Among the many available ventilation methods, high frequency jet ventilation(HFJV) induces adequate gas exchange with tidal volumes smaller than those of conventional ventilation. During anesthesia HFJV may reduce the patient's movement in the
operating
field, which produces the better condition. In critically ill patient HFFV reduces the unwanted hemodynamic effects of conventional ventilation caused by the increase in intrathoracic pressure. But general anesthesia with jet ventilator has been
only
dependent on intravenous anesthetics. Therefore this study was performed by use of entrained N2O and enflurane with jet ventilator, Firstly, in vitro study, the changes of minute ventilation and N2O and enflurane with jet ventilator. Firstly, in
vitro
study, the changes of minute ventilation and N2O concentration were measured according to the changes of driving pressure, ventilatory frequency, inspiratory ratio of jet ventilator and N2O flow. Secondly, in vivo study, enflurane anesthesia with
HFJV
were perforemd to the 10 patients in ASA class I or Ii who underwent laryngeal microsurgery under the diagnosis of laryngeal nodule from june to August 1992, and the changes of blood pressure, heart rate and ABGA of postinduciton period were
measured
and compared with those of preinduction period.
@ES The results were as follows:
@EN 1. At 1.4, 2.1 2.8 kg/㎠ of driving pressure(DP) minute ventilation (MV) was increased to 15.9, 18.0, 20.2 L/min and N2O concentration was decreased to 41, 34, 29% respectively when ventilator was fixed to 40 bpm of ventilatory frequency(VF),
30% of
inspiration ratio(IR) and 6L/min of N2O flow.
2. At 20, 30, 40% of IR, MV was increased to 15.5, 18.0, 21.2L/min and N2O concentration was decreased to 42, 34, 27%, respectively when jet ventilator was fixed to 40 bpm of VF, 2.1kg/㎠ of DP and 6L/min of N2O flow.
3. At 2, 4, 6, 8 L/min of N2O flow, MV was increased to 14.6, 16.2, 18.0 20.2L/min and N2O concentration was increased to 15, 26, 34, 40%, respectively when jet ventilator was fixed to 40 bpm of VF, 30% of IR and 2.1kg/㎠of DP.
4. The inspired concentration of N2O and enflurane were 34% and 1.3 to 1.7%, respectively and MV was 18.0L/min when jet ventilator was fixed to 30% of IR, 40 bpm of VF, 2.1kg/㎠ of DP, 6L/min of N2O flow rate and 4~5% of enflurane concentration.
5. There were no significant changes in systolic BP, but diastolic BP, mean arterial pressure and heart rate increased significantly during inhalational anesthesia(p<0.05).
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