Resistance In Respiratory Tract Research Articles

Role of nitrous acid in the association between nitrogen dioxide and asthma symptoms: effect of nitrous acid exposure on specific airway resistance in guinea pigs

Epidemiological evidence regarding the effects of nitrogen dioxide (NO2) on asthma and chronic obstructive pulmonary disease (COPD) is inconclusive because NO2 assays measure nitrous acid (HONO) as NO2. Epidemiological study using separate measurements of indoor HONO and NO2 suggests that indoor HONO levels are associated with decrease in lung function, and HONO exposure experiment in rats suggests that HONO adversely affects respiratory function more than NO2. Effects of NO2 on respiratory tract resistance have not been observed in rats but have been observed in guinea pigs, including baseline specific airway resistance (sRaw). The present study aimed to investigate the effects of HONO exposure on baseline sRaw in guinea pigs. Eighteen male Hartley guinea pigs were divided into Groups C, M, and H (n = 6 per group) and exposed to HONO at three concentrations, respectively, 24 h/d for 7 weeks. Double-flow plethysmography was used to measure the sRaw once a week and grade respiratory waveforms, indicating increased airway resistance. The experiment was performed twice. Mean HONO concentrations of two experiments in Groups C, M, and H were 0.02, 0.66, and 3.43 parts per million (ppm). The sRaw increased significantly in Groups H and M compared with sRaw in Group C, and in a concentration-dependent manner after the 4th week of HONO exposure. Increased airway resistance was observed in 50% of animals in Group M and 100% of animals in Group H in some weeks. However, in some animals from Group M, increased airway resistance was observed earlier than the airway resistance increases observed in all animals in Group H. These sRaw results suggest that HONO affects asthma symptoms or COPD, at a lowest observed adverse effect level (LOAEL) of < 0.66 ppm. HONO may affect baseline sRaw after shorter exposure periods and at lower concentrations compared with the reported effects of NO2. The present results suggest that HONO is the most important nitrogen oxide affecting asthma and COPD indoors, and that HONO may be the causative agent in the association between NO2 and asthma symptoms in epidemiological studies.

Effect of mouth closure on upper airway obstruction in patients with obstructive sleep apnoea exhibiting mouth breathing: a drug-induced sleep endoscopy study.

Snoring and obstructive sleep apnoea (OSA) exhibit multifactorial aetiologies; mouth breathing increases airway obstruction and upper respiratory tract resistance. Of the many published studies, few have evaluated sleeping subjects. We explored how mouth breathing affected the upper respiratory tract anatomy and OSA during sleep. Eighteen patients with OSA, confirmed via full-night polysomnography, were enrolled in this study. We performed drug-induced sleep endoscopy (DISE) and defined obstruction sites before and after mouth closure using commercial mouth strips. We evaluated obstruction sites in two ways, i.e. by grading obstructions using our DISE grading system and measuring the affected areas. Patients who improved by at least one DISE grade were defined as responders. Areas were measured based on DISE videos analysed using ImageJ software. The apnoea-hypopnoea index (AHI) and body mass index (BMI) were recorded. Based on the DISE grade, 40% (7/18) of patients showed obstruction site improvement. When assessed areally, the mean number of pixels improved significantly at both the retropalatal (p = 0.045) and retrolingual (p = 0.019) levels. However, DISE non-responders exhibited no areal improvements. Responders and non-responders did not differ significantly in terms of AHI or BMI (both p < 0.05). Mouth closure improves or at least does not lead to further deterioration of the upper airway. Improvements were evident at the retropalatal and especially retrolingual levels. Neither the BMI nor the AHI differed between the two groups. However, responders tended to have a higher AHI than non-responders (39.4 vs. 32.8events/h).

Assessment of functional tests on determining resistance of respiratory tract in patients with bronchial asthma, COPD and their combination.

