Rint Measurements Research Articles

Relationship between baseline and post-bronchodilator interrupter resistance and specific airway resistance in preschool children

BackgroundThe assessment of airway function in preschool children can be done using simple measurement techniques such as interrupter resistance (Rint) or specific airway resistance (sRaw). ObjectiveThe aim of the study was to assess the relationship and the agreement between Rint and sRaw baseline measurements expressed in z-score and bronchodilator response (BDR) in accordance with the latest reference equations and recommended procedures. MethodsOne hundred thirty children aged 3 to 6 years old, referred to our pediatric pulmonary function test unit for assessment of airway function were consecutively included. Children performed baseline and post-bronchodilator measurements of Rint and sRaw. ResultsOne hundred twenty baseline measurements were obtained (98.7%) with both techniques. At baseline there was a strong correlation between Rint and sRaw z-score (r = 0.5, P < .01) despite the poor agreement (Cohen Kappa coefficient 0.09 [-0.08; 0.26]). The agreement for BDR was fair, with Cohen Kappa coefficient (95% IC) = 0.33 (0.13; 0.54). Children with poorly or partially controlled asthma had both higher baseline Rint and sRaw (P < .01), and higher post-bronchodilator mean change (P < .01), than children with well-controlled asthma. ConclusionThe poor agreement between the Rint and sRaw reference measurements demonstrates the lack of reliability of sole Rint or sRaw technique for airway obstruction diagnosis and the need to perform each technique concomitantly with BDR test. Other longitudinal and larger sample studies are needed to confirm the threshold value for a positive BDR, especially for sRaw.

Interrupter technique in infancy: Higher airway resistance and lower short-term variability in preterm versus term infants.

In preschool children, measurement of airway resistance using interrupter technique (Rint) is feasible to assess the degree of bronchial obstruction. Although some studies measured Rint in infancy, values of Rint and its variability in preterm infants are unknown. In this study, Rint and its variability was measured at infancy and compared between healthy term and preterm infants. High quality Rint measurements in term (n = 50) and preterm (n = 48) infants were obtained at postmenstrual age of 42-50 weeks in two study centers in Switzerland. Intra-measurement variability of Rint in one measurement and inter-measurement variability between two subsequent measurements was assessed by coefficient of variation (CV). Mean Rint in term infants was 4.2 ± (SD; 1.9) kPa · s · L-1 and in preterm infants was 5.6 ± (2.8) kPa · s · L-1 . Mean CV in term infants was 29.6 ± (14.9)% and in preterm infants was 20.2 ± (8.4)%. Rint was significantly lower (95%CI -2.31 to -0.38; P = 0.007) and CV significantly higher (95%CI 4.53-14.3; P < 0.001) in term compared to preterm infants. There were no differences in mean Rint and mean CV between the first and the second measurement obtained in a subgroup of term (n = 24, 48%) and preterm (n = 22, 45%) infants. Our results suggest that differences in airway mechanics between term and preterm infants can be assessed with the interrupter technique during early infancy. Before clinical application of Rint measurements in this age group, reasons underlying the variability of measurements should be further investigated.

Body fat mass distribution and interrupter resistance, fractional exhaled nitric oxide, and asthma at school-age

Obesity and asthma often coexist. We hypothesized that detailed body fat distribution measures might be more strongly associated than body mass index (BMI) with childhood asthma. We examined the associations of total body and abdominal fat measures with respiratory resistance (Rint), fractional exhaled nitric oxide (Feno), and risks of wheezing and asthma in school-aged children. In a population-based prospective cohort study among 6178 children aged 6years, we measured BMI, fat mass index, android/gynoid ratio, and preperitoneal and subcutaneous fat mass by physical examinations, dual-energy x-ray absorptiometry, and ultrasound, respectively. We performed Rint and Feno measurements, and assessed physician-diagnosed wheezing and asthma by questionnaires. A higher BMI was associated with a higher Rint (Zscore [95% CI], 0.06 [0.01-0.12]) and increased risk of wheezing (odds ratio [95% CI], 1.07 [1.00-1.14], per Z score BMI increase), but not with Feno or asthma. Ahigh fat mass index was associated with a higher Rint (Z score [95% CI], 0.40 [0.13-0.68]). Ahigh android/gynoid fat mass ratio was associated with a lower Feno (Sym% [95% CI], -9.8 [-16.3 to -3.4]), whereas a high preperitoneal fat mass was associated with a higher Feno (Sym% [95% CI], 6.5 [0.1-12.9]). Subcutaneous fat mass was not associated with any respiratory outcome. Studying detailed body fat distribution measures might provide better insight into the obesity-asthma paradigm.

