Flow-volume Parameters Research Articles

Ultrasound parameters of arteries and heart in normal fetuses

BackgroundCurrently, no normal ultrasound data of the fetuses during the 20–40 gestation have been obtained for references of fetal growth and development. If such ultrasound data existed for prenatal diagnosis of possible diseases and abnormalities, neonates would be able to get timely treatment immediately after birth. This study was thus performed to obtain ultrasound parameters of normal fetuses during the 20–40 week gestation and the distribution of ultrasound parameters with the gestational age for references of detecting potential fetal diseases and abnormalities.MethodsNormal fetuses without any abnormalities were enrolled, and the ultrasound parameters of the general biology, arteries, and aorta were measured and analyzed.Results417 normal fetuses were enrolled. A significant (P < 0.05) negative correlation with the gestational age was detected in the peak systolic velocity/peak diastolic velocity (S/D), pulsatility index (PI) and resistance index (RI) of the umbilical artery (UA). A relatively stable relationship with the gestational age was detected in the fetal weight%, S/D, PI and RI of the middle cerebral artery (MCA), peak systolic velocity (PSV) and velocity time integral (VTI) of the intra-abdominal UA, fetal heart to chest ratio, mitral valve (MV)- and tricuspid valve (TV)-E/A peak flow velocity, aortic isthmic Z-score and displacement, distance between the brachiocephalic artery-left common carotid artery (BA-LCCA) and LCCA-left subclavian artery (LSA), Z-score of aorta, ascending aorta (AAO), pulmonary artery (PA), main pulmonary artery (MPA), and descending aorta (DAO). A significant (P < 0.05) positive correlation with the gestational age was detected in the fetal biological data, MCA PSV and VTI, free-UA PSV and VTI and cardio-thoracic ratio, cardiac parameters, ductus arteriosus (DA) and isthmus diameter, aortic parameters, PA and MPA diameter, MPA PSV and VTI, isthmus flow volume and velocity and PA flow volume, DA and BA parameters, and LCCA and LSA parameters (flow volume, PSV, and VTI).ConclusionA certain correlation and distribution trend is detected in the ultrasound parameters of normal fetuses, and the ratios among different parameters remain relative stable. These findings can be used for determination of abnormal growth of the fetuses in prenatal ultrasound scan.Graphic

Colour Doppler study of blood flow in the portal vein in relation to blood flow in the milk vein, milk yield and body condition of dairy cows during dry period and lactation

In dairy cows, the liver supports the increased nutrient demands of the udder for milk production. Blood flow is key for the transport of these nutrients. This study investigated portal vein blood flow volume (PVBFVol) in relation to daily milk yield (DMY), milk vein blood flow volume (MVBFVol) and body condition parameters of high-producing dairy cows, starting from late lactation, throughout dry period, and consecutive early lactation. Seventeen repeated examinations were performed on 19 Holstein cows and 313 measurement days were finally included. Vein morphology and blood flow were examined via B-mode and spectral Doppler (triplex) ultrasonography, respectively. Body condition parameters recorded were body condition score (BCS), backfat thickness (BFT) measurement with ultrasonography, heart girth circumference (HG) and withers height (WH). Longitudinal relationship of PVBFVol with MVBFVol, DMY, BCS, BFT, HG and WH was analyzed with linear mixed models, with random intercept effects, using restricted cubic splines. A significant increase of 8.28% (p < 0.01) in PVBFVol appeared for every 1 L/min increase in MVBFVol in the univariable model. PVBFVol presented a significant negative association with BCS (p < 0.01) and BFT (p = 0.02), while interaction with production stage was significant, too. PVBFVol significantly increased by 0.38% (p = 0.04) for every 1 kg increase in DMY in the multivariable model. In conclusion, the increased PVBFVol during lactation accompanies the escalation in metabolic activity of the liver and the increased blood circulation through the udder, coping with the udder's escalating nutrient demands for milk synthesis.