The mechanical properties of the respiratory tract (including airway resistance) is an important indicator of pulmonary function, and definition of resistance is used to diagnose and monitor obstructive lung diseases. This study was performed in order to evaluate and compare functional results of tests to determine the resistance of the airways in patients with asthma, chronic obstructive pulmonary disease and their combination. The study involved 191 patients: with asthma (n=34), with COPD (n=17) and their combination (n=140). Patients underwent bodyplethysmography and impulse oscillometry. A statistically significant correlation of medium strength between parameters of the total resistance, determined with the help of bodyplethysmography and impulse oscillometry, r=0.57, p&lt;0.001. According to ROC-analysis, the best point of distribution of normal and pathological parameters of impulse oscillometry (R5Hz) as a diagnosis of increased respiratory resistance is 130% and higher from the proper values. The area under the ROC curve is 0.807. When interpreting the results of impulse oscillometry in patients with asthma, COPD and their combination, R5Hz level equal to or exceeding 130% of the proper values is proposed to be regarded as a sign of an increased respiratory resistance with sensitivity of technique – 64.0%, specificity – 87.5% and prognostic value of the positive result - 98.2%.

Vagotomy reverses established allergen-induced airway hyperreactivity to methacholine in the mouse

We evaluated the role of vagal reflexes in a mouse model of allergen-induced airway hyperreactivity. Mice were actively sensitized to ovalbumin then exposed to the allergen via inhalation. Prior to ovalbumin inhalation, mice also received intratracheally-instilled particulate matter in order to boost the allergic response. In control mice, methacholine (i.v.) caused a dose-dependent increase in respiratory tract resistance (RT) that only modestly decreased if the vagi were severed bilaterally just prior to the methacholine challenge. Sensitized and challenged mice, however, manifested an airway reactivity increase that was abolished by severing the vagi prior to methacholine challenge. In an innervated ex vivo mouse lung model, methacholine selectively evoked action potential discharge in a subset of distension-sensitive A-fibers. These data support the hypothesis that the major component of the increased airway reactivity in inflamed mice is due to a vagal reflex initiated by activation of afferent fibers, even in response to a direct (i.e., smooth muscle)-acting muscarinic agonist.

To investigate the prevention of OM-85 on bronchiectasis exacerbations (iPROBE) in Chinese patients: study protocol for a randomized controlled trial.

BackgroundNon-cystic fibrosis bronchiectasis is characterized by the irreversible dilatation of the medium-sized bronchi as a result of airway injury from recurrent or chronic inflammation and lower respiratory tract infections. Bronchiectasis airways are commonly colonized with bacterial species. Infections of the airways play important role in bronchiectasis exacerbations. The non-specific prevention of recurrent airway infections by immunostimulating agents has gained growing interest. OM-85, consisting of extracts of eight kinds of bacteria important in respiratory infections, could support the respiratory tract resistance to the pathogens. OM-85 has been shown to be a benefit by decreasing the risk of acute exacerbation of chronic obstructive pulmonary disease (COPD) in several perspective clinical trials. Exacerbation of bronchiectasis substantially contributes to a more rapid decline in lung function, reduced quality of life, and healthcare costs. In this context, we plan to conduct a clinical trial to investigate the PReventive effect of OM-85 on Bronchiectasis Exacerbation in Chinese patients (iPROBE).Methods/DesignThis study is designed as a prospective, randomized, double blind, placebo-controlled multicenter trial. A total of 244 patients with bronchiectasis, who have had at least one exacerbation of bronchiectasis in the previous year, will be included. The subjects will randomly receive two courses of 7 mg of OM-85 or a matching placebo. The treatment dose of OM-85 will be one daily capsule taken orally for 10 days each month for 3 consecutive months at the beginning of the study, followed by 3 months of no drug. This schedule will repeat until the patient has been seen for one year.DiscussionWe will investigate whether long-term treatment with an oral immunostimulant (OM-85) could decrease exacerbations of bronchiectasis over a one-year period. We will also assess other relevant outcomes, including the rate of event-based exacerbation, lung function parameters, and total scores judged by the St George’s respiratory questionnaire, Leicester cough questionnaire, and inflammatory index. We hope that this study will provide new information on the preventive effects of OM-85 on bronchiectasis exacerbations and will address a knowledge gap for this understudied disease.Trial registrationThis study is registered at http://www.clinicaltrials.gov (identifier NCT01968421) on 19 October 2013.

