Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in patients with low diffusion capacity of lung for carbon monoxide: a crossover study.
OBJECTIVE
To investigate the effects of a 1:1 inspiratory-to-expiratory (I:E) ventilation ratio on oxygenation and respiratory mechanics during one-lung ventilation (OLV) in patients with low diffusion capacity of lung for carbon monoxide (DLCO).


METHODS
Prospective, randomized, crossover study.


METHODS
Operating room, university hospital.


METHODS
Twenty-six patients with a preoperative DLCO less than 80% who were scheduled for lung lobectomy requiring OLV under general anesthesia.


METHODS
In the first group (n = 13), OLV was begun with a 1:1 I:E ratio, which was switched to a 1:2 I:E ratio after 30 minutes. In the second group (n = 13), the modes of ventilation were performed in the opposite order. Pressure-controlled ventilation with 5 cm H2O of positive end-expiratory pressure and a tidal volume of 5 to 8 mL/kg was applied during OLV.


METHODS
Arterial and central venous blood gas analyses were recorded and used to calculate intrapulmonary shunt fraction and physiologic dead space. These measurements were taken at 4 time points: 10 minutes after two-lung ventilation in the lateral decubitus position, 30 minutes after initiation of OLV, 30 minutes after switching the I:E ratio, and 10 minutes after two-lung ventilation was resumed.


RESULTS
There was no difference in arterial oxygen tension during OLV between the 2 groups (P = .429). Arterial carbon dioxide tension and peak airway pressure were lower in the 1:1 group than in the 1:2 group (P = .003; P = .008). Physiologic dead space was also decreased in the 1:1 I:E ratio group (P = .003). Mean airway pressure and dynamic compliance were higher in the 1:1 group (P = .003; P = .007).


CONCLUSIONS
Pressure-controlled ventilation with a 1:1 I:E ventilation ratio did not improve oxygenation in patients with low DLCO during OLV compared with a 1:2 I:E ventilation ratio. However, it did provide benefits in terms of respiratory mechanics and increased the efficiency of alveolar ventilation during OLV.
Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Kyuho
K
Lee
Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Young Jun
YJ
Oh
Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Yong Seon
YS
Choi
Department of Anesthesiology and Pain Medicine, Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea. Electronic address: tessar@yuhs.ac.
Shin Hyung
SH
Kim
D000328:Adult; D000368:Aged; D002248:Carbon Monoxide / Q000378:metabolism*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D061810:One-Lung Ventilation / Q000379:methods*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D011653:Pulmonary Diffusing Capacity; D012126:Respiratory Dead Space; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D013990:Tidal Volume; D055815:Young Adult
D002248:Carbon Monoxide
One-lung ventilation; inspiratory-expiratory ratio; oxygenation; respiratory mechanics