Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2011
Randomized Controlled Trial Comparative StudyA mannequin study of intubation with the AP advance and GlideScope Ranger videolaryngoscopes and the Macintosh laryngoscope.
The AP Advance (APA) is a videolaryngoscope with interchangeable blades: intubators can choose standard Macintosh blades or a difficult-airway blade with increased curvature and a channel to guide the tube to the larynx. The APA may therefore be comparably effective in both normal and difficult airways. We tested the hypotheses that intubation with the APA is no slower than Macintosh laryngoscopy for normal mannequin airways, and that it is no slower than videolaryngoscopy using a GlideScope Ranger in difficult mannequin airways. ⋯ Intubation times were similar with the APA and Macintosh laryngoscopes in mannequins with normal airways. However, intubation with the APA was significantly faster than with the GlideScope in the difficult mannequin simulation.
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Anesthesia and analgesia · Oct 2011
Comparative StudyThe effect of cross-training with adjustable airway model anatomies on laryngoscopy skill transfer.
A problem with learning endotracheal intubation on airway mannequins is poor transfer of direct laryngoscopy skills from model to patient. We developed an airway model with adjustable anatomic features and investigated whether practicing on a model with frequent adjustments improved laryngoscopy skills transfer. ⋯ The results verify that proficiency on one model does not guarantee success on another. However, subjects who trained with a laryngoscopy mannequin in multiple configurations did not show better skill transfer than subjects practicing on fixed configuration airway models.
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Anesthesia and analgesia · Oct 2011
Randomized Controlled Trial Comparative StudyThe impact of phenylephrine, ephedrine, and increased preload on third-generation Vigileo-FloTrac and esophageal doppler cardiac output measurements.
Cardiac output (CO) monitoring based on pulse contour analysis (Vigileo-FloTrac) has the potential to be used for goal-directed fluid therapy in the perioperative setting. However, factors such as vasopressor usage may impact Vigileo-FloTrac's reliability in tracking CO changes. We tested third-generation Vigileo-FloTrac system's ability to accurately measure the changes in CO induced by vasopressor administration and increased preload in comparison with esophageal Doppler measurements. ⋯ The pulse contour method of measuring CO, as implemented in the third-generation Vigileo-FloTrac device, accurately tracks changes in CO when preload changes. However, the pulse contour method does not accurately track changes in CO induced with phenylephrine and ephedrine.
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Anesthesia and analgesia · Oct 2011
Review Historical ArticleArterial waveform analysis for the anesthesiologist: past, present, and future concepts.
Qualitative arterial waveform analysis has been in existence for millennia; quantitative arterial waveform analysis techniques, which can be traced back to Euler's work in the 18th century, have not been widely used by anesthesiologists and other clinicians. This is likely attributable, in part, to the widespread use of the sphygmomanometer, which allows the practitioner to assess arterial blood pressure without having to develop a sense for the higher-order characteristics of the arterial waveform. The 20-year delay in the development of devices that measure these traits is a testament to the primitiveness of our appreciation for this information. ⋯ The area under the peripheral arterial pressure tracing is related to stroke volume when loading conditions are stable; this finding has been used in the development of several continuous cardiac output monitors. Pulse wave velocity may be related to vascular impedance and could potentially improve the accuracy of waveform-based stroke volume estimates. Estimates of central arterial pressures (e.g., aortic) can be produced from peripheral (e.g., brachial, radial) tracings using a Generalized Transfer Function, and are incorporated into the algorithms of several continuous cardiac output monitors.
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Anesthesia and analgesia · Oct 2011
The limitations of near-infrared spectroscopy to assess cerebrovascular reactivity: the role of slow frequency oscillations.
A total hemoglobin reactivity index (THx) derived from near-infrared spectroscopy (NIRS) has recently been introduced to assess cerebrovascular reactivity noninvasively. Analogously to the pressure reactivity index (PRx), THx is calculated as correlation coefficient with arterial blood pressure (ABP). However, the reliability of THx in the injured brain is uncertain. Although slow oscillations have been described in NIRS signals, their significance for assessment of autoregulation remains unclear. In the current study, we investigated the role of slow oscillations of total hemoglobin for NIRS-based cerebrovascular reactivity monitoring. ⋯ Our results suggest that the NIRS-based cerebrovascular reactivity index THx can be used as a noninvasive substitute for PRx, but only during phases with sufficient slow wave power in the input signal. Furthermore, a good agreement between the THx measures on both sides seems to be a prerequisite for comparison of a global (PRx) versus the more local (THx) index. Nevertheless, noninvasive assessment of cerebrovascular reactivity may be desirable in patients without ICP monitoring and help to guide ABP management in these patients.