Impact of different breathing protocols on multiple-breath washout outcomes in children

BACKGROUND To standardize multiple-breath washout (MBW) measurements, 1L tidal volume (VT) protocols were suggested. The effect on MBW derived ventilation inhomogeneity (VI) indices is unclear. METHODS We compared VI indices from free breathing MBW at baseline to 1L VT MBW performed in triplicates in 35 children (20 with CF). Mean (range) age was 12.8 (7.0-16.7) years, weight 42 (20-64) kg and height 151 (117-170) cm. RESULTS Baseline lung clearance index (LCI) increased from mean (SD) 11.0 (2.2) to 13.0 (2.6), p=0.011, in CF and from 6.8 (0.5) to 7.7 (1.4), p=0.004, in controls. Moment ratio and Scond similarly increased. While change in VI indices was heterogeneous in individuals, decrease in functional residual capacity was most strongly associated with LCI increase. CONCLUSION MBW protocols strongly influence measures of VI. The 1L VT MBW protocol leads to overestimation of VI and is not recommended in children.

Effect of bacterial filter on measurement of interrupter resistance in preschool and school-aged children

BACKGROUND: The interrupter technique is increasingly used in preschool children to assess airway resistance (Rint). Use of a bacterial filter is essential for prevention of cross-infection in a clinical setting. It is not known how large an effect this extra resistance and compliance exert upon interrupter measurements, especially on obstructive airways and in smaller children. We aim to determine the contribution of the filter to Rint, in a sample of children attending lung function testing at an asthma clinic. METHODS: Interrupter measurements were performed according to ATS/ERS guidelines during quiet normal breathing at an expiratory flow trigger of 200 ml s(-1), with the child seated upright with cheeks supported and wearing a nose clip. A minimum of 10 interrupter measurements was made with and without a bacterial filter. Spirometric and plethysmographic tests were also performed. RESULTS: A small but significant difference (0.12 (95% CI 0.06-0.17) kPa s L(-1), P = 0.0002) with 2x SD of 0.34 kPa s L(-1) was observed between Rint with and without filter in 39 children, with a large spread. This difference was not dependent on Rint magnitude, age or height, nor on lung function parameters (effective resistance, forced expiratory volume in 1 sec, and maximal expiratory flow at 50% of expired vital capacity). CONCLUSIONS: A bacterial filter causes a small difference but is not clinically significant, with a wide spread comparable to the variability of the technique and recommended cut-offs for assessing repeatability and bronchodilation. Age, height or severity of obstruction need not be corrected for in general.

A 4-year study on clinical characteristics of children hospitalized with rotavirus gastroenteritis

Rotavirus (RV) is a frequent cause of severe gastroenteritis (GE) in children. With the licensure of new RV vaccines, data on the burden of disease are important regarding immunization strategies. We reviewed the medical records of children hospitalized with RV infection in our institution between July 2002 and March 2006. Relevant data were extracted in a standardized fashion from records of hospitalized children with a positive RV antigen test in a stool sample. Severity of disease was graded by the 20-point Vesikari score. Population data were obtained from the Federal Office of Statistics. Six hundred eighty-six RVGE were identified and records of 608 hospitalizations (in 607 children) were available. In 539 (89%) cases, RVGE was the primary reason for hospitalization and 69 (11%) were nosocomial infections; yearly peaks occurred between February and May. Cumulative incidence of RVGE was 26.7/1,000 children <3 years of age. Median age of 539 children (55.6% male) with primary RVGE was 1.4 years and median stay in the hospital for both community acquired and nosocomial RVGE was 4 days (interquartile range 3-5). Thirtypercent and 94% of RV hospitalizations were in children <1 and <3 years of age, respectively. Mean Vesikari score was 15 (range 6-20; 96% >11). Intravenous fluids were administered in 378 (70%) patients, 130 (24%) patients were rehydrated via nasogastral tube, and 31 (5.7%) received rehydration by mouth. RVGE causes a substantial burden in children with an estimated risk for hospitalization due to RVGE of one in 37 children <3 years of age.

Alternative outcomes for the multiple breath washout in children with CF

BACKGROUND The lung clearance index (LCI) measured by multiple-breath washout (MBW) has been proposed as an outcome for clinical trials; however, MBW is time consuming and LCI can be affected by breathing pattern. We aimed to evaluate moment ratios and abbreviated LCI in school-aged children with mild-to-moderate CF lung disease. METHODS Using existing data from three studies we assessed the sensitivity of moment ratios and abbreviated LCIs to (i) detect mild-to-moderate CF lung disease and (ii) detect treatment effects after 4weeks of hypertonic saline or dornase alfa inhalation. MBW was measured by respiratory mass spectrometry using 4% "sulphur hexafluoride as a tracer gas. RESULTS Compared to the traditional LCI, moment ratios and abbreviated LCIs were similarly sensitive to detect CF lung disease. Moment ratios consistently demonstrated treatment effects, whereas abbreviated LCIs were less sensitive. CONCLUSIONS Both moment ratios and abbreviated LCI are suitable to differentiate health from disease. Sensitivity is decreased for abbreviated LCIs in interventional studies in mild CF lung disease.