Relationship between occupational stress injury score and simulated patient-care scenario performance among experienced paramedics.

BACKGROUND: It is well-known that psychosocial health status of paramedics may be altered by their job demands. However, it is unknown whether psychosocial health status can affect occupational performance. OBJECTIVE: The goal of this study was to explore whether a paramedic's symptom severity of Occupational Stress Injury (OSI) was related to simulated patient-care performance. METHODS: Nineteen paramedics with 15.0±8.7 years of paramedic experience participated in this study. Participants completed both an OSI symptom severity questionnaires, and a patient-care simulation. Vagal activity was also collected during the patient-care simulation. The simulation was used to assess experienced paramedics in a realistic stressful setting. Based on the provincial standard in New Brunswick, an experienced paramedic instructor graded the patient-care simulation using the provincial standard charts, observing performance videos and assessing data from the manikin. RESULTS: The current study suggests that paramedics who self-reported elevated symptoms of OSI were less likely to successfully complete the simulated patient-care scenario. CONCLUSION: This research suggests that the presence of self-reported elevated symptoms of OSI negatively impacts paramedics' performance during a stressful work task simulation. Therefore, to help paramedics maintain optimal performance, it may be important to ensure that paramedics have access to appropriate resources to monitor and improve their psychosocial health.

Occupational health profile of Canadian Maritimes truck drivers.

BACKGROUND: There are over 12,000 professional truck drivers in the Canadian Maritime provinces, with the majority being in New Brunswick and Nova Scotia. Previous studies have focused on the health of Canadian and American truck drivers but the occupational health status of truck drivers in the Maritime Provinces remains undocumented. OBJECTIVE: The objective of this cross-sectional study was to provide a general, occupational health and demographic characteristics description of professional truck drivers in the Maritimes. METHODS: One-hundred and four male truck drivers from the Canadian Maritime Provinces volunteered for this study. Nine occupational health indicators were measured (seven were self-reported via questionnaire and two were physical measurements). Participants self-reported their age, years of truck driving experience and education. RESULTS: Only one-quarter of the current sample had no health conditions. In contrast, more than half were obese, one third had back problems, and one-sixth had a high risk of developing cardiovascular disease (CVD). The group comparison analysis showed that the group without health condition was younger and more educated than the group with multiple health conditions. For this study, age and low rate of education were associated with an increased number of health conditions. CONCLUSIONS: Similar to health profiles of other populations of North American truck drivers, this study suggests that the majority of truck drivers in the Canadian Maritime Provinces have at least one poor indicator of occupational health.

Physiological responses during paramedics' simulated driving tasks.

BACKGROUND: Most ambulance collisions happen in emergency driving conditions and are caused by human factors. OBJECTIVE: This study investigated the influence of human factors associated with time pressure, patient-care intervention, and health status on the physiological responses of simulated emergency driving tasks. METHODS: A cohort of seventeen experienced paramedics performed a battery of three simulated diving tasks. The driving tasks were a non-urgent and two urgent driving simulations (one to the scene and one to the hospital). The second urgent driving task was preceded by a patient-care simulation (unstable cardiac patient with cardiopulmonary resuscitation). RESULTS: The physiological responses between the three driving tasks were not significantly different due to time pressure and patient-care intervention. It is postulated that the physiological response of experienced paramedics was influenced by the fact that they are accustomed to handling stressful situations daily. Furthermore, it was observed that paramedics with health conditions were more physiologically aroused during the urgent driving scenarios (pre and post-intervention), suggesting they might have an elevated risk of collision when they drive with urgency. Paramedics with health conditions also had higher physiological responses for the post-intervention baseline, leading to a longer recovery time period, which might represent an elevated risk of developing chronic health problems or amplifying existing ones. CONCLUSIONS: The findings of this research suggest that experienced paramedics manage the influence of time pressure and the impact of challenging patient-care well. Paramedics with health conditions represent an elevated risk of collision.

Exploration of the health status of experienced New Brunswick paramedics.

