Journal of clinical monitoring and computing
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J Clin Monit Comput · Oct 2023
Effects of infusion tubing line lengths and syringe sizes on infusion system compliance: an experimental study using a syringe-type infusion pump at low flow rate.
Ideally, the flow delivery of an infusion system is proportional only to the rate of mechanical actuation of the syringe pump plunger. However, in the real world, overall infusion system compliance may be affected by components such as an extension of tubing lines, or different sizes of syringes. With higher compliance, there may be greater chances of flow irregularity. ⋯ In the occlusion alarm experiment, the occlusion alarm could be delayed by 69.76 ± 3.98 min for the 50-ml syringe with a 560 cm infusion line set-up. In conclusion, the compliance of a syringe pump system increases as the loaded syringe size, or the length of the infusion tubing increases. The occlusion alarm may be much delayed and not useful in highly compliant systems with respect to the potential occlusion of the infusion system, so more attention is required when using a highly compliant infusion system.
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J Clin Monit Comput · Oct 2023
Observational StudyEffects of ephedrine and phenylephrine on cerebral oxygenation: observational prospective study using near-infrared time-resolved spectroscopy.
It has been reported that cerebral oxygenation (ScO2) measured by near infrared spectroscopy is maintained or increased by treatment with ephedrine, whereas almost all previous reports demonstrated that phenylephrine reduced ScO2. As the mechanism of the latter, the interference of the extracranial blood flow, that is extracranial contamination, has been suspected. Accordingly, in this prospective observational study, we utilized time-resolved spectroscopy (TRS), in which the effect of extracranial contamination is thought to be minimal, and evaluated whether the same result was obtained. ⋯ The mean differences of tHb were less than 0.02 μM and the predicted mean differences were less than 0.2 μM for the drugs. The changes in ScO2 and tHb after treatments with ephedrine and phenylephrine were very small and clinically insignificant when measured by TRS. Previous reports about phenylephrine may have been affected by extracranial contamination.
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J Clin Monit Comput · Oct 2023
Observational StudyEvaluation of the accuracy of oscillometric non-invasive blood pressure measurement at the ankle in children during general anesthesia.
This study aimed to evaluate the accuracy of oscillometric blood pressure measurement at the ankle in children using invasive blood pressure as reference standard. This prospective observational study included children undergoing noncardiac surgery. Paired radial invasive and ankle non-invasive blood pressure measurements were obtained. ⋯ The concordance rate of ankle blood pressure was 72%, 71%, and 77% for delta SBP, DBP and MAP, respectively. The AUC (95% confidence interval) for ankle MAP ability to detect hypotension was 0.91 (0.89-0.93) with negative predictive value of 100% at cut-off value ≤ 70 mmHg, We concluded that in pediatric population undergoing noncardiac surgery, ankle blood pressure was not interchangeable with the corresponding invasive readings with the ankle MAP having the least bias compared to SBP and DBP. An ankle MAP > 70 mmHg can exclude hypotension with negative predictive value of 100%.
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J Clin Monit Comput · Oct 2023
Single-FiO2 lung modelling with machine learning: a computer simulation incorporating volumetric capnography.
We investigated whether machine learning (ML) analysis of ICU monitoring data incorporating volumetric capnography measurements of mean alveolar PCO2 can partition venous admixture (VenAd) into its shunt and low V/Q components without manipulating the inspired oxygen fraction (FiO2). From a 21-compartment ventilation / perfusion (V/Q) model of pulmonary blood flow we generated blood gas and mean alveolar PCO2 data in simulated scenarios with shunt values from 7.3% to 36.5% and a range of FiO2 settings, indirect calorimetry and cardiac output measurements and acid- base and hemoglobin oxygen affinity conditions. A 'deep learning' ML application, trained and validated solely on single FiO2 bedside monitoring data from 14,736 scenarios, then recovered shunt values in 500 test scenarios with true shunt values 'held back'. ⋯ With corresponding VenAd values calculated from the same bedside data, low V/Q flow can be reported as VenAd-shunt. ML analysis of blood gas, indirect calorimetry, volumetric capnography and cardiac output measurements can quantify pulmonary oxygenation deficits as percentage shunt flow (V/Q = 0) versus percentage low V/Q flow (V/Q > 0). High fidelity reports are possible from analysis of data collected solely at the operating FiO2.
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J Clin Monit Comput · Oct 2023
Clinical validation of an adapted Eleveld Model for high-dose propofol treatments for depression.
Repeated administration of high doses of propofol to patients with treatment-resistant depression (TRD) has been shown to produce antidepressant effects in small clinical trials. These effects can be elicited when the patient's EEG burst-suppression ratio (BSR) is maintained at 70-90% for 15 min in repeated treatments. This deep anesthesia domain lies beyond the range of current propofol pharmacokinetic/pharmacodynamic (PK/PD) models. ⋯ Median absolute performance error (MdAPE) between the estimated and observed BSR (25th-75th percentile) was 6.63 (3.79-12.96) % points and 8.51 (4.32-16.74) % between the estimated and observed treatment duration. This predictive performance is statistically significantly better at predicting BSR compared with the standard Eleveld model at deep anesthesia levels. Our adapted Eleveld model provides a useful tool to aid dosing propofol for high-dose anesthetic treatments for depression.