A Case of Delayed Emergence After Propofol Anesthesia: Genetic Analysis

Emergence Electroencephalography in an Unresponsiveness Geriatric Patient in the Postanesthesia Care Unit: A Case Report

Incomplete neurological awakening manifested as aberrant patterns of electroencephalography (EEG) at emergence may be responsible for an unresponsive patient in the postanesthesia care unit (PACU). We describe a case of an individual who remained unresponsive but awake in the PACU. Retrospective, intraoperative EEG analysis showed low alpha power and a sudden shift from deep delta to arousal preextubation. We explored parallels with diminished motivation disorders and anesthesia-induced sleep paralysis due to imbalances in anesthetic drug sensitivity between brain regions. Our findings highlight the relevance of end-anesthesia EEG patterns in diagnosing delayed awakening.

Delayed Emergence from Anesthesia: What We Know and How We Act

The emergence from anesthesia is the stage of general anesthesia featuring the patient’s progression from the unconsciousness status to wakefulness and restoration of consciousness. This complex process has precise neurobiology which differs from that of induction. Despite the medications commonly used in anesthesia allow recovery in a few minutes, a delay in waking up from anesthesia, called delayed emergence, may occur. This phenomenon is associated with delays in the operating room, and an overall increase in costs. Together with the emergence delirium, the phenomenon represents a manifestation of inadequate emergence. Nevertheless, in delayed emergence, the transition from unconsciousness to complete wakefulness usually occurs along a normal trajectory, although slowed down. On the other hand, this awakening trajectory could proceed abnormally, possibly culminating in the manifestation of emergence delirium. Clinically, delayed emergence often represents a challenge for clinicians who must make an accurate diagnosis of the underlying cause to quickly establish appropriate therapy. This paper aimed at presenting an update on the phenomenon, analyzing its causes. Diagnostic and therapeutic strategies are addressed. Finally, therapeutic perspectives on the “active awakening” are reported.

Impact of clinical factors and UGT1A9 and CYP2B6 genotype on inter-individual differences in propofol pharmacokinetics

PURPOSE

Propofol is one of the most widely used fast-acting intravenously administered anesthetics. However, although large inter-individual differences in dose requirements and recovery time have been observed, there are few previous studies in which the association between several potential covariates, including genetic factors such as the UGT1A9 and CYP2B6 genotypes, and propofol pharmacokinetics was simultaneously examined. This study aimed to identify factors determining propofol pharmacokinetics.

METHODS

Eighty-three patients were enrolled, and their blood samples were collected 1, 5, 10, and 15 min after administering a single intravenous bolus of propofol at a dose of 2.0 ml/kg to measure propofol plasma concentration. Area under the time-plasma concentration curve from zero up to the last measurable time point (AUC_15min) was determined from the concentration data. The inter-individual variability of the propofol pharmacokinetics was evaluated by investigating relationships between AUC_15min and genotype of UGT1A9 and CYP2B6; clinical factors, such as age, sex, body mass index (BMI), and preoperative hematological examination; and hemodynamic variables measured by a pulse dye densitogram analyzer. The Spearman rank correlation coefficient and the Mann-Whitney U test were used for the statistical analysis of continuous and categorical values, respectively. Subsequently, clinical factors that had p values of < 0.05 in the univariate analysis were examined in a multivariate analysis using multiple linear regression analysis.

RESULTS

Age, BMI, indocyanine green disappearance ratio (K-ICG), hepatic blood flow (HBF), preoperative hemoglobin level, and sex were correlated with AUC_15min (p < 0.05) in univariate analysis. Multivariate analysis performed to adjust for age, BMI, K-ICG, HBF, preoperative hemoglobin level, and sex revealed only BMI as an independent factor associated with AUC_15min.

CONCLUSIONS

This study demonstrated that BMI influences propofol pharmacokinetics after its administration as a single intravenous injection, while UGT1A9 and CYP2B6 SNPs, other clinical factors, and hemodynamic variables do not. These results suggest that BMI is an independent factor associated with propofol pharmacokinetics in several potential covariates.

CLINICAL TRIALS REGISTRATION NUMBER

University Hospital Medical Information Network (UMIN000022948).