Related Experiment Video
Updated: May 20, 2026
A Novel Inhalation Mask System to Deliver High Concentrations of Nitric Oxide Gas in Spontaneously Breathing Subjects
Published on: May 4, 2021
Setting reference values for exhaled nitric oxide: a systematic review
Tiago Jacinto1, Kjell Alving, Ricardo Correia
1CINTESIS – Center for Research in Health Technologies and Information Systems, Faculty of Medicine, University of Porto, Porto, Portugal. tiagojacinto@med.up.pt
Background:
The values obtained when the fraction of exhaled nitric oxide (FeNO) is measured are affected by several factors that are specific to the individual patient, making interpretation difficult, especially in the initial assessment of patients with respiratory symptoms.
Methods:
Systematic review of studies on FeNO reference values and individual-specific factors that influence them.
Results:
From 3739 references, 15 studies were included. Four studies included children and adolescents. In nine studies, samples were selected from the general population. Most studies reported objective measures for atopy (nine studies), but not for smoking status (one). Significant determinants of FeNO values reported were age and height (seven studies), atopy (six), smoking (four), weight (four), sex (three) and race (three). Additional factors were included in eight studies. R2 was reported in only five studies. The logarithmic transformation of FeNO was inadequately described in seven studies.
Conclusion:
There are several equations for FeNO reference values that may be used in clinical practice, although the factors they include and the statistical methods they use vary considerably. We recommend the development of standard methods for the evaluation of normal FeNO data and that reference equations should be formulated based on a predetermined physiological model.
More Related Videos
08:23Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
08:44Dual Test Gas Pulmonary Diffusing Capacity Measurement During Exercise in Humans Using the Single-Breath Method
Published on: February 2, 2024
Related Concept Videos
01:19Respiratory Assessment: Purpose and Indications
Objectives and Importance:
The primary goal of respiratory assessment is to evaluate patients at early risk of clinical deterioration. Since respiratory distress often precedes other signs of declining health, breathing patterns and sounds become a...
01:17Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
01:19Special considerations while measuring oxygen saturation
Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.
01:23Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
01:20Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
01:19Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...