Effect of ultrasonic nebulization on blood gas tensions in chronic obstructive lung disease.

Ultrasonic nebulization therapy (U/air) resulted in a decline in Pa02 of -5 to -22 rnm H g in ten of 15 chronic obstructive lung disease (COLD) patients. A similar decline in Pa02 occurred in four of ten COLD patients when ultrasonic nebulization was given with intermittent positive pressure breathing (IPPB [IPPB/U/air]). Complaints of discomfat from treatment were elicited in ten of 15 COLD patients treated with U/air and all ten COLD patients treated with IPPB/U/air. No consistent correlation of symptoms with the changes in Pa02 was noted. The increase in airway resistance with ultrasonic nebulization which occurs only in patients with COLD probably best explains the complaints, since our control patients had a greater incidence and degree of Pa02 decline and yet remained free of discomfort. Respiratory alkalosis was noted in one of 15 and three of ten COLD patients treated with U/air and IPPB/U/air, respectively. Hypoventilation with a decrease in Pat32 and pH and a rise in PaCOz occurred in two patients receiving U/air. The mechanisms for the reduction in PaOz are complex, including hypoventilation, increased workload of breathing, and most commonly, ventilation perfusion abnormalities. Acute blood gas changes are common with ultrasonic therapy and have important clinical implications which must be evaluated along with other known hazards of inhalational therapy.