杜卜勒超音波在脊髓損傷病患之神經性膀胱功能障礙的應用

研究目的：分析脊髓損傷病人的阻塞性腎病變影響腎臟阻力指數的表現為何；如果用腎臟阻力指數異常大於0.7是否可以作為診斷的標準。另外追蹤病人的腎臟功能（有效腎臟血漿流速，ERPF）之變化，分析腎臟阻力指數和腎臟有效血漿流速變化之相關性，看看腎臟阻力指數是否可以預測病人未來的腎臟功能變化，以瞭解腎臟阻力指數在脊髓損傷病患的整體臨床運用價值。研究方法：51位脊髓損傷病患合併有神經性膀胱功能障礙（平均年齡38.8±14.0歲，38位男性，13位女性）接受腎臟杜卜勒超音波檢查評估兩側水腎狀況和測量腎臟阻力指數，然後安排腎臟核醫掃描來瞭解腎臟功能和腎臟排泄的狀況。先將腎臟分為正常組和阻塞性腎病變組，然後用Student’s t test來看兩組的腎臟阻力指數是否有差異，並且評估腎臟阻力指數0.7是否可以作為診斷阻塞性腎病變的臨界點。之後有19位病人繼續接受腎臟核醫掃描檢查追蹤腎臟功能，依據腎臟阻力指數先把病人的腎臟分成兩組。第一組是正常組，腎臟阻力指數小於或等於0.7，第二組病人的腎臟阻力指數異常大於0.7，接著分析兩組之間有效腎臟血漿流速的變化量是否有差異。結果：正常組的71個腎臟，其腎臟阻力指數平均為0.58±0.07，阻塞性腎病變組的28個腎臟，其腎臟阻力指數平均為0.65±0.08；兩組之間的腎臟阻力指數有統計學上的明顯差異（P值小於0.001）。但是用腎臟阻力指數大於0.7來診斷阻塞性腎病變，其敏感度只有39％，利用接受操作特徵曲線（ROC curve）計算其準確度達0.72。後續追蹤腎臟功能的研究中，總共有38個腎臟，第一組腎臟阻力指數正常的有28個，第二組指數異常的有10個。我們利用單變量廣義估計方程式來分析，發現腎臟阻力指數異常會影響到腎臟功能的變化（P值＝0.01）。腎臟阻力指數大於0.7的第二組，有效腎臟血漿流速會明顯的下降，平均下降為60.33毫升/分鐘（標準誤＝23.26毫升/分鐘）。結論：脊髓損傷併有阻塞性腎病變的患者，腎臟阻力指數會有明顯的上升。但是脊髓損傷的神經性膀胱功能障礙，所造成的是泌尿系統之慢性不完全的阻塞，所以腎臟阻力指數大於0.7並無法用來早期診斷這類病患的阻塞性腎病變。後續腎臟功能的追蹤研究，則發現腎臟阻力指數異常超過0.7，可以用來預測脊髓損傷病患未來的腎臟功能惡化。所以建議對脊髓損傷病患的例行泌尿系統檢查可以使用杜卜勒超音波，計算腎臟阻力指數以瞭解其嚴重程度及預後。

Purpose: To assess renal resistive index (RRI) changes in spinal cord injured (SCI) patients with obstructive uropathy and to determine if RRI＞0.7 is useful in identifying such patients. And study the relationship between RRI and deterioration of renal function in patients with SCI.Materials and methods: A convenience sample of fifty-one SCI patients with neuropathic bladder dysfunction (mean age, 38.8 ± 14.0 yrs; 38 men, 13 women) Ultrasonic examination to assess the degree of hydronephrosis, Doppler sonography to calculate RRIs, and radioisotopic renography to assess renal function and to determine excretory curves. Kidneys were assigned to control or obstructive uropathy groups, and RRIs were compared for statistical significance (Student’s t test) and to assess whether RRI = 0.7 is a distinguishing criterion. Nineteen patients who underwent follow-up with radioisotopic renography were included in the second study. The median patient age was 50 years (IQR, 35 – 57 years) and the duration of time since injury was 4.7 years (IQR, 1.3 – 9.2 years). Using Doppler ultrasound, kidneys of the patients were divided into groups based on baseline RRI: normal RRI (£ 0.7) or Group I (n = 28) and abnormal RRI (> 0.7) or Group II (n =10) and were followed up with radioisotopic renography one or more years later. The change in effective renal plasma flow (ERPF) was analyzed. Results: Average RRIs were 0.58 ± 0.07 in the control group (71 kidneys) and 0.65 ± 0.08 in the uropathy group (28 kidneys) (P < .001). Sensitivity of using RI＞0.7 to identify patients with obstructive uropathy was 39%. The C statistic of the receiver operating characteristic (ROC) curve was 0.72.The follow-up study included 38 kidneys (two for each patient) were stratified by initial RRI with 28 in Group I and 10 in Group II. The result of univariate generalized estimation equation (GEE) analysis for the factors affecting the change in ERPF indicated that the high RRI value (RRI > 0.7) negative correlated with the change in ERPF. The ERPF value in Group II was significantly decreased (P = 0.01); the average decrease in ERPF in Group II patients was 60.33 ml/min (SE = 23.26).Conclusions: RRI increase in SCI patients with obstructive uropathy. In SCI patients, urinary findings fit the chronic partial obstruction pattern. RRI＞0.7 is a poor indicator of obstructive uropathy in such patients. The follow-up study showed that RRI > 0.7 is a risk factor for future deterioration in renal function in patients with SCI. Thus, Doppler ultrasonography to assess the RRI of SCI patients with neurogenic bladder dysfunction is recommended.