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Tracheal Rings (tracheal + ring)
Selected AbstractsStylet Bend Angles and Tracheal Tube Passage Using a Straight-to-cuff ShapeACADEMIC EMERGENCY MEDICINE, Issue 12 2006Richard M. Levitan MD Abstract Objectives Malleable stylets improve maneuverability and control during tube insertion, but after passage through the vocal cords the stiffened tracheal tube may impinge on the tracheal rings, preventing passage. The goal of this study was to assess insertion difficulty with styletted tubes of different bend angles. Methods Tube passage was assessed with four different bend angles (25°, 35°, 45°, and 60°) using straight-to-cuff,shaped tubes. In two separate airway procedure classes, 16 operators in each class (32 total) placed randomly ordered styletted tubes of the different angles into eight cadavers (16 total). Operators subjectively graded the ease of tube passage as no resistance, some resistance, or impossible to advance. Results No resistance was reported in 69.1% (177/256) at 25°, in 63.7% (163/256) at 35°, in 39.4% (101/256) at 45°, and in 8.9% (22/256) at 60°. Tube passage was impossible in 2.3% of insertions (6/256) at 25°, in 3.5% (9/256) at 35°, in 11.3% (29/256) at 45°, and in 53.9% (138/256) at 60°. The odds ratios of impossible tube passage for 35°, 45°, and 60° vs. 25° were 1.52 (95% confidence interval [CI] = 0.55 to 4.16), 5.32 (95% CI = 2.22 to 12.71), and 48.72 (95% CI = 21.35 to 111.03), respectively. Conclusions Bend angles beyond 35° with straight-to-cuff styletted tracheal tubes increase the risk of difficult and impossible tube passage into the trachea. The authors did not compare different stylet stopping points, stylets of different stiffness, or tracheal tubes with different tip designs, all variables that can affect tube passage. [source] 1,8-Cineole induces relaxation in rat and guinea-pig airway smooth muscleJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2009Nilberto Robson Falcăo Nascimento Abstract Objectives 1,8-Cineole is a monoterpene with anti-inflammatory, vascular and intestinal smooth muscle relaxant activity. We have evaluated the potential bronchodilatatory activity of this compound. Methods 1,8-Cineole was tested against carbachol, histamine, K+ 80 mM and ovalbumin-induced bronchial contractions in Wistar rat or guinea-pig tissues. Some of the guinea-pigs had been previously sensitized with an intramuscular injection of 5% (w/v) ovalbumin/saline solution. Control animals received 0.3 ml saline. In separate experimental groups the response to 1,8-cineole (1,30 mg/kg), phenoterol (0.05,5 mg/kg) or vehicle (0.3% Tween in saline) was studied. Key findings 1,8-Cineole decreased, in vivo, rat bronchial resistance with similar efficacy as phenoterol (66.7 ± 3.2% vs 72.1 ± 5.3%). On the other hand, the maximal relaxant response to 1,8-cineole in carbachol-precontracted rat tracheas was 85.5 ± 5.7% (IC50 = 408.9 (328,5196) ,g/ml) compared with 80.2 ± 4.8% (IC50 = 5.1 (4.3,6.1) ,g/ml) with phenoterol. The addition of 1,8-cineole to guinea-pig tracheal rings tonically contracted with K+ 80 mM induced a concentration-related relaxation. The maximal relaxation elicited by 1,8-cineole was 113.6 ± 11.7% (IC50 127.0 (115.9,139.2) ,g/ml) compared with 129.7 ± 14.6% (IC50 0.13 (0.12,0.14) ,g/ml) achieved after phenoterol administration. In addition, the incubation of tracheal rings with 1,8-cineole (100, 300 or 1000 ,g/ml), 15 min before inducing phasic contractions with K+ 80 mM, decreased the maximal amplitude of the contraction by 31.6 ± 4.6, 75.7 ± 2.7 and 92.2 ± 1.5%, respectively. In another set of experiments, neither the maximal response nor the IC50 for the 1,8-cineole-induced relaxation were different between normal and ovalbumin-sensitized tissues. Moreover, the relaxation of bronchial rings contracted after exposure to 1 ,g/ml ovalbumin occurred at a faster rate in rings pre-incubated with 1,8-cineole when compared with rings