The relation between cognitive-behavioural responses to symptoms in patients with long term medical conditions and the outcome of cognitive behavioural therapy for fatigue - A secondary analysis of four RCTs.

BACKGROUND: Cognitive behavioural therapy (CBT) is effective in reducing fatigue across long-term conditions (LTCs). This study evaluated whether cognitive and behavioural responses to symptoms: 1) differ between LTCs and 2) moderate and/or mediate the effect of CBT on fatigue. METHOD: Data were used from four Randomized Controlled Trials testing the efficacy of CBT for fatigue in Chronic Fatigue Syndrome/ME (N = 240), Multiple Sclerosis (N = 90), Type 1 Diabetes Mellitus (N = 120) and Q-fever fatigue syndrome (N = 155). Fatigue severity, assessed with the Checklist Individual Strength, was the primary outcome. Differences in fatigue perpetuating factors, assessed with the Cognitive Behavioural Responses to Symptoms Questionnaire (CBRQ), between diagnostic groups were tested using ANCOVAs. Linear regression and mediation analyses were used to investigate moderation and mediation by CBRQ scores of the treatment effect. RESULTS: There were small to moderate differences in CBRQ scores between LTCs. Patients with higher scores on the subscales damage beliefs and avoidance/resting behaviour at baseline showed less improvement following CBT, irrespective of diagnosis. Reduction in fear avoidance, catastrophising and avoidance/resting behaviour mediated the positive effect of CBT on fatigue across diagnostic groups. DISCUSSION: The same cognitive-behavioural responses to fatigue moderate and mediate treatment outcome across conditions, supporting a transdiagnostic approach to fatigue.

Drug use is associated with lower plasma magnesium levels in geriatric outpatients; possible clinical relevance.

BACKGROUND: Hypomagnesemia has been associated with diabetes, cardiovascular disease, and other disorders. Drug use has been suggested as one of the risk factors for low magnesium (Mg) levels. In the elderly population, prone to polypharmacy and inadequate Mg intake, hypomagnesemia might be relevant. Therefore, we aimed to investigate associations between drug use and plasma Mg. METHODS: Cross-sectional data of 343 Dutch geriatric outpatients were analysed by Cox and linear regression, while adjusting for covariates. Drug groups were coded according to the Anatomical Therapeutic Chemical classification system; use was compared to non-use. Hypomagnesemia was defined as plasma Mg < 0.75 mmol/l and <0.70 mmol/l. RESULTS: Prevalence of hypomagnesemia was 22.2% (Mg < 0.75 mmol/l) or 12.2% (Mg < 0.70 mmol/l); 67.6% of the patients used ≥5 medications (polypharmacy). The number of different drugs used was inversely linearly associated with Mg level (beta -0.01; p < 0.01). Fully adjusted Cox regression showed significant associations of polypharmacy with hypomagnesemia (Mg < 0.75 mmol/l) (prevalence ratio (PR) 1.81; 95%CI 1.08-3.14), proton pump inhibitors (PR 1.80; 95%CI 1.20-2.72), and metformin (PR 2.34; 95%CI 1.56-3.50). Moreover, stratified analyses pointed towards associations with calcium supplements (PR 2.26; 95%CI 1.20-4.26), insulins (PR 3.88; 95%CI 2.19-6.86), vitamin K antagonists (PR 2.01; 95%CI 1.05-3.85), statins (PR 2.44; 95%CI 1.31-4.56), and bisphosphonates (PR 2.97; 95%CI 1.65-5.36) in patients <80 years; selective beta blockers (PR 2.01; 95%CI 1.19-3.40) if BMI <27.0 kg/m2; and adrenergic inhalants in male users (PR 3.62; 95%CI 1.73-7.56). Linear regression supported these associations. CONCLUSION: As polypharmacy and several medications are associated with hypomagnesemia, Mg merits more attention, particularly in diabetes, cardiovascular disease, and in side-effects of proton pump inhibitors and calcium supplements.

Efficacy of web-based cognitive-behavioural therapy for chronic fatigue syndrome: randomised controlled trial.

