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PubMed1999

Myocardial high-energy phosphate metabolism in patients with stable chronic dilated cardiomyopathy under a dobutamine-induced prolonged mild workload.

BACKGROUND: The myocardial phosphocreatine (PCr) to beta-adenosine triphosphate ratio measured by phosphorus 31 nuclear magnetic resonance spectroscopy, which is analogous to energy reserve, is one of the important clinical predictors in patients with dilated cardiomyopathy (DCM). However, it may vary with the cardiac workload. METHOD: The myocardial PCr to beta-adenosine triphosphate ratio was measured before and during a 5 and 10 microgram/kg/min infusion of dobutamine in 7 patients with DCM and in 8 normal patients. Dobutamine infusion was kept constant for 50 minutes in each stage. Myocardial contractility and ventricular size were determined by echocardiography with the same protocol. RESULTS: This ratio was unchanged from 1.5 +/- 0.4 to 1.8 +/- 0.6 in the low-dose stage and stable (1.7 +/- 0.3) in the high-dose stage in patients with DCM. The heart rate and the mean rate of circumferential fiber shortening increased dose dependently both in patients with DCM and in patients without. CONCLUSION: These results demonstrate that constant loading of dobutamine for hours is tolerated without deterioration of myocardial metabolic function by patients with nonischemic DCM. We concluded that the high-energy phosphate metabolism of stable patients with cardiomyopathy is stable if the workload is temporary and weak. This implies the possibility that mild exercise can be tolerated in patients with heart failure.

Adenosine Triphosphate↗

PubMed1998

Effect of percutaneous transvenous mitral commissurotomy on postexercise breathlessness as determined by ventilation during recovery from constant workload exercise.

We evaluated the effect of percutaneous transvenous mitral commissurotomy (PTMC) on ventilatory variables and dyspnea during recovery from a 6-minute submaximal constant workload exercise, and showed that the decrease in postexercise ventilation after PTMC was closely related to improvement in postexercise dyspnea after PTMC. Ventilation during recovery from submaximal constant workload exercise is related to postexercise breathlessness and can be used to assess the effectiveness of therapeutic interventions.

Adult↗

PubMed2002

The stimulation of heart glycolysis by increased workload does not require AMP-activated protein kinase but a wortmannin-sensitive mechanism.

Increasing heart workload stimulates glycolysis by enhancing glucose transport and fructose-2,6-bisphosphate (Fru-2,6-P(2)), the latter resulting from 6-phosphofructo-2-kinase (PFK-2) activation. Here, we investigated whether adenosine monophosphate (AMP)-activated protein kinase (AMPK) mediates PFK-2 activation in hearts submitted to increased workload. When heart work was increased, PFK-2 activity, Fru-2,6-P(2) content and glycolysis increased, whereas the AMP:adenosine triphosphate (ATP) and phosphocreatine/creatine (PCr:Cr) ratios, and AMPK activity remained unchanged. Wortmannin, the well-known phosphatidylinositol-3-kinase inhibitor, blocked the activation of protein kinase B and the increase in glycolysis and Fru-2,6-P(2) content induced by increased work. Therefore, the control of heart glycolysis by contraction differs from that in skeletal muscle where AMPK is involved.

AMP-Activated Protein Kinases↗

PubMed2001

Auditory probe sensitivity to mental workload changes - an event-related potential study.

The goal of this study was to explore the utility of parameters of ERPs for assessment of mental workload during performance of complex tasks. In addition to a baseline auditory oddball task, 15 healthy adult volunteers performed gauge monitoring (Gauge) and mental arithmetic (Math) separately and together. Throughout the task performance three types of auditory stimuli were presented as probes, i.e. 80% 1000 Hz tones, 10% 2000 Hz tones and 10% novel sounds. The ERP components N1 and P3 were analysed, which are assumed to reflect perceptive and central processing resources. The results interpreted in the framework of capacity theory indicate high demand on processing resources already during separate performance of both tasks Gauge or Math. During simultaneous performance the workload on average exceeded the limits of processing capacity: the performance data impaired significantly. The ERP measures N1 and P3 were confirmed in their sensitivity and diagnosticity. By using novel sounds as probes with involuntary attention-capturing properties, one might overcome a problem of the irrelevant probe technique, i.e. whether the operator spends his spare capacity for processing of the irrelevant probes.

