Stress and heart rate variability in surgeons during a 24-hour shift.

OBJECTIVE: To determine the specific effects of working long hours in surgery and potential cardiac stress in the individual surgeon by measuring heart rate variability (HRV). DESIGN, SETTING, AND PARTICIPANTS: This prospective study measured HRV before, during, and after a 24-hour shift in a standardized resting period of 10 minutes. Measurements were repeated over 10 shifts for each participant. Eight surgeons from a high-volume inner-city surgery department took part in the study. MAIN OUTCOME MEASURES: Time and frequency domain parameters of HRV as parameters of cardiac stress and correlations with perceived stress and fatigue on a visual analog scale. RESULTS: Perceived fatigue increased over 24 hours (P < .001), whereas stress levels decreased slightly (P = .06). Time domain parameters of HRV increased from before the shift to after the shift (standard deviation of normal to normal intervals, square root of the mean normal to normal interval, and percentage of adjacent pairs of normal to normal intervals differing by more than 50 milliseconds: all P < .01), denoting more cardiac relaxation. Both the low- and high-frequency components increased (P = .04 and P < .001, respectively), showing a heightened activity of the autonomic nervous system. CONCLUSIONS: Measurements of HRV during a 24-hour surgical shift did not show an increase in cardiac stress concerning time domain parameters despite intense workloads for a median of 20 hours. Frequency components increased in parallel, though, suggesting alterations in sympathovagal balance. Perceived stress levels correlated with HRV, whereas fatigue did not. Further studies on occupational stress and its cardiac effects in surgeons are needed.

Urinary catecholamine responses in F-15 pilots: evaluation of the stress induced by long-distance flights.

Included in the Cooperative Cope Thunder exercises from Japan to Alaska is one of the longest distance flight missions carried out by Japan Air-Self Defense Force F-15 pilots. The magnitude of the flight stress of these pilots is considered to be quite high. The purpose of this study was to evaluate the flight stress induced by the long-distance flights. The subjects were eight pilots who participated on a volunteer basis. Samples of urine were collected approximately 30 minutes before (preflight) and 20 minutes after (postflight) the flights. The ratios (post-:preflight) of noradrenaline levels were 1.20 +/- 0.09 (Japan-Alaska) and 1.32 +/- 0.12 (Alaska-Japan), and those of adrenaline were 4.03 +/- 1.06 and 3.68 +/- 0.98. These results strongly suggest that psychological stress during the long-distance flights is increased in the fighter pilots.

Combat stress or hemorrhage? Evidence for a decision-assist algorithm for remote triage.

INTRODUCTION: In the setting of remote military triage, when physical access to the patient is not possible, traditional physiological measurements available to a combat medic may not differentiate between a wounded soldier and an active soldier. We tested the hypothesis that changes in high-frequency R-R interval spectral power (RRI HF) and pulse pressure (PP) would differ between progressive central hypovolemia (simulated hemorrhage) and exercise to evaluate their potential for remotely distinguishing active from bleeding soldiers. The RRI HF and PP were used because of their ability to track central hypovolemia. METHODS: There were 12 (8 female/4 male) healthy, normotensive, nonsmoking subjects (age 27 +/- 2 yr; height 169 +/- 3 cm; weight 68 +/- 5 kg) who were exposed to progressive lower body negative pressure (LBNP) and a supine cycle ergometer protocol. ECG and blood pressure were measured continuously. Exercise workloads were determined by matching the heart rate (HR) responses to each LBNP level. Data were analyzed in time and frequency domains. RESULTS: HR increased from 67 +/- 3 bpm at rest to 101 +/- 4 bpm by -60 mmHg LBNP and was matched within 5% during exercise. By the final stage, RRI HF decreased by a similar magnitude during both LBNP (-78 +/- 7%) and exercise (-85 +/- 6%). PP decreased by 30 +/- 4% with LBNP compared with an increase of 20 +/- 6% during exercise. CONCLUSION: Monitoring PP in combination with RRI HF would distinguish a bleeding from an active soldier. Technologies that incorporate telemetry to track these derived vital signs would provide a combat medic with remote decision support to assess soldier status on the battlefield.

Measurement of surgical stress in anaesthetized children.