Evaluation of Airway Resistance in Children with Juvenile Idiopathic Arthritis.

Background: Pneumonitis, pleuritis, and pulmonary interstitial infiltration have been described in patients with juvenile idiopathic arthritis (JIA). However, the pulmonary involvement of JIA is not often clinically apparent. There are few studies based on pulmonary function in children having only a diagnosis of JIA. The aim of the present study is to determine whether children with JIA have airway resistance and flow impairments measured by easily applied interrupter technique. Method: We performed interrupter resistance (Rint) measurements in children with JIA and in healthy control subjects who had no respiratory symptoms or diseases. Results: Fifty-eight children with the diagnosis of JIA (Mean age=12.5±2.75 years; range 7-17 years) and 33 healthy subjects (Mean age=11.8±2.62 years; range 6-16 years) were included in the study. The mean value of tidal peak flow during expiration measured by the interrupter technique was significantly lower in the JIA study group (0.73±0.11 L/s) compared to the healthy control group (0.79±0.08 L/s; p=0.01). Rint values measured during inspiration (Rintinsp) and during expiration (Rintexp) were higher in the JIA study group (Rintinsp=0.28±0.16 Kpa/L/s; Rintexp=0.30±0.50 Kpa/L/s) compared to the healthy control group (Rintinsp=0.26±0.11 Kpa/L/s; Rintexp=0.23±0.08 Kpa/L/s; p>0.05). There was also a positive correlation between C-reactive protein level and median expiratory interrupter resistance (Rintexp; r=0.50, p=0.005). Conclusion: The interrupter technique is a noninvasive and feasible technique and can be used to assess airway abnormalities in children with JIA who cannot successfully complete spirometry.

Evaluation of systematic assessment of asthma-like symptoms and tobacco smoke exposure in early childhood by well-child professionals: a randomised trial.

ObjectivesThis study aimed to evaluate the effectiveness of systematic assessment of asthma-like symptoms and environmental tobacco smoke (ETS) exposure during regular preventive well-child visits between age 1 and 4 years by well-child professionals.MethodsSixteen well-child centres in Rotterdam, the Netherlands, were randomised into 8 centres where the brief assessment form regarding asthma-like symptoms and ETS exposure was used and 8 centres that applied usual care. 3596 and 4179 children (born between April 2002 and January 2006) and their parents visited the intervention and control centres, respectively. At child’s age 6 years, physician-diagnosed asthma ever, wheezing, fractional exhaled nitric oxide (FeNO), airway resistance (Rint), health-related quality of life (HRQOL) and ETS exposure at home ever were measured. Linear mixed models were applied.ResultsNo differences in asthma, wheezing, FeNO, Rint or HRQOL measurements between intervention and control group were found using multilevel regression in an intention-to-treat analysis (p>0.05). Children of whom the parents were interviewed by using the brief assessment form at the intervention well-child centres had a decreased risk on ETS exposure at home ever, compared to children who visited the control well-child centres, in an explorative per-protocol analysis (aOR = 0.71, 95% CI:0.59–0.87).ConclusionsSystematic assessment and counselling of asthma-like symptoms and ETS exposure in early childhood by well-child care professionals using a brief assessment form was not effective in reducing the prevalence of physician-diagnosed asthma ever and wheezing, and did not improve FeNO, Rint or HRQOL at age 6 years. Our results hold some promise for interviewing parents and using information leaflets at well-child centres to reduce ETS exposure at home in preschool children.Trial RegistrationControlled-Trials.com ISRCTN15790308.

