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PubMed2004

Oxygen uptake-work rate relationship during two consecutive ramp exercise tests.

The performance of prior high intensity constant work rate (CWR) exercise significantly influences the gain of the fundamental oxygen uptake (VO2) response during subsequent high intensity CWR exercise. The purpose of the present study was to investigate whether equivalent effects could be elicited in the second of two bouts of exhaustive ramp exercise. We therefore hypothesised that a prior bout of exhaustive ramp exercise would increase the VO2-work rate (DeltaVO2/DeltaWR) slope during subsequent ramp exercise. Nine healthy males performed two ramp exercise tests to exhaustion on an electrically braked cycle ergometer separated by a 10-min period of cycling at 20 W. Pulmonary VO2 was measured breath-by-breath throughout both tests, and the mean response time (MRT) and the DeltaVO2/DeltaWR slope for exercise below the gas exchange threshold (GET) (S1), above the GET (S2), and over the S1 + S2 region (ST) were determined. Paired t-tests were used to analyse the data with significance accepted at p < 0.05. Blood [lactate] was higher at the onset of the second ramp test compared to the first (mean +/- SEM 1.2 +/- 0.1 vs. 6.2 +/- 0.7 mM; p < 0.01), but baseline VO2 was not significantly different between tests (0.93 +/- 0.05 vs. 0.99 +/- 0.06 L. min (-1)). The MRT (42 +/- 4 vs. 40 +/- 5 s) did not differ between tests, but the DeltaVO2/DeltaWR slope was steeper in the second ramp test for S2 (9.1 +/- 0.4 vs. 9.8 +/- 0.5 ml. min (-1). W (-1); p < 0.01) and ST (9.0 +/- 0.4 vs. 9.6 +/- 0.5 ml. min (-1). W (-1); p < 0.05). The demonstration that prior ramp exercise increases the DeltaVO2/DeltaWR slope during subsequent ramp exercise is consistent with the results of previous CWR studies and indicates that exercise economy is sensitive to the prior activity of the engaged muscles.

Adult↗
PubMed1999

Is there competition between breast-feeding and maternal employment?

Theory suggests that the decision to return to employment after childbirth and the decision to breast-feed may be jointly determined. We estimate models of simultaneous equations for two different aspects of the relationship between maternal employment and breast-feeding using 1993-1994 data from the U.S. Food and Drug Administration's Infant Feeding Practices Study. We first explore the simultaneous duration of breast-feeding and work leave following childbirth. We find that the duration of leave from work significantly affects the duration of breast-feeding, but the effect of breast-feeding on work leave is insignificant. We also estimate models of the daily hours of work and breast-feedings at infant ages 3 months and 6 months postpartum. At both times, the intensity of work effort significantly affects the intensity of breast-feeding, but the reverse is generally not found. Competition clearly exists between work and breast-feeding for many women in our sample.

Adult↗
PubMed1991

An evaluation of the preoperative information given to patients by intensive care nurses.

In many hospitals it is common practice for nurses working in intensive care units to visit patients on the ward when a stay in the intensive care unit is anticipated following elective surgery. The purpose of the preoperative visit is to minimise fear and anxiety by preparing patients for their admission by providing information about the unit, the equipment used and responding to any questions. However, although there is extensive evidence to support the advantages of information--giving prior to stressful events the author could find no evaluation of the type of information given by intensive care staff. The purpose of the study was three fold. Firstly to discover the type of information patients would like to receive. Secondly to use this data in compiling a booklet which could be used to supplement the preoperative visit. Thirdly to evaluate the contents of the booklet. Postoperatively 20 patients evaluated the booklet by means of a self-administered questionnaire. These were completed 48 h after their transfer from the unit. Overall patients were satisfied with the information contained in the booklet but felt they required additional advice about their proposed surgery and needed more time to absorb the information they had been given.

Consumer Behavior↗
PubMed1997

Interval training in patients with severe chronic heart failure: analysis and recommendations for exercise procedures.

