NDT Advance Access originally published online on January 18, 2006
Nephrology Dialysis Transplantation 2006 21(7):2033-2034; doi:10.1093/ndt/gfk065
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Impact of upper extremity abduction on arteriovenous fistula (AVF) blood flow
Email: momose-a{at}oyokyo.jpSir,
It is important to avoid early arteriovenous fistula (AVF) failures in order to achieve maturation of native AVFs. In one case, we experienced a weakened shunt murmur immediately after AVF surgery when the patient's upper extremity AVF side was placed on the trunk in the supine position while the patient was on the operating table. Re-abducting the patient's upper extremity at 90° restored a desirable shunt murmur. Therefore, AVF blood flow (Qa) is thought to be altered not only by bending or extending the hand or elbow joints, but also by shoulder joint abduction. We sought to investigate whether the difference in a patient's upper extremity abduction affects Qa and brachial artery blood flow (Qb).
We recruited 16 patients (five females, age 61±10 years, the age of the AVFs 52±34 months) undergoing maintenance haemodialysis (HD). All AVFs were primary native radiocephalic AVFs at the wrist.
Qa was measured immediately after starting HD. Patients were placed in the supine position with the upper extremity AVF supinated and the elbow and hand joints extended. A patient's upper extremity AVF was abducted at an angle of 0, 45, or 90°, and Qa was measured three times for each position, using the opotodilutional method with the Crit-Line TQA III device.
When significant changes were recorded in the AVF Qa measurement due to altering the position of the upper extremity, Qb was measured using a colour Doppler ultrasound.
There were no significant changes in blood pressure during the Qa and Qb measurements. Of the 16 patients, AVF Qa changes due to upper extremity abduction were recorded in nine patients (56%). Moreover, of these nine patients, Qb changes were observed in six patients (67%) due to abduction of the upper extremity AVF. Based on analysis of the relationships between maximal Qa and Qb and the upper extremity AVF abduction angle, the primary contributed vessel was thought to be a vein in five patients (56%), an artery in two patients (22%), and both a vein and an artery in two patients (22%) (Table 1). It is unclear whether the values of Qa or Qb measured using the Crit Line TQA III or the Doppler ultrasound are correct as the absolute values but those are correct as the relative values. Although the pathophysiology of early AVF failures is not fully understood, many possible risk factors associated with vessel quality and several haemodynamic parameters at AVF creation have been considered [1,2].
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Using venous angiography, Schumacher et al. [3] examined 78 patients whose AVF Qa values were insufficient, and found that an occlusion or significant stenosis of far proximal venous vessels (axillary and/or subclavian vein) could be detected in 14% of these patients. Therefore, in patients whose cephalic vein in upper arm is thin or stenosed, venous blood in upper arm tends to flow into the basilic or brachial veins, such that it tends to be affected by axillary compression. Furthermore, in patients whose deep median cubital vein, a rami communicantes to deep veins, is stenosed, venous blood flows into either the cephalic or basilic veins, such that it is strongly affected by the valve at the brachial junction. Thoracic outlet syndrome (TOS) is caused by compression of the brachial and subclavian arteries or veins at the thoracic outlet region where is the space between the rib cage and the clavicle by excessive arm abduction and external rotation of the upper extremity, and results in diminished blood flow of radial and brachial arteries [4]. Therefore, in a manner similar to TOS, not only Qb but also Qa changes due to positional changes of the upper extremity are likely caused by the compression of both the brachial and subclavian arteries and veins at the thoracic outlet region.
Because of an increasing number of patients with type 2 diabetes mellitus and elderly patients with decreased vascularity, the incidence of early access failure of native radiocephalic AVFs is increasing. Furthermore, in addition to diseased vessels, patients of old age or with diabetes more frequently have degenerated bones, muscles and connective tissues in the shoulders and armpits, as in the TOS patients; therefore, a positional change of the upper extremity may more easily compress arteries and veins. In this study, the patients exhibiting AVF Qa changes due to upper extremity AVF abduction were significantly older than those without AVF Qa changes [5].
Based on the present study, we propose the following guidelines for proper AVF management: (1) prior to AVF creation, the upper extremity position most effective at maintaining the maximal Qb is to be determined and (2) immediately after the operation, the patient is to maintain the upper extremity position that ensures the maximal AVF Qa as measured by auscultation or colour Doppler ultrasound. Although the number of patients in our study was small, our findings will hopefully provide the basis for future prospective studies in more patients, and the incidence of early AVF failures will decrease.
Conflict of interest statement. No conflict of interest in this report stated by all authors.
1 Department of Urology Oyokyo Kidney Research Institute Hirosaki Hospital2 Department of Anatomy Hirosaki University School of Medicine Hirosaki Japan
References
- Kim YO, Yang CW, Yoon SA et al. Access blood flow as a predictor of early failures of native arteriovenous fistulas in hemodialysis patients. Am J Nephrol 2001; 21: 221–225[Medline]
- Ernandez T, Saudan P, Berney T et al. Risk factors for early failure of native arteriovenous fistulas. Nephron Clin Pract 2005; 101: c39–c44[Medline]
- Schumacher KA, Wallner B, Weidenmaier W et al. Venous occlusions distant to the shunt as malfunction factors during hemodialysis. Rofo 1989; 150: 198–201[Medline]
- Kutz JE, Rowland EB Jr. Vascular compression about the shoulder. Hand Clin 1993; 9: 131–138[Medline]
- Rodriguez JA, Armadans L, Ferrer E et al. The function of permanent vascular access. Nephrol Dial Transplant 2000; 15: 402–408
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