pre-incubated with vehicle only (Tween 0.3%). Therefore, in the first minute after the antigen challenge, the tracheal tissue relaxed after the peak contraction by 6.5, 21.4 (P < 0.05 vs control) and 66.9% (P < 0.05 vs control) in the presence of 100, 300 or 1000 ,g/ml 1,8-cineole, respectively. Conclusions 1,8-Cineole relaxed rat and guinea-pig (nonsensitized and ovalbumin-sensitized) airway smooth muscle by a nonspecific mechanism. [source] Tracheal agenesis: management of the first 10 months of lifePEDIATRIC ANESTHESIA, Issue 9 2004S. Baroncini-Cornea MD Summary Tracheal agenesis is a potentially lethal congenital anomaly, appearing only at birth. We describe a newborn preterm infant who presented with immediate respiratory distress and no audible cry. There was almost complete tracheal agenesis with a very short segment of distal trachea (only two tracheal rings) arising from the anterior wall of the esophagus, before dividing into the mainstem bronchi. The anomaly was unsuspected prenatally, as the scan showed pyloric atresia and complex congenital cardiac disease. Despite the patient's difficult course, with correction of the rare-associated malformations (cardiac and gastrointestinal tract anomalies), the fact that the child is lively and neurologically normal for her age, requires that we now consider the patency of the airway and the possibility of surgical correction, in accordance with a good quality of life. [source] Correlation of tracheal smooth muscle function with structure and protein expression during early development,PEDIATRIC PULMONOLOGY, Issue 5 2007Aaron B. Cullen MD Abstract With increased survival of premature infants, understanding the impact of development on airway function and structure is imperative. Airway smooth muscle plays a primary role in the modulation of airway function. The purpose of this study is to correlate the functional maturation of airway smooth muscle during the perinatal period with structural alterations at the cellular, ultrastructural, and molecular levels. Length-tension and dose-response analyses were performed on tracheal rings acquired from preterm and term newborn lambs. Subsequent structural analyses included isolated airway smooth muscle cell length, electron microscopy, and myosin heavy chain isoform expression measurements. Functionally the compliance, contractility, and agonist sensitivity of the tracheal rings matured during preterm to term development. Structurally, isolated cell lengths and electron microscopic ultrastructure were not significantly altered during perinatal development. However, expression of myosin heavy chain isoforms increased significantly across the age range analyzed, correlating with the maturational increase in smooth muscle contractility. In conclusion, the developmental alterations in tracheal function appear due, in part, to enhanced smooth muscle myosin heavy chain expression. Pediatr Pulmonol. 2007; 42:421,432. © 2007 Wiley-Liss, Inc. [source] Pharmacology and immunological actions of a herbal medicine ASHMITM on allergic asthmaPHYTOTHERAPY RESEARCH, Issue 7 2010Tengfei Zhang Abstract Allergic asthma is a chronic and progressive inflammatory disease for which there is no satisfactory treatment. Studies reported tolerability and efficacy of an anti-asthma herbal medicine intervention (ASHMI) for asthma patients, developed from traditional Chinese medicine. To investigate the pharmacological actions of ASHMI on early- and late-phase airway responses (EAR and LAR), Ovalbumin (OVA)-sensitized mice received 6 weeks of ASHMI treatment beginning 24,h following the first intratracheal OVA challenge. EAR were determined 30,min following the fourth challenge and LAR 48,h following the last challenge. ASHMI effects on cytokine secretion, murine tracheal ring contraction and human bronchial smooth muscle cell prostaglandin (PG) production were also determined. ASHMI abolished EAR, which was associated with significantly reduced