Legal and ethical implications of defining an optimum means of achieving unconsciousness in assisted dying.

A decision by a society to sanction assisted dying in any form should logically go hand-in-hand with defining the acceptable method(s). Assisted dying is legal in several countries and we have reviewed the methods commonly used, contrasting these with an analysis of capital punishment in the USA. We expected that, since a common humane aim is to achieve unconsciousness at the point of death, which then occurs rapidly without pain or distress, there might be a single technique being used. However, the considerable heterogeneity in methods suggests that an optimum method of achieving unconsciousness remains undefined. In voluntary assisted dying (in some US states and European countries), the common method to induce unconsciousness appears to be self-administered barbiturate ingestion, with death resulting slowly from asphyxia due to cardiorespiratory depression. Physician-administered injections (a combination of general anaesthetic and neuromuscular blockade) are an option in Dutch guidelines. Hypoxic methods involving helium rebreathing have also been reported. The method of capital punishment (USA) resembles the Dutch injection technique, but specific drugs, doses and monitoring employed vary. However, for all these forms of assisted dying, there appears to be a relatively high incidence of vomiting (up to 10%), prolongation of death (up to 7 days), and re-awakening from coma (up to 4%), constituting failure of unconsciousness. This raises a concern that some deaths may be inhumane, and we have used lessons from the most recent studies of accidental awareness during anaesthesia to describe an optimal means that could better achieve unconsciousness. We found that the very act of defining an 'optimum' itself has important implications for ethics and the law.

[Verification of the endotracheal tube placement]. / Uberprüfung der Tubuslage.

Verification of the correct position of the endotracheal tube is a daily routine task of every anaesthesiologist. Accidental intubation of the oesophagus is a very rare complication in absolute terms but still the most frequent preventable anaesthetic mishap with fatal outcome. Even the most experienced anaesthetist is not immune to this complication. Only vigilance on the part of the anaesthetist protects the patient. There is no absolutely reliable gold standard to diagnose the correct position of the tracheal tube. Visualization of the endotracheal tube between the vocal cords and a typical CO2 excretion waveform are two of the best practical signs. After every change of position of the patient, especially after flexion or extension of the head, the position of the tube must be checked again. The old aphorism is still valid: When in doubt, take it out.

[A method for the symmetrical pre-stretching of cuffs of plastic tubes (author's transl)[]. / Eine Methode zum symmetrischen Vordehnen des Cuffs von Plastiktuben

We describe a method to prestretch symmetrically cuffs of plastic endotracheal tubes. The tracheal wall pressure will be lower than the capillary pressure of the mucous membranes in tow third of the cases, if correctly prestrecthed cuffs are used. The importance of using truly high volume low pressure cuffs with a cuff diameter of a least 25 to 30 mm is stressed.

["Hepatitis" following halothane-anesthesia (author's transl)]. / "Hepatitis" nach halothananaesthesie.

"Hepatitis" following halothane-anesthesia is a rare complication, occurring once after about 2500 halothane-anaesthesias. The mortality is estimated to be 20-25%. The disease can be diagnosed by exclusion of other causes only. The differential diagnosis of postoperative jaundice is therefore briefly reviewed. Three hypotheses of possible pathogenic mechanisms are discussed, namely the theory of toxic products of the metabolism of halothane, the theory of delayed hypersensitivity to a metabolite and the theory of coincidence with preexisting unknown liver disease. None of these theories has been proved definitely. The use of halothane is contraindicated if a patient suffered from unexplained pyrexia and jaundice after a previous exposure to halothane. Gamma radiation decomposes halothane to hexachlorofluorobutene, a know hepatotoxin. The repeated use of halothane during irradiation therapy is therefore contraindicated. The risk of "hepatitis" after halothane anaesthesia increases if the patient is exposed to halothane twice within four weeks, especially if he is obese and older than 40 years. The risks and advantages of repeated halothane exposures have to be weighed against the risks of alternative techniques. The increased mortality after repeated anaesthesias within short periods of time, irrespective of the technique used, has to be considered.

