Hypocapnia is a biological marker for orthostatic intolerance in some patients with chronic fatigue syndrome

CONTEXT: Patients with chronic fatigue syndrome and those with orthostatic intolerance share many symptoms, yet questions exist as to whether CFS patients have physiological evidence of orthostatic intolerance. OBJECTIVE: To determine if some CFS patients have increased rates of orthostatic hypotension, hypertension, tachycardia, or hypocapnia relative to age-matched controls. DESIGN: Assess blood pressure, heart rate, respiratory rate, end tidal CO2 and visual analog scales for orthostatic symptoms when supine and when standing for 8 minutes without moving legs. SETTING: Referral practice and research center. PARTICIPANTS: 60 women and 15 men with CFS and 36 women and 4 men serving as age matched controls with analyses confined to 62 patients and 35 controls showing either normal orthostatic testing or a physiological abnormal test. MAIN OUTCOME MEASURES: Orthostatic tachycardia; orthostatic hypotension; orthostatic hypertension; orthostatic hypocapnia or combinations thereof. RESULTS: CFS patients had higher rates of abnormal tests than controls (53% vs 20%, p < .002), but rates of orthostatic tachycardia, orthostatic hypotension, and orthostatic hypertension did not differ significantly between patients and controls (11.3% vs 5.7%, 6.5% vs 2.9%, 19.4% vs 11.4%, respectively). In contrast, rates of orthostatic hypocapnia were significantly higher in CFS than in controls (20.6% vs 2.9%, p < .02). This CFS group reported significantly more feelings of illness and shortness of breath than either controls or CFS patients with normal physiological tests. CONCLUSION: A substantial number of CFS patients have orthostatic intolerance in the form of orthostatic hypocapnia. This allows subgrouping of patients with CFS and thus reduces patient pool heterogeneity engendered by use of a clinical case definition

Blood pressure variability and closed-loop baroreflex assessment in adolescent chronic fatigue syndrome during supine rest and orthostatic stress

Hemodynamic abnormalities have been documented in the chronic fatigue syndrome (CFS), indicating functional disturbances of the autonomic nervous system responsible for cardiovascular regulation. The aim of this study was to explore blood pressure variability and closed-loop baroreflex function at rest and during mild orthostatic stress in adolescents with CFS. We included a consecutive sample of 14 adolescents 12–18 years old with CFS diagnosed according to a thorough and standardized set of investigations and 56 healthy control subjects of equal sex and age distribution. Heart rate and blood pressure were recorded continuously and non-invasively during supine rest and during lower body negative pressure (LBNP) of –20 mmHg to simulate mild orthostatic stress. Indices of blood pressure variability and baroreflex function (α-gain) were computed from monovariate and bivariate spectra in the low-frequency (LF) band (0.04–0.15 Hz) and the high–frequency (HF) band (0.15–0.50 Hz), using an autoregressive algorithm. Variability of systolic blood pressure in the HF range was lower among CFS patients as compared to controls both at rest and during LBNP. During LBNP, compared to controls, α-gain HF decreased more, and α-gain LF and the ratio of α-gain LF/α-gain HF increased more in CFS patients, all suggesting greater shift from parasympathetic to sympathetic baroreflex control. CFS in adolescents is characterized by reduced systolic blood pressure variability and a sympathetic predominance of baroreflex heart rate control during orthostatic stress. These findings may have implications for the pathophysiology of CFS in adolescents

Recent research on Gulf War illness and other health problems in veterans of the 1991 Gulf War: Effects of toxicant exposures during deployment

Veterans of Operation Desert Storm/Desert Shield - the 1991 Gulf War (GW) - are a unique population who returned from theater with multiple health complaints and disorders. Studies in the U.S. and elsewhere have consistently concluded that approximately 25-32% of this population suffers from a disorder characterized by symptoms that vary somewhat among individuals and include fatigue, headaches, cognitive dysfunction, musculoskeletal pain, and respiratory, gastrointestinal and dermatologic complaints. Gulf War illness (GWI) is the term used to describe this disorder. In addition, brain cancer occurs at increased rates in subgroups of GW veterans, as do neuropsychological and brain imaging abnormalities. Chemical exposures have become the focus of etiologic GWI research because nervous system symptoms are prominent and many neurotoxicants were present in theater, including organophosphates (OPs), carbamates, and other pesticides; sarin/cyclosarin nerve agents, and pyridostigmine bromide (PB) medications used as prophylaxis against chemical warfare attacks. Psychiatric etiologies have been ruled out. This paper reviews the recent literature on the health of 1991 GW veterans, focusing particularly on the central nervous system and on effects of toxicant exposures. In addition, it emphasizes research published since 2008, following on an exhaustive review that was published in that year that summarizes the prior literature (RACGWI, 2008). We conclude that exposure to pesticides and/or to PB are causally associated with GWI and the neurological dysfunction in GW veterans. Exposure to sarin and cyclosarin and to oil well fire emissions are also associated with neurologically based health effects, though their contribution to development of the disorder known as GWI is less clear. Gene-environment interactions are likely to have contributed to development of GWI in deployed veterans. The health consequences of chemical exposures in the GW and other conflicts have been called "toxic wounds" by veterans. This type of injury requires further study and concentrated treatment research efforts that may also benefit other occupational groups with similar exposure-related illnesses

