European Respiratory Journal

We investigated the relationship between airway calibre and the dose and distribution of inhaled aerosol in ten normal and six asthmatic subjects. Subjects inhaled saline aerosol containing 99mTcO4 delivered from a nebulizer connected to a dosimeter, and the lung fields were scanned with a gamma-camera. Right lung dose (RLD) was calculated as percentage of total dose. Intrapulmonary distribution was measured as penetration index (PI) (peripheral zone counts/central zone counts). Asthmatics had a significantly lower PI than normal subjects and there was a linear relationship between PI and baseline specific airway conductance (sGaw, p less than 0.001), and forced expiratory volume in one second (FEV1, p less than 0.05). After bronchodilatation with salbutamol (delta sGaw 101 +/- 31%, mean +/- SEM), PI increased from 0.73 +/- 0.11 to 1.09 +/- 0.15 (p less than 0.05); after bronchoconstriction with methacholine (delta sGaw 62.6 +/- 2.9%), PI decreased from 1.42 +/- 0.24 to 1.06 +/- 0.22 (p less than 0.05). Changes of PI were correlated with changes in sGaw and FEV1 (n = 20, p less than 0.001) but changes of RLD and changes in airway calibre were not. The distribution of inhaled aerosol, but not the dose, is largely dependent on airway calibre. The differences in PI between normal and asthmatic subjects may at best be explained by the differences in central airway calibre.

The Pollution Atmosphérique et Affections Respiratoires Chroniques (PAARC; Air Pollution and Chronic Respiratory Diseases) study provided the opportunity to examine the 25-yr mortality of 940 asthmatic adults drawn from a large population-based sample of 14,267 adults investigated during 1974–1976 in seven French cities.

Vital statistics were collected in 2001 for the whole population. Multivariate survival analysis was used to assess exact survival rates in asthmatics and nonasthmatics taking relevant confounders into account.

On average, the mortality rates obtained were 10.4 and 6.9 deaths·1,000 person-yrs⁻¹in asthmatics and nonasthmatics, respectively. On univariate analysis, asthma increased the relative risk (RR) of death by 1.48 (95% confidence interval (CI) 1.29–1.69). The association between asthma and death had an RR of 1.16 (95% CI 0.99–1.37) when age, sex, educational level, smoking habits, occupational exposure and forced expiratory volume in one second (FEV₁) were taken into account. FEV₁was an important contributive factor causing increased risk of death in both smokers and nonsmokers. For instance, in asthmatics, the numbers of deaths due to respiratory disease and cancer appeared excessive.

The present study suggests that asthmatics exhibit a higher risk of mortality.

This study was undertaken to investigate the reported association between Chlamydia pneumoniae and Mycoplasma pneumoniae infection and the expression of asthma-related symptoms. One hundred and eight children with asthma symptoms, aged 9-11 yrs, completed a 13 month longitudinal study. The children maintained a daily diary of respiratory symptoms and peak flow rates. When respiratory symptoms were reported an investigator was called and a nasal aspirate obtained. In total 292 episodes were reported. After the study 65 children provided samples when asymptomatic. The presence of infection was investigated by the polymerase chain reaction for C. pneumoniae and M. pneumoniae and C. pneumoniae secretory immunoglobulin A (IgA) was detected by amplified enzyme immunoassay. C. pneumoniae detections were similar between the symptomatic and asymptomatic episodes (23 versus 28%, respectively). Children who reported multiple episodes also tended to remain PCR positive for C. pneumoniae suggesting chronic infection (p< 0.02). C. pneumoniae-specific secretory-IgA antibodies were more than seven times greater in subjects who reported four or more exacerbations in the study compared to those who reported just one (p<0.02). M. pneumoniae was found in two of 292 reports and in two of 65 asymptomatic samples. In conclusion, chronic Chlamydia pneumoniae infection is common in schoolage children and immune responses to C. pneumoniae are positively associated with frequency of asthma exacerbations. We suggest that the immune response to chronic C. pneumoniae infection may interact with allergic inflammation to increase asthma symptoms. In contrast Mycoplasma pneumoniae was not found to be important in this study.

According to current guidelines, pulmonary arterial hypertension (PAH) is diagnosed when mean pulmonary arterial pressure (P̄_pa) exceeds 25 mmHg at rest or 30 mmHg during exercise. Issues that remain unclear are the classification ofP̄_pavalues <25mmHg and whetherP̄_pa>30 mmHg during exercise is always pathological.

We performed a comprehensive literature review and analysed all accessible data obtained by right heart catheter studies from healthy individuals to determine normalP̄_paat rest and during exercise. Data on 1,187 individuals from 47 studies in 13 countries were included. Data were stratified for sex, age, geographical origin, body position and exercise level.

