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Biomedical subjects

L E Larsen

Publications and source records attributed to L E Larsen.

At least 37 records · Page 2Linked to original sources
PubMed1994

Out-patient surgery--a survey of anaesthesia care in a university hospital.

This study was done at the Linköping University Hospital, Sweden, to assess the quality of care given to patients undergoing outpatient anaesthesia. A questionnaire was given to all adult patients (> 15 years old) immediately on admission to the outpatients' surgical ward and the patients were asked to answer all the questions, if necessary with the help of an attending nurse. Another questionnaire was given to the patients in the post-operative ward immediately prior to their being discharged home. Analyses of results indicate that although most patients were satisfied with the care offered at the outpatient surgical unit, 50% requested, but were not given, anxiolytic premedication before the operation. A majority of these were women undergoing gynaecological operations. Twenty per cent of the patients complained of post-operative pain that was poorly managed. Drowsiness (12%), headache (10%), and sore throat (8%) were common complications following general anaesthesia. In contrast, patients who had regional or local anaesthesia had an extremely low incidence of complications. Almost one-third of the patients were discharged without a responsible person accompanying them home and 25% were alone at home during the first 24 hours. Of the patients who went home alone, most either walked, cycled or took the bus, but 4% actually drove home after the operation. In our opinion more stress should be laid on patient information before the operation and better methods to relieve preoperative anxiety should be used whenever indicated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

The value of three-dimensional radiotherapy planning in advanced carcinoma of the urinary bladder based on computed tomography.

Since 1987, radiotherapy planning of advanced bladder cancer T3-T4 has been based on computed tomography (CT), and since 1989 we have used a three-dimensional (3-D) planning system. The treatment plans of 110 patients referred to our department in 1989-1991 have been evaluated. The field sizes used after CT-based treatment planning were compared with the field sizes that would have been used after conventional planning alone (cystogram). The changes of the treatment plans are described. In 62 (60%) cases the treatment plans were altered because of the CT-scans, mainly as an enlargement of the fields. The field enlargements were mostly in the dorsal and caudal direction. In 10 (10%) cases the CT-scans provided diagnostic information which contra-indicated the proposed radical irradiation. The 3-D dose planning system has been of great value, especially the beams-eye view presentation which is an efficient tool for adjusting the field size.

Carcinoma↗
PubMed1993

Randomized perturbed posturography: methodology and effects of midazolam sedation.

To study quiescent stance without applying external disturbances is not a theoretically appealing way to unveil the dynamic properties of human equilibrium. Methods to disturb equilibrium range from standing on foam surface, attaching vibrators to the calves to interfere with somatosensation, and exposure to body-position tracking environments, as in dynamic posturography (EquiTest). The EquiTest apparatus was modified by a menu-driven software to allow arbitrary movements of the support surface and visual surround, and force data were recorded for subsequent analysis. The support surface was randomly moved in the antero-posterior direction. First equilibrium was studied on the stable support surface, then low (RMS 1.3 cm) and high (RMS 2.6 cm) amplitude movements were used. Vision was either present or absent at all test amplitudes. Equilibrium was evaluated by the confidence (61%) ellipse sway area and average sway velocity during 45 s. Eleven healthy subjects aged 23-36 years (mean 29) were sedated with a short acting sedative, midazolam 0.1 mg/kg. Randomized perturbed posturography was conducted at baseline, and at about 60, 120 and 180 min after injection. Psychomotor tests were conducted at baseline, and at 30, 90, 150 and 210 min. Large interindividual variations were found. One subject could not be tested at all at 60 min due to sleepiness, whereas some subjects felt nearly full awake at 30 min. Sway areas were larger at 60 min, but not subsequently. At 60 min, sway velocities with open eyes were higher, just as when vision was absent and low amplitude movements were used. Later no effects could be shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Psychomotor recovery following propofol or isoflurane anaesthesia for day-care surgery.

A newly developed test for the assessment of psychomotor recovery--the perceptive accuracy test (PAT)--is described. Seventy-four subjects who performed the test though that it was easy to perform and some were motivated to try it on a number of occasions. Eight persons performed the test on different days and at different periods of time; the results were consistent and reproducible. Eight more persons were then asked to do the test 4 times at 15-min intervals; no 'learning' was seen with this test. A randomized, prospective study was then performed in two groups of 15 patients, undergoing arthroscopic procedures of the knee. Anaesthesia was induced with propofol and maintained with an infusion of propofol 12 mg/kg/h for the first 15 min, followed by 8 mg/kg/h subsequently in the propofol group. In the isoflurane group, anaesthesia was also induced with propofol, but isoflurane (0.5-2%) was used to maintain anaesthesia. Alfentanil was the analgesic used in both groups of patients. Results were compared with a third group of unanaesthetised controls, who were asked to perform psychomotor tests including choice reaction time and PAT at 30-min intervals for 2.5 h. There was a significant difference (P less than 0.01) in psychomotor recovery on the PAT-200 between the propofol group and control groups, but not in the isoflurane and control groups at 30 min. Both groups had returned to baseline values at 60 min in the PAT-60 and PAT-200. The choice reaction time showed no significant difference in either group 30 min after the anaesthetic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Thiopentone or propofol for induction of isoflurane-based anaesthesia for ambulatory surgery?

