The importance of early diagnosis and treatment of incidental tension pneumothorax during robotic assisted laparoscopy for diaphragmatic endometriosis: a report of two cases

A 45-year-old nulliparous patient with a BMI of 25.6 and ASA grade II presented to the department with a diagnosis of deep endometriosis (ASMR IV ENZIAN :A3 B2 C3 FO FU FI). She was booked for a surgical treatment of pelvic and diaphragmatic endometriosis following suppression of menstruation with GnRH analogues. The planned surgery included a robotic laparoscopic resection of diaphragmatic lesions assisted by video- thoracoscopy. While pelvic inspection was being performed, an abrupt change in capnography (CO 2 ) was noted, concomitantly with arterial hypotension, maintaining adequate saturation of oxygen. With direct laparoscopic vision, multiple holes were found in the diaphragm in the endometriotic lesions, which acted as communicating lesions during hepatic mobilisation. As in the previous case immediate desufflation of the abdominal cavity and treatment of the tension pneumothorax were performed (puncture in the second intercostal space with a 14F venous catheter to decompress the lung) ( Figure 2 ). After drainage, capnography normalised immediately, with hemodynamic stabilisation. The surgery was uneventful, with an approach similar to case I, with robotic assisted laparoscopy and video-assisted thoracoscopy to treat the diaphragmatic disease. The patient was extubated in the operating room, without respiratory difficulties, and thoracic drainage was placed and maintained until the second postoperative day. — Thoracic drainage in case 1.

Intraoperative pneumothorax is a complication that can occur in patients with pelvic endometriosis treated with any kind of minimally invasive approach as diaphragmatic endometriosis is often under-diagnosed by imaging tests. The anesthesiologist and the surgeon should be aware that such a complication is a possibility for these patients and should be prepared to diagnose and treat this complication immediately.

The incidence of diaphragmatic endometriosis is uncommon and difficult to diagnose ( Andres et al., 2020 ). In most cases, it represents an incidental finding, with lesions observed by laparoscopy generally behind the right lobe of the liver ( Ceccaroni et al., 2012 ). Compatible with the literature, in both reported cases, the MRI examinations did not show the lesions. Diaphragmatic fenestrations in endometriotic tissue are described in the literature as a mechanism of pneumothorax formation, being responsible for 7.3-36% of cases of spontaneous catamenial pneumothorax ( Gil et al., 2020 ). Although it occurs on the right side in approximately 90% of cases, it can be on the left or bilateral ( Narula et al., 2018 ). Pelvic endometriosis is associated in 30- 51% of the cases ( Visouli et al., 2012 ; Segawa et al., 2011 ). Spontaneous pneumothorax formation in these patients is due to the transdiaphragmatic passage of air through the peritoneal cavity and its air, from the cervix during the menstrual period ( Frost et al., 2012 ). However, the opening of diaphragmatic fenestrations in endometriotic tissue during pneumoperitoneum has not yet been described in the investigated literature ( Ceccaroni et al., 2012 ). Video-laparoscopic treatment can lead to the incidental opening of small holes in the diaphragmatic endometrial tissue during surgical manipulation, even without direct tissue trauma, causing incidental pneumothorax. Intraoperative hypertensive pneumothorax is a serious event, with hemodynamic and respiratory repercussions, requiring immediate diagnosis and treatment The progressive increase in intrathoracic pressure, as a result of air trapping between the pleura, causes collapse of the affected lung and deviation of the mediastinum to the contralateral side, which interferes with venous return and ventilation (Zugliani et al., 2008). In both cases presented, the simple movement of the liver to visualise the lesions, associated with the maintenance pressure of the pneumoperitoneum, was enough to open communication channels in the endometrial tissue and the formation of tension pneumothorax, even without surgical manipulation of the endometriosis lesions. Diaphragmatic endometriotic tissue remains a possible route of communication with the chest, and with increasing pressures in the abdominal cavity, suspected pneumothorax should be considered with clinical signs suggest this. Capnography indirectly reflects the state of pulmonary circulation and CO 2 supply to the right heart chambers. Low cardiac output (shock) reduces perfusion of the alveolar segments, which therefore do not participate in gas exchange. Furthermore, collapse of the lung areas due to pneumothorax can lead to an abrupt decrease in EtC02 values on capnography, which is a warning sign found in diaphragmatic endometriotic resections. In the second reported case, no significant increase in airway pressure was detected, but the reduction in EtC0 2 values served as a parameter for diagnostic suspicion. In a case report of pneumothorax during anaesthesia for puncture of an ultrasound-guided breast tumor, reduction of EtCO 2 was also one of the first indicative signs of pneumothorax (Oliveira et al., 2004). Such conditions should be considered, since prompt diagnosis and treatment are necessary to avoid serious repercussions and even death. In both cases, thoracic drainage was chosen, which caused immediate normalisation of respiratory parameters and hemodynamic stabilisation, allowing surgery to continue.

Endometriosis is a disease characterised by a chronic oestrogen dependent inflammatory process that mainly affects the pelvic organs. Multiple theories have been postulated about its aetiology. One of the most accepted theories describes how the detached endometrial cells travel retrograde to the pelvic organs ( Bulun et al., 2019 ). In the vast majority of cases, the disease is found in the pelvis ( Andres et al., 2020 ). Extra-pelvic disease occurring in the upper abdomen including the diaphragm is rare and represents a diagnostic challenge. In these cases, robotic assisted laparoscopic surgery associated with video assisted thoracoscopy (VATS) is the best way of treatment ( Wolthuis et al., 2003 ). We describe two cases of robotic assisted laparoscopic surgery for the treatment of diaphragmatic endometriosis that developed an incidental tension pneumothorax during the visualisation of the lesions. Both were quickly treated using chest drainage.