Anesthesia and analgesia
-
Anesthesia and analgesia · Dec 2014
The Accuracy of a Near-Infrared Spectroscopy Cerebral Oximetry Device and Its Potential Value for Estimating Jugular Venous Oxygen Saturation.
An intriguing potential clinical use of cerebral oximeter measurements (SctO2) is the ability to noninvasively estimate jugular bulb venous oxygen saturation (SjvO2). Our purpose in this study was to determine the accuracy of the FORE-SIGHT(®) (CAS Medical Systems, Branford, CT), which is calibrated to a weighted average of 70% (SjvO2) and 30% arterial saturation, for Food and Drug Administration pre-market approval 510(k) certification by adapting an industry standard protocol, ISO 9919:2005 (www.ISO.org) (used for pulse oximeters), and to evaluate the use of SctO2 and SpO2 measurements to noninvasively estimate jugular venous oxygen saturation (SnvO2). ⋯ The FORE-SIGHT cerebral oximeter was able to estimate oxygen saturation within the tissues of the frontal lobe under conditions of normocapnia and varying degrees of hypoxia (with 95% confidence interval of [-5.60 to 5.78] with ipsilateral blood sample data). These findings from healthy volunteers also suggest that the use of the calculated SnvO2 derived from SctO2 and SpO2 values may be a reasonable noninvasive method of estimating SjvO2 and therefore global cerebral oxygen consumption in the clinical setting. Further laboratory and clinical research is required to define the clinical utility of near-infrared spectroscopy determination of SctO2 and SnvO2 in the operating room setting.
-
Anesthesia and analgesia · Dec 2014
ReviewPrevention of peri-induction hypertension in preeclamptic patients: a focused review.
Many medications have been used to prevent the hypertensive response to the induction of general anesthesia and laryngoscopy in preeclamptic patients, with varying results. In this focused review, we summarize the available data and pharmacologic profiles of these drugs. Several different drug classes may be used safely; however, magnesium bolus, lidocaine, calcium channel antagonists other than nicardipine, and hydralazine are not recommended. Further research is warranted into the hemodynamic impact of varying the induction drug dose or combining different classes of drugs.
-
Anesthesia and analgesia · Dec 2014
ReviewA review of signal processing used in the implementation of the pulse oximetry photoplethysmographic fluid responsiveness parameter.
ΔPOP is a physiological parameter derived from the respiration-induced change in the pulse oximetry plethysmographic (POP) waveform or "pleth." It has been proposed as a proxy for pulse pressure variation used in the determination of the response to intravascular volume expansion in hypovolemic patients. Many studies have now reported on the parameter, and many research groups have constructed algorithms for its computation from the first principles where the implementation details have been described. This review focuses on the signal processing aspects of ΔPOP, as reported in the literature, and aims to provide a comprehensive summary of the wide-ranging algorithmic strategies that have been attempted in its computation. ⋯ This is followed by an overview of the signal processing methods used in the reported studies, including details of exclusion criteria, manual filtering (preprocessing), gain change issues, acquisition details, selection of registration periods, averaging methods, physiological influences on the pleth, and comments by the investigators themselves. It is concluded that to develop a robust, fully automated ΔPOP algorithm for use in the clinical environment, more rigorous signal processing is required. Specifically, signals should be evaluated over significant periods of time, with emphasis on the quality and temporal relevance of the information.