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Description / Table of Contents: Abstract. After laparoscopic cholecystectomy, carbon dioxide (CO2) must be exhaled after resorption from the abdominal cavity. There is controversy about the amount and relevance of postoperative CO2 resorption. Without continuous postoperative monitoring, after laparoscopic cholecystectomy a certain risk may consist in unnoticed hypercapnia due to CO2 resorption. Studies exist on the course of end-expiratory CO2 (PeCO2) alone over a longer postoperative period of time in extubated patients during spontaneous breathing. The goal of this prospective study was to investigate the amount of CO2 resorbed from the abdominal cavity in the postoperative period by means of CO2 metabolism. Methods. After giving informed consent to the study, which was approved by the local ethics committee, 20 patients underwent laparoscopic cholecystectomy. All patients received general endotracheal anaesthesia. After induction, total IV anaesthesia was maintained using fentanyl, propofol, and atracurium. Patients were ventilated with oxygen in air (FiO2 0.4). The intraabdominal pressure during the surgical procedure ranged from 12 to 14 mm Hg. Thirty minutes after releasing the capnoperitoneum (KP), CO2 elimination (V˙CO2), oxygen uptake (V˙O2), and respiratory quotient (RQ) were measured every minute for 1 h by indirect calorimetry using the metabolic monitor Deltatrac according to the principle of Canopy. Assuming an unchanged metabolism, the CO2 resorption (ΔV˙CO2) at any given time (t) can be calculated from ΔV˙CO2 (t)=V˙CO2 (t)−RQ (preop) V˙O2 (t). It was thus necessary to define the patient's metabolism on the day of operation. The first data were collected before surgery and after introduction of the arterial and venous cannulae for a 15-min period. Measuring point 0 was determined after exsufflation of the KP and emptying of the remaining CO2 via manual compression by the surgeon at the end of surgery. Patient's tracheas were extubated and metabolic monitoring started 30 min after release of the KP for 60 min. Simultaneously, a nasal side-stream capnometry probe was placed and the PeCO2 and respiratory frequency (RF) were obtained by the Capnomac Ultima (Datex) and registered every minute as well. Values were averaged over four periods of 15 min each. An arterial blood gas sample was drawn at the end of every 15-min period. Postoperative pain was scored by a visual analog scale and completed by a subjective index questionnaire on general well-being. All data were analysed by the Friedman or Wilcoxon test;P〈0.05 was considered significant. Results. The findings do not indicate CO2 resorption in the postoperative period after laparoscopic cholecystectomy (Tables 2 and 3, Fig. 1). Arterial CO2 as well as PeCO2 were elevated postoperatively (45 mm Hg vs. 36 mm Hg intraoperatively), while V˙CO2 and V˙O2 were unchanged when compared to the preoperative measuring period. The postoperative RF was comparable to preoperative values. Calculated ΔCO2 was lower than 10 ml/min and within accuracy of measurements. The postoperative pain index ranged between 3 and 4, and 3.75 – 15 mg piritramid was administered. All patients feld tired immediately after the operation, but scores improved slightly at the end of the 60-min period of metabolic monitoring. Conclusions. There is no significant resorption of CO2 from the abdominal cavity later than 30 min after releasing the KP. Up to this time, any CO2 remaining in the abdominal cavity after careful emptying by the surgeon has been resorbed and exhaled. An increased PeCO2 as late as 30 to 90 min postoperatively should rather be considered a consequence of residual anaesthetics and narcotics than of CO2 resorption.

