Showing papers in "Acta Anaesthesiologica Scandinavica in 2001"

The assessment of postoperative cognitive function.

Abstract: Postoperative cognitive function (POCD) has been subject to extensive research. In the literature, large differences are apparent in methodology such as the test batteries, the interval between sessions, the endpoints to be analysed, statistical methods, and how neuropsychological deficits are defined. Traditionally, intelligence tests or tests developed for clinical neuropsychology have been used. The tests for detecting POCD should be based on well-described sensitivity and suitability in relation to surgical patients. In tests using scores, floor/ceiling effects may compromise the evaluation if the tests are either too easy or to difficult. Uncontrolled testing facilities and change of test personnel may affect the test performance. Practice effects are pronounced in neuropsychological tests but have generally been ignored. The use of a suitable normative population is essential to allow correction for practice effects and variability between sessions. Missing follow-up may severely compromise valid conclusions since subjects unable or unwilling to be examined are particularly prone to suffer from POCD. In the statistical analysis of the test results, the evaluation should be based on differences between pre- and postoperative performance. Parametric statistical tests are not relevant unless the appropriate Gaussian distributions are present, perhaps after transformation of data. The definition of cognitive dysfunction should be restrictive and the criteria should be fulfilled in only a small proportion of volunteers. In the literature, these requirements often have not been fulfilled. This precludes a reasonable estimation of the incidence of POCD and the conclusions of comparative studies should be interpreted with great caution. In this review article, we present a number of recommendations for the design and execution of studies within this area. In addition, the critical reader may use these recommendations in the evaluation of the literature.

Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain A quantitative systematic review

Abstract: Background: The usefulness of intravenous patient-controlled analgesia (PCA) with opioids for postoperative analgesia is not well defined. Methods: We systematically searched (MEDLINE, EMBASE, Cochrane Library, bibliographies, any language, to January 2000) for randomised trials comparing opioid-based PCA with the same opioid given intramuscularly, intravenously, or subcutaneously. Weighted mean differences (WMD) for continuous data, relative risks (RR) and numbers-needed-to-treat (NNT) for dichotomous data were calculated with 95% confidence intervals (CI) using fixed and random effects models. Results: Data from 32 trials were analysed: 22 (1139 patients) were with morphine, five (682) with pethidine, three (184) with piritramide, one (47) with nalbuphine and one (20) with tramadol. In three morphine and one pethidine trial (352 patients), more patients preferred PCA (89.7% vs 65.8%, RR 1.41 (95%CI 1.11 to 1.80), NNT 4.2). Combined dichotomous data on pain intensity and relief, and the need for rescue analgesics from eight morphine, one pethidine, one piritramide, and one nalbuphine trial (691 patients), were in favour of PCA (RR 1.22 (1.00 to 1.50), NNT 8). In two morphine trials (152), pulmonary complications were more frequently prevented with PCA (100% vs 93.3%, RR 1.07 (1.01 to 1.14), NNT 15). There was equivalence for cumulative opioid consumption, pain scores, duration of hospital stay, and opioid-related adverse effects. Conclusion: These trials provide some evidence that in the postoperative pain setting, PCA with opioids, compared with conventional opioid treatment, improve analgesia and decrease the risk of pulmonary complications, and that patients prefer them.

Risk factors for preoperative anxiety in adults.

Abstract: Background: Patients who undergo surgery experience acute psychological distress in the preoperative period. The objective of this study was to identify and quantify the effect of risk factors for preoperative anxiety in adults. Methods: A cross-sectional study was performed with 592 inpatients scheduled for elective surgery. Age ranged from 18 to 60 years (ASA physical status I–III). Demographic information was collected using a structured questionnaire. The measuring instruments were a visual analog scale, the State-Trait Anxiety Inventory, the Montgomery-Asberg Depression Rating Scale, the WHO Self-Reporting Questionnaire-20, and the future self-perception questionnaire. Multivariate conditional regression modeling was used to control confounding factors and to determine independent predictors of preoperative anxiety, taking into account the hierarchical relationship between risk factors. Results: High preoperative anxiety was associated with history of cancer (odds ratio (OR)=2.26) and smoking (OR=7.47), psychiatric disorders (OR=5.93), negative future perception (OR=2.30), moderate to intense depressive symptoms (3.22), high trait-anxiety (3.83), moderate to intense pain (2.12), medium surgery (OR=1.52), female gender (OR=2.0), ASA category III (OR=3.41), up to 12 years of education (OR=1.36), and more than 12 years of education (OR=1.68). Previous surgery (OR=0.61) was associated with lower risk for preoperative state-anxiety. Conclusions: History of cancer and smoking, psychiatric disorders, negative future perception, moderate to intense depressive symptoms, high trait-anxiety, moderate to intense pain, medium surgery, female gender, ASA category III, up to 12 years of education and more than 12 years of education constituted independent risk factors for preoperative state-anxiety. Previous surgery reduced the risk for preoperative anxiety.