BACKGROUND: The surgical stress index (SSI), derived from a combination of heart rate (HR) and photoplethysmographic amplitude (PPGA) time series, is a novel method for continuous monitoring of intraoperative stress and has been validated in adults. The applicability of SSI and its constituents to monitoring children has not been previously evaluated. METHODS: In this controlled trial, 22 anaesthetized patients, aged 4-17 yr, undergoing strabismus surgery were randomized into two groups, Group LL and Group BSS. Patients in Group LL received topical conjunctival anaesthesia with a 1:1 mixture of lidocaine 2% and levobupivacaine 0.75%, and patients in Group BSS received balanced salt solution. RESULTS: Endotracheal intubation (n=22) increased median (range) SSI from 39.2 (22.6-55.6) to 53.6 (35.8-63.3) (P<0.001), decreased PPGA from 5.62 (2.79-9.69) to 5.27 (2.59-7.54)% (P=0.001), and increased the difference of response entropy (RE) and state entropy (SE) of frontal biopotentials (RE-SE) from 3.1 (0.06-9.1) to 5.7 (0.6-9.4) (P=0.01). Conventional haemodynamic variables also increased, median (range) HR from 72.9 (56.7-113.8) to 84.2 (60.4-124.8) beats min(-1) (P<0.001), and systolic non-invasive arterial pressure (S-NIBP) from 87 (78-143) to 103 (79-125) (P=0.007). When 3 min baseline before surgery was compared with 12 min of surgery, median (range) SSI increased from 43.3 (31.2-58.0) to 49.9 (39.3-57.2) (P=0.042) vs from 46.6 (26.8-57.8) to 52.1 (31.7-60.1) (P=0.024) and PPGA decreased from 6.60 (3.10-8.24) to 5.80 (3.03-7.65)% (P<0.001) vs from 5.51 (3.25-9.84) to 5.06 (3.08-8.99)% (P=0.042), in Groups LL and BSS, respectively, but SSI or other indicators did not differ significantly between the groups. CONCLUSIONS: SSI, PPGA, HR, NIBP, RE, and RE-SE detect autonomic responses to nociceptive stimuli in anaesthetized children undergoing strabismus surgery.

E-PASS for predicting postoperative risk with hip fracture: a multicenter study.

UNLABELLED: This multicenter study of 813 consecutive patients with hip fracture was performed to estimate the effectiveness and reproducibility of the Estimation of Physiologic Ability and Surgical Stress (E-PASS) scoring system to assess postoperative risk in patients with hip fracture. E-PASS is comprised of a preoperative risk score, a surgical stress score, and a comprehensive risk score based on the preoperative risk score and surgical stress score. Postoperative complications developed in 163 patients (20.0%); 13 (1.6%) died. Hospital postoperative morbidity and mortality rates increased linearly with the preoperative risk score and comprehensive risk score; the correlation was significant. The severity of postoperative complications and the incidence of higher grades of complications increased significantly with rising preoperative risk score and comprehensive risk score. Each E-PASS score also was related significantly with the length of postoperative hospitalization and costs. These results suggest E-PASS is useful for predicting postoperative risk, estimating costs, and for comparing the outcome in patients having surgical treatment of hip fractures. LEVEL OF EVIDENCE: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Stress and burnout in anaesthesia.

PURPOSE OF REVIEW: Recently, many researchers have been studying stress and burnout in anaesthesia. Some researchers have examined the effects of stress in the workplace. Others have identified some job characteristics that have an impact on anaesthetist's well-being. Yet, few studies use the same measure of stress and/or define the concept of stress in the same way, making comparison and aggregation of results difficult, and therefore minimizing the general impact of these research findings. RECENT FINDINGS: The following review focuses on the increasing recent research on stress and burnout in anaesthesia regarding the existing stress models and shows where the progress has been made, and where difference of opinion and divergence of approach remain. SUMMARY: From the referred studies, the review challenges the more practical problems of prevention of stress and burnout and provides some avenues for future investigations.

Parental response to children's pain: the moderating impact of children's emotional distress on symptoms and disability.

Parental responses play a central role in the development and maintenance of children's pain behavior. Previous studies examining the impact of parental responses on children's pain have focused mainly on protective or solicitous responses. This study examined the impact of parental responses, including protectiveness, minimization of pain, and encouraging and monitoring responses, on children's functional disability and somatic symptoms. Participants included 327 patients with chronic pain, ages 8-17, who completed measures of pain, disability, somatic symptoms, depression, and anxiety. Patients' parents completed a measure assessing parental responses to their children's pain. Results show that for children with higher levels of emotional distress, maladaptive parental responses to pain (e.g., criticism, discounting of pain, increased attention to pain, and granting of special privileges) were associated with increased disability and somatic symptoms. Results of this study demonstrate the important ways in which parents can influence how their children cope with and manage chronic pain. Children whose parents are overly protective or critical of their pain may experience more impairment or somatic symptoms, particularly those children who are already at risk for difficulties due to higher levels of emotional distress.