histamine, leukotriene C4, and OVA-specific IgE levels, as well as LAR, which was associated with significantly reduced bronchoalveolar lavage fluid (BALF) eosinophils, decreased airway remodeling, and lower Th2 cytokine levels in BALF and splenocyte cultures. Furthermore, ASHMI inhibited contraction of murine tracheal rings and increased production of the potent smooth muscle relaxer PGI2. ASHMI abrogation of allergic airway responses is associated with broad effects on asthma pathological mechanisms. Copyright © 2009 John Wiley & Sons, Ltd. [source] Awake fibrecapnic intubation: a novel technique for intubation in head and neck cancer patients with a difficult airway,ANAESTHESIA, Issue 5 2006J. M. Huitink Summary Awake fibreoptic intubation is the gold standard for difficult airway management but failures are reported in the literature in up to 13% of cases. In case of failure, a tracheotomy is often indicated. We describe a novel technique for intubation in head and neck cancer patients with a difficult airway that we call awake fibrecapnic intubation. The aim of this study was to investigate the feasibility of this technique. We studied prospectively 15 consecutive intubations in head and neck cancer patients before diagnostic or therapeutic surgical procedures. After topical anaesthesia, a fibrescope was introduced into the pharynx. Spontaneous respiration was maintained in all patients. Through the suction channel of the fibrescope a special suction catheter was advanced into the airway for carbon dioxide measurements. When four capnograms were obtained, the fibrescope was railroaded over the catheter and after identification of tracheal rings, a tracheal tube was placed. Tracheal intubation was successful in all patients without bleeding or complications, with a median (range) time to intubation of 3 (2,15) min. Identification of the vocal cords and glottis was difficult in four patients due to extensive anatomical abnormalities or poor visibility; even in these patients, a capnogram was obtained within 4 s. [source] In vitro tracheal hyperresponsiveness to muscarinic receptor stimulation by carbachol in a rat model of bleomycin-induced pulmonary fibrosisAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 3 2006J. Barrio Summary 1 Bleomycin-induced lung injury is widely used as an experimental model to investigate the pathophysiology of pulmonary fibrosis but the alterations in the pharmacological responsiveness of airways isolated from bleomycin-exposed animals has been scarcely investigated. The aim of this study was to examine the in vitro tracheal responses to muscarinic receptor stimulation with carbachol in a rat bleomycin model. 2 Concentration,response curves to carbachol (10 nm to 0.1 mm) were obtained in tracheal rings isolated from Sprague,Dawley rats 14 days after endotracheal bleomycin or saline. The intracellular calcium signal in response to carbachol (10 ,m) was measured by epifluorescence microscopy using fura-2 in primary cultures of tracheal smooth muscle cells from bleomycin- and saline-exposed rats. Circulating plasma tumour necrosis factor (TNF)- ,/interleukin (IL)-1, levels were measured by enzyme-linked immunosorbent assay. 3 Maximal contraction in response to carbachol was significantly greater in tracheal rings from bleomycin-exposed rats compared with controls (15.8 ± 1.3 mN vs. 11.8 ± 1.4 mN; n = 19, P < 0.05). 4 Carbachol (10 ,m) elicited a transient increase of intracellular calcium with greater increment in tracheal smooth muscle cells from bleomycin-exposed rats compared with controls (372 ± 42 nmvs. 176 ± 20 nm; n = 7, P < 0.01). 5 Circulating plasma levels of TNF- ,/IL-1, were augmented in bleomycin-exposed rats compared with controls. Tissue incubation with TNF- , (100 ng ml,1)/IL-1, (10 ng ml,1) increased in vitro tracheal responsiveness to carbachol. 