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Background:
The clinical spectrum of hand disability that occurs after autogenous arteriovenous hemodialysis fistula (AVF) creation ranges from subtle alterations in sensation and motor coordination to paraparesis and gangrene. Contemporary dogma has simplistically attributed all aspects of post-AVF hand dysfunction to access-related hand ischemia (ARHI). However, we hypothesize that ARHI alone may not entirely explain the spectrum of dysfunction and, furthermore, that various domains of biomechanical hand function are differentially affected by the mechanisms responsible for creating the observed clinical phenotype. The current study is the first to characterize the post-AVF temporal variation in both hemodynamics and individual biomechanical parameters and determine their correlations.
Methods:
Forty-six patients with end-stage renal disease undergoing surgical creation of an upper extremity AVF from 2013-2015 were prospectively enrolled. Bilateral wrist, first and fifth digit pressures with respective brachial indices were recorded preoperatively and postoperatively at 6-weeks and 6-months. Concurrently, an array of biomechanical tests was administered to evaluate multiple domains of hand function including grip strength(dynamometry), dexterity(Pegboard Test), sensation(first and fifth digit monofilament testing) and hand function perception(Disability of Arm, Shoulder, Hand questionnaire;DASH).
Linear mixed effect models were used to estimate hemodynamic and biomechanical parameter response means and compare them between observation times while accounting for within-patient correlation of responses and accommodating data missingness. Pairwise correlation coefficients and Principal Component analysis (PCA) were utilized to explore associations among hemodynamic and biomechanical parameters and to characterize coherence among these parameters over time. Analysis was performed with SAS and R statistical software.
Results:
Mean age was 60±14 years[75% male(N=36 )] and 22(48%) were already on hemodialysis at the time of access placement. AVF configurations were as follows: 44% brachiocephalic(N=20), 30% distal forearm radiocephalic(N=14) and 26% brachiobasilic(N=12). Six weeks post-operation, a significant decrease in wrist pressure was observed, with only partial recovery at six months(P< .0001;Figure A). PCA demonstrated significant time-dependent clustering indicating similar temporal changes among all hemodynamic measurements (Figure B). Grip strength and DASH score significantly worsened postoperatively with no evidence of improvement during follow-up (P=.021-Figure C;P=.036-Figure D). Digital sensation and limb dexterity changes over time were not statistically significant. Pairwise correlations between all possible combinations of hemodynamic and biomechanical parameters showed no significant correlations (R = -0.10 to 0.31).
Conclusion:
Following AVF creation, all measured hemodynamic parameters exhibited similar temporal patterns, with a significant decrease at 6-weeks followed by partial recovery at 6-months. In contrast, both grip strength and perception of hand function significantly deteriorated without improvement. Interestingly, neither sensation nor dexterity was significantly affected. Overall, no significant correlations existed between hemodynamic and biomechanical changes. The disconnect between perturbations in hemodynamic and biomechanical outcomes suggests that future study is needed to characterize alternative mechanisms of post-AVF hand dysfunction.