Ventilatory Function - Report Example

Ventilatory Function Introduction Ventilation is the process of moving gases into and out of the lungs. Ventilation requires co-ordination of the muscular and elastic properties of the lung and thorax, as well as intact innervation. The major inspiratory muscle of respiration is the diaphragm. Spirometry is used to measure the volume of air entering or leaving the lungs. Variation in lung volume may be associated with health stastes such as pregnancy, exercise, obesity or obstructive and restructive condition of the lungs. The amount of surfactant, degree of compliance and strength of respiratory muscles can affect pressures and volumes with in the lungs.1 Lung function test can be grouped as follows 1. to test the effeciancy of the ventilation ( ie, mechanical aspects of respiration). 2. to test the efficiency of gas exchange of the alveolai level 3. efficiency of respiratory system in relation to exercise. 4. Blood analysis ( Estimation of a. PaCO2 b. PaO2 c.Blood pH).2 Method Measure each student’s height and weight and record these values. Using the sliding anthropometer take a measure of everyone’s chest width. Using the tape measure, take a chest circumference. Ideally these measures should be made while the subject is standing expect for possibly the MVV. Forced vital capacity 1. With the mouthpiece in your mouth , breathe normally for some seconds 2. Do a maximal inspiration 3. Do a maximal forced expiration 4. Do a maximal forced inspiration ( optional ) 5. Breathe normally ( optional) 6. Remove the mouthpiece Repeat this test 3 times Slow vital capacity (expiratory) 1. place the mouthpiece in your mouth and breathe normally until the message “carry out slow vital capacity” is prompted. 2. Carry out a “maximal slow inspiration” 3. Carry out a “maximal slow expiration” 4. Breathe normally Repeat this 3 times. Maximal voluntary ventilation Breathe as deeply as possible at a rate of 30 breaths/min.- This is a rapid rate.This rate of breathing may make some people dizzy. RESULT The demographic details of the participants are listed in table-1. The spirometric data of six subjects are listed in table-2.the parameters such as FVC, FEV1 and EVC slightly deviate from the predicted value whereas the actual MVV deviates by 23.2% from the predicted value. There were no significant differences between the actual and predicted values for FVC, FEV1 and EVC. Figure 1 shows the comparison of mean values of actual predicted parameters. Table 1: Demographic Details (N=6) Subject Age Gender Height (Cm) Weight (Kg) BMI (Kg/m2) Chest width Chest Circumference 1 22 Male 175 72.5 23.67 28.50 92 2 23 Female 176.3 74 24.16 30.50 87.5 3 23 Female 172 97 32.77 35 110 4 27 Male 173 73.5 24.56 33 98 5 26 Male 185 77.5 22.64 33 98 6 40 Female 179.7 72 22.30 31 95 Table 2: Actual and Predicted Parameters (N=6) Parameter Subject 1 Subject 2 Subject 3 Subject 4 Subject 5 Subject 6 A P A P A P A P A P A P FVC 4.47 5.17 4.55 4.32 4.82 3.50 4.97 4.92 4.40 5.64 3.76 4.03 FEV1 4.01 3.91 3.83 3.79 4.32 3.19 4.26 4.17 4.39 4.71 3.68 3.50 FIV1 2.23 2.38 5.41 3.63 3.04 2.49 FET/100% 0.2 0.1 0.3 0.3 0.3 0.3 EVC 4.58 5.41 4.27 4.34 4.19 4.10 5.27 5.15 4.88 5.91 3.66 4.05 VT 0.51 0.73 0.49 0.69 0.76 0.67 MVV 100.2 152.3 102.4 127.8 108.3 123.5 118.8 145.9 80 161 99 119 MVT 3.20 4.21 4.27 4.61 2.53 3.45 A - Actual, P - Predicted FVC - Functional Vital Capacity in 1 second FIV1 - Forced Inspiratory Volume in 1 second FET/100% - Forced Expiratory Time EVC – Expiratory Vital Capacity VT – Tidal Volume MVV – Maximum Voluntary Ventilation MVT – Tidal Volume during Maximum Voluntary Ventilation Discussion The tidal volume is the volume of air inspired or expired during normal breathing.The volume of air blown off after maximal inspiration to full expiration is define as the vital capacity (VC). The residual volume (RV) is the volume of air left in the lung after maximal expiration. The volume of air left after a normal expiration is the functional residual capacity(FRC). Total lung capacity (TLC) is the vital capacity plus the RV. Patients with obstructive lung disease have difficulty with expiration ; therefore they tend to have a decreased VC, an increased RV, and a normal TLC. The single most useful test for ventilatory dysfunction is the FEV. The FEV is measured by having the patient exhale into the Spiro meter as forcefully and completely as possible after maximal inspiration. The resulting volume curve is plotted against time so that expiratory flow can be estimated. The FEV1 of the forced vital capacity commonly is measured to determine the dynamic performance of the lung in moving air. The FEV1 usually is expressed as a percentage of the total volume of air exhaled and is reported as the FEV1 :FVC ratio . Health persons generally can exhale at least 75% to 80% of their VC in 1 second and almost all of it in 3 seconds. Thus, the FEV1 normally is 80% of the FVC. The patient’s breathing ability is compared against “predicted normal” values for patients with similar physiological characteristics because lung volumes depend on age, race, gender, height and weight. For example , an average-sized young adult male may have an FVC of 4 to 5 L and a corresponding FEV1 and the FVC are the most reproducible of the pulmonary function tests. Flows at less than 75% of FVC are limited by airway compressibility