30 de setembro de 2013

Artigo recomendado: The Anesthesia in Abdominal Aortic Surgery (ABSENT) Study

A Prospective, Randomized, Controlled Trial Comparing Troponin T Release with Fentanyl–Sevoflurane and Propofol–Remifentanil Anesthesia in Major Vascular Surgery

Espen E. Lindholm, Erlend Aune, Camilla B. Norén, Ingebjørg Seljeflot, Thomas Hayes, Jan E. Otterstad, Knut A. Kirkeboen

Background: On the basis of data indicating that volatile anesthetics induce cardioprotection in cardiac surgery, current guidelines recommend volatile anesthetics for maintenance of general anesthesia during noncardiac surgery in hemodynamic stable patients at risk for perioperative myocardial ischemia. The aim of the current study was to compare increased troponin T (TnT) values in patients receiving sevoflurane-based anesthesia or total intravenous anesthesia in elective abdominal aortic surgery.

Methods: A prospective, randomized, open, parallel-group trial comparing sevoflurane-based anesthesia (group S) and total intravenous anesthesia (group T) with regard to cardioprotection in 193 patients scheduled for elective abdominal aortic surgery. Increased TnT level on the first postoperative day was the primary endpoint. Secondary endpoints were postoperative complications, nonfatal coronary events and mortality.

Results: On the first postoperative day increased TnT values (>13 ng/l) were found in 43 (44%) patients in group S versus 41 (43%) in group T (P = 0.999), with no significant differences in TnT levels between the groups at any time point. Although underpowered, the authors found no differences in postoperative complications, nonfatal coronary events or mortality between the groups.

Conclusions: In elective abdominal aortic surgery sevoflurane- based anesthesia did not reduce myocardial injury, evaluated by TnT release, compared with total intravenous anesthesia. These data indicate that potential cardioprotective effects of volatile anesthetics found in cardiac surgery are less obvious in major vascular surgery.

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27 de setembro de 2013

Artigo recomendado: Perioperative Auto-titrated Continuous Positive Airway Pressure Treatment in Surgical Patients with Obstructive Sleep Apnea

A Randomized Controlled Trial

Pu L iao, Quanwei L uo, isham E lsaid, Weimin Kang, Colin M. Shapiro, Frances Chung

Anesthesiology 2013; 119:837-47, Liao et al.


Background: Obstructive sleep apnea (OSA) may worsen postoperatively. The objective of this randomized open-label trial is to determine whether perioperative auto-titrated continuous positive airway pressure (APAP) treatment decreases postoperative apnea hypopnea index (AHI) and improves oxygenation in patients with moderate and severe OSA.

Methods: The consented patients with AHI of more than 15 events/h on preoperative polysomnography were randomized into the APAP or control group (receiving routine care). The APAP patients received APAP for 2 or 3 preoperative, and 5 postoperative nights. All patients were monitored with oximetry for 7 to 8 nights (N) and underwent polysomnography on postoperative N3. The primary outcome was AHI on the postoperative N3.

Results: One hundred seventy-seven OSA patients undergoing orthopedic and other surgeries were enrolled (APAP: 87 and control: 90). There was no difference between the two groups in baseline data. One hundred six patients (APAP: 40 and control: 66) did polysomnography on postoperative N3, and 100 patients (APAP: 39 and control: 61) completed the study. The compliance rate of APAP was 45%. The APAP usage was 2.4–4.6 h/night. In the APAP group, AHI decreased from preoperative baseline: 30.1 (22.1, 42.5) events/h (median [25th, 75th percentile]) to 3.0 (1.0, 12.5) events/h on postoperative N3 (P < 0.001), whereas, in the control group, AHI increased from 30.4 (23.2, 41.9) events/h to 31.9 (13.5, 50.2) events/h, P = 0.302. No significant change occurred in the central apnea index.

Conclusions: The trial showed the feasibility of perioperative APAP for OSA patients. Perioperative APAP treatment significantly reduced postoperative AHI and improved oxygen saturation in the patients with moderate and severe OSA.

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24 de setembro de 2013

Artigo recomendado: Risk Stratification Tools for Predicting Morbidity and Mortality in Adult Patients Undergoing Major Surgery

Qualitative Systematic Review

Suneetha Ramani Moonesinghe, Michael G. Mythen, Priya Das, Kathryn M. Rowan, Michael P. W. Grocott

Anesthesiology 2013; 119:959-81, Moonesinghe et al.

Risk stratification is essential for both clinical risk prediction and comparative audit. There are a variety of risk stratification tools available for use in major noncardiac surgery, but their discrimination and calibration have not previously been systematically reviewed in heterogeneous patient cohorts.

Embase, MEDLINE, and Web of Science were searched for studies published between January 1, 1980 and August 6, 2011 in adult patients undergoing major noncardiac, nonneurological surgery. Twenty-seven studies evaluating 34 risk stratification tools were identified which met inclusion criteria. The Portsmouth-Physiology and Operative Severity Score for the enUmeration of Mortality and the Surgical Risk Scale were demonstrated to be the most consistently accurate tools that have been validated in multiple studies; however, both have limitations. Future work should focus on further evaluation of these and other parsimonious risk predictors, including validation in international cohorts. There is also a need for studies examining the impact that the use of these tools has on clinical decision making and patient outcome.