Correlation between immune and neuronal parameters and stress perception in allergic asthmatics.

BACKGROUND: Asthma is a chronic disease defined by airway inflammation, increased airway hyperresponsiveness and episodes of airway obstruction. Although there are abundant clinical and experimental data showing that stress may worsen asthma, the mechanisms linking stress to asthma are not well understood. By inducing a pro-inflammatory cytokine milieu, stress might enhance airway inflammation in bronchial asthma. We therefore investigated the correlation of stress perception and the cytokine profile of circulating lymphocytes in humans. METHODS: Allergic asthmatic patients and healthy controls were evaluated for perceived level of stress, demographic and lung function data. Whole blood cells were obtained and stimulated by mitogen to assess intracellular IL-4, IFN-gamma and TNF-alpha by flow cytometry. Neurotrophins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were measured in serum. RESULTS: Asthmatic patients showed significantly higher percentages of TNF-alpha-producing T cells than healthy controls. Only in asthmatic patients was stress perception correlated with percentages of TNF-alpha-producing T cells and serum BDNF levels, while forced expiratory volume in 1 s (% predicted) was negatively correlated to BDNF. CONCLUSION: The results of our study support the hypothesis that stress deteriorates bronchial asthma by inducing a pro-inflammatory cytokine profile in allergic asthmatics. Stress management might provide a supplement therapy of allergic asthma.

Phenomenology of mixed states: a principal component analysis study.

OBJECTIVES: To contribute to the definition of external and internal limits of mixed states and study the place of dysphoric symptoms in the psychopathology of mixed states. METHODS: One hundred and sixty-five inpatients with major mood episodes were diagnosed as presenting with either pure depression, mixed depression (depression plus at least three manic symptoms), full mixed state (full depression and full mania), mixed mania (mania plus at least three depressive symptoms) or pure mania, using an adapted version of the Mini International Neuropsychiatric Interview (DSM-IV version). They were evaluated using a 33-item inventory of depressive, manic and mixed affective signs and symptoms. RESULTS: Principal component analysis without rotation yielded three components that together explained 43.6% of the variance. The first component (24.3% of the variance) contrasted typical depressive symptoms with typical euphoric, manic symptoms. The second component, labeled 'dysphoria', (13.8%) had strong positive loadings for irritability, distressing sensitivity to light and noise, impulsivity and inner tension. The third component (5.5%) included symptoms of insomnia. Median scores for the first component significantly decreased from the pure depression group to the pure mania group. For the dysphoria component, scores were highest among patients with full mixed states and decreased towards both patients with pure depression and those with pure mania. CONCLUSIONS: Principal component analysis revealed that dysphoria represents an important dimension of mixed states.

Assessment of slow-breathing relaxation technique in acute stressful tasks using a multipurpose non-invasive beat-by-beat cardiovascular monitoring system.

Recently, several studies revealed that daily slow-breathing exercise lowered blood pressure and increased baroreflex sensitivity. With this interesting finding, we have been contemplating to design a compact breath-controllable device for relaxation to stress reaction during daily living for home as well as ambulatory use, as a final goal, towards reduction of cognitive hemodynamic disorders, hypertension, and acute stress-induced hemodynamic disorders. The present study thereby describes, as a first step, to design a prototype system combining a compact multipurpose non-invasive beat-by-beat cardiovascular monitor developed previously with a wrist-type vibrator to make a respiration rhythm, and to assess an effect of slow-breathing relaxation on the cardiovascular hemodynamics in response to acute stressful conditions. The cardiovascular hemodynamic monitor can measure beat-by-beat systolic (SBP), mean (MBP) and diastolic (DBP) pressure in a finger based on the volume-compensation method, cardiac output (CO) by the electrical admittance method and the other hemodynamic-related parameters (e.g., total peripheral resistance (TPR=MBP/CO), heart rate (HR), respiratory rate, pulse wave velocity, etc.). The wrist-type vibrator can give various breathing rhythms quietly to a subject using a small vibration motor. The stressful tasks loaded to healthy volunteers (3 males, 23-34 yrs.) in the experiments were cold pressor and arithmetic ones as a representative of daily passive and active coping tasks, respectively, under conditions with (respiratory rate of 6 1/min) and without breath control.. The results showed that the slow-breathing technique could have a significant effect on improvement of the hemodynamic changes following the acute stressful tasks, especially in the passive coping task.

