Although the role of contractile function in the airways is controversial, there is general consensus on the importance of airway smooth muscle (ASM) as a therapeutic target for diseases characterized by airway obstruction, such as asthma or chronic obstructive pulmonary disease. Indeed, the use of bronchodilators to relax ASM is the most common and effective practice to treat airflow obstruction.

Excessive pathologic bronchoconstriction may originate from primary alterations of ASM mechanical function and/or from the effects exerted on ASM function by disease processes, such as inflammation and remodeling. An in depth knowledge of the potentially multiple mechanisms that distinctively regulate primary and secondary alterations in ASM contractile function would be essential for the development of new therapeutic approaches aimed at preventing the occurrence or reducing the severity of bronchoconstriction. The present review discusses studies that have addressed the mechanisms of altered ASM contractile function in models of airway hyperresponsiveness. Although not comprehensively, in the present review, animal models of intrinsic airway hyperresponsiveness, normal ontogenesis, and allergic sensitization are analyzed in the attempt to summarize the current knowledge on regulatory mechanisms of ASM contractile function in health and disease.

Studies in human ASM and the need for additional models to understand contractile function in the airways are also discussed.

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Background: Exercise-induced pulmonary arterial hypertension (EIPAH) is associated with reduced peak exercise cardiac output (CO) and aerobic capacity (peak O(2) ). We investigated the validity of the encouraged six-minute walk test (6MWT) to identify exercise limitation and estimate aerobic capacity in subjects with EIPAH.

Methods: Seventeen subjects with EIPAH (56 ± 14 years, 15 females) and 20 healthy controls (57 ± 13 years, 19 females) underwent two encouraged 6MWTs and a symptom-limited cardiopulmonary exercise test (CPET). To measure central haemodynamics, subjects with EIPAH performed the CPET with a pulmonary artery catheter in situ.

Results: Compared with controls, subjects with EIPAH had reduced peak O(2) (1.2 ± 0.4 vs 1.7 ± 0.5, L/min, P < 0.01), six-minute walk distance (6MWD) (575 ± 86 vs 669 ± 76m, P < 0.001) and six-minute walk work (6MWW) (39 ± 11 vs 45 ± 7 km.kg, P < 0.01). In subjects with EIPAH, there was a moderate correlation between 6MWD and peak O(2) (r= 0.72, P < 0.01) and a strong correlation between 6MWW and peak O(2) (r= 0.86, P < 0.001). There were significant correlations between 6MWD and peak CO (r= 0.59, P < 0.05), and between peak O(2) and peak CO (r= 0.55, P < 0.05). Peak heart rate was similar in the CPET and 6MWT in subjects with EIPAH (133 ± 15 vs 133 ± 19 beats/minute, P= 0.8).

Conclusions: The encouraged 6MWT identifies reduced exercise capacity and provides a valid estimate of aerobic capacity in EIPAH.

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Adolescents with severe allergies are at particular risk of severe and fatal anaphylactic reactions. Epinephrine (adrenaline) is known to be under-utilized by teenagers.

Objective We sought to gain knowledge of adolescents' attitudes towards and experience of epinephrine auto-injectors in order to inform improvements in patient education. Methods A qualitative study of adolescents in Scotland, UK with a history of anaphylaxis and their parents. In-depth interviews explored adolescents' accounts of anaphylactic reactions, including issues related to using epinephrine auto-injectors. Focus groups with adolescents and parents were used to discuss interventions to improve adolescent self-management of anaphylaxis.

Results Twenty-six adolescents and 28 parents were interviewed. Eight adolescents and 10 parents participated in separate focus groups. Most adolescents had not used the auto-injector in an anaphylactic emergency. We identified multi-faceted barriers to use, including: failure to recognize anaphylaxis; uncertainty about auto-injector technique and when to administer it; fear of using the auto-injector. Most adolescents reported carrying auto-injectors some of the time, though several found this inconvenient due to the size; only one reported non-use of an auto-injector because it had not been carried.

Conclusion and Clinical Relevance Adolescents and parents reported under-use of epinephrine auto-injectors. Carriage is insufficient to ensure that auto-injectors are used. Barriers to use are multiple and complex, and unlikely to be overcome using simple educational interventions. Auto-injector training currently offered is often inadequate preparation for an emergency. A more comprehensive approach is needed, addressing the psychosocial dimensions of anaphylactic emergencies as well as treatment. Training should ideally be provided by specialist allergists or nurses, but can also be provided and reinforced in primary care.

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Good control of allergic rhinitis (AR) in children is desirable because it is associated with diseases such as asthma. The aim of this analysis of the PETRA study was to characterise its diagnosis and treatment in Spanish children.

METHODS: Data were analysed for paediatric patients (age 5-17 years, inclusive) included in the PETRA study, which included consecutive patients with allergic rhinitis attending respiratory specialists throughout Spain. Demographic information, disease characteristics (duration, severity according to the Allergic Rhinitis and its Impact on Asthma [ARIA] classification), diagnostic procedures, treatments and physicians' attitudes to treatment were recorded.

RESULTS: Of the original sample of 1043 patients, 260 children were included (mean age, 11.7 years; 56.2% boys; 61.9% allergic to house dust mites (HDM) and 38.1% allergic to grass pollen). By ARIA classification, 180/260 (69.4%) had persistent AR and 176/280 (63%) had moderate disease. Asthma was reported in 89/161 (55%) with HDM allergy and 44/99 (45%) with grass pollen allergy. Symptomatic treatment was prescribed in 98.5%, although disease control had been no better than poor in 57.3%. Allergen specific immunotherapy was administered to 56.9%, and was used more often for HDM AR. When asked why specific immunotherapy was not prescribed, two-thirds of the investigators preferred a wait-and-see approach, prescribing immunotherapy if symptoms worsened or asthma developed.

CONCLUSIONS: Paediatric patients treated by specialists for allergic rhinitis have moderate or severe disease. Symptomatic treatment was extensively prescribed but often did not achieve good disease control. Many specialists preferred a wait-and-see approach before prescribing immunotherapy.

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