Assessing the role of cerebral autoregulation during intrathoracic pressure changes by near infrared spectroscopy (NIRS)

Changes in intrathoracic pressure in obstructive sleep apnea have strong intermittent effects on oxygenation of hemoglobin and left ventricular stroke volume. While compensatory systemic mechanisms are well studied the role of cerebral autoregulation remains essentially unknown. We aimed to compare hemodynamic response in muscle and brain assessed by NIRS during Valsalva- and Müller- maneuvers (VM respectively MM) and thereby describing the role of cerebral autoregulation.In five healthy adults cerebral and muscular NIRS and esophageal pressure (EP) were continuously measured during normal breathing, two VM (EP +15/+30cmH2O) and two MM (EP -15/-30cmH2O). We compared NIRS-signal regarding relative changes in oxygen saturation [SO2] and total hemoglobin [tHb] and in particular the area under the pulse-wave-curve of tHb which is thought to reflect left ventricular stroke volume.In both VM and more pronounced in MM a decrease in SO2 and a subsequent increase with event resumption was seen while tHb increased during VM and decreased during MM. During the latter phase in both sustained MM and VM the area under the pulse-wave-curve in tHb was reduced. Relative decrease of SO2 was attenuated in brain compared to muscle indicating compensatory cerebral autoregulation in response to intrathoracic pressure changes.Cerebral and muscular hemodynamic changes can be monitored non-invasively by NIRS. Comparison of the muscular and cerebral NIRS-signal is a promising tool to describe ...
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: 4.2 Sleep and Control of Breathing Source Type: research