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Biomedical subjects

A Hald

Publications and source records attributed to A Hald.

9 recordsLinked to original sources
PubMed1989

Assessing the position of the tracheal tube. The reliability of different methods.

Various methods have been developed to confirm proper intubation of the trachea. This blind, randomised study evaluates some of these quantitatively and qualitatively. Forty patients had both their trachea and oesophagus intubated. A procedure that included auscultation of the upper abdomen and lungs was 100% reliable independent of which tube was ventilated. Auscultation of the lungs resulted in a wrong conclusion in 15% (6-30, 95% confidence limits) of the cases when the oesophagus was ventilated: the sounds were misinterpretated as normal breath sounds. Suction on the tubes with a 60-ml syringe was also a reliable test. Other methods assessed were observation for condensation of water vapor, and abnormal movements of the upper abdomen; these were unreliable.

Anesthesia, General↗
PubMed1986

Ketanserin and malignant hyperthermia in pigs.

Four Danish landrace pigs susceptible to MH were challenged with halothane and suxamethonium on six occasions after pretreatment with the serotonin-S2 antagonist ketanserin 0.4 mg/kg (three animals) or 4 mg/kg (three animals). The animals developed typical MH on all occasions despite the pretreatment. Dantrolene remains the only specific drug for prevention and treatment of MH.

Animals↗
PubMed1985

Malignant hyperthermia triggered by heating in anaesthetized pigs.

Three malignant hyperthermia susceptible (MHS) and three normal Danish landrace pigs were heated using a water-heated mattress, warm blankets and warm intravenous saline during anaesthesia with barbiturate and 50% nitrous oxide in oxygen. The MHS pigs developed typical malignant hyperthermia (MH) at a rectal temperature of 41.0 +/- 0.7 degrees C, whereas the normal pigs tolerated heating to the same temperature without any ill effects. Haemodynamic and metabolic findings during MH were similar to those previously reported for anaesthetic-induced MH in pigs. Heat intolerance may thus be one factor in the genesis of MH.

Anesthesia↗
PubMed1983

Pulmonary angiotensin II production in respiratory failure.

Plasma angiotensin II concentration gradients across the pulmonary vascular bed, plasma renin concentration and serum converting enzyme activity were measured in 19 patients. The majority of the patients were critically ill. Nine patients had septicemia with acute respiratory failure, six patients had severe chronic lung disease and four patients had other serious disorders requiring haemodynamic monitoring. Pulmonary angiotensin II generation rates were calculated as the products of the pulmonary plasma flow and the angiotensin II concentration gradient across the lung. Several patients had a highly activated renin-angiotensin system. There was a strictly linear correlation between the plasma angiotensin II concentrations in mixed venous blood and in systemic arterial blood across a wide range, the concentration in arterial blood being 1.4-1.5 times that in mixed venous blood in each of the three groups of patients. Serum converting enzyme activity was not different from the level observed in a group of control patients above 50 years of age, but lower than in younger normal individuals. The maximal angiotensin II production rates in the pulmonary vascular bed of patients with life-endangering pulmonary disease were similar to the rates previously measured in hypertensive patients with renovascular or renal parenchymal disease. In conclusion, the process of angiotensin I conversion in the lung operates without impediment in spite of severe pulmonary injury.

Adolescent↗
PubMed1982

A method for selective endobronchial and endotracheal irradiation.

A method for selective endobronchial and endotracheal irradiation is described. This method was used to treat a young woman with an unresectable adenoid cystic carcinoma of the trachea involving the main bronchi. The treatment provided good palliation, as indicated by increase of maximal breathing capacity (MBC) and forced expiratory volume in the first second (FEV1.0).

Adult↗
PubMed1980

Computerized hot-wire anemometry--principles of calculation.

Principles of calculation of respiratory parameters based on a hot-wire anemometer with special reference to computer monitoring were evaluated. Flow-rate, gas-pressure, and flow-direction signals were recorded simultaneously on magnetic tape. Subsequent quantitative analyses were performed on a general purpose digital minicomputer. An analysis epoch of 256 s was selected from the 3 channels. After identification of one cycle baseline values of flow-rate and pressure were determined. Different time-lags in one respiratory cycle (inspiratory time, pause time and expiratory time) could be determined. Inspiratory and expiratory volumes were obtained by integration. Peak of the thoracic cage and the lungs were calculated using the above mentioned parameters. Finally, the respiratory frequency was calculated.

Airway Resistance↗
PubMed1979

A new transducer for respiratory monitoring. A description of a hot-wire anemometer and a test procedure for general use.

A respiratory transducer based on the constant temperature anemometry principle has been developed for respiratory monitoring, and as a tool for bedside evaluation of pulmonary function. The transducer is characterized by a dynamic range from 0-2.5 1/s and an upper limiting frequency of 50 Hz. It is designed with a view to a low pressure drop of 2.5 mbar/1/s and a minimum dead space of 5 ml. The transducer has been tested using a generally applicable procedure which includes both static and dynamic test set-ups. The influence of variation in gas composition, temperature and pressure, together with variations in tidal volume and respiration rate, have been investigated. The results show that the transducer registers the immediate value of gas flow-rate with a mean error less than 5-10% in all situations which are predictable in clinical use. The mean error can be reduced to less than 5% when systematic errors are eliminated.

Anesthesia, General↗