Continuous Optical Monitoring of Cerebral Hemodynamics During Head-of-Bed Manipulation in Brain-Injured Adults



Head-of-bed manipulation is commonly performed in the neurocritical care unit to optimize cerebral blood flow (CBF), but its effects on CBF are rarely measured. This pilot study employs a novel, non-invasive instrument combining two techniques, diffuse correlation spectroscopy (DCS) for measurement of CBF and near-infrared spectroscopy (NIRS) for measurement of cerebral oxy- and deoxy-hemoglobin concentrations, to monitor patients during head-of-bed lowering.


Ten brain-injured patients and ten control subjects were monitored continuously with DCS and NIRS while the head-of-bed was positioned first at 30° and then at 0°. Relative CBF (rCBF) and concurrent changes in oxy- (ΔHbO2), deoxy- (ΔHb), and total-hemoglobin concentrations (ΔTHC) from left/right frontal cortices were monitored for 5 min at each position. Patient and control response differences were assessed.


rCBF, ΔHbO2, and ΔTHC responses to head lowering differed significantly between brain-injured patients and healthy controls (P < 0.02). For patients, rCBF changes were heterogeneous, with no net change observed in the group average (0.3 ± 28.2 %, P = 0.938). rCBF increased in controls (18.6 ± 9.4 %, P < 0.001). ΔHbO2, ΔHb, and ΔTHC increased with head lowering in both groups, but to a larger degree in brain-injured patients. rCBF correlated moderately with changes in cerebral perfusion pressure (R = 0.40, P < 0.001), but not intracranial pressure.


DCS/NIRS detected differences in CBF and oxygenation responses of brain-injured patients versus controls during head-of-bed manipulation. This pilot study supports the feasibility of continuous bedside measurement of cerebrovascular hemodynamics with DCS/NIRS and provides the rationale for further investigation in larger cohorts.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2


  1. 1.

    Durward QJ, Amacher AL, Del Maestro RF, Sibbald WJ. Cerebral and cardiovascular responses to changes in head elevation in patients with intracranial hypertension. J Neurosurg. 1983;59:938–44.

    CAS  PubMed  Article  Google Scholar 

  2. 2.

    Fan JY. Effect of backrest position on intracranial pressure and cerebral perfusion pressure in individuals with brain injury: a systematic review. J Neurosci Nurs. 2004;36:278–88.

    PubMed  Article  Google Scholar 

  3. 3.

    Winkelman C. Effect of backrest position on intracranial and cerebral perfusion pressures in traumatically brain-injured adults. Am J Crit Care. 2000;9(6):373–80.

    CAS  PubMed  Google Scholar 

  4. 4.

    Ropper AH, O’Rourke D, Kennedy SK. Head position, intracranial pressure, and compliance. Neurology. 1982;32:1288–91.

    CAS  PubMed  Article  Google Scholar 

  5. 5.

    Moraine J-J, Berré J, Mélot C. Is cerebral perfusion pressure a major determinant of cerebral blood flow during head elevation in comatose patients with severe intracranial lesions? J Neurosurg. 2000;92:606–14.

    CAS  PubMed  Article  Google Scholar 

  6. 6.

    Feldman Z, Kanter MJ, Robertson CS, et al. Effect of head elevation on intracranial pressure, cerebral perfusion pressure, and cerebral blood flow in head-injured patients. J Neurosurg. 1992;76:207–11.

    CAS  PubMed  Article  Google Scholar 

  7. 7.

    Cruz J, Jaggi JL, Hoffstad OJ. Cerebral blood flow, vascular resistance, and oxygen metabolism in acute brain trauma: redefining the role of cerebral perfusion pressure? Crit Care Med. 1995;23:1412–7.

    CAS  PubMed  Article  Google Scholar 

  8. 8.

    Vespa P. What is the optimal threshold for cerebral perfusion pressure following traumatic brain injury? Neurosurg Focus. 2003;15:E4.

    PubMed  Article  Google Scholar 

  9. 9.

    Juul N, Morris GF, Marshall SB, Marshall LF, Trial ECIS. Intracranial hypertension and cerebral perfusion pressure: influence on neurological deterioration and outcome in severe head injury. J Neurosurg. 2000;92:1–6.

    CAS  PubMed  Article  Google Scholar 

  10. 10.

    Chesnut RM, Temkin N, Carney N, et al. A trial of intracranial-pressure monitoring in traumatic brain injury. N Engl J Med. 2012;367:2471–81.

    CAS  PubMed Central  PubMed  Article  Google Scholar 

  11. 11.

