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Description / Table of Contents: Abstract. The laryngeal mask (LM) was developed by A. Brain to overcome the disadvantages of the face mask (impractical) and the tracheal tube (invasive). Today this new instrument is applied on a broad scale in Great Britain and with growing interest in continental Europe. The laryngeal mask comes in five sizes to fit different age groups. The blindly applied technique of positioning the LM can be easily learned. Spontaneous or artificial ventilation is possible if the LM is in the correct position. Mechanical ventilation may lead to the insufflation of air into the stomach. Therefore, ventilatory peak pressure should not exceed 20 – 25 cm H2O and ventilation must be closely monitored. The risk of aspiration can be avoided by the proper selection of patients. The LM may be used with different anaesthetic techniques; muscle relaxant drugs are not mandatory. The authors have applied this mask more than 3000 times, and this new instrument obviously has potential for different clinical indications. The LM may be applied for short surgical interventions in all age groups except premature infants. Complications such as regurgitation, aspiration and laryngospasm can be avoided by the awareness of the anaesthetist and by an adjusted deep plane of anaesthesia. Apart from anaesthesia, the LM can be used for bronchoscopy in children, for difficult intubations and as a preliminary airway in cases of resuscitation. Two studies performed in Great Britain have evaluated the LM for resuscitation. The investigations should be confirmed in German-speaking countries.

Description / Table of Contents: Abstract Objective: The data of 60 postoperatively sedated and ventilated patients were studied for analysis of oesophageal, bladder, and rectal temperatures. The purpose of the investigation was to clarify whether changes of oesophageal temperature are adequately reflected by bladder and rectal temperatures and whether the rate of rewarming has an influence on the accuracy of the latter two sites. Methods: For temperature recording, a Hi-Lo Temp® esophageal stethoscope (Mallinckrodt Medical), a Foley FC400-18 catheter temperature sensor (Respiratory Support Products, Mallinckrodt Medical), and a rectal temperature probe N401 (YSI) were used. Each probe and matching recording unit was calibrated over a range of 30–40 °C against a reference quartz thermometer (Hewlett packard Model 2801 A) in a thermostated water bath before the investigation. Five measuring points distributed over the whole period of rewarming were evaluated. Patients were assigned to groups with slow and fast rewarming, respectively. Agreement between the methods of measurement was assessed as described by Bland and Altman. Furthermore, differences between the oesophageal and bladder or rectal temperature were checked at each measuring point for statistical significance using the t-test. Results: In regard to oesophageal temperature, the bladder and rectal temperatures had biases of –0.01 °C and –0.03 °C, respectively. Limits of agreement (±2 s) were ±0.68 °C and ±0.82 °C, respectively. The bias of the bladder temperature was independent of the rate of rewarming (Fig. 3). The bias of the rectal temperature, however, differed in regard to the rewarming rate, being +0.06 °C in the group with slow rewarming and –0.13 °C in the group with fast rewarming (Tables 1 and 2, Fig. 1 and 2). These differences were significant for the measuring points 4 and 5 (Fig. 4). Conclusions: Bladder and rectal temperatures can accurately indicate the oesophageal temperature with a very small bias in postoperatively sedated and ventilated patients. Since the rate of rewarming influences the accuracy of rectal temperature readings, monitoring of bladder temperature seems to be more favourable in the postoperative period.

Description / Table of Contents: Abstract We report a complication during the insertion time of a central venous catheter in a patient with intracerebral bleeding. This complication was caused by an inadvertent dislocation of a subclavian catheter. Hydromediastinum and bilateral hydrothorax developed. There was a clear diagnosis followed by removal of the central venous catheter after radiological investigations could explain the cause of the complication and the clinical symptoms. In the course of events mediastinitis was diagnosed. The clinical condition improved under antibiotic therapy. The patient could be transferred to another clinical unit for endovascular treatment of an arterio-venous cerebral malformation.

