Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Airway

  • asthmatic airway
  • bronchial airway
  • cf airway
  • classic laryngeal mask airway
  • conducting airway
  • difficult airway
  • distal airway
  • human airway
  • large airway
  • laryngeal mask airway
  • lower airway
  • lung airway
  • mask airway
  • nasal airway
  • patent airway
  • pediatric airway
  • peripheral airway
  • proseal laryngeal mask airway
  • proximal airway
  • respiratory airway
  • secure airway
  • small airway
  • supraglottic airway
  • upper airway

  • Terms modified by Airway

  • airway abnormality
  • airway anaesthesia
  • airway anatomy
  • airway assessment
  • airway cell
  • airway clearance
  • airway closure
  • airway complications
  • airway compromise
  • airway device
  • airway dimension
  • airway disease
  • airway disorders
  • airway dysfunction
  • airway endoscopy
  • airway eosinophilia
  • airway epithelial cell
  • airway epithelium
  • airway fibrosis
  • airway function
  • airway hyper-responsiveness
  • airway hyperresponsiveness
  • airway infection
  • airway inflammation
  • airway inflammatory disease
  • airway injury
  • airway intervention
  • airway lesion
  • airway lumen
  • airway management
  • airway mucus
  • airway narrowing
  • airway obstruction
  • airway occlusion
  • airway patency
  • airway pressure
  • airway pressure therapy
  • airway pressure ventilation
  • airway problem
  • airway reactivity
  • airway remodeling
  • airway remodelling
  • airway resistance
  • airway resistance syndrome
  • airway response
  • airway responsiveness
  • airway secretion
  • airway smooth muscle
  • airway smooth muscle cell
  • airway smooth muscle contraction
  • airway space
  • airway stenosis
  • airway structure
  • airway surgery
  • airway symptom
  • airway tissue

  • Selected Abstracts


    Darren J Fernandes
    SUMMARY 1.,Airway smooth muscle (ASM) has recently been termed the ,frustrated' cell of the lung given that contraction of ASM has no proven useful physiological function in adults and yet is indelibly associated with pathological conditions by virtue of its unwanted airflow-limiting actions in asthma. In contrast, pulmonary vascular smooth muscle contraction plays an essential role in the control of blood flow through the lung. 2.,Little is known of the differences in phenotype between human ASM and pulmonary vascular smooth muscle (VSM) tissues, but differences in contractile protein and transcription factor expression and regulation of contractile protein promoter activity have been documented. Similarly, the embryological signals in mice required for differentiation of ASM versus pulmonary VSM are distinct. 3.,Bronchoconstriction in asthma is currently treated with ,2 -adrenoceptor agonists, which relax contracted ASM cells. An additional approach may be to use gene therapy to render ASM unable to contract (via disruption of their contractile apparatus organization). 4.,Application of ASM-specific gene therapies would rely on minimal actions on other lung smooth muscle tissues, including pulmonary and bronchial vascular smooth muscle. The combination of mRNA analysis of laser-captured microdissected tissue with in situ immunohistochemical staining for protein should be very useful in terms of being able to characterize definitively the differences in mRNA and protein expression between the smooth muscle species of the lung. Any discovery of an ASM-selective target could provide a novel lead for ASM-directed anti-asthma therapy. [source]

    Randomized comparison of the SLIPA (Streamlined Liner of the Pharynx Airway) and the SS-LM (Soft Seal Laryngeal Mask) by medical students

    Cindy Hein
    Abstract Objective:, The aim of the study was to compare the Streamlined Liner of the Pharynx Airway (SLIPA; Hudson RCI), a new supraglottic airway device, with the Soft Seal Laryngeal Mask (SS-LM; Portex) when used by novices. Methods:, Thirty-six medical students with no previous airway experience, received manikin training in the use of the SLIPA and the SS-LM. Once proficient, the students inserted each device in randomized sequence, in two separate patients in the operating theatre. Only two insertion attempts per patient were allowed. Students were assessed in terms of: device preference; success or failure; success at first attempt and time to ventilation. Results:, Sixty-seven per cent of the students preferred to use the SLIPA (95% confidence interval 49,81%). The SLIPA was successfully inserted (one or two attempts) in 94% of patients (34/36) and the SS-LM in 89% (32/36) (P = 0.39). First attempt success rates were 83% (30/36) and 67% (24/36) in the SLIPA and SS-LM, respectively (P = 0.10). Median time to ventilation was shorter with the SLIPA (40.6 s) than with the SS-LM (66.9 s) when it was the first device used (P = 0.004), but times were similar when inserting the second device (43.8 s vs 42.9 s) (P = 0.75). Conclusions:, In the present study novice users demonstrated high success rates with both devices. The SLIPA group achieved shorter times to ventilation when it was the first device they inserted, which might prove to be of clinical significance, particularly in resuscitation attempts. Although the Laryngeal Mask has gained wide recognition for use by both novice users and as a rescue airway in failed intubation, the data presented here suggest that the SLIPA might also prove useful in these areas. [source]

