No abstract
An evaluation of the influence of sex upon cerebral atherosclerosis was carried out in 5,033 consecutive autopsies studied by a special well-standardized coding technique. A sex difference in frequency of cerebral atherosclerosis appears from the fourth to the sixth decade. During this period the percentage of female cases with no atherosclerosis lags behind the percentage of male cases by a 15-year period. After the sixth decade, the frequency of cerebral atherosclerosis increases more rapidly in females, so that beyond the age of 65 years the frequency of cerebral atherosclerosis is equal in the two sexes. Furthermore, younger males show a higher degree of cerebral atherosclerosis than females of the same age and a reverse trend appears in the oldest age groups. Diabetic females have more cerebral atherosclerosis than nondiabetic males, and beyond the fourth decade they have at least as much involvement as the diabetic males.
The effects of halothane (1.0-1.5%) on myocardial contractility, systemic vascular resistance (representing the majority of impedance to oscillatory flow), and left ventricular performance, and the interactions of these functions have been studied in openchested dogs, artificially ventilated and maintained in a state of basal narcosis with chloralose and urethane. Halothane reversibly depressed myocardial contractility as estimated by three indices: maximum left ventricular (dP/dt)/IP, maximum left ventricular (dP/dt)/PCIP, and maximum aortic acceleration, but produced no significant changes of left ventricular end-diastolic pressure or of systemic vascular resistance. Stroke volume fell in proportion to the depression of myocardial contractility at constant heart rates maintained by atrial pacing, though the reduction of stroke volume was greatest when systemic vascular resistance increased slightly. The concept is proposed that, irrespective of minor changes in the peripheral venous bed during halothane anaesthesia, depression of myocardial contractility impairs ventricular emptying rather than ventricular filling. This concept is based on the observation that since peak aortic flow and acceleration are decreased during halothane anaesthesia, the force acting on blood and the momentum imparted to it during the early phase of ventricular ejection are reduced. Experimental evidence supported this hypothesis: thus, when the contractility of the myocardium was depressed by halothane anaesthesia, independent changes of systemic vascular resistance significantly modified the stroke output of the heart. It is concluded that the major cause of arterial hypotension during halothane anaesthesia is a fall in cardiac output, and that the predominant mechanism causing this fall is the depression of myocardial contractility. Halothane has justifiably achieved wide popularity of both. In searching for a predominant cardiovasin clinical use, and yet, despite the wide range of cular action of halothane in animals, Price and Price both clinical and experimental studies of its actions, (1966) concluded that there was no single or predothere is still uncertainty about its effects on the minant cause for the circulatory depression produced cardiovascular system. While most observers are by halothane. Further studies have conclusively agreed that halothane causes a dose-dependent arte-demonstrated that in concentrations which are assorial hypotension in most species, not all are agreed ciated with surgical anaesthesia, halothane decreases as to whether in man this is predominantly the the myocardial contractile force in both man result of reduced cardiac output (Severinghaus and
SummaryThe incidences of mortality and morbidity associated with anaesthesia were reviewed. Most of the published incidences for common complications of anaesthesia vary considerably. Where possible, a realistic estimate of the incidence of each morbidity has been made, based on the best available data. Perception of risk and communication of anaesthetic risk to patients are discussed. The incidences of anaesthetic complications are compared with the relative risks of everyday events, using a community cluster logarithmic scale, in order to place the risks in perspective when compared with other complications and with the inherent risks of surgery. Documentation of these risks and discussion with patients should allow them to be better informed of the relative risks of anaesthetic complications. Depending on specific comorbidities and the severity of operation, these risks associated with anaesthesia may increase for any one individual.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.