Acoustic Stimulation↗

PubMed2001

Multivariate workload evaluation combining physiological and subjective measures.

This paper suggests a way to integrate different parameters into one index and results obtained by a newly developed index. The multivariate workload evaluation index, which integrates physiological parameters and one subjective parameter through Principle Components Analysis, was proposed to characterize task specific responses and individual differences in response patterns to mental tasks. Three different types of mental tasks were performed by 12 male participants. Heart rate variability, finger plethysmogram amplitude, and perspiration were used as physiological parameters. Three subscales, mental demand, temporal demand and effort out of six subscales in the NASA-Task Load Index were used as subjective scores. These parameters were standardized within each participant and then combined. It was possible to assess workload using this method from two different aspects, i.e. physiological and subjective, simultaneously.

Adolescent↗

PubMed1996

Relations among memory performance, mental workload and cardiovascular responses.

The levels of processing paradigm has been a powerful research framework in the study of memory for close to a quarter century. However, an objective index of depth of processing is still lacking. Two experiments using lists of words, presented to male subjects, wee performed to compare the effects of depth of processing, rate of presentation, and task incentive on recognition memory performance, self-reported workload, and cardiovascular responding. Memory performance results from the two experiments demonstrated higher recognition levels associated with deeper processing and slower presentation rates. Deeply encoded items were associated with faster recognition latencies. Self-reported workload levels were higher for deeper processing and faster presentation rates. Cardiovascular responses were generally amplified with the addition of a task incentive. Increased blood pressure was associated with faster presentation rates. Increased heart rate and decreased T-wave amplitude (i.e., increased sympathetic activity) were uniquely associated with the deep encoding of information presented at the fastest rate. This particular encoding condition was associated with increased recognition levels. Deeply encoded items were associated with increased suppression of heart rate variability during recognition. This combination of behavioral and cardiovascular measures may provide the basis for an objective index of depth of processing.

Adult↗

PubMed2003

Effects of mental workload and caffeine on catecholamines and blood pressure compared to performance variations.

Caffeine is characterised as a central nervous system stimulant, also affecting metabolic and cardiovascular functions. A number of studies have demonstrated an effect of caffeine on the excretion of catecholamines and their metabolites. Urinary epinephrine and norepinephrine have been shown to increase after caffeine administration. Similar trends were observed in our study in adrenaline (ADR) and noradrenaline (NORADR) levels and additionally a dose dependent effect of caffeine. The effect of caffeine on cognitive performance, blood pressure, and catecholamines was tested under resting conditions and under mental workload. Each subject performed the test after oral administration of 1 cup and then 3 cups of coffee. Root mean square error (RMSE) for the tracking task was continuously monitored. Blood pressure was also recorded before and after each stage of the experiment. Catecholamines were collected and measured for three different conditions as: at rest, after mental stress alone, after one dose of caffeine under stress, and after triple dose of caffeine under stress. Comparison of the performance of each stage with the resting conditions revealed statistically significant differences between group of smokers/coffee drinkers compared with the other two groups of non-coffee drinkers/non-smokers and non-smokers/coffee drinkers. There was no statistically significant difference between the last two groups. There was an increase of urine adrenaline with 1 cup of coffee and statistically significant increase of urine noradrenaline. Both catecholamines were significantly increased with triple dose of caffeine. Mental workload increased catecholamines. There was a dose dependent effect of caffeine on catecholamines.

Adolescent↗

PubMed1989

Variability in nursing workload within CMGs (case mix groups).

This study examines the differences in workload estimates of three patient classification systems in nursing, within selected Case Mix Groups (CMGs). The amount of variation explained by selected patient-specific variables within CMGs on average nursing workload by each system is also analyzed. Results show that, when patient classification data are used to explain nursing time within the Diagnosis Related Group (DRG) context, absolute hours of care estimates of the various systems may not be equivalent. This inequality may result in biased budget review practices unless relational statements are developed between systems.

