Journal of clinical monitoring and computing
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J Clin Monit Comput · Jun 2019
A motor evoked potential trending system may discriminate outcome: retrospective application with three cases.
This report presents a method for tracking Motor Evoked Potential (MEP) amplitudes over the course of a case using a moving least squares linear regression (LSMAs). During a case, newly obtained MEP amplitudes are compared to those predicted by a just previous linear regression (least squares moving average or LSMA). When detected by this comparison, a set criterion amplitude loss will then trigger linear regression of ensuing MEP amplitudes on an expanding step function which tracks the persistence of the amplitude loss for the remainder of the case. ⋯ In the third case the tracking method again successfully triggered a predictive R-Square despite the limited number of pre-event trials. The R-Square value of the expanding step function regression appears to have discriminative capability with regard to new post-op deficit. Given the importance of the intra-operative MEP for monitoring motor functioning and the high degree of variability that can affect it, the development of new quantitative, statistical methods to detect real from apparent MEP change will be necessary.
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J Clin Monit Comput · Jun 2019
Comparative StudyNovel mandibular advancement bite block with supplemental oxygen to both nasal and oral cavity improves oxygenation during esophagogastroduodenoscopy: a bench comparison.
Drug-induced respiratory depression is a major cause of serious adverse events. Adequate oxygenation is very important during sedated esophagogastroduodenoscopy (EGD). Nasal breathing often shifts to oral breathing during open mouth EGD. ⋯ The ratio of nasal to oral breathing played an important role in the FiO2 under hypoventilation but less role under normal ventilation. Bite blocks deliver a higher FiO2 during EGD. The ratio of nasal to oral breathing, supplemental oxygen flow, tidal volume, and respiratory rate influenced the FiO2 in most of the supplemental oxygen devices tested, which are often used for conscious sedation in patients undergoing EGD and colonoscopy.
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J Clin Monit Comput · Jun 2019
Optimizing target control of the vessel rich group with volatile anesthetics.
The ability to monitor the inspired and expired concentrations of volatile anesthetic gases in real time makes these drugs implicitly targetable. However, the end-tidal concentration only represents the concentration within the brain and the vessel rich group (VRG) at steady state, and very poorly approximates the VRG concentration during common dynamic situations such as initial uptake and emergence. How should the vaporization of anesthetic gases be controlled in order to optimally target VRG concentration in clinical practice? Using a generally accepted pharmacokinetic model of uptake and redistribution, a transfer function from the vaporizer setting to the VRG is established and transformed to the time domain. ⋯ Using a simple and clinically intuitive modification to the targeting algorithm, a variable low-pass boundary layer is applied to the actuation, smoothing discontinuities in the control law and practically eliminating chatter without prolonging the time taken to reach the VRG target concentration by any clinically significant degree. A model is derived for optimum VRG-targeted control of anesthetic vaporizers. An alternate and further application is described, in which deliberate perturbation of the vaporization permits non-invasive estimation of parameters such as cardiac output that are otherwise difficult to measure intra-operatively.
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J Clin Monit Comput · Jun 2019
Objectively measured early physical activity after total hip or knee arthroplasty.
Although reduced early physical function after total hip- and knee arthroplasty (THA/TKA) is well-described, the underlying reasons have not been clarified with detailed studies on pathophysiological mechanisms related to recovery, thereby prohibiting advances in rehabilitation. Thus, we aimed to describe early post-THA/TKA physical activity measured by actigraphy and potential underlying pathophysiological mechanisms related to recovery in a well-defined cohort of THA and TKA patients. Daytime-activity was measured from 2 days before until 13 (THA) or 20 (TKA) days after surgery. ⋯ Physical activity was reduced the first weeks following THA/TKA, but with large inter-individual variations in recovery profiles. No single pathogenic factor was associated with a poor recovery. Early risk stratified interventions are needed in patients on a suboptimal course.
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J Clin Monit Comput · Jun 2019
The importance of sensor contacting force for predicting fluid responsiveness in children using respiratory variations in pulse oximetry plethysmographic waveform.
Predicting fluid responsiveness is crucial for adequate fluid management. Respiratory variations in pulse oximetry plethysmographic waveform amplitude (ΔPOP) are used to predict fluid responsiveness, but show inconsistent results when used for children. Contacting force between the measurement site and sensor can affect the ΔPOP value, thereby hindering its reliability as an indicator. ⋯ A significant difference between the responders and non-responders was found only in ΔPOPs at 0.9-1.2N contacting force (P = 0.002) and individually adjusted contacting force (P < 0.000), while other contacting force groups did not show significant differences. ΔVpeak predicted a 15% increase in SVI (P = 0.008), whereas PPV did not. The ability of ΔPOP to predict fluid responsiveness depends on the contacting force in mechanically ventilated children. When contacting force is controlled to an adequate degree, the ability of ΔPOP to predict fluid responsiveness can be improved.