[Anaesthesia in the extremely obese patient (author's transl)]. / Anaesthesie bei extremer Adipositas.

This paper reviews the literature on anaesthetic problems in extremely obese patients. The main concerns of the anaesthetist in these patients is pulmonary function, especially hypoxaemia. The pathogenesis of hypoxia is explained by an increased tendency to airway closure by the weight of fat, which compresses the thorax. The significance of the patient's position during and after operation is stressed. The Pickwick-Syndrome is extremely rare, even in large series of obese patients, but its diagnosis is important for therapeutic consequences. For anaesthesia in these patients neuroleptanaesthesia as well as classical inhalational procedures can be used.

[Subjective complaints of out-patients after halothane or enflurane anaesthesia (author's transl)]. / Subjektive Beschwerden nach Halothan- und nach Enfluraneanaesthesie bei ambulanten (Tagesklinik-) Patienten.

In a prospective and randomized study, day-patients receiving halothane or enflurane-anaesthesia (n = 42 resp. 59) were followed up by questionnaire to detect subjective complaints. There was no difference between the two anaesthetic agents. Despite the high incidence of complaints (88%), most of the patients would choose day-stay care (75%) and general anaesthesia (77%) again.

[The influence of the premedication on subjective postanaesthetic complaints in out-patients (author's transl)]. / Der Einfluss der Prämedikation auf die subjektiven post-anaesthetischen Beschwerden bei ambulanten (Tagesklinik-) Patienten.

Outpatients, premedicated with atropine i.v. (n=54) or the combination droperidol-fentanylatropine (n=123) complain significantly less frequently about nausea and/or vomiting than patients receiving pentazocine-atropine (n=64). Patients receiving the combination droperidol-fentanyl-atropine are significantly more sleepy and dysphoric in the post-anesthetic period. We do not recommend any premedication in outpatients with the possible exception of atropine.

[The influence of PaCO2 on oxygen consumption during extracorporeal circulation in hypothermia (author's transl)]. / Der Einfluss der arteriellen Kohlensäurespannung auf den Sauerstoffverbrauch während extrakorporellem Kreislauf in Hypothermie

Hypocapnia during extracorporeal circulation in hypothermia increases oxygen consumption. Po2 in mixed venous blood decreases. This probably reflects a decrease in tissue oxygen tension. Hyperventilation will therefore increase the risk of hypoxia in critically perfused tissues. Therefore we recommend to keep PaCO2 (T) constant at 40 mm Hg during hypothermia.

[Vocal dysfunction as a consequence of a paresis of the n. laryngeus cranialis after tracheal intubation (author's transl)]. / Stimmstörung infolge Lähmung des Nervus laryngeus cranialis nach Intubationsnarkose.

A case of a transient unilateral paresis of the N. laryngeus cranialis occuring after uneventful tracheal intubation and anaesthesia for laparoscopy is reported. The possible mechanisms of this paresis are discussed.

Blood gas analyses of hibernating hamsters and dormice.

Blood gases were measured in hibernating and hypothermic animals as a biological model of clinical hypothermia. Blood gas analyses from hamsters and dormice were carried out with the aid of permanent arterial catheters during normothermia and hibernation. In golden hamster pH increased from 7.30 to 7.46 during hibernation and PaCO2 decreased from 59.7 to 40.5 mm Hg. In dormice pH increased from 7.24 to 7.44 and PaCO2 decreases from 38.5 to 27.4 mm Hg. The actual bicarbonate concentration increased from 29 to 52 mMol in golden hamsters and from 16 to 34 mMol in dormice during hibernation. In experiments with induced hypothermia in golden hamsters under ketamine-anaesthesia there was no correlation between temperature and PaCO2. Despite the slight decrease in PaCO2 during hibernation we conclude that PaCO2 rather than total carbon dioxide content is held constant when temperature is changed. During clinical hypothermia it will probably be safe to keep PaCO2 constant.

