Airways Of Dogs Research Articles

Staphylectomy in pug bitches using ultrasonic scalpel and rhinoplasty

Brachycephalic Syndrome is a combination of anatomical and physiological abnormalities that results in the obstruction of the airways in short-snouted dogs. These animals have primary malformations such as stenotic nares and an elongated soft palate, which can lead to secondary malformations over time. Each animal can present these abnormalities with different degrees of intensity. The patient may present clinical signs such as snoring while awake and asleep, cough, choking, exercise intolerance, dysphagia, reverse sneezing, dyspnea, and cyaniasis. These abnormalities from brachycephalic syndrome are progressive and degenerative. The report aims to present the surgical techniques of a staphylectomy using an ultrasonic scalpel and rhinoplasty, used to correct respiratory syndrome in a pug canine, combined with the diagnosis and treatment of secondary respiratory alterations through laryngotracheobronchoscopy.

Tongue worm (Linguatula serrata) infection in a dog imported into the United Kingdom from Romania

AbstractLinguatula serrata, also known as tongue worm, is a zoonotic parasite that lives in the nasal airways of dogs where it is responsible for mild to severe rhinosinusitis. In recent years, the number of pets entering the United Kingdom from abroad has increased, with a coinciding increase in the number of L. serrata infections diagnosed in UK veterinary clinics. Here, we report a case of linguatulosis in a 10‐month‐old rescued dog imported from Romania. Two weeks post‐arrival, the dog showed coughing, nasal discharge, epiphora and respiratory distress. Two worm‐like parasites were expelled by sneezing and they were morphologically identified as L. serrata. L. serrata eggs were also detected. A macrocyclic lactone treatment was administered, and clinical signs resolved. L. serrata should be included in the differential diagnosis of respiratory disease in imported dogs. Due to the zoonotic potential of this parasite, rapid diagnosis and correct treatment is essential.

Risk Factors and Outcomes in Dogs With Respiratory Disease Undergoing Diagnostic Airway Lavage.

Advanced diagnostic testing is becoming increasingly important to accurately assess pulmonary parenchymal, airway, and pulmonary vascular diseases in dogs. Due to respiratory system compromise, diagnostic procedures performed under general anesthesia, including thoracic computed tomography (CT) and bronchoalveolar lavage (BAL), are thought to carry significant risk to dogs with respiratory disease. In lieu of performing these diagnostics, empirical medical therapy is often administered, potentially delaying appropriate therapy or providing unnecessary treatment. This study prospectively evaluated risk factors and outcomes for dogs with respiratory disease undergoing general anesthesia for thoracic CT and BAL. Arterial blood gas samples were taken pre- and post-BAL to evaluate pulmonary gas exchange. Pre-BAL arterial partial pressure of oxygen-to-fractional inspired oxygen ratio was used to stratify dogs into groups of mild or moderate to severe disease severity. A novel thoracic CT disease severity scoring system was used to independently stratify dogs into mild or moderate to severe groups. Statistical comparisons between groups were made for signalment, body weight, temperature, pulse, respiratory rate, WBC count, ventilator-acquired pulmonary mechanics (specific compliance and resistance), change in arterial partial pressure of oxygen post-BAL, and outcomes. Seventeen dogs were prospectively enrolled. A comparatively lower heart rate at presentation was the only potential marker of increased disease severity identified when stratified by CT severity score. Arterial partial pressure of oxygen did not significantly decrease post-BAL regardless of disease severity or stratification method. The CT scoring system significantly correlated with the pre-BAL arterial partial pressure of oxygen-to-fractional inspired oxygen ratio. Incidence of post-procedural complications was 18%, with all complications being transient. Mortality as a direct complication of diagnostics was 0%. When considering euthanasia secondary to severity of the underlying disease and poor prognosis or death due to unrelated disease, mortality was 18%. In dogs with respiratory disease undergoing advanced diagnostic procedures, the overall incidence of post-procedural morbidity was low with no mortality directly attributed to the procedures. A novel CT disease severity scoring system was utilized and shows promise as a tool for evaluation of disease severity in this patient population when compared to arterial blood gas analysis.

