These findings led to the diagnosis of CTEPH. Because thrombi were found in the 2nd branch levels of the right pulmonary artery, the patient was considered eligible for BPA treatment. Four BPA sessions for 8 branches of the right pulmonary artery were performed by interventional cardiologists after the patient received proper informed consent in our institution. The PAP decreased through those BPA sessions, from 89/25(46) mm Hg to 53/17(29) mm Hg (Table 1).
Preoperative arterial blood gas analysis showed moderate impairment in oxygenation, with a partial oxygen tension (PaO2) of 60.2 mm Hg, partial carbon dioxide tension (PaCO2) of 31.9 mm Hg, and pH of 7.42 in ambient air.
To the patient and his family, we explained the possibility of intraoperative right ventricular dysfunction following PAP surge, mechanical ventilation, and the potential necessity of initiating mechanical circulatory support (i.e., extracorporeal membrane oxygenation) for lifesaving purposes. They accepted these risks, and the TKA was scheduled. The patient strongly refused pulmonary artery catheter (PAC) placement due to a previous failure with PAC insertion. We therefore chose systemic invasive blood pressure (IBP) and central venous pressure (CVP) except for PAP for the invasive hemodynamics monitoring. We arranged for cardiac surgeons to be standby in case ECMO initiation was required at any time during the operation. Warfarin was discontinued preoperatively, and intravenous heparin was administered in order to maintain the activated partial thromboplastin time (APTT) at 50 seconds for 7 days. Eight hours before the operation the heparin was discontinued.
We selected combined spinal and epidural anesthesia with isobaric 0.5% bupivacaine for spinal anesthesia and continuous 0.2% ropivacaine for epidural anesthesia, since the value of APTT returned to the normal range on the morning of the operation day. After central venous catheter insertion, epidural and spinal anesthesia was performed. The epidural catheter was placed from the Th11/Th12 intervertebral space, and then 3 mL of isobaric 0.5% bupivacaine was injected intrathecally from the L3/L4 intervertebral space as spinal anesthesia. Analgesia level was below the Th5 bilaterally. Low doses of continuously infused norepinephrine (0.05 μg/kg/min) and phenylephrine (0.1 μg/kg/min) were administered to maintain the systolic IBP in a range of 100 to 120 mm Hg. Oxygen was administered at 3 L/min during the operation to prevent hypoxia and increase of pulmonary vascular resistance. The tourniquet was deflated in 20 mm Hg steps to minimize hemodynamic changes. Continuous monitoring of both IBP and CVP showed minimal change throughout the operation. The operation time was 2 hours and 15 minutes and the total amount of bleeding was 340 g. With continuous epidural analgesia of 0.2% ropivacaine, no postoperative pain was observed. The epidural catheter was removed on the day after the operation, and continuous intravenous heparin was resumed 5 hours later. The patient was discharged on the 46th day after the operation without complications.
Two years after the first operation, he developed severe left knee osteoarthritis. Unicompartment knee arthroplasty (UKA) was scheduled. A right heart catheterization study was performed as a preoperative evaluation, and revealed nearly the same range of mean PAP (30 mm Hg) as 2 years before (Table 1). This time, the operation was scheduled without additional BPA. Based on our experience of intraoperative hemodynamic stability and adequate analgesia during the first operation, we selected spinal anesthesia only, without continuous CVP monitoring. Heparin was also administered to maintain an APTT value of 50 seconds for 7 days, and discontinued 8 hours before the operation.
A dose of 2.6 mL of isobaric 0.5% bupivacaine was injected intrathecally from the L4/L5 intervertebral space, and analgesia level was below the Th12 bilaterally. Oxygen was administered at 3 L/min during the operation. The systolic IBP was kept around 100 mm Hg throughout the operation without need of phenylephrine or other vasopressor infusion. This time, the surgeon willingly agreed not to use a tourniquet, since we emphasized the likelihood of a change in RV preload upon tourniquet deflation. The operation time was 1 hour and 40 minutes and the estimated blood loss was 170 g. Continuous infusion of fentanyl (25 μg/h) was used for postoperative pain. He was discharged on the 24th day after the operation without complications.
