REVIEW ARTICLE J Surg Ultrasound 2016;3:7-12 JSU Journal of Surgical Ultrasound 초음파를이용한투석접근로의평가 중앙대학교의과대학중앙대학교병원외과학교실 박병욱, 김향경 Ultrasonographic Evaluation of Hemodialysis Access Byung Wook Park, Hyangkyoung Kim Department of Surgery, College of Medicine, Chung-Ang University, Seoul, Korea Received May 3, 2016 Revised May 5, 2016 Accepted May 6, 2016 Correspondence to: Hyangkyoung Kim Department of Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, 224-1 Heukseok-dong, Dongjak-gu, Seoul 06973, Korea Tel: +82-2-6299-1564 Fax: +82-2-6298-8351 E-mail: hkkim@cau.ac.kr Maintaining patency of vascular access is of great importance in ensuring adequate dialysis in chronic kidney disease patients, and subsequent complications of access represent a major cause of morbidity, hospitalization, and cost of intervention or surgery. Duplex ultrasound is a key technique currently employed for investigation of access related problems. Its reliability and accuracy is comparable with that of conventional angiography. It is used as a preoperative tool in assessment of arterial and venous anatomy and in making surgical decisions. In the pre-dialysis fistula, it provides information on maturation status and the causes of immaturity if the fistula is not adequate for dialysis. In ongoing access surveillance, it defines the nature, location, and severity of the problem, such as stenosis, pseudoaneurysm, aneurysm, steal syndrome, and venous hypertension, enabling the planning of endovascular or open surgical treatment. Stenosis, the most common problem, can be assessed using PSV (peak systolic velocity), PSV ratio, and volume flow. Keywords: Ultrasound, Hemodialysis access, Maturation, Stenosis 배경 투석환자에서투석접근로의개존은적절한투석및재수술율, 그로인한경제적비용과관련된중요한문제이다.(1) 투석접근로수술시일차실패율 (primary failure) 을낮추고장기개존율을높이기위해서는수술전후계획적인접근이필요한데, 수술전환자혈관상태의정확한평가와수술후접근로의협착및이상의빠른발견을위한적절한감시및치료가도움이된다고알려져있다.(2-4) 적합한혈관을찾기위한수술전평가로는혈관천자및혈액학적질환등에대한자세한병력청취, 기본적인신체진찰에서부터초음파, 혈관조영술, 전산화단층혈 관조영술 (Computed tomography (CT) angiography), 자기공명혈관조영술 (magnetic resonance angiography) 등의방법등이있다. 신체검진을통해원위동맥의맥박, 표재정맥의유무를육안으로관찰하고수장궁 (palmar arch) 의개존여부를알기위해 modified Allen s test를시행할수있다. Modified allen s test는환자가 30초간주먹을쥔다음검사자가요골동맥과척골동맥을동시에눌러서폐색시키고환자가주먹을펴게한다음척골동맥만개통시켰을때손의색깔을관찰하는것이다.(5) 손의색깔이 3-12초사이에돌아오면정상으로판단한다. 육안으로보이지않는혈관의폐색이나협착등의이상을파악하기위해서영상검사를시행할경우수술 Journal of Surgical Ultrasound is an Open Access Journal. All articles are distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright c 2016 by The Korean Surgical Ultrasound Society ISSN 2288-9140
