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T Pedersen

Publications and source records attributed to T Pedersen.

At least 19 recordsLinked to original sources
PubMed2006

Identifying the European fossil fuel plumes in the atmosphere over the Northeast Atlantic Region through isotopic observations and numerical modelling.

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO(2) over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO(2) sampling stations, built at University of Copenhagen, for (14)C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO(2) due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO(2). During the project period (1998-2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO(2), as expected, is largest (up to 3.7+/-0.4% fossil CO(2)) at the Danish location closest to the European emissions areas and much weaker (up to approximately 1.5+/-0.6% fossil CO(2)) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background (14)CO(2) activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO(2) over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO(2).

Air Pollutants↗
PubMed2006

Scrutinizing incident reporting in anaesthesia: why is an incident perceived as critical?

BACKGROUND: The purpose of the present study was to measure the incidence and type of incidents that occurred in relation to anaesthesia and surgery during a 1-year period in six Danish hospitals. Furthermore, we wanted to identify risk factors for incidents, as well as risk factors for incidents being deemed critical. METHODS: A four-page questionnaire describing patient data, type of anaesthesia and surgery, and occurrence of incidents was filled in for all anaesthesias in the period, and subsequently processed. The incident reporting form incorporated 59 predefined adverse events. The occurrence of one or more of these events described the incident. When the reporting anaesthetist deemed that an incident had harmed the patient, that incident was defined as critical. RESULTS: A total of 64,312 anaesthesias were reported, and in 7754 of them one or more incidents occurred. A total of 8510 incidents occurred, 4077 of them were solely related to the anaesthetic procedure, 3702 described events related to physiological alterations in the patient (physiological incidents). Three hundred and twenty-three of the incidents were deemed critical. High ASA score, high age, abdominal surgery, urgent surgery, and complex anaesthetic procedure were significant risk factors for physiological incidents and critical incidents. We could not identify a simple subset of adverse events that could adequately be used to describe the critical incidents. However, complex incidents, i.e. incidents involving more than one adverse event, were more likely to be deemed critical than simple incidents. CONCLUSION: The incidence of incidents was 12.1%, and the incidence of critical incidents was 0.5%. Incidents were more likely to be deemed critical in patients with an ASA score of III and above undergoing urgent surgery.

Anesthesia Department, Hospital↗
PubMed2003

A study of the impact of long-term tobacco smoking on postoperative intensive care admission.

Smoking is a risk factor for intra-operative pulmonary complications and a wide range of postoperative pulmonary, cardiovascular, infection and wound-related complications. These may all lead to unplanned postoperative intensive care admission. We tested the hypothesis that smokers have an increased incidence of postoperative intensive care admission and more postoperative complications than nonsmokers in a general and orthopaedic surgical population. The following information was assessed in 6026 surgical patients: age, sex and smoking status (pack-years), history of heart and lung disease, American Society of Anesthesiologists (ASA) physical classification, intensive care admission and postoperative complications. Two thousand five hundred and twenty-six (46%) were smokers but for 620 patients (10.3%) smoking status was not confirmed. Postoperative intensive care admission was required by 319 patients (5.3%). Patients with > 50 pack-years were admitted to the intensive care more frequently than were smokers with < or = 50 pack-years history and nonsmokers (p < 0.001). Ex-smokers with > 50 pack-years history had the same risk of postoperative admission to intensive care as smokers with > 50 pack-years history. Smokers admitted to intensive care with > 50 pack-years history had a higher incidence of chronic lung disease (p < 0.005) and heavy alcohol consumption (p < 0.001). These smokers also had a higher incidence of postoperative pulmonary complications (odds ratio = 3.91, p < 0.01). The mortality rate was 37% in smokers with > 50 pack-years history and 24% in nonsmokers (odds ratio = 2.02, p = 0.08). We conclude long-term tobacco smoking (> 50 pack-years) carries a higher risk of postoperative admission to intensive care, and there seems to be a dose relationship between the amount of tobacco consumed and the risk of postoperative intensive care admission.

