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Results for “Repeatability and Reproducibility”

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PubMed2004

Measurement of portal blood and transjugular intrahepatic portosystemic shunt flow with use of a retrograde thermodilutional catheter.

PURPOSE: Direct blood flow measurement in the portal vein (PV) and in transjugular intrahepatic portosystemic shunts (TIPS) holds potential as a means of optimizing shunt creation and predicting outcomes. A retrograde thermodilutional flow measurement catheter was recently designed. The purpose of this study was to validate and optimize the technique of blood flow measurement in the PV with use of this catheter in a swine model of TIPS. MATERIALS AND METHODS: Six domestic swine underwent TIPS creation. At day 14, shunts were catheterized for venography and portal blood flow measurement with use of thermodilutional catheters. Simultaneous flow measurements were made with use of the thermodilutional and perivascular methods at the same anatomic location within the PV. To test reproducibility of the flow measurement, repeated measurements were performed in the PV and shunt. RESULTS: Fifty-five measurements of PV blood flow with the thermodilutional catheter and perivascular probe were made in five animals. Perivascular probe placement was unsuccessful in one animal. There was high correlation between the thermodilutional and perivascular measurements (r(2) = 0.96; Q(periv) = 0.80 . Q(therm) + 147 mL/min; n = 55; range, 205-1541 mL/min). The difference between two consecutive thermodilutional measurements and their mean was less than 50 mL/min in 72% of measurements and less than 100 mL/min in 94% of measurements (N = 85 pairs). CONCLUSIONS: Measurement of PV blood flow with use of a retrograde thermodilutional catheter system yields reliable and reproducible results. This catheter system holds promising utility as a device for measuring flow within TIPS and the PV.

Animals↗

PubMed1999

Kinase Receptor Activation (KIRA): a rapid and accurate alternative to endpoint bioassays.

We have developed a novel strategy for a rapid bioassay that is accurate, precise, sensitive, and high capacity. It is capable of quantifying ligand bioactivity by measuring ligand-induced receptor tyrosine kinase activation in terms of receptor-phosphorylation. The assay, termed << Kinase Receptor Activation>> or KIRA, uses two separate microtiter plates, one for ligand stimulation of intact cells, and the other for receptor capture and phosphotyrosine ELISA. The assay makes use of either endogenously expressed receptors or stably transfected receptors with a polypeptide flag. KIRA assays for the ligands IGF-I and NGF were compared to their corresponding endpoint bioassays (3T3 cell proliferation for IGF-I and PC12 cell survival for NGF). The KIRA assays showed excellent correlation with the more classical endpoint bioassays. Further, they were highly reproducible, minimizing the requirement for repeat assays. The KIRA assay format has great potential as a rapid, accurate and precise bioassay, both for potency determination as well as stability-indicating analyses.

3T3 Cells↗

PubMed1999

Comparison of recording systems and analysis methods in specular microscopy.

PURPOSE: To compare corneal endothelial cell images from contact and automated noncontact specular microscopes and to compare endothelial image analysis by the Konan Robo Center Method and the Bio Optics Bambi Corners Method. METHODS: Twenty-six normal corneas of 13 subjects and 41 penetrating keratoplasties (PKs) of 38 patients were photographed with a Keeler-Konan contact specular microscope and a Konan Noncon Robo automated noncontact specular microscope. (i) After measuring and calibrating the magnification of each instrument, we digitized the cellular apices and analyzed the images from both instruments by using the Corners Method modified to accept x and y calibrations. (ii) Using the internal calibration marks of the Konan Noncon Robo specular microscope for calibration of magnification (as required for the Center Method), we evaluated identical cells on images from this microscope by both the Center Method and the Corners Method. (iii) We evaluated the reproducibility of both methods by repeating measurements on the same image. RESULTS: (i) When the images were properly calibrated for magnification by using an external scale, endothelial cell density (ECD) of normal corneas was 2,703 +/- 354 (mean +/- SD) cells/mm2 by contact and 2,685 +/- 357 cells/mm2 by noncontact techniques (p = 0.51). ECD of PK corneas was 1,767 +/- 773 cells/mm2 by contact and 1,807 +/- 775 cells/mm2 by noncontact techniques (p = 0.31). (ii) When images from the Konan Noncon Robo specular microscope were calibrated for magnification on the internal marks, the measured ECD from the same noncontact photographs was 6% less (p < 0.001). ECD was then 2,519 +/- 294 cells/mm2 (means +/- SD) by the Center Method and 2,523 +/- 305 cells/mm2 by the Corners Method (p = 0.55) in normal corneas and 1,715 +/- 748 cells/mm2 by the Center Method and 1,731 +/- 763 cells/mm2 by the Corners Method (p = 0.04) in PK corneas. (iii) The coefficient of variation of repeated measurements on the same normal image was 0.0025 for the Centers Method and 0.0099 for the Corners Method. CONCLUSIONS: (i) Images from the automated noncontact specular microscope may be used interchangeably with those from the contact specular microscope to measure ECD, but only if both are properly calibrated by measuring an external scale. (ii) As a method of analysis, the Center Method is equivalent to the Corners Method in normal corneas, but the proprietary internal calibration of the Center Method, which is required for its use, yields ECDs approximately 6% less than when an external scale is used for distance calibration. (iii) Cell density measurements by both the Center Method and the Corners Method were reproducible within 1%.

