Effects of −10° and −30° head-down tilt on cerebral blood velocity, dynamic cerebral autoregulation, and noninvasively estimated intracranial pressure

Kato, Tomokazu; Kurazumi, Takuya; Konishi, Toru; Takko, Chiharu; Ogawa, Yutaka; Iwasaki, Katsurô

doi:10.1152/japplphysiol.00283.2021

Cited by 10 publications

(13 citation statements)

References 45 publications

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“…We found that the facial SBF in the cheek decreased as the angle of HDT became steeper. In contrast, no difference has been recognized in cerebral blood flow velocity among three trials in our previous report (Kato et al., 2022). Alterations in the intra‐ and extracranial circulation are thus suggested to differ during HDT.…”

Section: Discussionmentioning

confidence: 55%

“…in cerebral blood flow velocity among three trials in our previous report (Kato et al, 2022). Alterations in the intra-and extracranial circulation are thus suggested to differ during HDT.…”

Section: Cheek Sbf and Extracranial Circulationmentioning

confidence: 52%

“…The participants in the present study were 12 healthy volunteers (three women and nine men; age, 24 ± 2 years; height, 170 ± 8 cm; weight, 67 ± 16 kg) who underwent measurement of cheek SBF, from among a total of 17 participants in our previous experiment to examine the effects of HDT on the cerebral circulation (Kato et al., 2022). None of the subjects had any known medical problems based on our screening medical history and physical examinations.…”

Section: Methodsmentioning

confidence: 99%

“…Details of the procedures were described in the previous report (Kato et al, 2022). Briefly, participants lay supine on an electrical tilting bed (Minato Medical Science, Osaka, Japan), initially set at 0 • , horizontal.…”

Section: Equipmentmentioning

confidence: 99%

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Alteration in facial skin blood flow during acute exposure to −10 and −30° head‐down tilt in young human volunteers

Kurazumi

Kato

Konishi

et al. 2022

Experimental Physiology

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New Findings What is the central question of this study?Facial skin blood flow (SBF) might increase during head‐down tilt (HDT). However, the effect of HDT on facial SBF remains controversial. In addition, the changes in facial SBF in the cheek (cheek SBF) during a steeper angle of HDT (>−12° HDT) have not been investigated. What is the main finding and its importance?This study showed that cheek SBF decreased during −30° HDT, alongside increased vascular resistance. Furthermore, vascular impedance was suggested to be elevated, accompanied by an increased hydrostatic pressure gradient caused by HDT. Constriction of the facial skin vascular bed and congestion of venous return owing to the steep angle of HDT can decrease facial SBF. Abstract Head‐down tilt (HDT) has been used to simulate microgravity in ground‐based studies and clinical procedures including the Trendelenburg position or in certain surgical operations. Facial skin blood flow (SBF) might be altered by HDT, but the effect of a steeper angle of HDT (>−12° HDT) on facial SBF remains unclear. We examined alterations in facial SBF in the cheek (cheek SBF) using two different angles (−10 and −30°) of HDT and lying horizontal (0°) in a supine position for 10 min, to test the hypothesis that cheek SBF would increase with a steeper angle of HDT. Cheek SBF was measured continuously by laser Doppler flowmetry. Cheek skin vascular resistance and the pulsatility index of cheek SBF were calculated to assess the circulatory effects on the facial skin vascular bed in the cheek. Cheek SBF decreased significantly during −30° HDT. In addition, the resistance in cheek SBF increased significantly during −30° HDT. The pulsatility index of cheek SBF increased during both −10 and −30° HDT. Contrary to our hypothesis, cheek SBF decreased during −30° HDT along with increased skin vascular resistance. Vascular impedance, estimated by the pulsatility index in the cheek SBF, was elevated during both −10 and −30° HDT, and elevated vascular impedance would be related to increased hydrostatic pressure induced by HDT. Skin vascular constriction and venous return congestion would be induced by −30° HDT, leading to deceased cheek SBF. The present study suggested that facial SBF in the cheek decreased during acute exposure to a steep angle of HDT (∼−30° HDT).

