Anesthesiology
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Comparison of the intubating laryngeal mask airway with the fiberoptic intubation in anticipated difficult airway management.
The intubating laryngeal mask airway (ILMA; Fastrach; Laryngeal Mask Company, Henley-on-Thames, UK) may provide an alternative technique to fiberoptic intubation (FIB) to facilitate the management of the anticipated difficult airway. The authors therefore compared the effectiveness of the ILMA with FIB in patients with anticipated difficult intubation. ⋯ The authors obtained a high success rate and comparable duration of tracheal intubation with ILMA and FIB techniques. In patients with previous cervical radiotherapy, the use of ILMA cannot be recommended. Nevertheless, the use of the ILMA was associated with fewer adverse events.
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Positive modulation of gamma-aminobutyric acid type A (GABAA) receptor function is recognized as an important component of the central nervous system depressant effects of many general anesthetics, including propofol. The role for GABAA receptors as an essential site in the anesthetic actions of propofol was recently challenged by a report that the propofol analog 4-iodopropofol (4-iodo-2,6-diisopropylphenol) potentiated and directly activated GABAA receptors, yet was devoid of sedative-anesthetic effects in rats after intraperitoneal injection. Given the important implications of these findings for theories of anesthesia, the authors compared the effects of 4-iodopropofol with those of propofol using established in vivo and in vitro assays of both GABAA receptor-dependent and -independent anesthetic actions. ⋯ Propofol and 4-iodopropofol produced similar actions on several previously identified cellular and molecular targets of general anesthetic action, and both compounds induced anesthesia in tadpoles and rats. The failure of 4-iodopropofol to induce anesthesia in rodents after intraperitoneal injection is attributed to a pharmacokinetic difference from propofol rather than to major pharmacodynamic differences.
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Spinal N-methyl-D-aspartate (NMDA) receptor activation has been demonstrated to play an important role in the processing of spinal nociceptive information and in the determination of the minimum alveolar anesthetic concentration (MAC) of inhalational anesthetics. Postsynaptic density-95 (PSD-95)/synapse-associated protein-90 (SAP90), a molecular scaffolding protein that binds and clusters the NMDA receptor perferentially at synapses, was implicated in NMDA-induced thermal hyperalgesia. The current study investigated the possible involvement of PSD-95/SAP9O in determining MAC for isoflurane anesthesia. ⋯ The results indicate not only a significant decrease in MAC for isoflurane but also an attenuation in the NMDA-induced increase in isoflurane MAC in the PSD-95/SAP90 antisense-treated animals, which suggests that PSD-95/SAP90 may mediate the role of the NMDA receptor in determining the MAC of inhalational anesthetics.
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Randomized Controlled Trial Clinical Trial
Propofol alters the pharmacokinetics of alfentanil in healthy male volunteers.
The influence of propofol on the pharmacokinetics of alfentanil is poorly understood. The authors therefore studied the effect of a pseudo-steady state concentration of propofol on the pharmacokinetics of alfentanil. ⋯ Propofol alters the pharmacokinetics of alfentanil. Hemodynamic changes induced by propofol may have an important influence on the pharmacokinetics of alfentanil.
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Clinical Trial
Response surface modeling of alfentanil-sevoflurane interaction on cardiorespiratory control and bispectral index.
Respiratory depression is a serious side effect of anesthetics and opioids. The authors examined the influence of the combined administration of sevoflurane and alfentanil on ventilatory control, heart rate (HR), and Bispectral Index (BIS) in healthy volunteers. ⋯ Response surface modeling was used successfully to analyze the effect of interactions between two drugs on respiration. The combination of alfentanil and sevoflurane causes more depression of Vi and HR than does the summed effect of each drug administered separately. The effects of combining alfentanil and sevoflurane on hypoxic Vi and HR responses and BIS could be predicted from the separate dose-response curves. Over the dose range tested, the hypoxic response is more sensitive to the effects of anesthetics and opioids relative to resting ventilation.