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A new anesthesia machine incorporates a "coasting mode", but the extent to which a coasting technique can maintain anesthesia at the end of a procedure under optimal conditions (closed circuit anesthesia) remains unknown. Sixty-nine patients undergoing peripheral or abdominal surgery were assigned to 1 of 9 groups, depending on when desflurane coasting (in O2/air) was started (after 4, 9, 16, 25, 36, 49, 64, 81, or 100 min). The end-expired desflurane concentration was maintained at 4.5% in O2/air prior to coasting with a conventional anesthesia machine. After initiating coasting (using a closed-circuit technique), we examined when the end-expired desflurane concentration reached 70, 60, 50, and 40% of its value during maintenance (= 30, 40, 50 and 60% decrement times, respectively). Decrement times increased with increasing duration of anesthesia, and varied widely. After 64 min of maintenance anesthesia, the end-expired desflurane concentration remained at or above 70, 60, 50, and 40% of its maintenance value during 10.3 +/- 2.3, 16.0 +/- 3.5, 25.0 +/- 5.9, and 45.4 +/- 19.3 min, respectively (average +/- standard deviation). Coasting can briefly maintain anesthesia towards the end of a procedure. While savings with an automated coasting mode are likely to be modest per patient, they may become substantial when multiplied by the number of procedures per day per operating room with no increase in the clinical workload of the anesthesia provider.

Up to eighty percent of all patients admitted to hospital worldwide will receive a peripheral IV and this procedure is now considered indispensable to human health. However, despite its global use, the choice of catheter is not always governed by clear and universal guidelines. After reviewing the few best-practice recommendations which exist, we propose a patient--and therapy--driven matrix for deciding on the gauge and length of peripheral catheter for the individual patient. This matrix takes patient age, clinical stability, current state of veins, therapy duration and the nature of the medication to be delivered into consideration. Use of such a matrix will not deliver a formulaic answer but will orient choices along logical, evidence-based lines. This approach will be an advance on the all-too-common reliance on habit and tradition in the choice of peripheral IV catheter.

Interventional Neuroradiology is a rather young department, that asks for an appropriate anesthesia management. This article highlights mainly the practical approach, with special directions for a thorough premedication, monitoring and patient positioning and extra attention to heparinisation and allergic reactions. Different anesthetic techniques are dealt with, namely conscious sedation and general anesthesia, as well as directives concerning potential complications.

Contemporary multigas analyzers determine anesthetic gas concentrations using (near) infrared analysis at either 3.3 or 8-9 microns. Methane also absorbs infrared light at 3.3 microns, but not at 8-9 microns. Consequently, erroneous anesthetic agent readings may result when methane is present in the circuit (e.g. during closed circuit anesthesia), potentially compromising patient safety. We have analyzed in laboratory conditions the influence of different known methane concentrations (100, 500 and 1000 ppm) on the gas-analysis readings provided by some clinical monitoring devices that use infrared absorption for the measurement of inhalation anesthetic concentration. At 3.3 microns wavelength the influence on the measurement of halothane was important, whereas the influence on that of enflurane and isoflurane was less pronounced. For desflurane and sevoflurane measurements, the influence of methane at 3.3 microns wavelength proved to be minimal. At higher wavelengths (8-9 microns) no influence of methane could be demonstrated.

With rocuronium optimal intubating conditions are earlier achieved than the adductor pollicis muscle onset time. Using the transition time we defined a better parameter for clinical relaxation. The onset of relaxation was determined in 20 patients. After a stable response was achieved with a 0.1 Hz single twitch stimulation 0.60 mg/kg rocuronium was injected. The three different stades during the onset of relaxation were determined. These are the lag time, transition time (transition between second and third phase) and onset time. Whether the transiton time corresponds with optimal intubating conditions was evaluated in 40 other patients. The median transition time was 67.4 (P25:52.5, P75:76.3) seconds with a corresponding relaxation of 76.2 (P25:81.4, P75:70.7)%. The intubating conditions were significantly better at a relaxation level corresponding with the transition time. We conclude that the transition time approximates the intubating time and corresponds with fair intubating conditions. This parameter can be preferred to define the moment with optimal intubating conditions.