BACKGROUND: Face-to-face cognitive-behavioural therapy (CBT) leads to a reduction of fatigue in chronic fatigue syndrome (CFS). Aims To test the efficacy of internet-based CBT (iCBT) for adults with CFS. METHOD: A total of 240 patients with CFS were randomised to either iCBT with protocol-driven therapist feedback or with therapist feedback on demand, or a waiting list. Primary outcome was fatigue severity assessed with the Checklist Individual Strength (Netherlands Trial Register: NTR4013). RESULTS: Compared with a waiting list, intention-to-treat (ITT) analysis showed a significant reduction of fatigue for both iCBT conditions (protocol-driven feedback: B = -8.3, 97.5% CI -12.7 to -3.9, P < 0.0001; feedback on demand: B = -7.2, 97.5% CI -11.3 to -3.1, P < 0.0001). No significant differences were found between both iCBT conditions on all outcome measures (P = 0.3-0.9). An exploratory analysis revealed that feedback-on-demand iCBT required less therapist time (mean 4 h 37 min) than iCBT with protocol-driven feedback (mean 6 h 9 min, P < 0.001) and also less than face-to-face CBT as reported in the literature. CONCLUSIONS: Both iCBT conditions are efficacious and time efficient. Declaration of interest None.

Maintenance interventions for overweight or obesity in children: a systematic review and meta-analysis.

Childhood obesity is associated with significant health consequences. Although several intervention programmes for children result in weight loss or stabilization in the short-term, preventing relapse after treatment remains an important challenge. This systematic review summarizes the evidence about maintenance interventions after treatment in childhood obesity. Studies were identified by searching PubMed, Embase, Cochrane Library, Scopus, Web of Science, PsycINFO, CINAHL and SocINDEX. The primary outcome measure for this review was body mass index standard deviation score (BMI-Z-score). Data were pooled using quality effect models. Eleven studies (1,532 participants, age 2-18 years) were included, covering a wide range of maintenance approaches. Included studies varied widely in methodological quality. Pooled analysis showed that the BMI-Z-score of maintenance intervention participants remained stable, whereas control participants experienced a slight increase. No differences were observed regarding intensity and duration of therapy. A slight preference for 'face-to-face' versus 'on distance' interventions was shown. In summary, this review shows that, although there is limited quality data to recommend one maintenance intervention over another, continued treatment does have a stabilizing effect on BMI-Z-score. Considering the magnitude of the problem of childhood obesity, this is an important finding that highlights the need for further research on weight loss maintenance.

Development of a Dutch intervention for obese young children.

The objective of this article is to provide insight in the five-step development process of the best evidence, best practice intervention for obese young children 'AanTafel!'. A set of requirements for intervention development was developed to guide the data inquiry: the use of theory, influencing factors, tailoring, multi-disciplinarity, duration/frequency and evaluation and monitoring. Step I retrieved evidence from clinical guidelines, followed by a systematic review with meta-analysis (Step II) and an extended literature review (Step III). Evidence was consistent with regard to parent-focus, targeting family level, including diet, physical activity and behaviour change techniques and tailoring to age. However, no evidence or inconsistent evidence emerged from the theory-basis, group-versus-individual sessions, face-to-face contact versus Internet-mediated contact, which disciplines to involve and how to involve them, as well as intervention duration and intensity. Hence, practice-based insights from parental interviews (Step IV) and involved therapists were added and subsequently integrated to the intervention 'AanTafel!' (Step V). 'AanTafel!' is a multi-component, multi-disciplinary, family-based, parent-focused, age-specific intervention, which is tailored to individual children and families with a duration of 1 year, and using a combination of individual and group sessions as well as a Web-based learning module. Changes in scientific working principles with regard to data collection, reporting and translation to guidelines are required. Practice and science may benefit from close collaboration in designing, implementing and evaluating interventions.

[IC triage in patients with an acutely worsening condition; challenges, considerations and decisions]. / IC-triage bij de acuut verslechterende patiënt.

Acute intensive care (IC) triage involves a challenging decision-making process. Physicians are required to make life or death decisions about an unfamiliar patient within a short time frame. An 84-year-old female was admitted to the stroke unit following an extensive cerebral infarction. The intensive care unit (ICU) physician was consulted because of a suspected severe abdominal sepsis even though ICU treatment had never previously been discussed. A 77-year-old female with a previous history of myocardial infarction and severe COPD developed acute respiratory failure on the ward, and was admitted to the ICU for support by a mechanical ventilator. The family felt this was an inappropriate course of treatment, considering her former poor quality of life. When physicians are confronted with sudden deterioration of the patient's clinical condition without advanced care planning a limited-time IC treatment trial is often initiated, possibly leading to inappropriate ICU admissions. ICU treatment options should preferably be discussed beforehand; preliminary background information regarding the patient's wishes is essential for adequate decision-making.

The efficacy of guided self-instruction for patients with idiopathic chronic fatigue: A randomized controlled trial.

