Der Anaesthesist
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In an attempt to develop a noninvasive monitoring technique for patients in the early postoperative period, cutaneous O2 and CO2 pressures (pctO2, pctCO2) were monitored in ten healthy adult volunteers of both sexes (5 male, 5 female, age 29 +/- 5 years, weight 68 +/- 11 kg) who received, in several sessions after a 60-min equilibration period, i.v. bolus doses of fentanyl (3 micrograms/kg and, 60 min later, another 1.5 micrograms/kg), buprenorphine (3 and 1.5 micrograms/kg), naloxone (1.8 and 0.9 micrograms/kg), and the respiratory analeptic amiphenazole (2 and 1 mg/kg) as well as combinations of fentanyl/amiphenazole or buprenorphine/naloxone in the aforementioned dosages. Data were collected and stored by a personal computer using the TCM3 system with a combination electrode for simultaneous measuring of pctO2 and pctCO2 (TINA, Radiometer) at 30-s intervals. The overall observation period was 240 min. Means, standard deviations, and ranges were calculated for individual data and data pooled for 15-min intervals. Groups were compared by means of Student's t-test and analysis of variance. ⋯ As was discussed in detail in a previous communication, monitoring of opiate-induced respiratory depression must be nonstimulant and, preferably, noninvasive. Whereas the precision and/or limitations of monitoring partial oxygen saturations by pulse oximetry is well documented in the literature, knowledge of the value of cutaneous partial pressure monitoring is still limited and controversial for the adult patient population. The present study was performed to define the usefulness of cutaneous blood gas analysis in healthy volunteers receiving opiate dosages well known in recovery room patients. It is concluded that continuous monitoring of pctO2 and pctCO2 can indeed detect opiate-induced respiratory depression in adults. The well-known difference in respiratory pattern for fentanyl and buprenorphine could easily be determined. It was confirmed that naloxone and amiphenazole in the dosage range studied do not influence spontaneous respiration in healthy adults. Thus, the authors are convinced that continuous monitoring of cutaneous partial pressures of oxygen and carbon dioxide is sensitive enough to be used, in combination with pulse oximetry, in a monitoring concept for patients recovering from surgery and anaesthesia. Results in patients undergoing conventional pain management or patient-controlled analgesia with relatively high opiate dosages will be presented in following papers. Concerning the controversy about clinically relevant interactions between fentanyl and amiphenazole or buprenorphine and naloxone, the present study did not confirm any useful antagonism. Whether this is due to limitations of cutaneous monitoring, the difference between volunteers and patients, or pharmacological reasons must be evaluated in further investigations.
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Thiopental is a hypnotic drug that is widely used for the induction of anaesthesia. The mechanism of the short-term action is based on the rapid distribution of the drug, and in contrast to methohexital, the metabolism of thiopental is not relevant in use in conditions of operative anaesthesia. However, in neurotraumatology thiopental is frequently used as continuous infusion for several days to reduce cerebral metabolism. ⋯ The actions of thiopental on global hemodynamics are comparable with the results found in the literature, characterized by a significant reduction in MAP and cardiac output after induction. The hepatic clearance of thiopental found in this study, with an absolute value of 0.21 l/min, is absolutely comparable with the data for total-body clearance reported in the literature. It is concluded that the liver is the only organ responsible for the elimination of thiopental in humans.
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The modified combined plunger pressure and manometer method (KSMM = Kombinierte Stempeldruck-Manometer-Methode) has proved to be a satisfactory alternative to the loss of resistance technique of Dogliotti. The method was tested for practicability and successful identification of the epidural space in 200 patients (80 of them pregnant) by physicians at different stages of their training. It makes it easy for young anaesthetists who are still in training and have not had much experience to learn to identify the epidural space. With this method the experienced operator can make an important contribution to the training of young doctors in epidural anaesthesia without fear of risks and failures.
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Randomized Controlled Trial Comparative Study Clinical Trial
[Micturition disorders following spinal anesthesia of different durations of action (lidocaine 2% versus bupivacaine 0.5%)].
Disturbances of micturition following spinal anaesthesia are considered to be rare and harmless side effects of this technique. For this reason, we set up a prospective study to investigate their incidence, characteristics and intensity. Our special interest was directed at the influence of the duration of action of local anaesthetics. ⋯ Their higher frequency following the longer acting bupivacaine may be evidence of longer lasting blockade of the efferent sacral parasympathetic fibers innervating the detrusor vesicae muscle, leading to inhibition of bladder voiding. The consequences of these disturbances, if not correctly managed, may be distension of the urinary bladder with ensuing infection and loss of tone of the detrusor muscle. Various measures are recommended: choice of the longer acting local anaesthetic only if necessary, careful control of bladder filling, restrictive infusion of fluids, early mobilization, carbachol, catheterization in good time, prophylactic placement of an indwelling catheter in patients with previous disturbances.
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Randomized Controlled Trial Comparative Study Clinical Trial
[Does an injection filter modify the cranial spread of a sensory blockade in epidural anesthesia?].
In a prospective study we compared the spread of sensory blockade in epidural anaesthesia with and without Micropore filter. ⋯ A total of 32 patients undergoing varicose vein stripping under epidural anaesthesia were randomly assigned to two groups of 16 each. Bupivacaine 0.75% and POR 8 (0.1 IU/ml) were administered by means of a constant-velocity perfusor. In group A a Micropore filter was inserted between the perfusor syringe and the epidural catheter. In group B the epidural catheter was connected to the syringe without the filter. The puncture was performed at the L3-4 interspace with the patient in a sitting position. An epidural catheter was advanced 3 cm cephalad. Using the pin-prick method, the sensory level of the blockade was tested 5, 7, 10, 15, 20 and 30 min after injection of the local anesthetic solution. Statistical evaluation was performed with the t-test for unpaired samples. RESULTS. After 10 min the spread of analgesia was 5.75 +/- 1.26 segments in group A and 8 +/- 1.89 segments in group B; after 15 min it was 7.06 +/- 1.62 segments and 9.56 +/- 1.54 segments; after 20 min, 7.87 +/- 1.62 segments and 10.62 +/- 1.45 segments; and after 30 min 8.12 +/- 1.66 segments and 11.12 +/- 1.45 segments in group A and B, respectively. At any time sensory blockade was higher in group B (without Micropore filters) than in group A. The mean difference between the two groups amounted to 2-3 segments. The differences were significant at any time (P less than 0.001). These results show that the use of a Micropore filter in epidural anaesthesia leads to a reduced spread of sensory blockade. In our own examinations we found lowering of the pressure of the local anaesthetic solution that passes through the Micropore filter compared with the pressure of the solution injected without the filter. This seems to be the reason for the reduced spread of sensory blockade. Using these filters the onset of analgesia is delayed, and a given spread of analgesia needs a larger dose of local anaesthetic and is thus accompanied by a higher toxicity.