The laryngeal tube for difficult airway management: a prospective investigation in patients with pharyngeal and laryngeal tumours.

BACKGROUND AND OBJECTIVE: Since the introduction of the laryngeal mask into clinical practice, various additional supraglottic ventilatory devices have been developed. Although it has been demonstrated that the laryngeal tube is an effective airway device during positive pressure ventilation no clinical study has been performed thus far regarding its use in patients with predicted ventilation and intubation difficulties. METHODS: The aim of this study was to prospectively evaluate the use of the laryngeal tube for temporary oxygenation and ventilation in adult patients with supraglottic airway tumours scheduled to undergo a pharyngeal-laryngeal oesophagoscopy and bronchoscopy under general anaesthesia. In addition to our standard airway management with face mask ventilation and rigid bronchoscopy, all patients were temporarily ventilated with an laryngeal tube. Also, in patients requiring laryngeal biopsies, endotracheal intubation was performed with a 6.0 mm microlaryngeal tracheal tube. Minute ventilation volumes, tidal volumes, ventilation pressures, end-expiratory CO2 concentration, oxygen saturation and arterial blood gas samples were measured. RESULTS: From 54 enrolled patients only patients with relevant tumour masses were evaluated (n = 23). Mask ventilation was performed without difficulty in 15 of 23 patients. Mechanical ventilation with the laryngeal tube was possible in 22 of 23 patients with an audible leak present in three. Conventional endotracheal intubation was successfully performed in 19 of 23 patients. During face mask ventilation, minute volume, tidal volume, ventilation pressure, end-tidal CO2, oxygen saturation and arterial PO2 were significantly lower and PCO2 significantly higher (P < 0.05, paired t-test). No statistically significant differences were noted between the laryngeal tube and the microlaryngeal tracheal tube. CONCLUSIONS: The possibility of difficult ventilation and intubation must always be considered, in patients with supraglottic airway tumours. In these cases, the laryngeal tube can be considered for routine airway management and may be useful in the 'cannot-intubate' situation although difficulties should be anticipated in patients with previous irradiation, specifically of the throat area.

Influence of EEG monitoring on intraoperative stapedius reflex threshold values in cochlear implantation in children.

BACKGROUND: Cochlear implantation is a widely used means of treating deafness and severe hearing disorders. The surgical procedure includes inserting the cochlear implant electrode array into the cochlea and embedding the corresponding signal receiver in the mastoid bone behind the ear. Postoperative fitting of the externally worn speech processor is very important for successful use of the cochlear implant. For this purpose, electrically elicited stapedius reflex threshold values can be used. However, stapedius reflex threshold values measured intraoperatively are influenced by anaesthetics. The goal of this retrospective study was to find out whether electroencephalogram (EEG) control of anaesthesia produces more reliable reflex threshold values as a basis for the fitting of the speech processor. METHODS: Three groups of children, after surgery for cochlear implantation, were analysed with regard to the magnitude of intraoperative electrically elicited stapedius reflex threshold values and their deviations from postoperatively determined maximum comfortable levels (group 1: methohexital/remifentanil with EEG monitoring, n = 10; group 2: isoflurane/fentanyl with EEG monitoring, n = 9; group 3: isoflurane/fentanyl without EEG monitoring, n = 11). RESULTS: Children with EEG monitoring had significantly lower electrically elicited stapedius reflex threshold values and also significantly lower differences between intraoperative stapedius reflex threshold values and postoperatively determined maximum comfortable levels. CONCLUSIONS: Electroencephalogram monitoring in cochlear implantation is of considerable value in controlling anaesthesia and improving speech processor fitting based on more reliable intraoperative neurophysiological data.

No implicit memory for stories played during isoflurane/alfentanil/nitrous oxide anesthesia: a reading speed measurement.

