Anesthetic management of antiphospholipid syndrome patients who underwent cardiac surgery: three cases report
A 23-year-old man (192 cm, 106.4 kg) presented to the authors for pulmonary thromboembolism and was scheduled for pulmonary artery thrombectomy. He has been diagnosed with APS after the treatment of deep vein thrombosis in his right leg at another hospital four years earlier, and he had been prescribed an anticoagulant medicine. Two weeks before the patient's hospital admission, he stopped taking the medication at his discretion. Tenderness, edema, and skin ulcers occurred in both his lower extremities. During his hospital stay, the patient developed dyspnea, and pulmonary thromboembolism was diagnosed in both his descending pulmonary arteries and lower lobe segmental and subsegmental arteries via echocardiography and chest computed tomography. The result of the lung perfusion scan that was performed was also suitable for pulmonary thromboembolism. The preoperative diluted Russell's viper venom time (dRVVT) result was 112.80 s (reference: 24-37.5 s), and the silica clotting time (SCT) was prolonged to 185.6 s (reference: 23.4-39.2 s). Arterial oxygen tension was 70 mmHg under room air. The mixing test was not corrected, and the result was 112.80 s with the patient plasma, and 73.3 s with the mixed plasma. The patient was thus diagnosed with lupus anticoagulant (LA). The anticardiolipin antibodies (ACAs) IgG, and IgM were positive, the antithrombin III was 85% of the normal level, the protein C was reduced to 66%, and the protein S was reduced to 57%. Enoxaparine 120 mg was injected via the subcutaneous tissue twice a day and prednisolone was administered during the preoperative period. An abnormal coagulation profile was observed; prothrombin time/international normalized ratio (PT/INR) was 1.9, prothrombin time (PT) was 22.3 s and activated partial thromboplastin time (aPTT) was 79.1 s. Preoperative estimated pulmonary arterial systolic pressure (PASP) was 76 mmHg.\nRadial artery catheterization was performed, and midazolam (13 mg), sufentanil (150 µg), and vecuronium (10 mg) were injected for induction of anesthesia. The routine monitoring devices for cardiac surgery and intravenous anesthetics were used for maintenance of anesthesia. Initial point-of-care testing (POCT) results were the following: arterial oxygen tension was 201 mmHg under a 50% fraction of inspired oxygen (FiO2), and plasma hematocrit was 54%. The activated coagulation time (ACT) was 165 s after induction and 951 s after injection of 336 mg of heparin to begin CPB. CPB was started after insertion of the cannulas into the aorta, superior vena cava, and inferior vena cava. After the temperature was lowered to 20℃, pulmonary thrombectomy and endarterectomy were performed, following which intermittent total cardiopulmonary bypass using aortic-cross-clamp was conducted to clear the operating field. Forty minutes after the administration of heparin, the ACT was checked again and found to be 627 s. Generally, such a result would be considered acceptable for a CPB operation, but concerns about the occurrence of catastrophic APS in this case, prompted the empirical administration of 100 mg of heparin via injection. The ACT was again measured 5 min after the injection and was found to be 1200 s. After 3 hours, the ACT was found to be 629 s. An additional 80 mg of heparin was thus administered, and the ACT was found to be 1001 s 5 min after that injection. It was decided that protamine would not be administered due to worries about the occurrence of postoperative thrombotic complications. Forty minutes after the last heparin injection, weaning from CPB was successfully performed. The total injected dose of heparin was 516 mg, and the total CPB time was 248 min. At the end of the surgery, POCT was again performed. Arterial oxygen tension was 332 mmHg under 50% FiO2 and plasma hematocrit was 42%. The estimated blood loss (EBL) during surgery was 1,000 ml and urine output was 1,100 ml. 1,500 ml of crystalloid and 1,400 ml of colloid were infused during surgery. No transfusion was performed during the surgery.\nFollowing the procedure the patient was transferred to the intensive care unit (ICU) without experiencing significant bleeding. The immediate postoperative PT/INR was 1.63 and aPTT was over 180 s. The goal of the postoperative anticoagulation therapy was PT/INR 3.0 with intravenous heparin infusion during the NPO period and with oral warfarin after that. PASP was not normalized after the surgery; postoperative PASP was 74 mmHg. The patient was discharged 12 days after surgery without specific complications.