Among patients scheduled for elective surgery at the Kyung Hee university Hospital, 15 patients undergoing open thoracotomy were selected. Two different ventilatory modes were employed and compared to the one-lung ventilation(control). First, 10
cmH2O
of continuous positive airway pressure was applied to the unventilated lung while patients were under one lung ventilation with 50% oxygen(CPAP 10 cmH2O). Second, 10 cmH2O of positive end expiratory pressure to the ventilated lung and 10 cmH2O of
continuous positive airway pressure to the unventilated lung were applied while patients were under one lung ventilation with 50% oxygen(CPAP/PEEP). Arterial oxygen tension, alveolar-arterial oxygen difference (A-aDO2) and intrapulmonary shunt
fraction
of two different ventilatory modes were observed and compared to control group, and CPAP/PEEP group to CPAP 10 cmH2O group.
@ES The results were as followed:
@EN 1) Mean PaO2 in CPAP 10 cmH2O and CPAP/PEEP were 138±42 mmHg and 177±44 mmHg, respectively, and were significantly increased as compared to 100±29 mmHg of control group(P<0.05). Comparing the PaO2 of CPAP 10 cmH2O and CPAP/PEEP, there was
statistically significant increase in CPAP/PEEP(P<0.05).
2) A-aDO2 in CPAP 10 cmH2O and CPAP/PEEP were 175±43 mmHg and 131±42 mmHg, respectively, and were significantly decreased as compared to 213±32 mmHg of control group(P<0.05). Shunt percentages(Qsp/QT) were measured as 23.7±5.8% in control
group.
18.3±6.0% in CPAP 10 cmH2O, 13.0±4.3% in CPAP/PEEP. Shunt percentages of CPAP 10 cmH2O and CPAP/PEEP were decreased significantly as compared to the control group(P<0.05).
Comparing the A-a DO2 and the shunt percentages of CPAP 10 cmH2O and CPAP/PEEP, there was statistically significant decrease in CPAP/PEEP(P<0.05).
Based on the above results, the application of appropriate continuous positive airway pressure to the unventilated lung and 10 cmH2O of positive end expiratory pressure to the ventilated lung during one lung ventilation is thought to be more
effective
than only continuous positive airway pressure to the unventilated lung in preventing hypoxemia. 9Korean J Anesthesiol 1995; 29: 414~422)
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