Cell Count↗

PubMed2005

Teaching more by lecturing less.

We carried out an experiment to determine whether student learning gains in a large, traditionally taught, upper-division lecture course in developmental biology could be increased by partially changing to a more interactive classroom format. In two successive semesters, we presented the same course syllabus using different teaching styles: in fall 2003, the traditional lecture format; and in spring 2004, decreased lecturing and addition of student participation and cooperative problem solving during class time, including frequent in-class assessment of understanding. We used performance on pretests and posttests, and on homework problems to estimate and compare student learning gains between the two semesters. Our results indicated significantly higher learning gains and better conceptual understanding in the more interactive course. To assess reproducibility of these effects, we repeated the interactive course in spring 2005 with similar results. Our findings parallel results of similar teaching-style comparisons made in other disciplines. On the basis of this evidence, we propose a general model for teaching large biology courses that incorporates interactive engagement and cooperative work in place of some lecturing, while retaining course content by demanding greater student responsibility for learning outside of class.

Attitude↗

PubMed1982

Long-term storage and regular repeated use of diluted antisera in glass staining jars for increased sensitivity, reproducibility, and convenience of single- and two-color light microscopic immunocytochemistry.

A procedure is described for the dilution and storage of antisera in glass staining jars into which whole slides are immersed for incubation during light microscopic neuropeptide immunocytochemistry. Diluted antisera, stored at 4 degrees C and continuously reused, were found to be stable for long periods of time (to date over 3 years), and consistently yielded high quality staining in both single- and two-color immunoperoxidase staining. We found this procedure to be more convenient than conventional incubation procedures, allowing the more rapid processing of large numbers of slides and reducing the loss of slides due to technical errors. The consistency and reproducibility of day to day staining were also improved. The immersion of whole slides into the antisera permitted the use of long incubation times (up to 7 days) without the sections drying out, which in many cases substantially enhanced the sensitivity of the staining obtained. A procedure for two-color immunoperoxidase staining is described using diaminobenzidine for a brown color and alpha-naphthol/pyronin for a red/purple color. We found the alpha-naphthol/pyronin reaction superior to the more commonly used 4-chlornaphthol reaction as a second color. The two-color staining was found useful not only for demonstrating nerve cell bodies stained different colors, but also for staining nerve terminals one color that are around and contacting nerve cell bodies stained another color.

Adrenocorticotropic Hormone↗

PubMed1993

Reproducibility of ambulatory intragastric pH monitoring.

Ambulatory 24-hour intragastric pH monitoring is nowadays the standard technique for assessing intragastric acidity. For (patho)physiological and pharmacological studies the method has to be sensitive and reproducible. Intragastric acidity was measured continuously by means of intragastric electrodes in the gastric corpus. In order to assess the reproducibility of the test, we repeated it test twice on separate days under standardized conditions in 8 healthy subjects. Subjects were fully ambulatory and no medication was administered. We found no significant difference between 24-hour median pH values during both study days [1.45 (range 1.20-1.90) and 1.40 (1.20-2.00), day 1 and 2, respectively]. There was a significant overall correlation between consecutive 30-min median pH values during 24 hours (r = 0.97, p < 0.0001). Over 24 hours and during the day the technique was able to detect consistent pH changes of > 0.1 pH units, but during the night only changes of > 0.3 pH units could be detected, due to nocturnal pH fluctuations in two subjects. This study shows that ambulatory 24-hour intragastric pH monitoring is reproducible and is able to detect small changes in gastric acidity.