[The prehospital phase of the acute myocardial infarct and its treatment in the mobile intensive care unit]. / Die Vorspitalphase des akuten Myokardinfarktes und ihre Beeinflussung durch mobile Intensivbehandlung

Mortality in the early phase of an acute myocardial infarction is high. Approximately two thirds of coronary deaths occur before the patients reach hospital, and if this mortality is to be reduced the prehospital phase must be shortened. For this purpose, mobile intensive care units are in use in many places with good results. The delay during the prehospital phase of acute myocardial infarction in Zurich has been analyzed prospectively (1) in a study performed in 1971/72 prior to the institution of the mobile intensive care unit ("Kardiomobil"), and (2) during the first year of Kardiomobil service. In 180 patients with acute myocardial infarction admitted to hospital by Kardiomobil the prehospital phase was considerably shorter (median delay 2 h 11 min) than in 216 with myocardial infarction in the same period not transported by Kardiomobil (7 hr 11 min) and in the 196 patients of the pre-Kardiomobil study (5 hr 55 min). Not only was the delay due to transport shorter in the Kardiomobil group but also the patient's and doctor's delays.

[Experiences with a mobile intensive care station (Kardiomobil) after 1 year's test operation in Zurich]. / Erfahrungen beim einjährigen Versuchsbetrieb mit einer mobilen Intensivbehandlungsstation (Kardiomobil) in Zürich

The Zurich mobile intensive care unit (Kardiomobil) admitted 502 patients in the first year of operation. 191 patients with confirmed acute myocardial infarction were seen. The Kardiomobil proved a success in shortening the total median delay between onset of symptoms and coronary care by 50%. Ten patients resuscitated outside the hospital were eventually discharged from hospital. 240 episodes of arrhythmia were observed in 182 of the 502 patients. 98 arrhythmias were successfully treated in this group, the best results being obtained in ventricular arrhythmias: 16 out of 26 patients with ventricular fibrillation were successfully defibrillated (61%), while 47 out of 53 episodes (89%) of frequent premature ventricular beats and all 9 episodes of ventricular tachycardia were corrected with lidocain and procainamid.

Validation of a simple algorithm for tracheal intubation: daily practice is the key to success in emergencies--an analysis of 13,248 intubations.

A fundamental skill of the anesthesiologist is airway management. We validated a simple endotracheal intubation algorithm with a large proportion of fiberoptic tracheal intubations used for years in daily practice. Over 2 yr, 13,248 intubations (>90% of all intubations, including obstetrics and ear, nose, and throat patients) in a heterogeneous patient population at our acute care hospital were evaluated prospectively. About 80 physician and nurse anesthetists were involved. Once the indication for intubation (oral or nasal) was established, the first step was to choose between the primary conventional technique (laryngoscope with Macintosh blades) and the primary fiberoptic technique. For the conventional technique, a well defined procedure had to be followed (maximum of two attempts at intubation; if unsuccessful, switch to secondary oral fiberoptic intubation). For the primary fiberoptic technique, the anesthesiologist had to decide between nasotracheal intubation in awake patients and oral intubation in anesthetized patients. Fiberoptics were used for 13.5% of the intubations. By following our algorithm, intubation failed in 6 out of 13,248 cases (0.045%; 95% confidence interval 0.02%-0.11%). We demonstrate that a simple algorithm for endotracheal intubation, basically limited to fiberoptics as the only aid, is successful in daily practice. Only methods that are practiced daily can be used successfully in emergencies.

[Intraoperative, direct and continuous measurement of stomach pH following pretreatment with ranitidine or sodium citrate]. / Die intraoperative, direkte und kontinuierliche pH-Messung im Magen nach Vorbehandlung mit Ranitidin oder Natriumcitrat.