Detection of selected viral pathogens in dogs with canine infectious respiratory disease in Austria

ObjectivesTo assess the prevalence of canine parainfluenza virus, canine adenovirus type 2, canine distemper virus, canine respiratory coronavirus and influenza virus A infections in: (1) privately‐owned or, (2) kennelled dogs showing signs consistent with canine infectious respiratory disease and, (3) clinically healthy dogs in Vienna, Austria.Materials and MethodsProspectively, nasal and tonsillar swabs from 214 dogs affected with infectious respiratory disease, and 50 healthy control dogs were tested for nucleic acids specific to the various viral infections. Concurrent bronchoalveolar lavage fluid from 31 dogs with chronic respiratory disease was investigated for the same viral pathogens. Additionally, anti‐canine respiratory coronavirus antibody concentrations were measured in paired blood samples from 30 acutely diseased dogs.ResultsCanine respiratory coronavirus (7.5%) and canine parainfluenza virus (6.5%) were the most commonly detected viruses in samples from the upper airways of dogs with respiratory infections. Serological results showed a significant seroconversion in response to coronavirus in 50% of the examined cases. None of the samples was positive for influenza virus A‐specific nucleic acid. Canine coronavirus‐specific nucleic acid was detected in 4.0% of healthy dogs.Clinical SignificanceCanine coronavirus should be considered as a clinically relevant cause of infectious respiratory disease in crowded dog populations. For sample collection, the nasal mucosa can be recommended as the favoured site. Analysis of paired serum samples aids verification of canine coronavirus infection in respiratory disease.

CT-based anatomical features of large airway and heart volume in dogs of different body size

Differences in the prevalence and clinical signs of cardiopulmonary diseases in dogs of different body sizes have been reported. It was hypothesized that the anatomical features of the heart and large airways varies by body size in dogs and might influence clinical manifestations of cardiopulmonary disease. The purpose of this study was to compare various anatomical features of the thoracic organs (heart, trachea, etc.) in dogs according to body size using computed tomography (CT) images.Dogs without clinically significant heart and lung disease (n=226) that underwent CT were divided into three groups on the basis of bodyweight: small (<7kg), medium (7–20kg), and large (>20kg). The following parameters were calculated from CT images using OsiriX and compared among groups: relative heart volume (heart volume/thoracic volume), relative distance from mainstem bronchi to vertebra (distance from mainstem bronchi to vertebra/heart length), longitudinal/transverse diameter ratio of trachea, and angle of bronchus. Small dogs had larger hearts relative to their thorax, a shorter distance from the heart to the vertebra, and laterally-elongated oval-shaped tracheas, compared to medium and/or large dogs. These differences in anatomical features according to body size may potentially contribute to different clinical manifestations when the heart is enlarged.

