Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 2021
Context-sensitive decrement times for inhaled anesthetics in obese patients explored with Gas Man®.
Anesthesia care providers and anesthesia decision support tools use mathematical pharmacokinetic models to control delivery and especially removal of anesthetics from the patient's body. However, these models are not able to reflect alterations in pharmacokinetics of volatile anesthetics caused by obesity. The primary aim of this study was to refine those models for obese patients. ⋯ With increasing obesity, recovery and resolution times were higher. The additional adipose tissue in obese simulation models did not prolong awakening times and thus may act more like a sink for volatile anesthetics. The results of these simulations should be validated by comparing the elimination of volatile anesthetics in obese patients with data from our simulation models.
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J Clin Monit Comput · Apr 2021
Randomized Controlled TrialPhotoplethysmography-derived approximate entropy and sample entropy as measures of analgesia depth during propofol-remifentanil anesthesia.
The ability to monitor the physiological effect of the analgesic agent is of interest in clinical practice. Nonstationary changes would appear in photoplethysmography (PPG) during the analgesics-driven transition to analgesia. The present work studied the properties of nonlinear methods including approximate entropy (ApEn) and sample entropy (SampEn) derived from PPG responding to a nociceptive stimulus under various opioid concentrations. ⋯ The result showed that low Ceremi (0 and 1 ng·ml-1) could be differentiated from high Ceremi (3 and 5 ng·ml-1) by ApEn and SampEn. Depending on the coefficient employed in algorithm: ApEn with k = 0.15 yielded the largest PK value (0.875) whereas SampEn gained its largest PK of 0.867 with k = 0.2. Thus, PPG-based ApEn and SampEn with appropriate k values have the potential to offer good quantification of analgesia depth under general anesthesia.
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J Clin Monit Comput · Apr 2021
Ocular blood flow by laser speckle flowgraphy to detect cerebral ischemia during carotid endarterectomy.
Laser speckle flowgraphy (LSFG) is a noninvasive technique that can measure relative blood flow velocity in the optic fundus contributed by the ophthalmic artery, the main first branch originating from the internal carotid artery (ICA). The aim of this study was to assess the feasibility of ocular blood flow measurement by LSFG to detect ischemic stress due to carotid clamping during carotid endarterectomy (CEA). Nineteen patients undergoing CEA with ocular blood flow measurement by LSFG and intraoperative monitoring (IOM) were prospectively enrolled between August 2016 and March 2019. ⋯ The MBR reduction ratio was positively correlated with the rSO2 index (r = 0.694, 95% confidence interval: 0.336-0.877, p = 0.001). The MBR reduction ratio of ocular blood flow by LSFG after carotid clamping was significantly correlated with the rSO2 index. The ocular blood flow by LSFG could be considered an adjunct modality for evaluating cerebral ischemic tolerance during CEA.
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J Clin Monit Comput · Apr 2021
Continuous and entirely non-invasive method for cerebrovascular reactivity assessment: technique and implications.
Continuous cerebrovascular reactivity assessment in traumatic brain injury (TBI) has been limited by the need for invasive monitoring of either cerebral physiology or arterial blood pressure (ABP). This restricts the application of continuous measures to the acute phase of care, typically in the intensive care unit. It remains unknown if ongoing impairment of cerebrovascular reactivity occurs in the subacute and long-term phase, and if it drives ongoing morbidity in TBI. ⋯ Recent advances in continuous high-frequency non-invasive ABP measurement, combined with NIRS or rTCD, can be employed to derive continuous and entirely non-invasive cerebrovascular reactivity metrics. Such non-invasive measures can be obtained during any aspect of patient care post-TBI, and even during outpatient follow-up, avoiding classical intermittent techniques and costly neuroimaging based metrics obtained only at specialized centers. This combination of technology and signal analytic techniques creates avenues for future investigation of the long-term consequences of cerebrovascular reactivity, integrating high-frequency non-invasive cerebral physiology, neuroimaging, proteomics and clinical phenotype at various stages post-injury.
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J Clin Monit Comput · Apr 2021
Observational StudyOscillometric versus invasive blood pressure measurement in patients with shock: a prospective observational study in the emergency department.
In emergency medicine, blood pressure is often measured by an oscillometric device using an upper arm cuff. However, measurement accuracy of this technique in patients suffering from hypotensive shock has not been sufficiently evaluated. We designed a prospective observational study investigating the accuracy of an oscillometric device in hypotensive patients admitted to the resuscitation area of the emergency department. ⋯ In 64% of readings, values obtained by the upper arm cuff were not able to detect hypotension. Oscillometric blood pressure measurement is not able to reliably detect hypotension in emergency patients. Therefore, direct measurement of blood pressure should be established as soon as possible in patients suffering from shock.