Adult↗

PubMed1994

Evaluation of left ventricular asynchrony by radionuclide angiography: comparison of phase and sector analysis.

UNLABELLED: The aim of this study was to assess the optimal method to evaluate asynchrony in equilibrium radionuclide angiography (RNA). METHODS: We studied 20 patients (14 males and 6 females, age range 25-60 yr) with RNA during atrial and sequential atrioventricular (AV) pacing, which increased left ventricular (LV) asynchrony. Both studies were performed at the same heart rate. Asynchrony was assessed either on phase images, by computing the standard deviation of the phase distribution (SD-P) and by sector analysis. Systolic and diastolic asynchrony were evaluated as the coefficient of variation of time to end systole (CV-TES) and time to peak filling rate (CV-TPFR) in four sectors. In addition, phase values were computed on time-activity curves from the same sectors, and their standard deviation (SD-Psec) was computed. RESULTS: During atrial pacing SD-P was 32.3 degrees +/- 6.7 degrees and did not change during AV pacing (32.1 degrees +/- 5.6 degrees, p = n.s.). Both CV-TES and CV-TPFR had a significant increase during AV pacing (from 7.7% +/- 3.9% to 11.5% +/- 6.4%, p < 0.01, and from 8.4 degrees +/- 5.8 degrees to 12.9 degrees +/- 6.7 degrees, p < 0.001). AV pacing led to a significant increase in SD-Psec (from 6.3 degrees +/- 4.0 degrees to 12.6 degrees +/- 9.7 degrees, p < 0.05). Moreover, reproducibility was assessed in 15 additional age-matched patients. The results of the reproducibility study indicate a better repeatability for CV-TES and CV-TPFR. CONCLUSIONS: The findings of this study suggest that sector analysis with calculation of indices of LV systolic and diastolic asynchrony is better suited for quantitation of LV temporal nonuniformity.

Cardiac Catheterization↗

PubMed2001

The quantification of dental plaque using an image analysis system: reliability and validation.

AIM: Established clinical indices used to measure dental plaque have limitations. The aim of this study was to develop and evaluate a new method of quantitative plaque measurement, with increased sensitivity and reproducibility, using a purpose designed image analysis system. METHOD: After plaque disclosure, the patient was positioned in a cephalometric head holder mounted in a custom-built frame with standard lighting and camera position. A 32-bit Digital Camera grabbed the image of the patient's teeth, which was analysed using Adobe Photoshop (V5.02, Adobe Systems Ltd, Europe) and Image Pro Plus software (V4.0, Media Cybernetics, USA). Measurements were made on 120 incisors in 15 patients and reproducibility was assessed using Fliess' Coefficient of Reliability. Sensitivity was assessed by comparison of results of treatment effects from a clinical trial involving 30 patients. Analysis of covariance was used to compare the image analysis system with the Turesky modification of the Quigley and Hein plaque index and the Addy plaque area index. RESULTS: The results were within the 'Excellent Reliability' category, for inter-operator reproducibility and intra-operator repeatability. CONCLUSIONS: This new system provided accurate quantitative measurements of dental plaque and labial tooth surfaces and was shown to have increased sensitivity when compared with the Turesky modification of the Quigley and Hein plaque index and the Addy plaque area index. The stored images can be re-measured for reliability and comparability between studies.

Analysis of Variance↗

PubMed1996

[Reproducibility of contrast sensitivity test results].

Two methods (a double staircase and an adjustment method) for repeated measuring of the contrast sensitivity in inexperienced observers (e.g. in patients undergoing the photorefractive keratectomy) were compared in 10 subjects. Using the coefficient of repeatability of Bland and Altmann it could be shown that the reproducibility is better in the method of adjustment. The coefficient of repeatability of this method amounted for 95% confidence limits to 4.78 dB, whereas in the method of double staircase it was 8.70 dB.

Adult↗

PubMed1988

[Reproducibility of the quantitative indices of the global and regional function of the left ventricle when determined repeatedly by the same researcher].

10 healthy persons were examined by two left ventriculographies--conventional and hemiaxial. The results show good and exceptionally good reproducibility (r = 0.80 up to 0.90) of the quantitative indices for global left ventricular function in all projections with the exception of the end systolic volume index of the left ventricule in the cranial left anterior oblique projection (r = 0.67) and of the ejection fraction in the left oblique projections (r = 0.6 and 0.68). The results of the segmental analysis of the left ventricular wall movements show good reproducibility in the four projections (p greater than 0.1) in spite of the fact that the models used depend on the exact determination of the cardiac apex.

