Acute Pulmonary Embolism NEJM 2008:358:1037-52

疫学と病態 合衆国では年間３０万人が死亡 肺塞栓の患者の８割に下肢静脈血栓あり 下肢静脈血栓症の５割に肺塞栓合併 残りの２割にもあると考えられる 下肢静脈血栓症の５割に肺塞栓合併 気管支動脈があるので、肺梗塞にはならない 通常死因は右心不全 3ヵ月後までの死亡率は15～18%

危険因子 整形外科（膝、股関節）手術、悪性腫瘍手術 外傷、脊髄損傷 長期臥床の内科系入院患者 長時間の座位（運転、旅行、コンピュータ） 妊娠・産褥期 更年期症状に対するホルモン療法 加齢

臨床症状:スコアで判断 下肢静脈血栓症：痛み、熱感、腫脹 呼吸困難、胸痛、血痰 非特異的：咳、動悸、喘鳴、頻呼吸、頻脈 失神、突然の低血圧、低酸素血症 身体所見 頸静脈の拡張、P2の亢進、右室隆起 身体所見スコア：Canadian or 改訂Geneva

Low:1.3% Moderate:16.2% High:37.5% Low&D-dimer(-)でPEを完全否定(99.5%)

3点以下の8% 4-10点の28% 11点以上の74% がPE

4点以下の10% 5-8点の38% 9点以上の81% がPE

検査と診断アルゴリズム ECG：感度・特異度ともに不十分 胸部X線：役立たない 血液ガスで低酸素血症がないことも D-dimer：感度はいいが非特異的 臨床スコアが低くてD-dimer陰性→画像不要 臨床スコアが高ければD-dimer不要ですぐ画像 他の補助的な検査 トロポニン:massive PEで上昇 BNP:右室拡張で上昇

画像診断 シンチグラム CT arteriography MRI 肺血管造影 代用画像診断（下肢静脈血栓症の検出） 超音波 CT or MRI venography

CT arteriograpy 特にmultidetector CTは有用 シンチと比べて：早い＆血管以外の構造もわかる＆静脈造影(CT venography)もできる Main, lobar, segmental arteryの塞栓検出の感度、特異度ともに良好 造影剤使用：腎障害患者で使いにくい multidetector CTと超音波による下肢静脈の検索で、治療方針が決定できる 特異性が高いので、陽性なら治療開始

シンチ: Ventilation-Perfusion scan 感度良好：陰性は肺塞栓を安全に除外 臨床的に疑わしいのにシンチが明確でない場合→CT angioを含めて他の診断を進める 臨床的に可能性が低くてD-dimerも陰性でシンチが明確でなかったら検索は中止

その他の画像診断法 MRI：胸部MRIに引き続き、下肢のMRI venographyも有用と（ただしデータは少ない） 心エコー：補助的に使う 肺血管造影：この総説では言及していない（Additional testingの位置付けか？）

Figure 3. Diagnostic Approach to Suspected Acute Pulmonary Embolism. The use of prediction rules and d-dimer testing may reduce the need for imaging. If the risk of bleeding is deemed to be low, initiation of therapy before a proven diagnosis of pulmonary embolism should be considered.40 At this juncture, the chest radiograph and other specific imaging may already be completed. A ventilation–perfusion (VQ) scan is more likely to yield a diagnosis when there is no associated cardiopulmonary disease. A scan indicating a high probability of pulmonary embolism is confirmatory except when there has been aprior pulmonary embolism, in which case a previous VQ scan may be useful in proving that defects are new.34,36 As with computed tomographic arteriography (CTA), the approach to a nondiagnostic scan includes evaluation of clinical probability as well as consideration of additional testing. Deep venous thrombosis discovered by leg ultrasonography, CT venography, or magnetic resonance venography suggests concomitant pulmonary embolism.36,37 Standard pulmonary arteriography or venography is rarely needed. Adding CT venography to CT arteriography enhances the overall sensitivity for detecting venous thromboembolism,33 although an excellent outcome has beendemonstrated without additional testing when CTA is negative.22 With the use of CTA or CT venography, caution is advised when the creatinine level rises above 1.5 mg per deciliter; the patient’s age relative to the creatinine clearance should be considered.36 ELISA denotes　enzyme-linked immunosorbent assay.

まずは抗凝固療法 低分子ヘパリン or フォンダパリヌクス 肺塞栓が強く疑われれば画像前に開始可 未分画ヘパリン：低コスト vs モニタリング 肺塞栓が強く疑われれば画像前に開始可 同時にワーファリンも開始→INR 2.0～3.0 ヘパリン・フォンダパリヌクス最低5日間継続 ワーファリンによる外来治療は3－6ヶ月あるいはそれ以上必要

その他の治療 下大静脈フィルターの適応と問題点 補液・昇圧剤 線溶療法 抗凝固療法禁忌、十分な抗凝固療法下再発例 問題点；続発性の血栓形成、生命予後は不変 補液・昇圧剤 ショック、右心不全→左心preloadの減少例 線溶療法 適応：心原性ショック例 頭蓋内出血が１－３％に出現

Figure 4. Treatment of Acute Pulmonary Embolism. Low-molecular-weight heparin is preferable to unfractionated heparin in most settings.40 Use of an optional (retrievable) inferior vena caval filter (IVCF) offers the potential for removal when risk factors are deemed transient.63 Although filter placement may be considered in patients with massive embolism in order to prevent additional emboli, this indication has not been studied in prospective, randomized clinical trials. Anticoagulation should be initiated when the risk of bleeding subsides. Although the clearest indication for thrombolytic therapy is hemodynamic instability with cardiogenic shock caused by acute pulmonary embolism, hypotension, particularly if refractory to initial supportive measures (e.g., cautious fluid administration), also merits consideration of this approach. Some clinicians consider right ventricular dysfunction to be an indication for thrombolysis,68,69 but no study has been large enough to prove that thrombolytic therapy reduces mortality in this setting or in the setting of severe hypoxemia and respiratory failure. Each case must be considered individually. Thrombolytic agents with shorter infusion times, such as tissue plasminogen activator (t-PA) (100 mg given intravenously over a period of 2 hours) have been recommended. 40,68,69 Local thrombolytic therapy, catheter embolectomy, or both can be considered in centers with experience with these techniques.40 Potential contraindications for thrombolytic therapy include previous intracranial or ophthalmic surgery or disease, clinically significant active or recent bleeding or risk of bleeding, and recent surgery (within 1 to 2 weeks, depending on the procedure). Consideration of the severity of the pulmonary embolism and the perceived risk of bleeding should contribute to the decision to use thrombolytic therapy. Intracranial abnormalities are generally considered to be absolute