Percentage Of Predicted Value Research Articles

An Assessment of PeaK Expiratory Flow as a Surrogate Measurement of FEV1 in Stable Asthmatic Children

We examined the relationship over 24 hours between percent-predicted values (PPV) of peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) in a group of 23 stable untreated asthmatic children 6 to 17 years of age by means of regression analysis as well as the percentage difference between the PPV of these two measurements. Although the Pearson correlation coefficient between the PPV was consistently high, ranging between 0.854 and 0.892, the assumption that such a finding substantiates the substitution of PEF for FEV1 is called into question. Over 50 percent of the subjects displayed a 10 percent or greater difference in the PPV between the two measurements, regardless of the time of day the two respiratory variable were determined, while over one-third of all subjects evidenced a 20 percent or greater discrepancy between the PPV of the two measures. While, on a group basis, there was no statistically significant difference in the mean percentage difference over 24 hours between the PPV of FEV1, when compared with the corresponding measurement of PEF, reliance on PEF alone in individual subjects may result in a false impression of the patency of the airways in comparison to the FEV1.

Total deposition of ultrafine sodium chloride particles in human lungs.

The total deposition of monodisperse, 0.026-0.19 micron (dry volume equivalent diameter) sodium chloride particles in the lungs of five healthy subjects, who breathed orally, was measured. For a tidal volume of 1,000 ml and flow rate of 500 ml/s, the percentages deposited were: 37.2 +/- 8.4% (mean +/- SD) for 0.026 micron, 23.8 +/- 3.3% for 0.051 micron, 22.8 +/- 3.1% for 0.096 micron, and 31.8 +/- 6.2% for 0.19 micron particles. The deposition minimum corresponded to a particle size of approximately 0.08 micron. Deposition did not correlate with measures of lung volume or body size but did correlate with forced expired flow rate after 75% of forced vital capacity (FVC) exhaled (FEF 75%/FVC) and with percent-predicted values for FEF 25-75% and FEF 75%. Lengthening the breathing period from 4 to 8 s/breath while maintaining flow rate at 500 ml/s caused an additional 11.3 +/- 3.1% of the inhaled particles to deposit. Sedimentation and diffusion were found to be the principal deposition mechanisms. These hygroscopic particles deposited according to sizes they would attain in air with a relative humidity between 96 and 100%.

Noninvasive detection of left ventricular dysfunction with a portable electrocardiographic gated scintillation probe device

A comparison of left ventricular function data derived from a low cost, portable electrocardiographic gated scintillation probe (nuclear stethoscope) with conventional scintiangiographic data was performed in 68 patients. Ejection fraction correlation (r = 0.86, p < 0.005) was better in patients with uniform wall motion than in those with regional asynergy (r = 0.68 p < 0.01). Probe variables reflecting systolic emptying rates, diastolic filling rates and timing intervals, and relative volumes analyzed in combination provided 100 percent sensitivity, specificity, and predictive value in detecting abnormal left ventricular performance. The results suggest that radionuclide angiography with an electrocardiographic gated scintillation probe is a sensitive, rapid and relatively inexpensive portable method of screening for cardiac dysfunction with a yield similar to that from the more costly gamma camera derived scintiangiogram.

Breathing pattern and hypercapnia in patients with obstructive pulmonary disease.

Pulmonary gas exchange and breathing pattern were studied in 91 patients with chronic obstructive pulmonary disease breathing room air. All patients were clinically and functionally stable at the t...

Predictive accuracy of [formula omitted] ratio, Q-Tc interval, S-T depression and R wave amplitude during stress testing

The sensitivity, specificity and predictive value for Q-X Q-T ratio, Q-Tc interval, S-T segment depression, R wave change and various combinations of these criteria were compared in 50 healthy, normal persons and 50 persons with angiographic coronary artery disease defined as 70 percent or greater stenosis of one or more major coronary vessels. Use of a positive S-T segment response and an increase or no change in R wave amplitude as criteria for coronary artery disease resulted in 84 percent sensitivity and 96 percent specificity levels and a 95 percent predictive value. The Q-X Q-T and Q-Tc criteria offered no improvement in sensitivity, specificity or predictive value over S-T segment depression. When the study group was limited to 74 persons, 36 without and 38 with angiographically significant coronary artery disease, a Q-Tc interval of 1.08 or more in combination with either slowly or rapidly upsloping S-T depression after exercise predicted coronary disease at a sensitivity level of 76 percent compared with 50 percent with use of the S-T segment alone ( P < 0.05). Specificity was not significantly reduced (89 percent for the S-T segment alone, 79 percent with the addition of the Q-Tc interval) ( P > 0.05). Use of the R wave response with the presence of upsloping S-T segment depression of 1.5 mm or more 80 msec from the J point improved the sensitivity level from 50 percent for S-T depression alone to 76 percent ( P < 0.05); specificity and predictive value were not significantly reduced (81 percent for each [ P > 0.05]). The Q-X Q-T ratio could be measured in only 55 patients (74 percent) and offered no improvement over S-T segment depression. Upsloping S-T segment depression of 1.5 mm or more 80 msec from the J point in the immediate postexercise period is most likely a positive test for ischemia. An increase or no change in R wave amplitude in response to exercise in these patients regardless of the degree of S-T segment depression is probably indicative of coronary artery disease. In patients with upsloping S-T segment depression, a Q-Tc interval of 1.08 or more in the immediate postexercise period is a useful measurement in predicting coronary artery disease.

