High frequency jet ventilation(HJFJV) administered through a thin catheter instead of standard endotracheal tube provides improved operation field during laryngeal microsurgery. In this study, effect of changes in inspiration time and frequency
on
gas
exchange was observed. Sixty five patients(ASA class 1~2) underwent laryngeal microsurgery were divided into 3 groups according to inspiration time(50%, 40%, and 30%) and then subdivided into 3 groups according to frequency(3.3 Hz, 2.5Hz and
1.7Hz).
Driving pressure was same in all groups(2.4kg cm²). Anesthesia was induced with thiopental sodium, fentanyl and succinylcholine with 100% oxygen mask ventilation and maintained with intermittent intravenous anesthetics during jet ventilation via
10 Fr.
Catheter with 100% oxygen. Jet cannular was located cm proximal to carina. Arterial blood gas analysis and hemodynamic date(blood pressure and heart rate) were measured at 0 minute(just after catheter intubated and jet ventilation started), 5
minute, 10
minute and after then, every 10 minutes.
There was significant change in PaCO2 by varing inspiration time but, no significant change by frequency except in group of 3.3 Hz at inspiration time 40% and 30%. Number of patients who showed in excess of 45 mmHg of PaCO2 at 20 minute were 2
out
of
19,9 out of 23 and 9 out of 23 in inspiration time 50%, 40% and 30%, respectively.
In summary, HFJV via thin catheter located l cm proximal to carina during laryngeal microsurgery can be done safely with inspiration time 50% under good operation field at driving pressure 2.4kg/cm²and frequency 3.3, 2.5 and 1.7 Hz.
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