a 62-year - old man , 170 cm , 72 kg , with early gastric cancer diagnosed during a medical inspection 1 month earlier was admitted to hospital for a laparoscopic gastrectomy . there was nothing in his medical record except for having taken medication for hypertension that was found in a medical inspection . a preoperative chest x - ray , pulmonary function test and electrocardiogram showed normal findings . premedication was not administered , and the vital signs measured upon arrival showed a blood pressure ( bp ) , heart rate ( hr ) and saturation of peripheral oxygen ( spo2 ) of 140/90 mmhg , 65/min and 99% , respectively . fentanyl 0.1 mg and thiopental 325 mg were administered with 100% inspired oxygen through the anesthetic mask . after confirming a loss of consciousness , endotracheal intubation was performed after an intravenous injection of succinylcholine 70 mg . after ventilation of both lungs had been confirmed , the tube was fixed to the incisal tooth at a depth of 23 cm , and vecuronium 6 mg was administered for muscle relaxation . arterial puncturing was performed at the left radial artery for invasive monitoring of the arterial blood pressure . anesthesia was maintained with oxygen 1.5 l / min , air 1.5 l / min , and sevoflurane 1.5 - 3.0 vol% , while the muscle relaxant was administered intermittently . mechanical ventilation was performed with a tidal volume ( tv ) respiratory rate ( rr ) and peak airway pressure ( pmax ) of 500 ml , 12/min , and 16 cmh2o , respectively . after inducing anesthesia , the partial end - tidal carbon dioxide pressure ( petco2 ) , bp , hr and spo2 was 37 mmhg , 130/90 mmhg , 80/min and 99% , respectively . for laparoscopy , a total of 5 trocars ( 3 of 5 mm , 11 mm , and 12 mm ) were inserted and an 11 mm hasson trocar was connected to a carbon dioxide gas pump ( co2 endoflator , olympus , japan ) . to secure the operative view and space , 12 mmhg of co2 was provided and the patient was turned to the reverse trendelenburg position , and the operation proceeded . the pmax after the pneumoperitonium was 22 cmh2o , and the petco2 was 38 mmhg . approximately 70 minutes after the pneumoperitonium , the pmax increased suddenly to 30 cmh2o , and then endotracheal suction was performed to exclude the effect of endotracheal excretion but the amount excreted was small . subsequently , the pmax was maintained at the higher 30 cmh2o , and the spo2 decreased to 96% . his vital signs then showed a petco2 , bp , and hr of 39 mmhg , 110/60 mmhg and 75/min , respectively , while the arterial blood gas analysis ( abga ) indicated a ph , partial pressure of arterial carbon dioxide ( paco2 ) and pao2 of 7.37 , 48 mmhg and 118 mmhg , respectively . upon auscultation , the breathing sound of the right side was normal but the breathing sound of the left lung decreased significantly . manual ventilation was performed to preclude the tube from moving into the bronchus and the endotracheal tube was withdrawn back to 4 cm with auscultation . however , the breathing sound of the left lung still decreased . there were no significant changes in the patient 's bp and hr , but the friction of inspired oxygen ( fio2 ) was increased and another abga was used under consideration of the incidence of pneumothorax . the results indicated a ph , paco2 and pao2 of 7.33 , 53 mmhg and of 105 mmhg , respectively . the pneumoperitonium was terminated immediately and a chest x - ray ( chest ap view ) was performed . the findings on the chest x - ray confirmed the incidence of pneumothorax in the left lung ( fig . 1 ) , and 12-french catheter ( trocar catheter , mallinckrodt medical inc , ireland ) was inserted along the midaxillary line into the space between the 5 and 6 rib after consulting with the surgeon . after catheterization , the pmax was decreased to 24 cmh2o and the breathing sound of the left lung showed a favorable change . the abga findings indicated a ph of 7.37 , a paco2 of 44 mmhg , and a pao2 of 158 mmhg , indicating significant improvement . after confirming the stability in the patient and performing a pneumoperitonium with the same gas pressuring pressure for the operation , the fio2 was reduced to 0.6 and mechanical ventilation the measured abga showed a ph , paco2 and pao2 of 7.39 , 44 mmhg , 192 mmhg , respectively , whereas the pmax and petco2 was 24 cmh2o and 32 mmhg , respectively . after his spontaneous respiration returned , muscle relaxation was achieved using a mixture of glycopyrrolate 0.4 mg and neostigmine 2 mg , and the endotracheal tube was removed after he reached consciousness . the patient did not complain of any discomfort or respiratory disturbance except for surgical site pain , and he was transported to the post - anesthesia recovery unit . oxygen at 5 l / min was administered through a venturi mask when the pulse oximetry indicated a spo2 of 99% . after the patient 's consciousness returned to normal , he was transferred to the ward while oxygen of 3 l / min was provided through a venturi mask . a chest x - ray performed on the chest pa view confirmed a considerable decrease in the pneumothorax ( fig . on postoperative day 4 , the catheter was removed , and on postoperative day 6 , a chest x - ray and computerized tomography ( ct ) did not show any abnormal findings . pneumoperitonium , which is employed as a key step during a laparoscopy , can reduce the patient 's residual volume , cause a high airway pressure and hypercapnia , as well as hemodynamic changes to senior patients with underlying disorders in the cardiovascular system . sometimes , pneumoperitonium not only affects the pulmonary function caused by the abdominal pressure , but also causes pneumothorax due to air flow into the thoracic cavity . the causes of pneumothorax during laparoscopy can be divided into cases in whom organic damage can and can not be identified . the causes for pneumothorax with organic damage involves iatrogenic damage on the pleura , diaphragm , or hiatal hernia , and rupture in the alveolus , particularly which can be triggered by the presence of blebs or bullae in the lung , or by the incidence of barotraumas during mechanical ventilation . the following events are suspected to be the cause of pneumothorax without organic damage : the remains of congenital deficits between the abdominal cavity , pleura , and pericardium ; movement of gas into the chest septum or the pleural cavity through the retroperitoneal space ; gas leakage by a high gas pressuring pressure ; and a long length of surgery time on vulnerable spots in the aortic or esophageal hiatus . regardless of the underlying cause , the symptoms of pneumothorax during laparoscopy vary from a minor case to serious ones in terms of the clinical features . a review of the literature also revealed a particular case , in which an operation encountered complete unilateral pulmonary collapse but with no increase in pmax , nor any significant clinical signs on petco2 and spo2 , so the surgery proceeded uneventfully . such diversity in the symptoms of pneumothorax comes is due to the influence on the cardiovascular system being dependent on the size and developmental rate of the pneumothorax , as well as the existent cardiopulmonary function of the patients . hence , the symptoms of the cases with organic damage are expected to be more rapid and severe . therefore , an immediate diagnosis and proper treatment by the anesthesiologist is critical for the safety of patients . in this case , we detected abnormal findings by the increase in pmax and decrease in spo2 at the beginning of the procedure , and confirmed the pneumothorax by a chest x - ray while excluding an obstruction of endotracheal tube due to excretions , patient 's spontaneous respiration , and migration of the tube into the bronchus . a study result , where changes in the qrs wave ( detector describing the electrocardiographic features ) of the precordial electrocardiogram recognize the incidence of an artificial pneumothorax in experiments , would be also useful for an earlier diagnosis of pneumothorax . however , there are no clinical findings yet , and this case did not show such changes in the qrs wave . pneumothorax has a high incidence in cases of a long operating time of 200 minutes or more , when > 15 mmhg on the pneumoperitonium is maintained , a petco2 > 50 mmhg , and operations such as fundoplasty or hiatal dissection , etc . . in this case , the operation proceeded with a pmax of 12 mmhg , which was reported to minimize the hemodynamic changes , such as a decrease in cardiac output , instead of a pmax of 10 mmhg reported in the literature in order to be free of any complications caused by the pneumoperitonium . during the operation , we encountered the pneumothorax despite a petco2 of 40 mmhg or less and a short duration of the pneumoperitonium , 70 min . based on the fact that after a postoperative ct on the chest , there were no findings of underlying disorders in the lung , and that the intraoperative observations and post - operative video reconfirmation did not reveal any iatrogenic damage nor exposure of the retroperitoneal space , we suspected air intrapleural influx through a congenital deficiency , such as a peripheral fragile region of the pleura , or a hiatus between the pleura and the peritoneum . among the 220 cases of laparoscopic surgery performed at our institution during the last three years that had a pmax of 15 mmhg or more and an operating time of 3 hours or more , there have not been any incidences of severe pneumothorax requiring air release , as in this case . therefore , the presence of anatomical defect is considered to be a more important factor in the occurrence of pneumothorax than any other factors , which will need further data and research . in addition , the use of a relatively low gas pressuring pressure , such as that used in our case , would help relieve the cardiovascular suppression , but it can not totally reduce the incidence of pulmonary complications , such as pneumothorax . in most cases of pneumothorax , it is a primary step to resolve pneumoperitonium . when a patient returns to a stable condition , the operation should proceed with a lower gas pressuring pressure . however , decompression through positive end - expiratory pressure ( peep ) or thoracentesis should be attempted when such a reduction of the pressure fails to bring the patient back to the stable condition . in emergent cases in this case , the chest x - ray revealed complete collapse in the left lung . considering the residual surgical time to be relatively long the operation proceeded after confirming the breathing sound on auscultation and improvement in abga . in conclusion , anesthesiologists should always be aware of the incidence of respiratory complications during a laparoscopy , and they should undergo anesthetic management not only of the extent of gas pressuring pressure , duration of surgery , or presence of organic damage , but also be on guard against pneumothorax due to a possible anatomical defect .
pneumothorax associated with a pneumoperitonium in laparoscopic surgery is rare but can cause life - threatening complications . 
 a 62-year - old man was scheduled for a laparoscopy - assisted billroth - i gastrectomy under general anesthesia . 
 approximately 70 minutes after insufflating carbon dioxide into the intraabdominal cavity at a pressure of 12 mmhg , the peak inspiratory pressure increased , while the oxygen saturation decreased . 
 the pneumothorax of the left lung was evident on the intraoperative chest radiograph . 
 the pneumothorax improved after inserting a catheter into the affected area . 
 the cause of the pneumothorax was unknown but an anatomical defect is believed responsible . 
 this report shows that pneumothorax developed under an intraabdominal pressure in the conventional safety range . 
 careful monitoring and immediate treatment is necessary to prevent the condition from worsening .