Determinants of tidal flow volume loop indices in neonates and children with and without asthma

Abstract

The tidal flow volume (TFV) loop ratios of (1) time to peak flow (tPTEF) to total expiratory time (tE) [tPTEF/tE] and (2) volume to peak flow (VPTEF) to expired volume (VE) [VPTEF/VE] are reported to decrease with age in early life, and to decrease in subjects with obstructive airways disease (OAD). However, the mechanisms behind these changes are not well known. Thus, we reanalyzed data from 24 healthy neonates (mean birthweight: 3.49 kg ± 0.42 kg (SD)), 26 presently asymptomatic asthmatic children (age: 33 ± 21 months), and 26 controls (age: 34 ± 19 months) to elucidate what is responsible for the changes in these ratios in health and disease. Lung function was measured by TFV loops (SensorMedics 2600) at 1 hour of life and on the following day in the neonates, and before and after inhaled nebulized salbutamol (0.05 mg/kg) in the asthmatics and their controls. The observed decreases in mean tPTEF/tE and VPTEF/VE from 1 hour to 1 day of life (neonates) were entirely due to increased tE and VE, respectively secondary to a decrease in respiratory rate (P = 0.03). In asthmatics (young children), the decreased baseline tPTEF/tE and VPTEF/VE were due to lower tPTEF and VPTEF, with no significant differences in tEe and VE in asthmatics and controls. The improved ratios in asthmatic children following inhalation of a bronchodilator were mainly due to increased tPTEF and VPTEF. Our observations point out the importance of evaluating both tPTEF and either tPTEF/tE or VPTEF/VE when attempting to differentiate between changes in ratios that are related to age versus changes that reflect underlying obstructive airways disease. Pediatr. Pulmonol. 1997; 24:391–396. © 1997 Wiley‐Liss, Inc.

Electromagnetic inductance plethysmography to measure tidal breathing in preterm and term infants

“…Both values for preterm and term infants reported by Latzin et al22 were lower than in our study, but their infants were chronologically much older. Our results were comparable to those from other studies 19–21…”

“…It has previously been shown that the flow parameter t PTEF /t E is dependent on the postnatal age. The t PTEF /t E decreases during the first week of life from 45% at birth to 32% at 5 days19, 20 and then further during first 2 months of life 21. In the current study, the preterm infants were significantly older chronologically than the term infants at the time of the study (Table 1).…”

Tidal breath in healthy term newborns: An analysis from the 2nd to the 30th days of life

“…The reference values for VPTEF/VE, TEF75, TEF50, and TEF25 in healthy neonates are very limited. The decrease observed in VPTEF/VE during the neonatal period was in agreement with the results of previous studies 23,32 . Lodrup Carlsen et al 23 reported a mean VPTEF/VE value of 0.40 for male and 0.37 for female neonates at 2 days of age.…”

Epidemiology and associations with climatic conditions of Mycoplasma pneumoniae and Chlamydophila pneumoniae infections among Chinese children hospitalized with acute respiratory infections

“…Tidal breathing measurements included flow and volume signals, and were assessed by professional staff. Lung function was graded as normal, mild, moderate, severe, or extremely severe according to three-component score system which could reflect underlying obstructive airways disease [14,15] as shown in Table 1.…”