This study analyzes a new exercise training procedure, which includes interval exercise training on cycle ergometer (IntCT) (30-s work phases/60-s recovery phases) and on treadmill (60-s work and recovery phases each). Training was applied for 3 wk in 18 patients with severe chronic heart failure (CHF) ((mean +/- SEM) age 52 +/- 2 yr, ejection fraction 21 +/- 1%). Peak VO2 was increased from 12.2 +/- 0.7 to 14.6 +/- 0.7 ml-kg-1 min-1 owing to training (P < 0.001). A specific steep ramp test (work rate increments 25 W.10 s-1) was developed to derive exercise intensity for work phases in IntCT, which was 50% of the maximum work rate achieved. Steep ramp test was performed at the start of the study to determine the initial training work rate, then weekly to readjust it. Since the maximum work rate achieved from this test increased weekly (144 +/- 10 W -->172 +/- 10 W-->200 +/- 11 W; P < 0.001), the training work rate also increased (72 +/- 4 W-->86 +/- 6 W-->100 +/- 7 W; P < 0.001). Physical responses to IntCT were measured. There was no significant change in heart rate, blood pressure, and ratings of perceived exertion (RPE) using a Borg Scale between the first and the third week of training (heart rate 88 +/- 3 b.min-1; blood pressure 115 +/- 4/80 +/- 2 mm Hg; leg fatigue 12 +/- 1; dyspnea 10 +/- 1). Mean lactate concentration (1.70 +/- 0.09 mmol-1-1) indicated an overall aerobic range of training intensity. When compared with the commonly used intensity level of 75% peak VO2 from an ordinary ramp test (work rate increments 12.5 W.min-1), the performed training work rate was more than doubled (240%; P < 0.0001) while cardiac stress was lower (86%; P < 0.01). Values of norepinephrine and epinephrine as well as of RPE corresponded to those measured at 75% peak VO2. Interval exercise training is thus recommended for selected patients with CHF as it allows intense exercise stimuli on peripheral muscles with minimal cardiac strain. Using a steep ramp test, training work rate can be determined and readjusted weekly during initial training period.

Bicycling↗
PubMed2000

Applying the resource-based relative value scale to the Emory angioplasty versus surgery trial.

The resource-based relative value scale developed for use in the Medicare fee schedule can also be very useful in profiling and comparing physicians' cardiovascular utilization across different medical activities. This article applies relative value units (RVUs) to data from the Emory Angioplasty versus Surgery Trial. The Emory Angioplasty versus Surgery Trial was a randomized clinical trial to determine the efficacy of percutaneous transluminal coronary angioplasty (PTCA) versus coronary artery bypass surgery (CABG). All physician services in the clinical trial provided to 2 groups of patients--those undergoing CABG and those receiving PTCA-over the course of 4 years were assigned physician work RVUs (representing the intensity of physician work required) and total RVUs (representing both the intensity and practice costs). Physician charges were also compiled. These data were used to profile and compare physician services to the 2 groups of patients by type of service, distribution over time, and clinical department. Comparisons based on RVUs contrast sharply with differences based on charges. Mean physician charges, in 1996 dollars, were $27,158 for CABG patients and $21,491 for PTCA patients, a 26% difference (p <0.001). Physician work RVUs generated an 18.3% difference (p = <0.001). Using total RVUs, the difference between the 2 groups was 3.3% (p = 0.249). Resource-based relative value weights are a valuable tool for analyzing and comparing physicians' use of cardiovascular resource. The results suggest that conclusions about physician resource utilization based on physician charges should be carefully evaluated. When possible, physician work RVUs should be compiled and evaluated along with physician charges.

Angina Pectoris↗
PubMed1992

Role of O2 in regulating tissue respiration in dog muscle working in situ.

