دستگاه مانیتورینگ حجم های تنفسی (Spirometer)
یکی دیگر از تجهیزات پزشکی که امروزه نقش به سزایی در تعیین بیماری های حاد دستگاه تنفسی دارد دستگاه مانیتورینگ حجم های تنفسی است که به وسیله ی آن می توان حجم تنفسی شخصی را اندازه گیری کرد و به واسطه تحلیل نتایج آن و مقایسه ی آن با مقادیر مورد انتظار می توان بیماری های ریوی از قبیل آسم و … را تشخیص داد.
انواع دستگاه مانیتورینگ حجم های تنفسی
دستگاه مانیتورینگ حجم های تنفسی در نوع ها و فن آوری های مختلف ارایه می شود.
جهت آشنایی با شکل کلاسیک و آشنایی با شماتیک دستگاه مانیتورینگ حجم های تنفسی می توان از نوع ابتدایی آن یعنی اسپیرومتر روان کننده با آب را مثال زد و تشریح نمود.
در دستگاه کلاسیک مانیتورینگ حجم های تنفسی یک ظرف پر از آب که به صورت استوانه ای است وجود دارد که یک سرپوش به صورت وارونه درون ظرف آب قرار می گیرد و یک لوله فضای هوای زیر سرپوش را به دهان شخص ( جهت عمل دم و بازدم ) متصل می کند.
انتهای سرپوش توسط یک نخ و قرقره به یک وزنه در حالت تعادل متصل شده است و در میان نخ یک قلم جهت ثبت گراف وجود دارد.
وقتی شخص عمل دم و بازدم را انجام می دهد به واسطه ی نیرویی که از طریق انجام دم و بازدم به سرپوش وارد می سازد سبب می گردد که وزنه از حالت تعادل خارج شده و به سمت بالا و پایین حرکت کند.
تغییرات حجم فضای زیر سرپوش
و تغییرات حجم فضای زیر سرپوش که عبارت است از همان تغییرات حجم تنفسی بر روی یک کاغذ متحرک توسط قلم دستگاه ثبت می گردد. در واقع این اساس کار مانیتورینگ حجم های تنفسی است ولی امروزه از فن آوری های جدید در این دستگاه استفاده شده است.
دستگاه مانیتورینگ حجم های تنفسی از یک قسمت که جهت رعایت نکات بهداشتی بر روی آن یک لوله ی مقوایی قرار می گیرد جهت انجام عمل دم و بازدم تشکیل شده در داخل همین قسمت از سنسورهایی تشکیل شده است که نسبت به هوای ورودی و خروجی حساس بوده و ورودی را به صورت سیگنالی به برد دستگاه اصلی که مجموعی از مدارات و میکروپروسسرهاست انتقال می دهد و سرانجام نتیجه به صورت گراف توسط مانیتوردستگاه نشان داده می شود که قابلیت پرینت را نیز دارا می باشد.
Spirometer
| Spirometer | |
|---|---|
| Medical diagnostics | |
Spirometer test
|
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| Purpose | measuring the volume of air inspired/expired by the lungs |
A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs.
A spirometer measures ventilation, the movement of air into and out of the lungs.
The spirogram will identify two different types of abnormal ventilation patterns, obstructive and restrictive.
There are various types of spirometers which use a number of different methods for measurement (pressure transducers, ultrasonic, water gauge)
.
Pulmonary function tests
A spirometer is the main piece of equipment used for basic Pulmonary Function Tests (PFTs).
Lung diseases such as asthma, bronchitis, and emphysema can be ruled out from the tests. In addition, a spirometer is often used for finding the cause of shortness of breath, assessing the effect of contaminants on lung function, the effect of medication, and evaluating progress for disease treatment
Early development
The earliest attempt to measure lung volume can be dated back to the period A.D.
129-200. Claudius Galen, a Roman doctor and philosopher, did a volumetric experiment on human ventilation.
He had a boy breathe in and out of a bladder and found that the volume did not change. The experiment proved inconclusive.
- 1681, Borelli tried to measure the volume of air inspired in one breath.
- He assembled a cylindrical tube partially filled with water, with an open water source entering the bottom of the cylinder. He occluded his nostrils, inhaled through an outlet at the top of the cylinder and measured the volume of air displaced by water.
- This technique is very important in getting parameters of lung volume nowadays.
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Nineteenth century
- 1813, Kentish E used a simple “Pulmometer” to study the effect of diseases on pulmonary lung volume.
- He used an inverted graduated bell jar standing in water, with an outlet at the top of the bell jar controlled by a tap.
- The volume of air was measured in units of pints.
- 1831, Thackrah C.T described a “Pulmometer” similar to that of Kentish.
- He portrayed the device as a bell jar with an opening for the air to enter from below.
- There was no correction for pressure. Therefore, the spirometer not only measured the respiratory volume, but also the strength of the respiratory muscles.
- 1845, Vierordt in his book named “Physiologie des Athmens mit besonderer Rücksicht auf die Auscheidung der Kohlensäure” discussed his interest in measuring the volume of expiration accurately.
- He also completed accurate measures of other volume parameters by using his “Expirator”. Some of the parameters described by him are used today, including residual volume and vital capacity.
- 1846 The water spirometer measuring vital capacity was developed by a surgeon named John Hutchinson.
- He invented a calibrated bell inverted in water, which was used to capture the volume of air exhaled by a person. Hutchinson published his paper about his water spirometer and the measurements he had taken from over 4,000 subjects,describing the direct relationship between vital capacity and height and the inverse relationship between vital capacity and age.
Interpreting Spirometry
Even with the numerical precision that a spirometer can provide, determining pulmonary function relies on differentiating the abnormal from the normal.
Measurements of lung function can vary both within and among groups of people, individuals, and spirometer devices.
Lung capacity, for instance, may vary temporally, increasing and then decreasing in one person’s lifetime. As a result, ideas about what constitutes “normal” are based on one’s understanding about the sources of variabilities and can be left to interpretation.
Traditionally, sources of variation have been understood in discrete categories, such as age, height, weight, gender, geographical region (altitude), and race or ethnicity.Global efforts have been made in the early 20th century to standardize these sources to enable proper diagnosis and accurate evaluation of pulmonary function.
However, rather than further aiming to understand the causes of such variations, the primary approach for dealing with observed differences in lung capacity has been to “correct for” them. Utilizing results from comparative population studies, attributes are empirically factored together into a “correction factor.”
This number is then utilized to form a personalized ‘reference value’ that defines what is considered normal for one individual.
Practitioners may thereby find the percent deviation from this predicted value, known as ‘percent of predicted,’ and determine whether someone’s lung function is abnormally poor or excellent.