Adult↗
PubMed2002

Perioperative risk factors in elective pneumonectomy: the impact of excess fluid balance.

BACKGROUND AND OBJECTIVE: This study was performed to identify risk factors for complications and in-hospital mortality associated with pneumonectomy. METHODS: The influence of fluid balance during anaesthesia was evaluated, taking into account the patient's age, gender and body mass index, smoking habits, history of pulmonary or cardiac disorders, the site of pneumonectomy and duration of anaesthesia. One-hundred-and-seven patients undergoing elective pneumonectomy were included in the study. RESULTS: A total of 31 patients (29%) suffered from one or more postoperative complications, seven (22.4%) of these had severe dysrhythmias, six (19.6%) had pulmonary complications and three (9.3%) had cardiovascular complications. The overall mortality rate was 10.3%. CONCLUSIONS: Based on logistic regression analysis, our data indicate the following risk factors for postoperative complications: positive fluid balance exceeding 4000 mL during anaesthesia (pulmonary complications and mortality), body mass index < 17 or > 25 kg m(-2) (severe dysrhythmias), or history of chronic heart disease (pulmonary complications). Thirteen patients (12.4%) suffered from a fluid balance > 4000 mL during anaesthesia. Regression analysis indicated that fluid balance exceeding 4000 mL was associated with a higher risk of postoperative complications than blood loss exceeding 1000 mL and to be the strongest risk factor for postoperative pulmonary complications and in-hospital mortality. Further trials estimating the effect of restrictive fluid regimens and the use of vasopressors for blood pressure control during anaesthesia must be carried out.

Adult↗
PubMed2001

[What is evidence-based medicine?].

Evidence-based medicine is based on the best results from clinical and epidemiological research, which is combined with clinical experience and patient preferences. Questions of prognosis and harm are often best elucidated in large cohort studies. For other clinical questions the best evidence is usually found by systematic review of randomised trials, if possible in the form of meta-analyses. To make a diagnosis is, for example, not an aim in itself but a way to arrive at a prognosis and to suggest a treatment, provided this leads to a better prognosis. The most relevant, albeit rarely seen, test of a diagnostic method is a randomised trial. Evidence-based medicine will provide the best basis for evaluations of which interventions should be abandoned and which are effective and economically feasible. The use of evidence-based clinical guidelines will lead to more cost-effective treatments. It should be a national strategy that health care should be evidence-based.

Cost-Benefit Analysis↗
PubMed2001

[Premedication in ambulatory surgery].

UNLABELLED: A substantive amendment to this systematic review was last made on 3 January 2000. Cochrane reviews are regularly checked and updated if necessary. OBJECTIVES: To assess the effect of anxiolytic remedication on time to discharge in adult patients undergoing day case surgery under general anaesthesia. SEARCH STRATEGY: Trials were identified by computerised searches of the Cochrane Controlled Trials Register, MEDLINE, EMBASE, by checking the reference lists of trials and review articles, by handsearching three main anaesthesia journals and by contacting five researchers active in the field and the Product Information departments of the manufactures of five commonly used premedicants. SELECTION CRITERIA: All randomised controlled trials comparing an anxiolytic drug(s) with placebo before general anaesthesia in adult day case surgical patients. DATA COLLECTION & ANALYSIS: We collected data on anaesthetic drugs used, results of tests of psychomotor function where these were used to assess residual effect of premedication, and on times from end of anaesthesia to ability to walk unaided or readiness for discharge from hospital. Formal statistical synthesis of individual trials was not performed in view of the variety of drugs studied. MAIN RESULTS: Searching identified twenty-nine reports; fourteen studies, with data from a total of 1263 patients, were considered eligible for analysis. Only two studies specifically addressed the discharge question; both found no delay in premedicated patients. Three other studies used clinical criteria to assess fitness for discharge, though times were not given. Again, there was no difference from placebo. Four studies used both clinical measures and tests of psychomotor function as tests of recovery from anaesthesia. In none of these studies did the premedication appear to delay discharge, although performance on tests of psychomotor function was sometimes still impaired. Of the four studies which used tests of psychomotor function to assess recovery, three showed impaired recovery (after midazolam 7.5 mg, midazolam 15 mg or diazepam 15 mg) which might possibly interfere with discharge from hospital. REVIEWERS' CONCLUSIONS: We have found no evidence of a difference in time to discharge from hospital in patients who received anxiolytic premedication. However, in view of the age and variety of anaesthetic techniques used, inferences for current day-case practice should be made with caution.