ПАТОЛОГОАНАТОМІЧНА ХАРАКТЕРИСТИКА ВИПАДКІВ АНОМАЛІЇ РОЗВИТКУ ТРАХЕЇ ТА БРОНХІВ У СОБАК

One of the chronic disease of upper airways in dogs is a «tracheal collapse» or a «dorsoventral flattening of trachea». This disease does not have a finally defined cause and pathogenesis. There are some facts about the possibility of the disease development as a congenital pathology for a great number of dog breeds. Furthermore, the secondary development of this disease can also happen because of the environmental conditions. Nowadays, it is considered that the most important components of pathogenesis of tracheal collapse are congential or acquired defects of tracheal connective and cartilaginous tissue. Relying upon proven existence of airways wall pathologies because of dysplasia of connective tissue in people, authors suppose that the «tracheal collapse», or the «dorsoventral flattening of trachea» is not independent disease of dogs but it is just one of the symptoms of systemic connective tissue dysplasia. The purpose of the study was the identification of systemic or specific organ pathologies in dogs which accompany the tracheal collapse. The research was performed by the pathologoanatomical analysis of the results of corpse dissection of different dogs breeds which had taken place at the pathological anatomy and dissection department of Kharkov State Veterinary Academy for the last 8 years. Finally, 11 results of the dog bodies dissections were analyzed. According to the results of performed analysis, tracheal collapse or dorsoventral flattening of trachea are registered in different dog breeds, including metises. Most dogs have asymptomatic disease course. It was also established that dog dorsoventral flattening of trachea comes together with other pathologies which include systemic pathologies of connective tissue in different organs. From 11 examined cases, 45% of dogs had tracheal collapse combined with spondiloarthral pathologies. These pathologies are represented by deformations of big joints of limbs, spinal column and intervertebral cartilages pathologies which manifest in lordosis. In 18% of corpses, tracheal collapse was combined with pathologies of colon wall (megacolon) and periodontal pathologies. In 27% of cases, pathomorphological characteristics of tracheobronchial collapse were accompanied with mitral insufficiency and pathologies of endocardial fibrous base. According to the results of the dissections the studied pathology of tracheal and bronchial walls in dogs is one of the symptom of the systemic disturbance of connective tissue development. Authors suppose to term this pathology as tracheobronchial dysplasia instead of dorsoventral flattening of trachea or tracheal collapse. The primary tracheobronchial dysplasia in dogs can't be considered as an independent disease so sick animals should be studied in order to find out other systemic or specific organ pathologies. Prognosis and possibility of treatment should to be determined according to these pathologies. Further research can be aimed to investigate special characteristics of connective tissue organization.

High prevalence of Eucoleus boehmi (syn. Capillaria boehmi) in foxes from western Austria.

Eucoleus boehmi (syn. Capillaria boehmi) is a canine trichuroid nematode affecting the upper respiratory airways (i.e., nasal cavity and paranasal sinuses) of dogs, foxes, and wolves. In the past few years, reports in dogs and wild canids have increased from across Europe, but data on its occurrence and distribution in Austria is scanty. A total of 47 red foxes (Vulpes vulpes) from the two westernmost provinces (Tyrol and Vorarlberg) of Austria were therefore examined for the presence of E. boehmi at necropsy. Eggs and adult nematodes were identified morphologically and molecularly (cox1) as E. boehmi. These nematodes were found in 26 (78.8 %) and 13 (92.9 %) foxes from Tyrol and Vorarlberg, respectively, with an overall prevalence of 83.0 % (39/47). The prevalence rate of infection recorded in this study is among the highest in Europe. These results suggest that foxes may represent an important source of infection for dogs and other canids, but further studies are needed to elucidate the transmission dynamics.

A Novel Approach to Brachycephalic Syndrome. 2. Laser-Assisted Turbinectomy (LATE).

To introduce a new surgical procedure based on interventional, laser-assisted removal of obstructing turbinate tissue to improve endonasal airway patency in brachycephalic dogs and to confirm the short and long term results using computed tomography (CT) and rhinoscopy. Prospective clinical study. Brachycephalic dogs (n = 158; 70 Pugs, 77 French Bulldogs, 11 English Bulldogs) referred for treatment of severe respiratory distress because of brachycephalic syndrome. Computed tomography and anterior and posterior rhinoscopy were performed to evaluate endonasal obstruction. Laser-assisted turbinectomy (LATE) using a diode laser was performed as part of a multilevel surgery. Nasal conchae that were causing airway obstruction were removed. The obstructing parts of the conchae were safely and efficiently removed by LATE, shaping a patent nasal airway in all dogs. The newly developed surgical procedure involved 3 steps: turbinectomy of the (1) concha nasalis ventralis; (2) rostral aberrantly growing turbinates (RAT); and (3) caudal aberrantly growing turbinates (CAT). Complications of the procedure included transient intraoperative hemorrhage in 51 of 158 dogs (32.3%); however, a temporary tamponade was necessary in only 2/158 dogs (1.3%). After 6 months, regrowth of turbinates required resection of possibly re-obstructing tissue in 25/158 dogs (15.8%; 1 Pug and 24 French Bulldogs). LATE is an effective method for creating a patent nasal airway in brachycephalic dogs with intranasal obstruction.

