Composition of the extracellular matrix in human cricoarytenoid joint articular cartilage.
The extracellular matrix of the human cricoarytenoid joint articular cartilage is involved in different pathological changes. Interestingly, in contrast to the limb joints, the extracellular matrix composition of the healthy cricoarytenoid joint articular cartilage has not yet been elucidated except by some light microscopical investigations. The present study investigates the extracellular matrix components of the cricoarytenoid joint articular cartilage by means of light microscopy, immunohistochemistry, transmission electron microscopy and scanning electron microscopy and compares them with the limb joints for a better understanding of their involvement in joint disease. Chondrocytes near the joint surface of the cricoid and arytenoid cartilage differ from chondrocytes of deeper cartilage layers. The extracellular matrix of the articular cartilage contains chondroitin-4-sulfate, chondroitin-6-sulfate and keratansulfate as well as collagen types II, III, VI, IX and XI. Type-III-collagen shows a special distribution throughout the joint cartilage. In deeper cartilage layers, type-III-collagen occurs only pericellularly; in higher cartilage layers type-III-collagen is also located territorially and interterritorialy in small amounts. Scanning and transmission electron microscopy have revealed the articular surface of the cricoid and arytenoid cartilage to consist of a network of irregularly organized collagen fibrils, which are lined by a layer of electron dense material. The network coats subjacent collagen bundles which descend obliquely downward and intermingle at right angles in the middle part of the articular cartilage with collagen bundles of the deeper cartilage zones. The articular cartilage surface shows structural characteristics which differ from the underlying cartilage. The superficial electron dense layer possibly plays a role in the lubrication of the articular cartilage surface. The alignment of the fibrillar structures in the articular cartilage of the cricoarytenoid joint varies from those of the limb joints based on the different strain occurring during arytenoid movement. Nevertheless, the human cricoarytenoid joint articular cartilage can be compared with the joints of the limbs despite its extracellular matrix composition and its involvement in joint pathology. Evidence of type III collagen in the outermost layer of the articular cartilage of the cricoarytenoid joint presents a peculiarity, which has yet not be demonstrated in the articular cartilage of limb joints. (+info)
New insights into the pathomechanism of postintubation arytenoid subluxation.
BACKGROUND: Impaired movement of the cricoarytenoid joint with hoarseness and immobility of the vocal ligament can occur as a consequence of endotracheal intubation. The biomechanics and pathomechanism of cricoarytenoid subluxation have not been demonstrated to date. METHODS: The present study attempts to simulate the trauma that has been associated with arytenoid cartilage subluxation in intubation trials on 37 unfixed larynges in cadavers from persons aged 25 to 89 years. Larynges were intubated or extubated according to former conceptions of arytenoid subluxation, which assume that the arytenoid tip enters the lumen of the tracheal tube, or that a deflection of the arytenoid occurs during withdrawal of the endotracheal tube with the cuff of the tube only partially deflated. Also, manual attempts were carried out to subluxate the arytenoid cartilage. Subsequently after dissecting the left and right cricoarytenoid joint from each larynx, the morphologic changes induced experimentally were analyzed using gross microscopic and histologic methods. RESULTS: Within the scope of the experiment, it proved impossible to produce any subluxation of a cricoarytenoid joint. Histologic analysis revealed injuries of synovial folds, joint-surface impressions of the articular cartilage, and fractures in the area of the subchondral bone in some joints. CONCLUSIONS: Based on the morphologic results, it was concluded that intubation trauma of the cricoarytenoid joint does not cause subluxation per se, but rather that formation of a hemarthros or fractures of the joint bodies lead to fixation of the joint surfaces in an abnormal position. Subsequent ankylosis may occur. (+info)
Gastric pressure during emergency caesarean section under general anaesthesia.
Gastric pressure and volume were measured in 20 pregnant women during emergency Caesarean section under general anaesthesia with neuromuscular block. Mean gastric pressure was 11 (range 4-19) mm Hg and we can predict that 99% of women undergoing emergency Caesarean section with neuromuscular block are likely to have gastric pressures of less than 25 mm Hg (mean + 3 SD). This has implications for the amount of cricoid pressure required during induction of anaesthesia. Gastric pressure increased during delivery to 19 mm Hg and fundal pressure caused a gastric pressure of 65 mm Hg in one woman. Gastric pressure decreased significantly after delivery (P < 0.001) to 8 mm Hg. Although we measured large gastric volumes (mean 112 (range 20-350) ml), there was no correlation between gastric volume and gastric pressure. (+info)
Osteoarthritis in cricoarytenoid joint.
