Vigilance in patients with obstructive sleep apnea and surgical patients

Aim The Marburg vigilance test (VigiMar) is a vigilance task implemented as a four-choice reaction time task with long duration and low stimulus rate. It tests readiness for reaction under monotonous conditions characterized by sensory deprivation. This study was conducted to compare test results of subjects without sleep disorders to those of patients with untreated obstructive sleep apnea (OSA). In addition, whether patients treated for OSA by continuous positive airway pressure (CPAP) exhibited improvements in vigilance testing and whether subjects without sleep disorders have stable test results in a retest after 2 days were investigated. As test results are given for test thirds separately, these were used to determine whether there was a time-on-task effect for patients with untreated OSA and to check for internal consistency of the VigiMar test. Patients and methods A total of 20 patients with OSA and 20 surgical patients (knee arthroscopy) between 25 and 65 years of age were included. All patients were male. Vigilance testing was performed on the day before CPAP treatment was started or on the day before arthroscopy and 2 days later after the second CPAP night or on the first day after the surgical procedure, respectively. Results In the baseline vigilance test, reaction times of OSA patients were longer than those of surgical patients, especially during the last third of the test. After 2 nights CPAP, reaction times of OSA patients improved to the same level as those of surgical patients who exhibited homogenous results in baseline and postintervention testing. Conclusion The VigiMar test is suitable for the assessment of impaired vigilance. Its internal consistency is high, retest reliability is satisfactory, and it is sensitive for changes in vigilance after only 2 nights CPAP treatment.