Blood oxygen level dependent fMRI and perfusion MRI in the sheep brain

The ovine model could be an effective translational model but remains underexplored. Here, Blood Oxygen Level dependent functional MRI during visual stimulation and resting-state perfusion MRI were explored. We aimed at investigating the impact of isoflurane anesthesia during visual stimulation and evaluate resting cerebral blood flow and cerebral blood volume parameters in the lamb and adult sheep brain.BOLD fMRI and perfusion MRI after a bolus of DOTAREM were conducted in 4 lambs and 6 adult ewes at 3 T. A visual stimulation paradigm was delivered during fMRI at increasing isoflurane doses (1–3%).Robust but weak BOLD responses (0.21 ± 0.08%) were found in the lateral geniculate nucleus (LGN) up to 3% isoflurane anaesthesia. No significant differences were found beween BOLD responses in the range 1 to 3% ISO (p > 0.05). However, LGN cluster size decreased and functional localization became less reliable at high ISO doses (2.5–3% ISO). BOLD responses were weaker in adult sheep than in lambs (4.6 ± 1.5 versus 13.6 ± 8.5; p = 0.08). Relative cerebral blood volumes (rCBV) and relative cerebral blood flows (rCBF) were significantly higher (p < 0.0001) in lambs than in adult sheep for both gray and white matter.The impact of volatile anesthesia was explored for the first time on BOLD responses demonstrating increased reliability of functional localization of brain activity at low doses. Perfusion MRI was conducted for the first time in both lambs and adult ewes. Assessment of baseline cerebrovascular values are of interest for future studies of brain diseases allowing an improved interpretation of BOLD responses.

Tidal Breathing Measurements in Former Preterm Infants: A Retrospective Longitudinal Study

To investigate, in infants born preterm with or without bronchopulmonary dysplasia (BPD), the trajectory of tidal breathing flow-volume (TBFV) parameters in the first 2years of life; the association between TBFV parameters and perinatal risk factors; and the predictive value of TBFV parameters for rehospitalizations due to respiratory infections and wheeze. We retrospectively analyzed TBFV measurements performed at 0-6, 6-12, and 12-24months of corrected age in 97 infants <32weeks of gestation and <1500g. We assessed the association between TBFV parameters and perinatal risk-factors using linear regressions and the predictive capacity for subsequent respiratory morbidity using logistic regressions. We used the area under the curve and likelihood ratio test (LRT) to compare nested models. Time to peak tidal expiratory flow/expiratory time ratio (tPTEF/tE) was lower than normal for the first 2years of corrected age. Longer duration of oxygen supplementation, intubation, and respiratory support were associated with reduced tPTEF/tE at all time points. For each z-score increase in tPTEF/tE, the OR for rehospitalizations decreased by 0.70. tPTEF/tE added significantly to BPD classifications alone in predicting rehospitalizations (area under the receiver operating characteristic curve=0.81 vs 0.76, P value for LRT=.0012), and wheeze (area under the receiver operating characteristic curve=0.76 vs 0.71, P value for LRT <.001). Infants born preterm, with and without BPD, display persistent airway obstruction during the first 2years of life. tPTEF/tE may identify infants at greater risk of severe respiratory morbidity.

Idiopathic Normal Pressure Hydrocephalus and Elderly Acquired Hydrocephalus: Evaluation With Cerebrospinal Fluid Flow and Ventricular Volume Parameters.

PurposeTo investigate differences in cerebrospinal fluid (CSF) flow through the aqueduct and to determine whether there is a relationship between CSF flow and ventricular volume parameters in idiopathic normal pressure hydrocephalus (iNPH) patients, elderly acquired hydrocephalus patients and age-matched healthy volunteers by phase-contrast MR (PC-MR).MethodsA total of 40 iNPH patients and 41 elderly acquired hydrocephalus patients and 26 age-matched healthy volunteers in the normal control (NC) group were included between November 2017 and October 2019 in this retrospective study. The following CSF flow parameters were measured with PC-MR: peak velocity, average velocity (AV), aqueductal stroke volume (ASV), net ASV, and net flow. The following ventricular volume parameters were measured: ventricular volume (VV), brain volume, total intracranial volume, and relative VV. Differences between the iNPH and acquired hydrocephalus groups were compared Mann–Whitney U test and correlations between CSF flow and ventricular volume parameters were assessed using the Spearman correlation coefficient.ResultsAqueductal stroke volume was significantly higher in the iNPH and acquired hydrocephalus groups than in the NC group, but did not differ significantly between the iNPH group and acquired hydrocephalus group. The AV, net ASV, and net flow in the iNPH and acquired hydrocephalus groups were significantly higher than those in the NC group (P < 0.0001), and those in the acquired hydrocephalus group were significantly higher than those in the iNPH group (P = 0.01, P = 0.007, P = 0.002, respectively). The direction of the AV and net ASV significantly differed among the three groups. There were no associations between the volume parameters and CSF flow according to PC-MR among the three groups.ConclusionCompared with iNPH, elderly acquired hydrocephalus demonstrated higher CSF hyperdynamic flow. Although increased CSF flow may contribute to further changes in ventricular morphology, there is no linear relationship between them. These findings might help increase our understanding of flow dynamics in iNPH and elderly acquired hydrocephalus.