    Cremer OL, van Dijk GW, van Wensen E, et al. Effect of intracranial pressure monitoring and targeted intensive care on functional outcome after severe head injury. Crit Care Med. 2005;33:2207–13.

    PubMed  Article  Google Scholar 

  12. 12.

    Overgaard J, Mosdal C, Tweed WA. Cerebral circulation after head injury. Part 3: does reduced regional cerebral blood flow determine recovery of brain function after blunt head injury? J Neurosurg. 1981;55:63–74.

    CAS  PubMed  Article  Google Scholar 

  13. 13.

    Evans DH, McDicken WN. Doppler ultrasound : physics, instrumentation, and signal processing. 2nd ed. Chichester: Wiley; 2000.

    Google Scholar 

  14. 14.

    Vajkoczy P, Roth H, Horn P, et al. Continuous monitoring of regional cerebral blood flow: experimental and clinical validation of a novel thermal diffusion microprobe. J Neurosurg. 2000;93:265–74.

    CAS  PubMed  Article  Google Scholar 

  15. 15.

    Kirkpatrick PJ, Smielewski P, Czosnyka M, Pickard JD. Continuous monitoring of cortical perfusion by laser Doppler flowmetry in ventilated patients with head injury. J Neurol Neurosurg Psychiatry. 1994;57:1382–8.

    CAS  PubMed Central  PubMed  Article  Google Scholar 

  16. 16.

    Reinhard M, Wehrle-Wieland E, Grabiak D, et al. Oscillatory cerebral hemodynamics: the macro- vs. microvascular level. J Neurol Sci. 2006;250:103–9.

    PubMed  Article  Google Scholar 

  17. 17.

    White H, Venkatesh B. Applications of transcranial Doppler in the ICU: a review. Intensive Care Med. 2006;32:981–94.

    PubMed  Article  Google Scholar 

  18. 18.

    Menon C, Polin GM, Prabakaran I, et al. An integrated approach to measuring tumor oxygen status using human melanoma xenografts as a model. Cancer Res. 2003;63:7232–40.

    CAS  PubMed  Google Scholar 

  19. 19.

    Durduran T. Non-invasive measurements of tissue hemodynamics with hybrid diffuse optical methods. PhD thesis, University of Pennsylvania; 2004.

  20. 20.

    Yu GQ, Durduran T, Zhou C, et al. Noninvasive monitoring of murine tumor blood flow during and after photodynamic therapy provides early assessment of therapeutic efficacy. Clin Cancer Res. 2005;11:3543–52.

    CAS  PubMed  Article  Google Scholar 

  21. 21.

    Sunar U, Makonnen S, Zhou C, et al. Hemodynamic responses to antivascular therapy and ionizing radiation assessed by diffuse optical spectroscopies. Opt Express. 2007;15:15507–16.

    CAS  PubMed  Article  Google Scholar 

  22. 22.

    Zhou C, Eucker SA, Durduran T, et al. Diffuse optical monitoring of hemodynamic changes in piglet brain with closed head injury. J Biomed Opt. 2009;14:034015.

    PubMed Central  PubMed  Article  Google Scholar 

  23. 23.

    Carp SA, Dai GP, Boas DA, Franceschini MA, Kim YR. Validation of diffuse correlation spectroscopy measurements of rodent cerebral blood flow with simultaneous arterial spin labeling MRI; towards MRI-optical continuous cerebral metabolic monitoring. Biomed Opt Express. 2010;1:553–65.

    PubMed Central  PubMed  Article  Google Scholar 

  24. 24.

    Mesquita RC, Skuli N, Kim MN, et al. Hemodynamic and metabolic diffuse optical monitoring in a mouse model of hindlimb ischemia. Biomed Opt Express. 2010;1:1173–87.

    PubMed Central  PubMed  Article  Google Scholar 

  25. 25.

    Kim MN, Durduran T, Frangos S, et al. Noninvasive measurement of cerebral blood flow and blood oxygenation using near-infrared and diffuse correlation spectroscopies in critically brain-injured adults. Neurocrit Care. 2010;12:173–80.

    PubMed Central  PubMed  Article  Google Scholar 

  26. 26.

    Buckley EM, Cook NM, Durduran T, et al. Cerebral hemodynamics in preterm infants during positional intervention measured with diffuse correlation spectroscopy and transcranial Doppler ultrasound. Opt Express. 2009;17:12571–81.

    CAS  PubMed Central  PubMed  Article  Google Scholar 

  27. 27.