OBJECTIVE: Occurrence of osteoarthritis is a frequent event of limb joints in people over 40 years of age. The human cricoarytenoid joint is comparable with the joints of the limbs despite its structure and extracellular matrix composition. To date, little is known about the occurrence of osteoarthritis in the human cricoarytenoid joint. METHODS: Sixty-eight cricoarytenoid joints (42 male and 26 female, age 25-98 years) were analysed by means of histology, lectin histochemistry, immunohistochemistry as well as scanning and transmission electron microscopy. RESULTS: About 50% of the investigated cricoarytenoid joints aged over 40 years show degenerative changes in their joint surface structure at varying levels of intensity. The articular cartilage surface is fibrillated in some places and sometimes shows fissures. A demascing of collagen fibrils next to the joint surface and a loss of proteoglycans in the upper cartilage layers can be observed. Chondrocytes near the joint surface appear as voluminous chondrocyte clusters. The clusters and the superficial cartilage layer show a positive reaction to type VI collagen antibodies. The distribution patterns of lectins are completely changed in fibrillated cartilage areas. CONCLUSION: Degenerative alterations in diarthrodial joints resembling osteoarthritis can occur in the joints of the larynx. These structural changes of the articular cartilage are comparable to osteoarthritis of the limb joints. Osteoarthritis in the cricoarytenoid joint may lead to impaired movements of the arytenoid cartilages. Functionally the structural changes may lead to negative consequences during vocal production, such as impaired vocal quality and reduced vocal intensity. (+info)
Effect of cricoid pressure on insertion of and ventilation through the cuffed oropharyngeal airway.
We have assessed the effect of cricoid pressure on insertion of and ventilation through the cuffed oropharyngeal airway (COPA) in 53 patients, in a double-blind, randomized study. Two anaesthetists assessed adequacy of ventilation in anaesthetized and paralysed patients at the same time but using different methods. The first assessed ventilation clinically, by observing synchronized chest expansion with gentle manual ventilation and the second noted measurements of tidal volume (VT) and peak inspiratory pressure (PIP). Five mask ventilated breaths ('baseline') were assessed as above. Patients were then allocated randomly to receive cricoid pressure (group A, n = 28) or no cricoid pressure (group B, n = 25). Five further mask ventilated breaths ('after manoeuvre') were again assessed. A COPA was then inserted and five further breaths ('after COPA') were assessed. A COPA was inserted at the first attempt in all patients except for one in group A who required two attempts. COPA placement was difficult in one patient in group B who had a small distance between the incisor teeth. Ventilation was clinically 'adequate' in all patients except for one in the cricoid pressure group. There were no significant differences in measured VT or PIP between 'baseline' and 'after manoeuvre' breaths. Significant differences in VT and PIP were found after COPA insertion in the group that received cricoid pressure, with a mean decrease in VT of 108 ml (P = 0.0049) and a mean increase in PIP of 5.2 cm H2O (P = 0.0111). (+info)
Competence of the internal jugular vein valve is damaged by cannulation and catheterization of the internal jugular vein.
BACKGROUND: Experimental results suggest that the competence of the internal jugular vein (IJV) valve may be damaged when the IJV is cannulated for insertion of a central venous catheter. It has further been hypothesized that the risk of causing incompetence of the proximally located valve might be reduced by using a more distal site for venous cannulation. The present study evaluated these hypotheses in surgical patients. METHODS: Ninety-one patients without preexisting incompetence of the IJV valve were randomly assigned to undergo distal or proximal IJV cannulation (> or = 1 cm above or below the cricoid level, respectively). Color Doppler ultrasound was used to study whether new valvular incompetence was present during Valsalva maneuvers after insertion of a central venous catheter, immediately after removal of the catheter, and, in a subset of patients, several months after catheter removal, when compared with baseline findings before cannulation of the IJV. RESULTS: Incompetence of the IJV valve was frequently induced both by proximal and distal cannulation and catheterization of the IJV. Its incidence was higher after proximal than after distal cannulation (76% vs. 41%; P < 0.01) and tended to be so after removal of the catheter (47% vs. 28%; P = 0.07). Valvular incompetence persisting immediately after removal of the catheter did not recover within 8-27 months in most cases. CONCLUSIONS: Cannulation and catheterization of the IJV may cause persistent incompetence of the IJV valve. Choosing a more distal site for venous cannulation may slightly lower the risk of causing valvular incompetence but does not reliably avoid it. (+info)
Calcified vertical plate of the cricoid--a rare pitfall in the diagnosis of an oesophageal foreign body.
We present a case of rare pitfall in the diagnosis of an oesophageal foreign body due to the calcified vertical plate of the cricoid to highlight the need to be aware of this entity to avoid unnecessary morbidity. (+info)
Cricoid pressure applied after placement of laryngeal mask impedes subsequent fibreoptic tracheal intubation through mask.
We studied 70 patients to see if cricoid pressure applied after insertion of the laryngeal mask altered the success rate of tracheal intubation through the mask. After induction of anaesthesia and neuromuscular blockade, patients were randomly allocated to have either cricoid pressure (Group C) or sham pressure (Group S). The view of the glottis through the laryngeal mask was assessed before and after the test pressure, and tracheal intubation through the mask was attempted using a fibreoptic bronchoscope. The test pressure did not alter the view of the glottis in any patient in group S, whereas it narrowed the glottic aperture in 16 out of 35 patients in group C. The fibrescope was inserted into the trachea in all patients in group S and in 25 patients in group C. The success rate of tracheal intubation in group S (31 patients) was significantly higher than in group C (21 patients, P << 0.001; 95% CI for difference: 9-48%). The time for insertion of the fibrescope in group S (median (95% CI): 12 (11-12) s) was significantly faster than in group C (16 (14-17) s, P << 0.001; 95% CI for difference: 3-6 s), and the time for tracheal intubation in group S (16 (15-18) s) was significantly faster than in group C (22 (19-24) s, P < 0.0005; 95% CI for difference: 3-7 s). Cricoid pressure after insertion of the laryngeal mask makes tracheal intubation through the mask significantly more difficult. (+info)