Peak Flow as a Measure of the Speed - Essay Example

Peak Flow Peak flow is a measure of the speed of air coming out of lungs. This way, actually, we assess the diameter and patency of the airways in the lungs. Peak flow readings are influenced by time of the day when it is measured, by some physiological characteristics such as, age, sex, height and by certain pathological conditions, like: asthma, and other pulmonary obstructive diseases (Peak flow 2006). Change in peak flow can also occur during different timings in the day. Although the position of the subject in normal situations at the time of exhaling air in spirometer has got no effect on the readings (Vaswani 2005) (Miller 2005) but other physiological burdens, like pregnancy has shown some effects on the values of expiratory flow which relates to the gestational age as well as position of the pregnant women (Harirah 2005). A spirometer is the equipment used in the measurement of peak flow. This apparatus measure the amount of air, which is taken in during inspiration phase and expired out over a specified time. Along with the amount, it also keeps a record of the speed, which is then converted to rate of air inspired and expired (Spirometer 2006) (Pederson 1996). Stating more scientifically, it measures lung functions specifically the measurement of the amount (volume) and /or speed (flow) of air that can be inhaled and exhaled. Spirometry is the process of measuring pulmonary function tests (PFTs) (Spirometry 2006). The process is an important monitoring tool for the diagnosis and prognosis of pulmonary obstructive diseases. Results are, usually, given as the percentages of predicted values for the patients of similar physiological characteristics. The results approaching 100 % predicted are the most normal but those individuals who show over 80% may be considered normal. The review by a medical doctor, further, validates the results (Spirometry 2006). The use of technique in self recording of peak expiratory flow is important and may change with different subjects and even at different clinical places (Gannon 1999). The training of the proper use of spirometer is also important, which has reflected different level of learning between the two sex groups (Self 2005). Methodology This is an in house activity of collecting required information. All of the students present in the class (27) were involved in the process of data collection as subjects. To get more reliable calculations, the procedure of spriometry, has to be repeated three times per individual so every student went through the process thrice, each time followed by measurement of her/his height. For record of the reading and analytical purposes the highest value among all three is taken. To compare and reduce the possibility of error, two independent reviewers coordinated the experiment. We analysed these data at three different levels. Spirometry by the two reviewers was separated by various activities, like various phases forceful expiration, measurement of height etc. So we compared the highest readings from the two reviewers by applying paired t-test (Rosner 1995) (Saunder 1994). We divided the peak flow values in two categories, category 1 for lowest level to 540 and category to from 541 to the highest level. Then we looked for the association of the sex (1=female and 2=male) for the categories of the peak flow values. We applied chi-square test at this level(Rosner 1995) (Saunder 1994). As the two reviewers took part in the procedure as independent assessors so we analysed the level of agreement between the two reviewers by using Kappa statistics (Rosner 1995) (Saunder 1994). To fulfil the requirement of both variables to be categorical we managed the datasets to change the peak flow from continuous variable to the categorical variable. Results Table 1 shows the results of paired t-test performed to compare the mean values of two measurements of peak expiratory flow measured at two different time period with some activities performed in between. There was no difference found in the two values of mean peak expiratory flow (p-value = 0.574). This means the intervening time and some activities could not affect the peak flow to a significant level. Before looking for this Table1: Paired t-test to compare the mean peak expiratory flow measured before and after some period with activity for students in the class Peak Flow 1 Peak Flow 2 p-value Mean 545.58 545.19 0.574 SE (Mean) 13.64 13.81 difference we also assessed the correlations between the two samples which was found statistically significant concluding that both the samples are highly correlated (p-value 0.000) Table 2: Association between sex and peak expiratory flow Variable/Factors Gender p-value Male Female Peak Flow 540 540 - 9 13 5 0.000 