The relationship between stress and hair cortisol in healthy pregnant women.

PURPOSE: Stress has been shown to cause a large range of adverse fetal effects. This pilot study is the first attempt to examine cortisol level in the hair of pregnant women and assess its potential as a biomarker of gestational stress. PATIENTS AND METHODS: Twenty-five healthy pregnant women, in whom hair cortisol levels and the Perceived Stress Scale (PSS) were measured and correlated. RESULTS: Maternal hair cortisol levels, ranging between 0.06 and 0.23 nmol/g of hair correlated positively and significantly with measures of perceived stress (ranging between 2-22); (Rs=0.47) (P < 0.05). CONCLUSIONS: Our findings corroborate recent primate studies with induced stress, and suggest that hair cortisol is a potential biomarker of chronic stress in pregnancy. This new long term biological marker may have important implications in research and clinical practice.

Extremity movements help occupational therapists identify stress responses in preterm infants in the neonatal intensive care unit: a systematic review.

BACKGROUND: Accurate assessment and treatment of pain and stress in preterm infants in neonatal intensive care units (NICU) is vital because pain and stress responses have been linked to long-term alterations in development in this population. PURPOSE: To review the evidence of specific extremity movements in preterm infants as observed during stressful procedures. METHODS: Five on-line databases were searched for relevant studies. For each study, levels of evidence were determined and effect size estimates were calculated. Each study was also evaluated for specific factors that presented potential threats to its validity. RESULTS: Eighteen studies were identified and seven comprised the review. The combined sample included 359 preterm infants. Six specific movements were associated with painful and intrusive procedures. CLINICAL IMPLICATIONS: A set of specific extremity movements, when combined with other reliable biobehavioural measures of pain and stress, can form the basis for future research and development of a clinical stress scale for preterm infants.

Methods to quantify intermittent exercises.

The purpose of this study was to quantify intermittent training sessions using different types of exercise. Strength, sprint, and endurance sessions were performed until exhaustion. These sessions were quantified by the product of duration and heart rate (HR) (i.e., training impulse (TRIMP) and HR-zone methods), by the product of duration and rate of perceived exertion (RPE-based method), and a new method (work endurance recovery (WER)). The WER method aims to determine the level of exercise-induced physiological stress using the ratio of cumulated work - endurance limit, which is associated with the naparian logarithm of the ratio of work-recovery. Each session's effects were assessed using blood lactate, delayed onset muscle soreness (DOMS), RPE, and HR. Because sessions were performed until exhaustion, it was assumed that each session would have a similar training load (TL) and there would be low interindividual variability. Each method was used to compare each of the TL quantifications. The endurance session induced the higher HR response (p < 0.001), the sprint session the higher blood lactate increase (p < 0.001), and the strength session the higher DOMS when compared with sprint (p = 0.007). TLs were similar after WER calculations, whereas the HR- and RPE-based methods showed differences between endurance and sprint (p < 0.001), and between endurance and strength TL (p < 0.001 and p < 0.01, respectively). The TLs from WER were correlated to those of the HR-based methods of endurance exercise, for which HR was known to accurately reflect the exercise-induced physiological stress (r = 0.63 and r = 0.64, p < 0.05). In addition, the TL from WER presented low interindividual variability, yet a marked variability was observed in the TLs of HR- and RPE-based methods. As opposed to the latter two methods, WER can quantify varied intermittent exercises and makes it possible to compare the athletes' TL. Furthermore, WER can also assist in comparing athlete responses to training programs.

Biology and therapy of fibromyalgia. Stress, the stress response system, and fibromyalgia.

Stress is a state of disharmony, or threatened homeostasis. A stressor could have a psychological origin or a biological origin. Societies have become more intricate with industrialization, and modern individuals try to adapt to the new defiance by forcing their stress response system. The main component of the stress response network is the autonomic nervous system. The present article reviews current knowledge on autonomic dysfunction in fibromyalgia. Sympathetic hyperactivity has been consistently described by diverse groups of investigators. Fibromyalgia is proposed to be a sympathetically maintained neuropathic pain syndrome, and genomic data support this contention. Autonomic dysfunction may also explain other fibromyalgia features not related to pain.

Neurophysiologic methods to measure stress during survival, evasion, resistance, and escape training.

