Der Anaesthesist
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We measured pulmonary elimination of carbon dioxide (VCO2), end-tidal and arterial CO2 tensions (PETCO2, PaCO2), deadspace ventilation (VD/VT), and arterial oxygen tension (PaO2) using a Siemens 930 CO2 analyzer incorporated into a servoventilator and arterial blood gas analyses, respectively, in 31 patients undergoing laparoscopic cholecystectomy with a median duration of pneumoperitoneum (PP) of 60 min. ⋯ During PP, CO2 is reabsorbed from the peritoneal cavity. During the initial unstable phase with rising PaCO2, reabsorption of CO2 is the sum of increased pulmonary elimination of CO2 above baseline and uptake of CO2 into gas stores of the body. We estimated CO2 reabsorption to be on the order of 70 ml/min during the first 30 min of PP. During the later, stable phase, reabsorption of CO2 equals increased pulmonary elimination of CO2 above baseline and was estimated to be in the order of 90 ml/min in 10 patients with 30-75 min of PP (hatched area in Fig. 2). PET-CO2 corresponded well with PaCO2 in these patients. VD/VT and arterial oxygenation did not change significantly with institution or during the course of PP. Monitoring VCO2 probably is a useful aid in the early detection of CO2 emphysema (Fig. 6).
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Cutaneous O2 and CO2 pressures were monitored for 16 h in 55 female patients recovering from major gynaecological surgery performed under neurolept anaesthesia. Postoperative pain was managed either with an antipyretic analgesic (i.m. or i.v. metamizol up to 2.5 g/4 h; group NLA) or with i.v. patient-controlled analgesia using fentanyl (demand dose 34 micrograms, infusion rate 4 micrograms/h, hourly maximum dose 0.25 mg, lock-out time 1 min; group NLA/PCA). In addition, 11 patients received a single i.v. bolus injection of 150 mg amiphenazole, a respiratory stimulant, at the beginning of PCA treatment (group NLA/PCA/AMI). Data were collected and stored by a personal computer, using the TCM3 system with a combination electrode for simultaneous measurement of cutaneous oxygen and carbon dioxide partial pressures (TINA, Radiometer) at 30-s intervals. The overall observation period was four times 240 min; patients from the NLA group who required additional opioids were excluded from the analysis. Means and standard deviations were calculated for individual data and data pooled for 15- or 60-min intervals. Groups were compared by means of the chi-square test, Student's t-test or analysis of variance (level of significance, P < or = 0.05). ⋯ The present study confirmed that spontaneous respiration in the early postoperative period can be monitored non-invasively by measuring cutaneous partial pressures of carbon dioxide and, less precisely owing to wide individual variations, oxygen. It showed that spontaneous respiration is less effective immediately after termination of surgery under neurolept anaesthesia and recovers slowly over the next 4 h. During the first observation period, ventilation was no worse with i.v. PCA using fentanyl than with conventional pain management using the antipyretic analgesic metamizol, confirming the hypothesis that opioid-induced respiratory depression occurs only at overdosage (which is not a problem with individualized dose titration using PCA). Since all patients in the NLA group required additional opioids after the first observation period and had to be excluded from further analysis, it cannot be decided from the present data whether late hypercapnia was due to PCA or to residual effects of surgery and anaesthesia. The respiratory stimulant amiphenazole (150 mg i.v.) was not helpful in improving ventilation; there was no indication of analgesic effects or interactions of amiphenazole.
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Case Reports
[Acute obstruction of an anesthetic gas evacuation system. Ventilation with a Servo Ventilator 900D].
During aorto-coronary bypass surgery acute expiratory airway obstruction occurred in two patients during controlled ventilation with a Servo D ventilator (Siemens Elema) in combination with a Servo EVAC 180 gas evacuation system. In this system expiratory volume passes from the ventilator to the reservoir bag. ⋯ We observed an increase in mean expiratory and inspiratory airway pressure above 40 mmHg due to blockage of the expiratory gas outlet by external lateral dislocation of the valve spring. In conclusion, while free mobility of the valve spring within the hanging Evac bag has to be ascertained at all times for safe application of the EVAC 180 system, the manufacturer should provide some appropriate mechanical shelter around the bag.
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Simulators and training devices are used extensively by educators in 'high-tech' occupations, especially those requiring an understanding of complex systems and co-ordinated psychomotor skills. Because of advances in computer technology, anaesthetised patients can now be realistically simulated. This paper describes several training devices and a simulator currently being employed in the training of anaesthesia personnel at the University of Florida. ⋯ Exercises with the simulator are supported by sessions on a number of training devices. These present theoretical and practical interactive courses on the anaesthesia machine and on monitors. An extensive system, for example, introduces the student to the physics and clinical application of transoesophageal echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)