A 4-year-old boy( height ,100 centimeters;weight,16 kilograms)was hit in the chest by a car.He was conscious and complained of chest tightness.Upon arrival to the local hospital after 18 minutes, he was semiconscious and cyanotic, and breath sounds were not heard in the right hemithorax, and his vital signs were unstable:heart rate(HR) of 162 beats per minute(bpm), blood pressure(Bp) of 102/56 mm Hg, respiratory rate(RR) of 32 times per minute, and oxygen saturation(SPO2) of 70%.30 milligrams of propofol intravenously for sedation, and then emergency endotracheal tube above the carina was performed.Chest computerized tomography (CT) showed right pneumothorax with lung compression of 90%, and the left clavicle was fractured(Figure 1). A chest tube was positioned in the right thoracic cavity and a breathing balloon was used for ventilation, and then his vital signs were as follow:HR of 155bpm, Bp of 97/50 mm Hg,RR of 22 times per minute, and SPO2 of 98%. 24 minutes later, he was admitted to the emergency department of our hospital for further treatment. The results of blood gas analysis were as follows:pH, 7.12; carbon dioxide partial pressure(PaCO2), 76 mm Hg;oxygen partial pressure(PaO2), 68 mm Hg. Bronchoscopy indicated that the right middle lobe bronchus was ruptured .Transthoracic echocardiography ruled out associated blunt cardiac injury. Emergency exploratory thoracotomy and the right middle or right middle and lower lobectomy were planned. The patient went into sudden cardiac arrest after being sent to the operating room (SPO2,76%;End-tidal carbon dioxide partial pressure (PetCO2),46mmHg). After 12 minutes of cardiopulmonary resuscitation he regained his spontaneous heart rhythm. He didn't regain consciousness. Mainstem intubation of the left bronchus under direct fiberoptic guidance to ventilate the left lung.Pressure control ventilation(fraction of inspiration O2 was 100%, peak pressure was 32cmH2O,tidal volume was 45milliliters),HR of 145bpm, Bp of 92/48 mm Hg(0.05µg/kg/min norepinephrine),RR of 20 times per minute, and SPO2 of 70%. Blood gas analysis results at this time were as follows:pH, 6.87; PaCO2, 114 mm Hg; PaO2, 46 mm Hg; plasma lactic acid (Lac), 6.7 mmol/L; K+,3.2 mmol/L;Hemoglobin 7.3g/dl;Ca++ 1.21mmol/L.Sudden cardiac arrest occurred due to severe respiratory acidosis, so we decided to initiate V-V ECMO.Our hospital is an adult ECMO center, and it is 300 km away from our nearest pediatric ECMO center, approximately a 3.5-hour drive. The child was at death's door, therefore, we decided to use the smaller adult ECMO tubes. ECMO was initiated via percutaneous in the left femoral vein and incision in the right internal jugular vein (MAQUET 2050, Cardiopulmonary GmbH BE-PLS, Germany; the left femoral vein:15Fr/5mm single-stage drainage cannula,MAQUET, Germany; the right internal jugular vein:14Fr/ZX 4.7 return cannula, Changzhou Kangxin Medical Equipment Co., Ltd., China). The blood flow was 1.7 L/min, sweep gas was 1.5 L/min, FiO2 was 100%.Cardiac arrest occurred again after ECMO, so we gave him cardiopulmonary resuscitation immediately. Blood gas analysis results at this time were as follows:pH, 6.84; PaCO2, 72 mm Hg; PaO2, 61 mm Hg; Lac, 9.7 mmol/L; K+, 9.8 mmol/L;Hemoglobin 7.3g/dl;Ca++ 1.21mmol/L. Soda bicarb (5%, 32ml), insulin(2 U) added to glucose injection (10%,100 ml) ,and calcium chloride injection (3%, 0.1 g) were given at once.Spontaneous sinus rhythm was restored after 18 minutes. An exploratory thoracotomy was performed successfully, the root of the right middle lobe bronchus was found to be ruptured (Figure 2), and a branch of the right middle lobe artery was ruptured. Right middle lobectomy and right middle bronchoplasty were performed. He was admitted to the intensive care unit(ICU) after the operation. Mechanical ventilation and ECMO was continued, we adjusted the ventilator parameters: FiO2 was set at 30%, positive end expiratory pressure (PEEP) was set at 10 cmH2O, the respiratory rate was set at 12 times/minute and the tidal volume was set at 6 mL/kg. Oxygen saturation was between 98% and 100%. Along with mild hypothermia for brain protection(34-36 celsius degree for 30 hours), piperacillin sodium and tazobactam injection for the prevention of infection, methylprednisolone injection(16mg q12h) to reduce pulmonary exudation, and norepinephrine 0.15 µg/kg/min to maintain blood pressure.On postoperative day 2, he became conscious and was able to act on command. Due to the traumatic wet lung on the left and secondary pulmonary infection, ECMO was withdrawn on the 6th day after the operation, with a total ECMO time of 137 hours. On postoperative day 11, mechanical ventilation was withdrawn. On postoperative day 12, chest CT showed a mass of high-density shadow in the upper lobe of the left lung with cavitation, considered a large traumatic pseudocyst (Figure 3). He left the ICU on postoperative day 16. He was discharged from the hospital on postoperative day31 without neurological deficit. He is able to communicate and play normally.The timeline of the treatment process is shown in Figure 4.