The present study examined to what extent an acute bout of hypotension influences blood flow in the external carotid artery (ECA) and the corresponding implications for blood flow regulation in the internal carotid artery (ICA). Nine healthy male participants were subjected to an abrupt decrease in arterial pressure via the thigh-cuff inflation-deflation technique. Duplex ultrasound was employed to measure beat-to-beat ECA and ICA blood flow. Compared with the baseline normotensive control, acute hypotension resulted in a heterogeneous blood flow response. ICA blood flow initially decreased following cuff release and then returned quickly to baseline levels. In contrast, the reduction in ECA blood flow persisted for 30 s following cuff release. Thus, the contribution of common carotid artery blood flow to the ECA circulation decreased during acute hypotension (-10 ± 4%, P < 0.001). This finding suggests that a preserved reduction in ECA blood flow, as well as dynamic cerebral autoregulation likely prevent a further decrease in intracranial blood flow during acute hypotension. The peripheral vasculature of the ECA may, thus, be considered an important vascular bed for intracranial cerebral blood flow regulation.

Patients with chronic obstructive pulmonary disease admitted to the ICU for acute exacerbations had abnormal breathing-swallowing interactions and dyspnea, which improved with noninvasive mechanical ventilation. Furthermore, a ventilator device with a simple switch-off pushbutton to eliminate insufflations during swallows prevented swallowing-induced ventilator triggering and postswallow autotriggering.

Background: Inspiratory muscle strength measurements have become a cornerstone in monitoring neuromuscular disorders. Usually, sniff nasal inspiratory pressure (SNIP) and maximal inspiratory pressure (MIP) are performed. To our knowledge the session-to-session learning effect has rarely been evaluated for MIP performance and has never been done for SNIP performance. Objectives: We hypothesized that the sniff manoeuvre was natural and did not need to be learned, whereas the Muller manoeuvre, used for MIP measurement, was an isometric contraction which needed to be learned because it is rarely performed in real life conditions. This hypothesis suggests that from the first session and continuing through a subsequent one, the maximal SNIP value and the number of sniff trials necessary to attain it are more reproducible than the maximal MIP value and the number of Muller manoeuvre trials necessary to attain it. Methods: Seventy-one healthy subjects were included. SNIP and MIP manoeuvres were repeated 12 and 6 times, respectively, per week during 2 sessions a week apart. Results: We observed a session effect on MIP but not on SNIP. Maximal value for MIP was higher during the second session, whereas SNIP maximal value did not increase during the second session. The number of trials needed to obtain the maximal value for MIP was lower during the second session whereas it was not different for SNIP. Conclusions: SNIP is less sensitive to a learning effect than is MIP. It requires only a routine warm-up. We suggest that SNIP is preferable to MIP for repeated measurement of inspiratory muscle performance.