Background: Inadequate emergence in the postoperative setting is of clinical importance due to
increased morbidity and long-term mortality and is characterized by a disturbance
of activity level in the immediate postoperative period and is classified into two
subtypes—emergence agitation and hypoactive emergence.
Near-infrared spectroscopy (NIRS) has been widely used to measure regional oxygen
saturation (rSO2) in brain tissue during cardiac surgery.
We assessed retrospectively the association between duration and severity of perioperative
rSO2 decrease and the occurrence of inadequate emergence after cardiac surgery
Methods: We enrolled 418 patients over 50 Years of age, without previous psychiatric and neurological
history, who were scheduled for elective cardiac surgery between December 2019 and
December 2021 and among them, 309 patients with sufficient data on rSO2 in this study.
Baseline rSO2 was measured before induction of anesthesia, throughout surgery and
monitored continuously up to 12 hours after operation. Baseline, minimal and average
perioperative rSO2 values as well as areas under the curve (AUCs) at cutoffs of 25%
and 50% of the preoperative baseline values were calculated using the analytic tool.
Inadequate emergence was determined according to the Richmond Agitation-Sedation Scale
(RASS). Emergence agitation was defined as a RASS ≥ +1 point, and hypoactive emergence
was defined as a RASS≤ –2 points.
Results: Of 309 patients (67,03 ± 10,2 years old, 72% male, 28% female), 77 patients (24,9%)
presented with inadequate emergence during the ICU stay. The duration of rSO2 reduction
was significantly longer in patients with inadequate emergence at cutoffs of 25% (p = 0.021) and at cutoffs of 50% (p = 0.043). There was no significant difference regarding sex (p = 0.4), age (p = 0.1) and baseline rSO2 (p = 0.4) but the patients with inadequate emergence had longer duration of ventilation
(p = 0.005).
Conclusion: Perioperative cerebral oxygen saturation decrease was associated with postoperative
inadequate emergence after elective cardiac surgery, although our results need to
be confirmed in a properly sized sample of patients.