OBJECTIVE: To determine the efficacy of a cognitive-behavioral intervention for patients meeting U.S. Centers for Disease Control and Prevention (CDC) criteria for idiopathic chronic fatigue (ICF). ICF is thought to be a less severe disorder than chronic fatigue syndrome (CFS). The intervention consisted of a booklet with self-instructions combined with e-mail contact with a therapist. METHOD: Randomized controlled trial conducted at an outpatient facility. All patients suffered from severe and persistent fatigue with moderate impairment levels or fewer than 4 additional symptoms. Patients were randomly allocated to either guided self-instruction or a wait-list control group. Primary outcome measures were fatigue severity assessed with the Checklist Individual Strength and level of overall impairment assessed with the Sickness Impact Profile. Outcome measures were assessed prior to randomization and following treatment or wait-list control group. RESULTS: One hundred patients were randomly allocated to the intervention or a wait-list control group and 95 completed second assessment. An intention-to-treat analysis showed significant treatment effects for fatigue severity (-8.98, 95% confidence interval [CI] [-13.99, -3.97], Cohen's d = 0.68, p < .001) and for overall impairment (-317.19, 95% CI [-481.70, -152.68], Cohen's d = 0.53, p < .01) in favor of the intervention. The number of additional symptoms and overall impairment at baseline did not moderate posttreatment fatigue severity. Baseline overall impairment moderated posttreatment impairment. CONCLUSIONS: Patients with ICF can be treated effectively with a minimal intervention. This is relevant as ICF is more prevalent than CFS and treatment capacity is limited.

Vitamin D deficiency as adverse drug reaction? A cross-sectional study in Dutch geriatric outpatients.

PURPOSE: Adverse drug reactions as well as vitamin D deficiency are issues of public health concern in older people. However, relatively little is known about the impact of drug use on vitamin D status. Our primary aim is to explore associations between drug use and vitamin D status in older people. Furthermore, prevalences of drug use and vitamin D deficiency are estimated. METHODS: In a population of 873 community-dwelling Dutch geriatric outpatients, we explored the cross-sectional relationships of polypharmacy (≥5 medications concomitantly used), severe polypharmacy (≥10 medications), and use of twenty-one specific drug groups, with serum 25-hydroxyvitamin D (25(OH)D) by analysis of covariance. RESULTS: Overall prevalence of polypharmacy was 65 %, of severe polypharmacy 22 %. Depending on the cut-off value, prevalence of vitamin D deficiency was 49 % (<50 nmol/l) or 77 % (<75 nmol/l). Of the patients using a vitamin D supplement, 17 % (<50 nmol/l) or 49 % (<75 nmol/l) were still deficient. In non-users of supplemental vitamin D, after adjustment for age and gender, negative associations were found for severe polypharmacy, metformin, sulphonamides and urea derivatives (SUDs), vitamin K antagonists, cardiac glycosides, loop diuretics, potassium-sparing diuretics, ACE inhibitors, and serotonin reuptake inhibitors; for non-selective monoamine reuptake inhibitors (NSMRIs) the association was positive. The most extreme impacts of drug use on adjusted mean 25(OH)D were -19 nmol/l for SUDs and +18 nmol/l for NSMRIs. CONCLUSION: Drug use should be considered a risk factor for vitamin D deficiency amongst geriatric outpatients.

Quality of life in chronic illness: children, parents and paediatricians have different, but stable perceptions.

AIM: Quality of life assessments can be helpful to estimate the well-being of chronically ill children. The aim of this study was to investigate the differences in perception of health-related quality of life (HRQoL) among children, parents and paediatricians at the time of diagnosis and after initial treatment in four chronic diseases. METHODS: HRQoL was assessed with the Health Utilities Index mark 3 (HUI3). The HUI3 consists of eight attributes (vision, hearing, speech, ambulation, dexterity, emotion, cognition and pain). RESULTS: Nineteen paediatricians and 60 patients (aged 10-17 years) and their parents with newly diagnosed acute lymphoblastic leukaemia, juvenile idiopathic arthritis, asthma or with cystic fibrosis admitted for pneumonia participated in the study. Health and well-being perceptions were clearly different among paediatricians, parents and patients, both at diagnosis and after initial treatment. Perception differences were more prominent in the subjective attributes, emotion and pain. The agreement for these attributes was 23% and 5%, respectively. Paediatricians assessed the patients to have less pain than the patients and parents did. The reverse was true for the attribute emotion. At follow-up, the agreement was higher for the attributes ambulation and pain. CONCLUSION: At the onset of a chronic disease and after initial treatment, paediatricians, parents and children have different perceptions of the child's quality of life, particularly as to the subjective attributes pain and emotion. In view of these differences in perception among patients, their caregivers and paediatricians, this study suggests that whenever possible, multi-respondent assessment of HRQoL should be considered.