A rational approach to the control of postoperative nausea and vomiting: evidence from systematic reviews. Part I. Efficacy and harm of antiemetic interventions, and methodological issues

Abstract: Postoperative nausea and vomiting (PONV) are among the most common adverse events related to surgery and anaesthesia. The truly medical impact of PONV is minor. It never becomes chronic, and it almost never kills, although prolonged vomiting may lead to more serious complications in rare cases (1, 2). In day-case surgery, PONV may delay discharge, and intractable PONV may lead to unplanned overnight admission. Thus, PONV may have an economic impact. From the patient’s perspective, PONV is undoubtedly distressing; it interferes with patients’ comfort. Surgical patients reported the fear of suffering PONV more often than the fear of postoperative pain (3). Several animal models have been established to investigate mechanisms and treatment of chemotherapy or radiation-induced sickness (4). There is no animal model of human PONV. Data on efficacy and harm of therapeutic or prophylactic PONV interventions, on risk factors, and on the underlying risk of PONV must, therefore, come from clinical reports. There are hundreds of published randomised controlled trials investigating the efficacy of interventions which are thought to have an impact on the incidence of PONV; well over 100 different antiemetic interventions have shown statistically significant antiemetic efficacy compared with a placebo in the surgical setting. For the last 40 years, numerous comprehensive reviews have tried to synthesise this heterogeneous information, and to provide recommendations on the best strat-

Chronic post-sternotomy pain.

Abstract: Background: Chronic postoperative pain is a well-recognised problem. The incidence of severe incapacitating pain is about 3–5% after various types of surgery such as thoracotomy, repair of inguinal hernias and mastectomy. Sternotomy causes considerable postoperative pain and patients with chronic post-sternotomy pain are often referred to pain clinics. Epidemiological studies on chronic post-sternotomy pain are scarce, however. The aim of this paper was to study the incidence and possible risk factors of chronic pain following sternotomy operations performed for coronary bypass grafting or thymectomy. Methods: Two groups of patients were studied for persistent pain following sternotomy operations. A questionnaire was sent in January 1997 to 71 patients with myasthenia gravis (MG) who had undergone a thymectomy during 1985–1996 and 720 patients who had had coronary bypass grafting (CABG) in 1994 were interviewed by letter. The patients were asked about the presence of pain and other symptoms in the chest, shoulders, arms or legs that they thought were connected to surgery. They were also asked about the quality of the pain and its evolvement with time. The patients’ records were checked for details about surgery, anaesthesia and the state of the coronary disease. Results: The response rate was 87%. The interval between the interview and surgery varied from 6 months to 12 years in the MG group and it was 2–3 years in the CABG group. In the MG group, 27% of the patients reported chronic post-sternotomy pain, which was moderate to severe in 48% of the patients. In the CABG group, 28% of the patients still had post-sternotomy pain, which was moderate to severe in 38% of patients. Of the patients who had post-sternotomy pain, one-third reported sleep disturbances due to the pain. Conclusion: Chronic post-sternotomy pain is an important complication that may have a significant impact on the patient’s everyday life. Future studies will show whether minimising complications, improving postoperative care and starting early adequate pain management will reduce the incidence of this problem.

Ultrasound control for presumed difficult epidural puncture.

Abstract: Background: The efficacy of epidural anaesthesia depends on the accurate identification of the epidural space (ES). Abnormal anatomical conditions may make the procedure difficult or impossible. The aim of this study was to investigate whether pre-puncture ultrasound examination of the spinal anatomy might be beneficial in expected cases of difficult epidural anaesthesia. Methods: We used digital ultrasound equipment with a 5-MHz transducer to assess the anatomy of the ES and the posterior parts of the spinal column. We examined 72 parturients with abnormal anatomical conditions who were scheduled for epidural anaesthesia. The women were randomised into two equal groups. In all patients, the standard loss of resistance technique was used. In the ultrasound group, an ultrasound examination of the appropriate spinal region was conducted prior to epidural puncture. ES depth seen on the ultrasound images was compared to the ES depth measured by the needle. We compared the number of puncture attempts with the standard method (control group) to the number of attempts under ultrasound guidance. Results: Ultrasonography significantly improved operating conditions for epidural anaesthesia. The maximum VAS scores and patient acceptance were significantly better. Conclusions: With ultrasound measurement of the ES depth, the quality of epidural anaesthesia was enhanced.

The incidence of chronic post-sternotomy pain after cardiac surgery : a prospective study

Abstract: Background Post-sternotomy pain is sometimes a sequela of cardiac surgery. The incidence, characteristics and clinical course of post-sternotomy pain are not well known. The aim of our study was to determine the incidence of chronic post-sternotomy pain in patients undergoing sternotomy for cardiac surgery in general and according to the specific surgical procedure. Method In a prospective manner, a group of 349 consecutive patients were evaluated for chronic post-sternotomy pain one year after surgery. The patients were asked in a postal questionnaire to describe and score any persistent pain following the surgical procedure. The patients were classified into 3 sub-groups according to surgical procedure. The first group consisted of patients operated for coronary artery by-pass grafting (CABG) including internal thoracic artery grafting (ITAG). The second group included patients operated with CABG without ITAG and the third group of patients with valve replacement without CABG. Result A total of 318 patients (91%) answered the questionnaire of whom 90 (28%) reported chest discomfort different from what they experienced before surgery. The scoring on the visual analogue scale (VAS, 0-100 mm) showed that 41 patients (13%) reported maximum pain intensity > or =30 mm (moderate pain), and 14 of these patients (4%) scored > or =54 mm (severe pain). There was no statistically significant difference in pain incidence and pain intensity when comparing the patients subjected to different surgical procedures. Conclusions This prospective study shows that the overall incidence of non-cardiac pain after sternotomy for cardiac surgery is high (28%). Most patients experience a modest pain intensity but some (1%) report severe pain, never being lower than 54 mm on VAS. The study also indicates that the incidence of pain after sternotomy is not only associated with harvest of the ITA and additional aetiological factors must be sought.