Table 2 explains the association between sex and peak expiratory flow. This table states that all of the males were in the second group of peak flow means that all males had peak flow of more than 540 while there were more than double the females who belonged to the first category. The difference was statistically significant (p-value 0.000). Male showed strong association with high peak flow as compared to females. Table 3 gives us the analysis using kappa statistics. Through the use of this statistics we can look for the agreement between the two reviewers for assessment of a common character, which is assessed, by the both reviewer. Kappa statistics (p-value 0.000) states highly significant reproducibility between the two reviewers for the measurement of peak flow. Table 3. Level of agreement between two reviewers Factors 2nd reviewer Peak Flow 540 540 p-value 1st reviewer Peak Flow 540 540 13 - - 14 0.000 Discussion Peak flow is a good measure of lung functions. Through spirometry, patients of chronic obstructive pulmonary diseases (COPD) can monitor their status of airways patency. Peak expiratory flow depends on age, sex, height, time in the day or evening and some pulmonary obstructive diseases. Our results show association of male sex with higher level of peak flow values, which is consistent with the normal ranges (table 2). Female has got lesser values for peak flow as compared to males of the same age and height. For repeated measurements to be used in any datasets, it is customary that they are alike if measured in the similar environment. Our analysis of peak flow for the highest readings among three measurements by the two reviewers supported that values were not different (table1). Before this analysis, we were able to find strong correlation between the two readings; this factor also supported our findings. Kappa statistics is used as an important test for the assessment of similarity and agreement between the two reviewers. This test further supports our datasets as far as the quality issue in data management is concerned as the test was in favour of the highly significant agreement (table3). Limitations Sample size was small although we could run all the analyses but. Subsample of male was again half (9) of the female category (18), which may not capture the representation of male category. We make categories of peak flow almost in the midway between the two extremes. This is why there were two groups of concordance and we cold not find any values out of these two groups. Small sample size further lead to this issue. References Peak Flow, 2006, Doctoronline [Online] http://www.doctoronline.nhs.uk/masterwebsite1Asp/targets/testandprocedures/proced/... 31 March 2006 Gannon, P., Belcher, J., Pantin, C. & Burge, P. 1999, The effect of patient technique and training on the accuracy of self-recorded peak expiratory flow. European Respiratory Journal Vol 14, pp. 28-31 Harirah, H., Donia, S., Nasrallah, F., Saade, G. & Belfort, M. 2005, Effect of gestational age and position on peak expiratory flow rate: a longitudinal study. Obstetric and gynecology Vol 105, no. 2, pp. 372-6 Miller, M., Crao, R., Hankinson, J., Brusasco, V., Burgos, F., Casaburi, R., Coates, A., Enrigth, P., Grinten, V., Gustafsson, P., Jensen, R., Johnson, D., MacINtyre, N., McKay, R., Navajas, D., Pedersen, O., Pellegrino, R., Viegi, G & Wanger, J. 2005, General considerations for lung function testing. European Respiratory Journal. Vol 26, pp 153-161 Pedersen, O., Rasmussen, T., Omland, Sigsgaard, T., Quanjer, H. & Miller, M. 1996, Peak expiratory flow and the resistence of the mini-Wright peak flow meter. European Respiratory Journal. Vol 9, pp828-833 Polit D.F. & Hungler B.P. Writing a research report in nursing research: Principles and Methods. 1995, 5th edition, J.B. Lippincott Compnay, Philadelphia Rosner B. Fundamentals of biostatistics. 1995. 4th edition, Duxbury Press, an international Thomson Publishing Company, Tokyo. Saunder, B.D & Trapp, RG. Basic & clinical biostatistics. 1994 2nd edition, the Lange Medical book, Appleton and Lange, Norwalk, Connecticut Self, T., Nolan, S., Weibel, J., HIlaire, M., Franks, A., Finch, C. & Tolley, E. 2005, gender differences in the use of peak flow meters and their effect on peak expiratory flow. Pharmacology Vol.25, no. 4, pp. 526-30 Spirometer, 2006, Wikipedia, the free encyclopedia. [Online]: http://en.wikipedia.org/wiki/Spirometr 31March 2006 Spriometry, 2006, Wikipedia, the free encyclopedia. [Online]: http://en.wikipedia.org/wiki/Spirometry 31 March 2006 SPSS (10.0) for windows. Chicago, IL: SPSS Inc, 1999 Vaswani, R., Moy, R. & Vaswani, S. 2005, Evaluation of factors affecting peak expiratory flow in healthy adults: is it necessary to stand up Journal of Asthma Vol 42, no 9, pp.793-4 Read More