Anesthesia and analgesia
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Anesthesia and analgesia · May 1995
Randomized Controlled Trial Clinical TrialThe effects of chewing gum on gastric content prior to induction of general anesthesia.
To study the effects on gastric content and subjective well being of chewing gum in the immediate preoperative period, 60 female nonsmokers were randomized to use regular, sugar-free chewing gum preoperatively or to continue the overnight fast. In a similar fashion 44 habitual smokers were randomized to use nicotine gum 2 mg or not. Nonsmokers using chewing gum had significantly larger gastric fluid volumes than controls (mean 30 +/- 19 mL vs 20 +/- 15 mL; 95% confidence interval (CI) for difference 1-19 mL; P = 0.03), with no difference in gastric fluid acidity. ⋯ Although the use of nicotine gum in smokers was associated with a reduction in dryness of the mouth, thirst, and irritability, nonsmokers chewing regular gum did not report significant improvements in patient well being. In habitual smokers unable to abstain from nicotine, the use of nicotine gum on the morning of surgery may be beneficial. Although it is difficult to prove a direct influence on the incidence of pulmonary aspiration of increased gastric contents, the fact that regular, sugar-free chewing gum increased gastric fluid volumes probably means that it should not be used on the morning of surgery.
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Anesthesia and analgesia · May 1995
Randomized Controlled Trial Comparative Study Clinical TrialThe incidence of gastroesophageal reflux with the laryngeal mask: a comparison with the face mask using esophageal lumen pH electrodes.
To test the hypothesis that the laryngeal mask airway (LMA) predisposes patients to gastroesophageal reflux, we randomly assigned 55 patients having elective surgery to receive standardized anesthesia with the LMA or with conventional face mask (FM) plus airway. A pH-sensitive probe with two electrodes, 10 cm apart, was passed nasally into the esophagus 1 h before induction of anesthesia, and recordings were made continuously until 30 min after surgery. At the distal electrode, 30 cm from the anterior nares, there was a significant difference in the incidence of reflux: 53.6% with the LMA versus 22.2% with the FM (P < 0.05). ⋯ Reflux events continued in the postanesthesia care unit (PACU) in both groups with no significant difference between groups. There was no clinical evidence of aspiration of gastric contents in either group. Use of the LMA appears to result in increased reflux to the level of the mid to upper esophagus, and is associated with a more frequent incidence of multiple reflux events than use of the FM.
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Anesthesia and analgesia · May 1995
The effect of graded hemorrhage and intravascular volume replacement on systolic pressure variation in humans during mechanical and spontaneous ventilation.
In dogs and humans, the magnitude of the variation in systolic pressure (SPV) over the respiratory cycle during mechanical ventilation appears to be inversely related to intravascular volume. Also reported to correlate with changes in volume status is delta down, the difference between systolic pressure at end-expiration and the lowest value during the respiratory cycle. These variables were examined during graded hemorrhage in eight anesthetized, mechanically ventilated subjects, and seven awake, spontaneously breathing subjects. ⋯ After hetastarch, both SPV and delta down were smaller than at baseline and may explain why the infusion of NS caused nonsignificant reductions in SPV and delta down. A SPV of 5 mm Hg or less, or a delta down of 2 mm Hg or less appeared to indicate minimal intravascular volume depletion. During spontaneous ventilation, delta down could not be determined accurately in several subjects, and SPV did not change in the appropriate direction in all cases of hemorrhage and volume infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · May 1995
Effects of sevoflurane on the middle latency auditory evoked response and the electroencephalographic power spectrum.
We investigated the effects of sevoflurane on the middle latency auditory evoked response (MLR) and the power spectrum of the electroencephalogram (EEG) in 10 elective surgical patients. The MLR and the EEG power spectrum were recorded with a surface electrode placed at the central (Cz) scalp location. End-tidal sevoflurane concentrations of 0%, 0.25%, 0.5%, 0.75%, 1.0%, and 1.5% in 50% nitrous oxide and oxygen were studied. ⋯ The beta power, median power frequency (MPF), and 95% spectral edge frequency (SEF) decreased significantly according to the increases by 0.5% sevoflurane. Regarding the changes evoked by 0.25% sevoflurane, the Nb latency of the MLR responded significantly under 0.75% of sevoflurane. At these low concentrations of sevoflurane, the MLR seemed to be more sensitive to changes in anesthetic concentration than the various EEG variables.