BEDSIDE NUCLEAR-MEDICINE INVESTIGATIONS IN THE INTENSIVE-CARE UNIT

The functional nature of nuclear medicine procedures makes them especi ally valuable in the management of patients undergoing intensive care. However, the severe nature of the patient's condition invariably prev ents him or her from attending the nuclear medicine department for dia gnostic investigations. We have piloted a bedside nuclear medicine ser vice using a four-probe detector system linked to an IBM computer with curve professing software. Protocols for a range of radionuclide prob e investigations, including renal, hepatobiliary, gastric outflow and lung vascular permeability, using Tc-99(m) and In-111 radiopharmaceuti cals have been established. The measurement of lung vascular permeabil ity in patients with clinical symptoms of adult respiratory distress s yndrome was considered to be a valuable procedure on the intensive car e unit. Due to the poor availability of In-113(m), which had previousl y been used for the measurement of lung permeability, we used a techni que based on in vivo labelling of serum transferrin with In-111-chlori de together with Tc-99(m)-red blood cells for the calculation of the p lasma protein accumulation index. Other procedures include the measure ment of gastric outflow in patients previously on parenteral feeding, and the assessment of hepatobiliary and renal function. The equipment proved to be reliable and convenient for use at the bedside, although ultrasound imaging was essential for the correct positioning of the pr obe detectors over smaller organs such as the kidneys and the gallblad der. The high sensitivity of the probe detectors required only low adm inistered amounts of activity, minimizing radiation protection measure s for patients and staff. The administration of radiopharmaceuticals v ia indwelling lines and tubes presented particular problems and we rec ommend that parenteral injections should not be given through manifold giving sets, or via Tenon cannulae.