    Roche-Labarbe N, Carp SA, Surova A, et al. Noninvasive optical measures of CBV, StO(2), CBF index, and rCMRO(2) in human premature neonates’ brains in the first six weeks of life. Hum Brain Mapp. 2010;31:341–52.

    PubMed Central  PubMed  Article  Google Scholar 

  28. 28.

    Durduran T, Zhou CA, Buckley EM, et al. Optical measurement of cerebral hemodynamics and oxygen metabolism in neonates with congenital heart defects. J Biomed Opt. 2010;15(3):037004.

    PubMed Central  PubMed  Article  Google Scholar 

  29. 29.

    Yu GQ, Floyd TF, Durduran T, et al. Validation of diffuse correlation spectroscopy for muscle blood flow with concurrent arterial spin labeled perfusion MRI. Opt Express. 2007;15:1064–75.

    PubMed  Article  Google Scholar 

  30. 30.

    Zirak P, Delgado-Mederos R, Marti-Fabregas J, Durduran T. Effects of acetazolamide on the micro- and macro-vascular cerebral hemodynamics: a diffuse optical and transcranial doppler ultrasound study. Biomed Opt Express. 2010;1:1443–59.

    CAS  PubMed Central  PubMed  Article  Google Scholar 

  31. 31.

    Edlow BL, Kim MN, Durduran T, et al. The effects of healthy aging on cerebral hemodynamic responses to posture change. Physiol Meas. 2010;31:477–95.

    PubMed  Article  Google Scholar 

  32. 32.

    Durduran T, Zhou C, Edlow BL, et al. Transcranial optical monitoring of cerebrovascular hemodynamics in acute stroke patients. Opt Express. 2009;17:3884–902.

    CAS  PubMed Central  PubMed  Article  Google Scholar 

  33. 33.

    Mesquita RC, Schenkel SS, Durduran T, et al. Diffuse correlation spectroscopy for flow assessment and management of acute ischemic stroke. In: Biomedical optics. Miami: Optical Society of America; 2012. p. BW4B.

  34. 34.

    Durduran T, Yu G, Burnett M, et al. Diffuse optical measurement of blood flow, blood oxygenation, and metabolism in a human brain during sensorimotorcortex activation. Opt Lett. 2004;29:1766–8.

    PubMed  Article  Google Scholar 

  35. 35.

    Durduran T, Choe R, Baker WB, Yodh AG. Diffuse optics for tissue monitoring and tomography. Rep Prog Phys. 2010;73:076701.

    Article  Google Scholar 

  36. 36.

    Mesquita RC, Yodh AG. Diffuse optics: fundamentals and tissue applications. Proceedings of the international school of physics “enrico fermi” course CLXXIII “nano optics and atomics: transport of light and matter waves. 2011;173:51–74.

  37. 37.

    Mesquita RC, Durduran T, Yu G, et al. Direct measurement of tissue blood flow and metabolism with diffuse optics. Philos Trans R Soc A: Math Phys Eng Sci. 2011;369:4390–406.

    CAS  Article  Google Scholar 

  38. 38.

    Boas DA, Yodh AG. Spatially varying dynamical properties of turbid media probed with diffusing temporal light correlation. J Opt Soc Am Opt Image Sci Vis. 1997;14:192–215.

    Article  Google Scholar 

  39. 39.

    Cheung C, Culver JP, Takahashi K, Greenberg JH, Yodh AG. In vivo cerebrovascular measurement combining diffuse near-infrared absorption and correlation spectroscopies. Phys Med Biol. 2001;46:2053–65.

    CAS  PubMed  Article  Google Scholar 

  40. 40.

    Imholz BP, Wieling W, van Montfrans GA, Wesseling KH. Fifteen years experience with finger arterial pressure monitoring: assessment of the technology. Cardiovasc Res. 1998;38:605–16.

    CAS  PubMed  Article  Google Scholar 

  41. 41.

    Teasdale G, Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974;2:81–4.

    CAS  PubMed  Article  Google Scholar 

  42. 42.

    Hunt WE, Hess RM. Surgical risk as related to time of intervention in the repair of intracranial aneurysms. J Neurosurg. 1968;28:14–20.

    CAS  PubMed  Article  Google Scholar 

  43. 43.

    Overgaard J, Tweed WA. Cerebral circulation after head injury. 1. Cerebral blood flow and its regulation after closed head injury with emphasis on clinical correlations. J Neurosurg. 1974;41:531–41.

    CAS  PubMed  Article  Google Scholar 

  44. 44.

    Enevoldsen EM, Jensen FT. Autoregulation and CO2 responses of cerebral blood flow in patients with acute severe head injury. J Neurosurg. 1978;48:689–703.

