Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2003
Clinical TrialThe effect of epidural neostigmine combined with ropivacaine and sufentanil on neuraxial analgesia during labor.
Spinal neostigmine produces analgesia without respiratory depression or hypotension but provokes major gastrointestinal side effects. Epidural injection of this drug, however, appears to induce analgesia devoid of such side effects. In this study, we evaluated the effect of a bolus of epidural neostigmine on the duration and magnitude of analgesia in early labor and assessed its eventual sparing effect on subsequent local anesthetic requirements. Epidural neostigmine methylsulfate (maximal dose 4 microg/kg) was added to 10 mL of ropivacaine 0.1%, with and without sufentanil 10 microg, to initiate analgesia. Twenty minutes after injection, pain score, sensory level, and motor block were assessed. Time until request for supplemental epidural medication was also recorded. Patient-controlled epidural analgesia with ropivacaine 0.1% was used for epidural supplementation. Maternal and fetal side effects were closely recorded. Neostigmine (4 microg/kg), when added to ropivacaine 10 mg, provided equivalent analgesia to ropivacaine 20 mg but was less effective than sufentanil 10 microg for the initiation of labor epidural analgesia. Further, neostigmine did not modify the subsequent patient-controlled epidural analgesia local anesthetic requirements during labor. No hemodynamic instability, additional motor block, or bothersome side effects were recorded. ⋯ The combination of epidural neostigmine (4 microg/kg) with the local anesthetic ropivacaine, with or without sufentanil, does not significantly enhance neuraxial analgesia during labor. Such a dose, however, has no bothersome side effects.
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Anesthesia and analgesia · Apr 2003
Comparative Study Clinical TrialA comparison of the PAxpress and face mask plus Guedel airway by inexperienced personnel after mannequin-only training.
The PAxpress (PAX) is a new extraglottic airway device consisting of an anatomically curved tube, an inflatable circular cuff in the midsection, a noninflatable gilled conical cuff at the distal end, and an anterior-facing, rectangular hooded vent between the two cuffs. We compared the ability of nurses with no previous airway management experience to ventilate the lungs of 45 ASA physical status I and II anesthetized, paralyzed patients using either the PAX or face mask and Guedel airway (FM/GA) after mannequin-only training. Nurses were asked to ventilate the patient to an expired target tidal volume of 7 mL/kg and then to the maximum tidal volume achievable. The FM/GA was used first and the then the PAX. The target tidal volume was achieved in all patients with both devices. There were no differences in the time taken (PAX, 41 +/- 15 s; FM/GA, 39 +/- 25 s) or the number of insertion attempts to achieve the target tidal volume. There were no differences in the frequency of esophageal leaks at the target (PAX, 9%; FM/GA, 4%) and maximum tidal volume (PAX, 51%; FM/GA, 49%). The maximal tidal volume (1261 +/- 306 versus 958 +/- 220 mL; P < 0.0001) and peak airway pressure (37 +/- 5 versus 28 +/- 6 cm H(2)O; P < 0.0001) was larger for the PAX, but blood was detected more frequently (22% versus 0%; P = 0.001). We conclude that ventilation to a target tidal volume of 7 mL/kg in anesthetized, paralyzed adults is equally successful for the PAX and FM/GA by inexperienced nurses after mannequin-only training. However, the maximal tidal volume and peak airway pressure is larger and airway trauma more common with the PAX. ⋯ Ventilation to a target tidal volume of 7 mL/kg in anesthetized, paralyzed adults is equally successful for the PAxpress (PAX) and Face Mask/Guedel Airway by inexperienced nurses after mannequin-only training. However, the maximal tidal volume and peak airway pressure is larger and airway trauma more common with the PAX.
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Anesthesia and analgesia · Apr 2003
Isoflurane action in spinal cord indirectly depresses cortical activity associated with electrical stimulation of the reticular formation.
Anesthetics act in the spinal cord to ablate both movement and the ascending transmission of nociceptive information. We investigated whether a spinal cord action of isoflurane affected cortical activity as determined by the electroencephalogram desynchronization that occurs after electrical stimulation of the midbrain reticular formation (MRF). Six goats were anesthetized with isoflurane, and neck dissections were performed to permit differential isoflurane delivery to the head and torso. The electroencephalogram was recorded before, during, and after focal electrical stimulation (0.05, 0.1, 0.2, 0.3, and 0.4 mA) in the MRF; in each animal, the brain isoflurane was maintained constant ( approximately 1%). When the torso isoflurane was 0.3% +/- 0.1%, the spectral edge frequency after MRF electrical stimulation (15.3 +/- 1.7 Hz, averaged across all stimulus currents) was more than the spectral edge frequency when the torso isoflurane was 1.2% +/- 0.2% (12.9 +/- 1.0 Hz, averaged across all stimulus currents; P < 0.05). Bispectral index values were similarly affected: 60 +/- 6 when torso isoflurane was low versus 53 +/- 7 at high torso isoflurane (P < 0.05). These results suggest that a spinal depressant action of isoflurane on ascending somatosensory transmission can modulate reticulo-thalamocortical arousal mechanisms, hence possibly reducing anesthetic requirements for unconsciousness and amnesia. ⋯ Isoflurane action in the spinal cord indirectly reduces the cortical activity associated with electrical stimulation of the reticular formation, an effect that might contribute to anesthetic-induced amnesia and unconsciousness.
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Anesthesia and analgesia · Apr 2003
The effect of inhaled colforsin daropate on contractility of fatigued diaphragm in dogs.
We studied the effect of inhaled colforsin daropate, a water-soluble forskolin derivative, on the contractility of fatigued diaphragm in dogs. Animals were divided into 3 groups of 8. In each group, diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20-Hz stimulation applied for 30 min. Immediately after the end of the fatigue-producing period, Group 1 received inhaled vehicle, Group 2 received inhaled colforsin daropate 0.1 mg/mL, and Group 3 received inhaled colforsin daropate 0.2 mg/mL. We assessed diaphragmatic contractility by transdiaphragmatic pressure (Pdi). After fatigue was produced, in each group, Pdi at low-frequency (20-Hz) stimulation decreased from baseline values (P < 0.05), and there was no change in Pdi at high-frequency (100-Hz) stimulation. In Groups 2 and 3, during colforsin daropate inhalation, Pdi at both stimuli increased from fatigued values (P < 0.05). The increase in Pdi was significantly larger in Group 3 than in Group 2. The integrated electrical activity of the diaphragm did not change in any group. We conclude that inhaled colforsin daropate causes an increase in contractility of fatigued canine diaphragm in a dose-related fashion. ⋯ Diaphragmatic fatigue may contribute to the development of respiratory failure. Inhaled colforsin daropate improves, in a dose-dependent manner, the contractility of fatigued diaphragm in dogs.