J Surg Ultrasound Vol. 3, No. 1, 2016 성공률을높이고자가혈관을이용한동정맥루수술가능성을높이는데도움이된다.(6) 전통적으로혈관에대한평가는혈관조영술로이루어져왔으나방사선노출의단점이있고, 혈관조영술이나 CT 혈관조영술의경우조영제를사용하므로신대체요법을준비하는환자들에게신장기능을악화시킬가능성이높다. 또한 gadolinium 을이용하여조영증강한 MR 혈관조영술의경우전신섬유화 (systemic fibrosis) 를유발할수있어주의가필요하며비용이많이든다. 이러한이유로최근초음파가투석접근로의평가에일차적으로권유되며, 금식과조영제, 방사선노출없이필요에따라반복적으로시행할수있어매우유용한검사법이다. 수술전초음파로동맥의직경, 동맥경화증여부, 절개부위주위석회화여부, 유출정맥의직경, 폐색여부등을파악할수있다. 첫수술을계획한환자들에서수술전초음파검사를시행할경우 66% 에서협착이나폐색과같은혈관이상을미리발견했다는보고가있다.(7) 수술중초음파는수술전초음파소견을다시한번확인하고절개창의위치와사용할혈관의박리위치결정에사용된다. 특히비만하거나이전투석접근로수술병력이있는환자, 당뇨환자와같은수술이복잡해질가능성이있는환자군에서수술중에많은도움을받을수있다.(7) 수술후투석접근로의사용중에는협착의조기발견으로폐색이발생하기전치료계획을세우는데중요한역할을한다. 투석접근로의폐색에는동반된협착이있을가능성이 80-90% 정도로높으므로폐색이발생한경우에도협착부위를미리파악하여시술이나수술의방법을결정할때도이용된다.(8,9) 표준검사인혈관조영술에비교하였을때동반된협착을평가하는데초음파의정확성은증명되어있다.(10) 본문 투석접근로의평가를위해서는고주파수의선형탐촉자를이용하여검사한다. 삼각흉근구 (deltopectoral groove) 에서부터쇄골아래에위치하는액와정맥과쇄골하정맥이만나는부분까지관찰하기위해서는 8-5 MHz 부채꼴탐촉자를이용하기도한다. 정맥은방온도에민감하여수축할수있으므로정확한검사를위해따뜻한젤을이용하는것이추천되나 (11) 더욱중요한것은충분한젤을발라표 재에위치한정맥이탐촉자로눌리지않도록주의해야한다.(12,13) 1. 수술전초음파수술전초음파의유용성에대하여는다소상반된보고들이있다. Nursal 등은신체검진단독으로시행한경우와수술전초음파를시행한경우를비교하였을때수술후 1일째만져지는진동이나일차개존율의차이가없다고했다.(14) 그러나 Mihmanli 등은수술전진찰만으로수술한경우자가동정맥루수술실패가능성이 25% 인반면초음파를함께검사한경우 6% 로초음파를이용하여수술전초음파로혈관상태를확인할경우자가혈관동정맥루의수술성공율이높아진다고하였다.(6) 수술전신체검진을통하여세운수술계획이초음파를시행하여변경되는경우에대하여시행한연구에서는신체검진소견으로얻을수있는정보가충분하여신체검진만으로수술계획을세울수있는경우에는초음파검사를시행하여도계획이변경될가능성이적다고했다.(15) 따라서신체검진으로충분한정보를얻기어려운경우에초음파를시행할경우가장이득이많다. 수술전초음파로관찰할수있는사항으로는동맥과정맥의형태, 직경, 정맥의확장성, resistive index, 초음파를이용한역동적 Allen s test (dynamic Allen s test), hyperemia response 등이있다. 1) 동맥초음파로동맥을관찰할때에는원위부부터근위부까지내막의모양이울퉁불퉁하지않은지, 벽이두꺼워져있지않은지, 동맥경화반이있는지, 벽이두꺼워져있지않은지횡단면과종단면영상으로관찰한다. 종단면에서최고수축기속도 (peak systolic velocity, PSV) 와파형을관찰한다. 수장궁의개존을알기위해역동적 Allen s test와 reactive hyperemia test를시행할수있다. 동맥의직경은횡단면과종단면으로관찰하여내막에서내막까지의거리를잰다. 동정맥루수술에이용가능한동맥의정확한직경은알려져있지않으나 2 mm 이상일경우적합하다고보고되었다.(4) 요골동맥의정상 PSV값은 40-90 cm/sec 이며삼상파형이보일때혈역학적으로의미있는협착이없다고판단할수있다.(16) 초음파를이용한역동적 Allen s test는초음파탐촉자를첫번째손가락동맥에두고요골동맥을눌렀을때파형 8
Byung Wook Park, Hyangkyoung Kim: Ultrasonographic Evaluation of Hemodialysis Access 을관찰하는것인데혈류의역전이일어나는것이관찰되면손의측부혈행이충분하다는것이고혈류가중단되면측부혈행이충분하지않다는것을알수있다 (Fig. 1).(17) Hyperemia response 는원위부요골동맥에탐촉자를대고 3분간주먹을쥐어허혈상태를만든다음주먹을펴서혈류모양과저항지수 (resistive index) 를관찰하는것이다.(12) 주먹을쥔상태에서는 3상의고저항성파형 (triphasic high resistance waveform) 을보이다가주먹을폈을때단상의저저항성파형 (monophasic low resistance waveform) 을보이면서저항지수가 0.7보다작을때정상소견이다. 저항지수가 0.7 이상일때는수술직후혈류증가가충분히일어나지않을가능성을시사하는소견이다.(11) 2) 정맥정맥은노쪽피부정맥 (cephalic vein), 자쪽피부정맥 (basilica vein), 심부정맥순으로원위부혈관부터쇄골하정맥과내경정맥등관찰가능한중심정맥까지관찰한다. 우선전반적인모양과주행을관찰한후탐촉자로분절별로압박하여보아폐색여부를확인하고벽이두꺼워져있는지, 내강에에코성의물질이차있지는않은지, 연속성 (continuity) 등을관찰한다. 자가동정맥루에이용되는정맥은피부에서 6 mm 이상깊이떨어져있을경우천자에어려움이있으므로피부에서부터의깊이도측정해야한다. 쇄골하정맥근위부의중심정맥은초음파로직접관찰하기에제한점이있으므로호흡에따른 phasicity 의변화가있는지관찰하여간접적으로개존여부를알수 있다. 정맥의직경은하루에도여러번변할수있고방온도에따라서도변할수있어한환자에서도여러가지값을보일수있다. 수술에이용할수있는혈관의정확한직경은알려져있지않으나자가동정맥루수술시전완에위치하는정맥의직경이 2 mm 이하일경우결과가좋지않았다고하며 (18) 2 mm 이상일경우성공할확률이높았으며 (19) 위쪽팔의혈관일경우 3 mm가적당하다고하였다.(13) 인조혈관동정맥루의경우에는압박띠를감았을때정맥의직경이 4 mm 이상이되어야한다고하였다.(4) 정맥의확장성또한개존율에영향을미치는중요한인자로알려져있는데 (11) 2.5 mm보다작은정맥이압박띠를 2분정도감고다시측정하였을때 2.5 mm까지확장되면 2.5 mm 이상의정맥을이용한수술과결과가비슷하다고하였고 (20) 지압대를감고정맥이 2.5 mm 이상으로측정되는경우 1년개존율이 82% 라고하였다.