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An observational study on patient admission in the anaesthesia gas monitor and minimum alveolar concentration monitoring: A deficiency with huge impact.

ABSTRACT: Minimum alveolar concentration (MAC) monitoring is an integral part of modern-day anaesthesia. Both MAC and MAC-awake are age dependant, and age of the patient needs to be entered in the monitor. This study was aimed to assess the practice of patient birth year entry in the anaesthesia monitor and its impact on MAC monitoring.Sixty volatile anaesthetic-based general anaesthetics (GAs) were observed silently in two tertiary care teaching hospitals with regard to 'birth year' entry in the patient monitor. The impact on MAC for non-entry of age was assessed. The observed MAC reading and the MAC corrected for age (MACage) of the patients were noted. Paired t-test was used to compare the differences in observed MAC and MACage values. P <0.05 was significant.Sixty GAs of patients aged between 10 and 68 years were observed; 96.67% anaesthetics were conducted without entering 'birth year'. Thirty-four patients (mean age 35.14 ± 15.38 years) were further assessed for impact of non-entry of age. The observed MAC was similar to MACage in patients aged 40 ± 5 years (36-45 years group). Nearly 79.41% of the observed MACs were incorrect; 55.88% patients were potentially underdosed whereas 23.53% were overdosed.Omitting patient age entry in the monitor results in erroneous MAC values, exposing patients <40 years to underdosing and older patients to overdose.

SUBMITTER: Karim HMR

PROVIDER: S-EPMC5530742 | biostudies-other | 2017 Jul

REPOSITORIES: biostudies-other

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Project description:BackgroundSleep disorders are commonly encountered in clinic. Evidences showed that sleep deprivation may modulate the effectiveness of general anesthetics in rats. However, this phenomenon has not been explored in humans. The study aimed to investigate whether the hypnotic potency of sevoflurane in patients with sleep disorders differ from patients with normal sleep habits.MethodsWe recruited 44 patients scheduled for elective breast surgery and eventually analyzed 38 patients, including 19 subjects with normal sleep habits and 19 subjects with sleep disorders. According to the Dixon 'up-and-down' design, patients received sevoflurane at preselected concentrations starting at 1.0?vol%. After a steady-state period, a verbal command for testing awakening was performed. Based on the negative or positive response to the verbal command, we decreased or increased the concentration of sevoflurane by 0.2?vol% in the next patient accordingly. Plasma orexin-A was also measured before observation.ResultsThe MACawake of sevoflurane was 0.80% [95% confidence interval (CI), 0.683-0.926%] in the sleep disordered group vs 0.60% [95% CI, 0.493-0.689%] in the control group. The relative median potency between groups was 0.750 (95% CI, 0.236-0.969). Patients with sleep disorders had significantly higher orexin-A levels than control (72.17?±?18.24 vs. 36.16?±?14.18?pg/mL). A significant, positive relationship was detected between orexin-A level and probability of awakening (OR?=?1.081, 95% CI is 1.020-1.146, P?=?0.008).ConclusionsMACawake of sevoflurane is higher in mild-aged women of breast surgery with sleep disorders compared to those with normal sleep habits. The increased anesthetic requirement may be related to changes of orexin-A levels. These findings suggest that sleep may have a potential impact on clinical anesthesia, including changes of sensitivity to anesthetics or postoperative complications. Further research is needed to confirm this hypothesis.Clinical trial registrationChinese Clinical Trial Registry (ChiCTR1800016022), date of registration 07 May 2018.

Project description:The incidence of intraoperative awareness with explicit recall is 1-2/1000 cases in the United States. The Bispectral Index monitor is an electroencephalographic method of assessing anesthetic depth that has been shown in one prospective study to reduce the incidence of awareness in the high-risk population. In the B-Aware trial, the number needed to treat in order to prevent one case of awareness in the high-risk population was 138. Since the number needed to treat and the associated cost of treatment would be much higher in the general population, the efficacy of the Bispectral Index monitor in preventing awareness in all anesthetized patients needs to be clearly established. This is especially true given the findings of the B-Unaware trial, which demonstrated no significant difference between protocols based on the Bispectral Index monitor or minimum alveolar concentration for the reduction of awareness in high risk patients.To evaluate efficacy in the general population, we are conducting a prospective, randomized, controlled trial comparing the Bispectral Index monitor to a non-electroencephalographic gauge of anesthetic depth. The total recruitment for the study is targeted for 30,000 patients at both low and high risk for awareness. We have developed a novel algorithm that is capable of real-time analysis of our electronic perioperative information system. In one arm of the study, anesthesia providers will receive an electronic page if the Bispectral Index value is >60. In the other arm of the study, anesthesia providers will receive a page if the age-adjusted minimum alveolar concentration is <0.5. Our minimum alveolar concentration algorithm is sensitive to both inhalational anesthetics and intravenous sedative-hypnotic agents.Awareness during general anesthesia is a persistent problem and the role of the Bispectral Index monitor in its prevention is still unclear. The Michigan Awareness Control Study is the largest prospective trial of awareness prevention ever conducted.Clinical Trial NCT00689091.

Project description:BackgroundIntensive care unit (ICU) physicians have extended the minimum alveolar concentration (MAC) to deliver and monitor long-term volatile sedation in critically ill patients. There is limited evidence of MAC's reliability in controlling sedation depth in this setting. We hypothesized that sedation depth, measured by the electroencephalography (EEG)-derived Narcotrend-Index (burst-suppression N_Index 0-awake N_Index 100), might drift downward over time despite constant MAC values.MethodsThis prospective single-centre randomized clinical study was conducted at a University Hospital Surgical Intensive Care Unit and included consecutive, postoperative ICU patients fulfilling the inclusion criteria. Patients were randomly assigned to receive uninterrupted inhalational sedation with isoflurane, sevoflurane, or desflurane. The end-expiratory concentration of the anaesthetics and the EEG-derived index were measured continuously in time-stamped pairs. Sedation depth was also monitored using Richmond-Agitation-Sedation-Scale (RASS). The paired t-test and linear models (bootstrapped or multilevel) have been employed to analyze MAC, N_Index and RASS across the three groups.ResultsThirty patients were recruited (female/male: 10/20, age 64 ± 11, Simplified Acute Physiology Score II 30 ± 10). In the first 24 h, 21.208 pairs of data points (N_Index and MAC) were recorded. The median MAC of 0.58 ± 0.06 remained stable over the sedation time in all three groups. The t-test indicated in the isoflurane and sevoflurane groups a significant drop in RASS and EEG-derived N_Index in the first versus last two sedation hours. We applied a multilevel linear model on the entire longitudinal data, nested per patient, which produced the formula N_Index = 43 - 0.7·h (R2 = 0.76), showing a strong negative correlation between sedation's duration and the N_Index. Bootstrapped linear models applied for each sedation group produced: N_Index of 43-0.9, 45-0.8, and 43-0.4·h for isoflurane, sevoflurane, and desflurane, respectively. The regression coefficient for desflurane was almost half of those for isoflurane and sevoflurane, indicating a less pronounced time-effect in this group.ConclusionsMaintaining constant MAC does not guarantee stable sedation depth. Thus, the patients necessitate frequent clinical assessments or, when unfeasible, continuous EEG monitoring. The differences across different volatile anaesthetics regarding their time-dependent negative drift requires further exploration.Trial registrationNCT03860129.

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An observational study on patient admission in the anaesthesia gas monitor and minimum alveolar concentration monitoring: A deficiency with huge impact.

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