Technical Notes & Surgical Techniques
Continuous positive airway pressure alters cranial blood flow and cerebrospinal fluid dynamics at the craniovertebral junction

https://doi.org/10.1016/j.inat.2015.06.004Get rights and content
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Highlights

  • Investigated the impact of CPAP on CSF and cerebral blood flow dynamics.

  • Flow measurements were obtained by PC MRI with PtcCO2, HR and SaO2 monitored.

  • CPAP decreased CSF stroke volume and pulse amplitude.

  • CPAP decreased jugular venous flow pulse amplitude.

  • Findings were attributed to the direct impact of CPAP on intrathoracic pressure.

Abstract

Purpose

To investigate the impact of continuous positive airway pressure (CPAP) applied by a full-face fitted mask at 15 cmH2O on total cerebral blood flow (tCBF), jugular venous flow (tJVF) and cerebrospinal fluid (CSF) flow.

Materials and methods

Axial 2D phase-contrast MRI measurements were acquired at the C2–C3 vertebral level for 23 healthy male awake subjects at baseline (without) and with CPAP applied. CSF flow was quantified within the spinal subarachnoid space and tCBF was quantified based on the summation of blood flow within the left and right internal carotid and vertebral arteries. tJVF was quantified based on the summation of blood flow within the left and right jugular veins. Heart rate, transcutaneous carbon dioxide (PtcCO2) and oxygen saturation were continuously monitored during the MR protocol.

Results

CPAP decreased the pulse amplitude (PtPPA) of tJVF by 21% (p = 0.004). CSF stroke volume (SV) and PtPPA also decreased by 20% (p = 0.003) and 15% (p = 0.005), respectively. Change in tCBF SV and PtPPA was not significant. However, the timing of maximum systolic tCBF occurred significantly earlier under CPAP. CSF flow and tJVF waveforms showed significant spatial and temporal differences in waveform feature points, and spectral analysis revealed a decrease in the first harmonic of tJVF under CPAP (p = 0.001). Under CPAP, a 5% decrease in PtcCO2 (p = 0.003) and 9% increase in HR (p = 0.006) were measured. However, these HR and PtcCO2 changes were not correlated with any changes in arterial, venous or CSF flow dynamics.

Conclusion

Application of CPAP via a full-fitted mask at 15 cm H2O was found to have a significant effect on intracranial venous outflow and spinal CSF flow at the C2 vertebral level in healthy adult-age awake volunteers. CPAP can be used to non-invasively provoke changes in intracranial and CSF flow dynamics.

Keywords

Cerebral blood flow
Cerebrospinal fluid dynamics
Spinal subarachnoid space
Cerebral autoregulation
Cervical spine
Continuous positive airway pressure
Sleep apnea
Intrathoracic pressure
Craniospinal compliance
PtcCO2
2D phase-contrast MRI

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1

Contributed equally to this work.