Anesthesiology
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Randomized Controlled Trial Clinical Trial
Investigation of effective anesthesia induction doses using a wide range of infusion rates with undiluted and diluted propofol.
The influence of infusion rate on the induction dose-response relation has not been investigated over a wide range of infusion rates. In this study, the authors defined the effect of different propofol infusion rates on the times and doses necessary to reach clinical induction of anesthesia. ⋯ Induction dose and time are dependent on infusion rate in a complex manner, and residual dose circulation was a factor in overdose and hemodynamic depression. Hypotension during induction was attenuated by diluted propofol.
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Medical institutions are under increased economic pressure to schedule elective surgeries efficiently to contain the costs of surgical services. Surgical scheduling is complicated by variability inherent in the duration of surgical procedures. Modeling that variability, in turn, provides a mechanism to generate accurate time estimates. Accurate time estimates are important operationally to improve operating room utilization and strategically to identify surgeons, procedures, or patients whose duration of surgeries differ from what might be expected. ⋯ The authors recommend use of the log-normal model for predicting surgical procedure times for Current Procedural Terminology-anesthesia combinations. The results help to legitimize the use of log transforms to normalize surgical procedure times before hypothesis testing using linear statistical models or other parametric statistical tests to investigate factors affecting the duration of surgeries.
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Systemic administration of gabapentin was shown previously to attenuate mechanical allodynia in a rat model of postoperative pain. Because intrathecal administration of gabapentin is effective in other hypersensitivity states, the authors tested its effect in the postoperative model, its interaction with another antiallodynic agent (clonidine), and a possible mechanism of gabapentin action (entry into sites of action via an L-amino acid transporter). ⋯ Intrathecal gabapentin is effective against tactile allodynia that occurs after paw incision, and interacts synergistically with clonidine. Unlike results in vitro, gabapentin does not obligatorily need to enter cells via the L-amino acid transporter mechanism to achieve its effects in vivo.
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Background The neuronal mechanisms responsible for dissociative anesthesia remain controversial. N-methyl-D-aspartate (NMDA) receptors are inhibited by ketamine and related drugs at concentrations lower than those required for anesthetic effects. Thus, the authors studied whether ligand-gated ion channels other than NMDA receptors might display a sensitivity to ketamine and dizocilpine that is consistent with concentrations required for anesthesia. ⋯ Human nAChRs are inhibited by ketamine and dizocilpine at concentrations possibly achieved in vivo during anesthesia in a subunit-dependent manner, with beta subunits being more critical than alpha subunits. Conversely, 5-HT3, GABAA, and glycine receptors were relatively insensitive to dissociative anesthetics.
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In the current study, the potency and spread of the antinociception induced by MPV-2426, a novel alpha2-adrenoceptor agonist, was characterized in neuropathic and non-neuropathic animals. ⋯ Intrathecal MPV-2426 has spatially limited antinociceptive properties in neuropathic and non-neuropathic conditions because of its action on spinal alpha2-adrenoceptors. These properties may be advantageous when designing therapy for spatially restricted pain problems.