Impact of sink design on bacterial transmission from hospital sink drains to the surrounding sink environment tested using a fluorescent marker.

In hospitals, sinks act as reservoirs for bacterial pathogens. To assess the extent of splashing, fluorescein dye was added to four hospital sinks previously involved in pathogen dispersal to the environment and/or transmission to patients, and one sink that was not. Applying dye to the p-trap or tailpiece did not result in any fluorescent droplets outside of the drain. When applied to the drain, droplets were found in all but one wash basin, and this was more common in the absence of a drain plug. Sink design considerations to install drain plugs, reduce dripping and offset the tap may help to prevent transmission from drains.

The 'AbdoMAN': an artificial abdominal wall simulator for biomechanical studies on laparotomy closure techniques.

PURPOSE: Incisional hernia remains a frequent complication after abdominal surgery associated with significant morbidity and high costs. Animal and clinical studies have exhibited some limitations. The purpose of this study was to develop an artificial human abdominal wall (AW) simulator in order to enable investigations on closure modalities. We hypothesized that a physical model of the human AW would give new insight into commonly used suture techniques representing a substantial complement or alternative to clinical and animal studies. METHODS: The 'AbdoMAN' was developed to simulate human AW biomechanics. The 'AbdoMAN' capacities include measurement and regulation of intra-abdominal pressure (IAP), generation of IAP peaks as a result of muscle contraction and measurements of AW strain patterns analyzed with 3D image stereo correlation software. Intact synthetic samples were used to test repeatability. A laparotomy closure was then performed on five samples to analyze strain patterns. RESULTS: The 'AbdoMAN' was capable of simulating physiological conditions. AbdoMAN lateral muscles contract at 660 N, leading the IAP to increase up to 74.9 mmHg (range 65.3-88.3). Two strain criteria were used to assess test repeatability. A test with laparotomy closure demonstrated closure testing repeatability. CONCLUSIONS: The 'AbdoMAN' reveals as a promising enabling tool for investigating AW surgery-related biomechanics and could become an alternative to animal and clinical studies. 3D image correlation analysis should bring new insights on laparotomy closure research. The next step will consist in evaluating different closure modalities on synthetic, porcine and human AW.

The 'urge to move' on body supports.

It is well known that people that sit or lie down for prolonged periods change their posture on a regular basis. Even when people are asleep on average 20-40 postural can be observed during an 8 hours period of night rest. One of the reasons that can be found in literature for this 'urge to move' is that these movements are necessary to persevere the blood flow in the tissue. The aim of this paper is to study the relation between tissue perfusion and pressure on the tissue and frequency of the load cycle. Each subject is subjected to a treatment scheme that varies in pressure and frequency of the load on the tissue. The pressure levels that are used are 2.7 kPa, 4.0 kPa and 5.3 kPa and the frequency levels that are used are loading/unloading at intervals of 5 min., 10 min., 15 min. Statistics shows that for 2.7 kPa there is a significant reduction of blood flow between time intervals of 5 min. and 10 min. (P=0.028), and 5 min. and 15 min. (p=0.009). Statistics also shows that there is no significant reduction in blood flow at the time interval of 10 minutes, for every level of pressure. This series of measurements seems to suggest that at the time interval of 10 minutes for every level of pressure the blood flow does not decrease compared to the start situation.

An office chair to influence the sitting behavior of office workers.

Since the introduction of ergonomic guidelines in the design of office chairs, a lot of effort has been put in designing these office chairs accordingly. Because these features all have to be adjusted in different ways (mostly a knob underneath the seat surface), and because every office chair offers different solutions, often users do not use all of the adjustments, and thus do not use the office chair an the optimal ergonomic way. The aim of this paper is to study the influence of feedback on sitting habits of office workers in a field test during 4 weeks. 40 office workers were selected for this test (13 male, 27 female). They were divided in three groups. A control group, a group that received a sitting instruction and a group that received sitting instruction and feedback on their posture every hour that they sit. The results show that there is an effect in average increase in basic posture on both the group that received instruction and the group that received feedback. This effect decreases over time. There was no effect in the control group.

Ergonomic factors on task performance in laparoscopic surgery training.

