Anesthesiology
-
Randomized Controlled Trial Clinical Trial
Motor and somatosensory evoked potentials are well maintained in patients given dexmedetomidine during spine surgery.
Many commonly used anesthetic agents produce a dose-dependent amplitude reduction and latency prolongation of evoked responses, which may impair diagnosis of intraoperative spinal cord injury. Dexmedetomidine is increasingly used as an adjunct for general anesthesia. Therefore, the authors tested the hypothesis that dexmedetomidine does not have a clinically important effect on somatosensory and transcranial motor evoked responses. ⋯ Use of dexmedetomidine as an anesthetic adjunct at target plasma concentrations up to 0.6 ng/ml does not change somatosensory or motor evoked potential responses during complex spine surgery by any clinically significant amount.
-
Application of radiofrequency currents to the dorsal root ganglia, in the treatment of various pain syndromes, has been clinically practiced for more than 30 yr. The clinical efficacy and the safety of this technique, however, remain poorly understood. The authors reviewed the literature on this modality of pain relief to determine its clinical efficacy, safety, and mechanisms of action. ⋯ Five randomized controlled trials evaluated their clinical use; these trials were relatively short-termed and small in size, and their results were variable. The mechanism of action of these techniques was unclear. Larger controlled clinical trials evaluating the long-term effects of these techniques and basic science research to determine their precise mode of action are needed.
-
Clinical Trial
Using permutation entropy to measure the electroencephalographic effects of sevoflurane.
Approximate entropy (AE) has been proposed as a measure of anesthetic drug effect in electroencephalographic data. Recently, a new method called permutation entropy (PE) based on symbolic dynamics was also proposed to measure the complexity in an electroencephalographic series. In this study, the AE and PE were applied to electroencephalographic recordings for revealing the effect of sevoflurane on brain activity. The dose-response relation of PE during sevoflurane anesthesia was compared with that of AE. ⋯ The results show that PE can estimate the sevoflurane drug effect more effectively than AE. This method could be applied to design a new electroencephalographic monitoring system to estimate sevoflurane anesthetic drug effect.
-
Intraneural injection during peripheral nerve blockade can cause neurologic injury. Current approaches to prevent or detect intraneural injection lack reliability and consistency, or only signal intraneural injection upon the event. A change in electrical impedance (EI) could be indicative of intraneural needle placement before injection. ⋯ With further study, EI could prove to be a quantifiable warning signal to alert clinicians to intraneural needle placement, preventing local anesthetic injection and subsequent nerve injury.
-
Little is known regarding the final needle tip location when various intensities of nerve stimulation are used to guide block needle insertion. Therefore, in control and hyperglycemic dogs, the authors examined whether lower-intensity stimulation results in injection closer to the sciatic nerve than higher-threshold stimulation. ⋯ In normal dogs, current stimulation levels in the range of 0.33-1.0 mA result in needle placement comparably close to the sciatic nerve but do not correlate with distance from the target nerve. In this experimental design, low-threshold electrical stimulation does not offer satisfactory protection against intraneural injection in the presence of hyperglycemia.