Computer model study of regulatory mechanisms during airway obstruction

The baroreflex regulation counteracts with the systemic autoregulation in controlling the arterial resistance: baroreflex attempts to maintain a certain arterial pressure and systemic autoregulation attempts to maintain a certain cardiac output. In addition, baroreflex also controls heart rate and myocardial contractility based on arterial pressure changes. A computer model based on an electrical circuit has been developed and helped studying various cardiopulmonary mechanisms in health and disease. The model was capable of correctly predicting the hemodynamic consequences by incorporating simple baroreflex and autoregulatory gains and further suggested that baroreflex regulation slightly dominates autoregulation. With a postulation that baroreflex of heart rate is the major determinant, this study examined how the model fitted hemodynamic data obtained from humans with or without these regulation mechanisms. Twenty two patient data sets obtained retrospectively were used and classified into young and older group. Due to severe airway obstruction, inspiratory fall of arterial pressure was magnified as 31/spl plusmn/10 mmHg for the young and 29/spl plusmn/12 mmHg for the old. The performance of the model was accessed by comparing simulated arterial pressure and clinical data. With a simple linear model of baroreflex function on heart rate, the performance was noticeably increased: correlation coefficients (t) were 0.87plusmn;0.06 (mean/spl plusmn/SD). Baroreflex effects on total peripheral resistance and ventricular contractility were also evaluated, but much less significant than those from the heart rate regulation.