A rational approach to the control of postoperative nausea and vomiting: evidence from systematic reviews. Part II. Recommendations for prevention and treatment, and research agenda

Abstract: The control of postoperative nausea and vomiting (PONV) remains a difficult task. The optimal strategy to prevent PONV or to treat established symptoms is far from being obvious. Systematic reviews suggest that prophylaxis does not work very well, that there is a finite risk of adverse drug reactions with most antiemetic interventions, and that treatment may be more cost-effective than prophylaxis (1). Also, some interventions do not seem to work at all, and others are qualitatively or quantitatively very poorly documented. The intention of this second part of a series of two papers on rational strategies to control PONV symptoms was twofold. First, to provide clinically applicable recommendations on optimal prevention and treatment of PONV, based on data which represent the highest level of evidence currently available on efficacy and harm of antiemetic interventions. For this purpose, data from systematic reviews of relevant and valid randomised controlled trials only were considered (1). This does not exclude the possibility that clinicians may modify or adapt these recommendations by using valid data from individual studies on antiemetics which have not yet been reviewed systematically, and by taking into account their personal clinical experience. The second aim was to define an agenda for future PONV research. Systematic reviews are powerful tools to identify what we do not know (i.e. lack of evidence), and what we know with such

Intracerebral microdialysis and bedside biochemical analysis in patients with fatal traumatic brain lesions.

Abstract: Background: Microdialysis with bedside biochemical analysis was used to monitor cerebral biochemical alterations that precede and accompany increase in intracranial pressure (ICP), resulting in a complete cessation of cerebral blood flow. Methods: Seven patients, who died due to an untreatable increase in ICP, were included. The patients originate from a large, consecutive series of severely head injured patients (n: 95) monitored with intracerebral microdialysis (perfusion rate 0.3 μl/min). One microdialysis catheter was inserted via a separate burr hole frontally to that used for the intraventricular catheter (”better” position) and one catheter was inserted into cerebral cortex surrounding an evacuated focal contusion or underlying an evacuated haematoma (”worse” position). Biochemical analyses of glucose, lactate, glycerol, urea, glutamate, and pyruvate were performed at the bedside. All samples were frozen for subsequent HPLC (high-performance liquid chromatography) analyses of amino acids and ions. Results: Decreases in glucose and pyruvate and increases in lactate, glycerol, glutamate, and lactate/pyruvate (la/py) ratio characterized cerebral ischaemia. The measured markers give information regarding substrate availability (glucose), redox state of the tissue (la/py ratio), degradation of glycerophospholipids in cell membranes (glycerol), and extracellular concentration of excitatory amino acids (glutamate). In the “worse” position biochemical deterioration occurred before the increase in ICP. In the “better” position biochemical deterioration was usually observed after the increase in ICP. Conclusion: Changes of cerebral energy metabolism that accompany cerebral ischaemia follow a certain pattern and may be detected at the bedside by intracerebral microdialysis before the secondary damage causes an increase in ICP.

The systemic inflammatory response after cardiac surgery with cardiopulmonary bypass in children

Abstract: Paediatric cardiac surgery often requires cardiopulmonary bypass (CPB) during the surgical intervention CPB is known to elicit a systemic inflammatory response with activation of the complement and coagulation systems, stimulation of cytokine production, cellular entrapment in organs, neutrophil activation with degranulation, platelet activation, and endothelial dysfunction These changes are associated with a risk of postoperative organ dysfunction and increased morbidity and mortality in the postoperative period Clinical studies have concentrated on measurement of inflammatory markers and mediators in peripheral blood, where the systemic inflammatory response in the paediatric cardiac patient seems to be different from the adult case Looking at the organ level, experimental studies have the advantage of providing information contributing to a better understanding of the pathological events that may lead to the deteriorated organ function This review focuses on the systemic inflammatory response after cardiac surgery with CPB in children and experimental CPB models

Improved recovery after music and therapeutic suggestions during general anaesthesia: a double-blind randomised controlled trial.