We carried out continuous direct pH measurements of gastric fluid in 49 female patients pretreated with 300 mg ranitidine by mouth on the evening prior to surgery and 150 mg by mouth before the operation. A further 51 women were pretreated with 30 ml sodium citrate shortly before admission to the operating room. Twenty patients received 30 ml sodium citrate via a separate gastric tube after the first pH measurement; 22 were given no premedication. In 95% of cases, 30 ml sodium citrate was found to increase the pH to over 3.5 within 5 min; a failure rate of 5% can therefore be expected. This can be explained mainly by the failure of sodium citrate to mix thoroughly with the gastric fluid. Pretreatment with ranitidine increased the pH to over 4.0 in every case, and the pH on extubation was still over 4.0 even after delayed pH on extubation was still over 4.0 even after delayed or prolonged operations. We recommend that 30 ml sodium citrate be given shortly before the beginning of emergency obstetric operations. However, we prefer ranitidine for elective operations in patients at risk for aspiration because it increases of the gastric fluid pH to at least 4.0 in every case.

[The difficult intubation. The value of BURP and 3 predictive tests of difficult intubation]. / Die schwierige Intubation. Der Nutzen von BURP und die Aussagekraft von Prädiktoren.

UNLABELLED: The value of BURP (= backwards-upwards-rightwards-pressure of the larynx) was tested as a improvement of the visualisation of the larynx. Simultaneously we wanted to assess the value of different predictive tests of a difficult intubation, which are easy to perform as bedside tests. PATIENTS AND MATERIAL: 1993 patients of all different surgical clinics in a tertiary care hospital in Switzerland were tested, the complete anaesthesiological staff was involved. We registered the original Mallampati classes, the thyromental distances of Patil and Frerk and the difference of the jugulomental distances in maximally reclined and neutral head position according to Chow. Every anaesthetist also noted his personal, subjective opinion of a possible difficult intubation. Under optimal conditions for intubation we assessed the grade of laryngoscopy according to Wilson and applied BURP if the grade was 3 or higher. Both laryngoscopic grades and the difficulty of intubation were noted. RESULTS: In our study we found 12.5% awkward (Wilson G3-G5) and 4.7% difficult (Wilson G4-G5) laryngoscopies. These could be changed with BURP into 5.0% and 1.9% respectively. With BURP we found 1.8% of difficult intubations. During our study we did not find any patients, whom we could not intubate either with a mandrin inside the tube or with help of the fiberoptic. The relation between sensitivity and specificity was in all single predictors and in two combinations very low. Our personal subjective predictions proofed to be better, but the rate of false negatives was too high for clinical use. CONCLUSION: BURP is a valuable method for rendering the majority of difficult laryngoscopies into easy ones. It is very easy to learn and does not need any additional equipment. Three commonly used and recommended predictive tests of the difficult intubation proofed to be of little use in clinical practice.

[Perioperative myocardial infarction and cardiac complications after noncardiac surgery in patients with prior myocardial infarction. I. Clinical data and diagnosis, incidence]. / Perioperativer Myokardinfarkt und weitere kardiale Komplikationen nach nichtkardialen Wahloperationen bei Patienten nach Myokardinfarkt. I: Klinische Daten und Diagnostik, Inzidenz.