    Surgical Stent Fabrication for Unilateral Nasal Obstruction of the Anterior Portion of the Nasal Airway

    Fong Wong BSD
    Abstract A description is given of the indication and technical steps for fabricating a unilateral nasal stent to maintain patency of the nasal passage after surgical opening of an obstruction in a pediatric case. The methodology uses a two-step impression of the contralateral unobstructed naris and exterior valve region to generate a two-piece injection mold. The mold is used to fabricate a soft silicone-based anatomical stent. It supports an intranasal skin graft that was placed to reduce the risk of granulation. [source]

    Alcohol Primes the Airway for Increased Interleukin-13 Signaling

    ALCOHOLISM, Issue 3 2009
    Patrick O. Mitchell
    Background:, Using an experimental model of airway fibrosis following lung transplantation, we recently showed that chronic alcohol ingestion by donor rats amplifies airway fibrosis in the recipient. Associated with alcohol-mediated amplification of airway fibrosis is increased transforming growth factor ,-1(TGF,1) and ,-smooth muscle actin expression. Other studies have shown that interleukin-13 (IL-13) modulates TGF,1 signaling during experimentally-induced airway fibrosis. Therefore, we hypothesized that IL-13 is a component of alcohol-mediated amplification of pro-fibrotic mediators in the alcoholic lung. Methods:, To test this hypothesis, we analyzed tracheal epithelial cells and type II alveolar cells from control- or alcohol-fed rats, alcohol-treated mouse lung fibroblasts, and human bronchial epithelial cells in vitro for expression of various components of the IL-13 signaling pathway. Signaling via the IL-13 pathway was assessed by measuring levels of phosphorylated signal transducers and activators of transcription-6 (STAT6). In addition, we performed heterotopic tracheal transplantation using control-fed and alcohol-fed donor rats and analyzed tracheal allografts for expression of components of the IL-13 signaling pathway by RT-PCR and immunocytochemical analyses. Results:, Interleukin-13 expression was detected in type II alveolar epithelial cells and human bronchial epithelial cells, but not in lung fibroblasts. IL-13 expression was decreased in whole lung and type II cells in response to alcohol exposure. In all cell types analyzed, expression of IL-13 signaling receptor (IL-13R,1) mRNA was markedly increased. In contrast, mRNA and protein expression of the IL-13 decoy receptor (IL-13R,2) were decreased in all cells analyzed. Exposure to alcohol also increased STAT6 phosphorylation in response to IL-13 and lipopolysaccharide. Conclusions:, Data from multiple cell types in the pulmonary system suggest that IL-13 and its receptors play a role in alcohol-mediated activation of pro-fibrotic pathways. Taken together, these data suggest that alcohol primes the airway for increased IL-13 signaling and subsequent tissue remodeling upon injury such as transplantation. [source]

    Airway wall geometry in asthma and nonasthmatic eosinophilic bronchitis

    ALLERGY, Issue 6 2009
    S. Siddiqui
    Background:, Variable airflow obstruction and airway hyperresponsiveness (AHR) are features of asthma, which are absent in nonasthmatic eosinophilic bronchitis (EB). Airway remodelling is characteristic of both conditions suggesting that remodelling and airway dysfunction are disassociated, but whether the airway geometry differs between asthma and nonasthmatic EB is uncertain. Methods:, We assessed airway geometry by computed tomography (CT) imaging in asthma vs EB. A total of 12 subjects with mild,moderate asthma, 14 subjects with refractory asthma, 10 subjects with EB and 11 healthy volunteers were recruited. Subjects had a narrow collimation (0.75 mm) CT scan from the aortic arch to the carina to capture the right upper lobe apical segmental bronchus (RB1). In subjects with asthma and EB, CT scans were performed before and after a 2-week course of oral prednisolone (0.5 mg/kg). Results:, Mild,moderate and refractory asthma were associated with RB1 wall thickening in contrast to subjects with nonasthmatic EB who had maintained RB1 patency without wall thickening [mean (SD) % wall area and luminal area mild-t0-moderate asthma 67.7 (7.3)% and 6.6 (2.8) mm2/m2, refractory asthma 67.3 (5.6)% and 6.7 (3.4) mm2/m2, healthy control group 59.7 (6.3)% and 8.7 (3.8) mm2/m2, EB 61.4 (7.8)% and 11.1 (4.6) mm2/m2 respectively; P < 0.05]. Airway wall thickening of non-RB1 airways generation three to six was a feature of asthma only. There was no change in airway geometry of RB1 after prednisolone. Proximal airway wall thickening was associated with AHR in asthma (r = ,0.56; P = 0.02). Conclusions:, Maintained airway patency in EB may protect against the development of AHR, whereas airway wall thickening may promote AHR in asthma. [source]

