The measurement of lung volumes using body plethysmography: a comparison of methodologies.

Respir Care. 2012 Jul;57(7):1076-83

Authors: Borg BM, Thompson BR

Abstract
BACKGROUND: The statement of the American Thoracic Society and European Respiratory Society on the measurement of static lung volumes (SLV) suggests a preferred and alternate method for measuring and calculating SLV.
OBJECTIVE: To determine if differences in functional residual capacity (FRC), vital capacity (VC), residual volume (RV), and total lung capacity (TLC), obtained using preferred and alternate measurement and calculation methodologies, exist in a clinical setting.
METHODS: Patients attending for SLV at a hospital-based laboratory were recruited. Following spirometry, SLV was measured via body plethysmography, using the preferred and alternate methods in random order. Volumes were calculated using the preferred and alternate calculation methods. Subjects were classified according to standard ventilatory function interpretative strategies. Differences of the means between the measurement methods, and calculation methods were assessed.
RESULTS: One hundred eight data sets were analyzed. Significant, but small differences (< 150 mL) in the means for VC and TLC, and RV and TLC were found in the normal and restricted groups, respectively. No significant differences in SLV parameters were found in subjects with air-flow obstruction. Twelve of the 108 changed ventilatory function classification between methods, with the alternate method delivering a lower inspiratory capacity and TLC without a change in RV in 66% of this subgroup. Identical results were obtained when data were analyzed using both calculation methods.
CONCLUSIONS: Differences in FRC, VC, RV, and TLC obtained using the preferred and alternate measurement methodologies exist in the clinical setting in select classification groups and individuals. Differing calculation methods dependent on measurement method used may be unnecessary.

PMID: 22272788 [PubMed - indexed for MEDLINE]

Related Articles

Early administration of systemic corticosteroids reduces hospital admission rates for children with moderate and severe asthma exacerbation.

Ann Emerg Med. 2012 Jul;60(1):84-91.e3

Authors: Bhogal SK, McGillivray D, Bourbeau J, Benedetti A, Bartlett S, Ducharme FM

Abstract
STUDY OBJECTIVE: The variable effectiveness of clinical asthma pathways to reduce hospital admissions may be explained in part by the timing of systemic corticosteroid administration. We examine the effect of early (within 60 minutes [SD 15 minutes] of triage) versus delayed (>75 minutes) administration of systemic corticosteroids on health outcomes.
METHODS: We conducted a prospective observational cohort of children aged 2 to 17 years presenting to the emergency department with moderate or severe asthma, defined as a Pediatric Respiratory Assessment Measure (PRAM) score of 5 to 12. The outcomes were hospital admission, relapse, and length of active treatment; they were analyzed with multivariate logistic and linear regressions adjusted for covariates and potential confounders.
RESULTS: Among the 406 eligible children, 88% had moderate asthma; 22%, severe asthma. The median age was 4 years (interquartile range 3 to 8 years); 64% were male patients. Fifty percent of patients received systemic corticosteroids early; in 33%, it was delayed; 17% of children failed to receive any. Overall, 36% of patients were admitted to the hospital. Compared with delayed administration, early administration reduced the odds of admission by 0.4 (95% confidence interval 0.2 to 0.7) and the length of active treatment by 0.7 hours (95% confidence interval -1.3 to -0.8 hours), with no significant effect on relapse. Delayed administration was positively associated with triage priority and negatively with PRAM score.
CONCLUSION: In this study of children with moderate or severe asthma, administration of systemic corticosteroids within 75 minutes of triage decreased hospital admission rate and length of active treatment, suggesting that early administration of systemic corticosteroids may allow for optimal effectiveness.

PMID: 22410507 [PubMed - indexed for MEDLINE]

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Serologic allergic bronchopulmonary aspergillosis (ABPA-S): long-term outcomes.

Respir Med. 2012 Jul;106(7):942-7

Authors: Agarwal R, Garg M, Aggarwal AN, Saikia B, Gupta D, Chakrabarti A

Abstract
BACKGROUND AND AIM: ABPA is radiologically classified on the presence or absence of central bronchiectasis (CB) as ABPA-CB and serologic ABPA (ABPA-S) respectively. Few studies have described the follow-up of patients with ABPA-S. The aim of this retrospective study was to describe the outcomes of ABPA-S.
METHODS: Patients were diagnosed as ABPA-S if they met all the following criteria: asthma, immediate cutaneous hyperreactivity to Aspergillus fumigatus antigen, total IgE levels >1000 IU/mL, A. fumigatus specific IgE levels >0.35 kUA/L and normal HRCT of the chest. They were treated with glucocorticoids and followed up with history, physical examination, chest radiograph and total IgE levels every 6 weeks to 3 months. In addition, an annual spirometry and a biennial HRCT chest were performed in all patients.
RESULTS: Of the 55 patients with ABPA-S, 41 (17 men, 24 women; mean age, 38.3 years) consented for performance of repeat HRCT scans. The median duration of asthma prior to diagnosis of ABPA was six years. The duration of follow-up ranged from 24 to 77 months with the mean (SD) follow-up duration being 43.7 (10.1) months. There was improvement in FEV(1) but not the FVC values during the follow-up period (p values = 0.001 and 0.5 for FEV(1) and FVC respectively). There was no development of CB in any patient. Sixteen patients had a relapse during the follow-up period, and six patients were classified as glucocorticoid-dependent ABPA.
CONCLUSIONS: Although relapses are frequently seen, the long-term outcome of ABPA-S is good with no patient developing CB.

PMID: 22445696 [PubMed - indexed for MEDLINE]