Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2014
Individualizing propofol dosage: a multivariate linear model approach.
In the last decades propofol became established as an intravenous agent for the induction and maintenance of both sedation and general anesthesia procedures. In order to achieve the desired clinical effects appropriate infusion rate strategies must be designed. Moreover, it is important to avoid or minimize associated side effects namely adverse cardiorespiratory effects and delayed recovery. ⋯ The results obtained in the test set comprising a broad range of characteristics are satisfactory since the models are able to predict bolus, infusion rates and the effect-site concentrations comparable to those of TCI. Furthermore, comparisons of the effect-site concentrations for dosages predicted by the proposed Linear model and the Marsh model for the same target concentration is achieved using Schnider model and a factorial design on the factors (patients characteristics). The results indicate that the Linear model predicts a dosage profile that is faster in leading to an effect-site concentration closer to the desired target concentration.
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J Clin Monit Comput · Dec 2014
Clinical TrialDetection of respiratory compromise by acoustic monitoring, capnography, and brain function monitoring during monitored anesthesia care.
Episodes of apnea in sedated patients represent a risk of respiratory compromise. We hypothesized that acoustic monitoring would be equivalent to capnography for detection of respiratory pauses, with fewer false alarms. In addition, we hypothesized that the patient state index (PSI) would be correlated with the frequency of respiratory pauses and therefore could provide information about the risk of apnea during sedation. ⋯ For the 51 respiratory pauses validated by retrospective analysis, the sensitivity, specificity, and likelihood ratio positive for detection were 16, 96 %, and 3.5 for clinician observation; 88, 7 %, and 1.0 for capnography; and 55, 87 %, and 4.1 for acoustic monitoring. There was no correlation between PSI and respiratory pause events. Acoustic monitoring had the highest likelihood ratio positive for detection of respiratory pause events compared with capnography and clinician observation and, therefore, may provide the best method for respiration rate monitoring during these procedures.
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J Clin Monit Comput · Dec 2014
Randomized Controlled TrialForty-five degree wrist angulation is optimal for ultrasound guided long axis radial artery cannulation in patients over 60 years old: a randomized study.
Arterial cannulation is a common anaesthetic procedure that might be challenging and time-consuming in elderly patients. To establish an appropriate wrist joint position for arterial cannulation is crucial for ultrasound (US)-guided cannulation success. This study aimed to find out the optimal wrist joint angle for long axis in-plane (LA-IP) US-guided approach in radial artery cannulation in elderly patients. ⋯ Number of attempts and total success rate were similar among groups, whereas first attempt success rate was significantly increased in 45° group compared to other groups (p < 0.05). Mean arterial height of the first attempt successful group was statistically increased compared to the first attempt failed group (p < 0.001) and mean cannulation time and mean number of attempts were also negatively correlated with arterial height (p < 0.001; for all comparisons). The 45° wrist angle increment might be advantageous in US-guided LA-IP radial artery cannulation in elderly patients in view of cannulation time and first attempt success rate.
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J Clin Monit Comput · Dec 2014
Measuring gas exchange with step changes in inspired oxygen: an analysis of the assumption of oxygen steady state in patients suffering from COPD.
Bedside estimation of pulmonary gas exchange efficiency may be possible from step changes in FIO2 and subsequent measurement of arterial oxygenation at steady state conditions. However, a steady state may not be achieved quickly after a change in FIO2, especially in patients with lung disease such as COPD, rendering this approach cumbersome. This paper investigates whether breath by breath measurement of respiratory gas and arterial oxygen levels as FIO2 is changed can be used as a much more rapid alternative to collecting data from steady state conditions for measuring pulmonary gas exchange efficiency. ⋯ Calculated model parameters were shown to be similar for the two data sets, with Bland-Altman bias and limits of agreement of -0.4 and -3.0 to 2.2 % for calculation of pulmonary shunt and 0.17 and -0.47 to 0.81 kPa for alveolar to end-capillary PO2, a measure of oxygen abnormality due to shunting plus regions of low [Formula: see text] A/[Formula: see text] ratio. This study shows that steady state oxygen levels may not be necessary when estimating pulmonary gas exchange using changes in FIO2. As such this technique may be applicable in patients with lung disease such as COPD.
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J Clin Monit Comput · Dec 2014
Randomized Controlled TrialNon-stationarity of EEG during wakefulness and anaesthesia: advantages of EEG permutation entropy monitoring.
Monitors evaluating the electroencephalogram (EEG) to determine depth of anaesthesia use spectral analysis approaches for analysis windows up to 61.5 s as well as additional smoothing algorithms. Stationary EEG is required to reliably apply the index algorithms. Because of rapid physiological changes, artefacts, etc., the EEG may not always fulfil this requirement. ⋯ Especially during wakefulness a conflict between stationary EEG sequence durations and methods used for monitoring may exist. PeEn does not require stationarity and functions for EEG sequences as short as 2 s. These promising results seem to support the application of non-linear parameters, such as PeEn, to depth of anaesthesia monitoring.