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Sedation, analgesia and patient observation in interventional radiology
Published in William H. Bush, Karl N. Krecke, Bernard F. King, Michael A. Bettmann, Radiology Life Support (Rad-LS), 2017
Jeffrey E. Quam, Michael A. Bettmann
With regard to clinical use, morphine and meperidine (Demerol®) play an important role as opiate narcotics for longer-term pain control, but have been largely replaced by fentanyl (Sublimaze®) and its congeners, sufentanil (Sufenta®) and alfentanil (Alfenta®), for systemic analgesia during percutaneous interventional procedures. One reason for this transition is the increased lipophilicity of these agents (fentanyl is 7000 times more lipophilic than morphine). This leads to much more rapid penetration into the CNS, more rapid onset of action, and thus more reliable and more reproducible analgesia. Morphine is metabolized in the liver by conjugation with glucuronic acid. One of the products of this metabolism is morphine-6-glucuronide. Compared to morphine, this metabolite is both more potent and has a longer effective half-life. This makes accurate titration for the desired analgesic effect much more difficult without introducing an increased risk of hazardous side-effects. A metabolite of meperidine, nor-meperidine, has been shown to cause tremors and seizures.40 Fentanyl and its congeners have much shorter effective half-lives than morphine or meperidine, and have little significant effect from persisting active metabolites, allowing excellent titration of analgesia. In addition, fentanyl causes less spasm of the sphincter of Oddi and less nausea and vomiting than is commonly observed with morphine. Finally, fentanyl and its congeners cause little if any histamine release, and are thus preferred for patients with known reactive airway disease or hypotension. Only minimal cardiovascular depression is observed with fentanyl, even at high doses. However, it can cause slight bradycardia due to increased vagal tone. An unusual chest-wall rigidity can be seen with rapid injections of high doses of fentanyl. This appears to be due to stimulation of the spinal inspiratory motor neurons, creating a sustained inspiration that may lead to respiratory compromise.41
A comparison of methods used for inducing mental fatigue in performance research: individualised, dual-task and short duration cognitive tests are most effective
Published in Ergonomics, 2020
Kate O’Keeffe, Simon Hodder, Alex Lloyd
Heart rate variability was collected using an Equivital (Hidalgo, UK) life monitor system. The system collected an array of variables including heart rate, breathing rate, and interbeat intervals (IBI). IBI data represent the duration between beats, R-R intervals. Once collected, the data were then analysed using Kubios software (Tarvainen et al. 2014). The extracted IBI data were transferred from excel to a text file where it was then imported to the Kubios HRV standard software. Once imported, the data were passed through a very low artefact correction threshold (Tarvainen et al. 2014). In the time domain, to assess vagal tone, the root mean square of the successive difference (RMSSD) was calculated and has been shown to be highly correlated with parasympathetic activity (Laborde et al. 2017). A second variable extracted was the PNN50 which is also associated with parasympathetic activation and is the percentage of adjacent beats NN intervals that differ from each other by more than 50-ms (Laborde et al. 2017).