Non-invasive Function Tests Research Articles

Hyperemic maximal venous outflow unmasks symptomatic lower extremity venous obstruction

Venous obstruction is an underappreciated and often unrecognized component of the pathophysiology of symptomatic chronic venous disease (CVD). Moreover, standard methods used to detect venous obstruction, such as maximal venous outflow, are inadequate as they typically test patients at rest and in the supine position when the pathophysiology of CVD is defined in the upright patient performing exercise. This report describes a patient with incapacitating venous claudication in whom standard noninvasive venous function tests were normal and whose phlebography was interpreted as showing no evidence of venous obstruction. A postocclusive reactive hyperemic technique was used to unmask significant outflow obstruction, leading to operative correction and subsequent symptom resolution.

Intermittent Positive-Pressure Breathing Effects in Patients With High Spinal Cord Injury

Laffont I, Bensmail D, Lortat-Jacob S, Falaize L, Hutin C, Le Bomin E, Ruquet M, Denys P, Lofaso F. Intermittent positive-pressure breathing effects in patients with high spinal cord injury. Objective To determine whether intermittent positive-pressure breathing (IPPB) improved lung compliance, work of breathing, and respiratory function in patients with recent high spinal cord injury (SCI). Design An unblinded randomized crossover trial. Setting Rehabilitation hospital. Participants Patients (N=14) with SCI caused by trauma within the last 6 months and located between C5 and T6. Intervention Two months of IPPB and 2 months of conventional treatment were evaluated prospectively in random order in patients with SCI. Main Outcome Measures Noninvasive lung function tests and arterial blood gas measurements were obtained repeatedly in all patients. Repeated measurements of dynamic lung compliance and work of breathing as measured by computing the area enclosed between the inspiratory esophageal pressure-tidal volume curve, and the theoretical chest wall static pressure-volume curve were performed in 7 patients. Results IPPB had no long-term effects on vital capacity (52.1%±11.3% vs 54.5%±12.5%, after conventional treatment and IPPB, respectively; P=.27), lung compliance (66.4±48.9mL/cmH 2O vs 70.3±38.4mL/cmH 2O; P=.56), or other lung function tests. IPPB did not exert short-term effects on lung compliance or work of breathing. Conclusions IPPB produced no immediate or long-term improvements in lung function or ventilatory mechanics in patients with recent SCI. ( ClinicalTrials.gov identifier: NCT00476866.)

Asthma as a nonlinear complex dynamic system: a novel approach to understand the temporal behaviour of chronic asthma and its response to β-agonists

I am a paediatric pulmonologist, Professor and Head of the Division of Paediatric Respiratory Medicine at the University Children's Hospital in Bern, Switzerland. I graduated in 1989, wrote my MD thesis in paediatrics and trained as a paediatrician in Bern. I then spent some time in research and clinical training at Boston University (Boston, MA, USA), Hammersmith Hospital (London, UK) and Leicester University (Leicester, UK) and wrote a PhD in medical physics/biomedical engineering. My major research interests include the developmental physiology of newborns with wheezing disorders and asthma, and the potential role of environmental pollutants in lung growth and development. I was also involved in the development of new noninvasive lung function and nitric oxide measurement tests in infants. Such tests can be carried out in unsedated infants during natural sleep, and facilitate lung function studies in larger healthy cohorts and early recognition of infants at risk for later wheezing disorders and asthma. I was also significantly involved in the European Respiratory Society (ERS)/American Thoracic Society standardisation of infant lung function testing. My research has been supported by the Swiss National Science Foundation and by ERS long-term research fellowships. In 1999, I won the ERS Paediatric Respiratory Research in Europe Award and, in 2003, the Swiss Theodor-Kocher Research Award. The structure as well as the function of the respiratory system is complex. It includes subsystems involved in host defence, immunity and inflammation, as well as lung mechanics; these are inhomogeneous and irregular. More importantly, none of these subsystems function independently of each other but are highly interlinked, constituting a network with various tiers ranging from the molecular through cellular to organ level. Additional interactions occur within the organism, as well as within the external environment. Most studies that have led to advances in the understanding of the pathophysiology of the …

