The study aimed to evaluate the effects of 24-Hour-Call-associated acute partial sleep deprivation on surgical residents' technical and cognitive performance in a virtual reality (VR) setting. Physiological parameters were used to quantify fatigue in respect to hours of sleep and subjective degrees of sleepiness. Technical performance and cognitive skills were assessed through low- and high fidelity tasks usig the VR- simulator LapSim. Objective alertness was measured by the standardized d2-Paper-Pencil-Test. Cited assessments were performed on three consecutive mornings- pre- and post-call as after 24 hours resting.

Summary Background Data:

The effect of acute partial sleep deprivation on surgical proficiency is still controversially discussed. The present study is the first to measure objective physiological parameters of fatigue in respect to subjective perceptions of sleepiness in VR- research of surgical performance.

Methods:

38 surgeons were explored on three consecutive mornings: prior to a 24-Hour- Call, post-call and after 24 hours resting. Hours of sleep were recorded. Subjective alertness was assessed using the standardized Stanford-Sleepiness-Scale (SSS). Saliva cortisol concentrations and pupillary activity were measured by ELISA and pupillography. The VR-simulator LapSim® was used to assess technical skills through defined low- fidelity VR-tasks "cutting", "clip applying" and cognitive skills through defined high-fidelity VR-tasks "intracorporal suturing", "VR-cholecystectomy". Objective alertness was measured by the standardized d2-Paper-Pencil-Test.

Inclusion Criteria:

• Surgical interns, junior- or senior residents
• Successful completion of a minimum of 10 basic VR- tasks with the VR- simulator LapSim: "camera navigation", "coordination", "clip applying", "Cutting", and "diathermy cutting" and a minimum of 5 sessions of advanced VR- tasks: "fine dissection", "intracorporal suturing" and "VR- cholecystectomy"
• Voluntary participation
• Written informed consent

Exclusion Criteria:

• Lack of required VR- training
• Lack of informed consent

• 38 surgeons (20 male, 18 female)
• 4 senior registrars, 15 junior registrars, 19 interns
• age 24-48 years; mean 30 years