Bronchodilator response cut-off points and FEV 0.75 reference values for spirometry in preschoolers

ABSTRACT Objective: To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75. Methods: This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter. Results: We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively. Conclusions: Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children

Noninvasive assessment of asthma severity using pulse oximeter plethysmograph estimate of pulsus paradoxus physiology

<p>Abstract</p> <p>Background</p> <p>Pulsus paradoxus estimated by dynamic change in area under the oximeter plethysmograph waveform (PEP) might provide a measure of acute asthma severity. Our primary objective was to determine how well PEP correlates with forced expiratory volume in 1-second (%FEV₁) (criterion validity) and change of %FEV₁(responsiveness) during treatment in pediatric patients with acute asthma exacerbations.</p> <p>Methods</p> <p>We prospectively studied subjects 5 to 17 years of age with asthma exacerbations. PEP, %FEV₁, airway resistance and accessory muscle use were recorded at baseline and at 2 and 4 hours after initiation of corticosteroid and bronchodilator treatments. Statistical associations were tested with Pearson or Spearman rank correlations, logistic regression using generalized estimating equations, or Wilcoxon rank sum tests.</p> <p>Results</p> <p>We studied 219 subjects (median age 9 years; male 62%; African-American 56%). Correlation of PEP with %FEV₁demonstrated criterion validity (r = - 0.44, 95% confidence interval [CI], - 0.56 to - 0.30) and responsiveness at 2 hours (r = - 0.31, 95% CI, - 0.50 to - 0.09) and 4 hours (r = - 0.38, 95% CI, - 0.62 to - 0.07). PEP also correlated with airway resistance at baseline (r = 0.28 for ages 5 to 10; r = 0.45 for ages 10 to 17), but not with change over time. PEP was associated with accessory muscle use (OR 1.16, 95% CI, 1.11 to 1.21, P < 0.0001).</p> <p>Conclusions</p> <p>PEP demonstrates criterion validity and responsiveness in correlations with %FEV₁. PEP correlates with airway resistance at baseline and is associated with accessory muscle use at baseline and at 2 and 4 hours after initiation of treatment. Incorporation of this technology into contemporary pulse oximeters may provide clinicians improved parameters with which to make clinical assessments of asthma severity and response to treatment, particularly in patients who cannot perform spirometry because of young age or severity of illness. It might also allow for earlier recognition and improved management of other disorders leading to elevated pulsus paradoxus.</p

Nonimmune rosette formation: a measure of the newborn infant's cellular immune response.

Nonimmune rosette formation, an in vitro measure of cellular immunity, was evaluated in normal newborn infants. Active rosette formation in 14 specimens of cord blood was 18.9 +/- 4.8% compared to 28.1 +/- 5.2% in 15 adult control samples (p less than 0.05). Total rosette formation in 13 cord blood samples was 33.3 +/- 7.6% compared to 55.1 +/- 6.5% in 15 adult control specimens (p less than 0.05). Tritiated thymidine uptake from phytohemagglutinin stimulation was comparable in cord blood and adult control lymphocytes. The importance of these findings is discussed in light of other recent reports suggesting that cord blood thymic derived T lymphocytes may have reduced immune capability when compared to adult lymphocytes

Capillary pH and blood gas determinations in asthmatic children.

Earlobe capillary pH and blood gases in asthmatic children were compared to arterial values. Hyperemia of the earlobe was produced by applying thurfyl nicotinate (Trafuril). Approximately 15 min later capillary blood was obtained simultaneously with a radial arterial sample. Earlobe capillary PO2, PO2, and pH correlated well with arterial values. This technique is simple, safe, and appears to be a satisfactory substitute for arterial blood in normotensive asthmatic children

Capillary pH and blood gas determinations in asthmatic children.

Earlobe capillary pH and blood gases in asthmatic children were compared to arterial values. Hyperemia of the earlobe was produced by applying thurfyl nicotinate (Trafuril). Approximately 15 min later capillary blood was obtained simultaneously with a radial arterial sample. Earlobe capillary PO2, PO2, and pH correlated well with arterial values. This technique is simple, safe, and appears to be a satisfactory substitute for arterial blood in normotensive asthmatic children

Relationship between cutaneous delayed hypersensitivity and cell-mediated immunity in vitro responses assessed by diphtheria and tetanus toxoids.

Cutaneous delayed hypersensitivity (CDH) testing with microbial antigens in man is thought to reflect the status of cell-mediated immunity (CMI). We have evaluated diphtheria-tetanus (DT) and tetanus (T) toxoids by comparing the CDH response with in vitro parameters of CMI: lymphocyte deoxyribonucleic acid (DNA) synthesis, leukocyte inhibition factor (LIF) in 5 immunized adults, and lymphotoxin release in 2 adults. Cord blood lymphocytes were used as controls for each assay. A dose response with both toxoids was used to compare the CDH reaction with each in vitro assay, establishing the maximum response and threshold dose which gave a positive response. All subjects had a positive CDH response to both antigens (≥5 mm induration at 48 hr), positive DNA synthesis (stimulation index ≥3), LIF release (migration ≤80%), and lymphotoxin production, while cord blood lymphocytes were usually negative to all in vitro assays. No consistent quantitative relationships between CDH reactions and in vitro CMI responses were seen. Threshold antigen dose data revealed that DNA synthesis was approximately ten times as sensitive an assay as CDH, and 105 times as sensitive as the LIF technique. No difference in sensitivity was noted between DT and T toxoids. Three subjects re-evaluated 16 mo after the initial study showed positive CDH and CMI responses to tetanus toxoid, although the antigen dosage required varied considerably. We conclude that the CDH response with either toxoid in the concentrations used is a good indicator of CMI in the immunized individual. Although recommended starting antigen dose is given for each assay, a dose response for each assay must be performed to adequately evaluate the CMI responsiveness to a test antigen. © 1977