Limited use of medicinal cannabis but for labeled indications after legalization.

Since September 2003, cannabis is available for medicinal purposes in Dutch pharmacies to. It was anticipated that the medicinal cannabis use via illegal ways would decrease. The objective of this study was to get insight in the use of medicinal cannabis in daily practise as dispensed by community pharmacies and to characterize the users as well as the symptoms and conditions cannabis is prescribed for.A prospective follow-up study among 200 patients who filled a prescription for medicinal cannabis was performed in the period between September 2003 and January 2004. The patients filled out a structured questionnaire concerning symptoms and conditions and their experience with cannabis. Of all patients, 42% suffered from multiple sclerosis, 11% suffered from rheumatic diseases, and 60% of respondents already used cannabis before the legalization. Cannabis was mainly used for chronic pain and muscle cramp/stiffness.The indication of medicinal cannabis use was in accordance with the labeled indications. However, more than 80% of the patients still obtained cannabis for medicinal purpose from the illegal circuit. Because of the higher prices in pharmacies, ongoing debate on the unproven effectiveness of the drug and the hesitation by physicians to prescribe cannabis.

The old lady who liked liquorice: hypertension due to chronic intoxication in a memory-impaired patient.

The authors report an 85-year-old patient admitted because of cognitive impairment. During examination hypertension and hypokalaemia were found. After some time it was discovered that the patient was eating too much liquorice. The case demonstrates that liquorice intoxication should be considered as a cause of hypertension in old age. Furthermore the case demonstrates that missing an intoxication is a pitfall for medical history taking of patients with cognitive impairment.

Quality of life in chronic illness: perceptions of parents and paediatricians.

AIMS: To investigate the differences in perception of quality of life between parents of chronically ill children and paediatricians at diagnosis and follow up. Quality of life was assessed using the (HUI3). METHODS: Longitudinal study (July 1999-January 2002) of 37 paediatricians and 181 parents of patients (children aged 1-17 years) with cystic fibrosis admitted for a pneumonia or patients with newly diagnosed acute lymphatic leukaemia, juvenile idiopathic arthritis, or asthma. Main outcome measure was percentage agreement on the attributes of the HUI3 between parents and paediatricians. RESULTS: Differences in perception of health and wellbeing between paediatricians and parents of children with a chronic disease were found, not only at diagnosis but also after a period of follow up. Differences were particularly clear in the subjective attributes emotion (range of agreement 28-68%) and pain/discomfort (range of agreement 11-33%). In all patient groups, at baseline and follow up, the paediatrician assessed the patient to have less pain/discomfort in comparison to the parents. Despite a prolonged patient- paediatrician relationship, differences at follow up did not decrease compared to baseline. CONCLUSION: At the onset of a chronic disease, but also after a period of follow up, quality of life of paediatric patients may be misunderstood by healthcare professionals, especially in the subjective attributes. Systematic assessment of quality of life may contribute to better understanding between physicians and parents.

A difference in perception of quality of life in chronically ill children was found between parents and pediatricians.

BACKGROUND AND OBJECTIVES: Quality of life measurements can help to estimate the well-being of chronically ill patients, and disclose discrepancies in perception between physicians and patients that might otherwise interfere with the effectiveness of treatment. The objective was to investigate the differences in perception of quality of life between parents of chronically ill children and pediatricians. METHODS: A cross-sectional study was conducted in four tertiary pediatric care centers in The Netherlands. The Health Utilities Index mark 3 (HUI3) was used by 37 pediatricians and 279 parents of patients (children aged 1 to 17 years) with cystic fibrosis admitted either in daycare or for a pneumonia, or patients with newly diagnosed acute lymphoblastic leukemia, juvenile idiopathic arthritis, or asthma. RESULTS: Differences in perception of quality of life between parents and pediatricians appeared to be dependent of the disease. In patients with acute lymphoblastic leukemia (OR 7.4; [95% CI 2.88-18.97], juvenile idiopathic arthritis (4.7; [95% CI 2.00-11.22]), and asthma (2.3; [95% CI 1.13-4.69]) a difference in perception was more likely to occur than in patients with cystic fibrosis admitted in daycare. CONCLUSION: At the onset of a chronic disease, the parents of pediatric patients may be misunderstood by health care professionals, especially in subjective attributes. Assessment of quality of life may contribute to better understanding between pediatricians and parents, and thus may even enhance compliance and treatment effects.

