A new anechoic material for medical ultrasonic applications.

This paper describes a newly developed material with acoustic properties that make it ideal for applications as radiation force balance-absorbing targets. The material is now commercially available from National Physical Laboratory (NPL) and is based on a polyurethane rubber. It exhibits an echo reduction of 45 dB, and single-pass transmission loss of 30 dB, both determined at an acoustic frequency of 1 MHz. The composition and structure of the new NPL absorber are presented, along with values for the frequency and temperature variation of the echo reduction and transmission loss. Over the frequency range 1 to 10 MHz, its acoustic properties comply with the requirements for force balance-absorbing targets specified in IEC 61161.

Distal decompression and proximal feeding for nutritional support during bowel obstruction.

The treatment for acute mechanical intestinal obstruction is a timely operation. A select group of patients may, however, be nutritionally supported with continual administration of elemental diet proximal to long tube decompression under two sets of circumstances: 1. while awaiting spontaneous or treatment-induced resolution of the underlying process, and 2. while reversing catabolism during evaluation prior to operation. Eleven patients with chronic intermittent bowel obstruction were studied: six with obstruction involving radiated small bowel, three with an acute exacerbation of chronic inflammatory bowel disease, one with obstruction secondary to an intra-abdominal phlegmon and one with a segmental motility problem. They received nutritional support with continual gastrointestinal administration of elemental diet proximal to long tube decompression after initial observation for signs or symptoms of altered intestinal viability and stabilization of fluid and electrolyte status. Six of the 11 patients eventually required operation. All patients maintained body weight and three gained weight. Mean nutritional input was 1,873 calories and 12.6 gm nitrogen/day. There were no complications related to the technique of proximal feeding and distal decompression because of careful patient selection and appropriate administration of elemental diet under carefully controlled guidelines.