Adult↗

PubMed2005

Diagnostic tools in pseudohypacusis in children.

Pseudohypacusis is the term used for a non-organic or functional hearing loss. The mainstay of diagnosis is a lack of consistency in audiological testing. It is usually easier to diagnose in children than in adults, as children are less able to reproduce consistently erroneous results on repeated testing. Nevertheless, the diagnosis is often missed in children, probably due to a lack of awareness of the condition. In a previous study from our department, we highlighted the usefulness of speech audiometry in establishing the diagnosis. However, with the advent of otoacoustic emissions testing, we have changed the emphasis of our testing protocol. Using otoacoustic emissions, the diagnosis of pseudohypacusis can be established quickly and easily.

Adolescent↗

PubMed1996

The effects of long-term prone positioning in patients with trauma-induced adult respiratory distress syndrome.

Prone positioning improves gas exchange in some patients with adult respiratory distress syndrome (ARDS), but the effects of repeated, long-term prone positioning (20 h duration) have never been evaluated systemically. We therefore investigated 20 patients with ARDS after multiple trauma (Injury Severity Score [ISS] 27.3 +/- 10, ARDS score 2.84 +/- 0.42). Patients who fulfilled the entry criteria (bilateral diffuse infiltrates, severe hypoxemia, pulmonary artery occlusion pressure [PAOP] < 18 mm Hg, and PaO2/fraction of inspired oxygen [FIO2] < 200 mm Hg at inverse ratio ventilation with positive end-expiratory pressure [PEEP] > 8 mm Hg for more than 24 h) were turned to the prone position at noon and were turned back to the supine position at 8:00 AM on the next day. Thus only two turns per day were necessary, and the risk of disconnecting airways or medical lines was minimized. Prone positioning was repeated for another 20 h if the patients fulfilled the entry criteria. Except for FIO2, the ventilator settings remained unchanged during the study period. All patients were sedated and, if needed paralyzed to minimize patient discomfort. One hour before and after each position change, ventilator settings and pulmonary and systemic hemodynamics were recorded and blood was obtained for blood gas analysis. Derived cardiopulmonary and ventilatory variables were calculated using standard formulas. Overall mortality was 10%. Oxygenation variables improved significantly each time the patients were placed prone. Immediately after the first turn from the supine to the prone position the following changes were observed: PaO2 increased from 97 +/- 4 to 152 +/- 15 mm Hg, intrapulmonary shunt (Qva/Qt) decreased from 30.3 +/- 2.3 to 25.5 +/- 1.8, and the alveolar-arterial oxygen difference decreased from 424 +/- 24 to 339 +/- 25 mm Hg. All these changes were statistically significant. Most of these improvements were lost when the patients were turned supine, but could be reproduced when prone positioning was repeated after a short period (4 h) in the supine position. Short periods in the supine position were necessary to allow for nursing care, medical evaluation, and interventions such as placement of central lines. No position-dependent changes of systemic hemodynamic variables were observed. We conclude that, in trauma patients with ARDS undergoing long-term positioning treatment, lung function improves significantly during prone position compared to short phases of conventional supine position during which the beneficial effects are partly lost.

Adult↗

PubMed1992

Objective quantification of spastic hypertonia: correlation with clinical findings.

To develop a reliable and objective technique for quantifying spastic hypertonia, ten chronically hemiplegic patients with varying degrees of spasticity were studied on three occasions during several weeks. The modified Ashworth scale, a clinical assessment of extremity tone, was performed before and after each of the following objective tests: (1) torque and EMG measurements during ramp and hold angular displacement about the elbow, (2) pendulum test of the lower extremity, and (3) H/M ratio studies of upper and lower extremities. Subject motor function was also quantified using the Fugl-Meyer motor assessment scale. A regression analysis was performed to determine how successfully each of the objective measures correlated with the clinical yardstick, the modified Ashworth scale. A similar correlation between the objective measures and the Fugl-Meyer motor assessment scale was performed. Temporal reproducibility of a test for a given subject was evaluated by performing an ANOVA of repeated measures for each test over the three study sessions in a given subject. We conclude that (1) both the ramp and hold threshold measurements and pendulum test offer acceptable objective measures of spastic hypertonia since they correlate closely with clinical perception, (2) the Fugl-Meyer motor assessment scale also correlates closely with the severity of spastic tone, and (3) objective measures of spastic hypertonia are often surprisingly reproducible when repeatedly applied to a selected group of chronic hemiplegic patients with long-standing spasticity.