Ambulatory Surgical Procedures↗
PubMed2001

Pulse oximetry for perioperative monitoring.

BACKGROUND: Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and consequently, correction of perioperative events that might cause postoperative complications or even death. Only a few randomised clinical trials of pulse oximetry have been performed during anaesthesia and in the recovery room which describe perioperative hypoxaemic events, postoperative cardiopulmonary complications and cognitive dysfunction. OBJECTIVES: To study the effect of perioperative monitoring with pulse oximetry to clearly identify the adverse outcomes that might be prevented or improved by the use of pulse oximetry. SEARCH STRATEGY: Trials were identified by computerised searches of the Cochrane Library, MEDLINE, EMBASE, and by checking the reference lists of trials and review articles. SELECTION CRITERIA: All controlled trials that randomised patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room. DATA COLLECTION AND ANALYSIS: We collected data in relation to events detectable by pulse oximetry, any serious complications that occurred during anaesthesia or in the postoperative period, intra- or postoperative mortality, and duration of recovery or intensive care stay. Formal statistical synthesis of individual trials was not performed in view of the variety of outcomes studied. MAIN RESULTS: Searching identified six reports; four studies with data from a total of 21,773 patients were considered eligible for analysis. Only two studies specifically addressed the outcomes in question; both found no effect on the rate of postoperative complications using perioperative pulse oximetry. Two studies used hypoxaemia detectable by pulse oximetry to assess the value of perioperative monitoring, although outcomes were not given. It was found that hypoxaemia was reduced in the pulse oximetry group both in the operating theatre and in the recovery room. During observation in the recovery room, the incidence of hypoxaemia in the pulse oximetry group was 1.5-3 times less. The postoperative cognitive function using the Wechsler memory scale and continuous reaction time was independent of perioperative monitoring with pulse oximetry. The other study showed that postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group. The two groups did not differ in cardiovascular, respiratory, neurologic, or infectious complications. The duration of hospital stay was a median of 5 days in both groups, and an equal number of in-hospital deaths was registered in the two groups. REVIEWER'S CONCLUSIONS: The studies confirmed that pulse oximetry can detect hypoxaemia and related events. However, we have found no evidence that pulse oximetry affects the outcome of anaesthesia. The conflicting subjective and objective results of the studies, despite an intense, methodical collection of data from a relatively large population, indicates that the value of perioperative monitoring with pulse oximetry is questionable in relation to improved reliable outcomes, effectiveness and efficiency.

Humans↗
PubMed2001

Interventions for preoperative smoking cessation.

BACKGROUND: Smokers have a substantially increased risk of intra and postoperative complications. Preoperative smoking intervention may be effective in decreasing this incidence. The preoperative period may be a well chosen time to offer smoking cessation interventions due to increased patient motivation. OBJECTIVES: The objective of this review was to assess the effect of preoperative smoking intervention on smoking cessation in the postoperative period and longer term. We also set out to determine the effect of smoking cessation on the incidence of postoperative complications. SEARCH STRATEGY: The specialised register of the Tobacco Addiction Group was searched using the free text and keywords (surgery) OR (operation) OR (anaesthesia) or (anesthesia). The databases "EMBASE" and "CINAHL" were also searched, combining tobacco and surgery related terms. SELECTION CRITERIA: We considered randomised trials which recruited smokers prior to surgery, offered a smoking cessation intervention, and measured abstinence from smoking in the pre-operative and post-operative periods. We also considered randomised trials of the effect of smoking cessation on the incidence of intra and post-operative complications. DATA COLLECTION AND ANALYSIS: The reviewers independently assessed studies to determine eligibility. The results were discussed between the reviewers. MAIN RESULTS: No trial meeting the inclusion criteria was found. REVIEWER'S CONCLUSIONS: We found no evidence to determine the effectiveness of pre-operative interventions in helping people to stop smoking, or of the effectiveness of smoking cessation in reducing peri-operative complications. However, observational evidence suggests benefits in stopping smoking before surgery. Although there is no direct evidence about which interventions work best in patients preparing for surgery, behavioural and pharmacological interventions shown to be effective in other settings should be considered.