Tobacco exposure increased airway limitation in dogs with chronic cough

In the field of veterinary medicine, there are few reports regarding the incidence of respiratory diseases, including cancer of the nose and lung among pet animals with passive tobacco smoke...

Endobronchial Injection of Botulinum Toxin for the Reduction of Bronchial Hyperreactivity Induced by Methacholine Inhalation in Dogs

Airway smooth muscle contraction causes bronchial constriction and is the main cause of bronchospasm in response to stimulants in asthma patients. In this pilot study, we tested the possibility of using a commercially available neurotoxin-botulinum toxin A (BTX-A)-to reduce bronchial hyperreactivity in dogs. Two bronchoscopic sessions were conducted in 6 healthy mongrel dogs. In the first session, BTX-A (concentration 10 U/mL) was injected in small aliquots submucosally in 1 caudal lobe and its subsegments, leaving the other side as control. During the second bronchoscopy conducted 2 weeks later, the airway calibers of the treated and untreated sides were measured in each animal before and after instillation of methacholine in the airways to induce bronchial hyperreactivity (concentration 25 mg/mL). The mean pretreatment diameter was 3.356 (± 1.294) mm and 2.765 (± 0.603) mm in the treated and untreated airways, respectively. After provocation with methacholine, the diameter of the treated airways was 1.985 (± 0.888) mm versus 0.873 (± 0.833) mm in the untreated airways (P=0.000). Local injection of BTX-A in the airway resulted in reduction of bronchial hyperreactivity by 58.6% (P=0.001). There were no complications resulting from the submucosal injection of BTX-A in the airways. Endobronchial injection of BTX-A reduces bronchial hyperreactivity in the airways of healthy dogs.

Ventilation heterogeneity: small length scales, big challenges

the distribution of regional ventilation is heterogeneous in normal lung and increases dramatically under pathological conditions. This has been demonstrated both in humans and in animal models using a number of different imaging techniques. General anesthesia and mechanical ventilation can

The neurophysiology of dyspnea

AbstractObjective – To review the human and veterinary literature regarding the neurophysiology of dyspnea and to provide evidence for the beneficial effects of several novel therapies aimed at the alleviation of dyspneic sensations.Data Sources – Data sources included scientific reviews, case reports, original research publications, and recent research conference proceedings.Human Data Synthesis – The use of blood oxygenation level‐dependent functional magnetic resonance imaging technology has revealed that the brain regions activated by air hunger in humans are also those activated by fear, pain, and thirst perception. In human subjects, it has been found that agents known to enhance the firing of pulmonary slowly adapting receptors (SARs) can alleviate the sensation of dyspnea without altering central respiratory drive. Several small studies have also shown that nebulized opioids can reduce the sensation of dyspnea apparently via activation of peripheral opioid receptors in the lung.Veterinary Data Synthesis – There are several animal models relevant to both small and large animal clinical patient populations. Treatment of rats with a nebulized SAR sensitizing agent (furosemide) enhances SAR firing in response to lung inflation. Behavioral escape responses to airway occlusion are reduced in lightly anesthetized cats when treated with nebulized furosemide. Opioid agonists have been shown to inhibit the release of acetylcholine and other mediators from the airways of dogs and guinea pigs. Studies using a goat model with bilateral destruction of the pre‐Bötzinger Complex do not support current paradigms of air hunger origination.Conclusions – Veterinary patients may benefit from an approach to dyspnea that incorporates an understanding of the origins of the unpleasant sensations associated with the condition. Several novel therapies have shown promise in alleviating dyspneic sensations without altering respiratory drive. Further study is needed to determine the safety and efficacy of these therapies in veterinary patients.

