Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2000
Comparative StudyDefining segments and phases of a time capnogram.
The division of a time capnogram into inspiratory and expiratory segments is arbitrary and results in the inability of a time capnogram to detect rebreathing instantaneously. Demarcation of a time capnogram into inspiratory and expiratory components using gas flow signals will not only facilitate prompt detection of rebreathing, but will also allow application of standardized and physiologically appropriate nomenclature for better understanding and interpretation of time capnograms. A Novametrix((R)) CO(2)-SMO plus respiratory profile monitor (Novametrix Medical Systems, Wallingford, CT) was used to obtain a simultaneous display of CO(2) and respiratory flow waveforms on a computer screen during spontaneous and controlled ventilation using a circle system with the inspiratory valve competent (no rebreathing) and with the valve displaced (rebreathing). Because the response time of the CO(2) analyzer was similar to the response time of the flow sensor, a comparison was made between the two waveforms to determine the inspiratory segment (Phase 0) and the expiratory segment of the time capnogram and its subdivisions (Phases I, II, and III). The end of expiration almost coincides with the downslope of the CO(2) waveform in the capnograms when there is no rebreathing. However, in the presence of rebreathing, the alveolar plateau is prolonged and includes a part of inspiration (Phase 0), in addition to the expiratory alveolar plateau (Phase III). ⋯ Presently, the division of a time capnogram into inspiratory and expiratory segments is arbitrary. Demarcation of a time capnogram into various components using the gas flow signals facilitates prompt detection of the cause of abnormal capnograms that can widen the scope of future clinical applications of time capnography.
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On two occasions, sevoflurane distributed for clinical practice has been found to be contaminated with compounds thought to include hydrogen fluoride (HF) and silicon tetrafluoride (SiF(4)). Both compounds can produce pulmonary injury. However, injury would require fractional distillation of the compounds during the course of sevoflurane vaporization. ⋯ Nuclear magnetic resonance studies indicated that HF interaction with glass changed all HF to three other compounds, one being SiF(4) and the others being unknown. HF and SiF4 distill from sevoflurane more rapidly than sevoflurane is vaporized. Measurement of acidity after sevoflurane administration may not reveal a previous presence of such contaminants.
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Anesthesia and analgesia · Oct 2000
Randomized Controlled Trial Comparative Study Clinical TrialA comparative study with oral nifedipine, intravenous nimodipine, and magnesium sulfate in postoperative analgesia.
We tested the ability of two L-type calcium channel blockers (nifedipine and nimodipine) and the N-methyl D-aspartate natural antagonist magnesium to decrease morphine requirements and pain in the postoperative period in 92 patients undergoing elective colorectal surgery. In a randomized, double-blinded study, patients were assigned to one of four groups. The control group received placebo. The nifedipine group received 60 mg of oral nifedipine. The magnesium group received an initial dose of 30 mg/kg followed by 10 mg x kg(-1) x h(-1) of magnesium sulfate over 20 h. The nimodipine group received 30 microg x kg(-1) x h(-1) of nimodipine over 20 h. Postoperative morphine consumption was assessed for 48 h. Pain at rest and pain on movement were assessed up to the fifth day postsurgery. There were no differences among groups in postoperative morphine consumption at 12 and 24 h. The nifedipine group consumed more morphine than the control and nimodipine groups during 24-48 h. Pain at rest scores were higher at 16 and 24 h in the nifedipine group than in the other three groups. Pain on movement scores were lower at 72 h in the nimodipine group than in the control and nifedipine groups. In conclusion, the perioperative application of oral nifedipine, IV nimodipine, or IV magnesium sulfate failed to decrease postoperative morphine requirements after colorectal surgery. ⋯ The increase of intracellular calcium plays a key role in spinal transmission of pain and in the establishment of central sensitization. We examined the effects of nifedipine, nimodipine, and magnesium sulfate in postoperative analgesia after colorectal surgery. We found no differences in morphine consumption with the administration of each drug alone.
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Anesthesia and analgesia · Oct 2000
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialPercutaneous tracheostomy: ciaglia blue rhino versus the basic ciaglia technique of percutaneous dilational tracheostomy.
Percutaneous dilational tracheostomy (PDT), according to Ciaglia's technique described in 1985, has become the most popular technique for percutaneous tracheostomy and is demonstrably as safe as surgical tracheostomy. In 1999, an extensively modified technique of PDT was introduced, the Ciaglia Blue Rhino (CBR; Cook Critical Care, Bloomington, IL), that consists of one-step dilation by means of a curved dilator with hydrophilic coating. To compare CBR with the basic technique of PDT, we performed a prospective, randomized trial in 50 critically ill adults. Twenty-five of these patients had PDT, and 25 had CBR. Average operating times were <3 min for CBR (range: 50-360 s) and <7 min for PDT (range: 4-20 min; P<0.0001). Tracheostomy was successfully completed in all patients. When CBR was performed, 11 minor, nonlife-threatening complications were noted: nine fractures of tracheal cartilage and two short periods of intraoperative oxygen desaturation. During PDT, seven complications occurred, of which three were potentially life-threatening: two injuries to the posterior tracheal wall, one pneumothorax, two tracheal cartilage fractures (P< 0.05 vs CBR), one case of bleeding, and one short episode of intraoperative oxygen desaturation. Regardless of whether PDT or CBR was performed, oxygenation was not significantly affected, and there was no infection of the tracheostoma. Based on our data, we conclude that new CBR is more practicable than PDT. No life-threatening complications occurred during CBR. ⋯ To assess practicability and safety of the Ciaglia Blue Rhino (Cook Critical Care, Bloomington, IL)-an extensively modified technique of percutaneous dilatational tracheostomy-50 critically ill adults on long-term ventilation underwent either new Ciaglia Blue Rhino or percutaneous dilatational tracheostomy in a prospective, randomized clinical trial.
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Anesthesia and analgesia · Oct 2000
Randomized Controlled Trial Clinical TrialMemantine (a N-methyl-D-aspartate receptor antagonist) in the treatment of neuropathic pain after amputation or surgery: a randomized, double-blinded, cross-over study.
Evidence has accumulated that the N:-methyl-D-aspartate receptor system plays a role in continuous and particularly, in stimulus-evoked pain after nerve injury. We examined, in a randomized, double-blinded, cross-over fashion, the analgesic effect of memantine (a N:-methyl-D-aspartate receptor antagonist) in a group of patients with chronic pain after surgery. We randomized 19 patients to receive either memantine or placebo in the first 5-wk treatment period. A washout period of 4 wks was followed by another 5-wk treatment period with the opposite drug. The dosage of drug was increased from 5 to 20 mg/d. Pain was recorded daily, with the use of a 0-10 numeric rating scale. Before and at the end of each treatment period, pain and sensitivity were also assessed by using the McGill Pain Questionnaire, allodynia to touch, brush and cold, wind-up-like pain, and thresholds to mechanical stimuli (pressure and von Frey hair). A total of 15 patients (12 amputees and three patients with other nerve injuries) completed the study. There was no difference between memantine and placebo on any of the outcome measures. We conclude that memantine at a dosage of 20 mg/d does not reduce spontaneous or evoked pain in patients with nerve injury pain. ⋯ In a randomized, double-blinded and cross-over study, the analgesic effect of memantine (a drug which reduces the excitability of sensitized neurons in the dorsal horn) was examined in 19 patients with chronic pain after nerve injury.