Discriminative role of brachial artery Doppler parameters in correlation with hemodialysis arteriovenous fistula.

PurposeThe aim of this study was to evaluate the flow volume and resistive index parameters of the brachial artery in the functioning and dysfunctioning radiocephalic and brachiocephalic hemodialysis arteriovenous fistula (AVF).Methods82 patients were distributed into three groups according to their hemodialysis function - as normal function, decreased pump flow and increased venous pressure. Flow volumes and resistive indexes (RI) of the brachial artery of radiocephalic and brachiocephalic AVFs were measured by Doppler ultrasound. Flow parameters of the groups were compared.ResultsA statistically significant difference was found between the normal and decreased pump flow groups in terms of flow volume and resistive index values. 770 ml/min flow volume of the brachial artery has a 94% sensitivity and 84% specificity and 0.52 value of RI has an 89% sensitivity and 88% specificity in the the differentiation of normal and decreased pump flow groups.ConclusionDoppler parameters of the brachial artery such as flow volume and RI can provide valuable information about AVF function.

Abstract 1496: Quantification of tumor blood perfusion of an orthotopic mouse model of neuroblastoma using nonlinear contrast-enhanced ultrasound imaging

Abstract This study quantifies tumor perfusion in individual tumors to estimate blood flow and blood volume parameters of an individualized tumor compartment of a comprehensive physiologically-based pharmacokinetic model of topotecan using an orthotopic xenograft model of pediatric neuroblastoma. We non-invasively imaged perfusion in orthotopic neuroblastoma (NB5) xenograft tumors (n = 3 CD1 nude mice/time point) using nonlinear contrast enhanced ultrasound technique (CEUS). Tumor tissue and organs from the mice were harvested at predefined time-points. We used a programmable syringe pump to inject MicroMarker® microbubbles via tail vein catheter and acquired images using VisualSonics VEVO 2100 imaging system. We used the burst-replenishment technique to image tumor perfusion, which requires a constant concentration of microbubbles in blood during acquisition. To maintain a steady concentration of microbubbles, we programmed the pump to inject a small bolus followed by constant infusion. Our preliminary analysis showed that healthy kidneys rapidly reach a steady state in less than 1 min, significantly shorter than the commonly used constant infusion without an initial bolus. The nonlinear CEUS signal intensities of kidney cortex showed less than 20% variation between mice. We used a custom program to acquire the CEUS perfusion images over a 3D volume that included the tumor and a kidney. We used the kidney as a reference organ to normalize whole tumor perfusion data. We fitted the log-normal perfusion model to estimate perfusion parameters for individual tumors. Our perfusion quantification over the entire tumor volume represents tumor perfusion more accurately than the commonly used methods based on a single 2D plane without a reference organ. Our approach provides population estimates of blood perfusion based on properly normalized estimates of individual blood perfusion parameters. Citation Format: Suresh Thiagarajan, Abbas Shirinifard, Megan O. Jacus, Abigail D. Davis, Yogesh T. Patel, Stacy L. Throm, Vinay Daryani, Clinton F. Stewart, András Sablauer. Quantification of tumor blood perfusion of an orthotopic mouse model of neuroblastoma using nonlinear contrast-enhanced ultrasound imaging. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1496. doi:10.1158/1538-7445.AM2015-1496

Closing volume and flow volume abnormalities in alpha(1)-antitrypsin phenotype groups in a community population.

