Hemodynamic changes after hypothalamic and brain stem surgery: interdisciplinary approach to studying

Introduction

We discuss prognostic criteria of hemodynamic changes in patients after hypothalamic and brain stem surgery. We hope that better understanding of mechanisms of adaptive disorders in local brain lesions will help to optimize postoperative management of these patients. This study was based on the interdisciplinary neurocardiologic approach [1].

Methods

Cardiac output measured by the echocardiographic method as well as hemodynamic and humoral parameters were investigated in 139 patients with pituitary adenomas and craniopharyngiomas and in 148 patients with brain stem tumors.

Results

We consider that unfavorable hemodynamic changes may be used as prognostic criteria of severe damage of regulatory centers in the hypothalamus or brain stem. It is clear that a favorable type of hemodynamic change is a kind of postoperative stress reaction. The reaction after pituitary tumor surgery was reduced or delayed and grew to its peak by the third day after brain stem surgery. The main unfavorable type of hemodynamics was decreased cardiac output (CO). However, the causes of this decrease are quite different. In damage of the hypothalamus, decrease of CO was connected with decreased blood volume and the latter was connected with a decrease of vasopressin secretion. Our research has shown that patients with lesions of different structures of the hypothalamus and brain stem revealed specific changes of various neurohumoral systems. In damage of the dorsomedial part of the medulla oblongata, the decease of CO was caused by primary neurogenic cardiac insufficiency. In damage of hypothalamic structures, we see increased amplitude power spectral density of the respiratory period of heart rate variability (HRV), a decrease of the amplitude of the low-frequency peak and a very high degree of coherence between HRV and respiratory variability. In brain stem structure damage, we can see low-frequency components only on the power spectral density of HRV. We postulate that the revealed distinctions of power spectral density of HRV showed that with hemodynamic disturbance in hypothalamic and brain stem lesions a different pathological type of cerebral regulation of hemodynamics forms.

Conclusion

Disorders of a humoral regulation at focal lesions of the hypothalamus and brain stem are specific. Intensive care should therefore be carried out taking into account that these changes should be directed to regeneration of a normal humoral pattern.