This study was designed to investigate the role of tissue oxygenation in some of the factors that are thought to regulate muscle respiration and metabolism. Tissue oxygenation was altered by reductions in O2 delivery (muscle blood flow x arterial O2 content), induced by decreases in arterial PO2 (PaO2). O2 uptake (VO2) was measured in isolated in situ canine gastrocnemius at rest and while working at two stimulation intensities (isometric tetanic contractions at 0.5 and 1 contractions/s) on three separate occasions, with only the level of PaO2 (78, 30, and 21 Torr) being different for each occasion. Muscle blood flow was held constant (pump perfusion) at each work intensity for the three different levels of PaO2. Muscle biopsies were obtained at the end of each rest and work period. Muscle VO2 was significantly less (P less than 0.05) at both stimulation intensities for the hypoxemic conditions, whereas [ATP] was reduced only during the highest work intensity during both hypoxemic conditions (31% reduction at 21 Torr PaO2 and 17% at 30 Torr). For each level of PaO2, the relationships between the changes that occurred in VO2 and levels of phosphocreatine, ADP, and ATP/ADP.P(i) as the stimulation intensity was increased were significantly correlated; however, the slopes and intercepts of these lines were significantly different for each PaO2. Thus a greater change in any of the proposed regulators of tissue respiration (e.g., phosphocreatine, ADP) was required to achieve a given VO2 as PaO2 was decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1994

Does nurse turnover mean nurse wastage in intensive care units.

It has been claimed that the turnover rate of nurses working in Intensive Care Units (ICUs) is higher than in other areas of nursing; very little statistical evidence was found to support this claim. A questionnaire was designed to discover the reasons for nurse turnover among intensive care nurses. 45 nurses who had left the three ICUs of a large teaching hospital took part in the survey providing quantitative and qualitative data. High levels of dissatisfaction were found for career development, pay and clinical regrading, these being the main cause of turnover among the nurses who responded. Other causes were moving to another geographical area and the need for flexible hours. These findings can partly be explained by role conflict.

Adult↗
PubMed2003

Intensity and challenge as an aspect of work satisfaction in an urban emergency room.

This phenomenological study examined the lived experience of expert emergency room nurses in order to describe their sources of work satisfaction. An interpretive analysis was completed of interviews with 13 nurses in addition to observations of their practice. Experienced nurses described appreciating the challenge of working with complex patients, valuing the unpredictable nature of their work, and enjoying the intensity and fast pace of the emergency room as it helped them to focus. Because this appreciation for intensity and challenge was also an aspect of the nurses' personal lives, nurse managers should consider to what extent the personality characteristics of nurses interviewing for new positions match the unit culture. Scheduling interviews on the unit itself may facilitate nurses obtaining a reality-based understanding of the unit culture prior to beginning employment.

Academic Medical Centers↗
PubMed2003

Management of patients in the intensive care unit: comparison via work sampling analysis of an acute care nurse practitioner and physicians in training.

BACKGROUND: Little is known about aspects of practice that differ between acute care nurse practitioners and physicians that might affect patients' outcomes. OBJECTIVE: To determine if time spent in work activities differs between an acute care nurse practitioner and physicians in training (pulmonary/critical care fellows) managing patients' care in a step-down medical intensive care unit. METHODS: Work sampling techniques were used to collect data when the nurse practitioner had 6 months' or less experience in the role (T1), after the nurse practitioner had 12 months' experience in the role (T2), and when physicians in training provided care on a rotational schedule (nurse practitioner not present, T3). These data were used to estimate the time spent in direct management of patients, coordination of care, and nonunit activities. RESULTS: Results for T1 and T2 were similar. When T2 and T3 were compared, the nurse practitioner and the physicians in training spent approximately half their time in activities directly related to management of patients (40% vs 44%, not significantly different). The nurse practitioner spent more time in activities related to coordination of care (45% vs 18%; P < .001) and less time in nonunit activities (15% vs 37%; P < .001). CONCLUSION: The nurse practitioner and the physicians in training spent a similar proportion of time performing required tasks. Because of training requirements, physicians spent more time than the nurse practitioner in nonunit activities. Conversely, the nurse practitioner spent more time interacting with patients and patients' families and collaborating with health team members.

Acute Disease↗
PubMed1998

A comparison of the effects of patients' pain on nurses working in burns and neonatal intensive care units.