Canada↗

PubMed1997

Exercise dynamics at submaximal workloads in patients with chronic heart failure.

BACKGROUND: The aims of this study were to analyze the relationship between exercise at self-selected work loads and peak exercise performance in patients with chronic heart failure and to analyze possible relationships between gait pattern and exercise performance and ventilatory response to exercise in chronic heart failure. METHODS AND RESULTS: Twelve patients with stable chronic heart failure and 10 age- and build-matched control subjects undertook symptom-limited maximal exercise testing with metabolic gas exchange measurements to determine peak oxygen consumption (VO2) and the slope of the relationship between ventilation and carbon dioxide production (VE/VCO2 slope). Respiratory rate was also determined. Self-selected walking pace and cadence (steps per minute) were determined. Metabolic gas exchange analysis was repeated at matched low-level exercise and at self-selected walking pace. Self-selected exercise was at a lower speed for patients than control subjects (1.28 [0.22] vs 1.43 [0.19] m s-1), representing a similar proportion of peak oxygen consumption (63.6 [19.3]% vs 56.7 [25.4]%). There was a relationship between peak VO2 and VO2 at self-selected workload (r = .55, P < .001) and self-selected walking velocity (r = .58, P < .005). Gait analysis demonstrated that the reduction in self-selected velocity in heart failure patients was due to a reduced cadence (101.5 [8.7] steps/min vs 110.2 [9.1] steps/min, P < .01), not a reduction in stride length. There was a negative relationship between VE/VCO2 slope and self-selected cadence (r = -.68, P < .001) and a negative correlation between respiratory rate and cadence at self-selected workload (r = -.6, P < .005). CONCLUSIONS: Self-selected walking speed is at the same proportion of peak oxygen consumption in patients with heart failure as compared with control subjects, but a lower absolute level. Patients have the same stride length as normal control subjects. Ventilation is increased in patients, but there is no direct relationship between ventilation and gait.

Exercise Test↗

PubMed1989

Effects of daily workload on subsequent behavior during marital interaction: the roles of social withdrawal and spouse support.

This article examines daily variability in 2 marital behaviors, social withdrawal and the expression of anger, as a function of daily taskload at work. Thirty-three air traffic controllers (ATCs) and 27 wives completed surveys on 3 consecutive days. Subjective and objective indicators of daily workload (air traffic volume and visibility at the airport) were related to the couples' descriptions of the ATCs' behavior after work. Despite a positive association between withdrawal and anger, workload seemed to influence these 2 behaviors in opposite ways. On high spouse-support evenings, work overload was associated with increased social withdrawal and less expression of anger. Social withdrawal may help an aroused individual return to a baseline emotional and physiological state. By facilitating their stressed partner's social withdrawal, supportive spouses may buffer the effects of minor daily stressors.

Anger↗

PubMed2003

Mental workload while driving: effects on visual search, discrimination, and decision making.

The effects of mental workload on visual search and decision making were studied in real traffic conditions with 12 participants who drove an instrumented car. Mental workload was manipulated by having participants perform several mental tasks while driving. A simultaneous visual-detection and discrimination test was used as performance criteria. Mental tasks produced spatial gaze concentration and visual-detection impairment, although no tunnel vision occurred. According to ocular behavior analysis, this impairment was due to late detection and poor identification more than to response selection. Verbal acquisition tasks were innocuous compared with production tasks, and complex conversations, whether by phone or with a passenger, are dangerous for road safety.

Adult↗

PubMed2000

Dyspepsia workload in urban general practice and implications of the British Society of Gastroenterology Dyspepsia guidelines (1996).

