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A1034
October 16, 2006
2:00 PM - 4:00 PM
Room Hall E, Area I
Brain Oxyhemoglobin Stimulation during Intubation
William E. Hoffman, Ph.D., Rodolfo Gatto, M.D., Verna L. Baughman, M.D., Fady Charbel, M.D.
Anesthesiology and Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
Introduction It is reported that regional cerebral blood flow, oxyhemoglobin and blood volume increase and brain deoxyhemoglobin concentration decreases during brain stimulation, measured by function magnetic resonance imaging and near infrared spectroscopy (Toronov et al. 2003; Huppert et al. 2006). Patient stimulation during intubation may produce a generalized increase in neuronal stimulation. The purpose of this study was to compare the change in oxyhemoglobin (OHb) and deoxyhemoglobin (HHb) concentrations during intubation between the right and left frontal cortex, measured by frequency domain NIRS (FD-NIRS).

Methods Twelve neurosurgery patients without cerebral pathology were recruited for this study. Brain OHb, HHb and total hemoglobin were determined bilaterally in each patient using an Oxiplex TS (ISS, Champaign, IL). The probes were placed 2 cm above the eyebrow, 1 cm lateral from the midline on the forehead and was shielded from outside light during the measures. Data were collected every 2 seconds. Entropy EEG sensors were placed on the right hemisphere. Non-invasive blood pressure and heart rate were measured. Treatments: 1 = awake breathing 100% oxygen by mask, 2 = anesthesia with fentanyl and propofol, 3 = intubation, 4 = after 20 minutes of desflurane anesthesia. Data were analyzed by repeated measures analysis of variance.

Results OHb and HHb concentrations did not change during propofol anesthesia (table 1). Intubation was associated with an increase in OHb and total hemoglobin and a decrease in HHb that were greater in the left compared to the right hemisphere. Response Entropy increased from 31 + 11 to 53 + 18 and blood pressure from 87 + 17 mmHg to 114 + 22 mmHg during intubation. Total hemoglobin remained elevated for several minutes after blood pressure returned to baseline. Over all treatments, OHb and total hemoglobin were higher in the left compared to the right hemisphere (P < 0.05).

Conclusion These results suggest that neuronal activation associated with oro-tracheal stimulation increased brain oxygenation more in the left than the right hemisphere. The increase in oxyhemoglobin is likely related to an increase in cerebral blood flow as reported for neuronal stimulation (Huppert et al. 2006). It is possible that the magnitude and length of the increase in OHb and total hemoglobin is related to adequacy of anesthesia and the intensity of brain activation.

References

1. Huppert, T. J., R. D. Hoge, et al. (2006). "A temporal comparison of BOLD, ASL, and NIRS hemodynamic responses to motor stimuli in adult humans." Neuroimage 29(2): 368-82.

Toronov, V., S. Walker, et al. (2003). "The roles of changes in deoxyhemoglobin concentration and regional cerebral blood volume in the fMRI BOLD signal." Neuroimage 19(4): 1521-31.[table1]

Anesthesiology 2006; 105: A1034
Oxyhemoglobin (OHb) and Deoxyhemoglobin (HHb)
AwakeAnesthesiaIntubationDesflurane
Right OHb (uM)15.8 +/- 7.815.5 +/- 7.519.3 +/- 9.6*15.2 +/- 7.7
Left OHb (uM)18.8 +/- 8.418.9 +/- 8.625.1 +/- 10.7*19.8 +/- 10.0
Right HHb (uM)12.4 +/- 3.112.6 +/- 3.511.4 +/- 3.712.8 +/- 4.1
Left HHb (uM)12.7 +/- 2.912.5 +/- 2.910.5 +/- 2.7*12.9 +/- 3.2
Mean +/- SD, * = P <0.05 compared to Awake