This paper evaluates the effect of ergonomic factors on task performance and trainee posture during laparoscopic surgery training. Twenty subjects without laparoscopic experience were allotted into 2 groups. Group 1 was trained under the optimal ergonomic simulation setting according to current ergonomic guidelines (Condition A). Group 2 was trained under non-optimal ergonomic simulation setting that can often be observed during training in a skills lab (Condition B). Posture analysis showed that the subjects held a much more neutral posture under Condition A than under Condition B (p<0.001). The subjects had less joint excursion and experienced less discomfort in their neck, shoulders, and arms under Condition A. Significant difference in task performance between Conditions A and B (p<0.05) was found. This study shows that the optimal ergonomic simulation setting leads to better task performance. In addition, no significant differences of task performance, for Groups 1 and 2 using the same test setting were found. However, better performance was observed for Group 1. It can be concluded that the optimal and non-optimal training setting have different learning effects on trainees' skill learning.

Grasping soft tissue by means of vacuum technique.

INTRODUCTION: A notable characteristic of bariatric surgery is the frequent manipulation of the bowel. The bowel is large, delicate, flexible, and has a natural lubricant on the tissue surface. Therefore the bowel is difficult to grasp and manipulate. Vacuum technique is commonly used in industry for all types of grasping and manipulation. Two types of nozzles that differed slightly in geometry (NT1 and NT2), were reviewed in an experimental set up for pull tests on pig bowels. MATERIALS AND METHODS: An experimental set-up was used to conduct a series of pull tests on pig bowel tissue. The basic principle of the measurements was a Newton's force balance; F(Pmax)=Δp×A. Student t-tests, two-way ANOVA and Wilcoxon signed rank tests were conducted for the statistical analysis of NT1 and NT2 with regard to the maximum pull force (F(Pmax)). RESULTS: Concerning NT1 the Newton's force balance could not be confirmed. Concerning NT2 the Newton's force balance could partly be confirmed. For both nozzle types the effect of Δp on F(Pmax) was significant. F(Pmax) increases linear in proportion as Δp increases. This relation between F(Pmax) and Δp was confirmed by the Newton's force balance. DISCUSSION: The results confirm that vacuum technique can be used as a grasp technique for soft organs, particularly the bowels. By means of a clever design of the nozzle a firm grip can be obtained on the bowel segments. Therefore vacuum technique should be studied for further development of instruments, graspers and retractors, to be used in the abdominal area.

Operative notes do not reflect reality in laparoscopic cholecystectomy.

BACKGROUND: Operative notes represent an essential element in safe patient care and should therefore be clear and accurate. This comparative study examined whether operative notes accurately represented the laparoscopic cholecystectomy (LC) as performed. METHODS: Nine Dutch teaching and non-teaching hospitals were invited to record 20 successive LCs each and to collect the corresponding operative notes. The main outcome measures were overall differences and correspondence between video recordings and notes based on the Dutch guideline for LC and the occurrence of iatrogenic gallbladder perforation. A comparison was made of the cumulative results of recordings and operative notes, and individual recordings were compared with the corresponding notes. RESULTS: Seven hospitals participated in the study; 125 video recordings and operative notes were fully analysed. Recordings showed more steps of the procedure than did notes. Individual comparisons showed significant differences (P≤0·001) between the recording and the corresponding note for the steps 'Introducing trocars under vision', 'Condition of the gallbladder', 'Critical view of safety' and 'Removing first and second trocar under vision'. Iatrogenic gallbladder perforation with spilled bile occurred in 31 patients (24·8 per cent), and was both recorded and reported in 29 patients. Iatrogenic gallbladder perforation with spilled bile and spilled stones occurred in 15 patients (12·0 per cent), and was recorded and reported in 11 patients. CONCLUSION: Operative notes do not adequately represent the actual LCs performed as they describe fewer important procedural steps. It is suggested that operative notes should include video recordings.

Discrepant perceptions of communication, teamwork and situation awareness among surgical team members.