AIM: To define the characteristics of patients consulting with active dyspeptic symptoms in urban general practice, and to consider the implications of applying the British Society of Gastroenterology Dyspepsia management guidelines. DESIGN: Prospective observational study over a period of 12 months. SETTING: Two multipartner, two-centre general practices in the City of Leeds (UK) with a combined target population of 11 011 registered patients. SUBJECTS: A total of 340 patients consulting with active dyspeptic symptoms (52% male; mean age 53 years, range 16-89 years). RESULTS: Of the practice population, 3% consulted with dyspepsia (first-time consulter: 19%; previous consulter not yet investigated: 30%; previously investigated: 51%). Of 168 undiagnosed patients, 43% had upper abdominal pain (dysmotility-like symptoms in 42%), 35% had reflux symptoms, 22% had mixed symptoms, 12% had 'alarm' symptoms and 18% had a history of NSAID use. Patients < 45 years old with simple dyspepsia accounted for 32% of undiagnosed cases. A fifth of the workload was in dealing with undiagnosed dyspeptics over 45 years old. One per cent of the population would require endoscopy if all undiagnosed cases either > 45 years or with complicated dyspepsia were investigated. Of 172 previously investigated patients, 29% had negative tests, 25% had 'minor' findings, and 45% had evidence of acid-peptic disease. Patients with duodenal ulcer disease accounted for 12% of the total workload. CONCLUSIONS: A knowledge of the characteristics of patients consulting with dyspepsia in primary care should allow the adaptation of guidelines, to ensure advice is relevant to local case mix and compatible with local resources.

Adolescent↗

PubMed2000

Cholecystectomy: does subspecialization alter workload?

AIMS: Cholecystectomy is a common operation. This study reviewed the changes in workload and practice in a teaching hospital over a 4-year period, during which a hepatobiliary subspecialist unit was developed. METHODS: Computerized demographic data, and details of operations and inpatient events were reviewed for all patients undergoing cholecystectomy in a single teaching hospital from 1993 to 1997. For statistical analysis the consultants were grouped into those with a hepatobiliary interest (n = 3) and those with other primary interests (n = 6); and the workload for the first 12 months of the study was compared with that of the last 12-month period. RESULTS: Between April 1993 and April 1997, 1121 cholecystectomies were performed, of which 75 were excluded because they were performed with other simultaneous procedures. Of the remaining operations, 911 involved cholecystectomy alone (mean patient age 52. 9 years), and 135 (12.9 per cent) comprised cholecystectomy with exploration of the common bile duct (ECBD) (mean age 60.1 years). Between the first and last years studied, the rate of ECBD rose significantly from 7.4 to 14.9 per cent (P < 0.01, chi2 test), and the proportion of ECBD procedures being performed by hepatobiliary specialists rose from 31.6 to 52.7 per cent, but this was not statistically significant (P = 0.13). However, for cholecystectomy in the same period the proportion performed by hepatobiliary surgeons rose from 40.4 to 58.5 per cent, representing a highly significant trend (P < 0.001). Following cholecystectomy alone there was a significantly shorter stay associated with patients treated by hepatobiliary surgeons (P = 0.002, F test), although the median postoperative hospital stay was 2 days for both groups of surgeons (interquartile range 1-3 days for hepatobiliary and 1-4 days for non-hepatobiliary surgeons). CONCLUSIONS: Although cholecystectomy is not viewed as a specialist procedure, the trend in this teaching hospital reveals a steady increase in the proportion of cholecystectomies being performed by teams with a biliary interest. The data indicate that this practice is associated with a shorter hospital stay.

Journal Article↗

PubMed2000

Exhaled nitric oxide during incremental and constant workload exercise in chronic cardiac failure.

BACKGROUND: Nitric oxide (NO) is present in exhaled breath and produced by the pulmonary vascular endothelium as a potent vasodilator. Exercise is normally associated with pulmonary vasodilatation and a decrease in pulmonary vascular resistance to accommodate the increase in cardiac output. If production of NO is impaired in patients with chronic congestive cardiac failure (CCF), this might contribute to their exercise intolerance. PATIENTS AND METHODS: We quantified NO production (V NO) in 12 patients with chronic stable CCF and 12 controls, at rest and during incremental cardiopulmonary exercise on a treadmill, and at a later date during constant workload exercise. RESULTS: Patients had reduced V NO compared with controls during incremental exercise [381 (180) vs. 777 (275) nL min-1; mean (SD); P < 0.0001] but at constant workload V NO was similar between the two groups [353 (124) vs. 389 (189) nL min-1; P = 0.25]. Plasma levels of nitrate, the stable end-product of NO production, were significantly higher in patients [resting value 46.1 (21.6) vs. 23.0 (10.0) microM; P = 0.004] and were not influenced by exercise. CONCLUSION: Impaired NO-mediated pulmonary vasodilatation does not appear to contribute to exercise limitation in CCF. Alternatively, the lower NO production observed during maximal exercise in the patient group compared with controls may reflect a reduced incremental response of a system that is already abnormally activated in heart failure.