Description / Table of Contents: Abstract. Introduction. For many years, the main goal of premedication was prevention of the dangerous side effects sometimes encountered in anesthetics with anticholinergics, antiemetic antihistaminics, and opioids. Because the rules were always preoperative fasting, premedication was administered i.m. Thus, the onset of action was within 15 – 30 min from administration. In recent years, with the introduction of newer anesthetics with fewer side effects, anxiolysis became the main aim in premedication. Moreover, the oral route became popular since it obviously did not increase the acidity or volume of the gastric content. However, the uptake and thus onset of action of orally administered drugs may take longer and can differ considerably between individual patients. Therefore, the optimum interval between administration and induction of anesthesia remains controversial. The present study was carried out to examine the time course of drug action and the effects of different premedication regimens on the electroencephalogram (EEG). Patients and methods. After obtaining informed consent, in 38 unselected adult patients (ASA I and II, 〈65 years) scheduled for elective surgery, the EEG was recorded continuously before and after premedication. The patients were randomly assigned to four groups: M: midazolam, 0.2 mg/kg BW orally; N: nordazepam, 0.2 mg/kg BW orally; AP: atropine, 0.5 mg, plus promethazine, 50 mg i.m.; APP: atropine, 0.5 mg, plus promethazine, 50 mg, plus pethidine, 0.7 mg/kg BW i.m. The EEG was recorded for a reference period of 10 min before and a study period of 30 min after premedication. Automated EEG processing was performed with CATEEM® (computer-aided topographical electroencephalometry). Surface electrodes were placed according to the 10 – 20 system. Date were collected via an amplifier (resistance 10 MΩ) and a digitalization unit (filter 0.2 – 35 Hz, sampling rate 512 Hz, 12 bit A/D convertor). The original EEG signals were used in an interpolation algorythm to produce an additional 82 virtual recording points, allowing for high topographical resolution. After spectral analysis (fast Fourier transformation), the different frequency ranges of the EEG power spectrum are displayed in different colors. The screen displays the on-line map with color-based topographical power distribution. In order to achieve a pharmacodynamic time profile, the study period was subdivided into three periods of 10 min each. For clinical evaluation of vigilance, a 6-grade scoring system was used (1=awake, 6=not arousable). Results. All data are presented with respect to reference period. The power density of each frequency range for each electrode is integrated over the selected period and mean values are shown. Changes in power density with time are expressed as percentage change from reference period. Biometrical data showed no significant differences between groups. The median vigilance score 30 min after premedication (end of study period) was 4 in groups M, AP, and APP, and 3 in group N. In both benzodiazepine groups, a distinct increase in power density was found in the β-bands, while in groups AP and APP the increase was most pronounced in the δ and θ bands. In group M, there was a linear increase in β 1 power up to 310%, while in the β 2 range there was a 170% maximum within the second period of 10 min. In group N, there was a similar course with a lower increase in β 1 (220%) and β 2 (130%). Increases in both β-bands were most pronounced with frontal electrodes. While group M showed an increase in δ power (150%), together with moderate suppression in α (α 1 50%, α 2 40%), nordazepam caused only a slight increase in δ (124%) and a distinct increase in α 2 to 150%, predominantly in the frontal areas. Group APP showed a linear increase in both δ up to 210% and θ power to 190%. Maximum increases in δ (170%) and θ (140%) in group AP, however, were less pronounced and occurred in the second period. In both groups there was suppression in α 1 (AP: 20 – 40%, APP: 40 – 60%) and α 2 (AP: 30 – 60%, APP: 40 – 60%). Conclusion. Our results indicate that premedication with oral benzodiazepines results in β-activation, corresponding to the anxiolytic effect, while the degree of sedation as expressed by δ and θ bands may depend on the specific drug and dosage. The lower vigilance scores in group N may suggest a lower degree of sedative effect or too low a dosage. When benzodiazepines with fast uptake kinetics are administered orally, pharmacodynamic EEG effects may occur as soon as 30 min or less after premedication.

Description / Table of Contents: Abstract Objectiles: Clinicians use patients’ recall of pain as an important source of evidence both in diagnosis and in assessing improvements following treatment. Yet very little is known about the accuracy of these retrospective accounts up to now. Methods: We examined patients’ retrospective evaluations of the pain they experienced at the first postoperative day and related these evaluations to the pain intensity which was recorded in the PCA-report. Results: We found that recall was moderately accurate. Patients mostly overestimated their pain intensity. We could demonstrate that patients who overestimated their pain differed significantly from those who did not. The patients who overestimated showed no significant pain relief over the first three postoperative days. Other influences were the pain intensity of the third day and patients’ expectations of the postoperative pain intensity. Our results could be embedded within the theoretical framework of general memory research. Conclusions: We conclude that real-time evaluations of pain intensity should be recorded additionally to retrospective accounts. Retrospective ratings are important too, because we suggest that the memory of pain more than the experience of pain itself form the basis of patients’ future decisions about treatment including their compliance and their satisfaction with pain management.

