniques, ranging from 4 to 18 min. We conclude that transfer pricing of anesthesia services based on the surgically controlled time can be a successful approach to reduce anesthesia process times.

A new oxygen transport agent

Modern highly purified and chemically modified hemoglobin-based oxygen carriers (HBOC) are free of significant side effects on kidneys and coagulation, and they do not possess ABO antigens, allowing transfusion without knowledge of the respective blood group. Even at room air oxygen concentrations HBOC can compensate for intravascular volume deficits in hemorrhagic shock, including restoration of colloid osmotic pressure and organ perfusion, and deliver oxygen to organs and tissues during nearly complete blood exchange. In animal experiments and clinical trials all HBOC showed a vasoconstrictive side-effect which is mainly caused by nitric oxide scavenging, and to a lesser extent by reactive vasoconstriction because of precapillary oxygen off-loading. The study by Bjorkholm in this issue of the journal (see page 505) investigates the application of a moderate dose of the newly designed HBOC, MP4, in volunteers. MP4 has a high molecular size and a very low p50 resulting in a high oxygen affinity thus avoiding significant (pre)capillary oxygen off-loading. No significant rises in blood pressure or major laboratory abnormalities were seen after MP4 infusion. This new HBOC may be applicable in patients as a red blood substitute where vasoconstriction must be avoided. In addition, poststenotic tissue oxygenation might be a further indication. However, the number of treated volunteers and the infused dose of MP4 were both are very small. Therefore, one cannot draw conclusions on the safety, tolerability and efficacy of MP4 in terms of red cell replacement when large amounts of oxygen carriers are needed.

Microcirculatory function and tissue damage is improved after therapeutic injection of bovine hemoglobin in severe acute rodent pancreatitis

OBJECTIVES

Stasis of the pancreatic microcirculation initiates and aggravates acute pancreatitis. Bovine hemoglobin has been shown to improve microcirculation in acute pancreatitis if prophylactically infused 15 minutes after initiation of acute pancreatitis. The purpose of this study was to evaluate the therapeutic effectiveness of bovine hemoglobin on pancreatic microcirculation and tissue damage later in the course of experimental acute rodent pancreatitis.

METHODS

In Wistar rats, severe acute pancreatitis was induced by administration of glyco-deoxycholic-acid intraductally and cerulein intravenously. Pancreatic microcirculation was continuously monitored by intravital microscopy. Three hours after the initiation of acute pancreatitis, animals received either 0.8 mL bovine hemoglobin (Oxyglobin), hydroxyethyl starch (HES), or 2.4 mL 0.9% NaCl intravenously at random. After 6 hours, animals were killed, and histopathological damage of the pancreas was assessed using a validated histology score.

RESULTS

Pancreatic microcirculation assessed by leukocyte adherence was significantly improved by the administration of bovine hemoglobin in comparison with normal saline over time (mean difference, 51.6 +/- 9.2; P < 0.001) and HES (mean difference, 24.1 +/- 9.2; P = 0.037). This result was paralleled by decreased tissue damage in the bovine hemoglobin group as opposed to NaCl (6.75 vs. 12; range, 5.25-7.75 vs. 8.25-14; P < 0.001) and HES (6.75 vs. 9; range, 5.25-7.75 vs. 7.5-10.75; P < 0.001).

CONCLUSION

Therapeutic intravenous infusion of bovine hemoglobin improves pancreatic microcirculation and reduces pancreatic tissue damage in severe acute rodent pancreatitis but is not as effective as early (prophylactic) administration.

SNAP index and Bispectral index during different states of propofol/remifentanil anaesthesia

The accuracy of the new SNAP index with the Bispectral index (BIS) to distinguish different states of propofol/remifentanil anaesthesia was compared in 19 female patients who were undergoing minor gynaecological surgery. Comparisons of the SNAP index, BIS, spectral edge frequency, mean arterial blood pressure and heart rate were performed. The ability of all parameters to distinguish between the steps of anaesthesia -awake vs. loss of response, awake vs. anaesthesia, anaesthesia vs. first reaction and anaesthesia vs. extubation - were analysed with the prediction probability. The prediction probability to differentiate between two interesting nuances of anaesthetic states -loss of response vs. first reaction - was calculated. Only the BIS showed no overlap between the investigated steps of anaesthesia. Both the SNAP index and BIS failed to differentiate the nuances of anaesthesia. The SNAP index and BIS were superior to mean arterial blood pressure and heart rate and spectral edge frequency in distinguishing between different steps of anaesthesia with propofol and remifentanil and provided useful additional information.

A Retrospective Comparison of Costs for Regional and General Anesthesia Techniques

In this retrospective study, we compared the costs for three different regional anesthesia techniques with the costs of general anesthesia (GA). A total of 1587 anesthesia cases which were performed for orthopedic and trauma patients over a 1-yr period in a tertiary level, university hospital setting were analyzed. The anesthesia technique-related costs were determined calculating case-specific costs for personnel, supplies, and drugs. The techniques were compared on the basis of anesthesia costs and surgical procedure duration. As a result, we found that the costs per surgical minute largely depend on the surgical procedure duration. Based on the regression function, the cost advantage of spinal anesthesia over GA can be estimated to be 13% for a 50-min case, 9% for a 100-min case, and 5% for a 200-min case. The cost disadvantage of brachial plexus anesthesia over GA can be estimated to be 19% for a 50-min case, 8% in a 100-min case, and 1% for a 200-min case. We found no difference in costs between epidural and GA. We concluded that cost comparisons of anesthesia techniques largely depend on the surgical duration of the cases studied. Even in a teaching hospital setting, spinal anesthesia has economic advantages over GA. Especially for short cases, brachial plexus block is more expensive in this setting.