Evaluación de la medición de las resistencias pulmonares por técnica de interrupción

Pulmonary function tests allow an objective assessment of the degree of bronchial obstruction in collaborative subjects. The measurement of airway resistance using passive methods is very helpful in non-collaborative subjects. The objective of this study was to assess the applicability of measuring airway resistance by the interrupter technique (Rint) in pediatric subjects, determining its reproducibility, reliability and accuracy versus other techniques to measure airway resistance. Cross-sectional study in healthy children and in children with an obstructive airway disease, all aged 2-18 years old. The Rint was measured using a portable device and results were compared to airway resistance measured by oscillometry and plethysmography. The reproducibility of measurements and the infuence of the different outcome measures (use of mask or mouthpiece, cheek support, or nose clip) were assessed. Valid measurements were obtained in 82.6% of 460 children (47.6% younger than 7 years old). Reproducibility was very good (ICC= 0.9412; p <0.00001), and no differences were found among the measurements obtained at separate time intervals (0.75 ± 0.3 versus 0.74 ± 0.28; p= 0.435). None of the factors indicated before had an effect on the reproducibility of measurements. Resistance values obtained by plethysmography and oscillometry were higher than those obtained using the Rint, with a positive correlation between them. The higher the degree of airway obstruction, the worse the correlation with plethysmography. The Rint measurement is a plausible and reproducible technique, and has an adequate correlation with the resistance measurements obtained using oscillometry or plethysmography, thus making it useful for non-collaborative patients. In patients with airway obstruction, this technique could underestimate resistance, so it would be a hurdle to use it to follow-up subjects with a moderate to severe obstructive disease or in bronchial challenge tests.

Socioeconomic and Sociodemographic Factors Associated with Asthma Related Outcomes in Early Childhood: The Generation R Study

RationaleFew studies have analyzed the association of socioeconomic and sociodemographic factors with asthma related outcomes in early childhood, including Fraction of exhaled Nitric Oxide (FeNO) and airway resistance (Rint). We examined the association of socioeconomic and sociodemographic factors with wheezing, asthma, FeNO and Rint at age 6 years. Additionally, the role of potential mediating factors was studied.MethodsThe study included 6717 children participating in The Generation R Study, a prospective population-based cohort study. Data on socioeconomic and sociodemographic factors, wheezing and asthma were obtained by questionnaires. FeNO and Rint were measured at the research center. Statistical analyses were performed using logistic and linear regression models.ResultsAt age 6 years, 9% (456/5084) of the children had wheezing symptoms and 7% (328/4953) had asthma. Children from parents with financial difficulties had an increased risk of wheezing (adjusted Odds Ratio (aOR) = 1.63, 95% Confidence Interval (CI):1.18–2.24). Parental low education, paternal unemployment and child's male sex were associated with asthma, independent of other socioeconomic or sociodemographic factors (aOR = 1.63, 95% CI:1.24–2.15, aOR = 1.85, 95% CI:1.11–3.09, aOR = 1.58, 95% CI:1.24–2.01, respectively). No socioeconomic or gender differences in FeNO were found. The risks of wheezing, asthma, FeNO and Rint measurements differed between ethnic groups (p<0.05). Associations between paternal unemployment, child's sex, ethnicity and asthma related outcomes remained largely unexplained.ConclusionsThis study showed differences between the socioeconomic and sociodemographic correlates of wheezing and asthma compared to the correlates of FeNO and Rint at age 6 years. Several socioeconomic and sociodemographic factors were independently associated with wheezing and asthma. Child's ethnicity was the only factor independently associated with FeNO. We encourage further studies on underlying pathways and public health intervention programs, focusing on reducing socioeconomic or sociodemographic inequalities in asthma.