Guidelines and criteria for the placement of laryngeal mask airways in dogs

ObjectiveTo evaluate the criteria for the insertion and correct placement of the laryngeal mask airway (LMA) in dogs. Study designProspective descriptive clinical study. AnimalsThirty healthy dogs (ASA I or II) of different breeds, age 0.33–7.0 years (2.8 ± 2.1; mean ± SD), weight 2.2–59.0 kg (23.9 ± 14.4), anaesthetized for elective surgery.Materials and methods The dogs were sedated with intravenous (IV) medetomidine (10 μg kg−1) and butorphanol (0.2 mg kg−1). If considered necessary, IV propofol (1 mg kg−1 over 30 seconds) was administered until the LMA was inserted and positioned correctly. The position of the LMA was evaluated using predefined criteria for its insertion and inflation of the cuff, together with the ability to ventilate the dogs through the LMA. ResultsThe criteria for insertion, inflation and ventilation which indicated a clinically optimal position of the LMA and its seal around the larynx were met in 19 dogs (63.3%). The dogs could be manually ventilated with inspiratory peak pressures of 10 cm H2O without capnographic or audible evidence of leakage. In 11 dogs (36.7%), the LMA was positioned suboptimally with leakage during manual ventilation with inspiratory peak pressures not exceeding 10 cmH2O. There was no evidence of breed-related differences in LMA placement and position. Conclusions and clinical relevanceThe technique for the insertion of the LMA using predefined criteria to evaluate a correct positioning and a seal led to a successful placement in dogs of both brachycephalic and nonbrachycephalic breeds. The LMA, in most of the dogs, was easily placed, well tolerated and offered a useful less invasive means of securing the upper airway.

Commentary on “The role of the large airways on smooth muscle contraction in asthma”

LETTERS TO THE EDITORCommentary on “The role of the large airways on smooth muscle contraction in asthma”Peter MacklemPeter MacklemPublished Online:01 Oct 2007https://doi.org/10.1152/japplphysiol.00646.2007MoreSectionsPDF (22 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat to the editor: Permutt (4) in his viewpoint article states that in asthmatics at TLC after albuterol, when airways are as dilated as they can get, “the smaller the… diameters of the… large airways, the smaller was the FEV1/FVC% predicted” and that dynamic hyperinflation resulted from “increased expiratory resistance arising from the narrowed lumen of… large airways…” This is because these airways are the major site of resistance in the normal tracheobronchial tree (2, 3) and presumably also in maximally bronchodilated asthmatics. If they bronchoconstrict, the effect on pulmonary resistance and maximal expiratory flows is considerably greater than for the same degree of narrowing of peripheral airways (1, 6).A substantial part of Permutt's viewpoint deals with absolute lung volumes, which were probably overestimated due to failure of mouth and alveolar pressures to equilibrate during the plethysmographic panting maneuver (5). Because airway resistance is a major determinant of the time required for equilibration, the narrowing of large high-resistance airways are probably responsible for this artifact. If so, the magnitude of the artifact should correlate with large airway diameter. It is easy to show that as the magnitude of this error increases, the FRC ratio (which plays a prominent role in Permutt's analysis) systematically decreases. So the artifact, in a sense strengthens Permutt's case because everything, dynamic hyperinflation, bronchial hyperresponsiveness, asthma severity, even maybe gas trapping and the artifact can be traced to the narrowing of the most resistive airways in the tracheobronchial tree. This is not very surprising.REFERENCES1 Gardiner AJ, Wood L, Gayrard P, Menkes H, Macklem P. Influence of constriction in central or peripheral airways on maximal expiratory flow rates in dogs. J Appl Physiol 36: 554–560, 1974.Link | ISI | Google Scholar2 Macklem PT, Mead J. Resistance of central and peripheral airways measured by a retrograde catheter. J Appl Physiol 22: 395–401, 1967.Link | ISI | Google Scholar3 Macklem PT, Woolcock AJ, Hogg JC, Nadel JA, Wilson NJ. Partitioning of pulmonary resistance in the dog. J Appl Physiol 26: 798–805, 1969.Link | ISI | Google Scholar4 Permutt S. The role of the large airways on smooth muscle contraction in asthma. J Appl Physiol; doi:10.1152/japplphysiol.00568.2007.Google Scholar5 Stanescu DC. The structural basis of airways hyperresponsiveness in asthma. J Appl Physiol 101: 1812, 2006.Link | ISI | Google Scholar6 Woolcock AJ, Macklem PT, Hogg JC, Wilson NJ, Nadel JA, Frank NR, Brain J. Effect of vagal stimulation on central and peripheral airways in dogs. J Appl Physiol 26: 806–813, 1969.Link | ISI | Google ScholarAUTHOR NOTESAddress for correspondence: P. Macklem, P. O. Box 250, Lansdowne, Ontario, Canada K0E 120 (e-mail: [email protected]) Download PDF Previous Back to Top Next FiguresReferencesRelatedInformationCited ByLast Word on Viewpoint “The role of the large airways on smooth muscle contraction in asthma”Solbert Permutt1 October 2007 | Journal of Applied Physiology, Vol. 103, No. 4 More from this issue > Volume 103Issue 4October 2007Pages 1459-1459 Copyright & PermissionsCopyright © 2007 the American Physiological Societyhttps://doi.org/10.1152/japplphysiol.00646.2007PubMed17916683History Published online 1 October 2007 Published in print 1 October 2007 Metrics

