Rapid identification of spontaneously resolving capnothorax using bedside M-mode ultrasonography during laparoscopic surgery: the "lung point" sign -two cases report-
A 40-year-old woman, 169 cm, 57 kg, underwent laparoscopic right adrenalectomy due to an adrenal pheochromocytoma. Preoperative evaluation of the patient was unremarkable. General anesthesia was induced using thiopental sodium, fentanyl, vecuronium and sevoflurane. A 7.5 Fr 3-lumen catheter was inserted under ultrasonographic guidance (linear probe: UST-5546, 5-10 MHz, machine: Prosound SSD-4400®, Aloka Medical, Co., Ltd., Tokyo, Japan) into the right internal jugular vein, and lung sliding was confirmed in both thoraces. Next, the patient was placed into the left lateral decubitus position. Before incision, ETCO2, Pmax, and peripheral oxygen saturation (SpO2) were determined to be 33 mmHg, 17 cmH2O, and 100%, respectively. Pneumoperitoneum was established using CO2, intraabdominal pressure was maintained < 15 mmHg, and Pmax was 23 cmH2O at the time. Thirty minutes after inducing pneumoperitoneum, the ETCO2 and Pmax levels gradually increased to 43 mmHg and 30 cmH2O, respectively. Thereafter, SpO2 decreased acutely to 92%. On auscultation, the breath sounds from the left lung field were normal. However, the right side of the chest demonstrated no sounds. Immediately, the fraction of inspired oxygen (FiO2) increased from 0.5 to 0.8, and the endotracheal tube was withdrawn back to 2 cm in order to rule out endobronchial intubation. Because the depth of the endotracheal tube was 18 cm at the incisor teeth and confirmed the depth of endotracheal tube by cuff palpation at the sternal notch, we supposed that it was enough to rule out one-lung intubation without using bronchoscope. SpO2 was maintained at between 98-100%, though the right thorax was still silent. Pneumothorax was strongly suspected, and the chest was examined using ultrasonography. Lung sliding and seashore sign were demonstrated in the left lung (), however there was no sliding with barcode sign in the right lung (). Although the surgeon simultaneously inspected the diaphragm in detail, no apparent injuries or defects were found. Because the vital signs were stable and SpO2 and ETCO2 were normal, as indicated by an increased FiO2 and respiratory rate, the operation was laparoscopically completed.\nWhen the operation was concluded, a positive end-expiratory pressure (PEEP) of 5 cmH2O was applied to inflate the collapsed lung. The patient was examined using ultrasonography whilst in the supine position, and at the same time, portable chest radiography was called to assess a pneumothroax. The ultrasonographic probe was placed on the right lower lateral chest wall between anterior and mid axillary line (), and we identified the "lung point" sign, which can be used to diagnose pneumothorax []. Also, chest radiography indicated a < 30% collapse of the right lung (). As the right hemithorax was continuously examined using ultrasonography, auscultation of the right lung improved, as well as the appearance of lung sliding sign and the disappearance of the lung point sign in whole right hemithorax within about 30 minutes after the end of the operation. No hemodynamic instability was noted, and SpO2 was maintained at 100% using only medical air. Hence, pneumthorax was considered to be capnothorax, and the patient was extubated without the insertion of a chest tube. The patient was transferred to the postanesthetic care unit (PACU) and did not complain about any respiratory disturbance.