Reference values for airway resistance in newborns, infants and preschoolers from a Latin American population

Several studies have determined reference values for airway resistance measured by the interrupter technique (Rint) in paediatric populations, but only one has been done on Latin American children, and no studies have been performed on Mexican children. Moreover, these previous studies mostly included children aged 3 years and older; therefore, information regarding Rint reference values for newborns and infants is scarce. Rint measurements were performed on preschool children attending eight kindergartens (Group 1) and also on sedated newborns, infants and preschool children admitted to a tertiary-level paediatric hospital due to non-cardiopulmonary disorders (Group 2). In both groups, Rint values were inversely associated with age, weight and height, but the strongest association was with height. The linear regression equation for Group 1 (n = 209, height 86-129 cm) was Rint = 2.153 - 0.012 × height (cm) (standard deviation of residuals 0.181 kPa/L/s). The linear regression equation for Group 2 (n = 55, height 52-113 cm) was Rint = 4.575 - 0.035 × height (cm) (standard deviation of residuals 0.567 kPa/L/s). Girls tended to have slightly higher Rint values than boys, a difference that diminished with increasing height. In this study, Rint reference values applicable to Mexican children were determined, and these values are probably also applicable to other paediatric populations with similar Spanish-Amerindian ancestries. There was an inverse relationship between Rint and height, with relatively large between-subject variability.

Measurement and repeatability of interrupter resistance in unsedated newborn infants

Interrupter resistance (R(int)) is a useful measure of airway caliber in young children, but has not been well characterized in infants-in whom there are concerns about the accurate measurement of driving pressure. This study aimed to assess the feasibility and repeatability of measuring R(int) in unsedated newborn infants, and to explore alternative algorithms for calculating driving pressure. R(int) measurement was attempted in 28 healthy term newborn infants during natural sleep using the MicroRint device. Paired R(int) measurements were achieved in 24 infants, but after screening of waveforms only 15 infants had at least 5 technically acceptable waveforms on both measurements. R(int) values obtained were comparable with reported values for airflow resistance in newborns using other methods. However, the repeatability coefficient (CR) was much higher than reported values in preschool children using standard back-extrapolation algorithms, with CR 2.47 KPa L(-1) sec (unscreened) and 2.93 KPa L(-1) sec (screened). Other algorithms gave only marginally better repeatability, with all CR values over 50% of the mean R(int) value. Using current commercially available equipment, R(int) is too poorly repeatable to be a reliable measurement of airflow resistance in newborn infants. Lower deadspace equipment is needed, but anatomical and physiological factors in the infant are also important.

Interrupter Respiratory Resistance in Healthy Chinese Preschool Children

Interrupter respiratory resistance (Rint) is useful in evaluating lung function in children who cannot perform the traditional lung function tests. However, available reference Rint values are confined to whites. Our aims were as follows: (1) to establish reference values in local preschool Chinese children, (2) to examine their relationship with demographic and anthropometric factors, and (3) to determine the 10-min and 6-week repeatability of Rint. Rint was measured in preschool children from randomly chosen local kindergartens, and the repeatability of Rint measurement was assessed in a subgroup of subjects 10 min and 6 weeks after the initial measurement. Rint measurement was performed in 509 children between 4 and 6 years of age. Age, height, and weight significantly inversely correlated with Rint values. However, on multiple linear regression, height was the only variable that independently correlated with Rint. Repeat measurements obtained 10 min and 6 weeks after the initial reading in 45 children showed good agreement with little variability, and the interclass correlation coefficients for 10-min and 6-week measurements were 0.877 and 0.923, respectively. Rint reference centile curves for Chinese preschool children have been determined. Rint in preschool Chinese children has good short- and long-term repeatability.

Lung function measurement in prematurely born preschool children with and without chronic lung disease