Nurses are more likely than other health professionals to be exposed to individuals who suffer severe pain for extended periods of time. Such exposure is likely to arouse emotional distress which not only has implications for their occupational health but may interfere with their ability to manage pain effectively. This study compared the emotional reactions to their patients' pain, of nurses who were exposed to patients with severe and obvious pain (nurses working in burns units) and nurses whose patients' pain is uncertain because they are unable to communicate (nurses working in neonatal intensive care units). The results showed that pain generated greater anxiety in nurses caring for patients with severe burns, but that they also demonstrated a greater sense of personal competence and control over the management of their patients' pain. The findings also showed that when dealing with patients' pain the morale of nurses was linked to: (a) perceived challenges to their images of themselves as alleviators of pain; (b) the extent to which their sense of personal vulnerability was aroused by contact with patients experiencing severe pain; (c) their beliefs about their ability to assess patients' pain; and (d) the quality of their professional relationships with the medical staff who controlled the most powerful forms of pain relief.

Anxiety↗
PubMed2000

Laser-activated voltammetry: measurement of the diffusion coefficients of electropassivating species. Application to pyrrole and phenol in aqueous solution

Clean electrode surfaces can be achieved during the electrolysis of otherwise passivating species in aqueous and other solutions by means of surface ablation using a 10-Hz pulsed Nd:YAG 532-nm laser. This ability to remove passivating electrolytically generated layers on glassy carbon and platinum electrodes is shown first by an investigation of the stripping peaks formed from the electrogeneration of the neutral forms of methyl viologen and heptyl viologen during reduction in aqueous solution of dications. Next, laser ablation was conducted under well-defined hydrodynamic conditions using a channel flow cell to identify laser power thresholds below which transport-limited currents could be seen, which were in quantitative agreement with those expected in the absence of irradiation. Levich plots recorded in the channel flow cell for K4Fe(CN)6 at glassy carbon and platinum electrodes showed such agreement for laser intensities lower than 0.17 and 0.65 W cm(-2), respectively. Working at intensities below these thresholds, steady-state voltammetry was observed for the oxidation of both phenol and pyrrole at glassy carbon and platinum electrodes, respectively, in aqueous solution. The diffusion coefficients of these two species were then measured under hydrodynamic conditions using laser ablation voltammetry to continuously clean the surface. Diffusion coefficients were inferred using the Levich equation. The result for phenol at a pH of 12 in aqueous solution was 0.9 (+/-0.1) x 10(-5) cm2 s(-1), which is in good agreement with an independent nonelectrochemical method. The diffusion coefficient of pyrrole in aqueous solution was similarly evaluated as 1.25 (+/-0.1) x 10(-5) cm2 s(-1).

Journal Article↗
PubMed2006

Measuring screening intensity in case-control studies of the efficacy of mammography.

Of great interest in studies of screening for breast cancer is the relative efficacy of different screening frequencies (intensities). Prior work has suggested that estimates of the association between screening intensity and outcome in case-control studies would not produce valid results and that only binary indicators (no screens vs. one or more) of exposure can be used. Using case-control studies drawn from simulated cohorts of 30,000-40,000 women, the authors found that biases demonstrated in prior studies can be explained by 1) misclassification of true exposure groups by observed screening history, and 2) differential exposure misclassification of cases and controls. Binary as well as ordered categorical and interval measures can be biased unless they account for misclassification. By combining measurements of screening history from multiple periods of observation of varying lengths and using repeated-measures logistic regression models, the effect of screening intensity can be estimated in the presence of misclassification. Assessing the effect of screening intensity in case-control studies of mammography is possible if principles and methods for misclassification and measurement error guide the analysis.

Breast Neoplasms↗
PubMed1996

The effect of work activity in pregnancy on the risk of fetal growth retardation.