Description / Table of Contents: Abstract. Total intravenous anaesthesia (TIVA) is increasingly used in short-stay surgery such as laparoscopic cholecystectomy. TIVA may provide fast recovery of psychomotor function, thus being of benefit to both the patient's behaviour and postoperative management. The purpose of this prospective study was to compare postoperative recovery from TIVA using propofol or methohexitone as the hypnotic component and balanced anaesthesia with isoflurane. Patients and methods. After giving informed consent and approval by the ethical committee of our hospital, 51 patients (ASA I, II) were investigated in a prospective study. Patients were randomised to receive either isoflurane, methohexitone, or propofol. Perioperative management with regard to premedication, intraoperative analgesia, relaxation, ventilation, and postoperative analgesia was carried out identically for all groups. Postoperative vigilance, pain, and nausea scores were assessed 15, 30, 60, 120, and 360 min after extubation with a visual analogue scale (VAS). At the same points, psychomotor recovery was investigated with the following assays: sedation as shown in Table 1; orientation with ten questions as to person, time, and location; memory as expressed by the patient's ability to repeat five words; a calculation test with five subtractions of the number 7 beginning from 100; and word generation by the number of words with an initial "m" given within 1 min and with animal names. Data were analysed with Kruskal Wallis' test for multiple comparisons between the groups and with Friedman's test for repeated measurements. All values are given as medians (interquartile range) or ranges. Results. There was no difference between the groups' physical condition (Table 2). All intraoperative parameters compared well between groups; the management of anaesthesia was smoother with isoflurane than with the other anaesthetics. Psychomotor recovery was somewhat faster in the propofol group than the methohexitone group, as indicated by sedation score, orientation, memory and calculation tests (Table 4), word generation tests (Fig. 4), and subjective vigilance score (Fig. 3). The difference in recovery time between the propofol and isoflurane groups was minimal and without any significance or relevance. The incidence of postoperative nausea was significantly lower after balanced anaesthesia with isoflurane (24%, P〈0.05) as compared to TIVA with either propofol (53%) or methohexitone (41%). However, there were only minor differences between the groups; the ability to cooperate and be mobilised was not limited. Discussion. Each of the three techniques used in this study is suitable for anaesthesia in patients undergoing laparoscopic cholecystectomy. Since fast recovery of vigilance and psychomotor function is very important in outpatient surgery, opioid-supplemented propofol anaesthesia is well established. Inhalation anaesthesia with isoflurane in air/oxygen without adding nitrous oxide compares well to propofol TIVA for laparoscopic surgery.

Description / Table of Contents: Abstract Objectives: Continuous epidural analgesia (EA) and patient-controlled intravenous analgesia (PCA) are widely used for postoperative pain control. Studies indicate that both analgesic regimens provide good analgesia after major surgery. However, because of the following reasons it is still unclear whether one of the two modes of application is superior. First, there are conflicting data regarding the differences in pain relief and drug use between epidural and intravenous administration of opioids. Second, in many studies epidural analgesia is performed by a combination of local anaesthetics and opioids. Third, reduced morbidity was observed only in some of the studies, in which epidural analgesia provided better pain relief than systemic opioid supply. Despite these conflicting results, EA with local anaesthetics and fentanyl as well as PCA with piritramid, a highly potent μ-agonist, are routinely used in Germany. The purpose of this study was to compare these two treatments for analgesic efficacy, pulmonary function, incidence of side effects and complications in patients undergoing thoracotomy. Methods: In this prospective randomized trial 50 patients were included. For postoperative pain control 25 patients (EA group) received thoracic epidural infusion of local anaesthetics (bupivacaine 0.125% or ropivacaine 0,2%) and fentanyl 4,5µg/ml with a flow rate of 4-10 ml/h. 25 patients received intravenous PCA with piritramid (bolus 2,5 mg, lock out 15 minutes, maximum of 25 mg/4 h, no background infusion). Results: Analgesia at rest and while coughing, as evaluated by visual analogue scale, was significantly better in the EA group. EA also resulted in superior values of pulmonary function tests, general condition and a lower incidence of sedation and nausea. In contrast, patients with EA reported distinctly more pruritus than patients with PCA. Duration of hospital stay was shorter in the EA group, but this difference did not reach statistical significance. There was one atelectasis in the EA group. No major complications related to EA or PCA were observed. Conclusion: In this study EA with local anaesthetics and fentanyl provided superior postoperative pain control and a lower incidence of sedation and nausea compared to intravenous PCA with piritramid, but there was no superiority as to pulmonary complications and duration of hospital stay.