    CAS  PubMed  Article  Google Scholar 

  45. 45.

    Czosnyka M, Smielewski P, Piechnik S, Steiner LA, Pickard JD. Cerebral autoregulation following head injury. J Neurosurg. 2001;95:756–63.

    CAS  PubMed  Article  Google Scholar 

  46. 46.

    Jaeger M, Schuhmann MU, Soehle M, Nagel C, Meixensberger J. Continuous monitoring of cerebrovascular autoregulation after subarachnoid hemorrhage by brain tissue oxygen pressure reactivity and its relation to delayed cerebral infarction. Stroke. 2007;38:981–6.

    PubMed  Article  Google Scholar 

  47. 47.

    Lang EW, Diehl RR, Mehdorn HM. Cerebral autoregulation testing after aneurysmal subarachnoid hemorrhage: the phase relationship between arterial blood pressure and cerebral blood flow velocity. Crit Care Med. 2001;29:158–63.

    CAS  PubMed  Article  Google Scholar 

  48. 48.

    Ratsep T, Asser T. Cerebral hemodynamic impairment after aneurysmal subarachnoid hemorrhage as evaluated using transcranial Doppler ultrasonography: relationship to delayed cerebral ischemia and clinical outcome. J Neurosurg. 2001;95:393–401.

    CAS  PubMed  Article  Google Scholar 

  49. 49.

    Shenkin HA, Scheuerman WG. Effect of change of position upon the cerebral circulation of man. J Appl Physiol. 1949;2:317–26.

    CAS  PubMed  Google Scholar 

  50. 50.

    Carey BJ, Panerai RB, Potter JF. Effect of aging on dynamic cerebral autoregulation during head-up tilt. Stroke. 2003;34:1871–5.

    PubMed  Article  Google Scholar 

  51. 51.

    Alperin N, Lee SH, Sivaramakrishnan A, Hushek SG. Quantifying the effect of posture on intracranial physiology in humans by MRI flow studies. J Magn Reson Imaging. 2005;22:591–6.

    PubMed  Article  Google Scholar 

  52. 52.

    Young JS, Blow O, Turrentine F, Claridge JA, Schulman A. Is there an upper limit of intracranial pressure in patients with severe head injury if cerebral perfusion pressure is maintained? Neurosurg Focus. 2003;15:E2.

    PubMed  Article  Google Scholar 

  53. 53.

    Mesquita RC, Schenkel SS, Minkoff DL, et al. Influence of probe pressure on the diffuse correlation spectroscopy blood flow signal: extra-cerebral contributions. Biomed Opt Express. 2013 (submitted).

Download references


We are grateful for the contributions of Mark Burnett who initiated the earliest protocols in the neurointensive care unit that led to this study. We also thank Dalton Hance, Justin Plaum, and neurointensive care unit nurses and radiology staff at the Hospital of the University of Pennsylvania for technical assistance. Finally, we acknowledge the Center for Cognitive Neuroscience at the University of Pennsylvania for assistance with control subject recruitment.


Sources of Support (if applicable): Name(s) of Grantor(s), Grant or contract numbers, name of author who received the funding, and specific material support given: National Institute of Heath: NS-054575 (JAD), NS-060653 (AGY), NS-045839 (JAD), HL077699 (AGY), RR-02305 (AGY, JAD), R25-NS065743 (BLE). TD gratefully acknowledged partial support by Fundacio Cellex Barcelona, Marie Curie IRG (FP7, RPTAMON), Institute de Salud Carlos III (DOMMON, FIS), Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Comepetitividad, Institució CERCA (DOCNEURO, PROVAT-002-11), Generalitat de Catalunya, European Regional Development Fund (FEDER/ERDF) and LASERLAB (FP7) and Photonics4Life (FP7) consortia. University of Pennsylvania Research Foundation (JHG). Financial Disclosure AGY, JAD, JHG, TD are co-inventors on patents related to the optical technology. However, they do not receive any income or royalties from those patents.

Author information



Corresponding author

Correspondence to Meeri N. Kim.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kim, M.N., Edlow, B.L., Durduran, T. et al. Continuous Optical Monitoring of Cerebral Hemodynamics During Head-of-Bed Manipulation in Brain-Injured Adults. Neurocrit Care 20, 443–453 (2014).

Download citation


  • Diffuse correlation spectroscopy
  • Near-infrared spectroscopy
  • Diffuse optical spectroscopy
  • Head-of-bed
  • Cerebral blood flow
  • Neurocritical care
  • Cerebral hemodynamics