BACKGROUND: The relationship between physical activity at work and risk of fetal growth restriction is controversial. For the most part, previous studies investigated the effect of work activity on birthweight alone. We evaluated the impact of type of occupation and physical effort at work on the risk of ultrasonographically confirmed fetal growth retardation among nulliparous women. METHODS: We compared the characteristics of work and the intensity of occupational fatigue (work posture, weekly working hours, physical effort at work) in 349 patients with ultrasonographically confirmed fetal growth retardation and 698 control pregnancies with appropriate fetal growth. Physical demands at work were evaluated by interview at birth. Logistic regression analysis was used to evaluate the association of employment status, type of occupation, and intensity of occupational fatigue with the risk of fetal growth retardation, correcting for potential confounders (maternal age, pre-pregnancy body mass index, mean weight gain in pregnancy, education, partner's social status, smoking in pregnancy, alcohol use, illicit drug use, time of stopping work, and hypertension). RESULTS: After adjusting for confounding, the risk of fetal growth retardation was similar between unemployed and formally employed women at the beginning of pregnancy (OR = 1.26; 95% confidence interval = 0.86 - 1.83). However, manual workers were at slightly higher risk of IUGR than not formally employed women (OR = 1.81; 95% CI = 1.15 - 2.85). Among formally employed women, standing or walking at work, and working > or = 30 hours a week were not significantly associated with IUGR. Finally, the risk of IUGR was significantly higher (OR = 2.46; 95% CI = 1.36 - 4.21) among women reporting moderate-to-heavy as compared to light physical effort at work. CONCLUSION: Formal employment at the beginning of pregnancy is not associated with an increased risk of IUGR. However, moderate-to-heavy physical effort at work seems to increase the risk of sonographically confirmed fetal growth retardation.

Female↗
PubMed1997

Staff stress on the intensive care unit: a comparison of doctors and nurses.

Working on an intensive care unit is perceived as stressful. This study investigated occupational stress in staff working on an intensive care unit using the occupational stress indicator. Questionnaires were given to all intensive care staff; the replies were then analysed and compared with normative data. The response rate was 62%. Intensive care unit staff found aspects of their job relating to career and achievement and organisational design and structure more stressful than a normal working population. Their coping strategies differ but the only significantly different measure of adverse outcome was related to personal relationships at work. The job itself was not found to be a significant source of stress. Nursing staff have different sources of stress from medical staff and individuals with partners or children are relatively protected from stress.

Adaptation, Psychological↗
PubMed1979

[Adrenergic response to intense muscular activity in sedentary subjects as a function of emotivity and training].

Seven male sedentary human subjects were studied during intense muscular work (80% of maximal oxygen uptake) performed either for 15 min or until exhaustion (mean duration: 47 +/- 2 min). Plasma catecholamines were estimated before and after the experiment by means of an original fluorimetric assay. Epinephrine or norepinephrine were individually isolated from plasma and assayed in single extracts by a highly sensitive fluorimetric method. Epinephrine and norepinephrine levels as low as 15 ng per liter were detectable by this procedure in human plasma. The adrenergic pattern was found to be greatly different from one subject to another and related to emotivity: the effect of this factor was revealed by the predominance of epinephrine in plasma at rest or under exercise (ratio NA/A less than 1). In nonemotive subjects (ratio NA/A greater than 1 at rest) plasma epinephrine and norepinephrine increased progressively during exercise. Increments after exercise were higher for norepinephrine changes; however, the fact that epinephrine concentrations correlated significantly with norepinephrine suggests a simulataneous and coordinated stimulation of adrenal glands and orthosympathetic nervous system. In emotive subjects (ratio NA/A less than 1 at rest) the apprehension of muscular work promoted a difference in catecholamine responses: norepinephrine release was not affected by subject's anxiety, while epinephrine secretion, already elevated before the test, reached a high degree of magnitude in the first minutes of muscular work, remaining nearly constant until exhaustion. Physical training of nonemotive subjects, during 2 months with two intense exercises by a week, reduced strongly norepinephrine release after exhaustive muscular work. In the same conditions, the adrenal-medullary response was not significantly modified when compared with untrained subjects. Our results suggest that the adrenergic behaviour during exercise is a function of effort intensity to be supplied; catecholamines seem to be important factors in regulating body homeostasy during muscular work in man. In addition, emotive subjects exhibit amplified adrenal-medullary response, which may be related to psychological stimuli.

Anxiety↗
PubMed1991

Legal and ethical problems in intensive care units.

