Sodium nitroprusside dilates cerebral vessels and enhances internal carotid artery flow in young men

TY - JOUR

T1 - Sodium nitroprusside dilates cerebral vessels and enhances internal carotid artery flow in young men

AU - Olesen, Niels Damkjær

AU - Fischer, Mads

AU - Secher, Niels H.

N1 - CURIS 2018 NEXS 296

PY - 2018/9/1

Y1 - 2018/9/1

N2 - Key points: Sodium nitroprusside lowers blood pressure by vasodilatation but is reported to reduce cerebral blood flow. In healthy young men sodium nitroprusside reduced blood pressure, total peripheral resistance, and arterial CO2 tension and yet cerebral blood flow was maintained, with an increase in internal carotid artery blood flow and cerebrovascular conductance. Sodium nitroprusside induces both systemic and cerebral vasodilatation affecting internal carotid artery more than vertebral artery flow. Abstract: Cerebral autoregulation maintains cerebral blood flow (CBF) despite marked changes in mean arterial pressure (MAP). Sodium nitroprusside (SNP) reduces blood pressure by vasodilatation but is reported to lower CBF, probably by a reduction in its perfusion pressure. We evaluated the influence of SNP on CBF and aimed for a 20% and then 40% reduction in MAP, while keeping MAP ≥ 50 mmHg, to challenge cerebral autoregulation. In 19 healthy men (age 24 ± 4 years; mean ± SD) duplex ultrasound determined right internal carotid (ICA) and vertebral artery (VA) blood flow. The SNP reduced MAP (from 83 ± 8 to 69 ± 8 and 58 ± 4 mmHg; both P < 0.0001), total peripheral resistance, and arterial CO2 tension PaCO2; 41 ± 3 vs. 39 ± 3 and 37 ± 4 mmHg; both P < 0.01). Yet ICA flow increased with the moderate reduction in MAP but returned to the baseline value with the large reduction in MAP (336 ± 66 vs. 365 ± 69; P = 0.013 and 349 ± 82 ml min–1; n.s.), while VA flow (114 ± 34 vs. 112 ± 38 and 110 ± 42 ml min–1; both n.s.) and CBF ((ICA + VA flow) × 2; 899 ± 135 vs. 962 ± 127 and 918 ± 197 ml min–1; both n.s.) were maintained with increased cerebrovascular conductance. In conclusion, CBF is maintained during SNP-induced reduction in MAP despite reduced PaCO2 and the results indicate that SNP dilates cerebral vessels and increases ICA flow.

AB - Key points: Sodium nitroprusside lowers blood pressure by vasodilatation but is reported to reduce cerebral blood flow. In healthy young men sodium nitroprusside reduced blood pressure, total peripheral resistance, and arterial CO2 tension and yet cerebral blood flow was maintained, with an increase in internal carotid artery blood flow and cerebrovascular conductance. Sodium nitroprusside induces both systemic and cerebral vasodilatation affecting internal carotid artery more than vertebral artery flow. Abstract: Cerebral autoregulation maintains cerebral blood flow (CBF) despite marked changes in mean arterial pressure (MAP). Sodium nitroprusside (SNP) reduces blood pressure by vasodilatation but is reported to lower CBF, probably by a reduction in its perfusion pressure. We evaluated the influence of SNP on CBF and aimed for a 20% and then 40% reduction in MAP, while keeping MAP ≥ 50 mmHg, to challenge cerebral autoregulation. In 19 healthy men (age 24 ± 4 years; mean ± SD) duplex ultrasound determined right internal carotid (ICA) and vertebral artery (VA) blood flow. The SNP reduced MAP (from 83 ± 8 to 69 ± 8 and 58 ± 4 mmHg; both P < 0.0001), total peripheral resistance, and arterial CO2 tension PaCO2; 41 ± 3 vs. 39 ± 3 and 37 ± 4 mmHg; both P < 0.01). Yet ICA flow increased with the moderate reduction in MAP but returned to the baseline value with the large reduction in MAP (336 ± 66 vs. 365 ± 69; P = 0.013 and 349 ± 82 ml min–1; n.s.), while VA flow (114 ± 34 vs. 112 ± 38 and 110 ± 42 ml min–1; both n.s.) and CBF ((ICA + VA flow) × 2; 899 ± 135 vs. 962 ± 127 and 918 ± 197 ml min–1; both n.s.) were maintained with increased cerebrovascular conductance. In conclusion, CBF is maintained during SNP-induced reduction in MAP despite reduced PaCO2 and the results indicate that SNP dilates cerebral vessels and increases ICA flow.

KW - Cerebral blood flow

KW - Doppler ultrasound

KW - Hypotension

KW - Sodium nitroprusside

U2 - 10.1113/jp275887

DO - 10.1113/jp275887

M3 - Journal article

C2 - 29917239

AN - SCOPUS:85050548503

SN - 0022-3751

VL - 596

SP - 3967

EP - 3976

JO - Journal of Physiology

JF - Journal of Physiology

IS - 17

ER -