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Biomedical subjects

J Sanchis

Publications and source records attributed to J Sanchis.

At least 55 records · Page 3Linked to original sources
PubMed1999

ST-segment elevation on Q leads at rest and during exercise: relation with myocardial viability and left ventricular remodeling within the first 6 months after infarction.

BACKGROUND: Resting ST-segment elevation on Q leads after an acute myocardial infarction has been related to a greater infarct size. Otherwise, the relation between exercise-induced ST-segment elevation and myocardial viability is controversial. We investigated the relation between ST-segment elevation on Q leads at rest and during exercise and regional dysfunction and its evolution, contractile reserve, left ventricular dilation, and coronary patency. METHODS AND RESULTS: Exercise testing and cardiac catheterization were performed at the first week after infarction in 51 patients. The study group was divided according to the existence (in 2 or more Q leads; n = 36) or not (n = 15) of resting ST-segment elevation and according to the existence (n = 28) or not (n = 23) of exercise-induced ST-segment elevation. Left ventricular end-diastolic and end-systolic volumes (mL/m2), regional wall motion (SD/chord), contractile reserve (wall motion percentage improvement with low-dose dobutamine), and coronary patency in the culprit artery were analyzed. Cardiac catheterization was repeated at the sixth month in 35 patients; systolic recovery (wall motion percentage improvement), left ventricular volumes, and coronary patency were again evaluated. Patients with resting ST-segment elevation showed poorer wall motion (2.1 +/- 0.8 SD/chord vs 1.2 +/- 1 SD/chord, P =.002), lesser contractile reserve (17% [0% to 39%] vs 41% [4% to 92%], P =.04), greater end-systolic volume (32 +/- 15 mL/m2 vs 23 +/- 11 mL/m2, P =.04), and higher percentage of occlusion (36% vs 7%, P =.04) than did patients without ST-segment elevation. Likewise, patients with exercise-induced ST-segment elevation showed lesser contractile reserve (8% [0% to 40%] vs 35% [12% to 86%], P =.03) than did patients without exercise-induced ST-segment elevation. The only independent predictors of contractile reserve were wall motion <2 SD/chord (odds ratio [OR] 7.1, confidence interval [CI] 6.3 to 7.9, P =.01) and the absence of exercise-induced ST-segment elevation (OR 5.7, CI 4.9 to 6.5, P =. 02). There were no significant differences between patients with and those without ST-segment elevation (at rest or during exercise) in systolic recovery or left ventricular volumes at the sixth month. CONCLUSIONS: ST-segment elevation on Q leads at rest is related to a poorer systolic function (more severe regional dysfunction, greater end-systolic volume, and less response to dobutamine). ST-segment elevation during exercise is independently related to a lesser contractile reserve. ST-segment elevation (at rest or during exercise) is not related to the evolution of volumes or regional dysfunction during the first 6 months after infarction.

Aged↗
PubMed1999

[Hospital admission for asthma. Descriptive analysis and prognostic factors after discharge].

BACKGROUND: Few authors have looked at admissions in Spain of patients with acute asthma attacks. The aim of this study was to determine the clinical profile of such patients and analyze factors influencing disease course after release. METHODS: Asthmatics admitted to our hospital were enrolled prospectively over 12 consecutive months. The patients were telephoned one and four months after release. Demographic and clinical data were collected in addition to data on exacerbations, readmissions, treatment and medical follow-up. RESULTS: Sixty-five patients (44 women and 21 men, mean age 45, SD 19). Most (54%) were admitted in autumn and the most common cause of exacerbation was respiratory tract infection (68%). Before admission, 54% had severe asthma, 32% had moderate asthma and 14% had mild asthma. At least one exacerbation occurred for 54% of patients, while 38% required emergency assistance and 19% were readmitted. Two patients (3%) died of asthma. Multiple factor logistic regression analysis showed a relation between the appearance of exacerbation after release and greater severity of asthma and the absence of long-lasting (beta-adrenergic drugs. Readmission was related to shorter duration of treatment with oral glucocorticoids after release and a higher number of prior hospital admissions. CONCLUSIONS: 1) Admission due to asthma occurs mainly in autumn and is probably related to respiratory infections, rather than exclusively to severe asthma. 2) After release, short-term morbidity and mortality due to the disease are high. 3) Disease severity itself and inadequate treatment are both related to poor clinical course after release.

