Abstract: In a hematology measurement apparatus, a hematocrit value is generated by incrementing a value in accumulation means in accordance with measured sizes of red blood cells. The hematocrit value is corrected for coincidence by incrementing the value additionally in response to the production of red blood cell count coincidence corrections pulses.

Abstract: In an automatic chemical testing apparatus in which radiant energy readings are taken from a liquid sample of reacted contents comprising reagent and one or more aliquots, one per channel, of a sample fluid, a statistically large number of readings are taken on each sample. For example, in a readout cycle, 32 readings are taken on each channel for a sample. For an end point chemistry, calculation of an output value is based on the mean of a plurality of readings which are a subset of all readings. For a kinetic chemistry, the output reading is based on a slope of a curve defined by subsets of successive readings.

Abstract: An improved reagent system for chemical determinations and novel compositions therefor provide improved reagent stability, particularly in a dry, storage stable phase. For determinations in which hexokinase and glucose-6-phosphate dehydrogenase are indicator enzymes, glycine and taurine are combined with bovine serum albumin to provide a bulking agent for the indicator enzymes which also acts as a stabilizer. A novel salt, the tris (hydroxymethyl)aminomethane salt of 2 mercaptosuccinic acid, acts as an activator or stabilizer in chemistries utilizing the indicator enzymes, namely determinations of creatine phosphokinase or glucose. The novel salt also acts as a stabilizer in a urea nitrogen determination. Dry reagent components are bulked in triethanolammonium terepthalate. Novel CPK, glucose and serum urea nitogen determinations are also provided.

Abstract: A fail safe detector in a cardiac monitoring system provides an alarm to indicate failure of the system to respond to cardiac waveforms supplied thereto from cardiac waveform sources. A time out circuit will produce the alarm if not periodically reset by pulses produced in response to measurement of cardiac waveforms. Means are provided for sensing whether cardiac waveforms are received from the sources to provide an alternate means of triggering periodic reset signals when no waveforms are received from the sources to prevent false alarms.