BACKGROUND: Literature reports that paramedics represent an at-risk occupation for the development of health problems. At least half of the paramedic population presents at least one risk factor associated with a negative health condition. These reports may suffer a "mono-method bias" where most reported outcomes are based on a single screening tool approach (may attenuate or inflate the prevalence). OBJECTIVE: The current study characterizes the health status of a cohort of twenty-five experienced New Brunswick (Canadian province) paramedics. METHODS: To understand possible limitations of past research, health status was characterized using four different methods: two methods using only one health measure and two were combined methods, integrating outcomes from at least two health measures to determine the prevalence of a given health status. RESULTS: Mono-bias was observed when using the single health measure methods. The difference among the four methods highlighted that a third of the cohort seemed unaware of their health condition. This result shed additional light on paramedics' health, where a high proportion of paramedics worked without knowledge of their health conditions. Based on a two health measures combined method, it was observed that only two-fifths of the current sample had no health conditions or could otherwise be considered as a "healthy". CONCLUSIONS: Because the literature has focused on single screening methods, our results were difficult to compare. However, there was a consensus that paramedics represent an at-risk occupation comprised of health problems. This study was exploratory and should be the basis for further research.

Exploring simulated driving performance among varsity male soccer players.

Background: It is documented that male athletes display riskier behaviors while driving (as well as in life in general) than female athletes and nonathletes. However, the literature has reported that athletes show better driving ability than nonathletes. This paradox between behaviors and abilities motivated the present study to further understand the collision risk of varsity athletes. Objective: The current study estimates the performance differences between varsity male soccer players and male undergraduate nonathletes on (1) a driving task and (2) three perceptual-cognitive tasks (associated with collision risk prediction; i.e., Useful Field of View [UFOV] test). Methods: Thirty-five male undergraduate students (15 varsity soccer players, 20 undergraduate nonathletes) took part in this study. Driving performance was assessed during 14 min of urban commuting using a driving simulator. While completing the simulated driving task and UFOV test, the physiological responses were monitored using an electrocardiograph (ECG) to document heart rate variability (HRV). Results: Varsity soccer players showed more risky behaviors at the wheel compared to their nonathlete student peers. Varsity soccer players spent more time over the speed limit, committed more driving errors, and adopted fewer safe and legal behaviors. However, no difference was observed between both groups on driving skill variables (i.e., vehicle control, vehicle mobility, ecodriving). For subtests 1 and 2 of the UFOV (i.e., processing speed, divided attention), both groups performed identically (i.e., 17 ms). The nonathlete group tended to perform better on the selective attention task (i.e., subtest 3 of UFOV test; 63.2 ± 6.2 ms vs. 87.2 ± 10.7 ms, respectively; this difference was not significant, P = .76). Conclusion: Preventive driving measures should be enforced in this high-risk population to develop strategies for risk reduction in male team athletes.

Ergonomic evaluation of a new truck seat design: a field study.

A postural evaluation of commercial licensed truck drivers was conducted to determine the ergonomic benefits of a truck seat prototype in comparison with an industry standard seat. Twenty commercially licensed truck drivers were recruited to perform a 90-min driving task. Postures were assessed using accelerometers and a backrest and seat pan pressure mapping system. Subjective discomfort measurements were monitored using two questionnaires: ratings of perceived discomfort (RPD) and the automotive seating discomfort questionnaire (ASDQ). Participants reported significantly higher discomfort scores when sitting in the industry standard seat. Participants sat with more lumbar lordosis and assumed a more extended thoracic posture when seated in the prototype. Pairing the gluteal backrest panel with the adjustable seat pan also helped reduce the average sitting pressure on both the seat pan and the backrest. The prototype provided several postural benefits for commercially certified truck drivers, as it did for a young and healthy population.

Quantitative feature analysis of continuous analytic wavelet transforms of electrocardiography and electromyography.

Theoretical and practical advances in time-frequency analysis, in general, and the continuous wavelet transform (CWT), in particular, have increased over the last two decades. Although the Morlet wavelet has been the default choice for wavelet analysis, a new family of analytic wavelets, known as generalized Morse wavelets, which subsume several other analytic wavelet families, have been increasingly employed due to their time and frequency localization benefits and their utility in isolating and extracting quantifiable features in the time-frequency domain. The current paper describes two practical applications of analysing the features obtained from the generalized Morse CWT: (i) electromyography, for isolating important features in muscle bursts during skating, and (ii) electrocardiography, for assessing heart rate variability, which is represented as the ridge of the main transform frequency band. These features are subsequently quantified to facilitate exploration of the underlying physiological processes from which the signals were generated.This article is part of the theme issue 'Redundancy rules: the continuous wavelet transform comes of age'.

Biomechanical investigation of prolonged driving in an ergonomically designed truck seat prototype.