Abstract: Purpose: This study was designed to determine whether music or music in combination with therapeutic suggestions in the intra-operative period under general anaesthesia could improve the recovery of hysterectomy patients. Methods: In a double-blind randomised clinical investigation, 90 patients who underwent hysterectomy under general anaesthesia were intra-operatively exposed to music, music in combination with therapeutic suggestion or operation room sounds. The anaesthesia was standardised. Postoperative analgesia was provided by a patient-controlled analgesia (PCA). The pain scores were recorded by means of a visual analogue scale. Nausea, emesis, bowel function, fatigue, well-being and duration of hospital stay were studied as outcome variables. Results: On the day of surgery, patients exposed to music in combination with therapeutic suggestions required less rescue analgesic compared with the controls. Patients in the music group experienced more effective analgesia the first day after surgery and could be mobilised earlier after the operation. At discharge from the hospital patients in the music and music combined with therapeutic suggestion group were less fatigued compared to the controls. No differences were noted in nausea, emesis, bowel function, well-being or length of hospital stay between the groups. Conclusion: This double-blind study has demonstrated that intra-operative music and music in combination with therapeutic suggestions may have some beneficial effects on postoperative recovery after hysterectomy. Further controlled studies are necessary to confirm our results.

Sevoflurane mask induction of anaesthesia is associated with epileptiform EEG in children.

Abstract: Background: Sevoflurane inhalation induction of anaesthesia is widely used in paediatric anaesthesia. We have found that this method is frequently associated with epileptiform electroencephalogram (EEG) in adults, especially if controlled hyperventilation is used. Methods: We assessed EEG during sevoflurane inhalation induction in 31 children, aged 2–12 yr. Anaesthesia was induced with 8% sevoflurane in O2 in N2O 1:2. The patients were randomized to undergo controlled ventilation (CV group), or to breathe spontaneously (SB group) for 5 min. EEG was recorded as were noninvasive blood pressure and heart rate (HR). EEG recordings were classified by a clinical neurophysiologist. Results: Three different types of interictal epileptiform discharge were detected. Suppression with spikes (SSP) was found in 25% and 0% in the CV and SB groups, rhythmic polyspikes (PSR) in 44% and 20%, and periodic epileptiform discharges (PED) in 44% and 0% (P<0.01), respectively. The incidence of all different types of interictal epileptiform discharge (SSP+PSR+PED) was 88% and 20% (P<0.001), respectively. Epileptiform EEG was associated with increased heart rate and blood pressure during anaesthetic induction. Conclusion: Both ventilation modes produced epileptiform EEG. With controlled ventilation, epileptiform discharges were seen in 88% of children. This warrants further studies of the suitability of this induction type in general, and especially in children with epilepsy.

Treatment with paracetamol in infants

Abstract: Background: Paracetamol (N-acetyl-p-amino-phenol) or acetaminophen has become the most widely used analgesic and antipyretic in children. However, there is a wide discrepancy between the extent to which paracetamol is used and the limited available pharmacological data in small infants. The purpose of this article is to present a review of the current literature regarding the use of paracetamol in neonates and infants with a particular emphasis on pharmacological issues. Methods: A MEDLINE search (up to March 2000) was conducted to identify relevant English-language publications using paracetamol, children, infants and neonates as search terms. Additional studies were identified from bibliographies of the reviewed literature. Results: Pharmacological studies on paracetamol in infants are few. Most studies have focused on the administration of one single paracetamol dose, and the problem of cumulative toxicity with repeated dosing has not been addressed. Plasma paracetamol concentration should be 10–20 mg ml−1 to achieve antipyretic and analgesic effects. The bioavailability of the different formulations and routes of administration vary with age. Rectal absorption is slower and more erratic than the oral; however, in the very young, rectal bioavailability is higher than in older patients. Volume of distribution seems to be age-independent, whereas clearance is reduced in neonates and particularly in preterm babies. Neonates and infants are capable of forming the reactive intermediate metabolite that causes hepatocellular damage, particularly after multiple doses. They have an immature glucuronide conjugation system, but the rate constant for the sulphation metabolic pathway is larger than in older children, and this is the most important route of metabolism. Conclusions: The pharmacokinetics and pharmacodynamics of paracetamol differ substantially in neonates and infants from those in older children and adults; hence, dosing should be adjusted accordingly.

Anaphylactic reactions in anaesthetised patients – four cases of chlorhexidine allergy

Abstract: Chlorhexidine is widely used all over the world in many different preparations. In Denmark chlorhexidine is the standard skin disinfectant used before surgery or invasive procedures and it is widely used in the general population in mouthwash or for disinfection of minor scratches etc. The potential for developing allergy to chlorhexidine is thus great, especially in surgical patients. We have identified four patients with serious allergic reactions in connection with surgery and general anaesthesia, who on subsequent skin testing tested positive for chlorhexidine. Symptoms appeared 20-40 min into the operation and all four patients required treatment with adrenaline. All four patients had a history of minor symptoms like rashes or faints in connection with previous surgery/invasive procedures. Allergy to chlorhexidine may be more prevalent in surgical patients and cases may have been overlooked due to the nature of reactions and lack of suspicion towards this substance.

