Physiological measurement
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Physiological measurement · Jul 2017
Gender differences in severity of desaturation events following hypopnea and obstructive apnea events in adults during sleep.
Severity estimation of obstructive sleep apnea (OSA) is currently based on the apnea-hypopnea index (AHI), which ignores individual breathing cessation event characteristics. Gender differences in the relationship between the breathing cessation event duration and the related desaturation event severity could mean that the severity of OSA is different in males and females despite a similar AHI. The aim of this work was to evaluate gender differences in the severity of peripheral oxygen desaturation events following obstructive apneas or hypopneas. ⋯ We found gender differences in the desaturation event severities following obstructive apneas and hypopneas. The results indicate that in females longer obstructive apneas (>30 s) could be more detrimental compared to those of males. As severe health consequences are related to the desaturation severity these aspects should be considered when estimating the severity of OSA.
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Physiological measurement · Jul 2017
Invasive and noninvasive means of measuring intracranial pressure: a review.
Measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Cerebrospinal fluid is produced by the choroid plexus in the brain ventricles (a set of communicating chambers), after which it circulates through the different ventricles and exits into the subarachnoid space around the brain, where it is reabsorbed into the venous system. If the fluid does not drain out of the brain or get reabsorbed, the ICP increases, which may lead to brain damage or death. ICP elevation accompanied by dilatation of the cerebral ventricles is termed hydrocephalus, whereas ICP elevation accompanied by normal or small ventricles is termed idiopathic intracranial hypertension.
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Physiological measurement · Jun 2017
Consecutive ultra-short-term heart rate variability to track dynamic changes in autonomic nervous system during and after exercise.
Quantitative measurement of the dynamic changes in autonomic nervous system (ANS) during and after exercise has great significance in clinical, sports training and other fields. A consecutive ultra-short-term (30 s, UST) heart rate variability (HRV) method was proposed to track the exercise-induced autonomic control of heart rate (HR). ⋯ Compared with the indices in frequency domain, the Poincaré indices were more sensitive and accurate in UST measurement of ANS during exercise. The results demonstrated that the UST method could characterize the dynamic changing tendency of ANS during and after exercise and quantify the differences of changes in ANS induced by exercise with different intensities. In particular, the vagal branch functioned dominantly in controlling HR in S0 but the effect of the sympathetic branch on HR enhanced with the increase of exercise intensity. In addition, the transient changes of ANS related with the sudden onset of exercise could also be reflected, despite perhaps being limited by the computation window width to some extent. Thus, the consecutive UST Poincaré indices could provide a feasible and simple method to measure quantitatively the exercise-induced dynamic changes in ANS.
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Physiological measurement · Jun 2017
Observational StudyCerebral hemodynamics with intra-aortic balloon pump: business as usual?
Intra-aortic balloon pump (IABP) is commonly used as mechanical support after cardiac surgery or cardiac shock. Although its benefits for cardiac function have been well documented, its effects on cerebral circulation are still controversial. We hypothesized that transfer function analysis (TFA) and continuous estimates of dynamic cerebral autoregulation (CA) provide consistent results in the assessment of cerebral autoregulation in patients with IABP. ⋯ IABP does not disturb cerebral hemodynamics. TFA and continuous estimates of dynamic CA can be used to assess cerebral hemodynamics in patients with IABP. These findings have important implications for the design of studies of critically ill patients requiring the use of different invasive support devices.
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Physiological measurement · Jun 2017
Global and regional assessment of sustained inflation pressure-volume curves in patients with acute respiratory distress syndrome.
Static or quasi-static pressure-volume (P-V ) curves can be used to determine the lung mechanical properties of patients suffering from acute respiratory distress syndrome (ARDS). According to the traditional interpretation, lung recruitment occurs mainly below the lower point of maximum curvature (LPMC) of the inflation P-V curve. Although some studies have questioned this assumption, setting of positive end-expiratory pressure 2 cmH2O above the LPMC was part of a 'lung-protective' ventilation strategy successfully applied in several clinical trials. The aim of our study was to quantify the amount of unrecruited lung at different clinically relevant points of the P-V curve. ⋯ Our results confirm the notion of ongoing lung recruitment at pressure levels above LPMC for all investigated model equations and highlight the importance of a regional assessment of lung recruitment in patients with ARDS.