and therefore determined by the elastic recoil force of the lung and the resistance to flow upstream of the collapse. The PEF is the maximal rate of flow that can be produced during the forced expiration. The PEF can be measured easily with various handheld peak flow meters and commonly is used in emergency departments and clinics to quickly and objectively assess the effectiveness of bronchodilators in the treatment of acute asthma attacks. Peak flow meters also can be used at home by patients with asthma to assess chronic therapy. The changes in PEF generally parallel those of the FEV1 ; however, the PEF is a less reproducible measure than the FEV1 . A healthy , average-sized young adult male typically has a PEF of 550 to 700 L/minute.3 In normal persons the value of VC should be about 3.5L to 4.5L approximately. VC is lower in female.VC is low in old people.2 Breathing exercises are designed to aid the client to achieve more efficient and controlled ventilations, to decrease the work of breathing, and to correct respiratory defects. The effects of exercise include increased respiratory rate and death followed by quicker return to resting state, improved alveolar ventilation, and improved diaphragmatic excursion.4These exercise promote maximum alveolar inflation; promote muscle relaxation; relieve anxiety; eliminate useless and uncoordinated pattern of respiratory muscle activity. The volume of each breath is referred to as the tidal volume. If the patient is breathing via an endotracteal tube or tracheotomy, the respirometer is attached to a face mask, which is place over the nose and the mouth so that it is airtight and the exhaled volume is measured as before. Hand held electronic respirometers that provide digital readouts of lung volume are also available. The tidal volume may vary from breath to breath. To make the measurements move reliable, the volumes of reversal breather are measured and the range of tidal volume together with the average tidal volume are noted. The normal tidal volume is 5 to 8 mL per kilogram of body weight.5 During the process of normal quite breathing, about 500mL of air moves into respiratory passageways with each inspiration. The same amount moves out with each expiration. This volume of air inspired (or expired) is called tidal volume. Only about 350mL of the tidal volume actually reacts the alveoli. The other 150mL remains in the air . Spaces of the more pharynx, larynx, trachea and bronchi and is known as dead air volume. The total are taken in during 1 minute is called the minute volume of respiration. It is calculated by multiplying the tidal volume by the normal breathing rate per minute. An average volume would be 500mL times 12 respirations per minute, or 6000mL/min. By taking a very deep breath ,we can inspire a good deal more than 500mL. This excess inhaled air called inspiratory reserve volume, averages 3100 above the 599mL of the tidal volume . Thus the respiratory system can pull in as much as 3600mL of air. If we inhale normally and then exhale as forcibly as possible, we should be able to push out 1200mL of air in addition to the tidal volume. This extra 1200mL is called the respiratory reserve volume.6 Vital capacity is the volume of air breathed out by the most forcible expiratory effort after the maximal inspiration. In normal persons its value should be about 3.5 to 4.5 L approx. VC depends on many factors. Normally, VC is about 2.6 L/sq.meter of body surface in male and 21 L/sq meter in female. Measurement of expansion of chest is often done during recruitment in the police or in routine annual health check up in schools. This is done in the hope of getting an idea about the VC (greater expansion is equal to greater VC). However, this is not a good index of VC. As VC is an index of physical fitness, greater chest expansion, according to their view, indicator greater physical fitness. The volume of air breathed in and out and the number of breaths per minute varies from one individual to another according to age, size and activity. Normal, breathing gives about 15 complete cycles per minute in the adult.2 MVV(maximum ventilatory volume), also called MBC or (maximum breathing capacity) is the volume of air that can be breathed out by giving maximum effort in voluntary hyperventilation in one minute. Normal value is as 100L/min but often more (e.g. 150L/min) in lower fully built young health males. In water filled spirometer one makes voluntary hyperventilation for 15sec and this value  4 gives the MVV/min.7 References 1. Potter, P.A, and A.G.Perry. Fundamentals of Nursery, 5th Edition, Mosby, Inc, Missouri, 2001, 999, 1129-1131. 2. Chaudhari, S.K. Concise Medical Physiology, 3rd Edition, New central book Agency(p) Ltd, Calcutta, 2001, 153-156. 3. Kimble MH Koda, Lloyd YY, Wayne AK, BJ Kradjan, Brian KA and Robin LC. Applied Therapeutics The Clinical Use of Drug. Lippincott Williams and Wilkins, NewYork, 2005. 23.5-23.7. 4. Taylor C, Carol Lillis, and Priscilla Le Monc. Fundamentals of Nursing. The Art and Science of Nursing Care J.B.Lippincott Company, USA, 1998, 911. 5. Gelchrist.B., Catherine M.Robertson, Christine Webb and Stephen Wright. The Text book of Adult Nursing, Chapman and Hall, London, 1992, 243. 6. Tortora, G.J and Nicholas P.A.Principles of Anatomy and Physiology. 4th Edition, Harper and Row Publishers, New York, 1984, 560. Read More