Computerized mouse pupil size measurement for pupillary light reflex analysis

Accurate measurement of pupil size is essential for pupillary light reflex (PLR) analysis in clinical diagnosis and vision research. Low pupil–iris contrast, corneal reflection, artifacts and noises in infrared eye imaging pose challenges for automated pupil detection and measurement. This paper describes a computerized method for pupil detection or identification. After segmentation by a region-growing algorithm, pupils are detected by an iterative randomized Hough transform (IRHT) with an elliptical model. The IRHT iteratively suppresses the effects of extraneous structures and noise, yielding reliable measurements. Experimental results with 72 images showed a mean absolute difference of 3.84% between computerized and manual measurements. The inter-run variation for the computerized method (1.24%) was much smaller than the inter-observer variation for the manual method (7.45%), suggesting a higher level of consistency of the former. The computerized method could facilitate PLR analysis and other non-invasive functional tests that require pupil size measurements.

Pulmonary Radioaerosol Mucociliary Clearance in Diagnosis of Primary Ciliary Dyskinesia

Methods relying on nasal ciliary motility for the diagnosis of primary ciliary dyskinesia (PCD) are often hampered by secondary ciliary dyskinesia. A functional test for pulmonary mucociliary clearance, which is not influenced by secondary nasal ciliary defects, would be a valuable tool in a PCD workup. The diagnostic validity and repeatability of a pulmonary radioaerosol mucociliary clearance (PRMC) test for the diagnosis of PCD was assessed in the following three sequentially performed substudies: (1) a preliminary cross-sectional study of PRMC in patients with known PCD; (2) a prospective blinded trial of patients referred for suspicion of PCD; and (3) an implementation study of PRMC as a routine method used in a PCD workup. PRMC was studied after (99m)Tc-albumin colloid aerosol inhalation, and the results were compared to (1) the results of nasal ciliary motility studies, (2) ciliary ultrastructure, and (3) the final clinical diagnosis. The repeatability of PRMC was assessed in 14 patients. A total of 95 patients, 5 to 74 years of age, were included in the study (57 patients in whom PCD was diagnosed, 26 non-PCD patients, and 12 patients referred for PCD workup without a conclusive workup result). In substudy 1, 14 of 15 patients with known PCD showed impaired PRMC; the results were inconclusive in 1 patient. In substudy 2, among 59 patients referred for PCD workup PRMC test results, compared to nasal ciliary motility, showed a sensitivity of 88% and a specificity of 100%. In substudy 3, among 21 patients referred for PCD investigation who were included in a routine PCD workup after PRMC implementation, 71% of PRMC test results were in alignment with nasal ciliary motility. Repeatability of interpretation was seen in 13 of 14 cases. A conclusive PRMC after only one test was found in 81 of 95 patients (85%). PRMC is a noninvasive functional test for total tracheobronchial mucociliary clearance with a high sensitivity and specificity for PCD, a high rate of conclusive results after only one test and a further ability to separate PCD from focal pulmonary mucociliary defects.

Correlation of MRCP quantification (MRCPQ) with conventional non-invasive pancreatic exocrine function tests

To correlate MRCP quantification (MRCPQ) of pancreatic fluid output following secretin with steatorrhoea, urinary pancreo-lauryl (PL) or fecal elastase 1 (FE1) tests. Sixty-one patients, 36 male, median age 51 years (23-78) with known or suspected pancreatic disease who had undergone both MRCPQ and FE1 or PL were included. Twenty-nine patients had chronic pancreatitis, five acute pancreatitis, seven normal, five pancreas divisum, four pancreatic atrophy, three pancreatic duct obstruction, two post-surgical and six miscellaneous diagnoses. Clinical assessment of steatorrhoea was available in 29. MRCP was performed before and at 2 min intervals after 0.1 ml/kg IV Secretin. Changes in signal intensity in the imaging volume were plotted against time and the flow rate derived from the gradient. Scatter plots, Pearson correlation coefficient, and the Fisher Exact test were performed. MRCPQ was significantly different (p = 0.012) between those with/without steatorrhoea; mean +/- SD (95% CI) were 4.0 +/- 1.5 (3.1:4.9, n = 16) and 6.3 +/- 2.9 (4.7:7.8, n = 13). Fifty-one paired FE1-MRCPQ and 24 PL-MRCPQ data sets were analysed. Both the Pearson correlation coefficient (FE1 p = 0.001 and %TK p = 0.003) and the Fisher Exact test were significant (FE1 p = 0.016 and %T/K 0.03). MRCPQ correlated with steatorrhoea, PL and FE1.