Alpha1-antitrypsin phenotype groups, found in a community population studied in Tucson, were compared by using the maximum expiratory flow volume curve and the single-breath nitrogen test, alone and in combination. Subjects 25 to 54 years of age were used for the comparison, among whom there were 728 Pi M, 29 Pi MZ, and 62 Pi MS phenotypes. None of the flow volume parameters or closing volume parameters was able to differentiate among the phenotype groups; subjects in groups heterozygous for alpha1-antitrypsin did not differ from individuals homozygous for Pi M with regard to any or all flow volume or closing volume parameters.

Childhood lung function and the association with β2‐adrenergic receptor haplotypes

To determine associations between ADRB2 polymorphisms and lung function through childhood, and possible modification by gender, pet keeping or tobacco smoke. Four ADRB2 single nucleotide polymorphisms (rs1042711, rs1042713, rs1042714 and rs1800888) were genotyped in 953 children from the prospective birth cohort 'Environment and Childhood Asthma' study and analysed for association with flow-volume parameters at birth (tidal breathing) and at 10 years of age (maximally forced), stratified by environmental exposures. The risk of reduced lung function was reduced in 10-year-old children carrying the most common ADRB2 haplotype (CGGC) (OR 0.45 (95% CI 0.25, 0.82)), whereas there was no association between lung function at birth and ADRB2 haplotypes. Tobacco smoke exposure, gender and pet keeping did not significantly interact with the haplotypes in influencing lung function. This study demonstrates a possible protective effect by the ADRB2 haplotype I (CGGC) on reduced FEV1 in 10-year-old children, whereas no ADRB2 geno-/haplotypes were significantly associated with neonatal lung function. The ADRB2 gene thus appears to contribute to lung function development in childhood, independently of smoking, pets and gender.

Flow-Volume Parameters in COPD Related to Extended Measurements of Lung Volume, Diffusion, and Resistance.

Classification of COPD into different GOLD stages is based on forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) but has shown to be of limited value. The aim of the study was to relate spirometry values to more advanced measures of lung function in COPD patients compared to healthy smokers. The lung function of 65 COPD patients and 34 healthy smokers was investigated using flow-volume spirometry, body plethysmography, single breath helium dilution with CO-diffusion, and impulse oscillometry. All lung function parameters, measured by body plethysmography, CO-diffusion, and impulse oscillometry, were increasingly affected through increasing GOLD stage but did not correlate with FEV1 within any GOLD stage. In contrast, they correlated fairly well with FVC%p, FEV1/FVC, and inspiratory capacity. Residual volume (RV) measured by body plethysmography increased through GOLD stages, while RV measured by helium dilution decreased. The difference between these RV provided valuable additional information and correlated with most other lung function parameters measured by body plethysmography and CO-diffusion. Airway resistance measured by body plethysmography and impulse oscillometry correlated within COPD stages. Different lung function parameters are of importance in COPD, and a thorough patient characterization is important to understand the disease.

SU‐FF‐I‐07: The Effects of Temporal Sub‐Sampling On Estimates of CT Perfusion Parameters in Abdominal Tissues

Purpose: To assess the effects of temporal sampling interval (SI) on estimates of blood flow (BF) and blood volume (BV) parameters derived from CT perfusion (CTP) in abdominal tissues. Method and Materials: CTP data was acquired in ten patients with liver tumors on a 64 row CT (8×5mm thickness, 30s end‐inspiration breathold cine acquisition, 50cc intravenous contrast). For each dataset, the original series (0.5s SI) was reformatted to SIs of 1.0, 2.0 and 3.0s. BF and BV parametric maps for the original and three reformatted series' were computed using commercially available CT perfusion software (CT Perfusion 4, General Electric Healthcare). For each dataset, tumor, normal liver, spleen and kidney regions of interest (ROI's) were defined on a slice‐by‐slice basis on the original 0.5s SI series. For each ROI and each reformatted series, BF and BV values were recorded and plotted against 0.5s SI values for that ROI. Linear regression slope coefficients and R2 values were was used to compute the correlation and fit. Results: In total, 228 ROI were analyzed (108 tumor; 46 normal liver; 53 spleen; 21 kidney). BF showed relatively stable behavior as SI was increased from 0.5s to 3s, with slope coefficients close to unity, in the range 0.974 to 1.022, and with R2 values in the range 0.982 to 0.997. BV showed similar behavior with slope coefficients in the range 0.973 to 1.013, and R2 values in the range 0.972 to 0.976. Conclusion: SI as large as 3s permits relatively accurate estimates of BV and BF in abdominal tissue compared to those obtained with 0.5s intervals. By increasing the SI in such studies, the dose delivered in a liver CTP protocol can be reduced. Conflict of Interest: Research sponsored by GE Healthcare.