Description / Table of Contents: Abstract Gamma-hydroxybutyric acid (GHB) is a naturally occurring transmitter in the mammalian brain, related to sleep regulation and possibly to energy balance in diving or hibernating animals. It has been used for almost 35 years as an intravenous agent for induction of anaesthesia and for long-term sedation. Its convincing pharmacological properties, without serious adresse effects on circulation or respiration, are compromised by its unpredictable duration of action. This is not a major problem with long-term sedation during ICU treatment. GHB has been used with good results for sedation of patients with severe brain injury, where it compares favourably with barbiturates. In animal studies, it seems to possess a protective action against hypoxia on a cellular and whole organ level. However, in some experimental animals GHB has been shown to produce seizure-like activities, and the compound is being used to produce absence-like seizures. GHB has been used in our ICU for years to provide adequate sedation for patients under controlled ventilation or for patients figthing the respirator during spontaneous respiration. No serious side effects were observed in these patients, while in some patients under haemodialysis hypernatraemia and metabolic alkalosis developed; both were reversible after discontinuation of GHB and restriction of additional sodium input (Somsanit, the commercially available GHB preparation in Germany, contains 9.2 mmol sodium/g; the daily dose averages 20–40 g GHB, i.e. 180–370 mmol sodium). Patients and methods. In 31 patients after major abdominal surgery, sedation was established with GHB 50 mg/kg BW injected via perfusion pump over a 20-min period. No centrally acting medication had been given for at least 2 h. A computer-based multichannel EEG system (CATEEM, MediSyst, Linden) was used, allowing for fast Fourier transformation, spectral analysis and topographical brain mapping. EEG during induction of sedation was followed after a baseline EEG (10 min) had been recorded. Patients receiving long-term sedation were studied daily for an additional 15-min period. Corresponding well to the clinical findings, EEG pattern changed to a slow delta-theta or delta-only rhythm within 10 min of the start of injection. Alpha and beta power decreased, while delta activity exhibited an increase. All changes were most obvious in frontal and central areas of the brain. In about one out of three patients, a burst – suppression pattern developed. Since automatic processing of EEG may fail to detect special patterns like the looked-for 3/s spikes and waves, the raw EEG was analysed visually by an expert neurologist. Both processed and conventionally analysed EEG were free of any seizure-like electrical activity. Conclusion. We conclude that animal data may not apply to the use of GHB in humans, provided the dose is limited to the clinical needs. GHB is used in clinical practice in doses twice as high, or even higher, than the one we use for induction, without obvious side effects. However, the suppression of theta rhythm we observed in about half of the patients studied may indicate that even less than 50 mg/kg BW might be sufficient for adequate sedation.

Description / Table of Contents: Zusammenfassung Bericht über die Ergebnisse einer vorläufigen Untersuchung an Gehirnen von Säuglingen mit hyalinen Membranen der Lungen (“Respiratory Distress Syndrome”). 21 Fälle dieser Erkrankung wurden untersucht, außerdem 4 Fälle mit anderen Erkrankungen und 2 Totgeborene. Der Hauptbefund, besonders bei Säuglingen mit einer Schwangerschaftsdauer von mehr als 30 Wochen, war zahlenmäßige Verminderung oder völliger Ausfall der Purkinje-Zellen. Man hatte nicht den Eindruck, daß dieser Befund etwas “Normales” beim Neugeborenen darstellt, oder daß er bei Tod nach anderen Erkrankungen häufig vorkommt. Ein Zusammenhang mit Geburtstrauma oder postnatalen chemischen Störungen wurde nicht festgestellt. Es wird vermutet, daß die Purkinje-Zellen bei Säuglingen mit hyalinen Membranen sich entweder überhaupt nicht normal entwickelt haben, oder daß sie im Uterus rasch zerstört wurden, und zwar im Zusammenhang mit einer noch nicht völlig geklärten Stoffwechselstörung. Schichtförmige Erbleichungen der Großhirnrinde durch Anoxaemie wurden häufig beobachtet, sie waren aber weniger charakteristisch als die Kleinhirnveränderungen.