Risk factors for nosocomial intensive care infection: a long‐term prospective analysis

Abstract: Background: To identify risk factors for nosocomial infection in intensive care and to provide a basis for allocation of resources. Methods: Long-term prospective incidence study of risk factors for nosocomial infection in the surgical-medical intensive care unit of a university hospital. Results: A total of 2671 patients were admitted during four years, and 562 of 574 patients staying >48 h were observed during 4921 patient days (median length of stay 5 days, range 2–114). Of these, 196 (34%) patients had 364 nosocomial infections after median 8–10 days, an infection rate of 14/100 admissions. Infection prolonged length of stay 8–9 days and doubled the risk of death. The infections were 17% blood stream, 26% pneumonias, 34% wound, 10% urinary tract and 13% other infections. The incidence of bloodstream infection declined significantly during the study years, from 12% to 5%. In multiple regression analysis, the important variables for infection were central venous catheter, mechanical ventilation, pleural drainage and trauma with open fractures. High age, immunosuppression and infection on admission did not influence the risk of acquiring infection. Trauma patients constituted 24% of the study population. Trauma with open fractures increased the risk of infection more than twice (P=0.003), mainly due to wound infections. Conclusion: Trauma cases, with open fractures, were the patients most at risk of infection, despite low disease severity scores. Resources to prevent nosocomial infection should be allocated to these patients.

Measuring patient satisfaction with anaesthesia: perioperative questionnaire versus standardised face-to-face interview.

Abstract: BACKGROUND Patient satisfaction represents an essential part of quality management. Measuring the degree of patient satisfaction can be achieved with a variety of tools such as postoperative visits and patient questionnaires. The primary aim of this study was to quantify the degree of patient satisfaction with anaesthesia. A secondary aim was to compare the questionnaire technique with standardised face-to-face interviewing. METHODS The authors prospectively studied 700 patients on the second postoperative day. Patients were randomised and allocated to complete either a written questionnaire or to answer the same questions during a standardised face-to-face interview. The questionnaire was subdivided into a set of questions on anaesthesia-related discomfort and another set on satisfaction with anaesthesia care in general. The questions on discomfort were assessed on a 3-point scale, and those on patient satisfaction on a 4-point scale. RESULTS Response rate was 84% (589 of 700 patients). Internal consistency, as measured by Cronbach's alpha, was 0.84. When evaluating the questions on anaesthesia-related discomfort, the most frequent sensations were "drowsiness" (>75%), "pain at the surgical site" (>55%), and "thirst" (>50%). The data on patient satisfaction showed a high degree of satisfaction (>90%). The responses to questions on anaesthesia-related discomfort revealed only minor differences between the questionnaire and the face-to-face interview. The questions on satisfaction with anaesthesia, however, were answered consistently in a more critical manner during the interview (P<0.0001). CONCLUSIONS The standardised interview may be more suited to determine patient satisfaction than a questionnaire. Quality improvements are possible for emergence from anaesthesia, postoperative pain therapy, and the treatment of postoperative nausea and vomiting.

An outcome study of severe traumatic head injury using the “Lund therapy” with low-dose prostacyclin

Abstract: BACKGROUND: There are two independent head injury outcome studies using the "Lund concept", and both showed a mortality rate of about 10%, and a favourable outcome (Glasgow outcome scale, GOS 4 and ...

Assessment of the efficacy of esmolol on the haemodynamic changes induced by laryngoscopy and tracheal intubation: A meta‐analysis

Abstract: Background Adrenergic stress response induced by laryngoscopy and tracheal intubation (LTI) appears to be attenuated by esmolol, but its potential clinical benefits have not been fully weighed against possible adverse effects Methods A systematic search up to May 2000 was performed using MEDLINE, EMBASE, LILACS, Cochrane library, manual searching and bibliographies in all languages All randomised comparisons of esmolol with placebo on the haemodynamic changes elicited by LTI were obtained Trials were included in the present meta-analysis if they recorded heart rate (HR), systolic pressure (SBP), mean arterial pressure (MAP) or diastolic pressure (DBP) at three different stages: pre-induction, immediately prior to intubation, and in the post-intubation period Weighted mean differences (WMD) and 95% confidence intervals (CI) of the changes in the haemodynamic variables between treatment and placebo groups were calculated Results Of 72 publications identified, 38 randomised controlled trials containing a total of 2009 patients were finally included Eleven different regimens and doses of esmolol demonstrated effectiveness in the attenuation of HR and BP after LTI in a dose-dependent manner The most effective regimen was a loading dose of 500 microg x kg(-1) x min(-1) over 4 min followed by continuous infusion dose of 200-300 microg x kg(-1) x min(-1) [WMD: 202 bpm (95% CI: 156 to 247)] High bolus dose (200 mg) of esmolol produced a considerable decrease in DBP [WMD 101 mmHg (95% CI: 73 to 128)] Conclusion Esmolol is effective, in a dose-dependent manner, in the attenuation of the adrenergic response to LTI To minimise its adverse effects it should be administered, when considered clinically appropriate, as a continuous infusion regimen