UNLABELLED: Implicit memory of intraoperatively presented stories was recently detected by using the reading speed paradigm during propofol-alfentanil-nitrous oxide anesthesia. Our main goal was to evaluate the reading speed test procedure under another anesthetic regimen, i.e., isoflurane combined with nitrous oxide and alfentanil-infusion. In both experiments, patients were premedicated with oral midazolam. In a previous experiment, patients postoperatively read "old" stories that had been presented during anesthesia quicker compared with "new," unpresented stories. The same study design and test material as in the previous experiment were used. One of two audio tapes with two short stories was played randomly to patients during lumbar disk surgery and to awake controls. Approximately 7 h later, a structured interview and the reading speed test were used to determine whether the participants had any explicit or implicit memories of the presented stories. The results of 30 patients and 30 controls were calculated. Whereas the control participants showed an intact explicit and implicit memory of the previously presented material, no such effect was found in the anesthetized patients. The present experiment shows that changing the main anesthetic in otherwise equal study conditions, i. e., propofol to isoflurane (end-expiratory 0.7%), implicit memory is abolished in anesthetized patients. IMPLICATIONS: We showed that implicit memory during general anesthesia can be abolished by changing the hypnotic anesthetic. Increased postoperative reading speed for stories presented during propofol-alfentanil-nitrous oxide anesthesia was shown in a previous experiment, but not in our study using isoflurane for balanced anesthesia.

Increased reading speed for stories presented during general anesthesia.

BACKGROUND: In the absence of explicit memories such as the recall and recognition of intraoperative events, memory of auditory information played during general anesthesia has been demonstrated with several tests of implicit memory. In contrast to explicit memory, which requires conscious recollection, implicit memory does not require recollection of previous experiences and is evidenced by a priming effect on task performance. The authors evaluated the effect of a standardized anesthetic technique on implicit memory, first using a word stem completion task, and then a reading speed task in a subsequent study. METHODS: While undergoing lumbar disc surgery, 60 patients were exposed to auditory materials via headphones in two successive experiments. A balanced intravenous technique with propofol and alfentanil infusions and a nitrous oxide-oxygen mixture was used to maintain adequate anesthesia. In the first experiment, 30 patients were exposed randomly to one of the two lists of 34 repeated German nouns; in the second experiment, 30 patients were exposed to one of two tapes containing two short stories. Thirty control patients for each experiment heard the tapes without receiving anesthesia. All patients were tested for implicit memory 6-8 h later: A word stem completion task for the words and a reading speed task for the stories were used as measures of implicit memory. RESULTS: The control group completed the word stems significantly more often with the words that they had heard previously, but no such effect was found in the anesthetized group. However, both the control and patient groups showed a decreased reading time of about 40 ms per word for the previously presented stories compared with the new stories. The patients had no explicit memory of intraoperative events. CONCLUSIONS: Implicit memory was demonstrated after anesthesia by the reading speed task but not by the word stem completion task. Some methodologic aspects, such as using low frequency words or varying study and test modalities, may account for the negative results of the word stem completion task. Another explanation is that anesthesia with propofol, alfentanil, and nitrous oxide suppressed the word priming but not the reading speed measure of implicit memory. The reading speed paradigm seems to provide a stable and reliable measurement of implicit memory.

[Intubation conditions and the development of neuromuscular blockade with rocuronium in endoscopic ORL surgery]. / Intubationsbedingungen und Verlauf der neuromuskulären Blockade nach Rocuronium bei endoskopischen Operationen in der HNO-Heilkunde.

