The application of a non-imaging nuclear probe system to the critically ill: laboratory validation and a clinical trial.

Non-imaging nuclear probe systems have been available for bedside monitoring of left ventricular function since the early 1970s. The purpose of this study was to evaluate a recently developed system, the Cardioscint (Oakfield Instruments, Oxford, UK), both in the laboratory and clinically prior to its application in the critically ill on the intensive care unit. The probe system was stable at body temperature for prolonged periods and its count rate capability was adequate for those encountered clinically. An adequate period of data acquisition was shown to be important because random isotope decay produces a significant noise at these count rates. Left ventricular ejection fraction in patients with symmetrical ventricular contraction agree closely with the results obtained with radionuclide ventriculography (mean difference = 0.98%, S.D. = 2.8%, n = 30). However, in patients with asymmetrical ventricular contraction the agreement is poor (mean difference = -3.0%, S.D. = 6.2%, n = 10).