Influence of mild-moderate hypocapnia on intracranial pressure slow waves activity in TBI.
Steiner, Luzius A
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Beqiri, E., Czosnyka, M., Lalou, D., Zeiler, F. A., Fedriga, M., Steiner, L. A., Chieregato, A., & et al. (2020). Influence of mild-moderate hypocapnia on intracranial pressure slow waves activity in TBI.. Acta neurochirurgica, 162 (2), 345-356. https://doi.org/10.1007/s00701-019-04118-6
Background. In Traumatic brain injury (TBI) the patterns of intracranial pressure (ICP) waveforms may 2 reflect pathological processes that ultimately lead to unfavourable outcome. In particular, ICP slow waves 3 (sw) (0.005 – 0.05 Hz) magnitude and complexity have been shown to have positive association with 4 favourable outcome. Mild-moderate hypocapnia is currently used for short periods to treat critical 5 elevations in ICP. Our goals were: to assess changes in the ICP sw activity occurring following sudden onset 6 of mild-moderate hypocapnia; to examine the relationship between changes in ICP sw activity and other 7 physiological variables during the hypocapnic challenge. 8 Methods. ICP, arterial blood pressure (ABP) and bilateral middle cerebral artery blood flow velocity (FV), 9 were prospectively collected in 29 adult severe TBI patients requiring ICP monitoring and mechanical 10 ventilation in whom a minute volume ventilation increase (15-20% increase in respiratory minute volume) 11 was performed as part of a clinical CO2-reactivity test. The time series were first treated using FFT filter 12 (pass-band set to 0.005–0.05 Hz). Power spectral density analysis was performed. We calculated: mean 13 value, standard deviation, variance, coefficient of variation and in the time domain; total power and 14 frequency centroid in the frequency domain; Cerebrospinal compliance (Ci) and compensatory reserve 15 index RAP. 16 Results. Hypocapnia led to a decrease in power and increase in frequency centroid and entropy of slow 17 waves in ICP and FV (not ABP). In a multiple linear regression model RAP at the baseline was the strongest 18 predictor for the decrease in the power of ICP slow waves (p<0.001). 19 Conclusion. In severe TBI patients, a sudden mild-moderate hypocapnia induces a decrease in mean ICP 20 and FV, but also in slow waves power of both signals. At the same time, it increases their higher frequency 21 content and their morphological complexity. The difference in power of the ICP slow waves between the 22 baseline and the hypocapnia period depends on the baseline cerebrospinal compensatory reserve as 23 measured by RAP.
Middle Cerebral Artery, Humans, Hypocapnia, Blood Flow Velocity, Monitoring, Physiologic, Cerebrovascular Circulation, Intracranial Pressure, Adult, Female, Male, Arterial Pressure, Brain Injuries, Traumatic
External DOI: https://doi.org/10.1007/s00701-019-04118-6
This record's URL: https://www.repository.cam.ac.uk/handle/1810/298810
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