Quality of life: patients and doctors don't always agree: a meta-analysis.

OBJECTIVE: In addition to traditional clinical markers, quality-of-life assessment can be helpful to estimate the well-being of patients. Discrepancies in perception of well-being between physicians and patients may interfere with the effectiveness of treatment. A systematic review and meta-analysis were performed to explore the (dis-)agreement in quality-of-life assessments between patients and physicians. STUDY DESIGN AND SETTING: Data on the proportion agreement of paired observations were collected from Medline, Embase, Psychlit, and Social Abstracts. RESULTS: Of the 1,316 articles found, six met the selection criteria, four studied the proportion agreement between children and physicians, and all six the proportion agreement between parents and physicians. None examined the magnitude of over- or underestimation by physicians. The agreement was lower in the more subjective domains (0.54-0.77) in comparison to the more objective domains (0.79-0.94). CONCLUSION: Quality-of-life assessment should be integrated in clinical practice. During long-term treatment the perception of the patients' well-being by physicians and patients themselves can easily diverge from each other, resulting in misunderstandings about the treatment and its usefulness in relation to perceived quality of life, and may even become the base for noncompliance.

Neurofibromatosis type 2 diagnosed in the absence of vestibular schwannomas. A case report and guidelines for a screening protocol for children at risk.

UNLABELLED: A 5-year-old girl presented with multiple tumours of the central nervous system. As on the first MRI scan bilateral vestibular schwannomas were not detected due to their small size, she initially did not meet the criteria for neurofibromatosis type 2 (NF2), although her clinical symptoms were highly suggestive for the diagnosis. Using molecular studies, a mutation in the NF2 gene was found confirming the clinical suspicion at an early age and indicating the value of molecular analysis. Follow-up MRI 3 years later demonstrated bilateral vestibular schwannomas more clearly, since they had increased in size. CONCLUSION: In children, magnetic resonance imaging can be inconclusive for the diagnosis of neurofibromatosis type 2, since very small vestibular schwannomas may be missed. In these cases molecular studies may provide additional evidence for the diagnosis. We propose guidelines for a screening protocol for children at risk for having neurofibromatosis type 2.

Determination of stroke volume by means of electrical impedance tomography.

ECG-gated electrical impedance tomography (EIT) is a non-invasive imaging technique, developed to monitor blood volume changes. This study is the first in comparing this non-invasive technique in measuring stroke volume with established techniques. The objective of this study was to validate EIT variables derived from the EIT images with paired obtained stroke volume measurements by thermodilution and MRI. After right cardiac catheterization, EIT measurements were performed in 25 patients. Regression analysis was used to analyse the relation between the EIT results and stroke volume determined by thermodilution. From the regression line an equation was derived to estimate stroke volume (in ml) by EIT. A strong correlation was found between EIT and stroke volume measured by the thermodilution method (r = 0.86). In a group of 11 healthy subjects this equation was validated to MRI. The mean and standard deviation of the difference between EIT and MRI was 0.7 ml and 5.4 ml respectively. These data indicate that EIT is a valid and reproducible method for the assessment of stroke volume.

Pulmonary perfusion measured by means of electrical impedance tomography.

Electrical impedance tomography (EIT) is a recent imaging technique based on electrical impedance, offering the possibility of measuring pulmonary perfusion. In the present study the influence of several pulmonary haemodynamical parameters on the EIT signal were investigated. First, the influence on the systolic wave of the EIT signal (delta Zsys) of stroke volume, large pulmonary artery distensibility (both assessed by means of MRI) and the extent of the pulmonary peripheral vascular bed in 11 emphysematous patients (reduced peripheral vascular bed) and 9 controls (normal peripheral vascular bed) was investigated. Second, the influence of hypoxic pulmonary vasoconstriction on delta Zsys was examined in 14 healthy subjects. Finally, the origin of the diastolic wave was examined in three patients with atrioventricular dissociation. Multiple regression analysis showed that delta Zsys was only dependent on the variable emphysema (p < 0.02), but not dependent on stroke volume (p < 0.3) or pulmonary artery distensibility (p > 0.9). The mean value of delta Zsys for emphysematous patients (131 +/- 32 arbitrary units (AU)) was significantly lower (p < 0.001) than in the control group (200 +/- 39). In the group of healthy subjects delta Zsys decreased significantly (p < 0.001) during hypoxia (193 +/- 38 AU) compared with rest measurements (260 +/- 62 AU). The absence of the diastolic wave in the cardiological patients suggests the influence of reverse venous blood flow on the EIT signal. It is concluded that volume changes in the small pulmonary vessels contribute significantly to the EIT signal. Moreover, the hypoxia induced decrease in delta Zsys indicates the potential of EIT for measuring pulmonary vascular responses to external stimuli.