Adult↗
PubMed1999

[The activation patterns during atrial fibrillation in an experimental model].

INTRODUCTION AND OBJECTIVES: In atrial fibrillation, along with the mechanisms of complete reentry and random activation focal activation patterns have been described which have been attributed both to propagation from the endocardium and to the existence of zones with automatic activity. The objectives of present study are to analyze and quantify the atrial activation patterns in an experimental model of atrial fibrillation. MATERIAL AND METHODS: In 11 Langendorff-perfused rabbit hearts atrial fibrillation was induced by atrial burst pacing after right atrial dilatation with an intra-atrial balloon. A multiple electrode consisting of 121 electrodes and positioned in the right atrial free wall was used to construct the activation maps corresponding to 10 segments of 100 ms in 11 different episodes of sustained atrial fibrillation (one per experiment). RESULTS: Of the 110 segments analyzed, 44 (40%) corresponded to random activation patterns. Fifteen segments (14%) corresponded to complete reentry, and in these cases the number of consecutive rotations ranged from 1 to 2.25 (mean 1.4 +/- 0.4). In 49 segments (44%) a single activation front was seen to pass through the recording area without block; alternatively, two simultaneous fronts were recorded that did not re-excite the zone activated by the other. In two segments (2%) there was a focal activation pattern without evidence of propagation from the epicardium surrounding the activated zone. CONCLUSIONS: a) in the experimental atrial fibrillation model used, random activation patterns are more frequent than complete reentry patterns; b) complete reentry can occur in areas smaller than 1 cm2, and c) focal activation during atrial fibrillation is rare.

Analysis of Variance↗
PubMed1999

Ventilatory compensation for inspiratory resistive loads during anaesthesia with halothane or isoflurane.

We have analysed the ventilatory response to sustained inspiratory resistive loads in 14 patients, while awake and during halothane (n = 7) or isoflurane (n = 7) anaesthesia. Patients breathed halothane or isoflurane in oxygen at 1.2 minimum alveolar concentration (MAC). Inspiratory resistances of 0, 12 and 37 cm H2O litre-1 s were applied. Tidal volume (VT) was maintained with the greater loads. At the greatest resistance, a significant reduction in minute ventilation occurred in both awake (-18.9%) and anaesthetized states, with both halothane (-10.4%) and isoflurane (-14.5%). Ventilatory frequency decreased significantly from mean 14.6 (SD 4.7) to 12.5 (4.3) bpm in the awake state and during anaesthesia, with increasing inspiratory resistance (29.5 (3.6) to 23.7 (7.2) bpm and 25.8 (3.3) to 23.4 (4.0) bpm, respectively, for halothane and isoflurane) because inspiratory time (TI) was significantly longer (P < 0.01). End-tidal PCO2 increased by 0.3 kPa, on average, from baseline to the highest level of resistance (P < 0.01). Inspiratory occlusion pressure at 100 ms increased significantly with increased loading in all situations (P < 0.001). We found a similar pattern of ventilatory adaptation to sustained inspiratory flow resistive loads both in awake and anaesthetized states. VT was maintained at increased loads because of an increase in inspiratory neuromuscular output and inspiratory duration.

Adolescent↗
PubMed1999

Reduction of atrial fibrillation inducibility by radiofrequency ablation: an experimental study.