Description / Table of Contents: Abstract Neoplastic or traumatic lesions of the brain stem or the upper spinal cord frequently cause respiratory insufficiency necessitating permanent mechanical ventilation. If the integrity of the diaphragm and its nerves is not affected, adequate ventilation can be achieved by electric stimulation of the phrenic nerves [1, 3, 5, 6]. Diaphragm pacing systems mean the patients can be independent of ventilator treatment. This is a psychological advantage for the patient, giving him or her the option of living in less specialized medical care units and perhaps even at home [4, 9]. Case report. We report the case of a 47-year-old man with a brain stem tumour, which was resected in large pieces. During the postoperative period an increasingly severe respiratory insufficiency developed, which finally made continuous mechanical ventilation necessary. After the viability of the phrenic nerves and contractility of the diaphragm had been shown by direct stimulation of the nerves to be still intact, it was decided that a diaphragm pacer system should be implanted. A “Diaphragm Pacer System S232 G” (Avery Laboratories, Glen Cove, N.Y., USA: external transmitter, antenna, implanted electrode and receiver) was implanted. Using a supraclavicular approach, phrenic nerve electrodes were placed around each nerve and connected with subcutaneous implants of radio signal receivers. Six days after implantation phrenic nerves were stimulated for a first short period. External antenna loops were taped to the skin over the implanted receiver sites (Fig. 3). The impulses produced by the transmitter were delivered via these antenna loops and led to contraction of the diaphragm, providing almost normal respiration. The duration of stimulation was increased stepwise from 1 h a day to full-time stimulation. Three weeks after implantation of the diaphragm pacer system the patient could be totally weaned from mechanical ventilation. After a further 2 weeks it was possible to discharge him from the intensive care unit, and he was then transferred to a rehabilitation centre.

Description / Table of Contents: Abstract 100 ASA I and II children, aged 4 to 14 years, and scheduled for strabismus surgery, were randomly assigned to one of the following groups: group 1 (n=50): endotracheal tube, group 2 (n=50): laryngeal mask airway. Apart from airway management, the anaesthesiological procedures were identical in both groups: induction with 2–3 mg/kg propofol, 0.02 mg/kg alfentanil, 0.05 mg/kg vecuronium, and 0.01 mg/kg atropine. After endotracheal intubation or insertion of the laryngeal mask, anaesthesia was continued with 6–15 mg/kg·h propofol and 10–30 μg/kg·h alfentanil. All patients were ventilated with N2O/O2 (2:1). No antiemetics were given, gastric contents were not aspirated. Postoperative nausea and vomiting (PONV) were recorded by 24 h, the incidence of sore throats was recorded 8, 12, and 24 h post-operatively. Results. The incidence of PONV was higher in group 1 (vomiting 48% vs 32%), nausea 28% vs 16% n.s.). Group 1 children had a higher incidence of sore throats (20% vs. 12%, n.s.), of a “lump in the throat” (10% vs 4%, n.s.), hoarseness (24% vs 0%, p〈0.001) and dysarthria (10% vs 4%, n.s.). Conclusions. In children undergoing strabismus surgery, the laryngeal mask airway was superior to the endotracheal tube in terms of PONV and was associated with fewer local complications such as sore throat.

