Journal of clinical monitoring and computing
-
J Clin Monit Comput · Jun 2019
Outcome impact of hemodynamic and depth of anesthesia monitoring during major cancer surgery: a before-after study.
Hemodynamic and depth of anesthesia (DOA) monitoring are used in many high-risk surgical patients without well-defined indications and objectives. We implemented monitoring guidelines to rationalize hemodynamic and anesthesia management during major cancer surgery. In early 2014, we developed guidelines with specific targets (Mean arterial pressure > 65 mmHg, stroke volume variation < 12%, cardiac index > 2.5 l min-1 m-2, central venous oxygen saturation > 70%, 40 < bispectral index < 60) for open abdominal cancer surgeries > 2 h. ⋯ Intraoperative fluid volumes decreased (16.0 vs. 14.5 ml kg-1 h-1, p = 0.002), whereas the use of inotropes increased (6 vs. 11%, p = 0.022). Postoperative delirium (16 vs. 8%, p = 0.005), urinary tract infections (6 vs. 2%, p = 0.012) and median hospital length of stay (9.6 vs. 8.8 days, p = 0.032) decreased. In patients undergoing major open abdominal surgery for cancer, despite an increase in surgical risk, the implementation of guidelines with predefined targets for hemodynamic and DOA monitoring was associated with a significant improvement in postoperative outcome.
-
J Clin Monit Comput · Jun 2019
Comparative StudyNovel mandibular advancement bite block with supplemental oxygen to both nasal and oral cavity improves oxygenation during esophagogastroduodenoscopy: a bench comparison.
Drug-induced respiratory depression is a major cause of serious adverse events. Adequate oxygenation is very important during sedated esophagogastroduodenoscopy (EGD). Nasal breathing often shifts to oral breathing during open mouth EGD. ⋯ The ratio of nasal to oral breathing played an important role in the FiO2 under hypoventilation but less role under normal ventilation. Bite blocks deliver a higher FiO2 during EGD. The ratio of nasal to oral breathing, supplemental oxygen flow, tidal volume, and respiratory rate influenced the FiO2 in most of the supplemental oxygen devices tested, which are often used for conscious sedation in patients undergoing EGD and colonoscopy.
-
J Clin Monit Comput · Jun 2019
Optimizing target control of the vessel rich group with volatile anesthetics.
The ability to monitor the inspired and expired concentrations of volatile anesthetic gases in real time makes these drugs implicitly targetable. However, the end-tidal concentration only represents the concentration within the brain and the vessel rich group (VRG) at steady state, and very poorly approximates the VRG concentration during common dynamic situations such as initial uptake and emergence. How should the vaporization of anesthetic gases be controlled in order to optimally target VRG concentration in clinical practice? Using a generally accepted pharmacokinetic model of uptake and redistribution, a transfer function from the vaporizer setting to the VRG is established and transformed to the time domain. ⋯ Using a simple and clinically intuitive modification to the targeting algorithm, a variable low-pass boundary layer is applied to the actuation, smoothing discontinuities in the control law and practically eliminating chatter without prolonging the time taken to reach the VRG target concentration by any clinically significant degree. A model is derived for optimum VRG-targeted control of anesthetic vaporizers. An alternate and further application is described, in which deliberate perturbation of the vaporization permits non-invasive estimation of parameters such as cardiac output that are otherwise difficult to measure intra-operatively.