UNLABELLED: Rocuronium is a new nondepolarizing muscle relaxant for which a fast onset has been described. The goal of this study was to examine whether the characteristics of rocuronium could make it an appropriate relaxant for the anaesthetic management of operations of intermediate duration such as endoscopic upper airway surgery. These operations, which require the anaesthesiologist and surgeon to "share" the patient's airway, require good muscle relaxation for endotracheal intubation and placement of endoscopic instruments. In addition, the time course of neuromuscular blockade and its relation to the quality of intubating conditions were analysed. METHODS: The study was approved by the local ethics committee; 30 patients (ASA status 1-3) scheduled for elective endoscopic upper airway surgery were included after written informed consent. Exclusion criteria were suspected difficult intubating conditions, neuromuscular disease, or antibiotic therapy with aminoglycosides during the last 24 h. Anaesthesia was induced by propofol 2 mg/kg and alfentanil 1 mg after volume loading with 500 ml Ringer's lactate and preoxygenation, and was maintained by propofol infusion 5-8 mg/kg/h and repetitive alfentanil injections according to clinical needs. Endotracheal intubation was performed by a senior anaesthesiologist 90 s after injection of rocuronium 0.6 mg/kg (2 x ED95). Intubating conditions were graded 1 to 4 (1 = excellent, 2 = good, 3 = sufficient, 4 = inadequate). Acceleromyography was used for neuromuscular monitoring by means of the TOF-guard (organon Teknika/Biometer). The adduction movement of the thumb was measured by an acceleration transducer while stimulating the ulnar nerve at the wrist via surface electrodes in a supramaximal train-of-four (TOF) mode (2 Hz every 15 s). Twitch height and TOF ratio were documented during the course of neuromuscular blockade. Data are presented as mean +/- standard deviation. RESULTS: Patients were aged 37 to 64 years (mean 54 +/- 7). Intubating conditions were excellent in 17 cases and good in 7. In 2 cases intubating conditions were graded sufficient, as patients could be easily intubated but showed clear diaphragmatic movements at intubation. In 4 patients intubating conditions could not be judged, as a laryngoscopic view of the glottic structures was impossible for anatomic reasons. Neuromuscular block at intubation was 78 +/- 22%, onset time 152 +/- 62 s, clinical duration 30 +/- 8 min, and recovery index 11 +/- 4 min. The TOF ratio required 51 +/- 14 min to return to 0.7. CONCLUSIONS: Good to excellent intubating conditions can be expected 90 s after injection of rocuronium 0.6 mg/kg. Diaphragmatic reactions cannot be excluded. Complete relaxation of the adductor pollicis muscle is not necessary for endotracheal intubation. Intubation at a certain time interval, for example, 90 s after injection of rocuronium 0.6 mg/kg, can be recommended. Onset and recovery characteristics of rocuronium make it an appropriate relaxant for the anaesthetic management of operations of intermediate duration such as endoscopic upper airway surgery. Care should be given, however, to detect inadequate recovery of neuromuscular transmission, as there are considerable interindividual differences in recovery.

[Effect of anesthesia on the intraoperative elicited stapedius reflex]. / Der Einfluss der Narkose auf den intraoperativ elektrisch ausgelösten Stapediusreflex.

Evaluation of the intraoperative electrically evoked stapedius reflexes during cochlear implant surgery has two purposes: (1) The functioning of the device and the peripheral auditory pathways can be proven immediately and (2) The data of reflex threshold can be used for the prediction of later threshold (T)- and maximum comfortable (C) levels. This is especially useful for the later fitting of the speech processor in very young children. When trying to use the stapedius reflex data for the prediction of T- and C-levels it must be considered that during surgery the drugs used for general anaesthesia influence the values of the stapedius reflex. Depending on the drug, the stapedius reflex threshold can be increased or the reflex can even be totally blocked. This is not only due to relaxants but also to anaesthetics. To investigate this influence we first determined the acoustically evoked stapedius reflex threshold in normal hearing adults under general anaesthesia with 7 different anaesthetics without additional relaxation. It was found that especially with Dormicum and Brevimytal the stapedius threshold increased only very lightly or did not change at all. In a second investigation the electrically evoked stapedius reflex thresholds were obtained in adults who underwent a cochlear implant surgery using the same anaesthetics for anaesthesia. The intraoperatively evaluated reflex data were compared with postoperatively obtained data. It was found that both reflex thresholds were similar if evaluated in Dormicum or Brevimytal anaesthesia. This suggests that only with the use of the right anaesthetics the data of the electrically evoked stapedius reflex obtained intraoperatively can be used for predicting T- and C-levels.

