Anesthesia and analgesia
-
Anesthesia and analgesia · Jan 2001
Comparative StudyIntraoperative monitoring in neuroanesthesia: a national comparison between two surveys in Germany in 1991 and 1997. Scientific Neuroanesthesia Research Group of the German Society of Anesthesia and Intensive Care Medicine.
Two surveys initiated by the Neuroanesthesia Research Group of the German Society of Anesthesia and Intensive Care Medicine examined the practice of intraoperative monitoring during intracranial procedures in Germany in 1991 and 1997. Questionnaires were mailed to departments that were registered members of the German Society of Anesthesia and Intensive Care Medicine and that provided neuroanesthesia service on a routine basis in 1991. In 1997, the survey was repeated in the 1991 respondents. In 1991, 68 departments and in 1997, 44 departments returned completed questionnaires, indicating a response rate of 87% for 1991 and of 65% for 1997. Compared with 1991, the standards for monitoring, such as surveillance of oxygenation, ventilation, circulation, and body temperature, were universally applied in adult and pediatric patients in 1997. Overall, there was a 20% increase in neuromuscular blockade monitoring and in the use of electroencephalography and evoked potentials in 1997 compared with 1991. Further brain-specific monitoring was rarely provided in 1997. Overall, jugular venous oximetry was used in 20% and transcranial Doppler ultrasonography in 15% of responding hospitals. To detect venous air embolism in sitting patients, 75% of all responding hospitals used precordial Doppler ultrasonography in both years, whereas transesophageal echocardiography was more often used in 1997 (38%) as compared with 1991 (17%). ⋯ Standards of anesthetic monitoring were surveyed in neuroanesthesia in Germany in 1991 and 1997. Central nervous system monitoring was not the standard of practice.
-
Anesthesia and analgesia · Jan 2001
Neither GABA(A) nor strychnine-sensitive glycine receptors are the sole mediators of MAC for isoflurane.
Inhaled anesthetics produce immobility (a cardinal aspect of general anesthesia) by an action on the spinal cord, possibly by potentiating the responses of gamma-amino-n-butyric acid (GABA(A)) and glycine receptors to GABA and glycine. In this study, we antagonized GABA(A) and glycine responses by intrathecal administration of picrotoxin (a noncompetitive GABA(A) antagonist), strychnine (a competitive glycine antagonist), or combinations of these drugs. We measured the capacity of antagonist infusion to increase isoflurane MAC (the minimum alveolar concentration of anesthetic that prevents movement in response to noxious stimuli in 50% of subjects). We found that these potent GABA(A) and glycine receptor antagonists had a ceiling effect, either alone or in combination increasing the MAC of isoflurane by at most 47%. ⋯ gamma-amino-n-butyric acid and glycine receptors may in part be responsible for the immobilizing action of isoflurane. They are not, however, the only receptors that contribute to isoflurane-induced immobility (i.e., that determine the MAC of isoflurane).
-
Anesthesia and analgesia · Jan 2001
Clinical TrialThe minimum alveolar concentration of enflurane for laryngeal mask airway extubation in deeply anesthetized children.
The end-tidal anesthetic gas concentration required to prevent the anesthetized patient from coughing or moving during or immediately after the laryngeal mask airway (LMA) extubation is not known. We sought to determine the minimum alveolar concentration of enflurane required for the removal of the LMA in children. We studied 21 nonpremedicated children between 4 and 11 yr of age, ASA physical status I, undergoing procedures below the umbilicus. General anesthesia was induced with a mask by using sevoflurane, nitrous oxide, and oxygen, and the LMA was inserted. Anesthesia was maintained with enflurane, nitrous oxide, and oxygen. At the end of surgery, a predetermined end-tidal enflurane concentration was achieved, and the LMA was removed. Each concentration at which the LMA extubation was attempted was predetermined by the up-and-down method (with 0.1% as a step size). When LMA removal was accomplished without coughing, clenching teeth, or gross purposeful muscular movements during or within 1 min after removal, it was considered a successful LMA removal. Removal was considered to be unsuccessful in patients who developed breath holding or laryngospasm during or immediately after LMA removal. The minimum alveolar concentration of enflurane at which 50% of children had a successful LMA removal was found to be 1.02% (95% CL, 0.95%-1.11%), and the 95% effective dose for successful extubation was 1.14% (95% CL, 1.07%-1.66%). In conclusion, the LMA removal may be accomplished without coughing or moving at 1.02% end-tidal enflurane concentration in 50% of anesthetized children aged 4-11 yr. ⋯ There may be fewer problems associated with the laryngeal mask airway extubation when patients are deeply anesthetized. The purpose of this study was to determine the minimum concentration of enflurane for successful removal of the laryngeal mask in children.