    Resistive load of laryngeal mask airway and proseal laryngeal mask airway in mechanically ventilated patients

    G. Natalini
    Background:, The ProSeal Laryngeal Mask Airway (PLMA) ventilation tube is narrower and shorter than the standard Laryngeal Mask Airway (LMA) and is without the vertical bars at the end of the tube. In this randomized, crossover study, PLMA and LMA resistances were compared. Methods:, Respiratory mechanics was calculated in 26 anesthetized, mechanically ventilated patients with both LMA and PLMA. The laryngeal mask positioning was fiberoptically evaluated. Differences in the respiratory mechanics of the LMA and the PLMA were attributed to the differences between the laryngeal masks. Results:, In the total study population the airway resistance was 1.5 ± 2.6 hPa.l,1.s,1 (P = 0.005) higher with the PLMA than with the LMA. During the PLMA use, the peak expiratory flow reduced by 0.02 ± 0.05 l min,1 (P = 0.046), the expiratory resistance increased by 0.6 ± 1.3 hPa.l,1.s,1 (P = 0.022), and the time constant of respiratory system lengthened by 0.09 ± 0.18 s (P = 0.023). These differences doubled when the LMA was better positioned than the PLMA, whereas they disappeared when the PLMA was positioned better than the LMA. Conclusions:, The standard LMA offers a lower resistive load than the PLMA. Moreover, the fitting between the laryngeal masks and the larynx, as fiberoptically evaluated, plays a major role in determining the resistive properties of these devices. [source]

    Prevention of tracheal tube dislodgement and provision for reintubation during removal of Laryngeal Mask Airway

    Rajeev SharmaArticle first published online: 6 JAN 2010
    No abstract is available for this article. [source]

    ClassicTM Laryngeal Mask Airway in cardiac pediatric surgery

    Elena Miranda
    No abstract is available for this article. [source]

    The reliability of endtidal CO2 in spontaneously breathing children during anaesthesia with Laryngeal Mask AirwayTM, low flow, sevoflurane and caudal epidural

    Background: Noninvasive devices for monitoring endtidal CO2 (PECO2) are in common use in paediatric anaesthesia. Questions have been raised concerning the reliability of these devices in spontaneous breathing children during surgery. Our anaesthetic technique for elective infraumbilical surgery consists of spontaneous breathing through a Laryngeal Mask Airway (LMATM), low fresh gas flow, sevoflurane and a caudal epidural. We wanted to compare PECO2 and arterial CO2 (PaCO2) during surgery. Methods: Twenty children, aged 1,6 years, scheduled for infraumbilical surgery, were studied and one arterial sample was taken 45 min after induction of anaesthesia. PECO2, inspiratory PCO2, oxygen saturation, heart rate, respiratory rate, mean arterial blood pressure and expiratory sevoflurane concentration were measured every 5 min. The respiratory and circulatory parameters were stable during surgery. Results: The mean PaCO2 , PECO2 difference was 0.15 (0.16) kPa [1.1 (1.2 mmHg)]. Conclusions: PECO2 is a good indicator of PaCO2 in our anaesthetic setting. [source]

    Use of the Laryngeal Mask AirwayTM in mucopolysaccharidoses

    No abstract is available for this article. [source]

    Commentary to "The Difficult Airway" Resident Portfolio

    Debra Perina MD
    No abstract is available for this article. [source]

    Rapid Sequence Intubation & Rapid Sequence Airway

    William G. Fernandez MD
    No abstract is available for this article. [source]

    Reconstruction and Morphometric Analysis of the Nasal Airway of the Dog (Canis familiaris) and Implications Regarding Olfactory Airflow

    Brent A. Craven
    Abstract The canine nasal airway is an impressively complex anatomical structure, having many functional roles. The complicated branching and intricate scrollwork of the nasal conchae provide large surface area for heat, moisture, and odorant transfer. Of the previous anatomical studies of the canine nasal airway, none have included a detailed rendering of the maxilloturbinate and ethmoidal regions of the nose. Here, we present a high-resolution view of the nasal airway of a large dog, using magnetic resonance imaging scans. Representative airway sections are shown, and a three-dimensional surface model of the airway is reconstructed from the image data. The resulting anatomic structure and detailed morphometric data of the airway provide insight into the functional nature of canine olfaction. A complex airway network is revealed, wherein the branched maxilloturbinate and ethmoturbinate scrolls appear structurally distinct. This is quantitatively confirmed by considering the fractal dimension of each airway, which shows that the maxilloturbinate airways are more highly contorted than the ethmoidal airways. Furthermore, surface areas of the maxilloturbinate and ethmoidal airways are shown to be much different, despite having analogous physiological functions. Functionally, the dorsal meatus of the canine nasal airway is shown to be a bypass for odorant-bearing inspired air around the complicated maxilloturbinate during sniffing for olfaction. Finally, nondimensional analysis is used to show that the airflow within both the maxilloturbinate and ethmoturbinate regions must be laminar. This work has direct relevance to biomimetic sniffer design, chemical trace detector development, intranasal drug delivery, and inhalation toxicology. Anat Rec, 290:1325,1340, 2007. © 2007 Wiley-Liss, Inc. [source]