Quantitative secretin MRCP (MRCPQ): results in 215 patients with known or suspected pancreatic pathology

Secretin magnetic resonance cholangiopancreatography quantification (MRCPQ) of pancreatic exocrine function correlates well with steatorrhoea and conventional, non-invasive function tests. We report MRCPQ results in a variety of pancreatic conditions. A total of 215 patients [107 male, mean age 46 years (14-78)] were studied. A multi-slice MRCP sequence was performed before and at 2-min intervals after 0.1 ml/kg IV secretin. Change in small intestinal water volume was plotted against time and the flow rate derived from the gradient. Patients were classified using clinical history, MRCP, MR imaging, computed tomography (CT) [150/215 (70%)] and endoscopic retrograde cholangiopancreatography (ERCP) [56/215 (26%)] findings but not MRCPQ results. Mean, standard deviation and 95% confidence intervals were calculated. The one way ANOVA and Student's t-test were used for statistical analysis. Seventy-six patients had chronic pancreatitis, 26 were post-surgical, 34 post-acute pancreatitis, six atrophic pancreatopathy, eight with obstruction, 15 divisum, ten sphincter of Oddi dysfunction, 26 normal and 14 miscellaneous. Significant differences were observed between normals (mean+/-SD; 7.4 +/- 2.9 ml/min) and severe chronic pancreatitis (5.3 +/- 2.4) (P = 0.018), pancreatic atrophy (3.8 +/- 3.1) (P = 0.013) or duct obstruction (5.3 +/- 2.4) (P = 0.047)) and between moderate (7.0 +/- 3.0) (P = 0.03) and severe chronic pancreatitis. MRCPQ can be used to quantify function across the spectrum of pancreatic disease and showed significant differences between several different pathologies.

13C-MIXED TRIGLYCERIDE BREATH TEST (13C-MTG) DEMONSTRATES SUPERIORITY OF ENTERIC COATED MONOLITHIC ENZYME PREPARATION OVER PLACEBO

Background: Currently, no non-invasive pancreatic function tests are broadly available apart from fecal elastase-1 (El-1) which has limited sensitivity and specificity. We applied the 13C-MTG for measurement of the effects of a monolithic enteric coated enzyme preparation (i.e. single unit, no microgranules) on lipid digestion and absorption. Due to dissociation between gastric emptying of meal nutrients and enzyme supplements, these older preparations are assumed to be virtually ineffective and potential effects can only be shown by sensitive methods. Methods: 20 patients with documented chronic pancreatitis (19 males, 1 female, age: 52±2 yrs, BMI: 23.1±0.7 kg/m2, El-1: 42.1±8.2 μg/g, mean-SEM) were included in 3 study centres. On two study days which were 3-14 days apart and each preceeded by at least 3 days without intake of enzyme supplements, patients received a monolithic enteric-coated pancreatin preparation (40,000 U of lipase) or placebo together with a standardised test meal containing 250 mg of 13C-mixed triglycerides according to a randomised, double blind, cross-over study design. Differences between cumulative 13C-exhalation were evaluated as markers of lipid digestion during treatment with verum and placebo. Results: (mean±SEM, statistics: ANOVA): One patient had to be excluded because of major protocol violations; 6 patients were excluded from the per protocol analysis because of normal intestinal lipolysis during placebo treatment despite decreased El-1. In the remaining 13 patients, mean cumulative 13C-exhalation over 6 and 8 hours was markedly higher following treatment with verum compared to placebo (6 h: 11±2 vs. 5±1% of dose, p = 0.035; 8 h: 18±3 vs. 9±1% of dose, p = 0.015). Conclusions: In contrast to current belief, single administration of a monolithic enteric-coated pancreatin preparation containing 40,000 U of lipase significantly improves lipid digestion and absorption compared to placebo in patients with severe pancreatic exocrine insufficiency. Sensitivity of the 13C-MTG allows detection of these effects and, thus, this non-invasive test may expand our diagnostic armamentarium in pancreatic exocrine insufficiency.