Relevance of the expression of CTNNAL1 and the resistance of respiratory tract in rat with airway hyperresponsiveness

To observe the relation between the expression of CTNNAL1 and the airway resistance in rats with airway hyperresponsiveness. Thirty Wister rats were randomly divided into 5 groups: a normal control group, a 2 d ozone attack group, a 4 d ozone attack group, a 6 d ozone attack group, and a 6 d ozone attack+2 d dexamethasone treatment group (6 rats in each group). The distribution of CTNNAL1 was observed by in situ hybridization; the expression of CTNNAL1 was detected by fluorescence quantitative RT-PCR; the airway resistance was detected in by Buxco pulmonary function analysis system; and the relevance of the expression of CTNNAL1 and the resistance of respiratory tract in rat with airway hyperresponsiveness were analyzed. CTNNAL1 was distributed in bronchial epithelial cells, goblet cells, endothelial cells, and the alveolar wall. With the increase of the ozone attack, the expression of CTNNAL1 mRNA gradually reduced, the airway hyperresponsiveness was aggravated, and the airway resistance was increased. During airway hyperresponse, the reduction of CTNNAL1 mRNA can increase the airway resistance. There is a negative correlation between the reduction of CTNNAL1 mRNA and the airway hyperresponsiveness. CTNNAL1 is an adhesion molecule related to airway hyperresponsiveness susceptibility.

Impact of Septoplasty on Mean Platelet Volume Levels in Patients With Marked Nasal Septal Deviation

Nasal septal deviation (NSD) is a very common cause of recurrent and chronic nasal obstruction. Chronic nasal obstruction leads to increased upper respiratory tract resistance, and also upper respiratory tract resistance leads to chronic hypoxia and hypercarbic because of alveolar hypoventilation. Chronic hypoxia and hypercarbia show tendency for hypercoagulopathy.Mean platelet volume (MPV), the most commonly used measure of platelet size, is a potential marker of platelet reactivity. Large platelets that contain more dense granules are enzymatically and metabolically more active and have greater prothrombotic potential. In previous studies, increased MPV was demonstrated in hypertension, unstable angina pectoris, myocardial infarction, stroke, and obstructive sleep apnea.We aimed to determine whether MPV levels are elevated in patients with marked NSD (MNSD) compared with healthy controls. In addition, we tried to find out the effect of nasal septoplasty on MPV levels. We found that the MPV levels were significantly higher in the MNSD group than in the control healthy group, and also we found that MPV levels were significantly decreased in the MNSD group after septoplasty operation.In conclusion, in our knowledge, this is the first study investigating MPV levels in patients with MNSD. Increased platelet activation may be related to increase the cardiovascular risk in patients with MNSD. Our results suggest that MPV, a determinant of platelet activation, is elevated in patients with MNSD, and the increase in MPV levels of the cases with MNSD could be treated by septoplasty.

Exposure testing with powdered gloves in 60 health care workers with latex allergy

Type 1 sensitization to natural rubber latex occurs in up to 22% of health care workers. Most sensitizations are due to the use of powdered latex gloves. Work place-associated exposure tests were performed to ascertain how frequently persons who developed breathing difficulties, rhinitis/conjunctivitis or obstructive respiratory tract illness when using powdered latex gloves are allergic to latex. 60 persons (48 women and 12 men; mean age 29 +/- 7 years) with type 1 sensitization to natural rubber latex were studied. The past history was obtained through a questionnaire specially designed for those with latex allergy. Diagnostic measures included prick tests with different latex allergens, measuring the concentrations of total and latex-specific IgE and exposure trials, related to the work place, with powdered vinyl and latex gloves. The prick tests with various latex allergens produced significant skin reactions in 59 subjects, 58 had latex-specific IgE antibodies (0.47 kU/l- > 100 kU/l). Exposure tests with powdered latex gloves produced rhinitis in 55 and conjunctivitis in 38 persons, urticaria in 3 and cough in 19. Whole-body plethysmography demonstrated a significant rise in respiratory tract resistance in 13, a reduction in 1-second expiratory volume of at least 20% in 15. Abnormal values in both tests were noted in 8 subjects. The breathing difficulty reported by all subjects was in most cases due not to bronchial obstruction but to obstructed nasal breathing. In cases with breathing difficulty on exposure to latex gloves a latex allergy should be considered as the cause. Powdered latex gloves present a danger to health care personnel and should no longer be used.