CTEPH is a class of PH characterized by chronic obstruction of large pulmonary arteries due to the formation of organized thrombi. CTEPH is treated with specific strategies distinct from those applied for other types of PH.[1,2] The only established and potentially curative treatment for CTEPH is PEA, but patients ineligible for PEA are treated with pulmonary hypertension-specific drugs or with BPA.[7,8] BPA, first performed in 1983 for pediatric patients, has recently emerged as a primary and adjunctive treatment for CTEPH patients at expert centers. BPA is accompanied by the potential risk of reperfusion pulmonary edema and lung injury. Recent advancement of BPA procedure shows improvement of its safety and effectiveness. The BPA outcome from a multicenter registry in Japan with a total of 308 patients was recently reported; although the complication rates remained high, the overall survival was comparable to that by PEA. Therefore, it may be an important therapeutic option for patients with CTEPH, especially those ineligible for PEA. The prognosis of CTEPH is poor if untreated, especially in patients whose mean PAP exceeds 30 mm Hg. The degree of PH is the most important factor to determine whether a patient can accept a noncardiac surgery. In this case, the mean PAP was reduced to 29 mm Hg after the BPA treatments, and we assessed that the patient could tolerate the anesthesia and operation.
PH is a serious risk factor for perioperative complications. Patients with PH undergoing noncardiac surgery are more likely to develop postoperative right heart failure, hemodynamic instability, sepsis, and respiratory failure, and the mortality rate of PH is significantly high. Various factors, such as mechanical ventilation, pain, hypoxia, acidosis, hypercapnia, and air or fat emboli, can lead to pulmonary vasoconstriction and elevated pulmonary arterial pressure, which potentially results in fatal PH crisis (defined as a PAP equal to or greater than systemic arterial pressure) and subsequent right ventricular dysfunction. Preventing PH crisis is thus the key to successful perioperative management of patients with PH.
In this case, we took all conceivable measures to prevent an increase in PAP. To achieve maximal analgesia, in both operations we chose conventional and familiar neuraxial anesthesia: combined spinal and epidural anesthesia for the first, and spinal anesthesia for the second. Because mechanical ventilation potentially increases pulmonary arterial resistance, we did not choose general anesthesia. Another option was peripheral nerve block—for example, combined sciatic nerve block and continuous femoral nerve block but in our institution it was not common practice at that time. The choice of epidural anesthesia for a CTEPH patient involved a risk, since there was the possibility of intraoperative ECMO initiation that would require anticoagulant therapy. We explained the patient both advantage and disadvantage of epidural anesthesia in usage of anticoagulant drug, and combined spinal and epidural anesthesia was chosen. In both operations, oxygen was administered in order to avoid hypoxia, which would increase PAP.
Continuous PAP monitoring with PAC might have provided useful information, especially under general anesthesia. However, we considered that PAP monitored by PAC would not necessarily reflect PAP accurately in CTEPH patients, because this monitoring is dependent on the placement of the PAC tip. In addition, the patient refused even after we emphasized the importance of the monitoring, because he was strongly concerned about the possible complications of PAC. It could be substitutable with measuring central venous oxygen saturation (ScvO2).
This is the first report of the anesthetic management of a patient with CTEPH, after improving his PH with BPA. BPA could be a preoperative interventional option to minimize the perioperative risks of CTEPH patients.
Conceptualization: Nobuko Ito
Data curation: Kenji Watanabe, Taro Kariya, Takuya Ohata
Investigation: Kenji Watanabe, Taro Kariya.
Writing – original draft: Kenji Watanabe.
Writing – review & editing: Nobuko Ito, Taro Kariya, Hiroshi Inui, Yoshitsugu Yamada.
Nobuko Ito orcid: 0000-0001-9581-3925.
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Keywords:Copyright © 2019 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.
balloon pulmonary angioplasty; chronic thromboembolic pulmonary hypertension; pulmonary hypertension