New indicator of postoperative delayed awakening after total aortic arch replacement

Impact of the decrease of regional cerebral oxygen saturation (rSO2) on postoperative delayed awakening after total aortic arch replacement (TAR) was validated.

From 2008 to 2013, 143 consecutive patients underwent TAR using selective antegrade cerebral perfusion. rSO2 was monitored using near-infrared spectroscopy. We calculated a percent decrease of rSO2 (%-D) immediately after rewarming according to the following formula: %-D=rSO2 (X1)-rSO2 (X2)/rSO2 (X1)×100 (%), where rSO2 (X1) was measured at the beginning of rewarming, and rSO2 (X2) was measured 10 min later. Delayed awakening was defined as patients not waking up for more than 6 h after the termination of anaesthesia.

The average time to wake up was 3.6±2.0 h. Fourteen patients showed delayed awakening. %-D showed a positive linear relationship to awakening time (y=0.67x-0.7, r=0.23, P=0.007) and receiver operating characteristic analysis showed %-D had a good predictive value for delayed awakening (area under the curve=0.84). %-D was significantly different between the delayed awakening and the normal group (7.1±5.1 vs 1.3±6.6%, P=0.002). Two patients (1.4%) who had multicomorbidity with higher %-D died in the hospital due to colon necrosis and sepsis. There were significant differences between patients with normal and delayed awakening in hospital mortality (P=0.04) and transient neurological deficit (TND, P=0.007).

The maintenance of rSO2 at the early phase of rewarming may be important to avoid delayed awakening or TND after TAR.