The use of lung‐ultrasound to confirm correct placement of left sided double lumen tubes
Study objective: To assess the accuracy of the ultrasonographic lung sliding sign in detecting correct positioning of the endotracheal double‐lumen tube after intubation, compared to flexible bronchoscopy, in adult patients who present for thoracic surgery requiring one lung ventilation. Design: Prospective clinical study. Setting: Cardiothoracic theatre, Universitas Hospital, Bloemfontein. Patients: 30 adult patients, 18 years of age or older, who present for elective thoracic surgery, and require endotracheal left sided double‐lumen tube intubation after induction of anaesthesia for lung isolation. Intervention and measurement: The presence of the lung sliding sign was determined with an ultrasound on all 30 patients before induction of anaesthesia and after intubation, as well as post lung isolation. All patients were intubated with a left sided double‐lumen tube. The Anaesthetic consultant or registrar then performed a flexible bronchoscopy on all patients to verify the position of the double‐lumen tube. Results: A total of 17 patients were enrolled in the study. 1 Patient was excluded who was less than 18 years of age. In 1 case no bronchoscope was available to confirm correct position of the double‐lumen tube. In 11 cases the presence of the lung sliding sign pre‐intubation on the affected side was absent, and thus could not be used in comparing ultrasound findings with bronchoscopy. The overall sensitivity of the ultrasonographic lung‐sliding to confirm correct placement was 94.1% (confidence interval 73.0 to 99.0%). The positive predictive value was 100%. Conclusion: The presence of the lung‐sliding sign before induction of anaesthesia was absent in a high number of patients (37.9%). Our study suggests that, for patients with the presence of the lung‐sliding sign pre‐induction of anaesthesia, the ultrasonographic lung‐sliding sign can accurately detect correct positioning of the double‐lumen tube as compared to the gold standard which is a flexible bronchoscope. We therefore recommend that patients should first be assessed for the presence of lung‐sliding pre‐intubation before deciding on ultrasound as the means to confirm correct double‐lumen tube placement. Ultrasound will therefore not be able to replace bronchoscopy in thoracic surgery.