Different respiratory phenotypes are associated with isocyanate exposure in spray painters

Associations have been observed between exposure to isocyanates, consisting mainly of oligomers, and respiratory symptoms and isocyanate specific sensitisation in spray painters. The aim of the present study was to assess associations between isocyanate exposure and more objective respiratory effect measures such as bronchial hyperresponsiveness (BHR), baseline spirometry and exhaled nitric oxide (eNO) in a subset of spray painters. Methacholine challenge and eNO measurements were performed in 229 workers. Questionnaires and blood samples were obtained. Specific immunoglobulin (Ig)E and IgG to hexamethylene di-isocyanate were assessed in serum using various assays. Personal exposure was estimated by combining personal task-based inhalatory exposure measurements and time-activity information. Workers with higher isocyanate exposure were more often hyperresponsive (prevalence ratio comparing the 75th versus 25th percentile of exposure 1.8). In addition, significant exposure-related decreased forced expiratory volume in one second (FEV(1)), FEV(1)/forced vital capacity ratio and flow-volume parameters independent of BHR were found. BHR was more prevalent among sensitised workers. This was statistically significant for only IgG-ImmunoCAP (Phadia, Uppsala, Sweden) positive workers. eNO was not associated with exposure although slightly elevated eNO levels in specific IgG positive subjects were found. The current study provides evidence that exposure to isocyanate oligomers is related to asthma with bronchial hyperresponsiveness as a hallmark, but also shows independent chronic obstructive respiratory effects resulting from isocyanate exposure.

To the informative value of flow-volume curve in forced expiration

This report introduces a mathematical model of forced expiration to analyze pulmonary function. Results of 3-year lung function monitoring of an ex-smoker have been shown in the paper. Actual values of lung volumes and airway resistance were used for modeling. The computerized data were compared to the flow-volume curve parameters and lung volumes measured during the forced expiration. Weak correlation between the "flow-volume" curve parameters and the time after quitting smoking together with significant change in the lung volumes and the airway resistance seen in the study could be due to some processes which have not been followed in this study (lung compliance, airway resistance at forced expiration, and elastic properties of airway walls).The results demonstrated that mathematical models could increase informative value of pulmonary functional tests. In addition, the model could emphasize additional functional tests for better diagnostic usefulness of functional investigations.

Toward a Further Elucidation: Role of Vertebral Artery Hypoplasia in Migraine with Aura

A higher frequency of hypoplasic vertebral artery (VA) in patients with migraine with aura than in normal controls has been documented. However, the role of a hypoplasic VA in a migraine attack remains unclear. The aim of our work was to measure the net VA flow volume and related spectral parameters in patients with migraine with aura and a hypoplasic VA. From January 2005 to October 2005 we reviewed the records of 250 migraine outpatients (108 men and 142 women; mean age = 30.8 ± 14.0 years, range = 25–55). Ninety-two patients with migraine with aura were selected. Among these patients, 26 had a hypoplasic VA that was delineated by cervical magnetic resonance angiography. We performed a case-control study that included these 26 migrainous patients. Duplex color-coded ultrasonography was utilized to calculate the spectral parameters during attacks and headache-free periods. The net VA flow volume did not decrease during attacks. A reduction in the resistance index of the hypoplasic VA was noted during attacks in subjects who had migraine with aura. Our observation of VA vasomotor alteration during migraine attacks extends the understanding of the role of a hypoplasic VA. Vasomotor regulation of the VA could be neurogenic in origin. We hypothesize that VA hypoplasia contributes to migraine through complex neurovascular pathways rather than through its low flow volume.