Danish Anaesthesia Allergy Centre – preliminary results

Abstract: Background: Anaphylactoid reactions in anaesthesia are rare and should ideally be investigated in specialist centres. At Gentofte University Hospital, we established such a centre in 1998 as a joint venture between the Departments of Anaesthesiology and Dermatology. We present the methodology, diagnostic algorithm and preliminary results from our centre. Methods: We are open for referral of patients from all of Denmark. Reactions are classified using a three-grade severity scale and all reactions ranging from mild to severe are investigated. Investigations follow a standard step-by-step protocol of in vitro testing and skin testing. Blood samples for tryptase analysis are taken at the time of reaction and a control sample is taken together with samples for specific IgE analysis 2-4 weeks after the reaction. Subsequent skin testing comprises both prick tests and intradermal tests in most cases. Patients are tested with all substances they were exposed to, including antibiotics, colloids, latex and chlorhexidine. Results: A total of 68 patients have been referred to date (July 2001) and 36 have completed investigations. Positive test results were mainly seen in patients with more severe reactions, and there were more men than women in the group with the most severe reactions. Six patients had positive specific IgE, three for penicillin, two for latex and one for thiopental. In all, 21 patients had positive skin tests to various substances, of whom four men with anaphylactic shock tested positive for chlorhexidine. Only one patient has tested positive to a neuromuscular blocking drug (NMBD) so far. Discussion: Our preliminary results appear to differ in two ways from results usually found in this field. Firstly, only one patient has tested positive for a NMBD and secondly, we have had four patients with anaphylactic shock who have tested positive for chlorhexidine. Possible reasons for these differences are discussed.

Symptom recognition in advanced cancer. A comparison of nursing records against patient self-rating.

Abstract: The aim of the study was to investigate the extent to which the symptoms experienced by advanced cancer patients were covered by the nursing records. On the day of the first contact with our palliative care department, a nursing record was taken, and on this or the following day, 56 patients filled in the questionnaires EORTC Quality of Life Questionnaire (EORTC QLQ-C30), Edmonton Symptom Assessment System (ESAS), and Hospital Anxiety and Depression Scale (HADS). In each patient, the symptomatology reported in the patient-completed questionnaires was compared with the symptomatology mentioned by the nurse in the nursing record. The analysis revealed good concordance concerning pain and poor physical functioning, but patients reported other symptoms or problems much more often than their nurses. Reasons for these discrepancies are discussed. It is suggested that the nurse's knowledge of the patient's symptomatology might gain from more systematic screening or from transfer of information from patient self-assessment questionnaires to the nursing records.

Pharmacokinetics and drug dosing adjustments during continuous venovenous hemofiltration or hemodiafiltration in critically ill patients.

Abstract: Continuous renal replacement therapy (CRRT) in critically ill patients with renal failure may significantly increase drug clearance, requiring drug dosing adjustments. Drugs significantly eliminated by the kidney often undergo substantial removal during CRRT, and a supplemental dose corresponding to the amount of drug removed by CRRT should be administered. Clearance by CRRT can either be measured or estimated. The high-flux membranes used in CRRT make no filtration barrier to most drugs, and the filtrate concentration can be estimated by the unbound fraction of the drug in plasma. When adding dialysis to filtration, this approach overestimates drug clearance, and a correcting factor should be used. A method for estimating drug clearance as a function of creatinine clearance is also suggested, but it has the same limitations in overestimating drug clearance when dialysis is combined with filtration. For non-toxic drugs, doses can safely be increased 30% above actual estimates to ensure adequate dosing. For drugs with a narrow therapeutical margin, monitoring plasma concentrations are mandatory. When appropriate, the use of a readily available reference for drug dosing is recommended.

A survey of tracheal intubation difficulty in the operating room: a prospective observational study.

Abstract: Background: The purpose of this study is to describe all degrees of endotracheal intubation difficulty among patients attended by eight anesthesiologists during routine surgery over a six-month period. Airway characteristics were routinely assessed preoperatively, according to the anesthesiologists’ usual practice. Methods: Difficult tracheal intubation was evaluated by the Intubation Difficulty Scale (IDS), a quantitative score based on seven variables. An IDS value of 0 is consistent with a procedure without difficulty, and an IDS > 5 with a procedure involving moderate to major difficulty. Results: For 1171 patients undergoing tracheal intubation, IDS was 0 in 55%, and greater than 5 in 8% of cases. External laryngeal pressure, repositioning the patient and added use of a stylet were the most frequent methods chosen to facilitate tracheal intubation. Conclusion: There was a high incidence (37%) of minor difficulties encountered during routine surgery.

Lack of agreement between thermodilution and carbon dioxide-rebreathing cardiac output.

Abstract: Background: A continuous, accurate, non-invasive monitor of cardiac output would represent a major step forward in patient management A cardiac output computer, NICO2, based on the Fick principle and an automatic partial carbon dioxide (CO2)-rebreathing technique has just become available We compared the performance of this monitor with the standard thermodilution method Methods: Thirty patients were investigated after cardiac surgery Replicate measurements were performed simultaneously with the thermodilution and NICO2 techniques An Altman-Bland analysis was used to assess repeatability of each of the two methods and to determine the agreement between the two techniques Results: The repeatabilities of thermodilution and CO2-rebreathing cardiac output were excellent, with coefficients of repeatability of 035 l/min and 060 l/min Mean thermodilution and NICO2 cardiac output were 44 l/min (SD 09, range 27–61) and 46 l/min (SD 13, range 16–69) A comparison of the methods, however, revealed excessive limits of agreement (±180 l/min) Conclusion: The agreement between the NICO2 derived cardiac output and the de facto standard – thermodilution cardiac output – is poor The methods are not interchangeable with the present version of the NICO2 The repeatability of the partial CO2-rebreathing technique holds promise that a sufficient accuracy may be obtained by suitable modifications of the monitor’s algorithms

Postoperative tracheal extubation after orthotopic liver transplantation.