Prematurely born infants often have recurrent wheeze and long-term respiratory morbidity at follow-up. Assessment of airways obstruction in preschool children is feasible using the interrupter resistance (Rint) but has rarely been examined in preterm children with and without chronic lung disease (CLD). The objective of this study was to determine lung function measured by the interrupter technique, its feasibility in the ambulatory setting and respiratory health in prematurely born preschool children with and without CLD. Preterm children of 2 to 4 years with severe CLD (>30% oxygen at 36 weeks and discharged home receiving supplemental oxygen) (n=43, median gestational age 27 weeks and median birth weight 995 g) and without CLD (n=33, median gestational age 29 weeks and median birth weight 1366 g) attempting lung function test for the first time were enrolled. Respiratory symptoms score was calculated using a questionnaire. A single set of 10 consecutive Rint measurements was obtained using a portable device (MicroRint). Median of at least five occlusions with consistent shape of mouth pressure-time curves was taken to be a Rint measurement. To assess feasibility the children were categorized as 'satisfactory', 'failure' and 'rejected' depending on the outcome of the test. Outcome variables were respiratory symptoms score and Rint. Satisfactory Rint measurement was obtained in 46 (61%) children, 9 (36%) 2-year olds, 17 (65%) 3-year olds and 20 (80%) 4-year olds. As compared with the preterm control children (n=18), CLD children (n=28) had significantly higher respiratory symptoms score (18.5 vs 6, P<0.01) and Rint expressed as absolute values (kPa l(-1)) and z-scores (1.33 vs 1.16 and 1.42 vs 1.0, P<0.01), respectively. Rint measurement is feasible in prematurely born children of preschool age in the ambulatory setup. Preschool children with severe CLD may be identified from preterm children without CLD by increased Rint that may be used as a screening tool and as an outcome measure for interventions.

The interrupter technique to assess airway responsiveness in children with cystic fibrosis

The aim of this study was to assess the validity of the interrupter technique (Rint) in measuring airway responsiveness in children with cystic fibrosis. Fifty children (aged 6-16 years) with cystic fibrosis performed six Rint measurements followed by three acceptable forced expiratory maneuvers. Each child then inhaled 5 mg of nebulized salbutamol by facemask. After 20 min the Rint and forced expiratory measurements were repeated. In the population as a whole a moderate but significant correlation between inverse Rint and FEV1 values was observed, both before and after inhaled bronchodilator (r=0.71 and 0.72, respectively, P < 0.001). However, when changes in Rint and FEV1 readings following inhaled bronchodilator were examined, no relationship was seen. Indeed, the two methods identified completely different subsets of children as being bronchodilator responsive. These results indicate that although a relationship exists between Rint and FEV1 in the whole population, this is not the case in individual children. Rint and FEV1 reflect different aspects of lung function. It is not appropriate to use Rint as a simple alternative for FEV1 in children with cystic fibrosis when assessing airway responsiveness.

Applicability of interrupter resistance measurements for evaluation of exercise‐induced bronchoconstriction in children

The interrupter technique is a noninvasive method for measuring air-flow resistance during tidal breathing. This method requires minimal cooperation, and is therefore promising for use in uncooperative children. The aim of this study was to evaluate applicability interrupter resistance (Rint) measurements in the assessment of exercise-induced bronchoconstriction (EIB). Fifty children aged 5-12 years with mild to moderate asthma were tested by exercise challenge, consisting of free outdoor running for 6 min at 80-90% of maximal predicted heart rate for age. Rint, forced expiratory volume in 1 sec (FEV1), and peak expiratory flow (PEF) were measured before and 10 min after exercise. EIB was defined as a fall of 10% or more in FEV1 after exercise. The repeatability of Rint was assessed, and its response to exercise challenge was compared with current standardized methods. The mean intermeasurement coefficient of variation was 4.6% (SD, +/- 3.0%), and the repeatability coefficient was 0.056 kPa/l/sec. Eighteen (36%) of the 50 children had EIB after exercise challenge test. The area under the receiver-operating characteristic (ROC) curve was 0.953 (95% confidence interval, 0.853-0.992; P < 0.001), and the optimal Rint cutoff value was 15.2%, producing a sensitivity of 88.9% and a specificity of 96.9%. The positive and negative predictive values were 94.1% and 93.9%, respectively. The kappa value between FEV1 and Rint was 0.83. The repeatability of Rint measurements was good, and the results of exercise challenge tests using Rint measurements have excellent agreement with the current standardized methods to detect EIB. Considering that only minimal comprehension and coordination are needed without forced breathing technique, the Rint measurement can provide a useful alternative for assessment of EIB in children unable to perform reliable spirometry.

