Anesthesiology
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Clinical Trial Controlled Clinical Trial
Efficacy of the self-inflating bulb in confirming tracheal intubation in the morbidly obese.
This study was designed to determine the incidence of false-negative and false-positive results when the self-inflating bulb (SIB) is used to differentiate tracheal from esophageal intubation in morbidly obese patients using two techniques. In technique 1, the SIB is compressed before it is connected to the tube; in technique 2, the SIB is compressed after connection to the tube. ⋯ Contrary to previous investigations in healthy patients, the current study demonstrates a high incidence of false-negative results when the SIB is used to confirm tracheal intubation in morbidly obese patients. If the SIB is used, the technique should include compression of the SIB after connection to the tube and should be used in conjunction with other clinical signs and technical aids. The mechanism of false-negative results in these patients seems to be related to reduction of caliber of airways secondary to a marked decrease in functional residual capacity, and collapse of large airways due to invagination of the posterior tracheal wall when sub-atmospheric pressure is generated by the SIB.
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Randomized Controlled Trial Clinical Trial
Analgesic efficacy of low-dose ketamine. Somatosensory-evoked responses in relation to subjective pain ratings.
Low-dose ketamine has been shown to exert analgesic effects. Whether ketamine-induced pain relief may be quantitated by somatosensory evoked cerebral potentials has not been established. ⋯ These data indicate that pain relief induced by low-dose ketamine is dose-dependent for the first 30 min after bolus injection. Changes in pain perception may be quantitated by somatosensory-evoked cortical responses. Also, EEG changes are not specific for changes in nociception, but the increase in theta power may reflect the hypnotic effect of low-dose ketamine.
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Clinical Trial
Intramuscular rocuronium in infants and children. Dose-ranging and tracheal intubating conditions.
Rocuronium's rapid onset and intermediate duration of action with intravenous administration suggests that intramuscular administration might facilitate tracheal intubation without producing prolonged paralysis. Accordingly, in infants and children, the authors measured onset at the adductor pollicis and respiratory muscles to determine the optimal dose (phase I), then gave this optimal dose to determine the optimal time for tracheal intubation (phase II). ⋯ Deltoid injections of rocuronium, 1,000 micrograms/kg in infants and 1,800 micrograms/kg in children, rapidly permit tracheal intubation in infants and children, despite a light plane of anesthesia. Duration of action of these large doses might limit clinical utility.
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Comparative Study
Acute pain and central nervous system arousal do not restore impaired hypoxic ventilatory response during sevoflurane sedation.
To quantify the effects of acute pain on ventilatory control in the awake and sedated human volunteer, the acute hypoxic ventilatory response was studied in the absence and presence of noxious stimulation before and during 0.1 minimum alveolar concentration sevoflurane inhalation. ⋯ The observation that acute pain caused an increase in baseline ventilation with no effect on the acute hypoxic ventilatory response indicates that acute pain interacted with ventilatory control without modifying the effect of low-dose sevoflurane on the peripheral chemoreflex loop. Acute pain increased the level of arousal significantly during sevoflurane inhalation but did not restore the approximately 30% depression of the acute hypoxic ventilatory response by sevoflurane. The central nervous system arousal state per se did not contribute to the impairment of the acute hypoxic ventilatory response by sevoflurane.
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Comparative Study
Heparinase I (neutralase) reversal of systemic anticoagulation.
Protamine causes multiple adverse reactions. Heparinase I, a specific enzyme that inactivates heparin, is a possible alternative to protamine. In this study, the authors examined the efficacy of heparinase I to reverse heparin-induced anticoagulation in vitro and compared heparinase I to protamine as an antagonist of heparin-induced anticoagulation in dogs. ⋯ Both heparinase I and protamine effectively reversed heparin anticoagulation. However, as opposed to protamine, heparinase I did not produce any significant hemodynamic changes when given as a bolus to dogs.