-
Anesthesia and analgesia · Jan 2001
Awake craniotomy for removal of intracranial tumor: considerations for early discharge.
We retrospectively reviewed the anesthetic management, complications, and discharge time of 241 patients undergoing awake craniotomy for removal of intracranial tumor to determine the feasibility of early discharge. The results were analyzed by using univariate analysis of variance and multiple logistic regression. The median length of stay for inpatients was 4 days. Fifteen patients (6%) were discharged 6 h after surgery and 76 patients (31%) were discharged on the next day. Anesthesia was provided by using local infiltration supplemented with neurolept anesthesia consisting of midazolam, fentanyl, and propofol. There was no significant difference in the total amount of sedation required. Overall, anesthetic complications were minimal. One patient (0.4%) required conversion to general anesthesia and one patient developed a venous air embolus. Fifteen patients (6%) had self-limiting intraoperative seizures that were short-lived. Of the 16 patients scheduled for ambulatory surgery, there was one readmission and one unanticipated admission. It may be feasible to discharge patients on the same or the next day after awake craniotomy for removal of intracranial tumor. However, caution is advised and patient selection must be stringent with regards to the preoperative functional status of the patient, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission. ⋯ It may be feasible to perform awake craniotomies for removal of intracranial tumor as an ambulatory procedure; however, caution is advised. Patient selection must be stringent with respect to the patient's preoperative functional status, tumor depth, surrounding edema, patient support at home, and ease of access to hospital for readmission.
-
Anesthesia and analgesia · Jan 2001
Comparative StudyThe effects of lidocaine on nitric oxide production from an activated murine macrophage cell line.
Nitric oxide (NO), overproduced by activated macrophages, is important in the pathogenesis of various diseases, including septic shock and inflammatory tissue injury, as well as antibacterial host defense mechanisms. We examined the effects of lidocaine on NO production and the expression of inducible NO synthase (iNOS) protein and messenger RNA (mRNA) in activated macrophages. Murine macrophage-like cell line RAW 264 was stimulated for 8 h with lipopolysaccharide (10 mg/mL) and interferon-gamma (50 U/mL) in the presence of various concentrations of lidocaine (0-500 mg/mL). NO production was assessed by measuring levels of the stable metabolites, nitrite and nitrate (NOx), in the culture medium with an automatic analyzer using the Griess reaction. Expression of iNOS mRNA in harvested RAW 264 was quantified by Northern blot analysis using mouse iNOS complementary DNA probe. Expression of iNOS protein in the cells was assessed by Western blot analysis using anti-iNOS antibody. Lidocaine dose-dependently attenuated the increase in NOx levels in response to the stimulants. The drug at any concentration failed to decrease iNOS mRNA expression in RAW 264. Lidocaine at 500 mg/mL decreased iNOS protein levels. These data suggest that lidocaine reduced NO production in activated macrophages at multiple levels after transcription. The inhibitory site appeared to vary with the dose of lidocaine. ⋯ Lidocaine dose-dependently inhibited nitric oxide production by activated macrophages, presumably at levels after transcription. The attenuating effect of lidocaine on organ injuries previously reported may be explained by the ability of the drug to suppress this inflammatory mediator.