Early detection of cystic fibrosis lung disease: multiple-breath washout versus raised volume tests

Lung clearance index (LCI), a measure of ventilation inhomogeneity derived from the multiple-breath inert gas washout (MBW) technique, has been shown to detect abnormal lung function more readily than spirometry in preschool children with cystic fibrosis, but whether this holds true during infancy is unknown. To compare the extent to which parameters derived from the MBW and the raised lung volume rapid thoraco-abdominal compression (RVRTC) techniques identify diminished airway function in infants with cystic fibrosis when compared with healthy controls. Measurements were performed during quiet sleep, with the tidal breathing MBW technique being performed before the forced expiratory manoeuvres. Measurements were obtained in 39 infants with cystic fibrosis (mean (SD) age 41.4 (22.0) weeks) and 21 controls (37.0 (15.1) weeks). Infants with cystic fibrosis had a significantly higher respiratory rate (38 (10) vs 32 (5) bpm) and LCI (8.4 (1.5) vs 7.2 (0.3)), and significantly lower values for all forced expiratory flow-volume parameters compared with controls. Girls with cystic fibrosis had significantly lower forced expiratory volume (FEV(0.5) and FEF(25-75 )) than boys (mean (95% CI girls-boys): -1.2 (-2.1 to -0.3) for FEV(0.5) Z score; FEF(25-75): -1.2 (-2.2 to -0.15)). When using both the MBW and RVRTC techniques, abnormalities were detected in 72% of the infants with cystic fibrosis, with abnormalities detected in 41% using both techniques and a further 15% by each of the two tests performed. These findings support the view that inflammatory and/or structural changes in the airways of children with cystic fibrosis start early in life, and have important implications regarding early detection and interventions. Monitoring of early lung disease and functional status in infants and young children with cystic fibrosis may be enhanced by using both MBW and the RVRTC.

Applicability of interrupter resistance measurements using the MicroRint ® in daily practice

This study was performed to evaluate the applicability of a simple device (MicroRint ®) for measuring airway resistance, to derive normal values and to compare values with maximal expiratory flow volume (MEFV) parameters in asthmatic and healthy children. Repetitive R int measurements were performed in 125 healthy children and 107 asthmatic children (age range 0.8–16.8 years). In 42 asthmatic patients R int and MEFV values were compared and in 29 asthmatic children bronch-odilation testing was performed. Successful R int measurements were possible in 91% of the children. The mean coefficient of variation of repeated measurements was 7.1(±6.1)%. R int values of healthy children showed a significant curvilinear correlation with age ( r=−0.80, P<0.001) and height ( r=−0.81, P<0.001). In asthmatic and healthy children R int values were comparable. A significant inverse correlation was found between R int and MEFV values (for FEV 1 and R int r=−0.80, P <0.001). After bronchodilation there was a significant increase in FEV 1 and decrease in R int , but changes between the two parameters did not correlate. In conclusion, the interrupter technique is feasible and repeatable in children and has a significant correlation with other parameters of airway caliber. Baseline values do not discriminate healthy from asthmatic children.

Accuracy analysis of a respirometer for activated sludge dynamic modelling

The aim of the paper is to assess the experimental errors arising from the operation of a closed respirometer using autotrophic biomass. A closed, intermittent-flow device has been set-up for the measurement of oxygen uptake rate (OUR) and parameter calibration. After describing the device structure and operation, the factors affecting accuracy have been assessed. Inaccuracies may be caused by two groups of parameters: design parameters, including flow rate, volume, sampling time, numerical algorithm, sample injection and environmental parameters, concerning the physico-chemical conditions of the experiment, such as unwanted oxygen transfer, pH, and the influence of sludge condition on “start-up” behaviour. It is shown to what extent each of them affects the final accuracy of the OUR measurement. In the second part of the paper, the respirometric data are used to calibrate a two-step nitrification model and their impact on the accuracy of the estimation of model parameters is assessed. Confidence limits are derived for the identifiable parameter combinations and the practical identifiability assessed with the aid of trajectory sensitivity analysis.

Tidal breathing analysis as a measure of airway obstruction in children three years of age and older.