Adult↗

PubMed1998

Electro-oophorogram: A preliminary study of the electric activity of the ovary.

The electric activity of the ovary was studied in 13 female mongrel dogs aiming at characterizing a normal electro-oophorogram (EOOG). Two monopolar silver-silver chloride electrodes were sutured under anesthesia to the ovary of the bitches which were in the anestrus phase of the estrous cycle. A daily recording session of 60 min was performed for 10 days. Furthermore, the effect of ovarian vessels' clamping, of oophorectomy and of ovarian insult by irradiation on the electric activity, was studied. Electric waves were recorded from the two electrodes. Each wave consisted of a negative followed by a positive deflection with a mean amplitude of 52.6 +/- 10.7 microV and frequency of 9.2 +/- 1.6 cycles per second. The waves showed the same amplitude and frequency from the two electrodes and were reproducible when the test was repeated in the same animal. Fast activity spikes were not encountered. Temporary clamping of the ovarian vessels caused diminution of the normal ovarian electric activity which returned to the preclamping state after clamp release. A 'silent' EOOG was obtained after oophorectomy. Two EOOG patterns were recorded from the irradiated ovary: silent and dysrhythmic. To conclude, an EOOG could be characterized for the bitches in the anestrus phase which is a quiescent phase of the estrous cycle. Further studies are required to record the EOOG in the other phases of the estrous cycle and in the various pathologic conditions of the ovary.

Anestrus↗

PubMed2001

Off-line exhaled nitric oxide measurements in children.

The concentration of exhaled nitric oxide (eNO) is a useful marker of asthmatic bronchial inflammation. eNO can now be measured away from the laboratory (off-line), even in children. Short exhalation maneuvers (8 sec) and small samples (1 L) of exhaled gas are probably sufficient in children, but more information is needed about the effect of different measurement conditions. As a preliminary step before conducting epidemiological studies in schoolchildren, we investigated the effects of expiratory flow, dead space, and expiratory time on eNO concentrations collected in 1-L mylar collection bags. We studied 101 cooperative subjects (62 males) aged 5-18 years (30 healthy volunteers, 51 asthmatics, and 20 children with various other respiratory diseases) in our pulmonary function laboratory. On-line and off-line eNO were compared in a single session, and analyzed with a Sievers NOA 280 nitric oxide analyzer. For both methods of collecting expired gas, subjects did a single exhalation without breath-holding against an expiratory pressure 10 cm H(2)O. We investigated the effects of expiratory flow, dead space, and exhalation time on eNO; we also compared on-line and off-line eNO measurements, and the repeatability of both techniques at a given flow rate. Expiratory flows of 58 mL/sec provided more reproducible data than lower flows (coefficient of repeatability 1.1 ppb for 58 mL/sec vs. 2.8 for 27 mL/sec vs. 5.7 for 18 mL/sec). eNO concentrations were about 25% higher in off-line than in on-line recordings if the initial 250 mL of exhaled gas were not eliminated, and 37% higher if exhalation lasted longer (16 sec vs. 8 sec). Eliminating 250 mL of dead space and shortening the filling time to 8 sec yielded off-line eNO values close to those on-line (geometric mean off-line eNO 14.4 ppb, 95% confidence interval: 12.2-17.0) vs. on-line eNO 13.8 ppb (95% confidence interval: 11.6-16.5). On-line and off-line results were highly correlated (r = 0.996, P = 0.000) and had similar coefficients of variation (on-line eNO 2.6%, off-line 2.8%). Neither agreement nor repeatability of eNO measurements were affected by disease status or baseline FEV(1) (% predicted values). Once standardized, the off-line eNO technique using 1-L gas collection bags will provide results similar to those recorded on-line.

Adolescent↗

PubMed2005

Reproducibility of forearm vasodilator response to intra-arterial infusion of calcitonin gene-related peptide assessed by venous occlusion plethysmography.

