Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2014
Lessons learned from closed loops in engineering: towards a multivariable approach regulating depth of anaesthesia.
In this paper is presented a brief state of art regarding the multivariable formulation for controlling the depth of anaesthesia by means of two intravenously administrated drugs, i.e. propofol and remifentanil. In a feasibility study of determining a suitable variable to quantify analgesia levels in patients undergoing cardiac surgery, the bispectral index and an electromyogram-based surrogate variable are proposed as the controlled variables. The study is carried on in the context of implementing a multivariable predictive control algorithm. The simulation results show that such a paradigm is feasible, although it does not guarantee perfect knowledge of the analgesia level-in other words, the variable is not validated against typical evaluations of the pain levels (e.g. clinical scores).
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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
Melodic algorithms for pulse oximetry to allow audible discrimination of abnormal systolic blood pressures.
An anesthesiologist must remain vigilant of the patient's clinical status, incorporating many independent physiological measurements. Oxygen saturation and heart rate are represented by continuous audible tones generated by the pulse oximeter, a mandated monitoring device. Other important clinical parameters--notably blood pressure--lack any audible representation beyond arbitrarily-configured threshold alarms. ⋯ A rhythmic variation in which additional auditory information was conveyed only at halftime intervals, with every other "beat" of the pulse oximeter, was strongly favored. The respondents also strongly favored the use of musical chords over single tones. Given three algorithms of tones embedded in the pulse oximeter signal, anesthesiologists preferred a melodic tone to signal a significant change in blood pressure.
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J Clin Monit Comput · Dec 2014
Clinical TrialNon-invasive cardiac output evaluation in postoperative cardiac surgery patients, using a new prolonged expiration-based technique.
The gold standard methods to measure cardiac output (CO) are invasive and expose the patient to high risks of various complications. The aim of this study is to assess an innovative non-invasive method for CO monitoring in mechanically ventilated patients after cardiac surgery and its agreement with values obtained by thermodilution technique. Continuous monitoring of respiratory gas concentrations and airflow allows the estimation of CO through a newly developed algorithm derived from a modified version of the Fick equation. ⋯ COK shows a mean percentage error of 34 %. In stable mechanically ventilated patients, undergone cardiac surgery, the proposed method is reliable if compared to the thermodilution. Considering the non-invasivity of the technique, further evaluations of its performances are encouraged.