The following is the summary of “Performance of Invasive Mode in Different Heated Humidification Systems With High-Flow Nasal Cannula” published in the December 2022 issue of Respiratory Care by Plotnikow, et al.

High-flow nasal cannula oxygen therapy induces physiologic changes that affect ventilatory factors. Still, researchers know that inhaling gases negatively affects the airway mucosa. Using high-flow oxygen therapy at flows between 30 and 100 L/min, this study aimed to compare the absolute humidity, relative humidity, and temperature performance of several brands of heated humidifiers and circuits in the invasive mode. From September 5th to October 20th, 2019, investigators will perform a prospective observational study at the laboratory for analyzing equipment at Sanatorio Anchorena.     

The results showed a statistically significant interaction between the scheduled flows and the various combinations of devices and circuits for the supply of absolute humidity (P<.001). Delivered absolute humidity was shown to be affected by flow regardless of the equipment and circuit combination (P<.001). Absolute humidity values of more than 33 mg/L were consistently reached or achieved at flows up to 100 L/min when the Fisher & Paykel MR850 heated humidifier was used in conjunction with the Medtronic-Dar circuit, the Intersurgical circuit, and the AquaVENT circuit in the invasive mode. Results were comparable when using the Flexicare FL9000 heated humidifier with the Fisher & Paykel RT202 circuit, the Fisher & Paykel Evaqua 2 circuit, the Flexicare circuit, the AquaVENT circuit, and the GGM circuit. 

There was no significant difference between the circuit and programmed flows, and the absolute humidity given in the invasive mode (36.2±5.9 mg/L) was higher than the noninvasive mode (26.8 ±7.2 mg/L) (P<.001 for both). Absolute humidity during invasive high-flow oxygen therapy was dependent on the planned flow and the heated humidifiers and circuit combination, particularly at flows more than 50 L/min. And the heated humidifiers acted in varying ways, sometimes failing to provide sufficient humidity. On the other hand, switching to the invasive mode boosted the efficiency of several devices.