6 In conclusion, tracheal contraction in response to muscarinic receptor stimulation with carbachol was increased in bleomycin-exposed rats. This in vitro cholinergic hyperresponsiveness may be related to the augmented levels of inflammatory cytokines in bleomycin-exposed rats. [source] Multitarget Drugs: Synthesis and Preliminary Pharmacological Characterization of Zileuton Analogues Endowed with Dual 5-LO Inhibitor and NO-Dependent ActivitiesCHEMMEDCHEM, Issue 9 2010Donatella Boschi Prof. Multitarget drugs: The title compounds represent the first class of dual-action drugs with 5-LO inhibition and NO-dependent activities. They block leukotriene B4 production with potencies near that of zileuton and are capable of relaxing rat tracheal rings and rat aorta strips through a NO-mediated mechanism. Some compounds also show anti-inflammatory activity in carrageenan- induced rat paw edema. [source] Role of 5-HT2A, 5-HT4 and 5-HT7 receptors in the antigen-induced airway hyperresponsiveness in guinea-pigsCLINICAL & EXPERIMENTAL ALLERGY, Issue 2 2010P. Segura Summary Background A possible role of 5-hydroxytryptamine (5-HT) in the origin of antigen-induced airway hyperresponsiveness (AI-AHR) has been scarcely investigated. Objective To explore the participation of different 5-HT receptors in the development of AI-AHR in guinea-pigs. Methods Lung resistance was measured in anaesthetized guinea-pigs sensitized to ovalbumin (OVA). Dose,response curves to intravenous (i.v.) acetylcholine (ACh) were performed before and 1 h after antigenic challenge and expressed as the 200% provocative dose (PD200). Organ bath experiments, confocal microscopy and RT-PCR were additionally used. The 5-HT content in lung homogenates was measured by HPLC. Results Antigenic challenge significantly decreased PD200, indicating the development of AI-AHR. This hyperresponsiveness was abolished by a combination of methiothepin (5-HT1/5-HT2/5-HT5/5-HT6/5-HT7 receptors antagonist) and tropisetron (5-HT3/5-HT4 antagonist). Other 5-HT receptor antagonists showed three different patterns of response. Firstly, WAY100135 (5-HT1A antagonist) and ondansetron (5-HT3 antagonist) did not modify the AI-AHR. Secondly, SB269970 (5-HT7 antagonist), GR113808 (5-HT4 antagonist), tropisetron or methiothepin abolished the AI-AHR. Thirdly, ketanserin (5-HT2A antagonist) produced airway hyporresponsiveness. Animals with bilateral vagotomy did not develop AI-AHR. Experiments in tracheal rings showed that pre-incubation with LP44 or cisapride (agonists of 5-HT7 and 5-HT4 receptors, respectively) induced a significant increase of the cholinergic contractile response to the electrical field stimulation. In sensitized lung parenchyma strips, ketanserin diminished the contractile responses to ACh. Sensitization was associated with a ninefold increase in the 5-HT content of lung homogenates. Confocal microscopy showed that sensitization enhanced the immunolabelling and co-localization of nicotinic receptor and 5-HT in airway epithelium, probably located in pulmonary neuroendocrine cells (PNECs). RT-PCR demonstrated that neither sensitization nor antigen challenge modified the 5-HT2A receptor mRNA levels. Conclusions Our results suggested that 5-HT was involved in the development of AI-AHR to ACh in guinea-pigs. Specifically, 5-HT2A, 5-HT4 and 5-HT7 receptors seem to be particularly involved in this phenomenon. Participation of 5-HT might probably be favoured by the enhancement of the PNECs 5-HT content observed after sensitization. Cite this as: P. Segura, M. H. Vargas, G. Córdoba-Rodríguez, J. Chávez, J. L. Arreola, P. Campos-Bedolla, V. Ruiz, L. M. García-Hernández, C. Méndez and L. M. Montańo, Clinical & Experimental Allergy, 2010 (40) 327, 338. [source] Inhibitory effect of 1,8-cineole on guinea-pig airway challenged with ovalbumin involves a preferential action on electromechanical couplingCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2009Vasco PD Bastos Summary 11,8-Cineole is a terpenoid constituent of essential oils with anti-inflammatory properties. It reduces the neural excitability, functions as an antinociceptive agent and has myorelaxant actions in guinea-pig airways. The aim of the present study was to investigate the mechanism underlying the myorelaxant effects of 1,8-cineole in guinea-pig isolated trachea from either naďve guinea-pigs or ovalbumin (OVA)-sensitized animals subjected to antigenic challenge. 