Question: Raw EEG data are not routinely acquired during cardiopulmonary bypass (CPB) surgery, where processed data are preferred. Nonetheless, rEEG has a high specificity in detecting ischemic lesions (Florence et al., 2004). In awake patients, after CPB surgery, a global slowing of EEG frequencies has been reported (Zeitelhofer et al., 1988), but no data on continuous EEG during CPB have demonstrated a similar phenomenon. Methods: 16 patients undergoing mitral valve repair, without any other concomitant heart or valve defect, where selected (8 M, 6 F, mean age 64,3 years). 28 channels EEG was continuously recorded during surgery. Anestesia was maintained stable (no bolus) for 10 minutes before the start of CPB , after sternotomy, 30 minutes after CPB beginning and during CPB weaning off (50% of pump activity). These intervals were selected off line, and 2 minutes periods analyzed with a Fast Fourier Transform to obtain the power spectrum density of the 3 periods. A multivariate analysis with Bonferroni correction was then run (p<0.05). Results: data from 12 were analyzed. A global slowing from T1 (pre-CPB) to T3 (post-CPB) emerged, with a diffuse increase of theta frequency (p=0.039). On frontal leads, delta increased with increase of time (p=0.005). Alpha and beta bands pointed to a reduction from T1 to T3 (alpha: temporal leads: 0.014; frontal: 0.003; beta temporo-parietal leads: 0.008), with tendency to appear on more anterior areas than physiological ones. Conclusion: continuous raw EEG recording during CPB surgery demonstrates a global frequencies slowing, with a higher susceptibility of frontal regions. EEG slowing is an indirect index of cortical dysfunction, possibly pointing in our series to hypoxia or riperfusion damage. Figure 1: power spectrum density (μV2/Hz) for delta: 1-4 Hz, theta: 4-7 Hz, alfa:8-12 Hz, beta: 13-30 Hz bands at T1, T2 and T3. Vertical axis cut at 40 Hz to highlight the slower frequencies shift.
Continuous raw EEG recording during cardiopulmonary-bypass (CPB) surgery as a marker of hypoxia.
DEL FELICE, ALESSANDRA;
2014
Abstract
Question: Raw EEG data are not routinely acquired during cardiopulmonary bypass (CPB) surgery, where processed data are preferred. Nonetheless, rEEG has a high specificity in detecting ischemic lesions (Florence et al., 2004). In awake patients, after CPB surgery, a global slowing of EEG frequencies has been reported (Zeitelhofer et al., 1988), but no data on continuous EEG during CPB have demonstrated a similar phenomenon. Methods: 16 patients undergoing mitral valve repair, without any other concomitant heart or valve defect, where selected (8 M, 6 F, mean age 64,3 years). 28 channels EEG was continuously recorded during surgery. Anestesia was maintained stable (no bolus) for 10 minutes before the start of CPB , after sternotomy, 30 minutes after CPB beginning and during CPB weaning off (50% of pump activity). These intervals were selected off line, and 2 minutes periods analyzed with a Fast Fourier Transform to obtain the power spectrum density of the 3 periods. A multivariate analysis with Bonferroni correction was then run (p<0.05). Results: data from 12 were analyzed. A global slowing from T1 (pre-CPB) to T3 (post-CPB) emerged, with a diffuse increase of theta frequency (p=0.039). On frontal leads, delta increased with increase of time (p=0.005). Alpha and beta bands pointed to a reduction from T1 to T3 (alpha: temporal leads: 0.014; frontal: 0.003; beta temporo-parietal leads: 0.008), with tendency to appear on more anterior areas than physiological ones. Conclusion: continuous raw EEG recording during CPB surgery demonstrates a global frequencies slowing, with a higher susceptibility of frontal regions. EEG slowing is an indirect index of cortical dysfunction, possibly pointing in our series to hypoxia or riperfusion damage. Figure 1: power spectrum density (μV2/Hz) for delta: 1-4 Hz, theta: 4-7 Hz, alfa:8-12 Hz, beta: 13-30 Hz bands at T1, T2 and T3. Vertical axis cut at 40 Hz to highlight the slower frequencies shift.
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