RESPIRATORY AND CARDIOVASCULAR CHANGES DURING RAPID SPONTANEOUS VARIATIONS OF VENTRICULAR FLUID PRESSURE IN PATIENTS WITH INTRACRANIAL HYPERTENSION

Abstract

In patients with intracranial hypertension the ventricular fluid pressure (VFP) curve is characterized by 3 main forms of spontaneous variations. Two of these forms are of a rhythmical nature and are here called 1-per-minute waves and 6-per-minute waves, respectively, in accordance with the dominating frequency. The 3rd form [long dash]irregularly appearing waves of large amplitude and duration-is called plateau waves in accordance with the usual shape of the fluctuations. Respiratory and cardiovascular changes accompanying these variations of the VFP were studied by simultaneous recording in various combinations, of the VFP, the pulmonary ventilation, the pCO2 of the expiratory air, the arterial and the venous blood pressure, and the pulse frequency. It was found that the rhythmic VFP variations of the 1-per-minute type occurred synchronously with the respiratory periods in Cheyne-Stokes breathing. Synchronously appearing variations in systemic blood pressure, in pulse frequency, as well as in consciousness and in muscular tone of the limbs were also noted. The respiratory midposition shifted towards the inspiratory side during the periods of hyperpnoea. The 6-per-minute waves were entirely synchronous with variations in the systemic arterial blood pressure of the Traube-Hering-Mayer type. Long sequences of these waves were observed only when the VFP level was considerably elevated. The plateau waves were not accompanied by corresponding elevations of the arterial or venous systemic blood pressure. Simultaneously with the crests of the plateau waves sudden changes often occurred in the pulse frequnecy (from bradycardia to tachycardia) and in the respiratory pattern, sometimes also in the degree of consciousness and in the muscular tone. There was also long sequences of 6-per-minute waves. The deep, irregular breathing seen in this stage induced a considerable hypocapnia preceeding the final critical fall in the VFP ending the plateau wave. In most instances, however, this fall did not begin until several minutes after the appearance of the hypocapnia.