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Section: Discussionmentioning

confidence: 55%

Section: Cheek Sbf and Extracranial Circulationmentioning

confidence: 52%

Section: Methodsmentioning

confidence: 99%

Section: Equipmentmentioning

confidence: 99%

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Alteration in facial skin blood flow during acute exposure to −10 and −30° head‐down tilt in young human volunteers

Kurazumi

Kato

Konishi

et al. 2022

Experimental Physiology

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“…Non‐invasive cerebral perfusion pressure (nCPP) was also calculated by subtracting nICP from MAP MCA . Cerebrovascular resistance index (CVRi) was calculated as nCPP divided by the 6‐min average of MCAv (Kato et al, 2022 ).…”

Section: Methodsmentioning

confidence: 99%

Steady‐state cerebral blood flow and dynamic cerebral autoregulation during neck flexion and extension in seated healthy young adults

Kato

Konishi

Kurazumi

et al. 2023

Physiological Reports

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Neck flexion and extension show differences in various physiological factors, such as sympathetic nerve activity and intracranial pressure (ICP). We hypothesized that differences would exist in steady‐state cerebral blood flow and dynamic cerebral autoregulation between neck flexion and extension in seated, healthy young adults. Fifteen healthy adults were studied in the sitting position. Data were collected during neck flexion and extension in random order for 6 min each on the same day. Arterial pressure at the heart level was measured using a cuff sphygmomanometer. Mean arterial pressure at the middle cerebral artery (MCA) level (MAP MCA ) was calculated by subtracting the hydrostatic pressure difference between heart and MCA levels from mean arterial pressure at the heart level. Non‐invasive cerebral perfusion pressure (nCPP) was estimated as the MAP MCA minus the non‐invasive ICP as determined from transcranial Doppler ultrasonography. Waveforms of arterial pressure in the finger and blood velocity in the MCA (MCAv) were obtained. Dynamic cerebral autoregulation was evaluated by transfer function analysis between these waveforms. The results showed that nCPP was significantly higher during neck flexion than during neck extension ( p = 0.004). However, no significant differences were observed in mean MCAv ( p = 0.752). Likewise, no significant differences were observed in any of the three indices of dynamic cerebral autoregulation in any frequency range. Although non‐invasively estimated cerebral perfusion pressure was significantly higher during neck flexion than during neck extension, no differences in steady‐state cerebral blood flow or dynamic cerebral autoregulation were evident between neck flexion and extension in seated healthy adults.

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Investigating the effects of tilting the postural drainage lithotripsy system on cerebral blood flow, intracranial pressure, heart rate, and blood pressure

Dai,

Li,

Yang

et al. 2024

World J Urol

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Purpose To investigate the effect of the postural drainage lithotripsy system developed by our experimental team on the vital signs of patient with urinary stones during the stone removal process. Methods Four groups of 15 subjects (0°, 10°, 40°, and 70°) were subjected to different angles of head-down tilt to measure middle cerebral artery blood flow velocity (MCAv), cerebrovascular conductance coefficient (CVCi), intracranial pressure (nICP), heart rate (HR), and mean arterial blood pressure (MAP). Results As the angle of HDT changed, MCAv values, nICP values, CVCi values, HR values, and MAP values changed significantly (all P ≤ 0.001), and the difference was statistically significant. During 10°HDT, despite a slight increase in nICP, the other measurements remained stable. During 40°HDT, only the MCAv values did not change significantly, whereas the rest of the measures were significantly altered. During 70°HDT, all indicators changed significantly. Conclusions The significant alterations in cerebral blood flow, intracranial pressure, and hemodynamics induced during the treatment of renal residual fragments with postural drainage should be used with caution in individuals with cerebrovascular accidents. China Clinical Trials Registry ChiCTR2300070671; Registration date: 2023-04-18.

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Effects of −10° and −30° head-down tilt on cerebral blood velocity, dynamic cerebral autoregulation, and noninvasively estimated intracranial pressure

Cited by 10 publications

References 45 publications

Alteration in facial skin blood flow during acute exposure to −10 and −30° head‐down tilt in young human volunteers

Alteration in facial skin blood flow during acute exposure to −10 and −30° head‐down tilt in young human volunteers

Steady‐state cerebral blood flow and dynamic cerebral autoregulation during neck flexion and extension in seated healthy young adults

Investigating the effects of tilting the postural drainage lithotripsy system on cerebral blood flow, intracranial pressure, heart rate, and blood pressure

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