Invasive and noninvasive lung function measurements in rodents

Precise and repeatable measurements of pulmonary function in intact mice or rats are becoming increasingly important for experimental investigations on various respiratory disorders like asthma and for pharmacological, safety-pharmacological or toxicological testing of drugs or chemicals. This review provides a short overview of typical in-vivo measurement techniques, discusses their advantages and disadvantages and presents two of these methods in detail: the noninvasive head-out body plethysmography and an invasive but repeatable body-plethysmography in orotracheally intubated rodents. It will be demonstrated that these methods are able to monitor bronchoconstriction in safety-pharmacological tests or in asthma models showing early allergic response or late airway hyperresponsiveness in response to inhaled allergens and demonstrate drug effects on pulmonary endpoints. The changes in the respective parameters such as tidal midexpiratory flow (EF 50) or lung resistance in typical bronchoconstriction models have been measured in the same animals and compared for validation purposes. It is concluded that both invasive and noninvasive pulmonary function tests are capable of detecting allergen-specific as well as non-allergic bronchoconstriction in intact mice or rats. The invasive determination of resistance is superior in sensitivity, whereas the noninvasive EF 50 method is particularly appropriate for quick and repeatable screening of respiratory function in large numbers of mice and rats or if the conscious animal has to be tested (e.g. safety pharmacology). The use of both techniques in a large number of studies in the last years have demonstrated that they provide useful and necessary information on pulmonary mechanics in studies of respiratory disorders including experimental models of asthma, in investigations of pulmonary pharmacology, safety pharmacology and toxicology in mice and rats.

New developments in lung function measurements in rodents

There are invasive and noninvasive pulmonary function tests available which are sensitive in detecting bronchoconstriction in rodents. Noninvasively measured midexpiratory flow (EF 50) has been shown to be an appropriate parameter to monitor bronchoconstriction in a large number of animals, e.g. for screening purposes. Recently, a novel technique for repetitive lung function measurements in orotracheally intubated, spontaneously breathing mice has been established. Bronchoconstriction is assessed by the “gold standard” parameters airway resistance and dynamic compliance in response to aerosolized methacholine or allergens in anesthetized mice. This measurement technique has been combined with an inhalation technique which has been optimized to allow simultaneous lung function measurement in intubated animals and to obtain high aerosol concentrations. A feedback dose control system has been developed to administer a defined and constant aerosol dose to each individual animal. Using this system a prominent early allergic response and late airway hyperresponsiveness could be demonstrated in intubated mice challenged with Aspergillus fumigatus allergen. We conclude: The noninvasive EF 50 method seems particularly appropriate for measurements of respiratory function in large numbers of conscious mice in assembly line fashion. The invasive technology – newly established for the mouse – is more sensitive and specific since true airway resistance and dynamic compliance are determined and allows now the adequate detection of an early allergic response in the mouse and also repetitive measurements e.g. to assess the airway hyperresponsiveness in the same animal or for monitoring purposes in chronic models.

Prediction of Post-Operative Glomerular Filtration Rate After Nephrectomy for Renal Malignancy

The importance of a correct estimation of contralateral renal function in cases of renal malignancy is obvious, necessitating a conservative approach to tumour resection when function of the contralateral kidney is markedly reduced. The aim of the present study was to determine the accuracy of preoperative gamma camera renography and (51)Cr-EDTA clearance to predict the glomerular filtration rate (GFR) early and up to 6 months after nephrectomy for renal malignancy. Patients (n=40) underwent both gamma camera renography ((99m)TC-DTPA) and (51)Cr-EDTA clearance preoperatively, whereas (51)Cr-EDTA clearance was measured within 1 week and up to 6 months after nephrectomy. The single kidney GFR values of the contralateral kidneys were estimated preoperatively and then compared with the post-operative (51)Cr-EDTA clearance values. The predicted GFR values were lower compared with the measured post-operative (51)Cr-EDTA clearance values (45 +/- 2 vs. 54 +/- 3 ml min(-1) 1 week after nephrectomy and 53 +/- 3 ml min(-1) 6 months later, P 30% by the tumour affected kidney. Prediction of post-operative GFR by non-invasive renal function tests performed prior to surgery for renal malignancy underestimate post-operative GFR when the function of the tumour affected kidney is preserved, indicating an adaptive GFR increase in these cases.