AIMS: To assess the reproducibility of the forearm blood flow (FBF) response to intra-arterial infusion of calcitonin-gene related peptide (CGRP), measured by venous occlusion plethysmography. In addition, to compare different ways of expressing the FBF response and perform sample size calculations. METHODS: On two separate visits, CGRP (10 ng min(-1) dl(-1) forearm) was infused for 45 min into the brachial artery of six healthy subjects. Reproducibility was assessed by calculating mean difference, repeatability coefficient, within-subject coefficient of variation (WCV) and intraclass correlation coefficient. RESULTS: CGRP increased FBF from 2.8 +/- 0.4 and 3.2 +/- 0.7 (at baseline) to 15.4 +/- 1.4 and 15.2 +/- 1.5 ml min(-1) dl(-1) forearm (at 45 min) on visits 1 and 2, respectively (P < 0.0001 for both visits). Mean difference in FBF at 45 min between both visits was 0.3 ml min(-1) dl(-1) forearm (repeatability coefficient: 4.1 ml min(-1) dl(-1) forearm). This FBF response appeared to be more reproducible when expressed as absolute FBF in the infused arm (WCV 11%) compared with absolute FBF-ratio between both arms (WCV 37%), percentage change from baseline in FBF in the infused arm (WCV 29%) and percentage change from baseline in FBF-ratio (WCV 40%). When expressed as absolute FBF, a sample size of five (95% confidence interval: 2-12) subjects gives 90% power at a type I error probability of 0.05 to detect a 25% shift in FBF response. CONCLUSIONS: Intra-arterial infusion of CGRP results in a forearm vasodilator response which is reproducible between days. This response is most reproducible when expressed as absolute FBF. The presented methodology provides a suitable pharmacodynamic model to assess the in vivo activity of CGRP-receptor antagonists in a small number of subjects.

Adult↗

PubMed1995

Short-term evaluation of plaque area measurement reproducibility from computer-assisted sonography.

One reason why quantifying plaque regression is difficult is the poor spatial control of the shooting angle whether in angiography or ultrasonography techniques. A computer-assisted technique has been developed to assess absolute carotid plaque dimensions from B-mode ultrasonography, with enhanced capability of comparative examinations at large time intervals. Plaque area is measured from arterial lumen to adventitia with a real-time tissular detection program. Further measurements on the same patient are made using an echo-specific mask automatically generated by the computer from the original section. For an average sonographer, the manipulation takes no more than ten minutes for each view. In order to determine the reproducibility of this technique, a repeated measurement study (T0, T1, T2) was carried out on 8 patients with moderate to severe atherosclerotic lesions at carotid localizations. The plaque areas ranged from 52.7 to 202.3 mm2 (120.7 +/- 61). The coefficients of correlation between the measurements (T0-T1, T0-T2) were respectively 0.93 and 0.96 (P < 0.0001). The mean coefficient of variation (+/- SD) was 9.8% +/- 4.8. This study shows the feasibility of an accurate follow-up for atherosclerotic patients, with a two-dimensional plaque quantification, closer to the reality of the evolution of the pathology than the usual scoring system.

Aged↗

PubMed2004

Novel method for measuring effects of gas compression on expiratory flow.

During forced vital capacity maneuvers in subjects with expiratory flow limitation, lung volume decreases during expiration both by air flowing out of the lung (i.e., exhaled volume) and by compression of gas within the thorax. As a result, a flow-volume loop generated by using exhaled volume is not representative of the actual flow-volume relationship. We present a novel method to take into account the effects of gas compression on flow and volume in the first second of a forced expiratory maneuver (FEV(1)). In addition to oral and esophageal pressures, we measured flow and volume simultaneously using a volume-displacement plethysmograph and a pneumotachograph in normal subjects and patients with expiratory flow limitation. Expiratory flow vs. plethysmograph volume signals was used to generate a flow-volume loop. Specialized software was developed to estimate FEV(1) corrected for gas compression (NFEV(1)). We measured reproducibility of NFEV(1) in repeated maneuvers within the same session and over a 6-mo interval in patients with chronic obstructive pulmonary disease. Our results demonstrate that NFEV(1) significantly correlated with FEV(1), peak expiratory flow, lung expiratory resistance, and total lung capacity. During intrasession, maneuvers with the highest and lowest FEV(1) showed significant statistical difference in mean FEV(1) (P < 0.005), whereas NFEV(1) from the same maneuvers were not significantly different from each other (P > 0.05). Furthermore, variability of NFEV(1) measurements over 6 mo was <5%. We concluded that our method reliably measures the effect of gas compression on expiratory flow.

Adult↗