(4) 2. 자가동정맥루의성숙자가동정맥루의성숙에대한판단기준은동정맥루가개존되어있고투석을위한천자에적절할것으로판단되는정도의혈관의확장이관찰되는상태로통상 10 cm 이상의길이에걸쳐 6 mm깊이이내에서 6 mm 이상확장된혈관에혈류량이분당 600 ml 이상으로관찰되는것이다.(21) 투석에사용가능할정도로성숙되지않은동정맥루의경우에는동정맥문합부의협착, 정맥분절의협착, 문합부에가까운곳에부정맥 (accessory vein) 이있는지 Fig. 1. Dynamic Allen s test using duplex ultrasound of the first digit with manual compression of the radial artery. Normal antegrade flow before compression (A) and cessation of the flow after compression (B) indicate inadequate collateral circulation to the hand. 9
J Surg Ultrasound Vol. 3, No. 1, 2016 Volume flow = Average velocity Area, Average velocity = (PSV - EDV)/3 + EDV Fig. 2. Estimation of hemodialysis access volume flow (PSV: peak systolic velocity, EDV: end diasolic velocity). 등을관찰한다.(22) 성숙되지않은동정맥루에서문합부와유입동맥의 2 cm상방에서측정한 PSV ratio 값이 3:1 이상일경우, 그리고유출정맥의 PSV ratio 가 2:1 이상일경우문합부협착이있을가능성이크다.(23) 3. 유지투석환자에서투석접근로의검사 Kidney Disease Outcomes Quality Initiative (KDOQI) 가이드라인에서는투석접근로수술후혈역학적으로의미있는협착의발생여부에대해전향적으로감시하라고권고하고있다.(21,24) 문합부위의협착은수술후시간이지남에따라증가하는데대부분내막과증식으로인해발생한다.(25) 이는정맥이비정상적인동맥의압력을받아일어나는현상으로예방방법은아직알려져있지않다. 그러나초음파감시와더불어막히기전치료를시행할경우개존율이향상되며혈전성폐색의빈도가줄어든다고하였다.(2,26,27) 초음파검사를시행하기전검사자는투석접근로의종류, 수술시기, 재수술이나시술등에관한환자의병력을청취하고이투석접근로를현재투석에이용하고있는지, 투석중혈류량, 동맥압, 정맥압등을알아본다. 초음파로는투석접근로의개존여부, 협착여부, 협착부위및혈종, 감염, 가성동맥류, 도혈증후군, 정맥고혈압등다른합병증들이있는지등에관하여검사한다. 초음파로혈역학적으로의미있는협착의유무를알기위해서는 PSV나 PSV ratio, 혈류량측정, EDV (End diastolic velocity)/psv 비등이이용된다.(28) 정상적인투석접근로의초음파결과는 PSV 100-400 cm/sec, EDV 60-200 cm/sec, 고혈류량 (high flow), 저저항값 (low resistance), spectral broadening 등을보인다. 협착등의이상이의심될때는직경감소비 (Percentage of diameter reduction), PSV, PSV ratio, 혈류량등을측정 하여기록한다. 인조혈관의경우인조혈관과유입동맥유출정맥의문합부전후와인조혈관의중간부위에서각각측정하고그위치를기록한다.(23) 인조혈관투석접근로에서 50% 의협착을시사하는소견은 PSV > 400 cm/sec, PSV ratio 2 or 3 이다.(29-31) 자가혈관을이용한투석접근로에서 50% 이상의협착을시사하는소견은 PSV 400 cm/sec, PSV ratio 2 or 3 ( 문합부혹은협착부위 PSV/ 요골동맥 PSV), 유출정맥에서의 PSV ratio 2 or 3 등이다.(23,28,30,32) 혈류량은혈관의직경, 도플러각도, 컬러박스의 steering, gain, sample volume size 등에의해영향을받는데그중혈관의직경에의해가장크게영향을받으므로주의해야한다 (Fig. 2).(28) 일반적으로혈류량이 800 ml/min 이상일경우정상상태로간주한다.(33) 자가혈관의경우 300 ml/min, 인조혈관의경우 650 ml/min 미만으로측정되면추후폐색이발생할가능성이높다.(34) 결 론 초음파는투석환자에서수술전혈관의상태를파악하고수술방법및위치를결정하는데중요한역할을한다. 수술전초음파로측정하였을때자가동정맥루수술을위해서는정맥이 2 mm 이상혹은압박띠를감았을때 2.5 mm 이상, 인조혈관동정맥루수술을위해서는정맥이 4 mm 이상되어야하고동맥은최소 2 mm 이상되어야수술후성공률이높다. 수술후환자에서초음파로측정한 PSV값이 400 cm/sec 보다크거나 PSV ratio 가 2-3보다크다면협착을의심해야한다. REFERENCES 1. Feldman HI, Kobrin S, Wasserstein A. Hemodialysis vascular access morbidity. J Am Soc Nephrol 1996; 7:523-35. 2. Allon M, Robbin ML. Hemodialysis vascular access monitoring: current concepts. Hemodial Int 2009;13: 153-62. 3. Allon M, Robbin ML. Increasing arteriovenous fistulas in hemodialysis patients: problems and solutions. Kidney Int 2002;62:1109-24. 4. Silva MB Jr, Hobson RW 2nd, Pappas PJ, Jamil Z, Araki CT, Goldberg MC, et al. A strategy for increasing use of autogenous hemodialysis access proce- 10
