Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2009
Comparative StudyRat dorsal horn nociceptive-specific neurons are more sensitive than wide dynamic range neurons to depression by immobilizing doses of volatile anesthetics: an effect partially reversed by the opioid receptor antagonist naloxone.
The mechanism and site of action within the spinal cord by which volatile anesthetics produce immobility are not well understood. Little work has been done directly comparing anesthetic effects on neurons with specific functional characteristics that mediate transfer of nociceptive information within the spinal cord. ⋯ NS but not WDR neurons in the lumbar dorsal horn are depressed by peri-MAC increases of halothane and isoflurane. This depression, at least with halothane, can be partially reversed by the opioid antagonist naloxone. Given that opioid receptors are not likely involved in the mechanisms by which volatile anesthetics produce immobility, this suggests that, although the neuronal depression is of substantial magnitude and occurs concurrent to the production of immobility, it may not play a major role in the production of this anesthetic end point.
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Anesthesia and analgesia · Aug 2009
Comparative StudyA comparison of stroke volume variation measured by Vigileo/FloTrac system and aortic Doppler echocardiography.
The goal of this study was to compare stroke volume variation (SVV) assessed from a peripheral artery with the Vigileo/FloTrac system (SVV-FloTrac) with SVV derived close to the heart by aortic Doppler (SVV-Doppler). ⋯ SVV-FloTrac and SVV-Doppler measurements show acceptable bias and limits of agreement, and similar performance in terms of fluid responsiveness in patients undergoing liver transplantation.
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Anesthesia and analgesia · Aug 2009
The effects of steep trendelenburg positioning on intraocular pressure during robotic radical prostatectomy.
Intraocular pressure (IOP) increases in steep Trendelenburg positioning, but the magnitude of the increase has not been quantified. In addition, the factors contributing to this increase have not been studied in robot-assisted prostatectomy cases. In this study, we sought to quantify the changes in IOP and examine perioperative factors responsible for these changes while patients are in the steep Trendelenburg position during robotic prostatectomy. ⋯ IOP reached peak levels at the end of steep Trendelenburg position (T5), on average 13 mm Hg higher than the preanesthesia induction (T1) value. Surgical duration and ETco(2) were the only significant predictors of IOP increase in the Trendelenburg position (T4-T5).
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Anesthesia and analgesia · Aug 2009
Intraneural injection with low-current stimulation during popliteal sciatic nerve block.
Prevention of an intraneural injection of a local anesthetic during peripheral nerve blockade is considered important to avoid neurologic injury. However, the needle-nerve relationship during low-current electrical nerve localization is not well understood. ⋯ The absence of motor response to nerve stimulation during popliteal sciatic nerve block does not exclude intraneural needle placement and may lead to additional unnecessary attempts at nerve localization. Additionally, low-current stimulation was associated with a high frequency of intraneural needle placement.
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Anesthesia and analgesia · Aug 2009
An expiratory assist during spontaneous breathing can compensate for endotracheal tube resistance.
Although inspiratory assist of spontaneous breathing in intubated patients is common, expiratory assist functions have rarely been reported. Effective expiratory support (ES) could be used to compensate for endotracheal tube (ETT) resistance during spontaneous breathing. In this study, we examined the performance of a new system designed to provide both inspiratory support (IS) and ES during spontaneous breathing with the goal of reducing the effective resistance of the ETT. ⋯ In this study of healthy volunteers, IS plus ES compensated for the airway resistance imposed by a ID 5.0 mm ETT to create pressure changes at the tip of the ETT similar to those of an ID 8.0 mm ETT.