    Litigation related to airway and respiratory complications of anaesthesia: an analysis of claims against the NHS in England 1995,2007

    ANAESTHESIA, Issue 6 2010
    T. M. Cook
    Summary Claims notified to the NHS Litigation Authority in England between 1995 and 2007 and filed under anaesthesia were analysed to explore patterns of injury and cost related to airway or respiratory events. Of 841 interpretable claims the final dataset contained 96 claims of dental damage, 67 airway-related claims and 24 respiratory claims. Claims of dental damage contributed a numerically important (11%), but financially modest (0.5%) proportion of claims. These claims predominantly described injury during tracheal intubation or extubation; a minority associated with electroconvulsive therapy led to substantial cost per claim. The total cost of (non-dental) airway claims was £4.9 million (84% closed, median cost £30 000) and that of respiratory claims was £3.3 million (81% closed, median £27 000). Airway and respiratory claims account for 12% of anaesthesia-related claims, 53% of deaths, 27% of cost and ten of the 50 most expensive claims in the dataset. Airway claims most frequently described events at induction of anaesthesia, involved airway management with a tracheal tube and typically led to hypoxia and patient death or brain injury. Airway trauma accounted for one third of airway claims and these included deaths from mediastinal injury at intubation. Pulmonary aspiration and tube misplacement, including oesophageal intubation, led to several claims. Among respiratory claims, ventilation problems, combined with hypoxia, were an important source of claims. Although limited clinical details hamper analysis, the data suggest that most airway and respiratory-related claims arise from sentinel events. The absence of clinical detail and denominators limit opportunities to learn from such events; much more could be learnt from a closed claim or sentinel event analysis scheme. [source]

    Tracheal intubation and alternative airway management devices used by healthcare professionals with different level of pre-existing skills: a manikin study,

    ANAESTHESIA, Issue 5 2009
    B. M. Wahlen
    Summary The classic Laryngeal Mask Airway (cLMAÔ), ProSeal Laryngeal Mask Airway (PLMAÔ), Intubating Laryngeal Mask AirwayÔ (ILMAÔ), Combitube (CTÔ), Laryngeal Tube (LTÔ) and tracheal intubation (TI) were compared in a manikin study. Nurses, anaesthetic nurses, paramedics, physicians and anaesthetists inserted the devices three times in a randomised sequence. Time taken for successful insertion, success rates and ease of insertion were evaluated. Anaesthetists performed tracheal intubation significantly faster than other healthcare professionals (p < 0.05). Insertion times for the cLMA, PLMA, LT and CT were not significantly different between the groups. Insertion of the CT, ILMA and TI was associated with a significant learning effect in all groups. This was not observed with the cLMA, PLMA or LT. All non-anaesthetists were able to insert the cLMA, PLMA and LT within two attempts with a > 90% success rate on the first attempt. The ILMA and TI were the only devices where more than one subject experienced some difficulty in insertion. The cLMA, PLMA and LT should be evaluated for use in situations where only limited airway training is possible. [source]

    An evaluation of the PAxpress Pharyngeal Airway

    ANAESTHESIA, Issue 2 2003
    Article first published online: 23 SEP 200
    No abstract is available for this article. [source]

    Airway epithelium-derived transforming growth factor-, is a regulator of fibroblast proliferation in both fibrotic and normal subjects

    K. E. Hostettler
    Summary Background In the healthy lung, airway epithelial cells (AEC) regulate fibroblast proliferation through release of soluble factors, such as prostaglandins and proteins. Fibroproliferative diseases and airway remodelling may result from an inadequate generation of suppressive factors by AEC or the inability of fibroblasts to respond to them appropriately. Objective The aim of this study was to study the effect of primary human AEC on the proliferation of fibroblasts obtained from healthy and fibrotic lungs in an interactive cell culture model. Results Conditioned medium (CM) from 14 out of 16 AEC lines significantly inhibited proliferation of normal human lung fibroblasts by 51.2±6.0%. The proliferation of fibroblasts derived from patients with lung fibrosis was equally inhibited by CM of AEC. The inhibitory effect of AEC-CM was completely reversed when fibroblasts were pre-incubated with 2.5 ,m indomethacin. Furthermore, primary human AEC, but not fibroblasts, secrete TGF-,, and the inhibitory effect of the AEC-CM was blocked by neutralizing anti-TGF-, antibodies. Conclusion These results demonstrate that AEC actively inhibit the proliferation of both normal and fibrotic fibroblasts via TGF-,, which induces the prostaglandin E2 synthesis in fibroblasts. The data indicate that proliferative lung diseases may be treated using the epithelial cell as the target of medication. [source]

    Airway remodelling in asthma: models and supermodels?