UNLABELLED: A study is made of the antifibrillatory effects of radiofrequency (RF)-induced atrial lesions using nine Langendorff-perfused rabbit hearts in which the atrial electrophysiological properties and atrial fibrillation (AF) inducibility were modified by atrial stretching. Using a multiple electrode consisting of 121 unipolar electrodes, determinations were made of the atrial refractory periods, conduction velocity, wavelength of the atrial activation process, and the inducibility of sustained AF episodes (duration over 30 s) by atrial burst pacing in four situations: (a) control; (b) following dilatation of the right atrium; (c) after adding an RF linear lesion at the cava-tricuspid annulus isthmus; and (d) after adding two RF linear lesions rounding the base of the right atrial appendage and extending from the inferior zone of the sulcus terminalis to the anterior wall of the appendage. Under control conditions, AF was not induced in any of the experiments. The wavelengths were 10.5 +/- 1.2 cm for basic cycles of 250 ms and 6.6 +/- 0.5 cm for cycles of 100 ms. Following dilatation, a significant decrease was recorded in the atrial refractory periods, conduction velocity, and wavelength, which reached values of 6.1 +/- 0.7 cm (250-ms cycle, P < 0.01), and 3.9 +/- 0.3 cm (100-ms cycle, P < 0.01); AF was induced in five cases (P < 0.05). After producing the lesion at the cava-tricuspid isthmus, the electrophysiological modifications induced by atrial dilatation persisted (wavelength = 6.2 +/- 0.6 cm (250-ms cycle) and 4.3 +/- 0.3 cm (100-ms cycle); P < 0.01 vs the control) and AF was triggered in eight cases (P < 0.0001). In turn, on adding the two lesions at the right atrial free wall and appendage, AF was induced only in one experiment (P = NS vs control), and the dilatation-induced decrease in refractoriness and wavelength was attenuated. Nevertheless, differences remained significant with respect to the controls, with the exception of the functional refractory periods determined at cycles of 100 ms. In this phase, the wavelength was 6.6 +/- 0.7 cm (250-ms cycle, P < 0.01 vs control) and 4.9 +/- 0.5 cm (100-ms cycle; P < 0.05). Atrial conduction between the zones separated by the lesions was blocked at any frequency, or selectively at rapid atrial activation frequencies. IN CONCLUSION: (a) the production of three linear lesions in the right atrium (cava-tricuspid isthmus, atrial appendage, and inferior free wall) reduces AF inducibility in the experimental model used; (b) conduction block (either absolute or frequency dependent) through the lesions, reduction in tissue mass caused by lesion creation, and possibly the attenuation of the shortening of atrial refractoriness and wavelength in the zones not separated by the lesions are implicated in the reduction of AF inducibility; and (c) the single lesion in the cava-tricuspid isthmus does not impede AF inducibility.

Animals↗
PubMed1999

Expiratory flow limitation during exercise in competition cyclists.

In some trained athletes, maximal exercise ventilation is believed to be constrained by expiratory flow limitation (FL). Using the negative expiratory pressure method, we assessed whether FL was reached during a progressive maximal exercise test in 10 male competition cyclists. The cyclists reached an average maximal O2 consumption of 72 ml. kg-1. min-1 (range: 67-82 ml. kg-1. min-1) and ventilation of 147 l/min (range: 122-180 l/min) (88% of preexercise maximal voluntary ventilation in 15 s). In nine subjects, FL was absent at all levels of exercise (i.e., expiratory flow increased with negative expiratory pressure over the entire tidal volume range). One subject, the oldest in the group, exhibited FL during peak exercise. The group end-expiratory lung volume (EELV) decreased during light-to-moderate exercise by 13% (range: 5-33%) of forced vital capacity but increased as maximal exercise was approached. EELV at peak exercise and at rest were not significantly different. The end-inspiratory lung volume increased progressively throughout the exercise test. The conclusions reached are as follows: 1) most well-trained young cyclists do not reach FL even during maximal exercise, and, hence, mechanical ventilatory constraint does not limit their aerobic exercise capacity, and 2) in absence of FL, EELV decreases initially but increases during heavy exercise.

