Reference ranges for respiratory rate measured by thermistry (12-84 months).

Abstract

Previous studies of respiratory rate in children have had a number of methodological problems. The aim of this study was to construct age specific reference ranges for respiratory rate. Respiratory rate in children attending childcare centres, kindergartens, and schools was measured using a nasal thermocouple to obtain respiratory waveforms. Reference ranges were constructed using data from 293 awake children between 12 and 84 months, and from 123 sleeping children between 12 and 60 months. performed on some of the children and there was no record of whether respiratory symptoms or signs were present. The method of determining rate is not recorded, although it was probably based on the counting of chest wall movements. Children of different ages were measured in different arousal states. The heterogeneity of these subjects' arousal states raises doubts about the validity of the results. It is widely accepted that ventilatory control and respiratory rate are altered in both rapid eye movement and non-rapid eye movement sleep when compared with the awake state.5 6 The utility of the quoted reference ranges remains in doubt because of these methodological problems.Respiratory rate is traditionally measured by counting observed chest wall movements while timing with a watch. While this method is simple, and should not alter the variable being measured, its accuracy is questionable. A study comparing the counting of observed chest wall movements by nurses to respiratory inductive plethysmography in 10 mechanically ventilated adult patients found that on 34% of occasions manual counting of respiratory rate produced an error of 20% or more.7 Another study comparing simultaneous respiratory rate counts, as determined by observation of chest wall movement and by transthoracic impedance (pneumogram), in children under 5 years of age found a wide variation between these two methods.8 The method that produced a respiratory rate per minute that varied least from that obtained with the pneumogram, was where the counted respiratory rates for two 30 second periods were added, rather than using a single 60 second period or a single 30 second period doubled.

Breathing Frequency Changes at the Onset of Stepping in Human Infants

“…It was, however, useful for the studies to determine the effects of a soother done in a sitting. The thermocouple method has been used in the past for children Ն12 mo of age (Marks et al 1993). In that study, the thermistor was taped to the face near the naris.…”

“…The thermocouple was custom made from thermocouple alloy wire (YSI Temperature, Dayton, OH). Thermocouples of this sort have been used successfully to measure the rate of breathing in adults (Marks et al 1995) and children (Marks et al 1993). The wire was taped to the top portion of an infant's soother so that the thermocouple was directly below the right naris.…”

Analysis of respiratory rate and the respiratory cycle in infants and children using an optical sensor

“…No medical examination was done on the children, since this would have increased their anxiety (Marks, South and Carlin, 1993). However, noisy breathing and rhinorthoea were readUy observed.…”

“…Table 3.4 summarises the general findings of breathing pattems in tiie two main sleep states (Hathom, 1974;Stefanski et al, 1984). Because infants were easUy upset, only a smaU number were tested when the> were awake Scoring of sleep state based on behavioural criteria was Umited vwthout an electroencephalogram (EEG), electrooculogram and electromyogram (Marks, South and Carlin, 1993). Another way of describing the sleep pattems is that of regular and non-regular breathing pattems.…”

“…The questions were similar to those of Marks, South and Carlin (1993) and included sore throat, breathlessness. 45 cough, fever, "runny nose" and night cough.…”