    H. H. Kariyawasam
    First page of article [source]

    Studying the Gendering of Organizational Culture Over Time: Concerns, Issues and Strategies

    Albert J. Mills
    Beginning with the premise that ,organizational culture' is a useful heuristic for the study of gender at work, this article focuses on the problem of studying the culture of organizations over time, setting out to demonstrate how the social construction of corporate history has, until now, lent itself to gendered notions of business practices. Arguing that history itself is but one of a series of discourses about the world, the article outlines a feminist strategy for the study of organizational culture over time that includes: (i) feminist historiography as history written from a feminist point of view; (ii) a commitment to the notion of history as discourse rooted in the present; (iii) a view of women's rights development as a paradoxical process of progress and regress; (iv) a gender focus approach that studies the impact of discrimination on the social construction of masculinity/femininity and sexual preference; and (v) an approach that is sensitive to the contextualization of gender. British Airways is used as a case study to illustrate some of the problems of historic re/construction and feminist historiography. [source]

    Manipulating Rules, Contesting Solutions: Europeanization and the Politics of Restructuring Olympic Airways1

    Kevin Featherstone
    In recent years much debate has been generated over the reshaping of the European airline industry and the restructuring of many of the heavily indebted national flag-carriers across the European Union. The European Commission has sought to orchestrate this reform process by the gradual break up of monopolies in air travel and its associated services and a much tighter policing of state aid practices. The EU's liberalizing agenda in air transport, however, has met with strong domestic opposition in the member states. Nowhere else has the resistance to reform been stronger than in Greece, where for a decade successive attempts to restructure or privatize Olympic Airways have yielded very limited success. By focusing, in particular, on the initiative of the Greek government in 2003 to create a new ,Olympic Airlines', the article examines how domestic pressures prompted the Greek government to shift away from cooperation with the Commission and invite conflict. The Greek government lost an ECJ case and both Athens and the Commission were left with a sub-optimal outcome. By linking the narrative to the conceptual literature on Europeanization and compliance, the article addresses a number of themes including: the contestation of European competition rules and the ability of national governments to manipulate them, policy entrepreneurship and complex problem-solving, as well as the Commission's role as a stimulus, but potentially also an obstacle to domestic reform. [source]

    Does asthma control correlate with quality of life related to upper and lower airways?

    ALLERGY, Issue 6 2009
    A real life study
    Background:, The goal of asthma therapy is to achieve an optimal level of disease control, but the relationship between asthma control, impact of comorbid rhinitis and health related quality of life (HRQoL) in real life remains unexplored. Objective:, The aims of this real life study were to evaluate asthma control, the impact of asthma (with and without rhinitis) on HRQoL, the relationship between asthma control and HRQoL, and the role of rhinitis on asthma control and HRQoL. Methods:, 122 asthma patients completed the Asthma Control Test, Rhinitis Symptoms score (T5SS) and RHINASTHMA. Results:, Asthma control was unsatisfactory (44.27% of uncontrolled patients), as well as HRQoL. Controlled patients controlled showed significantly lower scores in all the RHINASTHMA domains compared to uncontrolled. Irrespective of their level of control, patients with rhinitis symptoms showed worse HRQoL in Upper Airways (UA) (P < 0.0001), Lower Airways (LA) (P < 0.001), and Global Summary (GS) (P < 0.0001). In patients with symptomatic rhinitis, RHINASTHMA were lower in controlled asthma patients (UA P = 0.002; LA P < 0.0001; RAI P < 0.01; GS P < 0.0001). Asthma control was associated with lower T5SS score (P = 0.034). Conclusion:, Asthma control in real life is unsatisfactory. Rhinitis and asthma influence each other in terms of control and HRQoL. The control of rhinitis in asthma patients can lead to an optimization of HRQoL related to the upper airways, while this phenomenon is not so evident in asthma. These results suggest to strengthen the ARIA recommendation that asthma patients must be evaluated for rhinitis and vice versa. [source]

    Mechanisms determining cholinergic neural responses in airways of young and mature rabbits,

