Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2015
Comparative StudyValidation of stroke volume and cardiac output by electrical interrogation of the brachial artery in normals: assessment of strengths, limitations, and sources of error.
The goal of this study is to validate a new, continuous, noninvasive stroke volume (SV) method, known as transbrachial electrical bioimpedance velocimetry (TBEV). TBEV SV was compared to SV obtained by cardiac magnetic resonance imaging (cMRI) in normal humans devoid of clinically apparent heart disease. Thirty-two (32) volunteers were enrolled in the study. ⋯ Bland-Altman analysis of averaged pre- and post-cMRI TBEV CO versus cMRI CO yielded a mean bias of 5.01% (0.32 L min(-1)), precision of 12.85% (0.77 L min(-1)), 95% LOA of +30.20 % (+0.1.83 L min(-1)) and -20.7% (-1.19 L min(-1)) and percent error = 24.8%. Regression analysis yielded y = 0.92x + 0.78, correlation coefficient r(2) = 0.74 (r = 0.86). TBEV is a novel, noninvasive method, which provides satisfactory estimates of SV and CO in normal humans.
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J Clin Monit Comput · Dec 2015
Evaluation of near-infrared spectroscopy under apnea-dependent hypoxia in humans.
In this study we investigated the responsiveness of near-infrared spectroscopy (NIRS) recordings measuring regional cerebral tissue oxygenation (rSO2) during hypoxia in apneic divers. The goal was to mimic dynamic hypoxia as present during cardiopulmonary resuscitation, laryngospasm, airway obstruction, or the "cannot ventilate cannot intubate" situation. Ten experienced apneic divers performed maximal breath hold maneuvers under dry conditions. ⋯ Cerebral rSO2 measured re-saturation after termination of apnea significantly earlier (10 s, SD = 3.6 s) compared to SpO2 monitoring (21 s, SD = 4.4 s) [t(9) = 7.703, p < 0.001, r(2) = 0.868]. Our data demonstrate that NIRS monitoring reliably measures dynamic changes in cerebral tissue oxygen saturation, and identifies successful re-saturation faster than SpO2. Measuring cerebral rSO2 may prove beneficial in case of respiratory emergencies and during pulseless situations where SpO2 monitoring is impossible.
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J Clin Monit Comput · Dec 2015
Effect of planecta and ROSE™ on the frequency characteristics of blood pressure-transducer kits.
Pressure-transducer kits have frequency characteristics such as natural frequency and damping coefficient, which affect the monitoring accuracy. The aim of the present study was to investigate the effect of planecta ports and a damping device (ROSE™, Argon Medical Devices, TX, USA) on the frequency characteristics of pressure-transducer kits. The FloTrac sensor kit (Edwards Lifesciences, CA, USA) and the DTXplus transducer kit (Argon Medical Devices) were prepared with planecta ports, and their frequency characteristics were tested with or without ROSE™. ⋯ Planecta ports decrease the natural frequency of the kit. ROSE™ is useful to optimise the frequency characteristics in the kits without or with one planecta port. However, optimisation is difficult with two or more planecta ports, even with the ROSE™ device.
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J Clin Monit Comput · Dec 2015
Photoplethysmography variability as an alternative approach to obtain heart rate variability information in chronic pain patient.
Heart rate variability (HRV) is a well-known method for the assessment of autonomic nervous function of the heart. Previous study suggested that pulse rate variability (PRV) determined by photoplethysmography could be used instead of HRV to more simply assess autonomic nervous function. However, most research studies included healthy subjects. ⋯ This study investigated the correlation coefficient (by Pearson correlation) and agreement (by Bland-Altman analysis) between PRV and HRV in chronic pain patients in the clinical setting. The results showed high significant correlations (p < 0.001, r > 0.86) between all the HRV and PRV parameters and good agreements (ratio < 0.1) between the parameters in terms of HR, mean RR, VLF, LF, nLF, nHF, and SD1/SD2. Our study suggests that HRV can also be reliably estimated using the photoplethysmography-based PP interval in elderly patients with chronic pain.
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J Clin Monit Comput · Dec 2015
Observational StudyCerebral oxygenation and processed EEG response to clamping and shunting during carotid endarterectomy under general anesthesia.
Clamping and shunting during carotid endarterectomy (CEA) surgery causes changes in cerebral blood flow. The purpose of this study was to assess and compare, side by side, the cerebral oxygenation (rSO2) and processed electroencephalogram (EEG) response bilaterally to carotid artery clamping and shunting in patients undergoing CEA under general anesthesia. With institutional approval and written informed consent, patients undergoing CEA under general anesthesia and routine carotid artery shunting were recorded bilaterally, simultaneously and continuously with an rSO2 and processed EEG monitor. ⋯ The rSO2 monitor is more reliable in the real-world clinical setting. Future studies should focus on developing algorithms based on these monitors that can predict clamping-induced cerebral ischemia during CEA in order to decide whether carotid artery shunting is worth the associated risks. From the practical point of view, the rSO2 monitor may be the better monitor for this purpose.