2Isometric recordings were made of the tone of isolated tracheal rings. Rings with an intact epithelium relaxed beyond basal tone in the presence of 1,8-cineole (6.5 × 10,6 to 2 × 10,2 mol/L) in a concentration-dependent manner (P < 0.001, anova) with a pD2 value of 2.23 (95% confidence interval 2.10,2.37). Removal of the epithelium or pretreatment of intact tissue for 15 min with 50 µmol/L NG -nitro- l -arginine methyl ester, 5 mmol/L tetraethylammonium, 0.5 µmol/L tetrodotoxin or 5 µmol/L propranolol did not alter the potency (pD2) or the maximal myorelaxant effect (Emax) of 1,8-cineole. 31,8-Cineole also significantly decreased the Schultz-Dale contraction induced by OVA, mainly in preparations from OVA-sensitized animals submitted to antigen challenge. 1,8-Cineole decreased tracheal hyperresponsiveness to KCl and carbachol caused by antigen challenge and almost abolished the concentration,response curves to KCl, whereas it had little effect on the concentration,response curves to carbachol. Under Ca2+ -free conditions and in the presence of 10,4 mol/L acetylcholine, neither 1,8-cineole (6.5 × 10,3 mol/L) nor verapamil (1 × 10,5 mol/L) affected Ca2+ -induced contractions, but they almost abolished Ba2+ -induced contractions. 4In conclusion, the findings of the present study show that 1,8-cineole is a tracheal myorelaxant that acts preferentially on contractile responses elicited electromechanically. [source] ROLE OF EXTRACELLULAR Na+, Ca2+ -ACTIVATED Cl - CHANNELS AND BK CHANNELS IN THE CONTRACTION OF Ca2+ STORE-DEPLETED TRACHEAL SMOOTH MUSCLECLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2009Catalina Romero-Méndez SUMMARY 1In the present study, we investigated the series of events involved in the contraction of tracheal smooth muscle induced by the re-addition of Ca2+ in an in vitro experimental model in which Ca2+ stores had been depleted and their refilling had been blocked by thapsigargin. 2Mean (±SEM) contraction was diminished by: (i) inhibitors of store-operated calcium channels (SOCC), namely 100 µmol/L SKF-96365 and 100 µmol/L 1-(2-trifluoromethylphenyl) imidazole (to 66.3 ± 4.4 and 41.3 ± 5.2% of control, respectively); (ii) inhibitors of voltage-gated Ca2+ channels CaV1.2 channels, namely 1 µmol/L nifedipine and 10 µmol/L verapamil (to 86.2 ± 3.4 and 76.9 ± 5.9% of control, respectively); and (iii) 20 µmol/L niflumic acid, a non-selective inhibitor of Ca2+ -dependent Cl, channels (to 41.1 ± 9.8% of control). In contrast, contraction was increased 2.3-fold by 100 nmol/L iberiotoxin, a blocker of the large-conductance Ca2+ -activated K+ (BK) channels. 3Furthermore, contraction was significantly inhibited when Na+ in the bathing solution was replaced by N -methyl,d -glucamine (NMDG+) to 39.9 ± 7.2% of control, but not when it was replaced by Li+ (114.5 ± 24.4% of control). In addition, when Na+ had been replaced by NMDG+, contractions were further inhibited by both nifedipine and niflumic acid (to 3.0 ± 1.8 and 24.4 ± 8.1% of control, respectively). Nifedipine also reduced contractions when Na+ had been replaced by Li+ (to 10.7 ± 3.4% to control), the niflumic acid had no effect (116.0 ± 4.5% of control). 4In conclusion, the data of the present study demonstrate the roles of SOCC, BK channels and CaV1.2 channels in the contractions induced by the re-addition of Ca2+ to the solution bathing guinea-pig tracheal rings under conditions of Ca2+ -depleted sacroplasmic reticulum and inhibition of sarcoplasmic/endoplasmic reticulum calcium ATPase. The contractions were highly dependent on extracellular Na+, suggesting a role for SOCC in mediating the Na+ influx. [source] | ||||||||||||||||||||||