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20 de setembro de 2013

Artigo recomendado: Relationship between Intraoperative Mean Arterial Pressure and Clinical Outcomes after Noncardiac Surgery

Toward an Empirical Definition of Hypotension

Michael Walsh, Philip J. Devereaux, Amit X. G arg, Andrea Kurz, Alparslan Turan, Reitze N. Rodseth, Jacek Cywinski, Lehana Thabane, Daniel I . S essler

Anesthesiology 2013; 119:507-15

Background: Intraoperative hypotension may contribute to postoperative acute kidney injury (AKI) and myocardial injury, but what blood pressures are unsafe is unclear. The authors evaluated the association between the intraoperativemean arterial pressure (MAP) and the risk of AKI and myocardial injury.

Methods: The authors obtained perioperative data for 33,330 noncardiac surgeries at the Cleveland Clinic, Ohio. The authors evaluated the association between intraoperative MAP from less than 55 to 75 mmHg and postoperative AKI and myocardial injury to determine the threshold of MAP where risk is increased. The authors then evaluated the association between the duration below this threshold and their outcomes adjusting for potential confounding variables.

Results: AKI and myocardial injury developed in 2,478 (7.4%) and 770 (2.3%) surgeries, respectively. The MAP threshold where the risk for both outcomes increased was less than 55 mmHg. Compared with never developing a MAP less than 55 mmHg, those with a MAP less than 55 mmHg for 1–5, 6–10, 11–20, and more than 20 min had graded increases in their risk of the two outcomes (AKI: 1.18 [95% CI, 1.06–1.31], 1.19 [1.03–1.39], 1.32 [1.11–1.56], and 1.51 [1.24–1.84], respectively; myocardial injury 1.30 [1.06–1.5], 1.47 [1.13–1.93], 1.79 [1.33–2.39], and 1.82 [1.31–2.55], respectively].

Conclusions: Even short durations of an intraoperative MAP less than 55 mmHg are associated with AKI and myocardial injury. Randomized trials are required to determine whether outcomes improve with interventions that maintain an intraoperative MAP of at least 55 mmHg.

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17 de setembro de 2013

Artigo recomendado: Oxytocin Pretreatment Attenuates Oxytocin-induced Contractions in Human Myometrium In Vitro

Mrinalini Balki, Magda Erik-Soussi, John Kingdom, Jose C. A. Carvalho

Anesthesiology 2013; 119:552-61; Balki et al.


Background: Oxytocin receptor desensitization has been shown to occur in humans at biomolecular level and in isolated rat myometrium; however, its effect on human myometrial contractility has not been demonstrated. The objective of this in vitro study was to investigate the contractile response of human pregnant myometrium to oxytocin after pretreatment with different concentrations of oxytocin for variable durations.

Methods: Myometrial samples were obtained from 62 women undergoing elective cesarean deliveries under regional anesthesia.The strips were pretreated with oxytocin 10−10, 10−8, 10−5 M, or physiological salt solution (control) for 2, 4, 6, or 12 h, followed by a dose–response testing with oxytocin 10−10 to 10−5 MAmplitude and frequency of contractions, motility index, and area under the curve during the dose–response period were recorded, analyzed with linear regression models, and compared among groups.

Results: Pretreatment with oxytocin , 10−5 and 10−8 M significantly reduced motility index (estimate [standard error]: −0.771 [0.270] square root units, P = 0.005 and −0.697 [0.293], P = 0.02, respectively) and area under the curve (−3.947 [1.909], P = 0.04 and −4.241 [2.189], P = 0.05, respectively) compared with control group, whereas pretreatment with oxytocin 10−10 M did not significantly attenuate contractions. Increase in duration of oxytocin pretreatment from 2 to 12 h significantly decreased amplitude (type 3 generalized estimating equation analysis: chi-square = 14.0; df = 3; P = 0.003), motility index (chi-square = 9.3; df = 3; P = 0.03), and area under the curve (chi-square = 10.5; df = 3; P = 0.02), but not the frequency of oxytocin-induced contractions.

Conclusion: Pretreatment with oxytocin decreases oxytocin-induced myometrial contractions in a concentration and time-dependent manner, likely as a function of the oxytocin receptor desensitization phenomenon.

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10 de setembro de 2013

Artigo recomendado: Prospective Randomized Crossover Study of a New Closed-loop Control System versus Pressure Support during Weaning from Mechanical Ventilation

Noémie Clavieras, Marc Wysocki, Yannael Coisel, Fabrice Galia, Matthieu Conseil, Gerald Chanques, Boris Jung, Jean-Michel Arnal, Stefan Matecki, Nicolas Molinari, Samir Jaber

Anesthesiology 2013; 119:631-41; Clavieras et al.

