Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1990
Randomized Controlled Trial Comparative Study Clinical TrialPreoxygenation in the elderly: a comparison of the four-maximal-breath and three-minute techniques.
To compare the effectiveness of two routinely used methods of preoxygenation in protecting against hypoxia in the elderly, the arterial O2 saturation was measured using an oximeter. Twenty-four elderly patients (greater than or equal to 65 yr) presenting for elective orthopedic surgery were randomly allocated to receive either 3-min or four-maximal-breaths of 100% O2 via a Bain circuit. ⋯ Although attaining similar arterial O2 saturation values after preoxygenation, patients in the four-maximal-breath group had significantly shorter times (P less than 0.0001) to all levels of desaturation. We suggest that preoxygenation with 3-min breathing of 100% O2 offers more protection against hypoxia due to prolonged apnea after induction of anesthesia in the elderly than does four maximal breaths of 100% O2.
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Anesthesia and analgesia · Nov 1990
Randomized Controlled Trial Comparative Study Clinical TrialCorrelation of train-of-four and double burst stimulation ratios at varying amperages.
The present study was undertaken to document the relationship between train-of-four (TOF) and double burst stimulation (DBS) at varying degrees of blockade, and to determine whether this relationship remained constant over a range of stimulating currents. The neuromuscular responses to the two most commonly employed modes of DBS stimulation, DBS3,3 and DBS3,2, and the responses to TOF nerve stimulation were recorded and compared at 20, 30, and 50 mA. Twenty-two consenting patients undergoing general anesthesia received a vecuronium infusion to achieve a TOF ratio within the range of 0.1-1.0. ⋯ Similarly, there was a high degree of correlation between DBS3,2 and TOF at 50 mA, as the increased "fade" associated with DBS3,2 was maintained throughout the spectrum of blockade (P less than 0.0001; r = 0.95). The high degrees of correlation were maintained at stimulating currents of 20 and 30 mA (P less than 0.0001). In conclusion, the present study revealed that there is a high degree of linear correlation between DBS and TOF, and that this mechanographic relationship is maintained over a wide range of stimulating currents during varying degrees of clinical neuromuscular blockade.
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Anesthesia and analgesia · Nov 1990
Randomized Controlled Trial Clinical TrialIs the antiemetic effect of the emulsion formulation of propofol due to the lipid emulsion?
The hypothesis that the lipid emulsion of the emulsion formulation of propofol is responsible for the low frequency of nausea, retching, and vomiting after propofol anesthesia was tested. A randomized, prospective, and comparative study was performed to evaluate the antiemetic effect of 10% lipid solution in 60 women, ASA physical status I and II, scheduled for ambulatory laparoscopic procedures. Two groups of patients were studied. ⋯ The groups were similar with respect to duration of anesthesia, characteristics of early and intermediate recovery, as well as pain scores in the postanesthesia care unit. There were no differences in the amount of antiemetic medications administered or postoperative nausea, retching, or vomiting when the patients were evaluated objectively by a blinded observer or subjectively by patient self-evaluation. It is concluded that 10% Intralipid, the lipid in the emulsion formulation of propofol, does not possess significant antiemetic effects.
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The 40-Hz auditory steady-state evoked response (ASSR) is a sinusoidal electrical response of the brain to periodically presented auditory stimuli. It was recorded during anesthesia in 10 elective surgical patients to evaluate its usefulness as a measure of the level of consciousness. The anesthetic agents used were thiopental, fentanyl, and isoflurane with or without nitrous oxide. ⋯ The changes of the ASSR paralleled those of the level of consciousness. The EEG measurements were distorted by the presence of muscle artifacts that were prominent during emergence and recovery. The amplitude of the ASSR appears to provide a more reliable indicator of the level of consciousness than the EEG.