Hemodynamic instability in chronic fatigue syndrome: indices and diagnostic significance.

OBJECTIVES: To evaluate the cardiovascular response to postural challenge in patients with chronic fatigue syndrome (CFS) and to determine whether the degree of instability of the cardiovascular response may aid in diagnosing CFS. METHODS: Patients with CFS (n = 25) and their age- and gender-matched healthy controls (n = 37), patients with fibromyalgia (n = 30), generalized anxiety disorder (n = 15), and essential hypertension (n = 20) were evaluated with the aid of a standardized tilt test. The blood pressure (BP) and heart rate (HR) were recorded during 10 minutes of recumbence and 30 minutes of head-up tilt. We designated BP changes as the differences between successive BP values and the last recumbent BP. The average and standard deviation (SD) were calculated. Time curves of BP differences were loaded into a computerized image analyzer, and their outline ratios and fractal dimensions were measured. HR changes were determined similarly. The average and SD of the parameters were calculated, and intergroup comparisons were performed. RESULTS: On multivariate analysis, the independent predictors of CFS patients versus healthy controls were the fractal dimension of absolute values of the systolic BP changes (SYST-FD.abs), the standard deviation of the current values of the systolic BP changes (SYST-SD.cur), and the standard deviation of the current values of the heart rate changes (HR-SD.cur). The following equation was deduced to calculate the hemodynamic instability score (HIS) in the individual patient: HIS = 64.3303 + (SYST-FD.abs x -68.0135) + (SYST-SD.cur x 111.3726) + (HR-SD.cur x 60.4164). The best cutoff differentiating CFS from the healthy controls was -0.98. HIS values >-0.98 were associated with CFS (sensitivity 97%, specificity 97%). The HIS differed significantly between CFS and other groups (P <.0001) except for generalized anxiety disorder. Group averages (SD) of HIS were CFS = +3.72 (5.02), healthy = -4.62 (2.26), fibromyalgia = -3.27 (2.63), hypertension = -5.53 (2.24), and generalized anxiety disorder = +1.08 (5.2). CONCLUSION: The HIS adds objective criteria confirming the diagnosis of CFS.

The Haemodynamic Instability Score (HIS) for assessment of cardiovascular reactivity in hypertensive and normotensive patients.

The normal response to postural challenge is characterised by maintenance of relatively stable blood pressure (BP) and heart rate (HR) after 30 sec to 30 min of head-up tilt. The objective of the present study was to determine the degree of instability of cardiovascular responses to postural challenge in normotensive and hypertensive subjects. In the initial phase of the study, two groups of age and sex-matched subjects were assessed: essential hypertension (n = 20) and healthy (n = 37). The BP and HR were recorded at 5-min intervals during the course of the 10-min supine-30-min head-up tilt test (HUTT). We categorised 'BP-change' as the difference between individual BP measurements during HUTT and the last recumbent BP value, divided by latter value. The average and standard deviation (SD) of the recorded BP changes were calculated, and BP changes were plotted along a time curve. A computerised image analyser then calculated the outline ratio (OR) and fractal dimension (FD) values for each of the curves. An identical process evaluated measurements for HR-changes. BP- and HR-changes were then converted into absolute numbers, and the average, SD, OR, and FD were calculated. A multivariate analysis was conducted, evaluating independent predictors of hypertension. Finally, an equation for the calculation of 'haemodynamic instability score' (HIS) was deduced and a cut-off between HIS of hypertensive and normotensive subjects was established. Independent predictors of the cardiovascular response to postural challenge of hypertensives (Group I) vs healthy (Group II) were: a.DIAST-FD, a.HR-AVG, a.HR-SD, a.HR-FD, DIAS-SD and HR-SD and HR-SD. Based on these five predictors, a linear discriminant score was computed and called the Haemodynamic Instability Score (HIS): HIS = 59.4 + (-16.6*a.DIAST-FD) + (-29.0*a.HR-AVG) + (-82.4*a.HR-SD) + (-30.1*a.HR-FD) + (-57.9*DIAS-SD) + (73.4*HR-SD) The HIS values in Group I (hypertensives) were: avg = 3.348, SD = 2.863, and 95% CI for mean = 2.008, 4.688. The HIS values in Group II (healthy) were: avg = -3.394, SD = 2.435, 95% CI for mean = -4.206, -2.582. Values of the HIS > -2.09 were generally observed in hypertensives (sensitivity 95%) and values < or = -2.09 were usually seen in the healthy (specificity 81.1%). The HIS was cross-validated in an additional group of hypertensive patients (n = 73). In the latter group, the HIS values were: avg = -0.456, SD = 4.403, 95% CI for mean = -1.506, 0.593 and 71.4% sensitivity at the proposed cut-off point. In conclusion, the HIS confers numerical expression to the degree of lability of BP and HR during postural challenge. Based on this score, a distinction between the cardiovascular reactivity of hypertensives vs normotensives is drawn. Possible applications of HIS are discussed.

Outcome of direct percutaneous endoscopic jejunostomy tube placement for nutritional support in critically ill, mechanically ventilated patients.