A postural evaluation during a prolonged driving task was conducted to determine the ergonomic validity of a new freely adjustable truck seat prototype. Twenty participants were recruited to perform two 2-h simulated driving sessions. Postures were assessed using motion capture, accelerometers and pressure pads. Subjective discomfort was also monitored in 15-min increments using ratings of perceived discomfort (RPD) and the Automotive Seating Discomfort Questionnaire. Participants had a more neutral spine posture during the first hour of the drive and reported lower RPDs while sitting in the prototype. Pairing the gluteal backrest panel with the adjustable seat pan helped reduce the average sitting pressure. The industry-standard truck seat may lead to the development of poor whole body posture, and the proposed ergonomic redesign of a new truck seat helped improve sitting posture and reduce perceived discomfort. Practitioner Summary: A new freely adjustable truck seat prototype was compared to an Industry standard seat to assess hypothesised improvements to sitting posture and discomfort for long haul driving. It was found that the adjustable panels in the prototype helped promote spine posture, reduce sitting pressure and improved discomfort ratings.

Assessing heart rate variability through wavelet-based statistical measures.

Because of its utility in the investigation and diagnosis of clinical abnormalities, heart rate variability (HRV) has been quantified with both time and frequency analysis tools. Recently, time-frequency methods, especially wavelet transforms, have been applied to HRV. In the current study, a complementary computational approach is proposed wherein continuous wavelet transforms are applied directly to ECG signals to quantify time-varying frequency changes in the lower bands. Such variations are compared for resting and lower body negative pressure (LBNP) conditions using statistical and information-theoretic measures, and compared with standard HRV metrics. The latter confirm the expected lower variability in the LBNP condition due to sympathetic nerve activity (e.g. RMSSD: p=0.023; SDSD: p=0.023; LF/HF: p=0.018). Conversely, using the standard Morlet wavelet and a new transform based on windowed complex sinusoids, wavelet analysis of the ECG within the observed range of heart rate (0.5-1.25Hz) exhibits significantly higher variability, as measured by frequency band roughness (Morlet CWT: p=0.041), entropy (Morlet CWT: p=0.001), and approximate entropy (Morlet CWT: p=0.004). Consequently, this paper proposes that, when used with well-established HRV approaches, time-frequency analysis of ECG can provide additional insights into the complex phenomenon of heart rate variability.

Driving performance on the descending limb of blood alcohol concentration (BAC) in undergraduate students: a pilot study.

Young drivers are overrepresented in collisions resulting in fatalities. It is not uncommon for young drivers to socially binge drink and decide to drive a vehicle a few hours after consumption. To better understand the risks that may be associated with this behaviour, the present study has examined the effects of a social drinking bout followed by a simulated drive in undergraduate students on the descending limb of their BAC (blood alcohol concentration) curve. Two groups of eight undergraduate students (n = 16) took part in this study. Participants in the alcohol group were assessed before drinking, then at moderate and low BAC as well as 24 hours post-acute consumption. This group consumed an average of 5.3 ± 1.4 (mean ± SD) drinks in an hour in a social context and were then submitted to a driving and a predicted crash risk assessment. The control group was assessed at the same time points without alcohol intake or social context.; at 8 a.m., noon, 3 p.m. and 8 a.m. the next morning. These multiple time points were used to measure any potential learning effects from the assessment tools (i.e. driving simulator and useful field of view test (UFOV)). Diminished driving performance at moderate BAC was observed with no increases in predicted crash risk. Moderate correlations between driving variables were observed. No association exists between driving variables and UFOV variables. The control group improved measures of selective attention after the third assessment. No learning effect was observed from multiple sessions with the driving simulator. Our results show that a moderate BAC, although legal, increases the risky behaviour. Effects of alcohol expectancy could have been displayed by the experimental group. UFOV measures and predicted crash risk categories were not sensitive enough to predict crash risk for young drivers, even when intoxicated.

Body position differentially influences responses to exogenous and endogenous cues.

The influence of vestibular inputs on exogenous (Exp. 1) and endogenous (Exp. 2) orienting of visual attention was examined. The vestibular system was manipulated through a change in static body position. Participants engaged in an exogenous or endogenous response task while in a seated position, while lying in a prone position, and while in a prone position with their head down and neck flexed (HDNF). An attenuation of inhibition and facilitation effects during the exogenous task was observed in the HDNF position. However, responses to the cues remained similar in the endogenous task, irrespective of body position. The results reveal a potential dissociation between reflexive and volitional orienting of visual attention that is dependent on vestibular inputs.

Investigating the autonomic nervous system and cognitive functions as potential mediators of an association between cardiovascular disease and driving performance.