P̄_paat rest was 14.0±3.3 mmHg and this value was independent of sex and ethnicity. RestingP̄_pawas slightly influenced by posture (supine 14.0±3.3 mmHg, upright 13.6±3.1 mmHg) and age (<30 yrs: 12.8± 3.1mmHg; 30–50 yrs: 12.9±3.0 mmHg; ≥50 yrs: 14.7±4.0 mmHg).P̄_paduring exercise was dependent on exercise level and age. During mild exercise,P̄_pawas 19.4±4.8 mmHg in subjects aged <50 yrs compared with 29.4±8.4 mmHg in subjects ≥50 yrs (p<0.001).

In conclusion, whileP̄_paat rest is virtually independent of age and rarely exceeds 20 mmHg, exerciseP̄_pais age-related and frequently exceeds 30 mmHg, especially in elderly individuals, which makes it difficult to define normalP̄_pavalues during exercise.

Các nghiên cứu gần đây đã chỉ ra rằng frusemide dạng hít có tác dụng bảo vệ chống lại nhiều kích thích co thắt phế quản trong bệnh hen suyễn, bao gồm tập thể dục, sương mù và dị ứng. Vì sự hoạt hoá tế bào mast dường như là một phần của quá trình co thắt phế quản do các kích thích này, nên có thể việc ức chế giải phóng chất trung gian chiếm phần nào hoặc toàn bộ hiệu quả ức chế của frusemide trong bệnh hen suyễn. Vì adenosine 5'-monophosphate (AMP) dạng hít là một kích thích khác gây ra co thắt phế quản bằng cách tăng cường giải phóng chất trung gian từ tế bào mast, chúng tôi đã điều tra khả năng của loại thuốc này trong việc đối kháng tác dụng trên đường thở của AMP và methacholine dạng hít trong một nghiên cứu ngẫu nhiên, có kiểm soát bằng giả dược, mù đôi ở 12 đối tượng mắc bệnh hen suyễn. Frusemide dạng hít (khoảng 28 mg) được dùng 5 phút trước khi thử thách làm tăng nồng độ kích thích của AMP và methacholine dạng hít cần thiết để giảm thể tích khí thở ra trong một giây (FEV) xuống 20% so với ban đầu từ 30 đến 96 mg/ml (p nhỏ hơn 0.01) và từ 1.1 đến 1.8 mg/ml (p nhỏ hơn 0.01), tương ứng. Sự bảo vệ mà frusemide mang lại chống lại AMP lớn hơn đáng kể so với methacholine (p nhỏ hơn 0.05). Dữ liệu này gợi ý rằng frusemide dạng hít có thể đóng vai trò như một chất đối kháng chức năng đối với co thắt cơ trơn, chẳng hạn như methacholine, có thể thông qua việc tăng cường tạo prostanoid. Hoạt động mạnh hơn của nó chống lại AMP và các kích thích co thắt phế quản khác, được cho là có liên quan đến chất trung gian tế bào mast, gợi ý về một hành động bổ sung trên chức năng tế bào mast có thể ở mức độ Ca++/Mg(++)-ATPase.

Oxit nitric (NO) chiếm phần lớn các tác động của yếu tố giãn nở nguồn gốc từ nội mô. Chúng tôi đã nghiên cứu xem liệu NO, khi được thêm vào khí hít, có thể gây ra tác động giãn phế quản tương tự như giãn mạch phổi đã được mô tả khi NO được sử dụng trong trường hợp co thắt động mạch phổi. Thỏ New Zealand White được đặt nội khí quản và thở máy với oxy 30% trong quá trình gây mê thần kinh. Methacholine (MCh) được phun sương với nồng độ tăng dần từ 0,5 đến 4,0 mg.ml-1, có hoặc không có sự hít thở 80 phần triệu (ppm) NO. Kỹ thuật bít chặt đường thở nhanh chóng trong quá trình bơm phồng với lưu lượng không đổi được sử dụng để đo lường cơ học hô hấp, cụ thể là kháng lực và độ giãn nở của hệ hô hấp. Phun sương methacholine không có hít thở NO làm tăng kháng lực từ 51 +/- 6 (trung bình +/- 95% khoảng tin cậy) lên 107 +/- 52 cmH2O.l-1.s ở nồng độ Mch 4 mg.ml-1. Trong khi hít thở NO, phun sương MCh không cho thấy sự gia tăng đáng kể về kháng lực. Áp lực oxy động mạch (PaO2) và độ giãn nở giảm cùng một mức độ trong thử thách methacholine, dù có hoặc không hít NO. Sự đóng của các đường thở nhỏ có thể là một cơ chế gây ra sự giảm PaO2 và độ giãn nở quan sát được. Điều này cho thấy rằng 80 ppm NO khi thêm vào khí hít điều chỉnh phản ứng tông màu ở đường thở trung ương đối với methacholine phun sương trong mô hình thử nghiệm ở thỏ này. Tuy nhiên, dường như nó có ít tác động hơn lên các đường thở ngoại biên.

