Local hyperthermia induced by focussed and overlapping ultrasonic fields--an in vivo demonstration.

Axial temperature distributions were measured in living and post mortem porcine tissues during sonication with plane, focussed and overlapping ultrasonic fields. With the focussed field it was always possible to induce the temperature maxima at depths up to 50 mm, although the actual temperatures achieved varied from animal to animal. The plane 0.

The construction and assessment of lenses for local treatment of malignant tumours by ultrasound.

A simple method to build ultrasound lenses from araldite has been developed. The focussing properties of these lenses as a function of sonic frequency and lens diameter were studied using a computer model. The optimum frequency and diameter of these lens were found to be around 1 MHz and between 40 and 60 mm respectively, for deep tissue heating.

Diazepam dosage and timing in ketamine combination anaesthesia. A double-blind study.

A form of combination anaesthesia using ketamine, diazepam, alcuronium and nitrous oxide was used in 41 patients over 65 years requiring abdominal surgery. The patients were premedicated with droperidol 2.5-7.

The effects of some physical factors on the production of hyperthermia by ultrasound in neoplastic tissues.

A one-dimensional and a three-dimensional computer model have been built in order to study the importance of blood flow and ultrasonic absorption in tissues during local hyperthermia. The decreased blood flow in the interior of certain tumours and possibly the increased ultrasonic absorption of the malignant tissue in some cases may cause selectively higher temperatures inside the tumours though the heat input is the same as in the surrounding tissues. Also, the vasodilation of blood vessels in normal tissues as a response to heat causes a therapeutically useful temperature difference.

Erythrocyte damage caused by the Haemotherm microwave blood warmer.

Blood units (59) were warmed with the Haemotherm microwave blood warmer and seven units were warmed in a water bath for comparison. The influence of the final blood temperature, the size and the hematocrit of the units on the erythrocyte lesion was studied. Extracellular hemoglobin and potassium, hematocrit, osmotic fragility and mean cellular volume were used as indicators of red cell damage.