PubMed · 10594443
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T Palit, W Butt. 2000. Target-controlled infusions.. https://doi.org/10.1046/j.1365-2044.2000.01242.x
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The performance of a modified target-controlled infusion system was investigated in 16 dogs undergoing routine dental work, by comparing the predicted concentrations of propofol in venous blood samples with direct measurements; the optimum targets for the induction and maintenance of anaesthesia were also identified. The performance of a target-controlled infusion system is considered clinically acceptable when the median prediction error, a measure of bias, is not greater than +/-10 to 20 per cent, and the median absolute performance error, a measure of the accuracy, is not greater than 20 to 30 per cent. The results fell within these limits indicating that the system performed adequately. The optimal induction target was 3 microg/ml, and anaesthesia of adequate depth and satisfactory quality was achieved with maintenance targets of between 2.5 and 4.7 microg/ml propofol. The system was easy to use and the quality of anaesthesia was adequate for dental work.
PURPOSE: Extracranial radiosurgery requires control of organ motion. The purpose of this study is to quantitatively determine the extent of liver motion in anesthetized dogs with continuous i.v. propofol infusion with or without muscle relaxants and high-frequency jet ventilation. METHODS AND MATERIALS: Five dogs were used in the experiment. Each dog was restrained while anesthetized in the supine position using an alpha cradle. Surgical metal clips were implanted around the liver periphery so that its motion could be visualized using a fluoroscopic imaging device in a conventional simulator. Initially, two orthogonal simulation films were taken to correlate locations of implanted clips. Two orthogonal views of fluoroscopic images for each anesthetized dog were recorded on a magnetic tape and analyzed from the post-imaging data. Liver motion was documented under the following three conditions: 1) ventilated with a conventional mechanical ventilator, 2) ventilated with a high-frequency jet ventilator, and 3) ventilated with a high-frequency jet ventilator and total muscle paralysis (with vecuronium injection). The maximum liver motion for each dog was analyzed in three orthogonal directions: the inferior-to-superior direction, the anterior-to-posterior direction, and the right-to-left direction. RESULTS: When the anesthetized dogs were ventilated with a conventional mechanical ventilator, the average liver motions were 1.2 cm in the inferior-to-superior direction, 0.4 cm in the anterior-to-posterior direction, and 0.2 cm in the right-to-left direction, respectively. After the introduction of high-frequency jet ventilation, the average liver motions were reduced to 0.2 cm in the inferior-to-superior direction, 0.2 cm in the anterior-to-posterior direction, and 0.1 cm in the right-to-left direction. The maximum liver motion was dependent on ventilator settings. There was no additional measurable motion reduction with the addition of the muscle relaxant. CONCLUSION: The liver motion in each anesthetized dog was controlled under 3.0 mm in all directions with the use of high-frequency jet ventilation. No detectable advantage was identified by the injection of muscle relaxant in terms of further reducing the liver motion. The preclinical animal study indicated that the use of high-frequency jet ventilation (HFJV) would be able to limit the liver motion to an extent acceptable for the application of extracranial radiosurgery in humans. Radiosurgery for localized liver tumors warrants further investigation.
In this study we compared operating room (OR) efficiency of total intravenous anaesthesia (TIVA) with remifentanil and propofol and balanced anaesthesia (BAL) with fentanyl and isoflurane in cataract surgery using computersimulation. We simulated patient flow for one OR and for three ORs. Time intervals of patient flow were randomly generated from the results of a prospective, randomized trial. Both for one and for three ORs, the postanaesthesia care unit (PACU) finished earlier and one additional case per OR and per day could be performed when TIVA was used for the procedures. Overtime in the PACU was less after TIVA. With a workload of 13 or 15 operations per day in three ORs, monitoring equipment for an additional patient in the PACU was required when BAL was used. TIVA with remifentanil and propofol was associated with more OR efficiency than balanced anaesthesia with fentanyl and isoflurane when given for cataract surgery.