In:
PLOS ONE, Public Library of Science (PLoS), Vol. 18, No. 6 ( 2023-6-22), p. e0287578-
Abstract:
Recently, cerebral autoregulation indices based on moving correlation indices between mean arterial pressure (MAP) and cerebral oximetry (NIRS, ORx) or transcranial Doppler (TCD)-derived middle cerebral artery flow velocity (Mx) have been introduced to clinical practice. In a pilot study, we aimed to evaluate the validity of these indices using incremental lower body negative pressure (LBNP) until presyncope representing beginning cerebral hypoperfusion as well as lower body positive pressure (LBPP) with added mild hypoxia to induce cerebral hyperperfusion in healthy subjects. Methods Five male subjects received continuous hemodynamic, TCD and NIRS monitoring. Decreasing levels of LBNP were applied in 5-minute steps until subjects reached presyncope. Increasing levels of LBPP were applied stepwise up to 20 or 25 mmHg. Normobaric hypoxia was added until an oxygen saturation of 84% was reached. This was continued for 10 minutes. ORx and Mx indices were calculated using previously described methods. Results Both Indices showed an increase 〉 0.3 indicating impaired cerebral autoregulation during presyncope. However, there was no significant difference in Mx at presyncope compared to baseline (p = 0.168). Mean arterial pressure and cardiac output decreased only in presyncope, while stroke volume was decreased at the last pressure level. Neither Mx nor ORx showed significant changes during LBPP or hypoxia. Agreement between Mx and ORx was poor during the LBNP and LBPP experiments (R 2 = 0.001, p = 0.3339). Conclusion Mx and ORx represent impaired cerebral autoregulation, but in Mx this may not be distinguished sufficiently from baseline. LBPP and hypoxia are insufficient to reach the upper limit of cerebral autoregulation as indicated by Mx and ORx.
Type of Medium:
Online Resource
ISSN:
1932-6203
DOI:
10.1371/journal.pone.0287578
DOI:
10.1371/journal.pone.0287578.g001
DOI:
10.1371/journal.pone.0287578.g002
DOI:
10.1371/journal.pone.0287578.g003
DOI:
10.1371/journal.pone.0287578.t001
DOI:
10.1371/journal.pone.0287578.s001
DOI:
10.1371/journal.pone.0287578.s002
DOI:
10.1371/journal.pone.0287578.s003
DOI:
10.1371/journal.pone.0287578.r001
DOI:
10.1371/journal.pone.0287578.r002
DOI:
10.1371/journal.pone.0287578.r003
DOI:
10.1371/journal.pone.0287578.r004
Language:
English
Publisher:
Public Library of Science (PLoS)
Publication Date:
2023
detail.hit.zdb_id:
2267670-3
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