Humans↗
PubMed2001

Demographic and medical predictors of medication compliance among ethnically different pediatric renal transplant patients.

Medication adherence in African-American and European-American pediatric renal transplant recipients was evaluated by four separate measures. Demographic and medical factors were analyzed. Based on pill count/refill history, European-American females were more compliant than their male counterparts. Based on self-ratings of compliance, African-American recipients were more compliant if they had vs. had not had dialysis experience prior to their transplant. These recipients also had higher self-ratings of compliance if their donors were cadaveric rather than living related.

Adolescent↗
PubMed2001

Postoperative intensive care admittance: the role of tobacco smoking.

BACKGROUND: Smokers have been shown to have increased risk of intraoperative pulmonary complications and of a wide range of postoperative complications, but an increased risk of postoperative intensive care admittance has not yet been described. The aim of this study was to estimate the risk of pulmonary complications and postoperative intensive care admittance in smokers and non-smokers in a general and orthopaedic surgical population. METHODS: A total of 4725 surgical patients were assessed. The following information was noted: age, sex and smoking status, history of heart and lung disease, ASA classification, type of anaesthesia, intensive care admittance and postoperative pulmonary or cardiovascular complications. A logistic regression model was used to determine the probability of intensive care admittance and pulmonary complications as a function of smoking status, age, and chronic heart and lung disease. RESULTS: Of the patients, 39.9% were smokers, 45.5% were non-smokers and in 14.6% of the cases smoking status was unspecified. Postoperative intensive care admittance and pulmonary complications were found in 2.0% and 4.3% of the patients, respectively. Non-smokers were more often female (P<0.01), and smokers had a higher incidence of emergency surgical procedures (P<0.05). When applying multiple regression analysis, we found that smoking, age >65 years, and a history of chronic lung disease increased the risk of unplanned intensive care admittance (odds ratio 1.55, 12.52 and 2.73). CONCLUSION: Our results indicate a relationship between a history of tobacco smoking and postoperative intensive care admittance.

Adolescent↗
PubMed2001

Risk factors for a major coronary event after myocardial infarction in the Scandinavian Simvastatin Survival Study (4S). Impact of predicted risk on the benefit of cholesterol-lowering treatment.

AIMS: To analyse (1) the prognostic importance of clinical findings and lipids in patients with a previous myocardial infarction and (2) the relative and absolute benefit of simvastatin in patients at low, medium and high predicted risk. METHODS: The 4S was a double-blind, randomized, clinical trial of long-term treatment with simvastatin or matching placebo in patients with myocardial infarction or angina pectoris, serum total cholesterol 5.5-8.0 mmol x l(-1), and serum triglycerides <or=2.5 mmol x l(-1). The present study only deals with those 3525 patients who had a previous myocardial infarction. End-points comprised coronary death, definite and probable hospital verified myocardial infarction, and resuscitated cardiac arrest. Because there were few women the primary analyses were performed among men. RESULTS: A Cox model analysis in the placebo group identified the following independent predictors of coronary events: a history of hypertension (P=0.023), diabetes (P=0.0001), smoking after the myocardial infarction (P=0.010), total cholesterol (P=0.020), and HDL cholesterol (P=0.062). The relative reduction of risk by simvastatin treatment in patients at low, medium and high predicted risk was 38%, 39% and 42%, respectively, but the corresponding absolute benefit per 100 patients treated for 6 years increased from 7.9 to 16.2. CONCLUSION: In addition to serum lipids, clinical variables contributed significantly to prediction. The relative benefit from simvastatin treatment was independent of predicted risk, but the absolute benefit increased from low to high risk.