Evaluation of Type 1 Diabetics for Simultaneous Pancreas-Kidney Transplantation With Regard to Cardiovascular Risk

The main cause of death for diabetic patients and patients on dialysis is coronary artery disease (CAD). The most common cause of graft loss following simultaneous pancreas and kidney transplantation (SPK) is death with a functioning graft due to CAD. Therefore, careful pretransplantation evaluation of CAD is mandatory. In our series, every patient undergoes a noninvasive cardiac function test like dobutamine stress echocardiography (DSE) or myocardial thallium scintigraphy using adenosine to induce medical stress. Thirty patients were evaluated for SPK: 15 patients with myocardial scintigraphy and 8 with DSE. Seven investigations showed pathological findings and we performed coronary angiograms, none of which showed coronary artery stenosis. Seven primary coronary angiograms were performed: four due to a history of CAD and three as a primary diagnostic. Following SPK one patient died at 21 days after transplantation due to myocardial infarction. He had a history of CAD with angioplasty and stent implantation. Noninvasive cardiac function tests like DSE or myocardial scintigraphy are reliable methods to evaluate CAD in patients with diabetic nephropathy awaiting SPK. In case of a suspicious finding or a history of CAD, a coronary angiogram should be performed to assess the need for revascularization. Following this algorithm we may further reduce the mortality of SPK.

Invasive versus noninvasive measurement of allergic and cholinergic airway responsiveness in mice

BackgroundThis study seeks to compare the ability of repeatable invasive and noninvasive lung function methods to assess allergen-specific and cholinergic airway responsiveness (AR) in intact, spontaneously breathing BALB/c mice.MethodsUsing noninvasive head-out body plethysmography and the decrease in tidal midexpiratory flow (EF50), we determined early AR (EAR) to inhaled Aspergillus fumigatus antigens in conscious mice. These measurements were paralleled by invasive determination of pulmonary conductance (GL), dynamic compliance (Cdyn) and EF50 in another group of anesthetized, orotracheally intubated mice.ResultsWith both methods, allergic mice, sensitized and boosted with A. fumigatus, elicited allergen-specific EAR to A. fumigatus (p < 0.05 versus controls). Dose-response studies to aerosolized methacholine (MCh) were performed in the same animals 48 h later, showing that allergic mice relative to controls were distinctly more responsive (p < 0.05) and revealed acute airway inflammation as evidenced from increased eosinophils and lymphocytes in bronchoalveolar lavage.ConclusionWe conclude that invasive and noninvasive pulmonary function tests are capable of detecting both allergen-specific and cholinergic AR in intact, allergic mice. The invasive determination of GL and Cdyn is superior in sensitivity, whereas the noninvasive EF50 method is particularly appropriate for quick and repeatable screening of respiratory function in large numbers of conscious mice.

Endothelial Function and Early Atherosclerotic Changes

Endothelial dysfunction, including impaired vasomotor disturbance, abnormal coagulation, and increased vascular proliferation, is closely associated with the development of atherosclerosis and precedes the clinical manifestations of atherosclerosis. The impairment of endothelium-dependent vasodilation, which is chiefly attributed to decreased endothelial nitric oxide (NO) bioavailability, represents the functional characteristic of endothelial dysfunction and a early key step in the occurrence of atherosclerotic complications. An impairment of endothelial vasodilation is attributed to decreased NO production, deficiency of substrate or cofactor availability, and increased NO inactivation, and is not confined to a certain artery such as the coronary artery, but rather represents a systemic disorder that also affects peripheral vascular beds. Noninvasive endothelial function tests using extremities are a new popular method for the detection of endothelial NO bioavailability. The assessment of endothelial function detected before established atherosclerosis may be a more important risk factor to predict future atherosclerotic diseases compared with conventional risk factors such as hypertension and hyperlipidemia.