Training in Survival, Evasion, Resistance, and Escape (SERE) is required for U.S. military members at high risk of capture. This physically and psychologically demanding course is considered an analog to the stress imposed by war, captivity, and related events, thus offering a unique and unprecedented medium in which to systematically examine human stress and performance during a realistically intense operational context. Operational stress is multifaceted, manifesting cerebral, neuroendocrine, cardiac, and cognitive characteristics, and necessitating an integration of multiple methods of measurement to appropriately characterize its complexity. Herein we describe some of our present research methods and discuss their applicability to real-time monitoring and predicting of key aspects of human performance. A systems approach is taken, whereby some of the "key players" implicated in the stress response (e.g., cerebral, neuroendocrine, cardiac) are briefly discussed, to which we link corresponding investigative techniques (fMRI, acoustic startle eye-blink reflex, heart rate variability, and neuroendocrine sampling). Background and previous research with each investigative technique and its relationship to the SERE context is briefly reviewed. Ultimately, we discuss the operational applicability of each measure, that is, how each may be integrated with technologies that allow computational systems to adapt to the performer during operational stress.

Potential paradigm for assessments of biomedical technologies in the operational environment.

The U.S. Army Medical Research and Materiel Command Cognitive Performance, Judgment, Decision-making Research Program (CPJDRP) was initiated in part to prevent/mitigate performance shortfalls associated with cognitive-psychological combat stressors such as workload, fatigue, sleep, and nutritional aspects. An Operational Processes and Cognitive Mapping Focus Team (OPCMFT) was established for the purposes of integrating laboratory-based research into operational environments, embedding metrics into appropriate operational platforms, and providing an operational perspective to research that may veer off pragmatic and utilitarian courses. The OPCMFT's goal as originally formulated in 2004 was to determine operational requirements and test environments for evaluating cognitive performance metrics and models, pharmacological countermeasures, and neurocognitive monitors for the purpose of sustaining warfighter cognitive performance in operational environments (2). This preface first reviews the OPCMFT's major deliverables as developed from the CPJDRP workshop in 2005 (6). Next, a gap/needs analysis of cognitive research products and test and evaluation platforms is presented. Lastly, a summary of each of the three articles-one on the role and mitigation of stress, a second on the development of intellectual ability norms and statistical methods to interpolate an individual's post-morbid capabilities, and a third on a specific measure to assess physiological reactions to cognitive stressors--illustrates how each contributes to the effort to help improve warfighter cognitive performance. The preface authors emphasize the need for an integrated research program focused on the Battle Laboratory (1) with a solid infrastructure and an integration of the operational end-user, human factors, medical practitioners, and research and development expertise.

Cognitive activation theory of stress, sensitization, and common health complaints.

According to the cognitive activation theory of stress (CATS), a formal system of systematic definitions, the term "stress" is used for stress stimuli, the stress experience, the nonspecific, general stress response, and the experience of the stress response. The stress response is normal, healthy, and necessary alarm. If sustained there may be a risk of illness and disease. The level and duration of the alarm depend on the expectancy of the outcome of stimuli and the specific responses available for coping. The most common health complaints are subjective health complaints like muscle pain, tiredness and mood changes. These are normal aches of short duration and low intensity for most people. For some the pains and complaints are substantial and longlasting with serious implications for functioning. There are no sharp or obvious limits in the distribution of health complaints, separating "normal" and endurable pain and complaints, and intolerable complaints that need professional help. These conditions are most often unspecific, and are the most common reason for encounters with health professionals, and the most frequent reason for sick leave and disability. There is a striking comorbidity for all these conditions. This may be explained by psychobiological sensitization within neural loops, maintained by sustained activation, which has been suggested as a mechanism for these conditions.

IACUC issues associated with amphibian research.

Numerous species of amphibians are frequently utilized as animal models in biomedical research. Despite their relatively common occurrence as laboratory animals, the regulatory guidelines that institutional animal care and use committees (IACUCs) must employ provide little in the way of written standards for ectothermic animals. Yet, as vertebrates, laboratory amphibians are covered by the National Research Council Guide for the Care and Use of Laboratory Animals and the Public Health Service (PHS) Policy for federally funded research. This article focuses on three issues that are relevant to IACUC oversight of the use of amphibians in research: (1) recommended educational requirements of investigators and animal care staff engaged in research with amphibians, (2) zoonoses and other issues of occupational health importance, and (3) indicators of stress and disease. Addressing these issues should enable investigators, IACUCs, and animal care staff to meet the regulatory expectations of the PHS and accrediting bodies such as the Association for Assessment and Accreditation of Laboratory Animal Care International.