Byung Wook Park, Hyangkyoung Kim: Ultrasonographic Evaluation of Hemodialysis Access dures: impact of preoperative noninvasive evaluation. J Vasc Surg 1998;27:302-7; discussion 307-8. 5. Habib J, Baetz L, Satiani B. Assessment of collateral circulation to the hand prior to radial artery harvest. Vasc Med 2012;17:352-61. 6. Mihmanli I, Besirli K, Kurugoglu S, Atakir K, Haider S, Ogut G, et al. Cephalic vein and hemodialysis fistula: surgeon's observation versus color Doppler ultrasonographic findings. J Ultrasound Med 2001;20: 217-22. 7. Robbin ML, Gallichio MH, Deierhoi MH, Young CJ, Weber TM, Allon M. US vascular mapping before hemodialysis access placement. Radiology 2000;217: 83-8. 8. Bosman PJ, Boereboom FT, Smits HF, Eikelboom BC, Koomans HA, Blankestijn PJ. Pressure or flow recordings for the surveillance of hemodialysis grafts. Kidney Int 1997;52:1084-8. 9. Zierler BK, Kirkman TR, Kraiss LW, Reiss WG, Horn JR, Bauer LA, et al. Accuracy of duplex scanning for measurement of arterial volume flow. J Vasc Surg 1992;16:520-6. 10. Chandra AP, Dimascio D, Gruenewald S, Nankivell B, Allen RD, Swinnen J. Colour duplex ultrasound accurately identifies focal stenoses in dysfunctional autogenous arteriovenous fistulae. Nephrology (Carlton) 2010;15:300-6. 11. Malovrh M. Native arteriovenous fistula: preoperative evaluation. Am J Kidney Dis 2002;39:1218-25. 12. Wiese P, Nonnast-Daniel B. Colour Doppler ultrasound in dialysis access. Nephrol Dial Transplant 2004;19:1956-63. 13. Malovrh M. The role of sonography in the planning of arteriovenous fistulas for hemodialysis. Semin Dial 2003;16:299-303. 14. Nursal TZ, Oguzkurt L, Tercan F, Torer N, Noyan T, Karakayali H, et al. Is routine preoperative ultrasonographic mapping for arteriovenous fistula creation necessary in patients with favorable physical examination findings? Results of a randomized controlled trial. World J Surg 2006;30:1100-7. 15. Wells AC, Fernando B, Butler A, Huguet E, Bradley JA, Pettigrew GJ. Selective use of ultrasonographic vascular mapping in the assessment of patients before haemodialysis access surgery. Br J Surg 2005;92: 1439-43. 16. Ferring M, Henderson J, Wilmink A, Smith S. Vascular ultrasound for the pre-operative evaluation prior to arteriovenous fistula formation for haemodialysis: review of the evidence. Nephrol Dial Transplant 2008;23:1809-15. 17. Rodriguez E, Ormont ML, Lambert EH, Needleman L, Halpern EJ, Diehl JT, et al. The role of preoperative radial artery ultrasound and digital plethysmography prior to coronary artery bypass grafting. Eur J Cardiothorac Surg 2001;19:135-9. 18. Smith GE, Gohil R, Chetter IC. Factors affecting the patency of arteriovenous fistulas for dialysis access. J Vasc Surg 2012;55:849-55. 