A retrospective study on the risk factors for emergence agitation following general anesthesia

We performed a retrospective study on the risk factors for emergence agitation following general anesthesia in patients undergoing oral surgery in Okayama University Hospital between June 2011 and March 2012. This study was performed after approval by the Ethics Committee of the Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences. One hundred and eighty one patients aged more than 16 years old were enrolled. We used the Richmond Agitation and Sedation Scale (RASS, Table 1), which was developed to assess the level of agitation and sedation following general anesthesia The patients were divided into two groups : non-agitated patients (RASS score : -5 to 0) and agitated patients (RASS score : 1 to 4). The results were statistically analyzed using JMP 9.0.0 (SAS Institute, Cary, USA). In the univariate analysis, Fisher's exact test and the χ² test were used to compare groups. A multivariable analysis was performed using stepwise logistic regression to separately determine risk factors of agitation. Of the 181 patients, emergence agitation occurred in 30 patients (16.6%). Agitation of level 1, 2, 3 or 4 of excitement according to the RASS was observed in 25, 4, 1, and 0 patients, respectively. Table 2 shows the risk factors of emergence agitation using univariate analysis. Emergence agitation was not correlated with age, BMI, duration of operation, postoperative pain, amount of opioid during the operation, or kind of postoperative analgesics, but was more common in males than females (p = 0.039) and also in patients who received general anesthesia than patients who received total intravenous anesthesia (p = 0.011). Table 3 shows the risk factors of emergence agitation using multivariate analysis by stepwise logistic regression. One variable was associated with emergence agitation. Inhalational anesthesia was the highest risk factor (odds ratio [OR] = 3.24; 95% confidence interval [CI] = 1.23-10.17 ; p = 0.015). In conclusion, the results suggest that inhalational anesthesia was the highest risk factor of emergence agitation.