Local T-cell activation after segmental allergen challenge in the lungs of allergic dogs.

Dogs with immunoglobulin E (IgE) allergy for ragweed that are sensitized by intrapulmonary exposure to ragweed can be used to study the pulmonary immune response that is important in allergic asthma. Using this model, we tested the hypothesis that T lymphocytes are activated locally in the airways shortly after allergen exposure of the lungs. The airways of six allergic dogs and three non-allergic dogs were exposed to ragweed by segmental allergen challenge (SAC). T-cell subsets and T-cell activation in blood and bronchoalveolar lavage (BAL) fluid were measured by flow cytometry before SAC and at 4, 24 and 72 hr thereafter. SAC caused a statistically significant increase in the percentage of major histocompatibility complex (MHC) class II-positive CD4 and CD8 T cells in BAL fluid and a significant increase in the mean fluorescent activity of MHC class II from 4 hr after SAC onward. This activation was significantly different from that found in cells from lung lobes challenged with saline, or from lung lobes in non-allergic dogs challenged with ragweed. The percentage of CD45RA(bright) CD8 cells increased significantly in allergic dogs after both ragweed and saline challenges. This was significantly higher than in non-allergic dogs. We conclude that T-cell activation in the airways of dogs can be measured after in vivo activation of the cells by measuring MHC class II and CD45RA expression in BAL fluid T cells. Furthermore, in allergic dogs, T cells are activated locally in the lungs within 4 hr after exposure to ragweed allergen. These results suggest a role for T lymphocytes in the development of late-phase allergic reactions in the airways.

An immunologic investigation of canine eosinophilic bronchopneumopathy.

