Positive end-expiratory pressure applied to the dependent lung during one-lung ventilation improves oxygenation and respiratory mechanics in patients with high FEV1.
OBJECTIVE
The aim of this study was to test the efficacy of positive end-expiratory pressure (PEEP) to the dependent lung during one-lung ventilation, taking into consideration underlying lung function in order to select responders to PEEP.


METHODS
Forty-six patients undergoing open-chest thoracic surgical procedures were studied in an operating room of a university hospital. Patients were randomized to receive zero end-expiratory pressure (ZEEP) or 10 cmH2O of PEEP to the dependent lung during one-lung ventilation in lateral decubitus. The patients were stratified according to preoperative forced expiratory volume in 1 s (FEV1) as an indicator of lung function (below or above 72%). Oxygenation was measured in the supine position, in the lateral decubitus with an open chest, and after 20 min of ZEEP or PEEP. The respiratory system pressure-volume curve of the dependent hemithorax was measured in supine and open-chest lateral decubitus positions with a super-syringe.


RESULTS
Application of 10 cmH2O of PEEP resulted in a significant increase in PaO2 (P < 0.05). This did not occur in ZEEP group, considered as a time matched control. PEEP improved oxygenation only in patients with high FEV1 (from 11.6+/-4.8 to 15.3+/-7.1 kPa, P < 0.05). There was no significant change in the low FEV1 group. Dependent hemithorax compliance decreased in lateral decubitus, more in patients with high FEV1 (P < 0.05). PEEP improved compliance to a greater extent in patients with high FEV1 (from 33.6+/-3.6 to 48.4+/-3.9 mLcmH2O(-1), P < 0.05).


CONCLUSIONS
During one-lung ventilation in lateral decubitus, PEEP applied to the dependent lung significantly improves oxygenation and respiratory mechanics in patients with rather normal lungs as assessed by high FEV1.
Valenza
F
F
Istituto di Anestesia e Rianimazione, Milan, Italy.
Ronzoni
G
G
Perrone
L
L
Valsecchi
M
M
Sibilla
S
S
Nosotti
M
M
Santambrogio
L
L
Cesana
B M
BM
Gattinoni
L
L
D000704:Analysis of Variance; D001784:Blood Gas Analysis / Q000379:methods; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011175:Positive-Pressure Respiration / Q000379:methods*; D011187:Posture / Q000502:physiology; D012121:Respiration, Artificial / Q000379:methods*; D012129:Respiratory Function Tests / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology*; D019616:Thoracic Surgical Procedures / Q000379:methods; D016896:Treatment Outcome
D010100:Oxygen