Plethysmograph and interrupter resistance measurements in prematurely born young children

Background: Airways obstruction in premature infants is often assessed by plethysmography, which requires sedation. The interrupter (Rint) technique does not require sedation, but has rarely been examined in children under...

Pressure Oscillation Amplitude after Interruption of Tidal Breathing as an Index of Change in Airway Mechanics in Preschool Children

Bronchodilator reversibility testing using change in airway resistance during interruption (Rint) is feasible in preschool children. Analysis of postocclusion oscillations of the mouth pressure-time transient (Pmo(t)), recorded during airflow interruption, may offer an alternative index of change in airway mechanics. We analyzed Pmo(t) oscillation amplitude in three different ways: 1) difference between the first relative maximum and minimum (AMxMn); 2) detection of the dominant frequency using Fourier analysis (AFS); and 3) curve-fitting based on a mathematical model (ACurv). In 25 asymptomatic asthmatic children, aged 2.5-5.6 years, who had undertaken reversibility testing, the correlation coefficients between baseline Rint and amplitude were: AMxMn r = -0.84, AFS r = -0.82, ACurv r = -0.84. The coefficient of variation (CoV) of readings contributing to baseline Rint measurement, as median (range), was 12% (5-24%), which was not significantly different from AFS or ACurv (P > 0.05). All parameters were significantly different postbronchodilator (P < 0.001). Using the sensitivity index, i.e., the change after intervention divided by the baseline standard deviation, ACurv was the most sensitive and Rint the least sensitive, with median (range) at 2.72 (-0.84 to 12.10) and 1.91 (-1.17 to 9.50), respectively (P = 0.005). Our results suggest that oscillation amplitude analysis may provide a sensitive index of change in airway mechanics in preschool children undertaking bronchodilator reversibility testing.

Airway Resistance Measurements in Children with Cystic Fibrosis

Summary Background and Purpose Respiratory function test results are important indices of improvement in the treatment of respiratory infection in cystic fibrosis. The aim of this study was to assess the value of airways resistance measured by the interrupter technique (Rint) over a course of intravenous antibiotic treatment in children with cystic fibrosis. Methods Airways resistance was measured by the MicroRint at the beginning and end of treatment. Children aged five years and older also had respiratory function measured, using standard spirometry. Results Seventy-eight children were entered into the study. Children under two years of age were not able to achieve a satisfactory facemask seal. Six children under seven years of age could not provide satisfactory spirometric measurements but showed an improvement in Rint measurement. All respiratory function parameters improved significantly. Before and after treatment airways resistance values measured by the MicroRint showed a significant correlation with respiratory function test values measured by standard spirometry, eg for Rint and FEV 1 % predicted normal r=0.37 before treatment (p = 0.002), and r=0.39 after treatment (p = 0.002). Similar results were obtained for comparisons between Rint and FEF 25–75 % predicted normal values. The degree of change in the airways resistance values measured by the MicroRint when measurements at the beginning and end of treatment were compared did not show a significant correlation with the degree of change in spirometric values measured at the same times. Conclusions Children over two years of age tolerate Rint measurement well. In cystic fibrosis, over a course of intravenous antibiotic therapy, it may be a valuable additional measure of the response to treatment.

Pulmonary function tests in preschool children with cystic fibrosis.

Pulmonary function tests have rarely been assessed in preschool children with cystic fibrosis (CF). The objective of this multicenter study was to compare pulmonary function in 39 preschool children with CF (height, 90-130 cm; 16 homozygous Delta F508) and in 79 healthy control children. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (Rint(exp)) (interrupter technique) were measured. As compared with control children, children with CF had significantly higher Rint(exp), expressed as absolute values and as Z-scores (1.05 +/- 0.36 versus 0.80 +/- 0.20 kPa.L(-1). second, p < 0.0001; and 1.31 +/- 1.72 versus 0.19 +/- 0.97, p < 0.0001), and significantly lower specific expiratory interrupter conductance (1.29 +/- 0.34 versus 1.63 +/- 0.43 kPa(-1). second, p < 0.0001). The effect of the bronchodilator salbutamol on Rint(exp) was not significantly different between children with CF and control children. Rint(exp) Z-scores were significantly higher in children with CF who were exposed to passive smoke (n = 8) (p < 0.03). Children with CF and with a history of respiratory symptoms (n = 31) had significantly higher functional residual capacity Z-scores (p < 0.02) and lower specific expiratory interrupter conductance Z-scores (p < 0.04). Genotype did not influence the data. We conclude that Rint(exp) and functional residual capacity measurements may help to follow young children with CF who are unable to perform reproducible forced expiratory maneuvers.