We have recently shown that patients with sleep apnoea have thicker necks than non-apnoeic snoring controls. However, it was not clear whether this difference simply reflects the fact that apnoeic patients are more obese than the non-apnoeic ones, or whether it represents a preferential distribution of fat over the neck region compared to the abnormal region. We therefore measured the neck and abdominal circumferences in a large group of 670 patients suspected of having sleep apnoea, all of whom had full nocturnal polysomnography, including measurement of snoring. We divided these patients into apnoeic and non-apnoeic groups based on the apnoea/hypopnoea index (AHI) of 10. Apnoeic patients had significantly higher body mass index (BMI), neck, and abdominal circumferences than non-apnoeic controls. We then matched apnoeic and non-apnoeic patients exactly, one-for-one for BMI and age; this procedure left us with 156 patients in each group. Abdominal circumferences were similar, but the neck circumference was significantly higher in apnoeic patients (41.2 +/- 3.5 cm vs 39.1 +/- 3.7 cm, p less than 0.0001). Multiple stepwise linear regression analysis revealed that neck circumference and BMI correlated significantly with apnoea (multiple R2 = 0.27, p less than 0.001) and snoring (multiple R2 = 0.19, p less than 0.001). We conclude that obese patients with sleep apnoea have fatter necks than equally obese non-apnoeic snorers, and that the neck circumference could be a significant determinant of apnoea and snoring.

The purpose of our study was to explore the diagnostic accuracy of different methods of scoring night time recording of respiratory variables (NTRRV) for the diagnosis of the sleep apnoea-hypopnoea syndrome (SAHS). Within a 2 week period, we performed a partially attended night time recording of respiratory variables and a full polysomnography (PSG) for reference in patients with suspected SAHS. Night time recording of respiratory variables was carried out using equipment which records, and continuously displays on a monitor, oximetry, airflow, chest and abdominal motion and body position. Night time recording of respiratory variables was scored manually and automatically, according to different combinations of the parameters described previously. Full polysomnography was performed in the Sleep Laboratory following conventional standards. Thirty six patients were studied. Visual analysis and different automatic scoring profiles of night time recording of respiratory variables were compared to full polysomnography in terms of agreement, sensitivity and specificity. Visual scoring of night time recording of respiratory variables gave the finest agreement-sensitivity-specificity relationship. Automatic scoring of nighttime recording of respiratory variables showed a trend to underestimate the apnoea-hypopnoea index (AHI) with respect to full polysomnography due mainly to underrecognition of hypopnoeas. Agreement-sensitivity-specificity relationships of automatic night time recording of respiratory variables with respect to full polysomnography varied depending on the automatic profile used. Some had a good agreement and sensitivity whilst others had a good specificity. These findings show that visual scoring of night time recording of respiratory variables is the most accurate method of analysis when compared to full polysomnography. The usefulness of the automatic methods of scoring of respiratory variables depends on the end-point chosen and is not reliable enough to be used in all situations. Night time recording of respiratory variables represents a real complement to conventional full polysomnography in clinical practice.

The advantage of being a National Referral Centre for patients with suspected obstructive sleep apnoea (OSA) was used to seek clinical factors predictive of OSA, and thus determine if the number of polysomnography tests required could be reduced. Patients were mainly primary referrals, from an island population of 3.5 million. Two hundred and fifty consecutive patients underwent clinical assessment, full polysomnography, and a detailed self-administered questionnaire. This represents one of the largest European studies, so far, utilizing full polysomnography. Fifty four percent (n = 134) had polysomnographic evidence of OSA (apnoea/hypopnoea index (AHI) > or = 15 events.h-1 sleep). Patients with OSA were more likely to be male, and had a significantly greater prevalence of habitual snoring, sleeping supine, wakening with heartburn, and dozing whilst driving. Alcohol intake, age and body mass index (BMI) were significant independent correlates of AHI. After controlling for BMI and age, waist circumference correlated more closely with AHI than neck circumference among males, while the opposite was true among females. No single factor was usefully predictive of obstructive sleep apnoea. However, combining clinical features and oximetry data, where appropriate, approximately one third of patients could be confidently designated as having obstructive sleep apnoea or not. The remaining two thirds of patients would still require more detailed sleep studies, such as full polysomnography, to reach a confident diagnosis.

We have studied the predictive importance of neck circumference, obesity, and several radiographic pharyngeal dimensions for obstructive sleep apnoea (OSA), in 66 patients. OSA was quantified as the mean hourly number of greater than 4% dips in arterial oxygen saturation during sleep. Neck circumference (correlation coefficient (r) = 0.63, 95% confidence interval (C.I.) 0.46-0.76), obesity index (r = 0.54, 95% C.I. 0.39-0.69), hyoid position (r = 0.40, 95% C.I. 0.17-0.59), soft palate length (r = 0.31, 95% C.I. 0.08-0.51), and hard palate-to-spine angle (r = 0.29, 95% C.I. 0.04-0.49), correlated significantly with saturation dips in single regression analysis. In stepwise multiple linear regression analysis (saturation dip rate as the dependent variable), only neck size and retroglossal space were significant independent correlates (total r2 = 0.42, 95% C.I. 0.22-0.61, p less than 0.0001). We conclude that the relationships between general obesity, hyoid position, soft palate length, and OSA are probably secondary to variation in neck circumference.