OBJECTIVE: To assess surgical team members' differences in perception of non-technical skills. DESIGN: Questionnaire design. SETTING: Operating theatres (OTs) at one university hospital, three teaching hospitals and one general hospital in the Netherlands. PARTICIPANTS: Sixty-six surgeons, 97 OT nurses, 18 anaesthetists and 40 nurse anaesthetists. METHODS: All surgical team members, of five hospitals, were asked to complete a questionnaire and state their opinion on the current state of communication, teamwork and situation awareness at the OT. RESULTS: Ratings for 'communication' were significantly different, particularly between surgeons and all other team members (P ≤ 0.001). The ratings for 'teamwork' differed significantly between all team members (P ≤ 0.005). Within 'situation awareness' significant differences were mainly observed for 'gathering information' between surgeons and other team members (P < 0.001). Finally, 72-90% of anaesthetists, OT nurses and nurse anaesthetists rated routine team briefings and debriefings as inadequate. CONCLUSIONS: This study shows discrepancies on many aspects in perception between surgeons and other surgical team members concerning communication, teamwork and situation awareness. Future research needs to ascertain whether these discrepancies are linked to greater risk of adverse events or to process as well as systems failures. Establishing this link would support implementation and use of complex team interventions that intervene at multiple levels of the healthcare system.

Vacuum grasping as a manipulation technique for minimally invasive surgery.

BACKGROUND: Laparoscopic surgery requires specially designed instruments. Bowel tissue damage is considered one of the most serious forms of lesion, specifically perforation of the bowel. METHODS: An experimental setting was used to manipulate healthy pig bowel tissue via two vacuum instruments. During the experiments, two simple manipulations were performed for both prototypes by two experienced surgeons. Each manipulation was repeated 20 times for each prototype at a vacuum level of 60 kPa and 20 times for each prototype at a vacuum level of 20 kPa. All the manipulations were macroscopically assessed by two experienced surgeons in terms of damage to the bowel. RESULTS: In 160 observations, 63 ecchymoses were observed. All 63 ecchymoses were classified as not relevant and negligible. No serosa or seromuscular damages and no perforations were observed. CONCLUSION: Vacuum instruments such as the tested prototypes have the potential to be used as grasper instruments in minimally invasive surgery.

Tactile feedback exceeds visual feedback to display tissue slippage in a laparoscopic grasper.

Virtual reality can help to learn basic laparoscopic tasks. However, no haptic feedback, which alerts for tissue slippage, is provided by most simulators, although, it might be of influence for the decrease of errors. This study explored whether visual or tactile feedback can be used to alert the surgeon of tissue slippage. Twenty-four participants performed a laparoscopic grasping task and where provided with either visual or tactile feedback about tissue slippage. The reaction time with the visual feedback was compared to the reaction time with tactile feedback signal. The results showed that when tissue slippage is simulated, tactile feedback shows significant faster reaction times (269ms) than visual feedback signals (398ms).

Non-invasive measurement of intra-abdominal pressure: a preliminary study.

The importance of measuring intra-abdominal pressure (IAP) has increased since the negative effects of sustained increased IAP, also known as intra-abdominal hypertension (IAH), have become known. The relation between IAP and abdominal wall tension has been included in several reports. We have developed a device to measure abdominal wall tension by measuring force and distance. This device enables us to investigate the correlation between the abdominal wall tension and IAP. The abdomens of two corpses (one female, one male) were insufflated with air. IAP was increased and measured at intervals by means of a laparoscopic set-up. Abdominal tension was measured at seven points on the abdominal wall at each interval. Pearson's correlation coefficients were used to determine the relationship between IAP and tension for each point measured. ANOVA was used to assess relations between measured tensions versus applied pressure, locations and subjects. In both corpses, all points showed significant (p < 0.001) correlations between IAP and abdominal wall tension. The points along the mid transverse plane appear to be more similar compared to more cranial and caudal points. We have assessed the feasibility of a device that non-invasively can track changes in IAP. Measurements performed with the device are preliminary results, and further investigation is needed.

Biomechanical model study of pelvic belt influence on muscle and ligament forces.