Aged↗

PubMed2002

Research into the workload and roles of oncology nurses within an outpatient oncology unit.

This project evaluated the roles and workload of Registered Nurses (RNs) within an outpatient Cancer Care Centre (CCC) of a tertiary referral hospital in Sydney, Australia. The research incorporated the two distinct areas of radiation oncology and haematology oncology. Patient throughput (incorporating clinic attendance and treatments) was known to have increased substantially since the centre opened in 1994. The nursing Full Time Equivalents (FTEs) for the CCC were determined when the centre opened with minimal change to the nursing establishment since then. Nursing staff perceived that their workload had increased substantially and that their roles had become more complex. Work sampling was conducted over a 3-month period and identified the range of nursing activities performed by the oncology outpatient nurse. The nurses were found to have a large administrative role while their nursing activities ranged from basic nursing tasks to more specialist activities including patient counseling and complex chemotherapy regimes.

Journal Article↗

PubMed2000

A workload survey of police surgeons in Darlington, UK showing recent changes and detailed work patterns in 1998.

This paper gives an accurate picture of the police surgeon workload in the town of Darlington for the year 1998, and is compared with a similar workload survey done 5 years ago in 1993. The number of cases seen in 1998 shows an increase of 142% compared with 5 years ago, and various explanations are given as to the possible causes of this significant change. The pattern of call-outs for the time of day and the busiest nights of the week clearly shows the peak demands for our services in the evenings and especially Friday and Saturday nights. The breakdown showing the reason for attendance indicates the significant rise in drug addicts seen with associated drug-driving assessments. Examination for CS spray are compared with a correspondingly small number of baton injuries and injuries to police officers. This type of information could be used to introduce police surgeon recruits to the pattern of work that awaits them. Planning and budget implications could be more accurately predicted, and the figures could be used to compare with other areas for those police surgeons who also keep records.

Journal Article↗

PubMed1976

[Assessment of radiologists workload in Scandinavia(author's transl)].

Experience in Sweden, Norway and Finland (University Clinic, Oulu) indicates that the points system instituted by the Scandinavian Association of Radiologists provides a satisfactory means of measuring radiologists' workload. A similar system for assessing radiographic technicians' workload is desirable.

Humans↗

PubMed2004

Workload demands in mountain bike racing.

This study aims at describing the workload demands during mountain bike races using direct power measurements, and to compare these data to power output and physiological findings from laboratory exercise tests. Power output (P, Watt) from 11 national team cyclists (9 male, 2 female) was registered continuously during 15 races using mobile crank dynamometers (SRM System). To evaluate the intensity of racing, incremental exercise tests with determination of P at aerobic and anaerobic thresholds (AT, IAT) and at exhaustion (MAX) were performed. Intensity zones were determined (zone 1 < AT; AT < zone 2 < IAT; IAT < zone 3 < MAX; zone 4 > MAX) and time spent during racing in these zones was calculated. Based on power output measurements P during racing was 246 +/- 12 W (male) and 193 +/- 1 W (female). P showed high variation throughout the race. In contrast heart rate (HR) was relatively stable during racing (male 177 +/- 6 bpm, female 172 +/- 7 bpm). 39 +/- 6 % of race time were spent in zone 1, 19 +/- 6 % in zone 2, 20 +/- 3 % in zone 3 and 22 +/- 6 % in zone 4. MTB races are characterized by a high oscillation in P with permanently elevated HR. A highly developed aerobic and anaerobic system is needed to sustain the high variation in workload.

Adult↗