Anesthesiology
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Comparative Study
The effect of cricoid pressure on preventing gastric insufflation in infants and children.
The use of cricoid pressure for the possible prevention of regurgitation of gastric contents during induction of anesthesia in both adults and children has been recommended. However, equally important is the technique in possibly preventing insufflation of gas into the stomach. This study was designed to determine the efficacy of cricoid pressure application in preventing gastric gas insufflation in pediatric patients and to determine the airway pressure at which gas entered the stomach (pop-off point). ⋯ Appropriate application of cricoid pressure prevents gastric gas insufflation during airway management via mask up to 40 cm H2O PIP in infants and children. An additional benefit of cricoid pressure occurs in paralyzed patients in whom gastric insufflation occurs at lower inflation pressures.
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Clinical Trial
Effect of a vecuronium-induced partial neuromuscular block on hypoxic ventilatory response.
A previous study has demonstrated a decrease in the hypoxic ventilatory response in volunteers partially paralyzed with vecuronium. However, in this study, hypocapnia was allowed to occur. Because hypocapnia counteracts the ventilatory response to hypoxia during partial vecuronium-induced neuromuscular block and isocapnia, the hypoxic ventilatory response (HVR) was tested in 10 awake volunteers. ⋯ We conclude that a vecuronium-induced partial neuromuscular block impairs HVR more than it does HCVR in humans, suggesting an effect of vecuronium on carotid body hypoxic chemosensitivity.
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The subcutaneous injection of formalin in the rat paw results in several minutes of flinching (phase 1) followed by cessation of activity then resumption of flinching (phase 2), which depends on facilitation of spinal transmission evoked by C-fiber activity generated immediately after the noxious stimulus. It was hypothesized that suppression of dorsal horn activity during and immediately after formalin injection by inhalation anesthetics or intrathecal opiates would block spinal facilitation and inhibit phase 2 flinching, even if the anesthetic or opiate were eliminated before phase 2. ⋯ Isoflurane, even at high concentrations, administered during and shortly after a noxious stimulus produces only a modest reduction in facilitation of afferent processing. The addition of intrathecal morphine during the period of nociceptor activity results in marked attenuation of the facilitated state.
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Previous reports suggest that the outcome (synergism, antagonism, summation) of opioid-barbiturate interactions may depend on the depth of anesthesia. One aim of the present study was to determine whether pentobarbital, alone and in combination with morphine, blocks awakening caused by noxious stimulation in a dose-related manner: the more intense the noxious stimulation, the more pentobarbital is required to suppress the response. A second aim of the study was to determine whether the pentobarbital-morphine anesthetic interaction depends on the depth of anesthesia measured in terms of intensity of noxious stimulation required for behavioral arousal (recovery of the righting reflex). ⋯ The results suggest that the depth of anesthesia can be measured in terms of intensity of noxious stimulation required for arousal and that the outcome of barbiturate-opioid anesthetic interaction depends on the depth of anesthesia.