Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1978
Correlation of oxygen uptake and cardiovascular dynamics during N2O-fentanyl and N2O-thiopental anesthesia in the dog.
The relationship between changes in wholebody O2 consumption (VO2) and cardiovascular dynamics during changing levels of N2O-fentanyl and N2O-thiopental anesthesia was determined in 24 dogs. Dose-dependent reductions in VO2, mean blood pressure, and cardiac output occurred with infusion of fentanyl and thiopental. Painful stimuli increased VO2 during light anesthesia but not during deeper levels of anesthesia. Deep levels of N2O-fentanyl and N2O-thiopental anesthesia may protect the patient with limited cardiac reserve by reducing VO2 and preventing increases in VO2 caused by painful stimuli.
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Anesthesia and analgesia · Jan 1978
Tetanic fade and post-tetanic tension in the absence of neuromuscular blocking agents in anesthetized man.
Frequency and time dependent changes in neuromuscular transmission were examined in 30 patients undergoing elective minor surgical procedures not requiring the use of muscle relaxants. Anesthesia was induced with sodium thiopenthal and maintained with N2O-O2 and fractional does of meperidine or fentanyl. Neuromuscular function was measured by recording the force of thumb adduction evoked by supramaximal stimulation of the ulnar nerve at the wrist. ⋯ From analysis of present data, criteria for normal responses to 10-second tetanic trains of varying frequencies were established. At a frequency of 30 Hz, the tetanic response is fully maintained and followed by post-tetanic potentiation; at a frequency of 50 Hz, both tetanic and post-tetanic responses are maintained; at a frequency of 100 Hz, there is tetanic fade, followed by a post-tetanic depression of the single indirect twitch responses. It is concluded that frequency and duration of indirect stimulation are the most important factors in using tetanic maintenance and post-tetanic events in assessment of recovery from neuromuscular block.
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Anesthesia and analgesia · Jan 1978
A new nerve stimulator for monitoring neuromuscular blockade and performing nerve blocks.
A new stimulator is described with characteristics designed to take advantage of recent knowledge of the pharmacology of neuromuscular relaxants and events involved in normal neuromuscular transmission. The stimulator has proven as useful in performance of peripheral nerve blocks as in monitoring neuromuscular blockade.
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Bupivacaine (Marcaine) hydrochloride, a long-acting local anesthetic drug, was used in concentrations of 0.25, 0.5, or 0.75 percent with and without a vasoconstrictor, in amounts ranging from 25 to over 600 mg, for caudal, epidural (peridural), or peripheral nerve block for 11,080 surgical, obstetrical, diagnostic, or therapeutic procedures. Onset of anesthesia occurred in 4 to 10 minutes and maximum anesthesia in 15 to 35 minutes. Concentrations of 0.25, 0.5, and 0.75 percent consistently produced complete sensory anesthesia of the integumentary and musculoskeletal systems. ⋯ In intra-abdominal surgery, only 0.75 percent consistently produced profound muscle relaxation. Fifteen systemic toxic reactions occurred, but no untoward sequelae resulted from them. One inadvertent subarachnoid injection of 110 mg resulted in a total spinal block with an uneventful recovery.