Nasal nitric oxide measurement in children for the diagnosis of primary ciliary dyskinesia: European Respiratory Society technical standard.

Nasal nitric oxide (nNO) is extremely low in most people with primary ciliary dyskinesia (PCD) and its measurement is an important contributor to making the diagnosis. Existing guidelines and technical standards focus on nNO measurements in older, cooperative children using chemiluminescence analysers. However, measurements of nNO in pre-school-age children (age 2-5 years) may facilitate early diagnosis and electrochemical rather than chemiluminescence analysers are widely used. Pre-schoolers often need different methods to be employed when measuring nNO. Hence, a European Respiratory Society Task Force has developed this technical standard as the first step towards standardising sampling, analysis and reporting of nNO measured as part of the diagnostic testing for PCD in all age groups, including pre-school-age children. Furthermore, we considered both chemiluminescence and electrochemical analysers that are in use worldwide. There was a paucity of quality evidence for electrochemical analysers and sampling methods used in young children, and the Task Force proposes future research priorities to allow updates of this technical standard.

An international survey on nasal nitric oxide measurement practices for the diagnosis of primary ciliary dyskinesia.

Nasal nitric oxide (nNO) measurements are used in the assessment of patients suspected of having primary ciliary dyskinesia (PCD), but recommendations for performing such measurements have not focused on children and do not include all current practices. To guide the development of a European Respiratory Society-supported technical standard for nNO measurement in children, an international online survey was conducted to better understand current measurement practices among providers involved in PCD diagnostics. 78 professionals responded, representing 65 centres across 18 countries, mainly in Europe and North America. Nearly all centres measured nNO in children and more than half performed measurements before 5 years of age. The test was often postponed in children with signs of acute airway infection. In Europe, the electrochemical technique was more frequently used than chemiluminescence. A similar proportion of centres performed measurements during exhalation against a resistance (49 out of 65) or during tidal breathing (50 out of 65); 15 centres used only exhalation against a resistance and 15 used only tidal breathing. The cut-off values used to discriminate PCD were consistent across centres using chemiluminescence analysers; these centres reported results as an output (nL·min-1). Cut-off values were highly variable across centres using electrochemical devices, and nNO concentrations were typically reported as ppb. This survey is the first to determine real-world use of nNO measurements globally and revealed remarkable variability in methodology, equipment and interpretation. These findings will help standardise methods and training.

Dietary Nitrate Acutely and Markedly Increased Exhaled Nitric Oxide in a Cystic Fibrosis Case.

Airway nitric oxide (NO) is a ubiquitous signaling molecule with bronchoprotective, anti-inflammatory and anti-infective roles. Cystic fibrosis (CF) is a chronic lung condition associated with deceased exhaled NO. Strategies to increase exhaled NO in CF have yielded inconsistent results. A potential new method of increasing systemic NO involves ingestion of dietary, inorganic nitrate which is reduced to nitrite and NO. We present the case of a 12-year-old, athletic boy with CF who demonstrated acute but marked increases in exhaled NO following dietary nitrate consumption compared to placebo.

Do gender differences exist in the ventilatory response to progressive exercise in males and females of average fitness?

Gender differences in lung volumes and flow rates, and in respiratory control have been documented previously. How these gender differences affect exercise responses in normal subjects is less clear, particularly as many studies involved highly fit subjects. This study aimed to investigate potential gender differences occurring during progressive exercise in healthy males and females of average fitness. Fourteen males and ten females of mean (SD) age 23 (0.35) years completed a progressive exercise test to exhaustion on a cycle ergometer, with a ramp increase of 15 W min(-1) (female) or 20 W min(-1) (male). All females were studied during the follicular phase of their menstrual cycle. Cardiorespiratory variables were measured, breath by breath, and values were compared at rest, at 40 W, at physiologically equivalent workloads below, at and above the gas exchange threshold and at peak oxygen uptake (VO(2peak)). Mean VO(2peak) (SEM) was 32.4 (2.01) ml kg(-1) min(-1) for the females and 41.9 (1.80) ml kg(-1) min(-1) for the males. Females had a significantly lower end-tidal partial CO(2) pressure at rest and throughout exercise. Increases in exercise minute ventilation were achieved by a significantly greater tidal volume in males, whereas females adopted a significantly greater breathing frequency. Ratings of respiratory discomfort were significantly greater in the male group at physiologically equivalent workloads compared to the female group. This study shows gender differences exist in the ventilatory and sensory response to progressive exercise in untrained subjects. Further work is required to ascertain if these effects are altered during the luteal phase of the menstrual cycle.