Dynamic cerebral autoregulation is intact in chronic kidney disease

Abstract

Chronic Kidney Disease (CKD) patients experience an elevated risk for cerebrovascular disease. One factor that may contribute to this heightened risk is an impairment in dynamic cerebral autoregulation, the mechanism by which cerebral vessels modulate cerebral blood flow during fluctuations in arterial pressure. We hypothesized that dynamic cerebral autoregulation would be impaired in CKD. To test this hypothesis, we compared dynamic cerebral autoregulation between CKD patients stages III-IV and matched controls (CON) without CKD. Fifteen patients with CKD and 20 CON participants performed 2, 5-minute bouts of repeated sit-to-stand maneuvers at 0.05 Hz and 0.10 Hz while mean arterial pressure (MAP, via finger photoplethysmography) and middle cerebral artery blood velocity (MCAv, via transcranial Doppler ultrasound) were measured continuously. Cerebral autoregulation was characterized by performing a transfer function analysis (TFA) on the MAP-MCAv relationship to derive coherence, phase, gain, and normalized gain (nGain). We observed no group differences in any of the TFA metrics during the repeated sit-to-stand maneuvers. During the 0.05 Hz maneuver, Coherence: CKD = 0.83 ± 0.13, CON = 0.85 ± 0.12, Phase (radians): CKD = 1.39 ± 0.41, CON = 1.25 ± 0.30, Gain (cm/s/mmHg): CKD = 0.69 ± 0.20, CON = 0.71 ± 0.22, nGain (%/mmHg): CKD = 1.26 ± 0.35, CON = 1.20 ± 0.28, p ≥ 0.24. During the 0.10 Hz maneuver (N = 6 CKD and N = 12 CON), Coherence: CKD = 0.61 ± 0.10, CON = 0.67 ± 0.11, Phase (radians): CKD = 1.43 ± 0.26, CON = 1.30 ± 0.23, Gain (cm/s/mmHg): CKD = 0.75 ± 0.15, CON = 0.84 ± 0.26, nGain (%/mmHg): CKD = 1.50 ± 0.28, CON = 1.29 ± 0.24, p ≥ 0.12. Contrary to our hypothesis, dynamic cerebral autoregulation remains intact in CKD stages III-IV. These findings suggest that other mechanisms likely contribute to the increased cerebrovascular disease burden experienced by this population. Future work should determine if other cerebrovascular regulatory mechanisms are impaired and related to cerebrovascular disease risk in CKD.

Keywords: cerebral blood flow; cerebrovascular disease; renal disease; transfer function analysis.

FIGURE 1

Experimental Timeline

FIGURE 2

Representative blood pressure and middle cerebral artery blood velocity (MCAv) tracing during repeated bouts of sit to stand in control participant

FIGURE 3

Transfer function analysis of forced oscillations in mean arterial pressure‐middle cerebral artery blood velocity (MAP‐MCAv) during repeated bouts of sit‐to‐stand at 0.05 Hz. N = 15 CKD (10 M/5F) and N = 20 CON (12 M/8F). MAP‐MCAv coherence, phase, gain, and normalized gain were compared between groups via two‐tailed, unpaired t‐tests. p ≥ 0.24 for all comparisons

FIGURE 4

Transfer function analysis of forced oscillations in mean arterial pressure‐middle cerebral artery blood velocity (MAP‐MCAv) during repeated bouts of sit‐to‐stand at 0.10 Hz. N = 6 CKD (3 M/3F) and N = 12 CON (6 M/6F). MAP‐MCAv coherence, phase, gain, and normalized gain were compared between groups via two‐tailed, unpaired t‐tests. p ≥ 0.12 for all comparisons