Summary Derangements in the circulation are a common feature of sepsis, trauma, major surgery and other critical illnesses. Detailed evaluation of the circulation is therefore an essential aspect of the clinical management of such patients. The use of cardiac output monitoring technology is an increasingly important aspect of evaluating patients in the operating theatre, critical care unit and elsewhere. There are now a number of different technologies available for this purpose, which use a diverse range of physiological principles. A detailed understanding of the physiological principles applied by such technology is essential for safe and effective use in clinical practice. The aim of this article is to describe the physiological principles used to measure cardiac output and their application in various monitors in common clinical use.

Sedation in sea lions exhibiting abnormal neurologic signs may require modification of established sedation protocols because of the likely interaction between effects of the sedative and physiologic changes in diseased animals. The effects of two sedative combinations, 0.07 mg/kg medetomidine and 0.07 mg/kg medetomidine plus 0.2 mg/kg butorphanol, were compared between California sea lions (Zalophus californianus) with signs of neurologic dysfunction (n = 33) and without neurologic signs (n = 8). Sedation depth was scored on a scale of 0 (no effect) to 4 (profound sedation) assessed by response to auditory, tactile, and visual stimuli at the time of perceived maximal sedative effect. In the medetomidine-alone group, sea lions with neurologic signs attained a median sedation score of 4 compared to a median sedation score of 1 in the clinically normal sea lions. Sea lions with and without neurologic signs given medetomidine–butorphanol attained a median sedation score of 4. No statistically significant difference in time to induction and respiratory rate was found between the two sedation protocols in all sea lions. In the sea lions with neurologic signs, the recovery time from medetomidine–butorphanol sedation was prolonged (P < 0.01) and minimum recorded heart rates, although remaining within normal physiologic limits, were lower (P = 0.02) when compared to the sea lions administered medetomidine alone. Muscle jerks were observed in many animals given medetomidine–butorphanol and were detrimental to the diagnostic quality of the electroencephalogram (EEG) recording. Medetomidine alone at a dose rate of 0.07 mg/kg thus provides adequate and safe sedation in sea lions with neurologic signs undergoing EEG evaluation.

No abstract

No abstract

A method is described of compiling X-ray diagnostic exposure tables which give exposure factors for a given patient physique. The necessary calculations are based on the method of least squares and have been programmed for an I.C.T. Pegasus digital computer.