Description / Table of Contents: Abstract The number of patients with congenital cyanotic heart disease who reach child-bearing age is increasing. This is partly a consquence of the high long-term survival and the haemodynamic benefits resulting from the Fontan procedure, which is used for the definitive palliation of such cyanotic heart disease as tricuspid atresia and single ventricle. However, so far little experience has been recorded with pregnant patients who have undergone right ventricular exclusion procedures. The particular physiology of a univentricular heart and a passive, non-pulsatile blood flow through the lungs has significant implications for the anaesthetic obstetric management of these patients. We report a case of successful pregnancy and caesarean delivery after a modified Fontan procedure. Case report. The patient was a 30-year-old pregnant woman with a singleton pregnancy. At the age of 20, after four palliative shunt operations, she had undergone a modified Fontan operation due to tricuspid atresia with a single ventricle, d-transposition of the great arteries, pulmonary atresia and a single atrium. Following the Fontan repair, she initially suffered from intermittent Wolff-Parkinson-White syndrome and isorhythmic AV dissociation. The pregnancy was uneventful, and caesarean section was scheduled for 32 weeks' gestation. Because of the increased risk of thrombosis, the patient was treated with s.c. heparin preoperatively; for this reason, epidural anaesthesia was excluded, though it may otherwise be preferred for such patients. Amoxicilline was used to prevent endocarditis. At the date of caesarean delivery her body weight was 54 kg and boy height, 155 cm. Before induction of anaesthesia, a central venous and a radial artery catheter were placed for invasive pressure monitoring. An exaggerated left lateral tilt position was used to avoid aortocaval compression. After careful preoxygenation, anaesthesia was induced with 24 mg etomidate, 1.5 mg norcuronium, and 75 mg succinylcholine. Halothane 0.5–0.7% in oxygen was used during the first few minutes of surgery. Central venous pressure under mechanical ventilation was 20 mmHg, while the heart rate varied between 70 and 90 bpm. Delivery was accomplished 8 min after the induction of anaesthesia. The Apgar scores after 1 and 5 min were 9 and 10, respectively. Anaesthesia was continued with fentanyl, midazolam and nitrous oxide 50%. The remainder of surgery was unevenful. The child is now 5 years old and healthy. The mother has a near-normal activity level and does not need any help to care for her child. Discussion. After a modified Fontan repair, i.e. atriopulmonary or total cavopulmonary anastomosis, the pulsatile pulmonary blood flow is converted to a passive, non-pulsatile blood flow that depends critically both on the pressure gradient between right (RAP) and left atrial pressure (LAP) and on pulmonary vascular resistance (PVR). Thus, the maintenance of an adequate transpulmonary pressure gradient and avoidance of an increase in PVR are of major importance for the obstetric anaesthetic management in patients who have undergone right ventricular exclusion procedures. Impairment of venous return caused by slight caval compression or high airway pressure may reduce cardiac output more critically than in patients with a normal circulation. Conclusion. This case demonstrates that the haemodynamic consequences of pregnancy and of caesarean delivery under general anaesthesia can be tolerated in post-Fontan patients despite the absence of a contractile pulmonary ventricle.

Description / Table of Contents: Abstract The volatile agent sevoflurane enables a rapid emergence from anaesthesia. The aim of this study was to investigate the possibility of increasing turnover in pediatric anaesthetic cases by use of sevofluran in comparison with halothane. Often short cases or day cases need rapid turnover. Methods and patients: The pediatric patients aged 4–14 years (ASA I) presenting for elective ophthalmic surgery were randomised to either the halothane or the sevoflurane group. Standard monitoring was applied to all patients, in addition the pEEG was used to determine comparable anaesthetic depth. Sevoflurane or halothane were titrated to a SEF 90 of 8–12 Hz. Management of the airway was done with the RLMA (reinforced laryngeal mask). All patients were under controlled ventilation. At the end of surgery and anaesthesia 3 time intervals were measured: phase I) end of anaesthetic application – start of spontaneous respiration; phase II) start of spontaneous respiration – removal of RLMA. The SEF 90 interval was also assessed. Results: 18 cases were included (halo n=8/sevo n=10, no significant differences concerning weight, age, anaesthesia time). There is a significant advantage for the Sevoflurane group in phase II of 6.8 minutes. No differences were seen in phase I and SEF 90 interval. Conclusion: Sevoflurane offers the potential for shortening turnover in pediatric anaesthesia.