PURPOSE: Gastrointestinal function is adversely affected in critically ill mechanically ventilated patients. The most common abnormality is delayed gastric emptying. Among the options for postpyloric feeds, direct percutaneous endoscopic jejunostomy (PEJ) provides a permanent, reliable, and direct access to the small bowel and can be used for full enteral feedings, thus eliminating the need for parenteral nutrition. PATIENTS AND METHODS: All patients who underwent direct PEJ tube placement while mechanically ventilated in the intensive care unit (ICU) were evaluated. For each patient the following factors were identified: age, indication for ICU admission and PEJ placement, nutritional support before and after PEJ placement, calories received, complications, and outcome. RESULTS: Seventeen patients underwent the procedure. All had successful placement of direct PEJ tube. There was a single complication. Within 24 hours of PEJ placement, 16 of 17 patients tolerated jejunal feedings. All patients progressed to their established nutritional goals. There were no cases of aspiration of enteral feedings. In the 16 patients, total parenteral nutrition (TPN) was not required once PEJ tubes were placed. Thirteen patients were discharged home or to a rehabilitation facility with jejunal feedings. CONCLUSIONS: Direct PEJ placement is a safe and reliable device that can be successfully placed in critically ill, mechanically ventilated patients. With this procedure, all patients can meet their nutritional requirements and eliminate the need for TPN.

Flow triggering added to pressure support ventilation improves comfort and reduces work of breathing in mechanically ventilated patients.

PURPOSE: The purpose of this study was to measure the effect of flow triggering (FT), added to pressure support ventilation (PSV), during spontaneous breathing in intubated patients. MATERIALS AND METHODS: A prospective observational study was conducted at a Comprehensive Cancer Center, University Hospital. Fourteen consecutive critically ill, mechanically ventilated patients on PSV with positive end-expiratory pressure were studied. Flow triggering was added to PSV in spontaneously breathing ventilated patients. RESULTS: Respiratory rate (f), minute ventilation (Vepsilon), patient work of breathing (WOBp), respiratory drive (P0.1), rapid shallow breathing index (f/Vt), tidal volume (Vt) and a visual analog scale of breathing effort and comfort all improved. There was a large decrease in WOBp and P0.1 when flow triggering was added to PSV (P<.001). There was a moderate decrease in f/V1 during the same procedure (P<.01). Twelve patients felt subjectively better with the intervention. CONCLUSIONS: Flow triggering offers an excellent complement to PSV because it improves patient comfort and reduces the magnitude of the inspiratory effort as well as the delay time between inspiratory muscle contraction and gas flow. It augments gas exchange at no metabolic cost to the patient while reducing the work of breathing.

Ontogeny, compartmentation, and turnover of spectrin isoforms in rat central neurons.

A variant of a principal structural protein of erythrocytes, spectrin, is a major neuronal protein. Here we have examined the subcellular and regional distributions, subunit composition, ontogeny, and metabolism of spectrin in rat CNS. While all subcellular fractions, except the mitochondrial, expressed the previously characterized brain form of spectrin (fodrin, or alpha gamma-spectrin), limited brain regions contained, in cytoplasm, a second isoform immunologically related to erythrocyte alpha beta-spectrin. Both alpha gamma- and alpha beta-spectrin are primarily neuronal, as evidenced by immunocytochemistry. The spectrins are distributed between 2 distinct subneuronal compartments: a membrane-associated domain containing alpha gamma-spectrin in relatively constant amounts across brain regions, and a cytoplasmic domain containing both the alpha gamma and alpha beta isoforms in widely varying amounts across brain regions. Although forebrain has considerable alpha beta-spectrin, the diencephalon, mesencephalon, and brain stem are devoid of this isoform. Further evidence for spectrin compartmentation comes from its ontogeny. Membrane-associated alpha gamma-spectrin is present at birth at its adult levels, but cytoplasmic alpha beta-spectrin is expressed only following the second postnatal week. Similarly, the 4-fold difference in cytoplasmic alpha gamma-spectrin content across brain regions develops during the third postnatal week. In this compartment, both spectrin forms may be metabolized in vivo, at least in part, by calcium-activated proteolysis. The presence in mammalian neurons of 2 spectrin isoforms and their compartmentation into distinct domains suggests multiple functions for neuronal spectrin, one of which may be in the stabilization or maturation of forebrain neurons.

Cardiovascular response to upright tilt in fibromyalgia differs from that in chronic fatigue syndrome.

OBJECTIVE: To compare the cardiovascular response during postural challenge of patients with fibromyalgia (FM) to those with chronic fatigue syndrome (CFS). METHODS: Age and sex matched patients were studied, 38 with FM, 30 with CFS, and 37 healthy subjects. Blood pressure (BP) and heart rate (HR) were recorded during 10 min of recumbence and 30 min of head-up tilt. Differences between successive BP values and the last recumbent BP, their average, and standard deviation (SD) were calculated. Time curves of BP differences were analyzed by computer and their outline ratios (OR) and fractal dimensions (FD) were measured. HR differences were determined similarly. Based on the latter measurements, each subject's discriminant score (DS) was computed. RESULTS: For patients and controls average DS values were: FM: -3.68 (SD 2.7), CFS: 3.72 (SD 5.02), and healthy controls: -4.62 (SD 2.24). DS values differed significantly between FM and CFS (p < 0.0001). Subgroups of FM patients with and without fatigue had comparable DS values. CONCLUSION: The DS confers numerical expression to the cardiovascular response during postural challenge. DS values in FM were significantly different from DS in CFS, suggesting that homeostatic responses in FM and CFS are dissimilar. This observation challenges the hypothesis that FM and CFS share a common derangement of the stress-response system.