ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundAll general anesthetics used are known to have a negative inotropic side effect. Since xenon does not have a negative inotropic effect, it could be an interesting future general anesthetic. The aim of this clinical multicenter trial was to test the hypothesis of whether recovery after xenon anesthesia is faster compared with an accepted, standardized anesthetic regimen and that it is as effective and safe.MethodA total of 224 patients in six centers were included in the protocol. They were randomly assigned to receive either xenon (60 ± 5%) in oxygen or isoflurane (end-tidal concentration, 0.5%) combined with nitrous oxide (60 ± 5%). Sufentanil (10 &mgr;g) was intravenously injected if indicated by defined criteria. Hemodynamic, respiratory, and recovery parameters, the amount of sufentanil, and side effects were assessed.ResultsThe recovery parameters demonstrated a statistically significant faster recovery from xenon anesthesia when compared with isoflurane–nitrous oxide. The additional amount of sufentanil did not differ between both anesthesia regimens. Hemodynamics and respiratory parameters remained stable throughout administration of both anesthesia regimens, with advantages for the xenon group. Side effects occurred to the same extent with xenon in oxygen and isoflurane–nitrous oxide.ConclusionThis first randomized controlled multicenter trial on the use of xenon as an inhalational anesthetic confirms, in a large group of patients, that xenon in oxygen provides effective and safe anesthesia, with the advantage of a more rapid recovery when compared with anesthesia using isoflurane–nitrous oxide.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundGeneral anesthesia is known to promote atelectasis formation. High inspiratory pressures are required to reexpand healthy but collapsed alveoli. However, in the absence of positive end-expiratory pressure (PEEP), reexpanded alveoli collapse again. Using magnetic resonance imaging, the impact of an alveolar recruitment strategy on the amount and distribution of atelectasis was tested.MethodsThe authors prospectively randomized 24 children who met American Society of Anesthesiologists physical status I or II criteria, were aged 6 months–6 yr, and were undergoing cranial magnetic resonance imaging into three groups. After anesthesia induction, in the alveolar recruitment strategy (ARS) group, an alveolar recruitment maneuver was performed by manually ventilating the lungs with a peak airway pressure of 40 cm H2O and a PEEP of 15 cm H2O for 10 breaths. PEEP was then reduced to and kept at 5 cm H2O. The continuous positive airway pressure (CPAP) group received 5 cm H2O of continuous positive airway pressure without recruitment. The zero end-expiratory pressure (ZEEP) group received neither PEEP nor the recruitment maneuver. All patients breathed spontaneously during the procedure. After cranial magnetic resonance imaging, thoracic magnetic resonance imaging was performed.ResultsThe atelectatic volume (median, first and third standard quartiles) detected in the ZEEP group was 1.25 (0.75–4.56) cm3in the right lung and 4.25 (3.2–13.9) cm3in the left lung. The CPAP group had 9.5 (3.1–23.7) cm3of collapsed lung tissue in the right lung and 8.8 (5.3–28.5) cm3in the left lung. Only one patient in the ARS group presented an atelectasis of less than 2 cm3. An uneven distribution of the atelectasis was observed within each lung and between the right and left lungs, with a clear predominance of the left basal paradiaphragmatic regions.ConclusionFrequency of atelectasis was much less following the alveolar recruitment strategy, compared with children who did not have the maneuver performed. The mere application of 5 cm H2O of CPAP without a prior recruitment did not show the same treatment effect and showed no difference compared to the control group without PEEP.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundMany healthcare professionals are trained in direct laryngoscopic tracheal intubation (LEI), which is a potentially lifesaving procedure. This study attempts to determine the number of successful LEI exposures required during training to assure competent performance, with special emphasis on defining competence itself.MethodsAnalyses were based on a longitudinal study of novices under training conditions in the operating room. The progress of 438 LEIs performed by the 20 nonanesthesia trainees was monitored by observation and videotape analysis. Eighteen additional LEIs were performed by experienced anesthesiologists to define the standard. A generalized linear, mixed-modelling approach was used to identify key aspects of effective training and performance. The number of tracheal intubations that the trainees were required to perform before acquiring expertise in LEI was estimated.ResultsSubjects performed between 18 and 35 laryngoscopic intubations. However, statistical modeling indicates that a 90% probability of a “good intubation” required 47 attempts. Proper insertion and lifting of the laryngoscope were crucial to “good” or “competent” performance of LEI. Traditional features, such as proper head and neck positions, were found to be less important under the study conditions.ConclusionsThis study determined that traditional LEI teaching for nonanesthesia personnel using manikin alone is inadequate. A reevaluation of current standards in LEI teaching for nonanesthesia is required.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundThe use of 100% oxygen during induction of anesthesia may produce atelectasis. The authors investigated how different oxygen concentrations affect the formation of atelectasis and the fall in arterial oxygen saturation during apnea.MethodsThirty-six healthy, nonsmoking women were randomized to breathe 100, 80, or 60% oxygen for 5 min during the induction of general anesthesia. Ventilation was then withheld until the oxygen saturation, assessed by pulse oximetry, decreased to 90%. Atelectasis formation was studied with computed tomography.ResultsAtelectasis in a transverse scan near the diaphragm after induction of anesthesia and apnea was 9.8 ± 5.2 cm2(5.6 ± 3.4% of the total lung area; mean ± SD), 1.3 ± 1.2 cm2(0.6 ± 0.7%), and 0.3 ± 0.3 cm2(0.2 ± 0.2%) in the groups breathing 100, 80, and 60% oxygen, respectively (P< 0.01). The corresponding times to reach 90% oxygen saturation were 411 ± 84, 303 ± 59, and 213 ± 69 s, respectively (P< 0.01).ConclusionDuring routine induction of general anesthesia, 80% oxygen for oxygenation caused minimal atelectasis, but the time margin before unacceptable desaturation occurred was significantly shortened compared with 100% oxygen.