This study compares psychomotor recovery following induction of anaesthesia with either thiopentone or propofol in 30 healthy, unpremedicated patients undergoing outpatient arthroscopic procedures of the knee. A battery of tests including simple reaction time (SRT), choice reaction time (CRT), perceptive accuracy test (PAT) and digit symbol substitution test (DSST) were done before anaesthesia. The patients were randomly divided into two groups: Group 1 was induced with thiopentone 5-6 mg/kg while Group 2 was induced with propofol 2-3 mg/kg. Anaesthesia was then maintained with isoflurane (0.5-2%) in oxygen and air, and supplements of alfentanil were given for analgesia during spontaneous respiration with a face mask. Psychomotor recovery assessed every 30 min postoperatively for 120 min showed that patients in Group 1 had not returned to baseline values until 120 min after the operation on the PAT, while those in Group 2 had returned to baseline values at 60 min. No patient had any significant side effects. The SRT, CRT and DSST proved to be relatively insensitive in the detection of residual effects of anaesthesia and had a significant learning effect. This study suggests that induction of anaesthesia with propofol followed by maintenance with isoflurane in oxygen and air during spontaneous ventilation is associated with rapid psychomotor recovery and is a suitable method for ambulatory surgery. The PAT is sensitive and not associated with some of the problems found with other commonly used tests.

Adult↗
PubMed1991

Hypoxaemia during anaesthesia--an observer study.

We have investigated 296 inpatients in a single-blind observer study to determine the incidence, degree and duration of hypoxaemia during anaesthesia. The clinical recognition of hypoxaemia, period of time until recognition and risk factors were studied. Oxygen saturation (Spo2) was monitored continuously with a pulse oximeter (Ohmeda, model 3700). One or more episodes of mild hypoxaemia (Spo2 86-90%) were recorded in 53% of patients. Severe hypoxaemia with Spo2 values less than 81% were recorded in 20% of patients. The mild hypoxaemic episodes lasted up to 34.6 min (mean 2.3 min) and 70% were not detected by the anaesthetist. In the remaining 30% of episodes, the anaesthetist diagnosed the complication with a mean time delay of 70 s. After intervention a mean time delay of 57 s was recorded until Spo2 exceeded 90%. Utilizing a stepwise multiple logistic regression analysis, we found that risk factors associated with a greater incidence of hypoxaemia were patient age (P less than 0.005) and anaesthetic technique (P less than 0.00001). We conclude that hypoxaemic episodes in our operating rooms are common during anaesthesia and suggest preoxygenation in all patients in addition to administration of supplementary oxygen during arousal from anaesthesia and during transfer to the recovery room.

Adolescent↗
PubMed1991

Computerized dynamic posturography: a new method for the evaluation of postural stability following anaesthesia.

Dynamic posturography, a new method to study postural stability in humans, was performed in 11 healthy volunteers before administration of midazolam 0.1 mg/kg body weight i.v., and repeated subsequently at 45, 105 and 165 min. Results indicate that balance was affected significantly (P less than 0.008) up to 45 min after i.v. midazolam and did not return to control values until 105 min. The quantified version of the Romberg test performed with the eyes open or closed using the Equitest did not appear to be sensitive in detecting residual effects of midazolam on balance. We conclude that healthy, young persons should not be considered to have regained postural stability for up to 105 min after sedation with midazolam. Dynamic posturography appears to be a useful test in the objective assessment of balance disturbances.

Adult↗
PubMed1989

[Computer-assisted anesthesia in children].

Anaesthesia for children demands insight into the physiological and pharmacological differences between children and adults and knowledge of the differences in anaesthetic equipment and the principles of treatment. A computer programme which calculates diverse data in connection with anasthesia in children is demonstrated after which the advantages and disadvantages of employing aids of this type are briefly discussed.

Anesthesia↗
PubMed1989

[Smoke poisoning. Inhalation injuries from remaining at the scene of a fire].

In 1987, 87 persons died in Denmark as the result of fires. Fifteen of these occurred after arson. The commonest immediate cause of death in connection with fire is smoke inhalation. The pathophysiology of smoke inhalation is reviewed. The injurious effects on health may be subdivided into three different groups, viz thermal injuries to the respiratory passages, hypoxia and carbon monoxide poisoning and the toxic effects on the pulmonary parenchyma of various compounds (particles, gases and steam) which develop from the burning materials in the process of burning. After this, the symptomatology and treatment of smoke inhalation are reviewed. Treatment is primarily supportive and symptomatic. Finally, the various fire-extinguishing agents employed to extinguish fires at present are reviewed. Some of these have potentially injurious effects.

Humans↗
PubMed1989

[Acute poisoning with organic phosphates treated at an intensive care unit].