3. Internationales Symposium: „Autologe Transfusion - Von der Euphorie zur Ratio: Praktisches Handeln aus wissenschaftlicher Sicht” (Teil IV)Künstliche Sauerstoffträger: Hämoglobinlösungen - Stand 2004

Because of an impending shortfall of allogeneic blood products within the next decades and ongoing problems such as transfusion reactions, immunomodulating side effects and the risk of bacterial, viral and prion transmission associated with relevant costs for testing and storage of banked RBC units which, additionally, suffer from aging processes, the development of alternatives has been intensified during the last 15 years. Modern chemically modified hemoglobin-based oxygen carriers (HBOC) are free of red blood cell membrane remnants eliminating renal toxicity, and they do not possess AB0 antigens which allows transfusion without knowledge of the respective blood group of a patient. Bovine polymerized cell-free hemoglobin can be stored at room temperature for three years. In contrast to the perfluorocarbon solutions, HBOC can be applied at room air oxygen concentrations. Animal experiments have shown that HBOC can compensate for intravascular volume deficits in hemorrhagic shock, including restoration of colloid osmotic pressure and organ perfusion, and deliver oxygen to organs and tissues during nearly complete blood exchange. Chemical modifications of HBOC are able to reduce the vasoconstrictive side-effect of HBOC which is caused by NO scavenging. In spite of vasoconstriction the increased oxygen extraction in presence of HBOC in combination with the plasmatic oxygen transport provides enhanced tissue oxygenation even in post-stenotic tissues. HBOC seem to improve the diffusive oxygen transport at the microcirculatory site thus decreasing tissue damage in acute pancreatitis and the heart and brain after ischemia/reperfusion injury. Clinical studies have shown that the peri-operative use of different HBOC (Hemopure, PolyHeme, Hemolink and HemAssist) can reduce the number of allogeneic RBC units and increase the avoidance rate of allogeneic transfusion in emergency bleeding, vascular, cardiac and non-cardiac surgery. Polymerized HBOC appear to have a lower potential of side effects in comparison to intra-molecularly cross-linked preparations. However, HBOC-201 (Hemopure) is the only substance which has been licensed for the treatment of patients with acute peri-operative anemia in South Africa until now.

Comparative evaluation of the Datex-Ohmeda S/5 Entropy Module and the Bispectral Index monitor during propofol-remifentanil anesthesia

BACKGROUND

Different analytical concepts were introduced to quantify the changes of the electroencephalogram. The Datex-Ohmeda S/5 Entropy Module (Datex-Ohmeda Division, Instrumentarium Corp., Helsinki, Finland) was the first commercial monitor based on the entropy generating two indices, the state entropy (SE) and the response entropy (RE). The aim of the current study was to compare the accuracy of SE and RE with the Bispectral Index(R) monitor (BIS(R); Aspect Medical Systems, Newton, MA) during propofol-remifentanil anesthesia.

METHODS

The authors investigated 20 female patients during minor gynecologic surgery. SE, RE, BIS, mean arterial blood pressure, heart rate, and sedation level were recorded every 20 s during stepwise increase (target-controlled infusion, 0.5 microg/ml) of propofol until the patients lost response. Five minutes after loss of response, remifentanil infusion (0.4 microg . kg(-1) . min(-1)) was started. Spearman correlation coefficient and prediction probability were calculated for sedation levels with SE, RE, BIS, mean arterial blood pressure, and heart rate. The ability of the investigated parameters to distinguish between the anesthesia steps awake versus loss of response, awake versus anesthesia, anesthesia versus first reaction, and anesthesia versus extubation was analyzed with the prediction probability.

RESULTS

SE correlates best with sedation levels, but no significant differences of the prediction probability values among SE, RE, and BIS were found. The prediction probability for all investigated steps of anesthesia did not show significant differences among SE, RE, and BIS. SE, RE, and BIS were superior to mean arterial blood pressure and heart rate.

CONCLUSION

SE, RE, and BIS revealed similar information about the level of sedation and allowed the authors to distinguish between different steps of anesthesia. Both monitors provided useful additional information for the anesthesiologist.

Effect of Different Cost Drivers on Cost per Anesthesia Minute in Different Anesthesia Subspecialties

Background

Little is known about differences in costs to provide anesthesia care for different surgical subspecialties and which factors influence the subspecialty-specific costs.

Methods

In this retrospective study, the authors determined main cost components (preoperative visit, intraoperative personnel costs, material and pharmaceutical costs, and others) for 10,843 consecutive anesthesia cases from a 6-month period in the 10 largest anesthesia subspecialties in their university hospital: ophthalmology; general surgery; obstetrics and gynecology; ear, nose, and throat surgery; oral and facial surgery; neurosurgery; orthopedics; cardiovascular surgery; traumatology; and urology. Using regression analysis, the effect of five presumed cost drivers (anesthesia duration, emergency status, American Society of Anesthesiologists physical status of III or higher, patient age younger 6 yr, and placement of invasive monitoring) on subspecialty-specific costs per anesthesia minute were analyzed.

Results

Both personnel costs for anesthesiologists and total costs calculated per anesthesia minute were inversely correlated with the duration of anesthesia (adjusted R2 = 0.75 and 0.69, respectively), i.e., they were higher for subspecialties with short cases and lower for subspecialties with longer cases. The multiple regression model showed that differences in anesthesia duration alone accounted for the majority of the cost differences, whereas the other presumed cost drivers added only little to explain subspecialty-specific cost differences.

Conclusions

Different anesthesia subspecialties show significant and financially important differences regarding their specific costs. Personnel costs and total costs are highest for subspecialties with the shortest cases. Other analyzed cost drivers had little effect on subspecialty-specific costs. In the light of these cost differences, a detailed cost analysis seems necessary before the profitability of an anesthesia subspecialty can be assessed.