Paradoxical air embolism due to electrosurgical vaporization during hysteroscopic myomectomy

Corresponding author: Keon-Sik Kim, M.D., Department of Anesthesiology and Pain Medicine, Kyung Hee Medical Center, 1, Hoegi-dong, Dongdaemun-gu, Seoul 130-702, Korea. Tel: 82-2-958-8589, Fax: 82-2-958-8580, E-mail: [email protected] This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. CC Air emboli can arterialize and result in paradoxical air embolism (PAE). In most cases there is a right to left shunt, and for this to occur during a hysteroscopic surgery is extremely rare. This case report describes a PAE found in the left heart during hysteroscopic myomectomy without an anatomical right to left shunt. A 29­yr­old woman (height 170 cm, weight 62 kg, American Society of Anesthesiologists I) was seen at our gynecologic clinic due to a known uterine myoma. She had no specific medical history, and had given birth to a preterm baby of 24 weeks by cesarean section under general anesthesia 6 months earlier. There were no abnormal findings in the preoperative examination and she had no risk factors for cardiac or pulmonary disease. For maintenance during the operation, O2 2.0 L/min, N2O 2.0 L/min, and desflurane 4.0-6.0 vol% was used. Though at the beginning of the surgery vital signs were stable, after 15 min systolic and diastolic blood pressure decreased to 80-100 mmHg, and 40-60 mmHg respectively. Arterial blood gas analysis (ABGA) revealed that the pH was 7.384, PaO2 271.9 mmHg, PaCO2 29.8 mmHg, hemoglobin 6.9 g/ dl, Hct 20%. As systolic blood pressure continued to drop to 8090 mmHg, diastolic blood pressure to 40-50 mmHg, and mean arterial pressure (MAP) to 60-65 mmHg, 10 mg of ephedrine was administered, while 2 units of packed RBC transfusion was initiated. In order to continue measuring blood pressure and arterial blood gas, a 20 gauge catheter was inserted in the left radial artery. The results of the ABGA after the radial artery cannulation were pH 7.336, PaO2 291.1 mmHg, PaCO2 35.9 mmHg, and PETCO2 25 mmHg. Though PETCO2 decreased only slightly, the decreasing blood pressure and signs of increase in PaCO2 gave rise to suspicions of pulmonary embolism, so N2O was discontinued and oxygen and medical air were both maintained at 2.0 L/min. Ninety minutes after the beginning of the surgery, the MAP suddenly dropped to 60 mmHg and the PETCO2 could not be detected (having decreased to 0 mmHg). The ABGA initiated at this point and showed pH 7.149, PaO2 65.4 mmHg, and PaCO2 35.9 mmHg. Because the changes in hemodynamics coupled with the results of the ABGA lead to suspicions of pulmonary embolism, O2 supply was kept at 100% and positive pressure ventilation was initiated. Transthoracic echocardiography (TTE) was used to confirm an air embolism in the left heart (Fig. 1). The lung perfusion scan performed after the surgery revealed multiple non­matched small non­