Anticholesteremic Agents↗
PubMed2001

Self-regulation predictors of medication adherence among ethnically different pediatric patients with renal transplants.

OBJECTIVE: To predict medication adherence among ethnically different pediatric patients with renal transplants between the ages of 6 and 20 years old, using self-regulation variables including motivation, perceived control and responsibility, and perceived support. METHODS: Twenty-six African American children and 42 Caucasian children were verbally administered the Self-Regulation of Medication Adherence Battery to assess their (1) motivation to be medication adherent, (2) perceived control of and responsibility for medication adherence, and (3) perceived support of medication adherence from their primary caregiver. Four measures were used to assess medication adherence: self-ratings, nephrologists' ratings, cyclosporine levels, and pill count/refill histories. RESULTS: For the African American patients, regression analyses revealed that responses to motivation and perceived control questions that focused on self-efficacy were unique predictors of medication adherence as rated by their primary nephrologist. For the Caucasian patients, one motivation question regarding how often they forget to take their medication predicted their self-reported adherence. CONCLUSIONS: Facilitating their beliefs that they can regularly take their medications may help promote medication adherence among African American children with renal transplants, whereas for Caucasian children, providing cues and reminders to take their medications may help. We discuss implications of the results for multimodal assessment of medication adherence and for ethnic group-specific medication adherence research and interventions.

Adolescent↗
PubMed2001

Veno-venous bypass in liver transplantation: heparin-coated perfusion circuits reduce the activation of humoral defense systems in an in vitro model.

We studied the effects of bypass circuit surface heparinization on kallikrein-kinin, coagulation, fibrinolytic and complement activation in a closed model system for simulating veno-venous bypass (WBP) in orthotopic liver transplantation (OLT). The circuits were identical to those in routine use during clinical OLT in our institution. Fresh whole human blood diluted 1:2 with Ringer's acetate was circulated at a non-pulsatile flow (2 l/min) and at a constant temperature (37.5 degrees C) for 12 h. In 10 experiments, the entire inner surface of the circuits was coated with end-point attached heparin (HC). In the remaining 10, non-treated PVC tubing was used (NC). Components of the plasma kallikrein-kinin, coagulation, fibrinolytic and complement systems were analyzed using functional techniques (chromogenic peptide substrate assays) and enzyme immunoassays at baseline, 3 and 12 h. Significant activation of the initial (C3bc) and terminal (TCC) components of the complement system were found in both the NC and HC groups after 3 and 12 h: C3bc: NC: baseline = 4 (3.5-7.7), 3 h = 17.3* (12.5-27), 12h = 31* (17.7-63.6), HC: baseline = 4.9 (3.2-6.8), 3h = 9* (6-14.4), 12h = 13.7* (7.4-18.1). TCC: NC: baseline = 0.4 (0.2-0.6), 3h = 5*(0.8-11.9), 12 h: 13.1* (4.2-25.7). HC: baseline = 0.5 (0.1-0.6), 3 h = 0.6* (0.1-0.8), 12 h = 1.2* (0.3-2) AU/ml; median and range (*: p < 0.05). The C3bc and TCC concentrations were significantly higher in the NC group at 3 and 12 h, compared to the HC group: C3bc (NC vs. HC group): 3 h, p < 0.001; 12 h, p < 0.001. TCC (NC vs. HC group): 3h, p < 0.001; 12 h, p < 0.001. Significant increases in the values of thrombin-antithrombin complexes (p = 0.003), prothrombin fragment 1 + 2 (p = 0.006) and plasmin-alpha2-antiplasmin complexes (p = 0.016) were found in the non-coated group, but not in the heparin-coated group during the observation period, showing that the coagulation and fibrinolytic systems were activated in the non-coated circuits. We conclude that heparin-coating of the internal surface of the extracorporeal perfusion circuit used for WBP reduces activation of the plasma cascade systems in a closed venous system in vitro.

Blood Coagulation Factors↗