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Background: Unrecognized esophageal intubation remains a significant cause of anesthetic morbidity. Extensive data showed that clinical signs and methods for confirming proper tracheal tube placement were not always reliable. Advancing tracheal tube into the trachea can be detected by palpating the cricoid cartilage. We evaluated the reliability of detecting tracheal intubation by cricoid palpation methods (CPM) in this study., Methods: Three hundred and twelve patients were enrolled. After induction of general anesthesia, patients' tracheae were intubated using rigid laryngoscope. Before tracheal intubation, an assistant applied gentle pressure over the cricoid cartilage to detect tracheal or esophageal intubation. Immediately after intubation, the assistant was asked to state whether the tracheal tube was in the trachea or in the esophagus on the basis of what had been felt as the tube passed. Tracheal intubation was confirmed by capnometer and auscultation., Results: In 304 tracheal intubations, the CPM correctly detected 268 cases, giving sensitivity of 88%. In 26 esophageal intubation, the CPM correctly detected 11 esophageal cases, giving specificity of 42%. Positive predictive value and negative predictive values were 95% and 23%, respectively. Increasing body mass index decreased the sensitivity for detecting tracheal intubation by the CPM., Conclusions: The CPM alone is imperfect for tracheal tube placement confirmation. Multiple methods for detecting correct tube placement should be used, since no single method has perfect reliability.

Background: Applying cricoid pressure is a simple and effective means of preventing aspiration of gastric juice and content. This procedure prevents a possible reflux by compressing the esophagus between the cricoid cartilage and the cervical vertebral bodies. Recent studies recommend a pressure of 30-40 N. The present study was undertaken to determine whether with education and practice, anesthesia assisitants could be taught a recommended cricoid pressure and retain this skill., Methods: Thirty-four participants (seventeen doctors, seventeen nurses) were asked to apply pressure to the blinded model to simulate application of maneuver on three occations: before instruction, after practice and 1 month after the practice. Cricoid force was measured using a life-size model on a calibrated scale., Results: Only four doctors and five nurses actually applied cricoid pressure effectively. After training, 13 doctors and 12 nurses applied cricoid pressure correctly. But they could not retain skill for 1 month., Conclusions: This model represents an easy and practical means of training the application of the optimal level cricoid pressure but the training should be continued.

We had 31 patients (8 males and 23 females) with postcricoid carcinoma in the period from 1978 to 1988. This number of patients correspond to about 15.3% of patient with hypopharyngeal carcinoma we encountered in this period. There were 4 patients in the condition Stage I, 8 in Stage II, 7 in Stage III and 12 in Stage IV. Most of these patients underwent radical surgery, 5-year cumulative survival rate was 46.8% (Kaplan-Meier). The cause of death was neck metastasis in 75% of patients who died of postcricoid carcinoma. There was a significant difference in survival curve between patients with neck metastasis and patients free from it (5-year cumulative survival rate was 68.0% and 16.7%, respectively; p less than 0.01). Neck metastasis was noted in the paratracheal region in 29.0% of patients. In patients with primary tumor of not larger 2.5cm (n = 7), no metastasis was noted, nor recurrence in this series of patients.

Acetylcholine receptors (AchRs) at the neuromuscular junctions of the cat posterior cricoarytenoid muscle (PCA muscle) were demonstrated by using erabutoxin b (Eb) which has a curare-like action. Eb is one of the short-chain neurotoxins which is obtained from Laticauda-semifasciata. At the light microscopic level, the localization of the neuromuscular junctions was detected on the muscle fiber by rhodamine-labeled Eb (TMR-Eb) under a fluorescein microscopy. For the electron microscopy horseradish peroxidase-labeled Eb (HRP-Eb) was used. After incubation with HRP-Eb conjugate the tissue was fixed in a mixture of paraformaldehyde and glutaraldehyde, then embedded in Epon. The reaction products were largely restricted to the postsynaptic membrane at the neuromuscular junction. Acetylcholinesterase (AchE) activity was also demonstrated electron microscopically by Karnovsky's and Lewis' methods respectively. The reaction products were localized at the subneural apparatus of the neuromuscular junction. Both these results were compared.