Here, we report a rare case in which the inlet pressure of the oxygenator increased three times in two operations, even though two different types of oxygenators were used. A 45-year-old man underwent mitral valve repair owing to posterior cusp (P2) prolapse. Immediately after median sternotomy, the patient went into anaphylactic shock. We immediately started cardio-pulmonary bypass. The inlet pressure in company A's oxygenator increased, and the oxygenator was immediately replaced with the same type of oxygenator. However, the same occurred, and the oxygenator was exchanged for one made by company B. Thereafter, the operation was completed without further oxygenator problems.Fifty-five days after the initial surgery, a second operation was performed to repair a pseudoaneurysm at the root vent cannulation site. After induction of general anesthesia, the patient went into anaphylactic shock, as before, but circulation was maintained. Cardio-pulmonary bypass was started using company B's oxygenator, as it gave no problems at the previous surgery. However, it had to be exchanged owing to inlet pressure elevation. Thereafter, cardio-pulmonary bypass was maintained without pressure elevation, and the operation was completed. The reasons for the inlet pressure elevations are unclear.

The patient is a 66-year-old woman. She had been taking steroids for some years for rheumatoid arthritis and had been using crutches for some years because of multiple joint deformities. She presented herself to an orthopedic clinic for right upper extremity numbness and was diagnosed with cervical spondylosis and was kept under observation. However, 7 days later, a pulsatile mass on her right upper arm was found and she was referred to our hospital. Contrast-enhanced CT revealed a right brachial artery aneurysm (19×17×16 mm）, and the numbness was considered to be a symptom of nerve compression caused by the aneurysm. Since the cause of the brachial artery aneurysm was long-term inappropriate use of crutches, we confirmed that the patient would not use crutches and would use other assistive devices after the surgery, and then performed aneurysm resection and direct anastomosis under general anesthesia. Aneurysms of the upper extremities are rare and are often traumatic or iatrogenic pseudoaneurysms, and surgery is recommended because they can cause complications such as embolism, nerve compression, and rupture. In revascularization in cases where the aneurysm is caused by crutches, it is necessary to consider the risk of recurrence. In our case, we were able to perform direct anastomosis by switching the walking aid from crutches to Lofstrand clutches.