High-frequency jet ventilation (HFJV) provides a good surgical field for laryngomicrosurgery. However, since measurements of end-tital CO
2 and tidal volume are difficult to obtain during HFJV, it may cause hypercapnea. We examined the effects of driving pressure, inspiratory time and the fraction of inspired oxygen (FiO
2) on arterial blood gas analysis with 125 adult ASA I - II patients. Ventilation frequency was fixed at 2Hz in all groups. PaO
2 was lower in the driving pressure 1.5 kg/cm
2 group in comparison with the driving pressure 2.0kg/cm
2 group. In the group with 30% inspiratory time, CO
2 elimination decreased in comparison with the 50% inspiratory time group at driving pressure either 1.5kg/cm
2(PaCO
2 50 vs 46mmHg) or 2.0kg/cm
2(51 vs 45mmHg) (p<0.05) . The FiO
2 0.6 group showed lower and normal PaCO
2 (39mmHg) in comparison with the FiO
2 1.0 groups, and good oxygenation. The results suggest that HFJV with FiO
2 0.6, driving pressure 2.0kg/cm
2, and 50% inspiratory time is optimal for laryngomicrosurgery in patients without obstructive pulmonary diseases.
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