Monitoring of Tracheal CO2 Tension during High Frequency Jet Ventilation for Laryngomicrosurgery / 대한마취과학회지

BACKGROUND: The monitoring of end-tidal CO2 tension (PETCO2) during high frequency jet ventilation (HFJV) has been unsatisfactory because of a small tidal volume and slow response time of CO2 analyser, although several authors have reported strategies of successful PETCO2 measurement during HFJV. The aim of this study was to assess the validity of tracheal CO2 tension (PtCO2) as a PaCO2 during HFJV. METHODS: We studied 24 patients undergoing laryngomicrosurgery during HFJV (rates: 100/min; I:E= 0.2; driving pressure: 0.25-0.35 MPa) through a 12 Fr. polyethylene injector placed 6-7 cm below the vocal cord. A gas sampling line was placed longitudinally against the injector and they were wrapped with aluminum foil. Continuous capnography was recorded during 20 minutes of HFJV. Every 5 minutes of HFJV, PtCO2 was obtained from the plateau value of CO2 wave after the stopping of JV and arterial blood gas analysis was done at 20 minutes of HFJV comparing PaCO2 to PtCO2. A Pearson's product moment correlation and regression analysis between PtCO2 and PaCO2 and the agreement between the two methods using Bland-Altman method were assessed. RESULTS: A regression analysis (R2=0.928) and a Pearson's product moment correlation (r=0.965, P<0.001) indicated a strong correlation of PtCO2 and PaCO2 during HFJV. The difference against a mean scatter diagram showed a relative good agreement between the two method (mean difference: 1.58 (SD 2.22) mmHg; limit of agreement: 2.86 and -6.02). CONCLUSIONS: PtCO2 obtained from a plateau of CO2 wave on capnography after interruption of HFJV can accurately reflect PaCO2 during HFJV in relative.

The Comparison of High Frequency Jet Ventilation and/or Conventional Mechanical Ventilation in Dogs / 대한마취과학회지

BACKGROUND: High frequency jet ventilation (HFJV) which can be replaced conventional mechanical ventilation (CMV) is another method in respiratory care. But, each one has weakness. This study was designed to determine whether combined HFJV with CMV is more prominent than HFJV on cardiopulmonary system. METHOD: Korean mongrel dogs (n=11) were induced with thiopental sodium 10 mg/Kg, intravenously. Tracheal intubation was performed, and CMV (respiratory rate 30/min, VT 10 ml/Kg, FiO2 1.0) was applied. After placement of monitors, arterial blood pressure (BP), heart rate (HR), central venous pressure (CVP), cardiac output (CO), pulmonary capillary wedge pressure (PCWP) were measured for control values on steady state of vital signs. Thereafter, HFJV was done using respiratory rate 120/min, inspiratory time 30 %, driving pressure 40 psi for 60 min (examed at time of 15, 30, 60 min), and then CMV was supplemented to HFJV using VT 10 ml/Kg, respiratory rate 8, 4, 2, 1, 0.5/min for 150 min (examed at time of 30, 60, 90, 120, 150 min). All values were measured and analyzed on suggested times according to the different ventilatory modes. RESULT: Arterial BP, HR, CO, CVP and PCWP were not changed significantly during the 60 minutes of HFJV. PaCO2 was increased significantly from 33+/-9 mmHg to 45+/-12 mmHg (p<0.05) and arterial pH was decreased significantly from 7.39+/-0.10 to 7.29+/-0.11 (p<0.05) after 60 minutes of HFJV. PaO2 was not changed for HFJV. Variables (BP, HR, CO, CVP and PCWP) were not changed significantly after combined HFJV with CMV at each respiratiry rates. Elevated PaCO2 at the 60 minutes of HFJV was normalized after combined HFJV with CMV at respiratory rate of 8, 4, 2, 1, 0.5/min. (p<0.05) and decreased pHa was also normalized (p<0.05) after combined HFJV with CMV at respiratory rate of 8, 4, 2, 1/min. PaO2 was not changed for the time which we combind HFJV with CMV. CONCLUSION: The combinded HFJV with CMV makes expected arterial oxygenation and prevents accumulation of arterial carbon dioxide without depressive effect on cardiovascular system, when tidal volume of CMV is 10 ml/Kg and the respiratory rate is above 1/minute. So, this study suggests that the combined HFJV with CMV may be applied to respiratory failure effectively.

Application of HFJV in Tracheal Stenosis / 대한마취과학회지

Due to the increased use of tracheostomy and intermittent positive pressure ventilation, patients with trscheal stenosis have become more frequent. Recently we experienced a patient with tracheal stenosis who was tracheostomized upon admission, but unfortunately the stenotic lesion was located below the end of the tracheostomy tube. The stenotic lesion was l.6cm above the carina, its diameter was 0.5 cm, and the length of the stenotic segment was about 2cm, A3,5 mm(I.D.) endotracheal tube was passed through the stenotic lesion via the tracheostomy site, and high frequency jet ventilation was applied with a swivel connector. Immediately after the start of surgery, CO2retention occurred and the driving gas pressure increased from 4p to 5p psi, the I:E ratio from 1:2 to 1: 3, but the respiration rate (100 bpm) was maintained as before. CO2retention was relieved soon. Following end to end anastomosis a 6. 0 mm(I.D.) cuffed endotracheal tube was intubated orally and inhalation anesthesia using N2O-O2-Halothane was maintained until the surgery was completed.