Adolescent↗
PubMed1998

[Acute changes in wavelength of the process of auricular activation induced by stretching. Experimental study].

OBJECTIVE: An evaluation is made of the acute modifications in the wavelength of the atrial excitation process induced by atrial stretching. MATERIAL AND METHODS: In 10 isolated Langendorff-perfused rabbit hearts and using a multiple electrode the wavelength of the atrial activation process (functional refractory period x conduction velocity) was determined in the right atrium. An analysis was also made of the inducibility of rapid repetitive atrial responses after 20 episodes of atrial burst pacing. Measurements were made under control conditions, after inducing two degrees of atrial wall stretch (D1 and D2), and following the suppression of atrial dilatation. RESULTS: Under control conditions the wavelength was 72.6 +/- 7.7 mm (250 ms cycle) and 54.0 +/- 5.1 mm (100 ms cycle). In D1 (mean longitudinal increase in atrial wall length = 24 +/- 3%) the wavelength shortened, with values of 59.8 +/- 6.6 mm (250 ms cycle; p < 0.01) and 44.9 +/- 5.1 mm (100 ms cycle; p < 0.01). In D2 (mean longitudinal increase in atrial wall length = 41 +/- 4%) the wavelength also shortened significantly, with values of 41.6 +/- 2.5 mm (250 ms cycle; p < 0.01 vs control) and 29.6 +/- 2.1 mm (100 ms cycle; p < 0.01 vs control). After suppressing atrial dilatation the wavelength was 65.7 +/- 8.0 mm (250 ms cycle, NS vs control) and 47.9 +/- 5.5 mm (100 ms cycle; NS vs control). The inducibility of rapid repetitive atrial responses increased during dilatation (22 episodes with over 30 consecutive repetitive responses in D1 [p < 0.01], 50 episodes in D2 [p < 0.001] vs 5 episodes under control conditions), and diminished after suppressing atrial dilatation (0 episodes with over 30 consecutive repetitive responses; p < 0.05). CONCLUSIONS: In the experimental model used, acute atrial dilatation produced a shortening in refractoriness and a decrease in conduction velocity. Both effects shortened the wavelength of the atrial activation process, facilitating the induction of atrial arrhythmias. The effects observed reverted upon suppressing atrial dilatation.

Animals↗
PubMed1998

Prediction equations for plethysmographic lung volumes.

Due to the lack of information of reference values for plethysmographic lung volumes, standardized measurements were carried out on a selected sample of 482 healthy non-smoking volunteers (300 men and 182 women), aged 20-70 years, living in the Barcelona area (Spain). Prediction equations using age, height and body surface area (BSA) as covariates were calculated for the subdivisions of lung volumes [TLC, IC, EVC, FRC, RV and RV/TLC (%)], separately for both sexes. Simple linear equations predicted lung volumes as well as more complex equational models. BSA correction was useful for FRC but not for the other parameters. Our predicted FRC was up to 10% higher (mean 256 ml) than the FRC estimated by other studies using gas dilution techniques, but showed an acceptable agreement with the plethysmographic measurements carried out in an independent sample of 94 healthy non-smokers (42 men and 52 women) from Barcelona using different equipment. The present study provides an internally consistent set of prediction equations for static lung volumes. Differences in predicted FRC between the present study and other reference values obtained using gas dilution measurements should be attributed to the method of measurement.

Adult↗
PubMed1998

Acute effects of radiofrequency ablation upon atrial conduction in proximity to the lesion site.