    Gary L. Larsen MD
    Abstract Neural pathways help control airway caliber and responsiveness. Yet little is known of how neural control changes as a function of development. In rabbits, we found electrical field stimulation (EFS) of airway nerves led to more marked contractile responses in 2- vs. 13-week-old animals. This enhanced response to EFS may be due to prejunctional, junctional, and/or postjunctional neural mechanisms. We assessed these mechanisms in airways of 2- and 13-week-old rabbits. The contractile responses to methacholine did not differ in the groups, suggesting postjunctional neural events are not primarily responsible for differing responses to EFS. To address junctional events, acetylcholinesterase (AChE) was measured (spectrophotometry). AChE was elevated in 2-week-olds. However, this should lead to less and not greater responses. Prejunctionally, EFS-induced acetylcholine (ACh) release was assessed by HPLC. Airways of 2-week-old rabbits released significantly more ACh than airways from mature rabbits. Choline acetyltransferase, a marker of cholinergic nerves, was not different between groups, suggesting that more ACh release in young rabbits was not due to increased nerve density. ACh release in the presence of polyarginine increased significantly in both groups, supporting the presence of functional muscarinic autoreceptors (M2) at both ages. Because substance P (SP) increases release of ACh, SP was measured by ELISA. This neuropeptide was significantly elevated in airways of younger rabbits. Nerve growth factor (NGF) increased SP and was also significantly increased in airways from younger rabbits. This work suggests that increases in EFS-induced responsiveness in young rabbits are likely due to prejunctional events with enhanced release of ACh. Increases in NGF and SP early in life may contribute to this increased responsiveness. Pediatr Pulmonol. 2004; 38:97,106. © 2004 Wiley-Liss, Inc. [source]

    Hypoxia Depresses Nitric Oxide Output in the Human Nasal Airways

    THE LARYNGOSCOPE, Issue 3 2000
    James S. J. Haight MD
    Abstract Objectives The role of oxygen in the nasal air on nasal nitric oxide (NO) output was studied in 13 adult volunteers. Methods Nasal NO was measured while air containing oxygen (0%,100% in nitrogen) was aspirated through the nasal airway before and after the topical application of xylometazoline. Results The mean nasal NO output of the untreated nose was 507.8 ± 161.9 nL/min (mean ± SD) when 21% oxygen was aspirated through the nasal cavities in series and remained unaltered by 100% O2 (P = .79). Below 10% oxygen the reduction in nasal NO output correlated positively and significantly with the decrease in oxygen concentration (r2 = 0.14). NO output was 245.2 ± 153.4 nL/min at 0% oxygen, a significant decline from 21% oxygen (P < .0001). Nasal vasoconstriction induced by xylometazoline and alterations in the blood oxygen content by a maximal breath-holding or breathing 100% oxygen did not alter nasal NO in hypoxia (P = .41). Conclusions Nasal NO output is markedly depressed in hypoxia and is oxygen dependent at concentrations of less than 10%. Approximately 50% of nasally generated NO is produced from oxygen in nasal air or regulated by it. [source]

    Respiratory muscle performance with stretch-shortening cycle manoeuvres: maximal inspiratory pressure,flow curves

    ACTA PHYSIOLOGICA, Issue 3 2005
    G. E. Tzelepis
    Abstract Aim:, To test the hypothesis that the maximal inspiratory muscle (IM) performance, as assessed by the maximal IM pressure,flow relationship, is enhanced with the stretch-shortening cycle (SSC). Methods:, Maximal inspiratory flow,pressure curves were measured in 12 healthy volunteers (35 ± 6 years) during maximal single efforts through a range of graded resistors (4-, 6-, and 8-mm diameter orifices), against an occluded airway, and with a minimal load (wide-open resistor). Maximal inspiratory efforts were initiated at a volume near residual lung volume (RV). The subjects exhaled to RV using slow (S) or fast (F) manoeuvres. With the S manoeuvre, they exhaled slowly to RV and held the breath at RV for about 4 s prior to maximal inspiration. With the F manoeuvre, they exhaled rapidly to RV and immediately inhaled maximally without a post-expiratory hold; a strategy designed to enhance inspiratory pressure via the SSC. Results:, The maximal inspiratory pressure,flow relationship was linear with the S and F manoeuvres (r2 = 0.88 for S and r2 = 0.88 for F manoeuvre, P < 0.0005 in all subjects). With the F manoeuvre, the pressure,flow relationship shifted to the right in a parallel fashion and the calculated maximal power increased by approximately 10% (P < 0.05) over that calculated with the S manoeuvre. Conclusion:, The maximal inspiratory pressure,flow capacity can be enhanced with SSC manoeuvres in a manner analogous to increases in the force,velocity relationship with SSC reported for skeletal muscles. [source]

    Randomized comparison of the SLIPA (Streamlined Liner of the Pharynx Airway) and the SS-LM (Soft Seal Laryngeal Mask) by medical students