Description / Table of Contents: Abstract. Hypothermia (Tcore〈36 °C) can be observed in 60% – 80% of all admissions to the post-anaesthetic recovery unit. Effective warming devices may accelerate rewarming, improve patient comfort, and suppress shivering thermogenesis. This study was designed to compare the efficiency of warming devices in extubated postoperative patients and their effect on postoperative oxygen uptake (V˙O2). Methods. Thirty-five ASA I and II patients after laparoscopic hernioplastic repair with core temperatures 〈36 °C were randomly assigned to either postoperative nursing under a radiant heater (group R, n=11, Aragona Thermal Ceilings CTC X, Aragona Medical AB, Täby, Sweden), a forced air system (group L, n=12, Bair Hugger, Augustine Medical Inc., Eden Prairie, Minnesota, USA), or a normal cotton hospital blanket (group K, n=12). Anaesthesia was conducted totally intravenously with propofol, alfentanil, and vecuronium. Mean body temperature and total body heat were calculated from urinary bladder temperature and four subcutaneous temperature measurements. The rate of thermogenesis was calculated from continuous measurement of V˙O2 (Datex Deltatrac Metabolic Monitor, Datex Instrumentarium Corp., Helsinki, Finland). Heat balance was derived from the increase in total body heat minus body heat production. Heart rate and noninvasive blood pressure were measured by the Cardiocap (Datex Instrumentarium Corp., Helsinki, Finland). All data were transferred to an IBM-compatible computer at 60-s intervals. Measurements were stopped when core temperature reached 37 °C. The rate of change was calculated for each variable for the period 15 min after the beginning of rewarming to attainment of 37 °C. Data are presented as median, minima, and maxima (min↔max); the Mann-Whitney U test was used to test for significance of group differences. Results. All groups were comparable for body weight, height, age, and amount of postoperative infusions. Temperatures at admission were 35.2 (33.4↔35.9), 34.7 (34.3↔35.8), and 35.4 (34.3↔35.9) °C for groups R, B, and K, respectively. No significant differences in the rate of central rewarming could be found for these groups with 0.81 (0.41↔1.32), 0.76 (0.40↔1.07), and 0.70 (0.37↔1.13) °C/h (Fig. 1). The mean V˙O2 of 3.41 (3.07↔3.73), 3.55 (2.78↔4.06), and 3.79 (2.51↔7.00) ml/kg/min also did not differ significantly (Fig. 3). Significant differences between groups R and B [4.39 (3.74↔6.19) and 4.30 (3.46↔6.67) ml/kg/min] and K [5.92 (3.79↔10.64) ml/kg/min] were found for V˙O2 maxima during the course of investigation (Fig. 4). The heat balance revealed significant differences among treatment and control groups with −88 (−266↔+30), −41 (−212↔+12), and −191 (−265↔−86) kJ/h for groups R, B, and K. We additionally calculated the heat balance as a quotient, which showed 0.70 (0.22↔1.07), 0.86 (0.44↔1.04), and 0.49 (0.31↔0.79) for groups R, B, and K (Fig. 4). The mean rate-pressure product of all groups did not differ significantly during the period of investigation. Conclusions. Neither external heat supply by radiant heat nor by a forced warm air system significantly reduced rewarming time in extubated, awake patients. As measured by heat balance, both active treatments saved about 20% more body heat production than in the control group. Continuing peripheral vasoconstriction may be the reason for the low efficiency of heat transfer. Thermal treatment did reduce the peak load (max. V˙O2) on the oxygen transport systems, though shivering was treated by pethidine if it occurred. External rewarming did not reduce the average load (mean V˙O2). Thus, concerning the goal of accelerating rewarming, it appears more rational to prevent intraoperative heat loss. For a comparison of efficiency of different warming devices, postoperative extubated patients do not appear to be an ideal model for study.

Description / Table of Contents: Abstract Strabismus surgery in children is associated with a high incidence of postoperative nausea and vomiting (PONV). Methods. Ninety ASA class I and II children aged 6 to 16 years and scheduled for strabismus surgery were randomly assigned to one of the following groups: Group 1 (n=30): thiopentone 4–6 mg/kg i.v., halothane 0.8–1.5%, N2O―O2 2:1, no opioids, droperidol 75 μg/kg i.v.; Group 2 (n=30): propofol 2–3 mg/kg i.v., propofol 6–9 mg/kg·h, alfentanil 30 μg/kg·h, N2O-O2 2:1, no antiemetics; Group 3 (n=30): similar to group 2, but ventilation with air and O2 2:1. All patients were mechanically ventilated during anaesthesia and gastric contents were aspirated. Recovery scores were calculated for 2 h, emetic scores for 24 h postoperatively. Results. Emetic episodes during the first 24 h were recorded in 40% of group 1, 26.7% of group 2, and 40% of group 3 patients. The oculocardiac reflex occurred only in groups 2 and 3, but not in group 1 children. Recovery scores were significantly higher in groups 2 and 3 compared to group 1. Conclusions. In children undergoing strabismus surgery propofol/alfentanil anaesthesia without antiemetics may be equal or even superior to thiopentone/halothane anaesthesia combined with droperidol in terms of PONV and recovery from anaesthesia.

