Respiratory impedance and response to salbutamol in healthy Vietnamese children

Abstract

A high incidence of childhood asthma has been reported in Ha Noi, Viet Nam, indicating a need to document lung function in these children. The degree of airway obstruction and reversibility may be evaluated from the forced oscillation assessment of respiratory resistance to reactance (Rrs, Xrs). Appropriate controls are necessary for a proper interpretation of patients. The aim of the study was to provide reference values on Rrs and Xrs and response to salbutamol in healthy Vietnamese children. One hundred seventy-five children aged 6-11 year recruited from one public school in Ha Noi were studied. Measurements were obtained at baseline and after 200 microg inhaled salbutamol. Significant correlations were disclosed between Rrs or Xrs and standing height (P < 0.0001). Salbutamol significantly decreased Rrs (from 7.1 +/- 1.9 hPa.sec/L to 6.2 +/- 1.8 hPa sec/L, P < 0.0001) and increased Xrs (from -1.22 +/- 0.64 to -0.91 +/- 0.61 hPa.sec/L, P < 0.0001). Rrs response to salbutamol lower limit of 95% confidence interval was -38% from baseline Rrs and, Xrs upper limit was +16% from baseline impedance. It is concluded that reference values for respiratory impedance (Zrs) and thresholds for clinically relevant response to bronchodilator are provided in primary school Vietnamese children. A smaller slope for the observed Rrs-body height relationship is suggested with reference to relevant studies in healthy Caucasians.

Respiratory impedance and response to salbutamol in asthmatic Vietnamese children

“…The FOT setup has been described previously. 17 The characteristics of pressure transducers, flowmeter, electronics, electrical supply, and signal analysis were similar to the Pulmosfor (SEFAM, Vandoeuvre, France), which is in conformity with current recommendations. 2,3 The pressure transducer was calibrated using a slanted water manometer that accurately provided a pressure step ranging 1-2 hPa, and the flowmeter by the integral method using a 1-L syringe.…”

“…The custom-made equipment was adapted from-and tested against a long validated apparatus 22 -offered little extra cost, facilitated Pediatric Pulmonology Respiratory Impedance in Asthmatic Children adaptation to local requirements as well as numerical file exchanges between laboratories, and provided easy maintenance and supply. 17 The set up somewhat differs from most prior studies where multi-frequency excitation signals have usually been applied. 2 The frequency of 8 Hz is within the range where most clinically significant results have been reported, 2 and a single sine wave was thought to have the further advantage of optimizing the signal-tonoise ratio.…”

“…Inclusion criteria were no history of recurrent wheezing, exercise induced cough, dyspnea, or wheezing, no prior medical diagnostic of asthma and lack of respiratory tract infection at the time of the study. 17 The study was approved by a board comprising representatives of the doctors and administrators from Saint Paul Hospital. Informed consent was obtained from the children and their parents.…”

Respiratory function in healthy Emirati children using forced oscillations

“…Regional studies on the use of FOT to monitor and manage respiratory diseases are necessary . Currently, FOT reference equations are available for Caucasians and non‐Caucasians . However, studies in children from the Arabian Peninsula are lacking.…”

Small airway bronchodilator response to different doses of salbutamol in 7-year-old children

“…In fact, epidemiological studies accept standard BDR reference values based on oscillometric BDR data from low-dose salbutamol in healthy volunteers [ 9 – 13 ]. However, previous researchers have used different criteria to define “healthy control” such as the following: no history of asthma, cystic fibrosis, neonatal chronic lung disease, or respiratory infection in the 2 weeks prior to study onset (Thamrin et al criteria) [ 10 , 11 ]; and the Thamrin et al criteria in addition to no preterm and low birth weight infants (>36 weeks gestational age and >2.5 kg of birth weight) who had not received oxygen at birth [ 12 , 13 ]; in addition to no exposure to second-hand smoke and normal body mass index such as criteria of the American Thoracic Society [ 14 ]. We used a more stringent set of criteria for healthy children than the criteria of the American Thoracic Society because we added an additional criteria of FEV 1 [ 14 ].…”