Articles: general-anesthesia.
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Randomized Controlled Trial Comparative Study Clinical Trial
Arterial oxygen saturation during induction of anaesthesia and laryngeal mask insertion: prospective evaluation of four techniques.
In a prospective, randomized study of 87 patients, we have compared the incidence of hypoxaemia during induction of anaesthesia with subsequent Laryngeal Mask Airway (LMA) insertion in healthy adults when four different techniques were used: one without supplementary oxygen, and three with supplementary oxygen. Twelve patients did not receive supplementary oxygen before LMA placement, 25 underwent partial denitrogenation by breathing oxygen from the start of injection of the induction agent, 25 underwent formal denitrogenation by breathing oxygen for 3 min, and 25 received five tidal volume breaths of oxygen by face mask using positive pressure immediately after induction of anaesthesia. Anaesthesia was induced with propofol 2.0 mg kg-1 and fentanyl 1 microgram kg-1. ⋯ Desaturation occurred in 11 of 12 patients who did not receive supplementary oxygen, and in 19 of 25 patients who received manual ventilation with 100% oxygen after induction of anaesthesia before LMA insertion. Full denitrogenation and partial denitrogenation were equally successful in preventing desaturation. Failure to position the LMA successfully occurred in 3% of patients, and some difficulty was encountered in another 18%.
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Comparative Study
Frequency and severity of desaturation events during general anesthesia in children with and without upper respiratory infections.
To determine whether anesthesia in the presence of a mild upper respiratory infection (URI) was associated with episodes of desaturation or reactive airway problems. ⋯ Children with a mild URI have an increased frequency of minor desaturation episodes, and intubated patients with a URI have an increased frequency of bronchospasm. It appears that children with a mild URI may be safely anesthetized, since the problems encountered are generally easily treated and without long-term sequelae.
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Comparative Study
Somatosensory and auditory evoked responses recorded simultaneously: differential effects of nitrous oxide and isoflurane.
Auditory (AER) and somatosensory evoked responses (SSER) were recorded simultaneously in eight patients under anaesthesia before surgery. We studied the effects of equi-MAC end-expiratory concentrations of isoflurane (0.65-0.75%) and nitrous oxide (60-65%). The anaesthetics were changed at random in three consecutive 10-min periods so that each patient received both drugs. ⋯ We were unable to demonstrate significant differences in Pa and Nb amplitude between isoflurane and nitrous oxide that we had seen previously. However, the amplitude of the SSER wave N20 was reduced significantly by nitrous oxide compared with isoflurane (P = 0.0004). This wave (N20) is thought to emanate from the thalamo-cortical radiations, and our findings may be explained by an analgesic effect of nitrous oxide mediated by endogenous opioids.