Sagittal position of the left and right maxillary segment in children with cleft lip and palate.

OBJECTIVE: The purpose of the present study was to investigate left-right differences in the sagittal position of the maxillary segments in children with cleft lip and palate. METHOD: The sample consisted of children with operated cleft lip or cleft lip and alveolus [CL/CLA (n = 16) mean age, 9.3 yr], operated unilateral cleft lip and palate [UCLP (n = 27) mean age, 9.1 yr], and operated bilateral cleft lip and palate [BCLP (n = 17) mean age, 9.5 yr]. Computed tomography (CT) horizontal slices of the maxilla were obtained and used to determine the sagittal position of the left and right segment of the maxilla in relation to the mandibular rami and the cranial base. Significant effects were analyzed with multivariate analyses of variance (MANOVA). RESULTS AND CONCLUSIONS: It was concluded that, in contrast to children having CL/CLA or UCLP, children with BCLP showed left-right differences in the sagittal position of the maxillary segments. The segment on the left side was more posteriorly positioned compared to the right side. Because the same results were obtained in relation to the mandibular rami as well as in relation to the cranial base, it can be assumed that the position of these rami are not affected by the different types of oral clefts.

Noninvasive assessment of right ventricular diastolic function by electrical impedance tomography.

STUDY OBJECTIVES: Electrical impedance tomography (EIT) offers the possibility to study blood volume changes within the right atrium during the cardiac cycle. The aim of this study was to determine the applicability of EIT in the assessment of right ventricular diastolic function in COPD. DESIGN: By means of region of interest analysis, impedance changes within the right atrium during the cardiac cycle were plotted as a function of time. As a diastolic index of the right ventricle, the right atrium emptying volume (RAEV), defined as the ratio between the volume change during the rapid filling phase relative to the total ventricular filling volume, was calculated. In a first study, the validity of the EIT method was assessed by comparison of the RAEV measured by EIT and MRI in a group of eight patients with severe COPD and seven control subjects. A second study was undertaken to assess the relation between RAEV and pulmonary artery pressure in a group of 27 patients measured by right-sided heart catheterization. RESULTS: The correlation coefficient between RAEV measured with MRI and EIT was 0.78. The difference between RAEV measured by MRI and EIT was 8.3 +/- 15.7% (mean +/- SD) for the control subjects and 3.5 +/- 10.9% for the COPD patients. RAEV values measured by EIT and MRI were larger in the control group (47.1 +/- 7.6%) compared with the patient group (38.1 +/- 10.4%). There was a clear nonlinear relationship between RAEV and the pulmonary artery pressure (y = 315 x-0.64, r = 0.83, p < 0.001). CONCLUSION: Our results indicate that RAEV measured by EIT is a useful noninvasive and inexpensive method for assessing right ventricular diastolic function in COPD patients.

Validity and reproducibility of electrical impedance tomography for measurement of calf blood flow in healthy subjects.

The Sheffield electrical impedance tomography; (EIT) system produces images of changes in the distribution of resistivity within tissue. The paper reports on the application of electrical impedance tomography in monitoring volume changes in the limb during venous occlusion. The aim of the study is to assess the feasibility, reproducibility and validity of calf blood flow measurements by EIT. In 14 healthy volunteers calf blood flow is compared, as determined in a calf segment by strain-gauge plethysmography (SGP), with the impedance changes measured by EIT during rest and post-ischaemic hyperaemia. The measurements are repeated to assess reproducibility. The reproducibility for the EIT, assessed from the repeated measurements and expressed as a reproducibility coefficient, is 0.88 during rest and 0.89 during hyperaemia. The reproducibility coefficient for SGP data is 0.83 at rest and 0.67 during hyperaemia. Flow measurements, assessed by means of two methods, correlate well at rest (r = 0.89), but only moderately during hyperaemia (r = 0.51). The correlation coefficient for the pooled flow measurements is 0.98. It is concluded that EIT is a valid and reliable method for assessing blood flow in the limb. Possible applications of EIT in localising fluid changes are discussed.