Efficacy and safety of a PCA protocol, without loading dose or background infusion, was investigated in 40 consenting patients after osteotomy of the foot. All patients had intrathecal lidocaine 5% 1.8 ml preoperatively. Postoperative pain relief was provided with morphine from a Baxter Travenol infusor with PC module. The morphine concentration was 2 mg/ml or 3 mg/ml. In order to reach the analgesic blood concentration as quickly as possible, the patients were instructed to start PCA from the very first moment pain occurred. The patients breathed room air. The nursing staff evaluated respiratory and cardiovascular parameters, pain and side effects. Although mean VAS scores were higher than 3 in the early postoperative phase, no supplementary analgesics were required. One patient had urine retention. One patient had a drop in blood pressure at the start of morphine, which was quickly restored with the administration of colloids. Oxygen saturations were lower (SpO2 < 95%) the first hours postoperatively, especially at the first assessment where no morphine was administered. Pain or relative hypovolaemia could be an explanation. Dry mouth and sleepiness were the most frequently reported side-effects, followed by dizziness, vomiting and nausea. Sweating and itching were less frequently reported. The occurrence of the side effects was the highest during the first postoperative day. We conclude that even when morphine is used in PCA without loading dose or background infusion after opiate-free locoregional analgesia, close monitoring is necessary for at least 5 hours.

The Datex Relaxograph is a neuromuscular transmission monitor, which measures the degree of neuromuscular blockade during anesthesia. In order to evaluate the reliability of the Relaxograph, results, obtained with this apparatus, were compared with simultaneous mechanical measurements obtained with the Myograph 2000 (Biometer). Although there was a good correlation between the two throughout the study, a shift towards mechanical responses was observed in all cases. Subsequently, the Relaxograph was used to evaluate atracurium and vecuronium when given accordingly to the priming principle. Results show that neither drug offers major clinical advantages over the other. In a third study, a new bolus-constant infusion regimen of atracurium was evaluated. Results show that it produces a predictable and stable neuromuscular blockade.

Midazolam is a recently introduced benzodiazepine with a half life of 1-4 hours. Midazolam (0.15 mg/kg) has been compared with diazepam (0.2 mg/kg) for sedation during locoregional anesthesia in 60 premedicated patients. No difference among the two groups for heart rate, bloodpressure, respiratory rate and incidence, and duration of apnoea was noticed after an i.v. bolus administration. The recovery time was equal in both groups. Midazolam was significantly less painful at injection. The sedation pattern between both groups is only different at 60 minutes, where more better sedated patients are seen in the midazolam group. Except the pain at injection and a better sedation pattern after 60 min. the differences in the other parameters are only borderline.

Dissatisfaction with the results of conventional respiratory support has led to the use of high-frequency jet ventilation in desperate clinical situations with severe acute respiratory failure. We report a case of a 77 year old man with bilateral bronchopleural fistulae, who was ventilated with a combination of intermittent positive pressure ventilation and high-frequency jet ventilation. The hemodynamic and respiratory advances of this combination are discussed in an overview of the literature.

Vecuronium (V) and atracurium (A) were compared in a randomised study in premedicated patients undergoing laparoscopy for gynecological pathology. Both groups contained ten patients. Anesthesia was induced with fentanyl (0.1 mg) and thiopentone (1 mg/kg initially and subsequently 4 mg/kg). A priming dose of vecuronium (20 micrograms/kg) or atracurium (100 micrograms/kg) was given one minute before the intubating dose (60 micrograms/kg for vecuronium and 300 micrograms/kg for atracurium). Ninety seconds thereafter intubation was performed. Maintenance of anesthesia consisted of isoflurane at an inspiratory concentration of 1% in a mixture of O2/N2O (50%/50%) with small supplements of fentanyl. Neuromuscular block was monitored with the Datex Relaxograph. Results show that neither drug offers major clinical advantages over the other: there is no difference in speed of onset (V:T190sec 14.6 +/- 4.3%; A:T190sec 23.5 +/- 6.5%; Mean +/- SEM) and duration of neuromuscular block (V:T150sec 34.2 +/- 3.5 min; A:T150sec 41.3 +/- 2.8 min; Mean +/- SEM) and intubation conditions are almost identical.

Noncompartmental pharmacokinetic methods using the statistical moment theory can be very helpful in comparing the mean residence time of drugs in the body. These methods are based on the estimation of the area under the time versus plasma concentration curve after a single intravenous drug bolus, and can also be used to estimate clearance, effective half life and the apparent volume of distribution of the drug. In the group of nondepolarising neuromuscular blocking drugs, atracurium offers the advantage of having the smallest mean residence time.