Upper Respiratory Tract Resistance to Influenza Infection Is Not Prevented by the Absence of Either Nasal-Associated Lymphoid Tissue or Cervical Lymph Nodes

The murine nasal-associated lymphoid tissue (NALT) and cervical lymph nodes (CLN) are involved in the generation of local immune responses within the upper respiratory tract (URT). However, their involvement in these responses does not imply the necessity for resistance to URT infections. We surgically removed NALT or CLN to address the necessity of these lymphatic tissues for the development of a local protective immune response after a URT influenza infection. No histological evidence of the re-establishment of either tissue was detected after surgery and the subsequent infection. Removal of NALT did not elicit changes in serum or nasal mucosa-associated influenza-specific Ig levels. However, increases in PR8-specific serum IgG and nasal mucosa-associated IgA were detected after removal of CLN. Recruitment of influenza-specific CD4 T cells into the nasal mucosa was not altered by removal of NALT. The removal of NALT or CLN did not alter the recruitment of influenza-specific CD8 T cells into the URT. However, increased levels of influenza-specific CD8 T cells were observed in the tracheal-bronchial lymph nodes after CLN surgery. The rate of viral clearance from nasal mucosa and lungs was not altered by removal of NALT or CLN. These studies demonstrate that despite the participation of NALT and CLN in the generation of local immunity to influenza infections, neither tissue is essential for the development of protective immunity and viral clearance in URT.

Inhaled Nitric Oxide Effects on Lung Structure and Function in Chronically Ventilated Preterm Lambs

Inhaled nitric oxide (iNO) can reverse neonatal pulmonary hypertension and bronchoconstriction and reduce proliferation of cultured arterial and airway smooth muscle cells. To see if continuous iNO from birth might reduce pulmonary vascular and respiratory tract resistance (PVR, RE) and attenuate growth of arterial and airway smooth muscle in preterm lambs with chronic lung disease. Eight premature lambs received mechanical ventilation for 3 weeks, four with and four without iNO (5-15 ppm). Four term lambs, mechanically ventilated without iNO for 3 weeks, served as additional control animals. PVR and RE were measured weekly. After 3 weeks, lung tissue was processed for quantitative image analysis of smooth muscle abundance around small arteries (SMart) and terminal bronchioles (SMtb). Radial alveolar counts were done to assess alveolar number. Endothelial NO synthase (eNOS) protein in arteries and airways was measured by immunoblot analysis. At study's end, PVR was similar in iNO-treated and untreated preterm lambs; PVR was less in iNO-treated preterm lambs compared with term control animals. RE in iNO-treated lambs was less than 40% of RE measured in preterm control animals. SMart was similar in iNO-treated and both groups of control lambs; SMtb in lambs given iNO was significantly less (approximately 50%) than in preterm control animals. Radial alveolar counts of iNO-treated lambs were more than twice that of preterm control animals. eNOS was similar in arteries and airways of iNO-treated preterm lambs compared with control term lambs. iNO preserves structure and function of airway smooth muscle and enhances alveolar development in preterm lambs with chronic lung disease.

Improving the quality of health care: using international collaboration to inform guideline programmes by founding the Guidelines International Network (G-I-N)

Clinical practice guidelines are regarded as powerful tools to achieve effective health care. Although many countries have built up experience in the development, appraisal, and implementation of guidelines, until recently there has been no established forum for collaboration at an international level. As a result, in different countries seeking similar goals and using similar strategies, efforts have been unnecessarily duplicated and opportunities for harmonisation lost because of the lack of a supporting organisational framework. This triggered a proposal in 2001 for an international guidelines network built on existing partnerships. A baseline survey confirmed a strong demand for such an entity. A multinational group of guideline experts initiated the development of a non-profit organisation aimed at promotion of systematic guideline development and implementation. The Guidelines International Network (G-I-N) was founded in November 2002. One year later the Network released the International Guideline Library, a searchable database which now contains more than 2000 guideline resources including published guidelines, guidelines under development, "guidelines for guidelines", training materials, and patient information tools. By June 2004, 52 organisations from 27 countries had joined the network including institutions from Oceania, North America, and Europe, and WHO. This paper describes the process that led to the foundation of the G-I-N, its characteristics, prime activities, and ideas on future projects and collaboration.

