PubMed HealthSearch

Biomedical subjects

B Löfström

Publications and source records attributed to B Löfström.

At least 19 recordsLinked to original sources

Risk evaluation and patient assessment in sedation.

Risk assessment gives a good clinical guide to the understanding of our patients' medical problems. The dentist can cope with problems related to patients belonging to risks group 1 and 2, but not to groups 3 or 4. The results of studies on risks, morbidity, and mortality in anaesthesia teach us that the human factor and technical error provoke complications, morbidity and mortality, seemingly unnecessarily. Case history and a simple physical examination, primarily concentrated on respiration and circulation, are of greatest importance. Main risks during conscious sedation are regurgitation and aspiration of fluid and smaller objects, such as a broken dentist's drill or a cardiac complication. Most feared is the risk of a reinfarcation. The aim of sedation is to reduce anxiety and restlessness. Of greatest importance is thorough patient information and a good doctor-patient contact.

Dental Care

Analysis of a system for ultrasonic imaging of attenuation and texture in soft tissue.

Attenuation in tissue decreases both the amplitude and the bandwidth of a reflected ultrasonic signal. Only the amplitude is restored in conventional ultrasonic equipment by amplifying the signal in a time-gain-compensator. This paper describes a method for restoring both the amplitude and bandwidth of the signal and an implemention of this method is proposed. This consists of two main parts: a device for estimating the attenuation and a time-variable circuit. The time-variable circuit is controlled by the estimated attenuation such that its transfer function approximates the inverse of the transfer function of the attenuation within the transducer passband. Its output is then almost independent of the attenuation and contains information on the texture of the tissue. Both the texture and attenuation estimates are displayed graphically. The quality of the image of the texture can be improved by choosing a wideband transducer, since it is almost exclusively dependent of transducer bandwidth.

Animals

Lidocaine and amitriptyline interaction during experimental haemoperfusion.

Displacement of amitriptyline by lidocaine was studied during haemoperfusion (HP) in five beagle dogs. Clearance of amitriptyline during HP was 0.93, although the amount of amitriptyline removed was only 2% of the given dose. Lidocaine does therefore not improve amitriptyline yield during HP. Clearance of lidocaine during HP was 0.99. Almost 13% of the lidocaine given intravenously was removed by HP. Lidocaine did not improve myocardial performance during HP in amitriptyline-intoxicated dogs. At necropsy the highest concentrations of amitriptyline in this model were found in the brain and the lung. The amitriptyline/nortriptyline ratio was lowest in the liver and lung, suggesting that these two organs are major sites of metabolism.

Amitriptyline

An oxygen-consuming model lung for evaluation of anaesthetic circuits.

We have constructed an oxygen-consuming model lung based on pure combustion of hydrogen. Besides consuming oxygen the model produces water vapour, and carbon dioxide is delivered to the lung, thus mimicking carbon dioxide production. Oxygen consumption and carbon dioxide production can be set at desired values. The model lung can be used for investigations on and evaluation of all types of anaesthesia circuits. Results in a circle system with carbon dioxide absorption show that FIO2 is related to the fresh gas flow. The end tidal CO2 level is correlated to the alveolar ventilation and cannot be used for predicting FIO2.

Anesthesiology

Thoracic gas volume and chest-abdomen dimensions during anesthesia and muscle paralysis.

The aim was to study thoracic gas volume (TGV) in anesthetized and paralyzed subjects (n = 16) and to analyze any change in TGV in terms of thoraco-abdominal dimensions. TGV was measured by means of a body plethysmograph, using a super syringe for lung inflation during muscle paralysis. The thoraco-abdominal shape at the mamillary and umbilical levels was studied by means of magnetometry for the assessment of antero-posterior diameters (A-P), a strain gauge technique for measuring circumferences and respiratory inductive plethysmography for the recording of cross-sectional areas. TGV was reduced by an average of 28 per cent, from 2.38 1 awake to 1.72 1 during pentothal anesthesia and spontaneous breathing. No change in A-P diameters or cross-sectional areas were noticed. Muscle paralysis and mechanical ventilation caused no further change in TGV, nor were there any changes in A-P diameters, circumferences or cross-sectional areas of the chest or abdomen. The rib cage contribution to the tidal breath was significantly increased, from 41 per cent to 62 per cent to the tidal volume. The result of a lowered TGV during anesthesia concurrently with no measurable change in chest-abdomen dimensions remains a paradox not yet fully understood.

Abdomen

Studies on pulmonary function in patients during respiratory treatment. Diagnostic and prognostic evaluations.

Twenty-nine patients, divided into three groups: 1) chronic obstructive pulmonary disease; 2) acute or chronic pulmonary disease with left heart failure; 3) respiratory insufficiency after peritonitis, pancreatitis, and/or sepsis, were studied during respirator treatment with regard to gas exchange, breathing mechanics and central circulation. The dead space ventilation was somewhat greater in group 1 than in the other groups. The alveolar-arterial oxygen tension difference was least in group 1, greater in group 2 and extremely high in group 3. Neither dynamic compliance of the thorax nor inspiratory resistance showed any significant differences between the groups. The cardiac output had the highest values in group 3. The venous admixture was generally small in group 1 and extremely large in group 3. The pulmonary artery pressures were highest in group 2. Three variables proved to be valuable when assessing the prognosis of a patient: a large venous admixture; a large alveolar-arterial oxygen tension difference, and a high pulmonary artery pressure indicated a less favourable prognosis.

Adult

Chest wall mechanics during artificial ventilation.

Chest wall mechanics were studied in six healthy volunteers before and during anesthesia prior to surgery. The intratracheal, esophageal, and intragastric pressures were measured concurrently. Gas flow was measured by pneumotachography and gas volume was obtained from it by electrical integration. Rib cage and abdomen movements were registered with magnetometers, these being calibrated by "isovolume" maneuvers. During spontaneous breathing in the conscious state, rib cage volume displacement corresponded to 40% of the tidal volume. During anesthesia and artificial ventilation, this rose to 72% of the tidal volume. The relative contributions of rib cage and abdomen displacements were not influenced by a change in tidal volume. Compliance was higher with a larger tidal volume, a finding which could be due to a curved pressure-volume relationship of the overall chest wall.

Abdomen

[Myxedema coma].

Explore the source record for details and available documents.

Aged