The intent of this article is to increase the awareness of physicians working in intensive care units as to their legal and ethical responsibilities, and the potential for serious harm they can do to patients with the inevitable malpractice law suit if patient damage does occur. This article also suggests some defences in the event that physicians get involved in the legal cobweb.

Advance Directives↗
PubMed2004

The nature of long-term care nursing work.

Data from a pilot study on the nature of nursing work in long-term care (LTC) facilities are compared with data on nursing work in intensive care units (ICUs). The comparison suggests that the LTC nursing work environment is a complex, demanding, and interesting one that is different from, not less than, nursing work in acute care environments. The data also suggests that nursing educators and researchers should reconsider LTC nursing work environments. Long-term care nursing offers an ideal, relatively controlled environment for research on what nursing work is and how nursing interventions affect patient outcomes. Long-term care nurses, whose daily work has always involved working with a variety of professional and unlicensed staff members, can serve as models for delegation and interpersonal skills. Finally, the LTC setting offers the ideal environment for clinical sites in connection with the proposed curriculum changes in end-of-life care for patients and their families.

Aged↗
PubMed2006

Functional treatment and early weightbearing after an ankle fracture: a prospective study.

OBJECTIVE: Postoperative care for ankle fractures is generally 1 of 2 regimens: 1) functional treatment combined with early weightbearing (EWB), or 2) immobilization in a cast/orthosis for 6 weeks without weightbearing (6WC). The objective of this study was 2-fold: 1) to follow a prospective group treated with EWB as to long-term subjective and objective outcomes, and 2) to compare a subset of this group with a matched group of historic controls treated with 6WC. DESIGN: Prospective, clinical, cohort observation, and retrospective matched pair analysis. SETTING: University hospital, level 1 trauma center. PATIENTS: Forty-three patients (20 males; mean age, 49 +/- 14 years) with operated Weber B/C fractures underwent EWB. For comparison, 23 patients of this group were matched to a same number of historic controls with respect to age, gender, body mass index, and fracture type. INTERVENTION: Open reduction and internal fixation (ORIF) using a 1/3-tubular-fibula-plate for the fibula, and malleolar screws for the medial malleolus fracture (in cases with a bimalleolar ankle fracture) followed by EWB or 6WC. MAIN OUTCOME MEASUREMENTS: Olerud and Tegner scores at follow-up (at least 12 months after surgery), time to full weightbearing, return to work, pain intensity (numerical rating scale (NRS)), and hospital stay. Statistical comparisons were performed by using the Mann-Whitney U test or Fisher exact test (P < 0.05). RESULTS: Patients with EWB were full weightbearing at 7 +/- 3 weeks and returned to work at 8 +/- 5 weeks after surgery. At follow-up (mean, 20 +/- 11 months after surgery), all EWB patients showed good results in the Olerud score (90 +/- 13 points). Matched-pair analysis in 23 patients in each group revealed differences between EWB and 6WC groups for hospital stay (mean, 10.8 +/- 4.7 vs. 13.6 +/- 6 days; P = 0.12), time to full weightbearing (mean, 7.7 +/- 3.1 vs. 13.5 +/- 9.4 weeks; P = 0.01), and time until return to work (mean 9.2 +/- 5.5 vs. 10.8 +/- 7 weeks; P = 0.63). No differences concerning pain intensities were observed (EWB vs. 6WC: NRS = 1.9 vs. 1.7; P = 0.12). At follow-up, Olerud scores were generally considered good for both groups; however, mean values in EWB patients were slightly higher (87 +/- 14 vs. 79 +/- 19 points; P = 0.25). In both groups, the majority of patients reached their preinjury level of activity as demonstrated by Tegner scores. CONCLUSIONS: EWB patients tolerated earlier full weightbearing compared with 6WC patients, and there were no disadvantages with EWB compared with 6WC concerning hospital stay, pain intensities, time until return to work, and Olerud/Tegner Scores. Potential candidates for EWB are patients with a stable osteosynthesis of their fractured ankles as judged by the responsible surgeon, compliance, and high motivation.

Activities of Daily Living↗