19. Mendes RR, Farber MA, Marston WA, Dinwiddie LC, Keagy BA, Burnham SJ. Prediction of wrist arteriovenous fistula maturation with preoperative vein mapping with ultrasonography. J Vasc Surg 2002; 36:460-3. 20. Lockhart ME, Robbin ML, Fineberg NS, Wells CG, Allon M. Cephalic vein measurement before forearm fistula creation: does use of a tourniquet to meet the venous diameter threshold increase the number of usable fistulas? J Ultrasound Med 2006;25:1541-5. 21. KDOQI; National Kidney Foundation. KDOQI Clinical Practice Guidelines and Clinical Practice Recommendations for Anemia in Chronic Kidney Disease. Am J Kidney Dis 2006;47(5 Suppl 3):S11-145. 22. Singh P, Robbin ML, Lockhart ME, Allon M. Clinically immature arteriovenous hemodialysis fistulas: effect of US on salvage. Radiology 2008;246:299-305. 23. American College of Radiology (ACR); Society of Radiologists in Ultrasound (SRU); American Institute of Ultrasound in Medicine (AIUM). AIUM practice guideline for the performance of a vascular ultrasound examination for postoperative assessment of dialysis access. J Ultrasound Med 2014;33:1321-32. 24. Schild AF. Maintaining vascular access: the management of hemodialysis arteriovenous grafts. J Vasc Access 2010;11:92-9. 25. Li L, Terry CM, Shiu YT, Cheung AK. Neointimal hyperplasia associated with synthetic hemodialysis grafts. Kidney Int 2008;74:1247-61. 26. Sands J, Glidden D, Miranda C. Hemodialysis access flow measurement. Comparison of ultrasound dilution and duplex ultrasonography. ASAIO J 1996;42:M899-901. 27. Bay WH, Henry ML, Lazarus JM, Lew NL, Ling J, Lowrie EG. Predicting hemodialysis access failure with color flow Doppler ultrasound. Am J Nephrol 1998;18:296-304. 28. Bandyk DF. Interpretation of duplex ultrasound dialysis access testing. Semin Vasc Surg 2013 26:120-6. 29. Dumars MC, Thompson WE, Bluth EI, Lindberg JS, Yoselevitz M, Merritt CR. Management of suspected hemodialysis graft dysfunction: usefulness of diagnostic US. Radiology 2002;222:103-7. 30. Older RA, Gizienski TA, Wilkowski MJ, Angle JF, Cote DA. Hemodialysis access stenosis: early detection with color Doppler US. Radiology 1998;207:161-4. 31. Robbin ML, Oser RF, Allon M, Clements MW, Dockery J, Weber TM, et al. Hemodialysis access graft stenosis: US detection. Radiology 1998;208:655-61. 32. Grogan J, Castilla M, Lozanski L, Griffin A, Loth F, Bassiouny H. Frequency of critical stenosis in primary arteriovenous fistulae before hemodialysis access: should duplex ultrasound surveillance be the standard 11
J Surg Ultrasound Vol. 3, No. 1, 2016 of care? J Vasc Surg 2005;41:1000-6. 33. Daigle RJ. Techniques in noninvasive vascular diagnosis: an encyclopedia of vascular testing. 3rd ed. Littleton: Summer Pub; 2008. 34. Schäverle W. Ultrasonography in vascular diagnosis. Germany: Springer; 2011. 12