Sustained attention test Quatember Maly

With the computerized sustained attention "Clock test" of Quatember and Maly (Wiener Testsystem TM, Schufried, Austria 1994; modified for Task force Vigilance and SIESTA group of DGSM2) the sustained attention will be evaluated under monotone conditions and the processing diligence will be measured in the kind of errors and reaction times over a period of 60 minutes. There are two types of errors: missed and incorrect (delayed) responses reactions. Patients are instructed to press a key on the computer keyboard when the "moving point" in a points circle one point skips. At the beginning of the test will be started shortly to introduce the circular arrangement of points. During implementation, the patients sit in a relaxed position ca. 60-80 cm in front of the screen in a semi-darkened room.

Evaluation

The average reaction rate (in milliseconds), the degree of right, incorrect and omitted responses were recorded at Q&M-sustained attention test.Danker-Hopfe, Sauter and Popp (2006) determined in a standardization study with healthy volunteers cut-off values of more than 3 for omitted responses, more than 4 for incorrect responses and longer than 498 milliseconds for the response times of subjects. Standard values for OS AS patients are not yet available.

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Fig. 7. Sustained attention test by Quatember and Maly (1994) 3.5 Conclusion

The driving simulator Carda, similar to the test developed by Findley, does not fulfil the requirements that are important on a real tracking test. It is rather a reaction test, which describes the attention and the vigilance.

Krieger et al. (1997) were able to demonstrate by means of questionnaires that the accident rate in OSAS patients was often caused by sleepiness and that both the rate of accidents and

2 DGSM = Deutsche Gesellschaft für Schlafforschung und Schlafmedizin (engl.: German Society of Sleep Research and Sleep Medicine)

nearly accidents could be reduced with nCPAP therapy. A test for assessment of accident risk would therefore be helpful.

Findley was found a correlation between the number of accidents and the error rate in a driving simulator test using Steer Clear and data's of Accidents Authority Virginia/USA. He also had verified a certain connection between accident rate and Sleep Apnea Syndrome and a dependence on the severity of the disease (Findley et al. 1989, 1995, 1999, 2000). Tests of this kind should be used only with great caution on the question of driving ability, because it detected only a few aspects.

Due to the simple construction Steer Clear and Carda offer also some advantages, because the technical effort is relatively low and even restricted patients can understand the task very well. However, the tests can only evaluate the response to nCPAP treatment in cases with much higher error rate and can control it course.

Carda

Carsim

Monotony

(+)

+++

Continuity

-

++

Interactivity

-

+++

Usability

+++

++

Table 3. Design and properties of the two simulation programs

Table 3. Design and properties of the two simulation programs

The severity of sleepiness, as assessed by the ESS, didn't correlate with the results of driving simulators. Sleepiness/drowsiness describes the degree of alertnes and will be influenced by central nervous system activation (Weefi et al. 2000). Because the test situation, the sleepiness is often compensated in moderate limitations (ESS < 13) - in our patients, the ESS score was on average = 11.0 - so that the error rate or track deviation showed no relevant dependence. However, in OSAS patients with profound sleepiness (ESS score > 13) a higher number of errors were found in Carda reached a higher (Randerath et al. 2000). Under the testing with Carsim, the number of patients who have had a pathological deviation is much higher. The complex task of interactive driving simulation recorded thus patients with reduced performance, special with difficulties in the divided attention and interactive activities. This could be proven, to persons whose driving performance was checked after alcohol administration with a driving simulator. In OSAS capacity was similar limited to persons with a blood alcohol of 95 + 25 mg/dl (George et al. 1996a). Studies, which correlate the laboratory results of tracking tests with the real frequency of accidents, are still missing. It would be therefore desirable to obtain objective data on road authorities to characterize better any risk patients with this sensitive instrument. A tracking-driving simulator has a higher reality character than a reaction test, because it realized better the task, i.e. the reflection of driving situation (George 2000). Yet here, too, it is important to be sceptical about its evidence power, because the driving performance is dependent of many factors (e.g. responsible acting), which cannot be detected alone by simulation tests. A driving simulator test should be used only as one of several components in the complex assessment of driving ability.

The interactive driving simulator test Carsim, designed by the Ambrock task force, can also be used for further questions: In OSAS patients may be improve due to different treatment modalities several sub-components of attention (such as selective attention, divided attention, sustained attention, processing speed) (Büttner et al. 2000a/b, Büttner 2001). An interactive driving simulator should reflect several of these changes and should be a more suitable instrument, because tracking tasks reflect more components of the limited capabilities in comparison to reaction tests (Carda).

We could demonstrate that an interactive driving simulator (e.g. Carsim) describes the disorder of OSAS patients more sensitive. It is used, therefore, specifically in clinical trials for the assessment of treatment effects to attention increase (e.g., nCPAP or theophylline (Büttner et al. 1999 or 2003a, 2004a)).Due the easy use also Carda will continue to be a suitable method to detect neuropsychological disorders and demonstrate treatment effects in clinical routine.

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