Abstract: Background: The duration of postoperative mechanical ventilation and its influence on pulmonary function in liver transplant recipients is still debated controversially. Methods: We retrospectively analyzed the incidence of immediate tracheal extubation, prolonged mechanical ventilation (>24 h following surgery), and episodes of reintubation in 546 patients who underwent orthotopic liver transplantation (OLT) at our institution. Results: Immediate tracheal extubation in the operating theater was achieved in 18.7% of patients, and prolonged mechanical ventilation was required by 11.2% of patients. In these, median time of extubation was 49.5 h, whereas the remaining 70.1% of patients required ventilation support for a median 5 h after OLT. As risk factors for prolonged mechanical ventilation we identified the indications of acute liver failure and retransplantation, as well as factors such as mechanical ventilation prior to OLT, massive intraoperative bleeding, and severe reperfusion injury of the liver graft. The incidence of reintubation was 8.8% in patients who were immediately extubated following surgery, and 13.1% in patients who underwent extubation within 24 h. The incidence was significantly increased in patients requiring prolonged mechanical ventilation (36.1%). Conclusions: Immediate tracheal extubation was safe and well tolerated. The incidence of reintubation was not increased when compared to patients in whom extubation succeeded later. However, special attention should be given to transplant recipients presenting in reduced clinical condition at the time of OLT, undergoing complicated surgery, or receiving liver allografts with severe reperfusion injury because of an increased risk for prolonged mechanical ventilation.

An increased body mass index is no risk factor for postoperative nausea and vomiting. A systematic review and results of original data.

Abstract: Background: An increased Body Mass Index (BMI) is almost always mentioned as a fundamental risk factor for postoperative nausea (PN), vomiting (PV) or both (PONV). However, multivariate analyses were unable to detect any correlation. Therefore, we asked whether an increased BMI is really a risk factor for PONV. Methods: For the systematic review, a search of electronic databases and a detailed manual search of reviews were carried out. For the analysis of the original data, 587 adult patients from a randomised controlled antiemetic trial (RCT) who underwent general anaesthesia were allocated to four weight groups: Underweight (BMI<20), Normal Weight (BMI 20-25), Overweight (BMI 25-30) and Obesity (BMI≥30). Results: Four publications with original data were found. Two described a positive relationship, although not clearly supported by the data. Despite this, most narrative reviews claimed a positive correlation between obesity and PONV by quoting again narrative reviews or misquoting originals. In the RCT, the calculated underlying risk profile for PONV was comparable between all groups. Incidences (95% confidence intervals) of PONV were 45.8% (34.0; 57.6), 41.7 (36.5; 46.9), 47.8 (38.4; 57.1) and 44.1 (31.0; 57.1), for the groups Underweight, Normal Weight, Overweight and Obesity, respectively (P=0.69). The incidences of PN and PV also did not differ with P=0.76 and P= 0.36, respectively. Conclusion: Systematic search of the literature provides no evidence for a positive relationship. Furthermore, our data confirm that an increased BMI is not a risk factor for PONV. This negative finding is important as focussing on the relevant risk factors is needed to allow for an objective risk assessment of PONV.

Neuropathic pain: what do we do with all these theories?

Abstract: Only a generation ago there were few ideas as to what might cause neuropathic pain, and even fewer relevant data. In contrast, we can currently point to hundreds of distinct cellular changes that are triggered by nerve injury and that might be relevant to the emergence of pain symptomatology. The number may soon increase to thousands. It is essential, therefore, to redirect efforts towards the development of experimental strategies for testing which of these are essential parts of the pain process and which are tangential. In this paper I point out four such strategies: timing, deletion, prevention and genetic heterogeneity, and summarize how one neuropathic pain theory, the ectopic pacemaker hypothesis, holds up to scrutiny.

Clonidine decreases intraoperative bleeding in middle ear microsurgery.