Die diagnostische Validität nichtinvasiver Pankreasfunktionstests - Eine Metaanalyse

The paper discusses the non-invasive (tubeless) pancreatic function tests used to diagnose exocrine pancreatic insufficiency (EI). Studies evaluating the diagnostic validity of these tests are integrated into a meta-analysis, provided that they comply with the following criteria: The sensitivity (Ss) of a test has to be calculated by comparing it with an invasive function test which is accepted as the gold standard of pancreatic function diagnostics. Furthermore, the test must differentiate between slight (sl), moderate (md) and severe (sv) EI. For assessment of the specificity (Sp), the control group should not contain healthy persons but rather patients with other gastrointestinal diseases and a normal pancreatic function. In the statistical evaluation, each study was weighted according to the number of persons included. Tests (n = sum of persons included in all analysed studies): Fecal chymotrypsin: Ss (n = 169) 54 % (sl EI), 53 % (md EI), 89 % (sv EI), Sp (n = 202) 74 %. NBT-PABA test: Ss (n = 394) 49 % (sl EI), 64 % (md EI), 72 % (sv EI), Sp (n = 218) 83 %. Pancreolauryl test: Ss (n = 320) 63 % (sl EI), 76 % (md EI), 94 % (sv EI), Sp (n = 171) 85 %. Fecal elastase-1: Ss (n = 307) 54 % (sl EI), 75 % (md EI), 95 % (sv EI), Sp (n = 347) 79 %. Additional tests discussed but not included in the meta-analysis were fecal fat, (13)C breath tests, amino acid consumption test, serum tests. None of the non-invasive pancreatic function tests is sensitive enough to diagnose reliably a slight to moderate exocrine pancreatic insufficiency.

P0784 INTESTINAL FUNCTION TESTS IN INTESTINAL FAILURE

Introduction: Intestinal failure (IF) is a complex condition requiring parenteral nutrition (PN). The outcome of IF is associated with its primary etiology (1) but individual prognostic factors are not available to predict weaning from PN. We tested the hypothesis that non-invasive intestinal function tests could predict weaning from PN in children with IF. Methods: IF was defined as need for total PN for at least 4 weeks or for supportive PN for at least 3 months. In children with IF we retrospectively evaluated the following non-invasive intestinal function tests: fecal steatocrit, d-xylose oral load, fecal alpha1-antitrypsin. At least 3 determinations for fecal steatocrit and 2 for d-xylose oral load were obtained. Results were analysed in relation with the primary etiology of IF. Statistical analysis was performed with non parametric and logistic regression tests, and X2 test. Results: 10 children with short bowel syndrome (SBS) and 5 with various causes of IF (NSBS) were enrolled. Fecal alpha1-antitrypsin was normal in all cases. Mean values of steatocrit were abnormal in both groups, 17 (range 0–55) and 13 (range 0–53) in children with SBS and non SBS, respectively. Xylose absorption test was significantly different in children with SBS (mean 14, range 3–35.5) versus children with NSBS (mean 26, range 16–44) (p<0.01). When we analysed steatocrit and xylose absorption in children that were eventually weaned from PN, and in those who were not, a difference was detected in SBS and NSBS children. In the latter no statistical correlation was observed between functional tests and gaining of intestinal sufficiency. In children with SBS, at enrolment, xylose absorption was statistically associated with intestinal length and weaning from PN (p<0.05), whereas such correlation was not observed for fecal steatocrit. Among functional tests, fecal steatocrit was normal in all patients weaned from PN and in 1/3 patients who could not be weaned (p=0.08). Xylose test was normal in all but 1 weaned children, and abnormal in all children who did not reach intestinal sufficiency (p<0.05). Conclusion: In children with IF and SBS fecal steatocrit and xylose absorption are markedly abnormal, and the latter correlates with residual intestinal length. Functional tests may help predicting weaning from PN. In NSBS children, only fecal steatocrit is impaired but is not associated with intestinal function.

Orthostatic Intolerance in Behcet's Disease

Neurological manifestations are known to occur in patients with Behcet's Disease (BD) and significantly affect the clinical course of the disease. Nevertheless, the prevalence, pattern and severity of autonomic impairment in such patients have yet to be defined. In this paper, we presented a BD patient with orthostatic tachycardia. Non-invasive standardized autonomic function tests revealed no evidence of autonomic impairment, but profound orthostatic tachycardia accompanied by abnormal catecholamine increase was observed upon standing. The diagnosis of Orthostatic Intolerance (OI) was made and initial symptomatic therapy was started. The contribution of an immunological damage to components of neural pathways in the pathogenesis of the autonomic involvement can be assumed.

