Studies of the interaction between mechanoception and nociception would benefit from a method for stimulation of both modalities at the same location. For this purpose, we developed an electrical stimulation device. Using two different electrode geometries, discs and needles, the device is capable of inducing two distinct stimulus qualities, dull and sharp, at the same site on hairy skin. The perceived strength of the stimuli can be varied by applying stimulus pulse trains of different lengths. We assessed the perceived stimulus qualities and intensities of the two electrode geometries at two levels of physical stimulus intensity. In a first series of experiments, ten subjects participated in two experimental sessions. The subjects reported the perceived quality and intensity of four different stimulus classes on visual analogue scales (VASs). In a second series, we added a procedure in which subjects assigned descriptive labels to the stimuli. We assessed the reproducibility of the VAS scores by calculating intraclass correlation coefficients. The results showed that subjects perceived stimuli delivered through the disc electrodes as dull and those delivered through the needles as sharp. Increasing the pulse train length increased the perceived stimulus intensities without decreasing the difference in quality between the electrode types. The intraclass correlation coefficients for the VAS scores ranged from .75 to .95. The labels that were assigned for the two electrode geometries corresponded to the descriptors for nociception and touch reported by other researchers. We concluded that our device is capable of reliably inducing tactile and nociceptive sensations of controllable intensity at the same skin site.Electronic supplementary materialThe online version of this article (doi:10.3758/s13428-012-0216-y) contains supplementary material, which is available to authorized users.

: Changing the amplitude of single rectangular pulse stimuli (SP) has the disadvantage of recruiting tactile and nociceptive fibers in a changing, unknown proportion. Keeping the amplitude constant, but applying a varying number of pulses in a train is another way of stimulus variation, keeping the proportion constant. So, pulse trains (PT) with a variable number of pulses but fixed amplitude might be more suitable to study nonperipheral aspects of processing of stimuli. In this study, we compared the effects of PT and SP stimulation on subjective Numeric Rating Scale scores of perceived stimulus strength and evoked potentials (EP). A total of 41 healthy subjects were electrically stimulated at the left forearm or left middle fingertip using SP and PT stimuli. Numeric Rating Scale scores and EPs were averaged from 105 randomized stimuli at 5 stimulus amplitudes or number of pulses for each subject. The relationships between stimulus amplitudes or number of pulses, EP components and Numeric Rating Scale scores differed depending on the stimulation method and stimulus location. Although the repeatedly reported Numeric Rating Scale-EP (N150-P200) correlation was reproduced for SP at the fingertip, no significant correlation was found for SP stimulation at the forearm. For PT this correlation was found for both stimulus locations. These findings demonstrate that SP and PT involve different ways of processing. The two methods result in different Numeric Rating Scale scores and EP components. Furthermore, PT stimulation is less dependent on stimulus location.

Background Delirium prevention is crucial, especially in critically ill patients. Nonpharmacological multicomponent interventions for preventing delirium are increasingly recommended and technology-based interventions have been developed to support them. Despite the increasing number and diversity in technology-based interventions, there has been no systematic effort to create an overview of these interventions for in-hospital delirium prevention and reduction. Objective This systematic scoping review was carried out to answer the following questions: (1) what are the technologies currently used in nonpharmacological technology-based interventions for preventing and reducing delirium? and (2) what are the strategies underlying these currently used technologies? Methods A systematic search was conducted in Scopus and Embase between 2015 and 2020. A selection was made in line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Studies were eligible if they contained any type of technology-based interventions and assessed delirium-/risk factor–related outcome measures in a hospital setting. Data extraction and quality assessment were performed using a predesigned data form. Results A total of 31 studies were included and analyzed focusing on the types of technology and the strategies used in the interventions. Our review revealed 8 different technology types and 14 strategies that were categorized into the following 7 pathways: (1) restore circadian rhythm, (2) activate the body, (3) activate the mind, (4) induce relaxation, (5) provide a sense of security, (6) provide a sense of control, and (7) provide a sense of being connected. For all technology types, significant positive effects were found on either or both direct and indirect delirium outcomes. Several similarities were found across effective interventions: using a multicomponent approach or including components comforting the psychological needs of patients (eg, familiarity, distraction, soothing elements). Conclusions Technology-based interventions have a high potential when multidimensional needs of patients (eg, physical, cognitive, emotional) are incorporated. The 7 pathways pinpoint starting points for building more effective technology-based interventions. Opportunities were discussed for transforming the intensive care unit into a healing environment as a powerful tool to prevent delirium. Trial Registration PROSPERO International Prospective Register of Systematic Reviews CRD42020175874; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=175874

In order to improve observability of the processing of nociceptive and tactile stimuli, a new electrocutaneous stimulation electrode was developed. The electrode aims at combining the exact timing of electric stimulation with preferential activation of nociceptive or tactile afferents. The electrode is a compound electrode consisting of 5 needle electrodes for preferential stimulation of Aį (nociceptive) fibers and 4 flat electrodes for Aȕ (tactile) fiber stimulation. Stimuli applied with this "bimodal" electrode result in a sharp prickling sensation for the needles and a dull tactile sensation for the flat electrodes. The observed intensity of the stimuli is modulated by varying the number of applied stimulus pulses (NoP). In order to determine the effect of stimuli applied through the bimodal electrode on subjects, a characterization study was performed. The objectives were determining (1) sensation thresholds for both modes of the bimodal electrode, (2) subjective reports following stimulation with the two modes with different intensities and (3) Evoked Potentials (EPs) following these stimuli. 11 subjects (9 male, 2 female) were recruited, each participated in two experiments. After sensation threshold determination, subjects were stimulated with a quasi random sequence of four stimuli (needle or flat electrodes with 1 or 5 pulses), each stimulus was applied 30 times. Subjects rated the perceived sensation on two Visual Analog Scales (VAS), one representing observed quality and one representing observed intensity. EPs were recorded per stimulus type. An electrode was developed which is capable of preferentially stimulating nociceptive and tactile afferents. The needle electrode sensation thresholds were lower than the flat electrode thresholds (0.72±0.42 (mean±SD) mA versus 3.1±1.2 mA). The subject averaged quality VAS score was significantly influenced by mode, the intensity score by NoP. The EPs were significantly influenced by both mode and NoP and suggest a difference in processing between the modes.

Summary Sleep disruption is common among intensive care unit patients, with potentially detrimental consequences. Environmental factors are thought to play a central role in ICU sleep disruption, and so it is unclear why environmental interventions have shown limited improvements in objectively assessed sleep. In critically ill patients, it is difficult to isolate the influence of environmental factors from the varying contributions of non‐environmental factors. We thus investigated the effects of the ICU environment on self‐reported and objective sleep quality in 10 healthy nurses and doctors with no history of sleep pathology or current or past ICU employment participated. Their sleep at home, in an unfamiliar environment (‘Control’), and in an active ICU (‘ICU’) was evaluated using polysomnography and the Richard‐Campbell Sleep Questionnaire. Environmental sound, light and temperature exposure were measured continuously. We found that the control and ICU environment were noisier and warmer, but not darker than the home environment. Sleep on the ICU was perceived as qualitatively worse than in the home and control environment, despite relatively modest effects on polysomnography parameters compared with home sleep: mean total sleep times were reduced by 48 min, mean rapid eye movement sleep latency increased by 45 min, and the arousal index increased by 9. Arousability to an awake state by sound was similar. Our results suggest that the ICU environment plays a significant but partial role in objectively assessed ICU sleep impairment in patients, which may explain the limited improvement of objectively assessed sleep after environmental interventions.