Related Experiment Video
Updated: Aug 15, 2026

Delivery of In Vivo Acute Intermittent Hypoxia in Neonatal Rodents to Prime Subventricular Zone-derived Neural Progenitor Cell Cultures
Published on: November 2, 2015
Is neonatal inspired gas humidity accurately controlled by humidifier temperature?
M O'Hagan1, E Reid, W O Tarnow-Mordi
1Department of Child Health, University of Dundee, Ninewells Hospital and Medical School, UK.
Objective:
To investigate: a) the relationship between humidifier temperature and inspired gas humidity and b) the effect of insulating the inspiratory tube on "rainout" (condensate).
Design:
Observational study.
Setting:
Regional neonatal unit in a university hospital.
Patients:
Forty-eight infants receiving assisted ventilation, of whom 31 infants were nursed in incubators and 17 under radiant heaters.
Measurements And Main Results:
Despite always maintaining humidifier temperature greater than 34.7 degrees C, inspired gas humidity decreased below the American National Standards Institution minimum of 30 mg H2O/L on 35 of 479 occasions. At a humidifier temperature of 36 degrees C, inspired gas humidity varied between 17 and 43 mg H2O/L. In incubators set at a temperature of 34.1 +/- 1.3 (SD) degrees C, inspired gas humidity was linearly related to humidifier temperature, but with wide scatter (p less than .001, r2 = .28). In cooler incubators set at 32.9 +/- 1.8 degrees C, inspired gas humidity varied inversely with humidifier temperature. This variation was attributed to condensate due to inspired gas cooling within the incubator. Insulation of the inspiratory tubing reduced condensate by only 15%.
Conclusions:
Inspired gas humidity cannot be predicted reliably from humidifier temperature. Accurate control will require a new generation of humidifiers that measure inspired gas humidity.
More Related Videos
Related Concept Videos
Assessment 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:
Physiological 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...
Physiology of Respiration II: Neurogenic Control of Respiration
Central Control
The brainstem is the primary site of central control, hosting respiratory centers:
Administering Oxygen by Nasal Cannula
Nasal Cannulas
A nasal cannula is a lightweight tube split into two prongs placed in the nostrils, connected...
Mechanical Ventilation I: Indication and Settings
Bioreactor Controls-I

