A virtual reality simulation of a novel way to illuminate the surgical field - A feasibility study on the use of automated lighting systems in the operating theatre.

Introduction: Surgical lighting systems have to be re-adjusted manually during surgery by the medical personnel. While some authors suggest that interaction with a surgical lighting system in the operating room might be a distractor, others support the idea that manual interaction with the surgical lighting system is a hygiene problem as pathogens might be present on the handle. In any case, it seems desirable to develop a novel approach to surgical lighting that minimizes the need for manual interaction during a surgical procedure. Methodes: We investigated the effect of manual interaction with a classical surgical lighting system and simulated a proposed novel design of a surgical lighting system in a virtual reality environment with respect to performance accuracy as well as cognitive load (measured by electroencephalographical recordings). Results: We found that manual interaction with the surgical lights has no effect on the quality of performance, yet for the price of a higher mental effort, possibly leading to faster fatigue of the medical personnel in the long run. Discussion: Our proposed novel surgical lighting system negates the need for manual interaction and leads to a performance quality comparable to the classical lighting system, yet with less mental load for the surgical personnel.

Investigating the attentional focus to workplace-related soundscapes in a complex audio-visual-motor task using EEG.

Introduction: In demanding work situations (e.g., during a surgery), the processing of complex soundscapes varies over time and can be a burden for medical personnel. Here we study, using mobile electroencephalography (EEG), how humans process workplace-related soundscapes while performing a complex audio-visual-motor task (3D Tetris). Specifically, we wanted to know how the attentional focus changes the processing of the soundscape as a whole. Method: Participants played a game of 3D Tetris in which they had to use both hands to control falling blocks. At the same time, participants listened to a complex soundscape, similar to what is found in an operating room (i.e., the sound of machinery, people talking in the background, alarm sounds, and instructions). In this within-subject design, participants had to react to instructions (e.g., "place the next block in the upper left corner") and to sounds depending on the experimental condition, either to a specific alarm sound originating from a fixed location or to a beep sound that originated from varying locations. Attention to the alarm reflected a narrow attentional focus, as it was easy to detect and most of the soundscape could be ignored. Attention to the beep reflected a wide attentional focus, as it required the participants to monitor multiple different sound streams. Results and discussion: Results show the robustness of the N1 and P3 event related potential response during this dynamic task with a complex auditory soundscape. Furthermore, we used temporal response functions to study auditory processing to the whole soundscape. This work is a step toward studying workplace-related sound processing in the operating room using mobile EEG.

Case Report: How an Iliac Vein Lesion During Totally Endoscopic Preperitoneal Repair of an Inguinal Hernia Can Be Safely Managed.

Inguinal hernia repair is a common surgical procedure with an acceptably low complication rate. However, complications with potentially life-threating consequences may occur in rare cases. These complications might be very challenging to manage, even more in laparo-endoscopic interventions compared to open repair. One of these challenges can be the treatment of an intraoperative injury to the iliac vein. To the best of our knowledge, a lesion of the iliac vein during TEP (totally endoscopic preperitoneal) for inguinal hernia repair, and a safe technique for its management have not been reported yet. We report the case of a 75-year-old male patient with previous abdominal surgery scheduled for TEP repair of an inguinal hernia. During surgery, the iliac vein was damaged. If we had performed a laparotomy in this situation, the potentially life-threatening condition of the patient could have deteriorated further. Instead, to avoid a potential CO2 associated embolism, the preperitoneal pressure was gradually reduced, and the positive end expiratory pressure (PEEP) was increased in the manner that a balance between excessive bleeding and potential development of a CO2 embolism was achieved. The injured vein was sutured endoscopically, and in addition a hemostatic patch was applied. We then continued with the planned surgical procedure. Thrombosis of the sutured vein was prevented by prophylactic administration of low molecular weight heparin until the 14th postoperative day. We conclude that in case of major vein injury during TEP, which might happen irrespective of prior abdominal surgery, the preperitoneal pressure and PEEP adjustment can be used to handle the complication.

Chronically restricted sleep leads to depression-like changes in neurotransmitter receptor sensitivity and neuroendocrine stress reactivity in rats.

STUDY OBJECTIVES: Frequently disrupted and restricted sleep is a common problem for many people in our Western society. In the long run, insufficient sleep may have repercussions for health and may sensitize individuals to psychiatric diseases. In this context, we applied an animal model of chronic sleep restriction to study effects of sleep loss on neurobiological and neuroendocrine systems that have been implied in the pathophysiology of depression, particularly the serotonergic system and the hypothalamic-pituitary-adrenal (HPA) axis. DESIGN: Adult rats were exposed to a schedule of chronic partial sleep deprivation allowing them only 4 h of sleep per day. Sleep restriction was achieved by placing the animals in slowly rotating drums. To examine the regulation and reactivity of the HPA axis, blood samples were collected to measure adrenocorticotropin (ACTH) and corticosterone (CORT) responses. MEASUREMENTS AND RESULTS: While one day of restricted sleep had no significant effect on HPA axis stress reactivity, sleep restriction for a week caused a blunted pituitary ACTH response in a conditioned fear paradigm. Despite this lower ACTH response, adrenal CORT release was normal. The blunted pituitary response may be related to reduced sensitivity of serotonin-1A receptors and/or receptors for corticotropin-releasing hormone (CRH), since sleep restricted rats showed similar reductions in ACTH release to direct pharmacological stimulation with a serotonin-1A agonist or CRH. CONCLUSIONS: Chronic sleep restriction may lead to changes in neurotransmitter receptor systems and neuroendocrine reactivity in a manner similar to that seen in depression. This experimental study thus supports the hypothesis that disrupted and restricted sleep may contribute to the symptomatology of psychiatric disorders.

Dopamine in the orbitofrontal cortex regulates operant responding under a progressive ratio of reinforcement in rats.

Prefrontocortical dopamine (DA) plays an essential role in the regulation of cognitive functions and behavior. The orbitofrontal cortex (OFC) receives a dopaminergic projection from the ventral tegmental area and is particularly important for goal-directed appetitive behaviors and for the neural representation of reward value. We here examined the effects of DA receptor blockers locally infused into the OFC, on instrumental behavior under a progressive schedule of reinforcement. After continuous reinforcement training (lever pressing for casein pellets) rats received bilateral intra-OFC-infusions of the DA D1-receptor antagonist SCH23390 (3 microg/0.5 microl), the DA D2-receptor antagonist sulpiride (3 microg/0.5 microl), or phosphate buffered saline through chronically indwelling cannulae. Immediately after infusion they were tested under a time-constrained progressive ratio schedule of reinforcement (3, 6, 9, 12, ... lever presses for 1 casein pellet within 180 s). Both SCH23390 and sulpiride led to a significant reduction of the break point (cessation to respond to the increasing criterion of instrumental effort) compared to vehicle infusions. A food preference test revealed no drug effects on the amount of consumed pellets and on the preference of casein pellets over laboratory chow. Leftward shifts of the break point in progressive ratio tasks indicate a disturbance of the mechanisms that translate motivation into appetitive behavior under conditions of increasing instrumental effort. Therefore, our data indicate that orbitofrontal dopamine is necessary for reward-related instrumental behavior.