Compound gravity receptor polarization vectors evidenced by linear vestibular evoked potentials

The utricle and saccule are gravity receptor organs of the vestibular system. These receptors rely on a high-density otoconial membrane to detect linear acceleration and the position of the cranium relative to Earth’s gravitational vector. The linear vestibular evoked potential (VsEP) has been shown to be an effective non-invasive functional test specifically for otoconial gravity receptors (Jones et al., 1999). Moreover, there is some evidence that the VsEP can be used to independently test utricular and saccular function (Taylor et al., 1997; Jones et al., 1998). Here we characterize compound macular polarization vectors for the utricle and saccule in hatchling chickens. Pulsed linear acceleration stimuli were presented in two axes, the dorsoventral (DV, ± Z axis) to isolate the saccule, and the interaural (IA, ± Y axis) to isolate the utricle. Traditional signal averaging was used to resolve responses recorded from the surface of the skull. Latency and amplitude of eighth nerve components of the linear VsEP were measured. Gravity receptor responses exhibited clear preferences for one stimulus direction in each axis. With respect to each utricular macula, lateral translation in the IA axis produced maximum ipsilateral response amplitudes with substantially greater amplitude–intensity (AI) slopes than medially directed movement. Downward caudal motions in the DV axis produced substantially larger response amplitudes and AI slopes. The results show that the macula lagena does not contribute to the VsEP compound polarization vectors of the sacculus and utricle. The findings suggest further that preferred compound vectors for the utricle depend on the pars externa (i.e. lateral hair cell field) whereas for the saccule they depend on pars interna (i.e. superior hair cell fields). These data provide evidence that maculae saccule and utricle can be selectively evaluated using the linear VsEP.

Interrupter resistance in preschool children: measurement characteristics and reference values.

There is a need for quick, reliable, and noninvasive lung function tests to assess airway obstruction in preschool children both for pediatric pulmonary care as well as for research purposes. We studied feasibility, reproducibility, and validity of measurements of the respiratory system using the interrupter technique (interrupter resistance [Rint]) and obtained reference values in children from a general population, 2 to 7 yr of age. Accuracy was studied by comparisons of Rint with plethysmographic airway resistance (Raw) in 20 patients (7 to 14 yr) with mild to severe chronic airways obstruction and was satisfactory in patients with FEV(1) > 60% predicted. The technique proved sensitive enough to detect changes in airway caliber within a small group of 12 children who developed mild respiratory tract infections. Among children from a general population, subgroups with mild respiratory symptoms or mild respiratory disease had higher mean Rint values. Airway obstruction was better detected using expiratory rather than inspiratory interruptions, both programmed at peak tidal ventilatory flow. Reproducibility within subjects was satisfactory (intraclass correlation 0.82 and 0.79). The same applied to interobserver agreement (intraclass correlation 0.98). The interrupter technique proves to be a reliable and practical test of airway function, suitable for clinical and epidemiologic studies in preschool children.

High prevalence and early onset of cardiac autonomic neuropathy among South Indian Type 2 diabetic patients with nephropathy

Objective: This study was conducted to assess the adverse effects of diabetic nephropathy on cardiovascular autonomic neuropathy (CAN) in South Indian Type 2 diabetic patients. Methods: Comparison was made between Type 2 diabetic patients with nephropathy (group 1, n=25), Type 2 diabetic patients without nephropathy (group 2, n=25) and non-diabetic, non-hypertensive control subjects ( n=20). All had a detailed clinical and biochemical work-up and cardiac assessment by ECG. Cardiac dysautonomia was assessed by a battery of five non-invasive autonomic function tests (ANF) as recommended by Ewing and Clarke [D.J. Ewing, B.F. Clarke, Diagnosis and Management of autonomic neuropathy. Br. Med. J. 285 (1982) 916–918]. Results: Group 1 patients showed a higher percentage of abnormal CAN function and a more severe form of CAN compared with patients in group 2. Group 1 patients showed early development of the abnormalities. They also had a higher prevalence of peripheral neuropathy compared with the patients without nephropathy. Conclusions: The present study showed that the presence of nephropathy was associated with the risk of cardiac autonomic neuropathy in Type 2 diabetic patients and it probably had an earlier onset also in them.