Background Multisite Near-infrared spectroscopy (NIRS) monitoring may help to detect circulatory failure in preterm infants. The aim of this study was to assess the correlation between multisite NIRS-measurements and routine haemodynamic measurements in preterm infants with clinical sepsis.
Methods Prospective exploratory cohort study in which preterm infants (GA2Leiden University Medical Centre, Leiden University, Leiden, Netherlands.
Background Heating and humidification of inspired gas is routine during neonatal non-invasive respiratory support, but little is known about the effects of different techniques on temperature and humidity in the upper airway.
Method Eight non-invasive respiratory support modes were applied to a neonatal manikin, in an incubator set to 34oC with relative humidity (RH) 60% (approximate normal upper airway conditions). Continuous positive airway pressure (CPAP), high-flow nasal cannulae (HFNC), and low-flow nasal cannulae (LFNC) devices were tested. Except for unhumidified LFNC, set humidifier temperature was 37oC. Typically used pressures and gas flows were assessed. Temperature and RH in the manikin’s oropharynx were measured every 5 min for 30 min, using a thermohygrometer. Each variation was repeated 3 times.
Results Steady state was reached by 10 min. Median values from 10–30 min are shown below.
Conclusions Achieved oropharyngeal temperature and RH varied between devices. RH of 0.8% occurred during LFNC using unconditioned ‘dry’ gas. Most devices achieved temperatures >34oC and >80% RH. Bubble CPAP delivered by Hudson prongs resulted in an oropharyngeal temperature above body temperature, which could result in water condensation as gas cools in the airway.