During the period 1.1.1976 to 31.12.1985, 23 patients were treated in an intensive care unit following acute poisoning with organic phosphates. Sixteen of the cases of poisoning were intentional and were part of attempted suicide. Eight were accidental. The severe cases of poisoning were all attempted suicides. Nineteen of the cases of poisoning occurred during the months from April to August during which these sprays are employed. The average age was 41 years ant the sex ratio men: women was 3:0. Respirator treatment was necessary in six patients. Sixteen patients were treated with a bolus injection of atropine and/or continuous infusion and six of these patients received antidote treatment with obidoxim, simultaneously. It is concluded that the majority of cases of poisoning are with suicidal intent and employ preparations which are freely obtainable and that only very few cases of poisoning occur in professional persons in connection with their employment. Treatment of cases of acute poisoning with organic phosphates is both specific and symptomatic. A therapeutic programme is established which aims primarily at ensuring free respiration, prevention of further absorption of poison, specific antidote therapy with atropine and obidoxim and symptomatic therapy.

Adult↗
PubMed1987

In vitro studies of microwave-induced cataract. II. Comparison of damage observed for continuous wave and pulsed microwaves.

Depth of damage caused by pulsed (PU) and continuous wave (CW) microwaves was estimated by scanning electron microscopy in rat lenses fixed immediately, after irradiation in vitro in circulating thermostatically controlled buffered saline. Pulses of 10 microseconds width and 24 kW peak power were delivered to the lens at different repetition rates in order to permit the same total energy to be delivered during 6, 20 or 60 min of irradiation at specific absorption rate (SAR) values of 0, 5.75, 11.5, 23, 69, 231 and 750 mW g-1; total energy [power (pow) x time] deposited in the lens was 0, 0.23, 0.46, 1.38, 4.6, and 15 W min g-1. Damage (granular degeneration of cells at the lens equator) was measured at the apex of penetration of the degeneration. The depth of degeneration (dep) of Pu or CW was compared either: (1) by a one-way analysis of variance (ANOVA) for the CW data alone and the 11 combinations of (pow x time); or (2) by using two alternative models to fit the data, to permit experimental distinguishment between: (a) reciprocal effects of pow x time; and (b) separate effects. Using the ANOVA analysis, the Pu mode of irradiation resulted in more damage at the same average power for every combination tested except one (23 mW g-1, 6 min). Although the separate-effects models explained more of the variation in depth of damage, the reciprocal effects model may provide an adequate fit for practical purposes and has the advantage of greater simplicity. For both models, the pulsed irradiation mode produced 4.7 times the depth of damage caused by CW irradiation. These results are discussed in relation to previous Pu-CW comparisons. It is proposed that this additional damage at the same average power is caused by thermoelastic expansion (TEE).

Animals↗
PubMed1985

In vitro studies of microwave-induced cataract: reciprocity between exposure duration and dose rate for pulsed microwaves.

Rat ocular lenses exposed to pulsed microwave irradiation were maintained at constant temperature by circulating phosphate buffered saline in a thermostatically-controlled chamber. Irradiations with pulsed radiation (10 musec, 24 kW pulses) of 918 MHz were done at several different specific absorption rates (SAR) for durations up to 1 hr in order to explore a possible reciprocal relationship. The extent of damage was measured by the maximum depth of granular degeneration in the equatorial region of lenses fixed immediately after irradiation. The parameters of the pulses were increased to 20 musec and 48 kW to explore the variation in the biological effects and threshold with respect to average power, as well as pulse parameters (pulse width, peak power and energy per pulse). A total of 47 lenses were used in 3 X 4 factorial experimental design to explore effects observed at different average powers and durations (6, 20 and 60 min). The results were statistically analyzed by ANOVA and multiple regression analysis with logarithmic transformation. The results are summarized as follows. This data showed clear trends towards increasing depth of granular degeneration with increasing duration of exposure and dose rate. There was considerable evidence to confirm such reciprocity suggesting that total dose is an important parameter. A model postulating reciprocity was shown to explain observed variation in depth of damage as well as one allowing for separate effects of duration and dose rate. Lens fibre cell effects were detected by scanning electron microscopy after 6 min irradiation at the SAR values of 40 and 20 mW g-1. Light microscopic evidence of lens fiber cell damage can be detected at an SAR of 10 mW g-1 after a 1 hr exposure.

Animals↗
PubMed1977

An off-line image processing system for digital display in computed tomography.

Early clinical application of an off-line image processing and analysis system for digital display in conjunction with computed tomography is described. The system consists of three operational subsystems: (a) a flexible disk for digital storage of absorption values in each of eight or more tomographic planes; (b) a high-speed interactive video system which displays the tomographic plane in correct geometry with the absorption values, which serve as the pictorial elements; and (c) a paper hard copy of the absorption values in a simulated gray-tone image of the tomographic plane in which the numerical values are the pictorial elements. Both the video and paper displays provide explicit numerical values of x-ray attenuation for each location on the tomographic plane in an image which combines analog and digital qualities.

Brain Neoplasms↗