Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2020
Trending algorithm discriminates hemodynamic from injury related TcMEP amplitude loss.
Jasiukaitis and Lyon (J Clin Monit Comput, https://doi.org/10.1007/s10877-018-0181-9, 2018) described an motor evoked potential (MEP)amplitude trending system to detect MEP amplitude loss against a background of MEP variability. They found that the end of case value of a running R2 triggered by a set MEP amplitude loss criterion appeared to discriminate new injury from non-injury in a small sample of three patients. The present study examines the predictive capability of the running R2 in a larger sample of patients (21 injured and 19 non-injured). ⋯ End-of-case R2 values greater than 60% appeared to be highly predictive of new post-operative deficit, while values less than 40% appeared to insure no new deficit. The proposed trending system can discriminate injury from non-injury outcomes when compressive radicular injury during correction for lumbar deformity is involved. This discrimination appears to be successful even when MEP amplitude loss for non-iatrogenic reasons (i.e., hemorrhage) is also occurring.
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J Clin Monit Comput · Feb 2020
Transcranial motor evoked potentials electrically elicited by multi-train stimulation can reflect isolated nerve root injury more precisely than those by conventional multi-pulse stimulation: an experimental study in rats.
Nerve root injury can occur in complex spine surgeries. Recording transcranial motor-evoked potentials (TcMEPs) has been the most popular method to monitor motor function during surgery. However, TcMEPs cannot detect single nerve root injury satisfactorily. ⋯ The change ratio of the amplitude after transection of the nerve root was compared between MTS and conventional single-train stimulation (STS). The change in TcMEP amplitudes for QF after transection of the nerve root at L6 was 97.8 ± 12.2% with MTS and 100.1 ± 7.2% with STS (p = 0.496), whereas that for GC was 40.6 ± 11.5% with MTS and 64.8 ± 8.8% with STS (p < 0.001). MTS could improve the ability to detect isolated nerve root injury in intraoperative TcMEP monitoring.
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J Clin Monit Comput · Feb 2020
Measuring arterial oxygen saturation from an intraosseous photoplethysmographic signal derived from the sternum.
Photoplethysmography performed on the peripheral extremities or the earlobes cannot always provide sufficiently rapid and accurate calculation of arterial oxygen saturation. The purpose of this study was to evaluate a novel photoplethysmography prototype to be fixed over the sternum. Our hypotheses were that arterial oxygen saturation can be determined from an intraosseous photoplethysmography signal from the sternum and that such monitoring detects hypoxemia faster than pulse oximetry at standard sites. ⋯ The sternal probe detected hypoxemia 28.7 s faster than a finger probe (95% CI 20.0-37.4 s, p < 0.001) and 6.6 s faster than an ear probe (95% CI 5.3-8.7 s, p < 0.001). In an experimental setting, arterial oxygen saturation could be determined using the photoplethysmography signal obtained from sternal blood flow after calibration with CO-oximetry. This method detected hypoxemia significantly faster than pulse oximetry performed on the finger or the ear.