Antimicrobial Resistance in Respiratory Tract Streptococcus pneumoniae Isolates: Results of the Canadian Respiratory Organism Susceptibility Study, 1997 to 2002

Antimicrobial Resistance in Respiratory Tract <i>Streptococcus pneumoniae</i> Isolates: Results of the Canadian Respiratory Organism Susceptibility Study, 1997 to 2002

Prevalence of Antimicrobial Resistance in Respiratory Tract Isolates of Streptococcus pneumoniae : Results of a Canadian National Surveillance Study

From October 1997 to November 1998, 1,180 respiratory tract isolates of Streptococcus pneumoniae were collected from 18 medical centers in 9 of the 10 Canadian provinces. Penicillin-intermediate and -resistant isolates occurred at rates of 14.8 and 6.4%, respectively, and these rates varied considerably by geographic region. Trimethoprim-sulfamethoxazole, tetracycline, and macrolide rates of nonsusceptibility were 12.2, 10.6, and 8.0 to 9.3%, respectively. The most potent agents studied were newer fluoroquinolones.

Distinct effects of Broncho-Vaxom (OM-85 BV) on gp130 binding cytokines

BACKGROUNDBroncho-Vaxom (OM-85 BV) is known to support respiratory tract resistance to bacterial infections. In vivo and in vitro studies in animals and humans have shown that the action of the...

Prevalence of antimicrobial resistance in respiratory tract isolates of Streptococcus pneumoniae: results of a Canadian national surveillance study. The Canadian Respiratory Infection Study Group.

From October 1997 to November 1998, 1,180 respiratory tract isolates of Streptococcus pneumoniae were collected from 18 medical centers in 9 of the 10 Canadian provinces. Penicillin-intermediate and -resistant isolates occurred at rates of 14.8 and 6.4%, respectively, and these rates varied considerably by geographic region. Trimethoprim-sulfamethoxazole, tetracycline, and macrolide rates of nonsusceptibility were 12.2, 10.6, and 8.0 to 9.3%, respectively. The most potent agents studied were newer fluoroquinolones.

Patterns of fetal perinasal fluid flow in cases of congenital diaphragmatic hernia

OBJECTIVE(S): Our purpose was to expand the previous reported series of observations of fetal perinasal fluid flow in cases of antenatally diagnosed congenital diaphragmatic hernia, characterize the timing parameters of the fetal breath cycle, and define the relationship of fetal perinasal fluid flow and the diaphragmatic component of fetal breathing movements. Our hypothesis was that characteristics of diaphragm-related and nondiaphragm-related perinasal fluid flow and other breath cycle characteristics differ in cases of congenital diaphragmatic hernia compared with controls. STUDY DESIGN: Fetal perinasal fluid flow velocity and fetal chest wall movements were studied in 24 cases of uncomplicated pregnancy, and flow was studied in 24 cases of antenatally diagnosed congenital diaphragmatic hernia at gestational ages ranging from 30 to 41 weeks. The examination of fetal perinasal fluid flow velocity was performed with use of an ultrasonography system applying color flow and spectral Doppler analysis. Breath-to-breath interval, time of inspiration, time of expiration, and peak inspiratory and expiratory velocities were determined for each type of perinasal flow. RESULTS: The study revealed that the time of expiration in cases of congenital diaphragmatic hernia at 30 to 36 and 37 to 41 weeks of gestation was significantly shorter than in cases of uncomplicated pregnancy. The ratio of time of inspiration and breath-to-breath interval in cases of diaphragmatic hernia was approximately 30% higher ( p = 0.001) at 30 to 36 weeks of gestation than in cases of uncomplicated pregnancy. The study also showed that in cases of congenital diaphragmatic hernia the expiratory peak velocity ratio at 30 to 36 weeks of gestation was significantly lower than in cases of uncomplicated pregnancy. CONCLUSIONS: We conclude that by Doppler ultrasonography measurements of fetal perinasal fluid flow, in cases of congenital diaphragmatic hernia, we can evaluate the timing parameters of fetal diaphragm-related breath cycles, the relationship of intraalveolar and intraamniotic pressures, and fetal upper respiratory tract resistance. Fetuses with diaphragmatic hernia spent significantly more time with diaphragm-nonrelated perinasal flow than did fetuses in cases of uncomplicated pregnancy, which can cause the increased loss of lung liquid and consequently be associated with pulmonary insufficiency in the early neonatal period. (Am J Obstet Gynecol 1997;176:807-13.)