Reference values of interrupter respiratory resistance in healthy preschool white children

BACKGROUNDInterrupter respiratory resistance (Rint) is reported to be useful in evaluating lung function in poorly collaborating patients. However, no reference values are available from large samples of preschool children using the standard interrupter method. The aim of this study was to define reference Rint values in a population of healthy preschool children.METHODSRint was assessed without supporting the cheeks in children with no history of wheeze from six kindergartens. To evaluate the effects of upper airway compliance on Rint in healthy children, an additional group of preschool children with either no history of wheeze or no respiratory symptoms at the time of testing underwent Rint measurements in our lung function laboratory with and without supporting the cheeks. Short term (about 1 minute apart) and long term (mean 2.5 months apart) repeatability of Rint measurements (2 SDs of the mean paired difference between measurements) was also assessed in children referred for cough or wheeze.RESULTSA total of 284 healthy white children (age range 3.0–6.4 years) were evaluated. Mean inspiratory and expiratory Rint (Rintiand Rinte) did not differ significantly in boys and girls. Age, height, and weight showed a significant inverse correlation with both Rintiand Rintein the univariate analysis with linear regression. Multiple regression with age, height, and weight as the independent variables showed that all three variables were significantly and independently correlated with Rinti, whereas only height was significantly and independently correlated with Rinte. Supporting the cheeks had no significant effect on Rinti(n=29, median 0.673v0.660 kPa/l.s, p=0.098) or Rinte(n=39, median 0.702v0.713 kPa/l.s, p=0.126). Short term repeatability was 0.202 kPa/l.s for Rinti(n=50) and 0.242 kPa/l.s for Rinte(n=69). Long term repeatability was 0.208 kPa/l.s for Rinte(n=26).CONCLUSIONSWe have reported reference Rint values in preschool white children and have demonstrated the usefulness of this technique in assessing lung function in this age group.

Reference values of interrupter respiratory resistance in healthy preschool white children

BACKGROUNDInterrupter respiratory resistance (Rint) is reported to be useful in evaluating lung function in poorly collaborating patients. However, no reference values are available from large samples of preschool children using...

Lung function and short-term outcome in young asthmatic children.

The aims of this study were to investigate lung function in 2-5-yr-old stable asthmatic children consecutively referred from general practitioners and to analyse the outcome on the basis of their requirement for antiasthmatic treatment and symptoms after 1.6-4.5 yrs. Lung function was measured in 110 children with a mean+/-SD age of 3.8+/-1.0 yrs using the interruptor technique (resistance assessed using the interruptor technique (Rint)), whole body plethysmography (specific airway resistance (sRaw) and respiratory resistance (Rrs,5)and reactance at 5 Hz (Xrs,5) using the impulse oscillation technique. Rint, sRaw, Xrs,5 and Rrs,5 were suggestive of impaired lung function in 44%, 14%, 11% and 7.5% of the children, respectively, with a predominance of children aged 2-3 yrs. Sixty-five per cent were treated with inhaled steroids, and 35% were treated only with beta2-agonists as needed; lung function was not significantly different between these two groups. Outcome after 2.9+/-0.7 yrs was not significantly different between children with Rint measurements above and those children with Rint measurements within the reference range at enrolment. Of these children, 58 and 59% were currently on antiasthmatic treatment, and 40% and 49% had current symptoms, respectively. Impairment of lung function may be a common finding in stable young asthmatic children, but apparently this is not a risk factor for persistence of asthmatic symptoms.