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundPropofol is reported to reduce both sympathetic and parasympathetic tone; however, it is not clear whether the changes in heart rate variability are associated with depth of anesthesia. The purposes of the present study were (1) to evaluate the changes in heart rate variability at different depths of hypnosis and (2) to compare the effects of propofol on heart rate variability with that of sevoflurane.MethodsThirty patients were randomly allocated into the propofol or sevoflurane for induction of anesthesia. The depth of hypnosis was monitored by the Bispectral Index (BIS). Spectral analysis of heart rate variability using a maximum-entropy method resulted in a characteristic power spectrum with two main regions, a high frequency (HF) and a low frequency (LF). Hemodynamics, entropy, LF, HF, and LF/HF were monitored when the patients were awake and after induction of anesthesia.ResultsBoth propofol and sevoflurane decreased blood pressure in a BIS-dependent manner, whereas heart rate showed no significant changes during the study period. In the propofol group, entropy and HF decreased with a reduction in the BIS value. Although LF decreased after induction of anesthesia, propofol caused no further decrease in LF in spite of a reduction in the BIS value. In the sevoflurane group, LF decreased with a reduction in the BIS value. Entropy and HF decreased after induction of anesthesia (BIS at 80); however, no further decreases were observed in spite of a reduction in the BIS value.ConclusionsInduction of anesthesia with propofol decreased blood pressure, entropy, and HF in a BIS-dependent manner, indicating that propofol reduces cardiac parasympathetic tone depending on the depth of hypnosis. Conversely, sevoflurane did not show the BIS-dependent decreases in heart rate, blood pressure, HF, and entropy, indicating that sevoflurane has little or no effect on cardiac parasympathetic tone.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundKnowledge of the influence of age on laryngeal dimensions is essential for all practitioners whose interest is the pediatric airway. Early cadaver studies documented that the larynx is conically shaped, with the apex of the cone caudally positioned at the nondistensible cricoid cartilage. These dimensions change during childhood, as the larynx assumes a more cylindrical shape. The authors analyzed laryngeal dimensions during development to determine if this relationship continues in unparalyzed children in whom laryngeal muscles are tonically active. The authors determined the relationships between the vocal cord, sub–vocal cord, and cricoid ring dimensions and the influence of age on these relationships.MethodsInfants and children undergoing magnetic resonance imaging with propofol sedation had determinations of the transverse and anterior–posterior (AP) dimensions of the larynx at the most cephalad level of the larynx (vocal cords) and the most caudad level (cricoid). Most patients had an additional measurement (sub–vocal cord) at a level between the vocal cords and the cricoid ring. Relationships were obtained by plotting age against laryngeal dimensions and the ratio of laryngeal dimensions at different levels within the larynx.ResultsThe authors measured transverse and AP laryngeal dimensions in 99 children, aged 2 months–13 yr. The relationship between the transverse and AP dimensions at all levels of the larynx did not change during development. Transverse and AP dimensions increased linearly with age at all levels of the larynx. In all children studied, the narrowest portion of the larynx was the transverse dimension at the level of the vocal cords. Transverse dimensions increased linearly in a caudad direction through the larynx (P< 0.001), while AP dimensions did not change relative to laryngeal level. The shape of the cricoid ring did not change throughout childhood.ConclusionsIn sedated, unparalyzed children, the narrowest portions of the larynx are the glottic opening (vocal cord level) and the immediate sub–vocal cord level, and there is no change in the relationships of these dimensions relative to cricoid dimensions throughout childhood.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundIt is commonly stated that risk factors for postoperative nausea are the same as for vomiting. The authors designed a prospective study to identify and differentiate the risk factors for postoperative nausea and vomiting in various surgical populations in a clinical audit setting.MethodsThe study included 671 consecutive surgical inpatients, aged 15 yr or more, undergoing various procedures. The study focused on postoperative nausea visual analog scale scores every 4 h and vomiting episodes within 72 h. Both vomiting and retching were considered as emetic events. Patient-, anesthesia-, and surgery-related variables that were considered to have a possible effect on the proportion of patients experiencing postoperative nausea and/or vomiting were examined. The bivariate Dale model for binary correlated outcomes was used to identify selectively the potential risk factors of postoperative nausea and vomiting.ResultsAmong the 671 patients in the study, 126 (19%) reported one or more episodes of nausea, and 66 patients (10%) suffered one or more emetic episodes during the studied period. There was a highly significant association between the two outcomes. Some risk factors were predictive of both nausea and vomiting (female gender, nonsmoking status, and general anesthesia). History of migraine and type of surgery were mainly responsible for nausea but not for vomiting. The predictive effect of risk factors was controlled for postoperative pain and analgesic drugs.ConclusionThis study shows that differences exist in risk factors of postoperative nausea and vomiting. These could be explained by differences in the physiopathology of the two symptoms.

ISSN:0003-3022    

出版商:OVID    

年代:2003

数据来源: OVID