Nasal airway impairment: The oral response in cleft palate patients

The purpose of this study was to assess the oral response to severe nasal airway impairment in patients with cleft palate. Inductive plethysmography was used to measure the percent of nasal breathing, and the pressure-flow technique was used to estimate nasal area in 15 persons with severe nasal airway impairment. Mean nasal area was 0.17 cm2, and the average percent of nasal breathing was 20%. Analysis revealed a strong correlation (0.87) between nasal size and percent of nasal breathing in this selected group. Modeling studies based on the mean values from the subjects' data indicated that the model "mouth" would have to open 0.5 cm2 to shunt 80% of the airflow orally, an amount equivalent to the mean value of the subjects' respiratory mode. More important, the extrapolated data revealed that upper-airway resistance decreased in the model from 8.7 cm H2O/L/sec to a level of 3.2 cm H2O/L/sec, which is an average value for healthy adults. These data support the concept that the mouth acts as a variable resistor to maintain an optimal respiratory tract resistance when the nasal airway is impaired.

In vitro and in vivo effect of mercury, lead and cadmium on the generation of chemiluminescence by human whole blood

A method based on the use of the luminogenic substance, luminol, was developed for measuring the respiratory burst induced by phorbolmyristate acetate in 4 μl of human whole blood. In vitro, the three cations, Hg 2+, Pb 2+ and Cd 2+ inhibit the peak luminescence response at concentrations higher than those usually found in blood of subjects exposed to these metals. Cadmium metallothionein, however, in a concentration range similar to that found in whole blood of workers exposed to cadmium strikingly reduces the respiratory oxidative burst. In workers exposed to inorganic lead or mercury vapour, no reduction of the chemiluminescence response of whole blood was observed while a slight but statistically significant reduction was found in whole blood from cadmium exposed workers. If a similar effect occurs in lung macrophages, it might decrease the respiratory tract resistance to infection.

Resistance of the respiratory tract of the chicken to Newcastle disease virus infection following vaccination: The effect of passively acquired antibody on its development

Vaccination of chickens with a live Newcastle disease virus (NDV) vaccine given intranasally or intramuscularly or an inactivated NDV vaccine given by the respiratory route induced variable degrees of resistance in the respiratory tract to challenge with an avirulent strain of NDV. An inactivated NDV vaccine given intramuscularly, however, induced little resistance, despite the high concentration of serum antibody that developed. When a live NDV vaccine was given to chicks with passively acquired antibody, serum antibody response was markedly inhibited, but no comparable inhibition of respiratory tract resistance could be demonstrated. The results suggest that the direct or indirect exposure of the respiratory tract tissues to viral antigen was necessary for the induction of resistance to infection in the respiratory tract.

The birth of asthma

“Conditioning” procedures involving reciprocal inhibition, altered perception associated with hypnosis etc. were successful in greatly reducing or eliminating asthma in many subjects. This was so whatever the trigger (including allergy) and in spite of the failure of previously given orthodox treatments. A small fraction of patients treated as above showed no improvement - some even being unable to collaborate in relaxing procedures. Forty such unresponsive patients were referred to me and investigated by psychiatric interview; in most cases a few further psychotherapeutic interviews and/or treatment with anti-depressants followed. Most showed suppressed depression or aggression. The majority improved markedly when the depression was relieved and/ or the expression of anger was facilitated. It was later suggested that the behaviour pattern of asthmatic breathing had, in these subjects, in some way been locked on to the affective state. In an attempt to explain these concomitant physiological and psychological phenomena, theories of the initiation of an attack will be discussed with emphasis on the relationship between bronchial mucosal capillary dilatation and bronchial smooth muscle contraction. The limitations and the surviving significance of the Dutch “heresy” regarding the initiation of the attack by the use of voluntary muscle, increasing intra-thoracic pressure and causing tracheal compression, will be critically examined. It will be argued that all the theories of initiation refer, in fact, to the immediate post-natal breathing pattern of an infant, whose first gasps of air have been shown to be exhaled against upper respiratory tract resistance without effective contraction of the vocal cords - giving rise to the specific ‘unvoiced’ birth cry. It will be noted that this innate reflex behaviour is associated with pulmonary capillary dilatation and the affects of fear, anger and depression which may be associated with birth. It will be suggested that the ‘first cry’ mechanism, switched briefly into play at birth, may subsequently not be totally extinguished but, in some individuals, revived as if ‘locked on’ to physiological states of pulmonary capillary dilatation (e.g. associated with allergy) or psychological states of anger or depression. The lack of extinction and ‘locking on’ of the abnormal breathing pattern may be the result of immensely intense affect associated with the particular individual's intra-uterine, birth canal and birth experience.