Description / Table of Contents: Abstract Heat loses during surgery occur mainly to the environment and due to infusions and irrigations. Infusions given at room temperature account for a great deal of the total heat deficit during major operations, e.g., the infusion of 53 ml/kg 20° C fluid leads to a loss of 1° C in mean body temperature. Hence, heating i.v. fluids will add to the effect of other measures aimed at reducing heat loss to the environment. We investigated the efficacy of different warming methods for i.v. fluids in an experimental model by measuring the temperature at the end of the delivery line. Methods. The following in-line warmers were studied: Hotline HL-90 and System H-250/heat exchanger D-50 (Level 1 Technologies, Marshfield, USA), Astotherm IFT 260 (Stihler Elektronic GmbH, Stuttgart, Germany), RSLB 30 H Gamida (Productions Hospitalieres Francaises, Eaubonne, France), Bair Hugger 241/Modell 500 Prototype (Augustine Medical, Eden Prairie, USA). They were compared with prewarming infusions (39° C) only using the Clinitherm S (Labor Technik Barkey GmbH, Bielefeld, Germany) and prewarming with “active insulation” of the delivery line using the Autotherm/Autoline system (Labor Technik Barkey GmbH, Bielefeld, Germany). We investigated the influence of four variables on the efficacy of warming: (1) flow rate (50–15,000 ml/h); (2) ambient temperature (20° C and 25° C); (3) infusion bag temperature (6° C, 20° C, and 39° C); and (4) length of infusion system downstream from the heat exchanger. Fluid temperatures were measured using thermistors of 1 mm diameter (Modell YSI 520, Yellow Springs Instruments Co., Yellow Springs, USA) incorporated into 3-way stopcocks. Temperatures were recorded using Hellige temperature monitors (Hellige GmbH, Freiburg im Breisgau, Germany) and the signals were collected at 10 Hz through an AD converter and averaged over 1 min. Flows were calculated by timed collection into calibrated cylinders; 10 to 12 different flow rates were taken to define one temperature/flow plot. Effective warming was defined as a temperature 〉33° C at the end of the infusion line. Results. At high flow rates (〉2,500 ml/h) using 20° C fluids at 20° C ambient temperature, the H-250/D-50 system gave the highest temperatures throughout the range and showed effective warming from 1,300 ml/h on over the entire range tested (35° C at 17,000 ml/h) compared to the RSLB 30 H Gamida system (3,000–18,000 ml/h) (Fig. 2). This difference in performance was almost abolished with fluids at 6° C (Fig. 4). Similar efficacy could be reached by using prewarmed infusions that gave effective warming at 〉2,000 ml/h and reached 39° C at 13,000 ml/h. Prewarmed infusions could be used effectively down to 〉80 ml/h applying “active insulation” (Autotherm/Autoline) to the whole infusion system. The Hotline HL-90 (50–4,700 ml/h) appeared to be the most effective in-line warmer in the low (〈250 ml/h) and middle (250–2,500 ml/h) flow range, followed by the Astotherm IFT 260 (400–4,000 ml/h), but only if used with a length of 40 cm down-stream from the heat exchanger (Fig. 1). Increasing this distance to 145 cm markedly reduced its efficacy below the range of 2,000 ml/min (1,200–3,000 ml/h) (Fig. 5). The Bair Hugger 241 Prototype showed a narrow effective range (700–1,300 ml/h) that could be extended beyond 1,300 ml/h by the use of prewarmed infusions (Figs. 1 and 3). The performance for 6° C solutions and ambient temperatures of 25° C are given in Fig. 4 and Table 1. Conclusions. The importance of infusion warming increases with the amount of fluid given. In general, the infusion bag temperature only influenced the efficacy of in-line warmers within the high-flow range, challenging the performance of the heat exchanger. The length of uninsulated i.v. line downstream from the heat exchanger influenced the efficacy within the low- and middle-flow range, as did the room temperature. Prewarmed solutions can be infused very effectively within the high-flow range. This efficiency can be preserved down to the low-flow range by using “active insulation” of the infusion system. In-line warming is essential for emergency and rapid massive transfusions.