Abstract: BACKGROUND The antihypertensive drug clonidine is a centrally acting alpha2 agonist useful as a premedicant because of its sedative, anxiolytic, and analgesic properties. We examined the effect of clonidine given as an oral preanesthetic medication in producing a bloodless surgical field in patients undergoing middle ear microsurgery. We also evaluated whether the administration of clonidine would alter the reflex cardiovascular response to laryngoscopy and endotracheal intubation, anesthetic requirement, postoperative pain intensity and consumption of analgesics, and pre- and postoperative sedation and anxiety. METHODS A prospective, randomized, double-blind clinical trial was performed in 40 patients scheduled for elective middle ear surgery under general anesthesia. Twenty-one patients received clonidine (300 microg p.o.) 90 min prior to arrival at the operating theater and 19 received placebo (control group). The hemodynamic endpoint of the anesthetic management was maintenance of hypotension for producing a bloodless surgical field. The desired control of the cardiovascular system was attained with isoflurane (inspired concentration increments of 0.25 vol% up to a maximum of 1.5 vol%)+/-fentanyl (bolus of 1 microg. kg-1)+/-urapidil (bolus of 0.3 mg. kg-1) as needed. Intraoperative bleeding was assessed on a four-point scale from 0=no bleeding to 3=abundant bleeding. RESULTS There was less bleeding in the clonidine group (mean+/-SEM) than in the control group (0.75+/-0.3 vs 1.1+/-0.4, P<0.05). Patients given clonidine required a mean inspired isoflurane concentration of 0.63+/-0.1 vol% as compared with 1.01+/-0.2 vol% in controls (P<0.05). Fentanyl requirements were also significantly lower (57.10 vs 79.42 microg. kg-1, P<0.05). Four clonidine-treated patients required urapidil to achieve satisfactory hypotension as compared with 11 controls (P<0.05). Clonidine attenuated the associated cardiovascular response following laryngoscopy and intubation, and was more effective than placebo in achieving a satisfactory preoperative sedation and decreasing intensity of postoperative pain. Preoperative anxiety and incidence of adverse events was similar in both groups. CONCLUSION Premedication with clonidine reduced bleeding in middle ear microsurgery, attenuated hyperdynamic response to tracheal intubation, and reduced isoflurane, fentanyl, and urapidil requirements for controlled hypotension.

Complaints related to respiratory events in anaesthesia and intensive care medicine from 1994 to 1998 in Denmark.

Abstract: Background: In Denmark, a National Board of Patients’ Complaints (NBPC) was founded in 1988. This study analyses anaesthetic complaints related to adverse respiratory events filed at the NBPC from 1994 to 1998 to point out directions for possible preventive measures. Methods: All decisions made by the NBPC from 1994 to 1998 concerning personnel employed in the Danish health care system were scrutinized. Cases related to anaesthesia and intensive care medicine were reviewed. Adverse respiratory events were identified and classified by mechanism of the incident that had caused the complaint. Detailed information on anaesthetic technique, personnel involved, sequence of events, clinical manifestation of injury, and outcome was recorded. Results: A total of 284 cases was identified. One-fifth (n=60) of the complaints were related to an adverse respiratory event. The overall mortality in these cases was 50% (n=30). In 19 complaints (32%), the treatment was considered substandard. Conclusion: Complaints related to respiratory events reveal that inadequate anaesthetic and intensive care medicine treatment leads to patient damage and death. Preventive strategies should be directed at the development of guidelines for handling the difficult airway, education in the management of the difficult airway, instruction in the correct use of anaesthetic equipment, improvement of interpersonnel communication routines, as well as implementation of simulator training.

Management of anaphylactic shock evaluated using a full‐scale anaesthesia simulator

Abstract: Background: The diagnosis of an anaphylactic reaction during anaesthesia is not the first consideration for the anaesthetist and might be missed. The aim of this study was to describe anaesthetists’ management of an anaphylactic reaction concerning diagnosing, treatment and application of anaesthesia crisis resource management (ACRM) in a full-scale anaesthesia simulator. Methods: Forty-two anaesthetists in teams of two attended training sessions with a critical incident of anaphylactic shock in a full-scale simulator. Trained observers from the study group evaluated the medical treatment according to a treatment sequence developed from the literature and graded the ACRM performance on a five-point scale where 1 is bad and 5 is best. Results: None of the teams made the correct diagnosis within 10 min and treatment according to the treatment sequence was not initiated. Only 6/21 teams considered the right diagnosis but first after hints from the instructor 15 min after the start of the incident. Evaluation of the use of the total ACRM concept (that is the use of all of the ACRM expressions seen in a total connection: called general impression) gave a median value of 2.0 with a range of (1–3). Conclusion: Anaphylactic shock was difficult to diagnose and no structured plans were used for the treatment in the simulated incident in this study.

Reduced isoflurane consumption with bispectral index monitoring.

Abstract: Background: Bispectral index (BIS) monitoring has been found to decrease the requirements for propofol, sevoflurane and desflurane and to improve recovery. We wanted to assess the effect of BIS monitoring on intraoperative isoflurane utilisation, and the early recovery profile. Methods: Eighty patients undergoing various surgical procedures were studied. In the first phase of the study, patients were anaesthetised without the use of BIS, the anaesthetists being blinded to the BIS readings, and isoflurane being administered according to standard clinical practice (control group). In a second phase, isoflurane was titrated to maintain a BIS value between 40 and 60 during surgery, and then 60–70 during 15 min prior to the end of surgery (BIS group). Isoflurane consumption was measured. Recovery times and the time to achieve a modified Aldrete score of 9 were recorded. Results: Despite similar mean BIS levels during maintenance of anaesthesia, the cumulative time spent with BIS values between 40 and 60 during maintenance of anaesthesia was significantly longer in the BIS group as compared with the control group (P<0.001). The isoflurane usage in the BIS group was 12–25% lower than in the control group (P<0.05). The time to awakening and extubation were comparable in the two groups. Although the patients were less sedated (P<0.01) during the three postoperative hours in the BIS (vs. control) group, no significant differences were observed in the time to obtain an Aldrete score of 9. Conclusion: The addition of BIS to standard monitoring decreases isoflurane consumption. However, we found only a small advantage in using BIS with respect to recovery from isoflurane anaesthesia.