Reliability of single-lead and multiple-lead electrocardiography during and after exercise.

To define the number, type, and criteria for interpretation of electrocardiographic leads yielding the most reliable results during and after exercise, 203 men were studied. Twelve-lead exercise electrocardiograms (including lead CM 5 ) and coronary arteriograms were correlated. Depression of the S-T segment that was present only during exercise was of doubtful significance. Analysis of ECGs after exercise revealed that only leads V 5 , V 6 , and CM5 had acceptable sensitivity (61, 53, and 60 percent, respectively). Analysis with multiple leads increased the sensitivity of exercise tests to 65 percent Lead V5 correctly identified 39 percent (17) of the 44 patients with single-vessel disease and 74 percent (49/66) of those with multiple-vessel disease. The predictive values of interpretations based on lead V 5 and multiple leads were not significantly different (84 percent [67/80] and 82 percent [71/88], respectively). The highest predictive values were in lead 2 (88 percent; 37/42) and lead V 4 (88 percent; 45/51). Sensitivity was inversely related to the degree of ST-segment depression required for abnormality. Specificity was directly related. Predictive value was directly related in all except leads V 4 and CM 5 . A predictive value of 100 percent was manifested by the various leads with the following amounts of ST-segment depression: lead V 3 , ≥ 2 mm; leads V 4 , V 6 , and aVF, ≥ 3 mm; and lead V 5 , ≥ 4 mm. Even with ST-segment depression of 4 mm or more, lead CM5 had only 83 percent predictive value. Using analysis with multiple leads, all patients with abnormal findings on maximal exercise tests of less than six minutes in duration had significant disease.

Reliability of Single-Lead and Multiple-Lead Electrocardiography during and after Exercise

To define the number, type, and criteria for interpretation of electrocardiographic leads yielding the most reliable results during and after exercise, 203 men were studied. Twelve-lead exercise electrocardiograms (including lead CM 5 ) and coronary arteriograms were correlated. Depression of the S-T segment that was present only during exercise was of doubtful significance. Analysis of ECGs after exercise revealed that only leads V 5 , V 6 , and CM5 had acceptable sensitivity (61, 53, and 60 percent, respectively). Analysis with multiple leads increased the sensitivity of exercise tests to 65 percent Lead V5 correctly identified 39 percent (17) of the 44 patients with single-vessel disease and 74 percent (49/66) of those with multiple-vessel disease. The predictive values of interpretations based on lead V 5 and multiple leads were not significantly different (84 percent [67/80] and 82 percent [71/88], respectively). The highest predictive values were in lead 2 (88 percent; 37/42) and lead V 4 (88 percent; 45/51). Sensitivity was inversely related to the degree of ST-segment depression required for abnormality. Specificity was directly related. Predictive value was directly related in all except leads V 4 and CM 5 . A predictive value of 100 percent was manifested by the various leads with the following amounts of ST-segment depression: lead V 3 , ≥ 2 mm; leads V 4 , V 6 , and aVF, ≥ 3 mm; and lead V 5 , ≥ 4 mm. Even with ST-segment depression of 4 mm or more, lead CM5 had only 83 percent predictive value. Using analysis with multiple leads, all patients with abnormal findings on maximal exercise tests of less than six minutes in duration had significant disease.

PEFR and FEF&lt;sub&gt;25-75&lt;/sub&gt; in type 2 diabetes mellitus and their relationships with its duration

Background: Diabetes mellitus is a major public health problem with increasing incidence worldwideand long term complications of various organs including lungs. The magnitude of the complicationsof this disease is related to its duration. Objective: To observe PEFR and FEF25-75 in type 2 diabeticmale and their relationship with duration of the disease. Methods: This cross sectional study wascarried out in the Department of Physiology, BSMMU, Dhaka, from 1st July 2007 to 30th June 2008 on60 type 2 diabetic, non smoker, male of 40-60 years old. For comparison, 30 age, BMI and socioeconomicstatus matched apparently healthy non diabetic subjects were also studied. Based on the duration ofdisease, diabetic patients were divided into B1 (5-10 years) and B2 (10-20 years). PEFR and FEF25-75 ofall the subjects were measured by an electronic spirometer. Data were analyzed by One way ANOVA,Unpaired Student's 't' and Pearson's correlation coefficient tests. Results: The mean percentage ofpredicted values of PEFR and FEF25-75 in non diabetic male were within normal ranges. But, both theparameters were significantly (p&lt;0.001) lower in both the groups of type 2 diabetic male compared tothose of non diabetic male. Again, the PEFR and FEF25-75 were lower in the patients of longer durationcompared to those of shorter duration but the differences were not significant. However, PEFR wasnegatively correlated and FEF25-75 was positively correlated with shorter duration of diabetes and therelationships were nonsignificant. On the other hand, both the parameters were negatively correlatedwith longer duration of diabetes while only PEFR showed significant (p&lt;0.01) relationship. Conclusion:The PEFR and FEF25-75 may be lower in type 2 diabetic male, which are inversely related to theduration of the disease.Key words: PEFR; FEF25-75; Diabetes Mellitus.DOI: 10.3329/jbsp.v5i1.5413J Bangladesh Soc Physiol. 2010 June; 5(1): 14-19