Digital pressure and oxygen saturation measurements in the diagnosis of chronic hemodialysis access-induced distal ischemia

Abstract

Hemodialysis access-induced distal ischemia (HAIDI) can be classified as acute (on the first postoperative day), subacute (≤1 month), or chronic (>1 month), based on the time of onset after access creation. The diagnosis is mainly clinical. However, performing additional tests is beneficial in further assessment of patients. The purpose of this study was to evaluate the use of finger pressure and oxygen saturation measurements for the diagnosis of chronic HAIDI. A total of 20 patients with chronic HAIDI (cases) and 40 asymptomatic hemodialysis patients (controls) were matched for age, sex, etiology of end-stage renal disease, and type of arteriovenous access. Basal digital pressure (BDP), digital pressure during manual compression of access, digital brachial index (DBI), change in digital pressure with access compression (CDP), digital pressure of the contralateral side, and bilateral oxygen saturation (O2 Sat) were measured in all patients. In the case group, compression of the arteriovenous fistula (AVF) increased mean BDP from 61 ± 26 to 118 ± 28 mm Hg (P < .001), which failed to reach the non-AVF side mean digital pressure of 151 ± 25 mm Hg (P < .001). In addition, O2 Sat of the AVF side was significantly lower than the contralateral side (92.9% ± 2.1% vs 95.6% ± 1.4%; P = .001). Among the controls, manual AVF compression raised the mean BDP from 114 ± 36 mm Hg to 133 ± 29 mm Hg (P < .001), which was still significantly lower than the contralateral side mean digital pressure of 141 ± 30 mm Hg (P = .002). In addition, O2 Sat values of the two sides were different (96.7% ± 2.1% vs 97.1% ± 1.9%; P = .01). Comparing the cases and controls, the mean BDP (61 ± 26 mm Hg vs 114 ± 36 mm Hg; P < .001), DBI (0.44 ± 0.16 vs 0.82 ± 0.19; P < .001), and O2 Sat (92.9% ± 2.1% vs 96.7% ± 2.1%; P < .001) were significantly lower and CDP (57 ± 24 mm Hg vs 19 ± 17 mm Hg; P < .001) was significantly higher in the cases than in the controls. The optimal discriminatory thresholds of 80 mm Hg for BDP, 0.7 for DBI, 40 mm Hg for CDP, and 94% for O2 Sat were determined. Digital pressure and O2 Sat measurements are useful additional methods to assist in the clinical evaluation of hemodialysis patients with access-related hand ischemia. BDP <80 mm Hg, DBI <0.7, CDP >40 mm Hg, and O2 Sat <94% are associated with chronic HAIDI.