Many patients with low back and/or pelvic girdle pain feel relief after application of a pelvic belt. External compression might unload painful ligaments and joints, but the exact mechanical effect on pelvic structures, especially in (active) upright position, is still unknown. In the present study, a static three-dimensional (3-D) pelvic model was used to simulate compression at the level of anterior superior iliac spine and the greater trochanter. The model optimised forces in 100 muscles, 8 ligaments and 8 joints in upright trunk, pelvis and upper legs using a criterion of minimising maximum muscle stress. Initially, abdominal muscles, sacrotuberal ligaments and vertical sacroiliac joints (SIJ) shear forces mainly balanced a trunk weight of 500N in upright position. Application of 50N medial compression force at the anterior superior iliac spine (equivalent to 25N belt tension force) deactivated some dorsal hip muscles and reduced the maximum muscle stress by 37%. Increasing the compression up to 100N reduced the vertical SIJ shear force by 10% and increased SIJ compression force with 52%. Shifting the medial compression force of 100N in steps of 10N to the greater trochanter did not change the muscle activation pattern but further increased SIJ compression force by 40% compared to coxal compression. Moreover, the passive ligament forces were distributed over the sacrotuberal, the sacrospinal and the posterior ligaments. The findings support the cause-related designing of new pelvic belts to unload painful pelvic ligaments or muscles in upright posture.

Haptics in minimally invasive surgery--a review.

This article gives an overview of research performed in the field of haptic information feedback during minimally invasive surgery (MIS). Literature has been consulted from 1985 to present. The studies show that currently, haptic information feedback is rare, but promising, in MIS. Surgeons benefit from additional feedback about force information. When it comes to grasping forces and perceiving slip, little is known about the advantages additional haptic information can give to prevent tissue trauma during manipulation. Improvement of haptic perception through augmented haptic information feedback in MIS might be promising.

Acquiring basic endoscopy skills by training on the GI Mentor II.

BACKGROUND: Achieving proficiency in flexible endoscopy requires a great amount of practice. Virtual reality (VR) simulators could provide an effective alternative for clinical training. This study aimed to gain insight into the proficiency curve for basic endoscope navigation skills with training on the GI Mentor II. METHODS: For this study, 30 novice endoscopists performed four preset training sessions. In each session, they performed one EndoBubble task and managed multiple VR colonoscopy cases (two in first session and three in subsequent sessions). Virtual reality colonoscopy I-3 was repeatedly performed as the last VR colonoscopy in each session. The assignment for the VR colonoscopies was to visualize the cecum as quickly as possible without causing patient discomfort. Five expert endoscopists also performed the training sessions. Additionally, the performance of the novices was compared with the performance of 20 experienced and 40 expert endoscopists. RESULTS: The novices progressed significantly, particularly in the time required to accomplish the tasks (p < 0.05, Friedman's analysis of variance [ANOVA], p < 0.05, Wilcoxon signed ranks). The experts did not improve significantly, except in the percentage of time the patient was in excessive pain. For all the runs, the performance of the novices differed significantly from that of both the experienced and the expert endoscopists (p < 0.05, Mann-Whitney U). The performance of the novices in the latter runs differed less from those of both the experienced and the expert endoscopists. CONCLUSIONS: The study findings demonstrate that training in both VR colonoscopy and EndoBubble tasks on the GI Mentor II improves the basic endoscope navigation skills of novice endoscopists significantly.

A short history of progression of research into seating and postural support.

Numerous solutions for cushioning the contact area between product and user have been designed during the past centuries, but only in recent decades has systematic research been conducted on the underlying mechanical principles and the consequences of mechanical load imposed on the human skin and muscular skeletal system. In this paper a short history and future perspectives on the research in pressure ulcers is discussed and innovations in the field in the perspective of the history of the innovations are presented. Research in the past century on pressure ulcers has not (yet) led to the eradication of the problem. What can be observed is that the oxygen supply and blood flow to the cells has been studied in many different ways and reported throughout the last century. After the internal capillary pressure was measured in the famous study of Landis, external interface pressures on the tissue was the object of many studies. In these studies different devices that could measure interface pressure were used, but they mainly introduced more sophisticated and innovative means to measured blood flow and oxygenation. After decades of pressure measurements, devices were designed that could measure the missing component of the mechanical load, namely shear. Recently, commercially available shear sensors have been designed, and will, with no doubt, lead to many studies on the combined mechanical load on the tissue. However, although they are interrelated, still a large gap exists between measurements on external mechanical load and the study on the etiology of pressure ulcers.