UNLABELLED: Patients with a prior myocardial infarction (MI) have a high risk of perioperative reinfarction compared with the normal population (5%-8% vs. 0.1%-0.7%) [10]. According to Rao [13], a reduction of this risk is possible when patients are monitored invasively and all haemodynamic parameters are kept within the physiological range. In most institutions it is not feasible to treat patients as Rao recommended: this would overstrain both hospital structure and financial resources. We studied the incidence of perioperative MI and other cardiac events in patients with prior MI. During the study period the anaesthesia and intensive care methods of our institution were neither changed nor influenced. In addition to this clinical evaluation, we performed perioperative Holter electrocardiographic monitoring and measured serum levels of the recently introduced marker troponin T (parts II and III). METHODS: Institutional informed consent was obtained. The study was planned prospectively. All patients with prior MI (156) and/or coronary artery bypass grafting (CABG) (4) who were scheduled for elective noncardiac surgery between April 1992 and March 1993 were included. The following information was acquired and tabulated: age, sex, body weight, preoperative risk factors, ASA classification, preoperative blood pressure, pulse rate, and ECG (interpreted by an independent cardiologist), serum electrolytes, haemoglobin, creatine kinase (CK), CKMB faction, creatinine. Preoperative regular medications, type of anaesthesia, type, site, and duration of surgery, and intraoperative haemodynamic changes were documented. The patients were divided into four groups depending on the time interval between MI and surgery (group I: 0-3 months, group II: 3-6 months, group III: > 6 months, group IV silent MI and prior CABG without infarction). We then studied the number of patients who developed a perioperative MI or died of cardiac causes within 7 postoperative days (n = 160). Because of early discharge of 21 patients, we could study the occurrence of cardiac events within 7 postoperative days in 139 patients only. Definitions of perioperative MI included [3]: changes of ST pattern (horizontal ST depression > 0.1 mV or elevation > 0.2 mV) during 30 s and longer; new T-negativation or Q-wave; pathological CKMB fraction (> or = 6% of total CK); and angina pectoris; two of these criteria were required to be positive (WHO). Definitions of cardiac events included: ischaemia: any reversible horizontal depression of the ST segment of more than 0.1 mV or any ST segment rise of more than 0.2 mV. Patients with bundle branch block (BBB) were excluded; angina pectoris: any chest pain that disappered after application of nitroglycerine; arrhythmia: any change from preoperative rhythm or appearence of ventricular premature beats; and left ventricular failure: clinical and radiological signs of ventricular failure. Statistical evaluation of the demographic data was performed by the Kruskall-Wallis test; categoric variables were examined using the chi 2 test and Fisher's exact test. P values of less than 0.05 were considered significant. RESULTS: Six of the 160 patients with prior MI developed a perioperative MI (3.8%); 2 of them (33%) died of cardiac causes (3rd and 6th postoperative day). All of these patients were in groups III or IV (interval > 6 months). Forty-two patients had one or more other cardiac events; arrhythmias (22) and ischaemia (14) were most common. Intraoperative hypotension was associated with postoperative MI (5 of 58 vs. 1 of 102). Preoperative congestive heart failure (4 of 18 vs. 3 of 121) and major surgery (7 of 68 vs. 0 of 71) led more often to postoperative left ventricular failure. Patients who received beta-blocking agents preoperatively had significantly fewer ischaemic cardiac events (0 of 28 vs. 14 of 90, 21 patients excluded with BBB) but differed in mean age (67 vs. 71 years). The use of beta-blocking agents was not associated with a reducti

Preoperative values of molecular coagulation markers identify patients at low risk for intraoperative haemostatic disorders and excessive blood loss.

Conventional laboratory investigations of haemostasis like prothrombin time and activated partial thromboplastin time are not useful in predicting and managing intra-operative bleeding complications. In order to establish a possible "perioperative reference range" for thrombin generation prothrombin fragment F1+2 (F1+2) and fibrin degradation (D-dimer) markers, we measured F1+2 and D-dimer concentrations before surgery (but after induction of anaesthesia), 30 minutes into surgery, 10 minutes after the event expected to induce the maximal activation of the haemostatic systems, 90 minutes after surgery and on postoperative days 1 and 2 in 226 consecutive patients. Samples were collected from arterial lines. Twenty patients developed a clinically defined, intraoperative disorder of haemostasis, 206 did not. Patients with an intraoperative disorder of haemostasis had significantly higher preoperative F1+2 and D-dimer concentrations. Preoperative values for F1+2 and D-dimer concentrations above the 75th percentile of patients without an intraoperative disorder of haemostasis indicated a 2.70 to 2.88 fold risk of developing an intraoperative disorder of haemostasis (odds ratios were 3.04, 3.12 and 3.29 for D-dimer, ELISA, F1+2, and D-dimer latex tests, respectively with 95% confidence intervals from 1.20 to 8.46) with negative predictive values of 94%, but positive predictive values of only 16% to 26%. These data suggest that preoperative determination of molecular markers might be helpful in identifying a group of patients at high risk for intraoperative disorder of haemostasis by exclusion of low risk patients. Validation of such an approach requires a prospective trial.