小林 大樹¹, 末光 浩太郎², 名波 正義³

Hiroki KOBAYASHI¹, Kotaro SUEMITSU², Masayoshi NANAMI³

¹関西労災病院中央検査部, ²関西労災病院内科（腎臓）, ³兵庫医科大学内科学 腎・透析科

¹Central Clinical Laboratory, Kansai Rosai Hospital, ²Department of Internal Medicine, Division of Kidney and Dialysis, Kansai Rosai Hospital, ³Division of Kidney and Dialysis, Department of Internal Medicine, Hyogo College of Medicine

キーワード : complication, vascular access, cannulation inability, aneurysm, infectious lesion

超音波診断装置を用いたバスキュラーアクセス（vascular access: VA）の評価は，様々な合併症の診断において活用できる．今回は，代表的な穿刺困難，瘤，感染について述べる．透析における日常の穿刺は，患者と穿刺者との信頼関係をつなぐ重要な業務である．穿刺困難に対しては原因を超音波検査で特定し，その症例に合った対処が必要になる．大部分は穿刺部位に問題があり，血管内腔の狭小化や蛇行，静脈弁の存在，血管走行が深いなどが原因で針先が血管内に留置されない場合がある．このような症例では，穿刺部位を変更するだけで対応できることもある．瘤においては，破裂のリスクを評価することが重要である．数日間で急速に増大傾向があるものや，瘤の表面に光沢を伴う症例は注意が必要である．超音波検査では，瘤の発生原因となる瘤前後の狭窄病変や瘤の大きさ，瘤の壁厚，壁の性状を観察する．これにより，経時的な変化を捉えることができる．VAの感染は，命に関わる重篤な合併症である．超音波検査では，発赤部に一致して限局した低エコー域を認める．ただし，画像診断は補助的診断であり，発熱などの臨床症状や炎症反応などの血液データ，血液培養検査も含めて総合的に判断する．VAの合併症に対しては病態を把握した上で，超音波診断装置を用いて多角的に情報を収集していく．なぜそのような臨床症状が出現するのかを考えながら検査を進めていくことが重要である．

Ultrasound (US) vascular imaging is essential to ensure successful management and maintenance of hemodialysis (HD) vascular access (VA). It is also a valuable adjunct in assessing certain VA-related complications as below. 1) Cannulation Inability: Adequate implementation of repeatable and safe cannulation of VA is required both in the clinical practice of HD treatment and for establishment of the patient-practitioner relationship. US imaging facilitates identification of the cause of inaccessibility mainly attributable to vascular structural obstructions in the cannulation segment. It also enables us to provide a resolvable approach by identifying an alternative cannulable segment. 2) Aneurysm/Pseudoaneurysm Formation: Prompt detection of aneurysmal instability and impending rupture is crucial for the potential urgent procedure. Both rapid aneurysmal enlargement in the short term and overstretched shiny appearance of skin overlying the aneurysm are the primary predictors indicating the occurrence of these serious conditions. US imaging elucidates sequential morphological alteration of the aneurysm such as its expansion and contour transformation. Additionally, it is useful for identifying the fundamental vascular stenosis in aneurysmal formation. 3) Infectious Lesion: Infectious VA-related complications remain a significant cause of morbidity and mortality in HD patients. A combined approach based on both identification of the infectious lesion and detection of the systemic inflammatory reaction with infectious findings is indispensable for the precise diagnosis of VA infection. The existence of a localized hypoechoic area detected by US consistent with the erythema is a reasonable and supportable manifestation of the infectious lesion. In conclusion, recent advances in comprehensive management of VA-related complications have led to an increased utilization of US imaging as an adjunctive assessment tool. In the diagnostic process employing the herein-described advantageous US approach, careful ascertainment of the compatibility between imaged manifestations and clinical symptoms ensures accurate comprehension of the pathophysiology.