[Percutaneous transtracheal ventilation using Nu-Trake cricothyreotomy instruments and tracheoscopic follow-up examination]. / Perkutane transtracheale Ventilation (PTV) mit dem Krikothyreotomiebesteck Nu-Trake und tracheoskopische Kontrolluntersuchungen.

Practicability and efficiency of the cricothyreotomy set Nu-Trake was investigated in corpses (n = 10) in the institute of Pathology and clinically in laryngectomy patients (n = 5) including endoscopical controls. The practicability proved to be good, the time needed to perform the coniotomy did not last longer than 2 minutes. But complications in the investigation on the corpses could not be avoided. These were missing the lumen of the trachea, perforation of the pars membranacea tracheae and fracture of the cricoid. The clinical investigation demonstrated a sufficient oxygenation and ventilation in all patients during the whole investigation period (30 min). This can be explained by the diameter of 7.2 mm of the used tube. Endoscopic controls showed a sufficient distance of the tip of the tubes from the pars membranacea tracheae and almost no bleeding within the trachea. Similar as with other coniotomy-technics the cricothyreotomy with the Nu-Trake set bears the risk of typical complications which have to be overcome by training of this important measure of emergency.

[Failed intubation with case reports]. / Misslungene Intubation mit Kasuistiken.

Failed intubation in three patients is reported. All three patients suffered sudden, extreme impaired of mask-ventilation. Twice a coniotomy with subsequent tracheostomy proved to be life saving and without permanent injury. In the other patient tracheostomy had been attempted without success, and subsequent, successful, coniotomy could not prevent cerebral ischemia. Coniotomy is the only correct emergency operation for failed intubation with impaired mask ventilation. It must be followed by a standard tracheostomy with closure of the coniotomy wound to prevent permanent laryngeal damage.

[Effect of the neuroleptic fluphenazine dihydrochloride on the cardiovascular system of polytraumatized patients with an alcoholic anamnesis]. / Die Wirkung des Neuroleptikums Fluphenazin-dihydrochlorid auf das Herz-Kreislaufsystem Polytraumatisierter mit Alkoholanamnese.

Haemodynamic effects in 10 multi-injured patients were registered after a bolus injection of 20 mg fluphenazin-dihydrochloride (Dapotum acutum; Fa. Heyden). Favourable results were seen in pre- and afterload. Parameters such as TTI, TTIB, CE and TI, characterising myocardial oxygen consumption, were also influenced positively. A reduction of mean arterial pressure can be avoided by administering slowly increasing volume and, occasionally, catecholamines. By use of modern monitoring in ICV, thus drug seems to be free from risk.

[Hemodynamic effects of mexiletine and lidocaine in coronary surgery patients]. / Hämodynamische Effekte von Mexiletine und Lidocain bei koronarchirurgischen Patienten.

In two groups of 10 coronary bypass patients during the postoperative phase a comparison was carried out of the haemodynamic effects of mexiletine and lidocaine in order to evaluate mexiletine's applicability as an antiarrhythmic in intensive care patients. With mexiletine cardiac effort (CE) fell by 6%, total peripheral resistance (TPR) fell by 11%, while CO increased by 8%. With lidocaine CE and TPR remained unchanged, CO dropped by 4%. Mexiletine seems to be applicable in intensive care without hazards to circulation.

[Cardiac arrest caused by air embolism in the course of a partial liver resection--a rare anaesthesiological complication (author's transl)]. / Herzstillstand durch Luftembolie bei Leberteilresektion--eine ungewöhnliche anaesthesiologische Komplikation!

Cardiac arrest occurred during resection of a metastasis of the liver. In spite of having a PEEP of 5 cm H2O during IPPV this could not be avoided. Beginning immediately with reanimation a "Restitutio ad integrum" was seen as demonstrated by EEG and ECG.