Journal of clinical monitoring and computing
-
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.
-
J Clin Monit Comput · Feb 2020
Comparative StudyComparison of the venous-arterial CO2 to arterial-venous O2 content difference ratio with the venous-arterial CO2 gradient for the predictability of adverse outcomes after cardiac surgery.
This study aimed to compare the prognostic performance of the ratio of mixed and central venous-arterial CO2 tension difference to arterial-venous O2 content difference (Pv-aCO2/Ca-vO2 and Pcv-aCO2/Ca-cvO2, respectively) with that of the mixed and central venous-to-arterial carbon dioxide gradient (Pv-aCO2 and Pcv-aCO2, respectively) for adverse events after cardiac surgery. One hundred and ten patients undergoing cardiac surgery with cardiopulmonary bypass were enrolled. After catheter insertion, three blood samples were withdrawn simultaneously through arterial pressure, central venous, and pulmonary artery catheters, before and at the end of the operation, and preoperative and postoperative values were determined. ⋯ However, postoperative Pv-aCO2 was the best predictor of MOMM (area under the curve [AUC]: 0.804; 95% confidence interval [CI] 0.688-0.921), at a 5.1-mmHg cut-off, sensitivity was 76.0%, and specificity was 74.1%. Multivariate analysis revealed that postoperative Pv-aCO2 was an independent predictor of MOMM (odds ratio [OR]: 1.42, 95% CI 1.01-2.00, p = 0.046) and prolonged ICU stay (OR: 1.45, 95% CI 1.05-2.01, p = 0.024). Pv-aCO2 at the end of cardiac surgery was a better predictor of postoperative complications than Pv-aCO2/Ca-vO2 and Pcv-aCO2/Ca-cvO2.
-
J Clin Monit Comput · Feb 2020
Observational StudyA simplified quantitative acid-base approach for patients with acute respiratory diseases.
The Stewart-Figge acid-base model has been criticized for being mathematically complex. We aimed to develop simpler formalisms, which can be used at the bedside. The following simplifications were used: (1) [Ca2+] and [Mg2+] are replaced by their mid-reference concentrations (2) pH is set to 7.4. ⋯ A [SIDa, adj] < 50.4 meq/l had an accuracy of 0.995 (p < 0.001) for the diagnosis of strong ion (SI) acidosis, while a [SIDa, adj] > 52.5 meq/l had an accuracy of 0.997 (p < 0.001) for the diagnosis of SI alkalosis. A [BICgap] > 11.6 meq/l predicted unmeasured ion (UI) acidosis with an accuracy of 0.997 (p < 0.001), while an [AGc] > 19.88 meq/l predicted UI acidosis with an accuracy of 0.994 (p < 0.001). The "[BICgap] model" is a reliable tool for the assessment of acid-base disorders in patients with acute respiratory diseases. [BICgap] is not inferior to [AGc] in the diagnosis of UI acidosis.
-
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.