This study was designed to evaluate the value and applicability of tidal breathing pattern analysis to assess airflow obstruction in young children. The time needed to reach maximal tidal expiratory flow (TME) divided by total expiratory time (TE) was measured in 228 healthy children 3 to 11 yr of age, 64 patients with asthma, and 12 children with cystic fibrosis. In 70 patients both TME/TE and forced maximal expiratory flow volume (MEFV) parameters were measured. The mean TME/TE in healthy subjects was 43.0 +/- 7.6%. The within-subject reproducibility was high (repeatability index, 5.3%). In the asthmatic patients the mean TME/TE was significantly lower (30.0 +/- 8.2%, p < 0.001), and it increased to 36.5 +/- 7.9% after bronchodilation (n = 44, p < 0.001). The TME/TE level of the subgroup of patients with asthma and FEV1/FVC > or = 0.80 was lower when compared with age-matched normal subjects (30.9 +/- 8.5, p < 0.0001), but it was in a higher range when compared with asthmatics with FEV1/FVC < 0.80 (25.9 +/- 7.9, p < 0.001). In the cystic fibrosis group the mean TME/TE was 27.4 +/- 10.7% without a significant change after bronchodilation. TME/TE correlated significantly with MEFV parameters. Tidal breathing analysis proved easy to perform in children older than 3 yr of age. The TME/TE ratio may be a reliable and simple indicator for airway obstruction.

Respiratory effects and serum type III procollagen in potato sorters exposed to diatomaceous earth.

Exposure to diatomaceous earth with low crystalline silica content (< 1%) is rarely reported to cause pneumoconiotic disease, whereas airway obstruction and bronchitis are more frequently reported. We investigated the occurrence of pneumoconiosis and airflow limitation in 172 male workers from 5 potato sorting plants (55 controls, 29 salesmen, 72 currently exposed, and 16 retired exposed) exposed to inorganic dust from former sea terraces (7.7-15.4 mg/m3), high in diatomaceous earth. The presence of fibrosis was evaluated by chest radiographs (exposed only) and serum levels of type III procollagen (P-III-P) were measured as an estimate of fibrogenetic activity. Lung function was assessed by flow volume curves and impedance measurements. A validated questionnaire was used to record respiratory symptoms. No pneumoconiotic abnormalities were demonstrated by chest radiographs. In line with this finding, serum P-III-P levels were not elevated in exposed workers as compared to controls, suggesting no differences in fibrogenetic activity. In fact, serum P-III-P levels decreased significantly (P < 0.03) with increasing cumulative exposure. Flow volume parameters indicated airflow obstruction, dose-related to (cumulative) dust exposure; the annual decline in forced expiratory flow volume (FEV1) was estimated at 10.5 ml/year (P < 0.05). Airway obstruction was confirmed by impedance analysis: In the retired group impedance changes were compatible with airway obstruction extending into the peripheral airways. We conclude that this exposure to quartz during potato sorting does not result in an increased risk for pneumoconiosis, but that (prolonged) surveillance in this group is desirable in order to detect early indications of airflow obstruction.

Respiratory Symptoms and Lung Function in Animal Feed Workers

In a study among 194 male workers exposed to endotoxin-containing organic dust in animal feed mills, lung function was measured by flow volume curves and impedance measurements and respiratory symptoms were recorded by means of a validated questionnaire. The aims were to detect and localize airway obstruction caused by fodder dust and endotoxin, and to relate respiratory symptoms to both types of lung function measurements. Flow volume and impedance parameters were significantly related to present exposure. All impedance parameters, of the spirometric measures only FEF25, were significantly related to cumulative dust or endotoxin exposure. The changes in impedance parameters were for overall increasing resistance at 8 Hz and decreasing reactance at 8 Hz, reflecting an increase in peripheral airflow obstruction, with increasing exposure. The changes in all lung function parameters were more strongly related to (cumulative) endotoxin exposure than to inspirable dust exposure. All impedance parameters and FEV1 showed a good correlation with complaints of chronic bronchitis and breathlessness. Impedance measurement of the respiratory system proved to be a useful tool for objectively assessing (early) airflow obstruction in workers exposed to inspirable dust and endotoxin and in localizing airflow obstruction.