A High Risk of Sleep Apnea Is Associated With Less Postoperative Cognitive Dysfunction After Intravenous Anesthesia

Results of an Observational Pilot Study

Soeren Wagner; Joerg Quente; Sven Staedtler; Katharina Koch; Tanja Richter-Schmidinger; Johannes Kornhuber; Harald Ihmsen; Juergen Schuettler


BMC Anesthesiol. 2018;18(139) 

In This Article


Demographics and Clinical Data

We recruited a total of 51 patients, out of which seven patients did not complete the second test phase. Reasons for study dropouts were pain, discomfort and inconveniences leading to time shifts in the second phase test protocol. From the remaining patients, one patient was identified as outlier. Demographic and related clinical data of finally 43 patients used for analysis are given in Table 1. The twenty-two patients assigned to the OSAS group had a median score of 5 (3–7) points in the STOP BANG test and therefore a high risk for OSAS, compared with the patients in the control group with a median score of 2 (1–2) points. OSAS patients and control patients did not differ in age, but the percentage of males was significantly higher in the OSAS group. However, this distribution reflects the epidemiology of sleep apnea, which is far more frequent in males. Correspondingly, the patients in the OSAS group had a significantly higher weight and height. As expected, we also found a significant difference in BMI, since obesity is an important risk factor for sleep apnea and both parameters are used in the STOP BANG questionnaire.

The main type of surgery was otorhinolaryngologic surgery. There were no significant differences regarding dosage and anesthesia procedure between the OSAS and the control group. There were also no differences in oximetry parameters in both groups, although it's notable that we found a slightly more pronounced desaturation in the OSAS subjects after transfer to the recovery room, when the mean oxygen saturation was 96% in the control group and 93% in the OSAS group, respectively.

Neuropsychological Testing

Cognitive function was assessed using a combination of neuropsychological tests on the day before surgery as a baseline measurement. The same test battery was repeated on the first or second postoperative day. Thirty five patients out of 43 patients were tested on the first postoperative day and only eight (three control and five OSAS patients) on the second postoperative day. The pre- and postoperative test results are summarized in Table 2. Preoperatively, significant differences between the two groups were found only for the DemTect, where the patients in the OSAS group showed a significant worse performance compared to the control group (p = 0.0043). When comparing pre- and postoperative values within the control group, there was a significant decrease in three of the tests (DemTect, RMBT, and SKT). In contrast, the patients in the OSAS group did not show a significant loss in any of the tests but even a significantly improved performance in the RMBT test. The differences between the two groups were more obvious when not the absolute values but the difference of the post- and the preoperative values were compared (Table 3). In five of the eight tests (DemTect, RMBT, Digit span forward and backward, and SKT), we found a significant difference between the two groups with respect to the change from pre- to postoperative cognitive function. This statistical significance was confirmed by the ANOVA which revealed high significance for the factor "group" but no significance for the factor "gender" and the interaction between the two factors.