Immunologic variables in dogs with eosinophilic bronchopneumopathy (EBP) have not been extensively evaluated. The aim of this study was to determine immunoglobulin (Ig) concentrations and to perform phenotypic subtyping of lymphocytes in the bronchoalveolar lavage fluid (BALF) and peripheral blood (PB) of 12 dogs with EBP at the time of diagnosis (TD) and to compare these data with those obtained in healthy dogs, as well as in EBP dogs after antibiotic therapy (TAB) and during corticosteroid treatment (TM). Matched samples of serum and BALF were used to determine Ig concentrations (IgG, IgM, and IgA) by capture enzyme-linked immunosorbent assay (ELISA), from which a secretory index (SI) was calculated. Lymphocyte subpopulations were studied in the BALF and PB by flow cytometry. Log values of BALF IgM and IgA were significantly higher (0.64+/-0.05 and 1.06+/-0.13, respectively) in EBP dogs at TD than in controls and then tended to decrease at TM (0.55+/-0.03 and 1.02+/-0.17, respectively). A calculated SI for IgA was not significantly increased. In the BALF of dogs with EBg the CD4: CD8 was significantly (P < .05) higher (22.6+/-30.3) than in controls (3.2+/-1.9), due to significantly higher CD4+ T cells and lower CD8+ T cells. At TM, the BALF T-cell percentages returned to normal (2.4+/-0.6). We propose that the influx of eosinophils into the airway of dogs with EBP is at least in part mediated by cytokines derived from CD4+ T cells. Further studies of canine cytokines and chemokines will help determine whether canine EBP involves type I hypersensitivity mechanisms regulated by Th2 lymphocytes.

Bronchoconstrictive and relaxant effects of lidocaine on the airway in dogs.

Intravenous lidocaine commonly is used to treat ventricular arrhythmias and to attenuate reflex airway constriction and intracranial pressure elevation during airway manipulation in intensive care units. There is much controversy as to the actions of lidocaine on the airway, so the aim of this study was to compare, in detail, the actions of lidocaine with those of bupivacaine and procaine on airway caliber and the associated changes in plasma catecholamine concentrations in the dog. Prospective, randomized, controlled experimental in vivo and in vitro study. A university research laboratory. Mongrel dogs. In the first experiment, we evaluated the effects of intravenous local anesthetics--lidocaine 0-10 mg/kg (n = 7), bupivacaine 0-2.5 mg/kg (n = 7), or procaine 0-20 mg/kg (n = 7)--on basal airway tone. In second experiment, histamine (10 microg/kg + 500 microg x kg(-1) x hr(-1), n = 6), serotonin (10 microg/kg + 500 microg x kg(-1) x hr(-1), n = 7), and methacholine (0.5 microg/kg + 300 microg x kg(-1) x hr(-1), n = 7) were infused to determine the effects of lidocaine (0-10 mg/kg) on agonist-induced bronchoconstriction. In addition, the actions of lidocaine on vagal nerve stimulation were examined (n = 7). Bronchial cross-sectional area at the third bronchial bifurcation of dogs was monitored continuously through a fiberoptic bronchoscope. In the first experiment, all local anesthetics produced a dose-dependent decrease in basal bronchial cross-sectional area. In the second experiment, lidocaine significantly potentiated histamine and serotonin-induced bronchoconstriction. In contrast, lidocaine antagonized methacholine- and vagal nerve stimulation-induced bronchoconstriction. We have clearly demonstrated that lidocaine may produce direct bronchoconstriction and worsen some agonist-induced bronchoconstriction, but it prevents reflex airway constriction. Therefore, we suggest that this agent be used with caution in asthmatics.

Respiratory reflexes in response to upper-airway administration of sevoflurane and isoflurane in anesthetized, spontaneously breathing dogs.

To evaluate the respiratory effects occurring during administration of sevoflurane or isoflurane to the upper airway in dogs. A prospective, randomized study. Twelve healthy adult beagles (6 males, 6 females). At least 2 weeks after undergoing permanent tracheostomy, dogs were premedicated with acepromazine-buprenorphine, and anesthesia was induced with thiopental and maintained with alpha-chloralose. The upper airway was functionally isolated so that the inhalant could be administered to the upper airway while dogs were breathing 100% O2 via the tracheostomy. Respiratory reflexes in response to the administration of sevoflurane or isoflurane at concentrations of 1.2, 1.8, and 2.4 times the minimal alveolar concentration (MAC) (administered in 100% O2 at a flow rate of 5 L/min) were recorded. Reflexes in response to administration of each anesthetic were also recorded following upper-airway administration of lidocaine. Respiratory reflexes elicited by upper-airway administration of each anesthetic were characterized by a dose-dependent increase in expiration time, with a resultant decrease in respiratory minute ventilation and increase in end-tidal PCO2. The magnitude of these responses was greater with isoflurane than with sevoflurane at 1.8 and 2.4 MAC. These reflexes were abolished after lidocaine nebulization into the upper airway. Isoflurane induces greater reflex inhibition of breathing than does sevoflurane when the anesthetic is inhaled into the upper airway at concentrations used for mask induction.