    Cindy Hein
    Abstract Objective:, The aim of the study was to compare the Streamlined Liner of the Pharynx Airway (SLIPA; Hudson RCI), a new supraglottic airway device, with the Soft Seal Laryngeal Mask (SS-LM; Portex) when used by novices. Methods:, Thirty-six medical students with no previous airway experience, received manikin training in the use of the SLIPA and the SS-LM. Once proficient, the students inserted each device in randomized sequence, in two separate patients in the operating theatre. Only two insertion attempts per patient were allowed. Students were assessed in terms of: device preference; success or failure; success at first attempt and time to ventilation. Results:, Sixty-seven per cent of the students preferred to use the SLIPA (95% confidence interval 49,81%). The SLIPA was successfully inserted (one or two attempts) in 94% of patients (34/36) and the SS-LM in 89% (32/36) (P = 0.39). First attempt success rates were 83% (30/36) and 67% (24/36) in the SLIPA and SS-LM, respectively (P = 0.10). Median time to ventilation was shorter with the SLIPA (40.6 s) than with the SS-LM (66.9 s) when it was the first device used (P = 0.004), but times were similar when inserting the second device (43.8 s vs 42.9 s) (P = 0.75). Conclusions:, In the present study novice users demonstrated high success rates with both devices. The SLIPA group achieved shorter times to ventilation when it was the first device they inserted, which might prove to be of clinical significance, particularly in resuscitation attempts. Although the Laryngeal Mask has gained wide recognition for use by both novice users and as a rescue airway in failed intubation, the data presented here suggest that the SLIPA might also prove useful in these areas. [source]

    Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristics

    Summary Reason for performing study: The necessary degree of arytenoid cartilage abduction (ACA) to restore airway patency at maximal exercise has not been determined. Objectives: Use computational fluid dynamics modelling to measure the effects of different degrees of ACA on upper airway characteristics of horses during exercise. Hypothesis: Maximal ACA by laryngoplasty is necessary to restore normal peak airflow and pressure in Thoroughbred racehorses with laryngeal hemiplegia. Methods: The upper airway was modeled with the left arytenoid in 3 different positions: maximal abduction; 88% cross-sectional area of the rima glottis; and 75% cross-sectional area of the rima glottis. The right arytenoid cartilage was maximally abducted. Two models were assumed: Model 1: no compensation of airway pressures; and Model 2: airway pressure compensation occurs to maintain peak airflow. The cross-sectional pressure and velocity distributions for turbulent flow were studied at peak flow and at different positions along the airway. Results: Model 1: In the absence of a change in driving pressure, 12 and 25% reductions in cross-sectional area of the larynx resulted in 4.11 and 5.65% reductions in peak airflow and 3.68 and 5.64% in tidal volume, respectively, with mild changes in wall pressure. Model 2: To maintain peak flow, a 6.27% increase in driving tracheal pressure was required to compensate for a cross-sectional reduction of 12% and a 13.63% increase in driving tracheal pressure was needed for a cross-sectional area reduction of 25%. This increase in negative driving pressure resulted in regions with low intraluminal and wall pressures, depending on the degree of airway diameter reduction. Conclusion: Assuming no increase in driving pressure, the decrease in left ACA reduced airflow and tidal volume. With increasing driving pressure, a decrease in left ACA changed the wall pressure profile, subjecting the submaximally abducted arytenoid cartilage and adjacent areas to airway collapse. Clinical relevance: The surgical target of ACA resulting in 88% of maximal cross-sectional area seems to be appropriate. [source]

    Development of equine upper airway fluid mechanics model for Thoroughbred racehorses

    Summary Reason for performing study: Computational fluid dynamics (CFD) models provide the means to evaluate airflow in the upper airways without requiring in vivo experiments. Hypothesis: The physiological conditions of a Thoroughbred racehorse's upper airway during exercise could be simulated. Methods: Computed tomography scanned images of a 3-year-old intact male Thoroughbred racehorse cadaver were used to simulate in vivo geometry. Airway pressure traces from a live Thoroughbred horse, during exercise was used to set the boundary condition. Fluid-flow equations were solved for turbulent flow in the airway during inspiratory and expiratory phases. The wall pressure turbulent kinetic energy and velocity distributions were studied at different cross-sections along the airway. This provided insight into the general flow pattern and helped identify regions susceptible to dynamic collapse. Results: The airflow velocity and static tracheal pressure were comparable to data of horses exercising on a high-speed treadmill reported in recent literature. The cross-sectional area of the fully dilated rima glottidis was 7% greater than the trachea. During inspiration, the area of highest turbulence (i.e. kinetic energy) was in the larynx, the rostral aspect of the nasopharynx was subjected to the most negative wall pressure and the highest airflow velocity is more caudal on the ventral aspect of the nasopharynx (i.e. the soft palate). During exhalation, the area of highest turbulence was in the rostral and mid-nasopharynx, the maximum positive pressure was observed at the caudal aspect of the soft palate and the highest airflow velocity at the front of the nasopharynx. Conclusions and clinical relevance: In the equine upper airway collapsible area, the floor of the rostral aspect of the nasopharynx is subjected to the most significant collapsing pressure with high average turbulent kinetic during inhalation, which may lead to palatal instability and explain the high prevalence of dorsal displacement of the soft palate (DDSP) in racehorses. Maximal abduction of the arytenoid cartilage may not be needed for optimal performance, since the trachea cross-sectional area is 7% smaller than the rima glottidis. [source]