The electrophysiological effects of RF ablation upon the areas in proximity to the lesioned zones have not yet been well characterized. An experimental model is used to investigate atrial conduction in the boundaries of RF damaged zones. In 11 isolated and perfused rabbit hearts, endocardial atrial electrograms were recorded using an 80-lead multiple electrode positioned in the left atrium. Both before and after the RF application (5 W, 8 s, 1-mm diameter unipolar epicardial electrode) in the mid-portion of the free left atrial wall, measurements were made of conduction time from the pacing zone (posterior wall of the left atrium) to three points between 7.5 and 7.9 mm distal to the damaged zone. Conduction velocity and the direction of the activation propagation vector were determined in ten groups of four electrodes positioned around the damaged zone, and at the left atrial appendage. The mean diameter (+/- SEM) of the transmural lesions produced by RF ablation and defined by macroscopic examination was 4.2 +/- 0.2 mm. The conduction times to the three points distal to the lesion site were significantly prolonged as a result of RF ablation; 7.6 +/- 0.4, 7.4 +/- 0.5, and 6.9 +/- 1.0 ms (control); and 11.3 +/- 1.0 (P < or = 0.01), 11.1 +/- 1.3 (P < 0.01), 10.6 +/- 1.4 ms (P < 0.05) (post-RF). The differences between the conduction velocities determined in the areas surrounding the lesion, before and after RF application, failed to reach statistical significance: 86.2 +/- 6.5 cm/s (control) versus 75.5 +/- 5.7 cm/s (post-RF) (NS). After RF, significant variations were only observed in the direction of impulse propagation in the proximal-inferior quadrant adjacent to the lesion site, the difference being -61 degrees +/- 18 degrees (P < 0.02). In 2 of 4 experiments in which the lesion size was increased by a second RF application (5 W, 16 s), tachycardias with activation sequence around the lesion could be induced, with cycle lengths of 56 and 50 ms, respectively. In the atrial wall, the conduction times to the regions distal to the RF lesion are significantly prolonged. No significant changes are observed in conduction velocity in the areas in proximity to the lesion. Prolonged conduction to the areas distal to the ablation site is due to the lengthened pathway traveled by the impulses in reaching these areas. Tachycardias with activation patterns that suggest reentry around the RF damaged zone may be induced.

Animals↗
PubMed1998

Quantification of the modifications in the dominant frequency of ventricular fibrillation under conditions of ischemia and reperfusion: an experimental study.

The characteristics of ventricular fibrillatory signals vary as a function of the time elapsed from the onset of arrhythmia and the maneuvers used to maintain coronary perfusion. The dominant frequency (FrD) of the power spectrum of ventricular fibrillation (VF) is known to decrease after interrupting coronary perfusion, though the corresponding recovery process upon reestablishing coronary flow has not been quantified to date. With the aim of investigating the recovery of the FrD during reperfusion after a brief ischemic period, 11 isolated and perfused rabbit heart preparations were used to analyze the signals obtained with three unipolar epicardial electrodes (E1-E3) and a bipolar electrode immersed in the thermostatized organ bath (E4), following the electrical induction of VF. Recordings were made under conditions of maintained coronary perfusion (5 min), upon interrupting perfusion (15 min), and after reperfusion (5 min). FrD was determined using Welch's method. The variations in FrD were quantified during both ischemia and reperfusion, based on an exponential model deltaFrD = A exp (-t/C). During ischemia deltaFrD is the difference between FrD and the minimum value, while t is the time elapsed from the interruption of coronary perfusion. During reperfusion deltaFrD is the difference between the maximum value and FrD, while t is the time elapsed from the restoration of perfusion. A is one of the constants of the model, and C is the time constant. FrD exhibited respective initial values of 16.20 +/- 1.67, 16.03 +/- 1.38, and 16.03 +/- 1.80 Hz in the epicardial leads, and 15.09 +/- 1.07 Hz in the bipolar lead within the bath. No significant variations were observed during maintained coronary perfusion. The fit of the FrD variations to the model during ischemia and reperfusion proved significant in nine experiments. The mean time constants C obtained on fitting to the model during ischemia were as follows: E1 = 294.4 +/- 75.6, E2 = 225.7 +/- 48.5, E3 = 327.4 +/- 79.7, and E4 = 298.7 +/- 43.9 seconds. The mean values of C obtained during reperfusion, and the significance of the differences with respect to the ischemic period were: E1 = 57.5 +/- 8.4 (P < 0.01), E2 = 64.5 +/- 11.2 (P < 0.01), E3 = 80.7 +/- 13.3 (P < 0.01), and E4 = 74.9 +/- 13.6 (P < 0.0001). The time course variations of the FrD of the VF power spectrum fit an exponential model during ischemia and reperfusion. The time constants of the model during reperfusion after a brief ischemic period are significantly shorter than those obtained during ischemia.