Aspiration in chest compression alone without mechanical ventilation in the head down position in dogs

Background: Previous work by the authors has shown that chest compressions alone without mechanical ventilation during cardiopulmonary resuscitation in the natural supine position was associated with pulmonary aspiration in dogs. The purpose of this investigation was to test the hypothesis that a head down position may prevent aspiration during chest compressions alone and whether oxygenation can be improved by simply insufflation of oral oxygen 10 min after cardiac arrest. Methods: Cardiac arrest was induced in ten mongrel dogs which were anesthetized and paralysed. Eight underwent chest compressions alone in different head down positions using an automatic compressor at 9 kg compression force and 3 cm compression depth. The study was composed of two parts. Part 1 evaluated the effect of insufflation of 10 l/min O 2, into the mouth of the dogs, 10 min after initiation of resuscitation, using chest compressions alone. Part 2 was designed to test our hypothesis that the head down position may protect the lungs from aspiration during chest compression alone. The mouths of the dogs were filled with mixed barium and the dogs underwent serial episodes of chest compressions, for 10 min each, in the 20°head down, 10° head down and the natural supine positions. Chest X-rays with antero-posterior and lateral views were taken to evaluate pulmonary aspiration. Two additional dogs underwent direct chest compression alone in the natural supine position and the time of chest compression was shortened to 5 min. Results: All dogs in the natural position showed evidence of pulmonary aspiration of barium, five or six of the dogs showed tracheal aspiration in the 10° head down position, while no any barium was visualized in the tracheo-broncheal trees of the dogs in the 20° head down position. Supplemental oxygen in the mouth improved the mean Pa O 2 from 67±26 to 160±97 mmHg during chest compressions alone. Conclusion: Chest compression alone without mechanical ventilation in the supine position caused pulmonary aspiration in the unprotected airway in dogs. This complication could be prevented by adopting a 20° head down position. The10° head down position seemed to reduce the severity of the pulmonary aspiration, but not enough to eliminate the danger altogether. Supplemental oxygen in the mouth can improve oxygenation in chest compressions alone.

Allergen-induced IL-9 directly stimulates mucin transcription in respiratory epithelial cells.

A hallmark of asthma is mucin overproduction, a condition that contributes to airway obstruction. The events responsible for mucin overproduction are not known but are thought to be associated with mediators of chronic inflammation. Others have shown that T-helper 2 (Th2) lymphocytes are required for mucous cell metaplasia, which then leads to mucin overproduction in animal models of allergy. We hypothesized that Th2 cell mediators are present in asthmatic airway fluid and directly stimulate mucin synthesis in airway epithelial cells. Results in cultured airway epithelial cells showed that samples of asthmatic fluid stimulated mucin (MUC5AC) synthesis severalfold more potently than non-asthmatic fluid. Consistent with this, lavage fluid from the airways of allergen-challenged dogs stimulated mucin synthesis severalfold more potently than that from non-allergen-challenged dogs. Fractionation of dog samples revealed 2 active fractions at <10 kDa and 30-100 kDa. Th2 cytokines in these molecular weight ranges are IL-9 (36 kDa), IL-5 (56 kDa), and IL-13 (10 kDa). Antibody blockade of ligand-receptor interaction for IL-9 (but not IL-5 or IL-13) inhibited mucin stimulation by dog airway fluid. Furthermore, recombinant IL-9, but not IL-5 or IL-13, stimulated mucin synthesis. These results indicate that IL-9 may account for as much as 50-60% of the mucin-stimulating activity of lung fluids in allergic airway disease.