Application of ecological momentary assessment in stress-related diseases

Many physical diseases have been reported to be associated with psychosocial factors. In these diseases, assessment relies mainly on subjective symptoms in natural settings. Therefore, it is important to assess symptoms and/or relationships between psychosocial factors and symptoms in natural settings. Symptoms are usually assessed by self-report when patients visit their doctors. However, self-report by recall has an intrinsic problem; "recall bias". Recently, ecological momentary assessment (EMA) has been proposed as a reliable method to assess and record events and subjective symptoms as well as physiological and behavioral variables in natural settings. Although EMA is a useful method to assess stress-related diseases, it has not been fully acknowledged, especially by clinicians. Therefore, the present brief review introduces the application and future direction of EMA for the assessment and intervention for stress-related diseases

Self-reports of pain and associated cardiovascular response dimensions during two types of the cold pressor test

Patterns of cardiovascular adjustments associated with self-reports of pain during the forehead and foot cold pressor (CP) tests were examined in 40 college men. Each subject participated in two CP sessions of the same type, one of which included ratings of pain. Blood pressure responses during the two tests were comparable in size. Cardiovascular response to foot stimulation consisted of a transient rise in cardiac output, followed by the increase in peripheral resistance, whereas during forehead stimulation, the increase in peripheral resistance was the primary mediator of the blood pressure increase throughout the test. Subjects in the foot CP group gave higher ratings of pain during stimulation than subjects in the forehead CP group. Ratings of pain made after an 8-min delay were identical for both groups. During both tests, increases in blood pressure were proportional to ratings of pain. During the forehead, but not the foot CP test, reporting pain was uniformly associated with increased systolic blood pressure responses through increased peripheral resistance. In contrast, the effect of the pain reporting procedure on diastolic blood pressure was inversely related to the level of reported pain.In the forehead, but not in the foot condition, subjects who responded to stimulation with increased cardiac output (30% of the sample), also gave higher pain ratings, without, however, demonstrating more than an average level of blood pressure increase. Among the remaining 70% of the subjects, in both CP groups, those who reported higher pain ratings also had higher blood pressure responses. This suggested that a positive relationship between blood pressure and pain was present among subjects who increased their blood pressure primarily by increasing their peripheral resistance, whereas the perception of pain was unrelated to blood pressure responses among subjects whose blood pressure increases were mediated in part by increases in cardiac output

Cardiovascular and perceptual effects of reporting pain during the foot and forehead cold pressor tests

In research involving the cold pressor test, a tacit presumption is often made that reporting pain during stimulation is not in itself reactive. This study examined whether, for the foot and forehead cold pressor tests, activities involved in reporting pain may affect (a) the evoked pattern of cardiovascular response, and (b) the magnitude of self-perceived pain. In 40 normotensive college men, increases in systolic blood pressure were greater during test sessions that included verbal ratings of pain, as compared to sessions in which pain was not reported. In contrast to its effect on physiological activation, reporting pain did not significantly alter the participant’s perception of the painfulness of the test, on recollection shortly after the test. We conclude, therefore, that reporting pain during the cold pressor test may impose significant additional demands on the cardiovascular system, but it docs not interfere significantly with the processing of nociceptive information

Baroreceptor reflex and integrative stress responses in chronic fatigue syndrome

Objective: Altered cardiovascular responses to mental and postural stressors have been reported in chronic fatigue syndrome (CFS). This study examined whether those findings may involve changes in baroreceptor reflex functioning. Methods: Chronotropic baroreceptor reflex (by sequential analysis) and cardiovascular stress responses were recorded during postural (5-minute of active standing) and cognitive (speech task) stress testing in patients with CFS grouped into cases with severe (N = 21) or less severe (N = 22) illness, and in 29 matched control subjects. Results: Patients with CFS had a greater decline in baroreceptor reflex sensitivity (BRS) during standing, although only those with severe CFS were significantly different from the controls. Systolic blood pressure declined during standing in the control group but was maintained in the CFS patients. In contrast, the patients with less severe CFS had blunted increases in blood pressure during the speech task, which could not, however, be explained by inadequate inhibition of the baroreceptor reflex, with all groups showing an appropriate reduction in BRS during the task. Conclusions: These results indicate that in CFS, deficiencies in orthostatic regulation, but not in centrally mediated stress responses, may involve the baroreceptor reflex. This study also suggests that classifying patients with CFS on illness severity may discriminate between patients with abnormalities in peripheral vs. central mechanisms of cardiovascular stress responses.65588989