We appreciate the constructive comments by Dr. R. J. J. Verhage and colleagues regarding our study. They raised the issue of whether any statistical differences between the two groups were found with respect to intraoperative data and postoperative clinical outcomes. We agree with the comment that our study would have been of greater clinical interest if we had compared the postoperative outcomes of the different ventilation strategies. However, because the primary end point of our study was a comparison between the effects of pressure-controlled ventilation (PCV) and those of volume-controlled ventilation (VCV) during one-lung ventilation with the patients in the prone position for robot-assisted esophagectomy, we used a crossover design, which provides adequate statistical power with fewer patients. Regrettably, the crossover design does not permit such comparisons because VCV and PCV both were performed for each patient in random order. Therefore, our postoperative data on the incidences of pulmonary morbidities such as pneumonia and respiratory compromises were merely observational data without intergroup comparison. Additional operative and postoperative data are listed in Table 1. We hope our study can generate much interest and provide the basis for further clinical trials with a larger number of randomized patients to compare PCV and VCV. This would allow a more robust comparison of postoperative outcomes, which would add great value to the literature. The surgical technique of robot-assisted esophagectomy used in our study is fundamentally much the same as the technique extensively described by Dr. R. van Hillegersberg et al. [1]. To avoid redundant detail, we provided only a brief description of the surgical technique relevant to the primary end point of our study. The surgical technique of robot-assisted esophagectomy we used involved robot-assisted transthoracic en bloc esophagolymphadenectomy and laparoscopic gastric mobilization with upper abdominal lymph node dissection and cervical esophagogastrostomy. After induction of anesthesia, the patient was turned to the prone position. Four trocars were placed with inspection of the pleural space after carbon dioxide (CO2) insufflation at 8 to 10 mmHg. Trocar placement included a 12-mm trocar at the 8th intercostal space for a 30 angled 10-mm thoracoscope, an 8-mm trocar at the 6th intercostal space medial to the scapula for a right robotic arm, an 8-mm trocar at the 10th intercostal space for a left robotic arm, and a 12-mm trocar at the 9th intercostal space along the anterior axillary line for the accessory port. After docking of the da Vinci robotic cart (Intuitive Surgical, Mountain View, CA, USA) from the left cranial side of the patient, the right lung was collapsed and dissection began. The arch of the azygos vein was isolated and divided by an endoscopic linear stapler. The mediastinal pleura overlying the esophagus was incised, and the esophagus was circumferentially mobilized with a hook cautery. The upper thoracic esophagus was separated from Y. S. Choi J. K. Shim Y. J. Oh (&) Department of Anesthesiology and Pain Medicine and Anesthesia and Pain Research, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemun-Ku, Seoul 120-752, South Korea e-mail: yjoh@yuhs.ac