Background: Intellivent is a new full closed-loop controlled ventilation that automatically adjusts both ventilation and oxygenation parameters. The authors compared gas exchange and breathing pattern variability of Intellivent and pressure support ventilation (PSV).
Methods: In a prospective, randomized, single-blind design crossover study, 14 patients were ventilated during the weaning phase, with Intellivent or PSV, for two periods of 24 h in a randomized order. Arterial blood gases were obtained after 1, 8, 16, and 24 h with each mode. Ventilatory parameters were recorded continuously in a breath-by-breath basis during the two study periods. The primary endpoint was oxygenation, estimated by the calculation of the difference between the Pao2/Fioratio obtained after 24 h of ventilation and the Pao2/Fioratio obtained at baseline in each mode. The variability in the ventilatory parameters was also evaluated by the coefficient of variation (SD to mean ratio).
Results: There were no adverse events or safety issues requiring premature interruption of both modes. The Pao2/Fio2 (mean ± SD) ratio improved significantly from 245 ± 75 at baseline to 294 ± 123 (P = 0.03) after 24 h of Intellivent. The coefficient of variation of inspiratory pressure and positive end-expiratory pressure (median [interquartile range]) were significantly higher with Intellivent, 16 [11–21] and 15 [7–23]%, compared with 6 [5–7] and 7 [5–10]% in PSV. Inspiratory pressure, positive end-expiratory pressure, and Fio2 changes were adjusted significantly more often with Intellivent compared with PSV.
Conclusions: Compared with PSV, Intellivent during a 24-h period improved the Pao2/Fio2 ratio in parallel with more variability in the ventilatory support and more changes in ventilation settings.

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6 de setembro de 2013

Artigo recomendado: Different Propofol–Remifentanil or Sevoflurane–Remifentanil Bispectral Index Levels for Electrocorticographic Spike Identification during Epilepsy Surgery

Ashraf A. Dahaba, Jian Yin, Zhaoyang Xiao, Jing Su, Helmar Bornemann, Hailong Dong, Lize Xiong

Anesthesiology 2013; 119:582-92; Dahaba et al.


Background: Medical therapy, the cornerstone of managing epilepsy, still fails a substantial portion of patients. Little information is available regarding the potential impact of different bispectral index (BIS) levels on electrocorticographic spike identification for surgical epileptic foci resection.

Methods: Twenty-two intractable epilepsy subjects were randomly allocated to the propofol–remifentanil or sevoflurane–remifentanil groups, and were further randomized to four BIS85 (BIS 71–85), BIS70 (BIS 56–70), BIS55 (BIS 41–55), and BIS40 (BIS ≤40) sequence order.

Results: Two-way ANOVA revealed no differences between groups in spike frequency (P = 0.720), spike amplitude (P = 0.647), or number of spiking leads (P = 0.653). In the propofol and sevoflurane groups, decreasing BIS levels increased mean ± SD spike/min frequency (P < 0.001 and P < 0.001) at BIS85 (10 ± 12 and 10 ± 8), BIS70 (19 ± 17 and 17 ± 15), BIS55 (22 ± 17 and 18 ± 8), and BIS40 (25 ± 15 and 23 ± 17). Furthermore, in the propofol and sevoflurane groups, decreasing BIS levels increased spike microvolt amplitude (P = 0.006 and P = 0.009) at BIS85 (1,100 ± 400 and 750 ± 400), BIS70 (1,200 ± 460 and 850 ± 490), BIS55 (1,300 ± 560 and 940 ± 700), and BIS40 (1,400 ± 570 and 1,300 ± 700). Whereas, in the propofol and sevoflurane groups, there was no difference in the location or number of spiking leads (P = 0.057 and P = 0.109) at the four BIS levels. Compared with BIS85, spike frequency in the propofol and sevoflurane groups increased 100 and 170% at BIS70, 116 and 180% at BIS55, and 132 and 230% at BIS40. Compared with BIS85, spike amplitude increased 108 and 113% at BIS70, 121 and 125% at BIS55, and 128 and 170% at BIS40.

Conclusion: Decreasing BIS levels in the propofol and sevoflurane groups enhanced epileptogenic spike frequency and amplitude with the same location and number of spiking leads.

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3 de setembro de 2013

Artigo recomendado: Neuraxial Anesthesia in Parturients with Intracranial Pathology

A Comprehensive Review and Reassessment of Risk

Lisa R. Leffert, Lee H. Schwamm
Anesthesiology 2013; 119:703-18; L. R. Leffert and L. H. Schwamm


Parturients with intracranial lesions are often assumed to have increased intracranial pressure, even in the absence of clinical and radiographic signs. The risk of herniation after an inadvertent dural puncture is frequently cited as a contraindication to neuraxial anesthesia. This article reviews the relevant literature on the use of neuraxial anesthesia in parturients with known intracranial pathology, and proposes a framework and recommendations for assessing risk of neurologic deterioration, with epidural analgesia or anesthesia, or planned or inadvertent dural puncture. The authors illustrate these concepts with numerous case examples and provide guidance for the practicing anesthesiologist in determining the safety of neuraxial anesthesia.

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