Cardiovascular disease (CVD) impacts the autonomic nervous system and cognitive functions related to activities of daily living, including driving an automobile. Although CVD has been linked to unsafe driving, mechanisms underlying this relationship remain elusive. The aim of this study was to examine the role of cognitive functions and the autonomic nervous system as potential mediators of driving performance. Nineteen individuals having recently suffered a cardiac event and 16 individuals with no history of CVD completed a simulated drive using a STISIM simulator to assess driving performance. Heart rate was recorded throughout testing using a Polar RS800CX heart rate monitor, and measures of executive, orienting, and alerting functions were obtained through the Attention Network Test. We used the Baron and Kenny analysis method to assess potential mediating effects of the relationship between CVD and driving performance. Executive function was the only potential mediator investigated to be associated with driving (p < 0.01) and CVD (p < 0.05); however, it did not appear to play a mediating role (p = 0.28). These results suggest that individuals with CVD exhibit decrements in complex cognitive tasks such as driving and that further research is needed to better understand the mechanisms underlying this relationship.

Physiological responses to simulated and on-road driving.

Driving simulators have become an increasingly popular tool to study and assess drivers. Physiological measurements not only provide an important index of an individual's presence in the virtual environment, but they also permit us to compare simulated and on-road experiences. However, at this point, few studies examining the ecological validity of simulated driving have included physiological variables. In a first study, we embedded three surprising events into a typical simulated road circuit. The first event consisted of a car pulling out suddenly from the shoulder of the road, while the remaining two events consisted of a green traffic light changing to amber as the driver approached the intersection. We noted statistically significant elevations in the mean heart rate (MHR) response to virtual events of about 4beats per minute (bpm) during the 15s immediately following the events. In a second study, we directly compared heart rate, oxygen consumption (VO(2)), and mean ventilation (MV(E)) responses to similar simulated and on-road drives. The change in physiological variables from baseline to driving was similar between simulated and on-road conditions, and a very strong correlation between simulated and on-road driving values for MV(E) (r=0.90) was observed. MHR and maximum heart rate (HR(max)) were nonetheless significantly higher during on-road drives. These studies suggest that the level of immersion of a fixed base simulator is great enough to elicit presence, and achieve both relative and absolute validity for certain physiological parameters. Nonetheless, the absolute responses between virtual and real world experiences remain different. For both research and evaluation purposes, it is critical that we better understand the impact of the driver's perceived level of risk or difficulty during simulation on their driving behaviour and physiological responses.

Impact of wall filter selection on the detection of vasomotor changes in the brachial artery: a pilot study.

During Doppler ultrasound assessment of blood flow, a wall filter is used to reduce or eliminate high-amplitude, low-velocity signals from the vessel wall and the surrounding tissue. This study investigated the impact of a range of wall filters (22 Hz, 75 Hz, 128 Hz, and 252 Hz) on the accuracy of forearm blood flow monitoring during the sympathoexcitatory application of lower body negative pressure, when peripheral blood flow may decrease substantially. The 252 Hz filter eliminated diastolic flow in 4 of 10 participants. In the remaining participants, the 252 Hz filter minimized the sensitivity of the pulsatility index. The interpretation of physiological responses could ultimately be compromised by using filters beyond 128 Hz.

Glycogen depletion of human skeletal muscle fibers in response to high-frequency electrical stimulation.

The purpose of the present study was to evaluate the pattern of change in muscular glycogen content in response to high-frequency electrical stimulation (HFES). Muscle biopsies were taken from the vastus lateralis muscle of 7 healthy young men before, 15 min after, and 30 min after electrical stimulation delivered at a 50-Hz frequency (15 s on, 45 s off) at an intensity of 100 mA. The glycogen content of type I, IIA, and IIB muscle fibres was evaluated using microphotometry of periodic acid Schiff (PAS) stained fibres. After 15 min of electrical stimulation, the glycogen content in type I, IIA, and IIB muscle fibres significantly decreased from 113 +/- 10 (mean +/- SE) to 103 +/- 10 (p < or = 0.05), 129 +/- 9 to 102 +/- 12 (p < or = 0.01), and 118 +/- 8 to 90 +/- 13 (p < or = 0.01) arbitrary relative units, respectively. No further decrement in glycogen content was observed in all three fibre types following an additional 15 min of HFES. In addition, isometric force decreased by approximately 50%, from 125.9 +/- 20.0 N to 64.2 +/- 7.7 N (p < or = 0.01), during the first 15 contractions. No further decrease in isometric force was observed following an additional 15 contractions of HFES. These results reveal that significant reductions in isometric force of knee extensor muscles and glycogen content of all human skeletal muscle fibre types in vastus lateralis muscle are observable after 15 min of neuromuscular high-frequency transcutaneous electrical stimulation.