Animals↗
PubMed1998

Malignant pleural effusion: prognostic factors for survival and response to chemical pleurodesis in a series of 120 cases.

Chemical pleurodesis is an effective treatment of malignant pleural effusions, but indications must be individualised to optimise its results. The aim of the present study was to investigate the relationship of various prognostic features with both the response rate to pleurodesis and the probability of patient survival. A non-concurrent cohort study was carried out in which 120 evaluable patients with malignant pleural effusion underwent pleurodesis. Lung (40%), breast (26.6%), and unknown primary site (12.5%) carcinomas were the most frequent neoplasms. Clinical data and pleural fluid parameters were analysed. Median overall survival was 9 months. Pleural fluid glucose (< 60 mg/dl), Karnofsky performance status (< 70), size of the effusion in chest radiographs (massive effusion), pleural fluid pH (< 7.20), presence of concomitant alterations in chest radiographs, and pleural lactic acid dehydrogenase levels (> 600 U/l) showed a significant association with the probability of failure. Patients with these features, along with those having non-chemosensitive tumours (in particular, non-small cell lung cancer), had a significantly worse actuarial survival. This study confirms that some pretreatment clinical data and pleural fluid parameters can predict both the outcome of pleurodesis and the survival of patients with malignant pleural effusion.

Aged↗
PubMed1998

Fibronectin in bronchoalveolar lavage fluid in lung cancer: tumor or inflammatory marker?

OBJECTIVE: To evaluate the potential value of the level of fibronectin (FN) in the bronchoalveolar lavage fluid (BALF) as a lung tumor marker. METHOD: We compare the results of determinations in the tumor-bearing and tumor-free lungs of 38 patients with lung cancer, in 19 patients with benign lung diseases and in 13 healthy control subjects. FN was determined in BALF by a competitive ELISA and was also measured in plasma with a nephelometric assay. FN levels in BALF are expressed also referred to total protein content (ng FN/mg TP). RESULTS: The distribution of FN levels in BALF was not gaussian, and the levels in cancer patients were significantly greater than in healthy controls or in the contralateral lung. There was no significative difference in the levels in cancer compared with several benign conditions. In this study we observed a positive correlation between FN levels and total protein and polymorphonuclear leukocytes in BALF in the lung cancer and benign diseases group. CONCLUSION: These results do not support the possibility that FN levels in BALF were a general marker of lung cancer, and suggest that FN may mark the existence of pathologic lung processes associated with inflammation and, perhaps tissue repair after bronchopulmonary injury.

Aged↗
PubMed1998

Medical personnel and patient skill in the use of metered dose inhalers: a multicentric study. CESEA Group.

The objective was to evaluate the correctness of the inhalation technique in a nationwide sample of patients and medical personnel, in order to define targeted educational goals. A total of 1,640 volunteers (746 patients, 466 nurses and 428 physicians) were evaluated. Only 9% of patients, 15% of nurses and 28% of physicians showed a correct inhalation technique. Physicians performed significantly better (mean score 77 +/- 23) than nurses (71 +/- 22) and patients (62 +/- 26). Scores in general practitioners and pediatricians were significantly lower than those of chest physicians and allergists. In conclusion, proper use of metered dose inhalers (MDI) in patients and medical personnel is still faulty. Despite the physician's awareness of the importance of a correct inhalation technique in the use of MDI, this study shows severe deficiencies, showing the need for substantial changes in educational efforts, and particularly addressed to general practitioners.

