Objective: To study upper airway breathing in 115 children annually from 8 to 17 years of age with the hypothesis that upper airway respiratory needs increase steadily during growth and show sexual dimorphism. Material and Methods: To calculate nasal resistance, airflow rate (mL/s) and oronasal pressures (cmH 2 O) were measured during rest breathing in a seated position using the pressure-flow technique.Results: Median values of oronasal pressure ranged at different ages in girls from 0.88 to 1.13 and in boys from 0.92 to 1.44 cmH 2 O, being 0.95 and 0.93 cmH 2 O at the age of 17 years, respectively. The gender differences were statistically significant in four age groups (P , .05 by the Mann-Whitney test). Mean values of nasal resistance decreased from 8 to 17 years of age in girls from 4.0 (63.27) to 2.4 (62.30) and in boys from 3.3 (62.48) to 1.5 (60.81) cmH 2 O/L/s. However, there was an increase in resistance in 11-year-old girls and 12-year-old boys and at the age of 15 in both genders (P , .05 by paired t-test). Conclusions: Respiratory efforts stabilize oronasal pressure to maintain vital functions at optimal level. Nasal resistance decreased with age but increased temporarily at the prepubertal and pubertal phases, in accordance with other growth and possibly hormonal changes. When measuring upper airway function for clinical purposes, especially in patients with sleep apnea, asthma, allergies, cleft palate, or maxillary expansion, the measurements need to be compared with age-and genderspecific values obtained from healthy children. (Angle Orthod. 2016;86:610-616.)

Our results indicate that the increase in nasal airway size is not consistent during growth. Nasal airway size showed almost equal values for both genders in young children but was systematically larger in boys from 14 years of age on. The results refer that by 17 years of age nasal airway may not have reached adult size in males.

ObjectivesTo assess breathing behaviors and perception of added respiratory loads in young compared to old individuals, and to determine whether aging affects the perception and response to changes in nasal airway resistance.Study designIn a clinical study, 40 young (11–20 years) and 40 older (59–82 years) subjects were evaluated during rest breathing and during the application of added airway resistance loads.MethodsThe pressure‐flow technique was used to measure airflow rate (mL/s) and oral‐nasal pressures (cmH2O) to calculate nasal resistance (cmH2O/L/s). To create calibrated resistance loads for the test conditions, we used a device modified from a precision iris diaphragm.ResultsDuring rest breathing airflow rate was significantly lower for the younger group compared to older group. Using the loading device, 11–20‐year‐olds detected increased resistance at the level of 2.26 cmH2O/L/s compared to 4.55 cmH2O/L/s in 59–82‐year‐olds. In contrast to the younger group, mean airflow rate was higher during expiration than during inspiration among 59–82‐year‐olds except at rest breathing.ConclusionsThe data revealed that the perception and respiratory response to increased airway resistance changed with aging. Younger subjects were more sensitive to changes within the airway. In both groups, subjects responded to increased airway resistance by decreasing airflow rate. However, expiratory phase became more active than inspiratory phase only in the older group.Level of EvidenceN/A