Objective: Adequacy of criteria for Lt DLT size in the determination of RT DLT size before thoracic surgery.

Methods: A prospective, controlled, comparative study. After obtaining informed consent, male and female patients over 18 years of age , candidates for elective thoracic surgery obliging DLT intubation, will be enrolled in the study. Children, pregnant and mentally incompetent patients will not be included.

Preoperative evaluation will be performed by an anesthesiologist and the patients will receive premedication with respect to the planned operation and concurrent disease status. The age, gender, height and weight of the patient will be recorded. On the chest CT series, measurements of the tracheal length and diameter, both main bronchial, and RUL bronchial orifice diameter in millimeters will be performed, using an universal measurement system .

All patients will receive intravenous induction with Fentanyl 3-5 mcg/kg, Propofol 2-2.5 mg/kg, and Rocuronium 0.6-0.8 mg/kg. All patients will be intubated by the same anesthesiologist. Fiberoptic bronchoscopy will be performed for proper positioning of the DLT.

Accordingly to the indication , patients will be intubated with Lt or Rt DLT -Mallinkrodt Broncho-cath, routinely used for this kind of operations.

Patients scheduled for right lung operation will be intubated with Lt DLT. The size of the Lt DLT will be determined accordingly to the guidelines, in correlation with patient's height and CT measurements . Lt DLT intubation will be performed by the generally accepted technique, under FOB control. In case the Lt DLT size will prove to be inappropriate , a smaller/larger DLT will be inserted, accordingly.

Patients scheduled for left lung operation will be intubated with Rt DLT. The size of the Rt DLT will be determined in correlation with patient's height and CT measurements, accordingly to the guidelines for Lt DLT size . In case the Rt DLT positioning is impossible due to inappropriate adjustment of the ventilation slot against the RUL bronchus orifice and/or tracheal protrusion of the bronchial cuff, the Rt DLT will be substituted by a smaller/larger Rt DLT , respectively.

The number of attempts on intubation and repositionings of the DLT during surgery will be recorded.

The volume of air in the bronchial and tracheal cuff will be recorded. Information about the adequacy of lung separation will be obtained by the surgeons.

Postoperative clinical and X-ray follow up will be performed about lung recruitment and ventilatory complications ( atelectasis, pneumonia) Throughout the study no additional x-ray or laboratory checkup will be required, and no additional invasive procedures or treatment will be performed, than the usually accepted.

Statistical analysis of collected clinical and rentgenologic data will be performed .