Adult↗
PubMed1997

Role of infarction artery status in left ventricular remodeling after acute myocardial infarction.

The aim of this study was to evaluate the relation between the infarction artery status and left ventricular volumes, independently of regional ventricular dysfunction, at 4-6 weeks after a first myocardial infarction. The study group consisted of 100 patients, of whom 80 received thrombolytic treatment. Coronary and contrast left ventricular angiograms were performed at 36+/-5 days postinfarction. Left ventricular end-diastolic and end-systolic volumes were measured. The centerline chord motion method was used to calculate the extent of wall motion abnormality (percentage of chords with hypokinetic motion) and its severity (maximum units of S.D. below the normal wall motion reference). Minimum lumen diameter, patency and collateral flow in the infarction artery were also analyzed. Eight patients (group I) showed occlusion with poor collateral flow in the infarction artery, 22 patients (group II) occlusion with good collateral flow, 38 patients (group III) severe residual stenosis (minimum lumen diameter < or = 1 mm), and 32 patients (group IV) non-severe residual stenosis (minimum lumen diameter > 1 mm). Patients from group I presented greater wall motion abnormality in terms of both extent (P=0.005) and severity (P=0.007), and greater end-diastolic (P=0.07) and end-systolic (P=0.0008) volumes; there were no differences among groups II, III and IV. By stepwise multivariate regression analysis, the extent of wall motion abnormality was the main determinant of end-diastolic (P=0.0001) and end-systolic (P=0.0001) volumes; occlusion with poor collateral flow was also a significant independent factor for end-systolic volume (P=0.03). Total occlusion (including both with and without collaterals) and the minimum lumen diameter did not correlate with end-diastolic and end-systolic volumes. We concluded that (A) the extent of regional dysfunction is the primary determinant of left ventricular volumes at 4-6 weeks postinfarction. (B) The status of the infarction artery is a weak predictor of end-diastolic volume, which is the best descriptor of ventricular remodeling, although occlusion with poor collateral flow is associated to larger end-systolic volume.

Cardiac Volume↗
PubMed1997

[Evaluation of 6 portable meters for measuring peak expiratory flow].

The aim of this study was to evaluate six peak flow meters, comparing them to a flow signal recorded under laboratory and clinical conditions (LC and CC, respectively). The six peak flow meters studied were the PF-Control (A), the Personal Best (Healthscan) (B), the logarithmic scale and linear Vitalographs (Vitalograph) (C and D), the Miniwright (Airmed) (E), and the Assess (Healthscan) (F), LC: Readings were compared to those obtained with a computer-controlled syringe attached to a servomechanism (Pulmonary Waveform Generator System) at flow levels of 185, 302 and 595 L/m before and after clinical measurements. CC: Readings from each model, taken randomly and consecutively, were compared with those obtained by pneumotachometer in 50 individuals with different air flow levels (range 86 to 888 L/min), ending by repeating the measurement procedure with the first device used. The LC results were as follows: precision varied among the six models from 0.9% (F) to 9.4% (E), and in no case was there a statistically significant difference from the servosyringe reading; reproducibility (coefficient of variation) ranged from 0.7% (F) to 3.3% (B); stability after clinical testing showed results that differed from those of the servosyringe in a range of -18.3 L/min (A) to +16.7 L/min (B) and the difference was significant only for device B. The CC results were as follows: in comparison with the pneumotachometer readings, percent error was within NHLBI limits for devices A and B in excess of the limits for the other peak flow meters. Analysis of concordance showed that differences were related to level of flow for all devices except F and that measurement errors conformed to an equation of linear regression. We conclude that all the studied models give readings that are biased in direct proportion yo the flow measured. Precision was good and the devices remained stable over more than 200 readings, such that peak flow meters are appropriate for repeated measurements in a single patient.

Evaluation Studies as Topic↗