    Videoendoscopic evaluation of the upper respiratory tract in 93 sport horses during exercise testing on a high-speed treadmill

    Summary Reasons for performing study: Videoendoscopy of the upper respiratory tract (URT) during high-speed treadmill exercise has proved to be invaluable in the assessment of URT dysfunction in racehorses. However, very little information exists regarding dynamic airway collapse in other sport horses used in nonracing equestrian disciplines. Objectives: To evaluate the videoendoscopic findings at rest and during exercise in a mixed population of sport horses referred for investigation of poor athletic performance and/or abnormal respiratory noise. Methods: Videoendoscopy of the upper airway was performed at rest and during high-speed treadmill exercise in 93 horses. Results: Dynamic airway obstructions were diagnosed in 77% of horses and were frequently complex in nature. The most common forms of dynamic collapse included soft palate dysfunction (54%), dynamic laryngeal collapse (38%), axial deviation of the aryepiglottic folds (24%) and pharyngeal wall collapse (18%). In the majority of horses, no obvious abnormalities were identified at rest. Enforced poll flexion was found to be a contributing factor in 24% of cases. Conclusions: Dynamic obstructions of the URT were a common cause of poor performance and/or abnormal respiratory noise in sport horses referred for investigation of performance problems. Potential relevance: This study highlights the importance of videoendoscopic evaluation of the URT during exercise in horses utilised for equestrian sports where exercise during competition is submaximal in nature. [source]

    Airway inflammation in Michigan pleasure horses: prevalence and risk factors

    N. E. Robinson
    Summary Reasons for performing study: Although subclinical airway inflammation is thought to be common in horses, there is little information on its prevalence and none on risk factors. Objective: To determine the prevalence and risk factors for an increased number of inflammatory cells and for mucus accumulation in the trachea of pleasure horses. Methods: Horses (n = 266) in stables (n = 21) in Michigan were examined endoscopically, once in winter and once in summer 2004. Visible tracheal mucoid secretions were graded 0,5 and inflammatory cell numbers counted in a tracheal lavage sample. Information collected about each horse included age, gender, presence of cough, percent time indoors and source of roughage. The repeated measures were analysed by generalised estimating equations and linear mixed models. Results: Horses eating hay, especially from round bales, had the most neutrophils, whereas horses feeding from pasture had the fewest. Being female and being outdoors in winter were associated with increased numbers of inflammatory cells. Older horses had fewer macrophages than young horses. More than 70% of horses had >20% neutrophils in tracheal lavage. Twenty percent of horses had a mucus accumulation score >1; 17% had both a mucus score >1 and >20% neutrophils. The significant risk factors for mucus accumulation >1 were age >15 years, feeding on hay as compared to pasture, and being outdoors for more than 80% time in winter. Even though mucus accumulation score >1 was a risk factor for cough, only half of such horses coughed. Cough and mucus accumulation were associated with increased number of neutrophils. Conclusions: In comparison to pasture feeding, hay feeding, particularly from round bales, was associated with an increased number of neutrophils in the airway. Being outdoors in winter was associated with increased numbers of inflammatory cells and with mucus accumulation. Because 70% of horses have >20% neutrophils, this value should not be used as the sole indicator of airway inflammation. Potential relevance: The study reinforces the importance of hay feeding and older age as risk factors for inflammatory airway disease. Horses that do not have ,heaves' may be best kept indoors when winters are cold. [source]

    Mast cells play a key role in the developmentof late airway hyperresponsiveness through TNF-,in a murine model of asthma

    Young-Suk Kim
    Abstract We have investigated the role of TNF-, in mast cell-mediated late airway hyperresponsiveness (AHR) using mast cell-deficient WBB6F1- W/Wv (W/Wv) mice in a murine model of asthma, which exhibits a biphasic increase in AHR. TNF-, levels in the airway and magnitude of late AHR in response to airway allergen challenge were severely impaired in W/Wv mice compared to their littermates. In addition to TNF-,, cytosolic phospholipase A2 (cPLA2) phosphorylation and enzymatic activity in the lungs were also impaired in W/Wv mice. Either anti-TNF-, antibody or an inhibitor of cPLA2 abolished late AHR in congeneic +/+ mice. Intratracheal administration of TNF-, resulted in increases in late AHR, cPLA2 phosphorylation, cPLA2 activity, and phosphorylation of mitogen-activated protein kinases. Mast cell replacement restored airway TNF-, level, cPLA2 phosphorylation and enzymatic activity in the lungs as well as late AHR in W/Wv mice. These data indicate that mast cells play a key role in the development of late AHR through liberation of TNF-,. [source]