Stability of sitting postures: the influence of degrees of freedom.

Observational studies of sitting have shown that, during spontaneous sitting, people adopt a variety of postures. Various researchers have formulated theories to explain why people adopt their sitting postures. Branton (1969) hypothesized that there is continual need for postural stability while sitting. Dempster (1955) stated that additional stability could be obtained through temporarily closing chains of body segments, or, in other words, through decreasing the number of degrees of freedom of the body. The present study elaborates on Dempster's theory. The aim of this study was to determine the influence of the degrees of freedom of the body on postural stability in sitting postures. For 21 different sitting postures, the total number of degrees of freedom was determined. Postural sway, a measure for postural stability, was determined using a 3D motion and position measurement system with ten healthy subjects. This study shows that the mean path length at the level of the second thoracic vertebra (PL0.05), a measure derived from postural sway, increases significantly (p < 0.0001) with an increase of the number of degrees of freedom of the body (DoFB). Closer examination of the data showed that a model taking into account only the degrees of freedom of the lumbar and thoracic spine and pelvis seems to be a better predictor of postural sway than the total number of degrees of freedom of the body.

Artificial midline-fascia of the human abdominal wall for testing suture strength.

To reduce testing of human abdominal wall closure-modalities in test animals, a fibre reinforced rubber with identical mechanical properties compared to the human midline fascia (linea alba: LA) was developed. The microscopic structure of the human LA, stress-strain behaviour, maximum tensile force and macroscopic failure mechanism in tensile tests with human LA were defined as indicators for the required properties of the fibre reinforced rubber. A composite consisting of latex rubber and cotton fibres was developed that shows mechanical properties comparable to the human abdominal wall. The results of the tensile tests on sutured artificial LA were highly similar to those performed on sutured human LA. The material presented in this study is proposed as a substitute for human and animal tissues presently used to test suture techniques. A protocol for an approach to develop artificial fibrous soft tissue like fascie and tendon was drawn up.

Application of ergonomic guidelines during minimally invasive surgery: a questionnaire survey of 284 surgeons.

BACKGROUND: This study aimed to obtain an answer for the question: Are ergonomic guidelines applied in the operating room and what are the consequences? METHODS: A total of 1,292 questionnaires were sent by email or handed out to surgeons and residents. The subjects worked mainly in Europe, performing laparoscopic and/or thoracoscopic procedures within the digestive, thoracic, urologic, gynecologic, and pediatric disciplines. RESULTS: In response, 22% of the questionnaires were returned. Overall, the respondents reported discomfort in the neck, shoulders, and back (almost 80%). There was not one specific cause for the physical discomfort. In addition, 89% of the 284 respondents were unaware of ergonomic guidelines, although 100% stated that they find ergonomics important. CONCLUSIONS: The lack of ergonomic guidelines awareness is a major problem that poses a tough position for ergonomics in the operating room.

Sensitivity for pressure difference on the ischial tuberosity.

Although research on sitting and sitting postures has been done for decades, the field of the subjective feeling of comfort or discomfort during sitting is still an unexplored field. On the basis of those studies some manufacturers claim enhanced subjective comfort because of pressure-relieving qualities of the seat cushions. The question is: does a relatively small pressure reduction enhance comfort? Before that question can be answered, the sensitivity for pressure differences applied to the skin must first be determined. The aim of this study was therefore, to determine the sensitivity of the ischial tuberosity for pressure difference in a healthy population. For this study five males and five females aged between 19 and 30 years with no exercise-induced muscle ache were selected. The (Deltaa) was determined for which stimulus (a + Deltaa) was judged as exceeding stimulus (a) in 50% of the trials. This value was called (Deltaa0.5) and was determined with an adapted simple up - down method with forced choice. Two different values for (a) were used: (a) = 13.3 kPa and (a) = 26.5 kPa and the pressure was applied with two different contact surface with diameters of 10 mm and 20 mm. For (a) = 26.5 kPa and d = 10 mm a Deltaa0.5 = 2.7 kPa was found. For (a) = 26.5 kPa and d = 20 mm a Deltaa0.5 = 3.5 kPa was found. For (a) = 13.3 kPa and d = 20 mm a Deltaa0.5 = 1.9 kPa was found.