Pulmonary resistance and methods of humidification in acute pulmonary failure

In order to evaluate the effects of ultrasonic nebulization on airway resistance in respiratory failure, ten patients requiring mechanical ventilation for acute pulmonary failure were each ventilated with two humidification systems, one producing inspired air saturated with vapour at 35 degrees C, the other nebulizing water droplets ultrasonically. There was no statistically significant difference in pulmonary resistance at inspiratory flow rates of 40, 60, AND 80 1/min. A separate comparison between humidifiers in those patients with the highest resistances did not reveal any difference in response to method of humidification. In contrast to studies in other contexts, these data fail to show any significant difference, from the standpoint of effects on resistance, in the use of ultrasonic mist humidification during mechanical ventilation for respiratory failure.