A 71-year-old, 67-kg, 175-cm, otherwise healthy man was scheduled to undergo TURis for benign prostatic hyperplasia. No premedication was administered. Standard monitoring showed no abnormalities in vital signs except for high blood pressure (170/88 mmHg). Spinal anesthesia using 13 mg of 0.5% hyperbaric bupivacaine was administered. After the loss of cold sensation was reached to the level of T4, he was placed in the lithotomy position. Bicarbonate Ringer’s solution (BICANATE®, Otsuka Pharmaceutical Co., Ltd., Tokyo, Japan) containing 130 Na+, 4 K+, 2 Mg2+, 3 Ca2+, 109 Cl−, 28 HCO3−, and 4 citrate (mEq/L) was administered at the rate of 200 mL/h. TUR-P was performed using a bipolar high-frequency generator (Erbe VIO-3, AMCO Inc., Tokyo, Japan) and a 26-Fr continuous-flow bipolar resectoscope (OES Pro, Olympus Medical Systems Corp., Tokyo, Japan) under irrigation with normal saline that was hung approximately 100 cm above the patient. ECG showed ST-segment depression 30 min after the surgery began, and the patient lost consciousness and responded slightly to only strong stimuli such as pressure over the sternum. This was accompanied by upper airway obstruction and development of hypoxia, and oxygenation was initiated through a face mask. The patient was not intubated due to maintaining spontaneous breathing and acceptable hypoxia, keeping around 90% of SpO2 under the room air. Since venous blood gas sampling showed hypoglycemia, a total of 14 g of glucose was administered. However, his consciousness did not recover. Approximately, at the same time, a gradual decrease in blood pressure was noted, which was not responsive to continuous phenylephrine administration. The height of spinal anesthesia was comparable to that before the surgery. The rapid absorption of the irrigation solution and significant bleeding were suspected. The accumulated amount of normal saline irrigated during surgery was assumed to be up to 26 L. The venous blood test showed acidosis, hyperchloremia, and anemia as well. After discussing the situation with the surgeons, we recommended reducing perfusion pressure and operation time. Total blood loss and urine output could not be measured because of the nature of surgery. Since hypotension and consciousness disturbance persisted after the operation, an arterial line was placed in the radial artery. Transthoracic echocardiogram (TTE) revealed no evidence of heart failure. Immediately after the administration of 120 mL of 8.4% sodium bicarbonate, the state of consciousness improved considerably, followed by restoration of blood pressure (134/57 mmHg) and normalization of the ST segment in ECG. After confirming an improvement in acidosis, 10 mg of furosemide was administered to ameliorate fluid overload. Chest X-ray imaging did not show significant congestion in the lung fields. The patient was transferred to the high care unit, and 560 mL of red blood cells were transfused. On postoperative day 4, the serum chloride level had improved to 108 mmol/L, and the patient was discharged.