INTRODUCTION:

The lungs are paired elastic structures located in the right and left sides of the thoracic cavity.

The trachea conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles) and also the bronchioles eventually end in clusters of microscopic air sacs called alveoli. The lungs are covered by a membrane called the pleura.
The main function of the lungs is that the strategy of gas exchange called respiration (or breathing). In respiration, oxygen from incoming air enters the blood, and CO2, a waste gas from the metabolism, leaves the blood. A reduced lung function means the ability of lungs to exchange gases is reduced.¹ There are several types of lung function tests to evaluate the physiologic processes of the respiratory system.

Pulmonary Function Test:

Lung function tests, also called as pulmonary function tests, or PFTs, are a bunch of tests that measure physiologic abnormalities of lungs include obstruction to airflow, restriction of lung size, and reduce in transfer of gas across the alveolar–capillary membrane.²

There are several differing kinds of pulmonary function tests which may be accustomed provide information about certain respiratory conditions.

· Spirometry may be a test that involves the patient breathing as forcefully as possible into a tube that's connected to a machine, which measures the quantity and rate of the air.

· Body plethysmography may be a test that measures the degree of the air within the lungs, both when a personal inhales deeply and after exhalation.

· Lung diffusion capacity is also a test that measures the efficiency of oxygen transfer from the lungs into the bloodstream.

· Blood oxygen tests, like pulse oximetry and blood gas test, are accustomed measure the concentration of oxygen present within the blood.

· The exercise assay is utilized to measure the function of the respiratory and system in response to controlled exercise.²

Spirometry:

Spirometry is that the term given to the essential lung function tests that measure the air that's expired and inspired. There are three basic related measurements: volume, time and flow. Spirometry is objective, noninvasive, sensitive to early change and reproducible. With the availableness of portable meters, it's applied almost anywhere and, with the proper training, it is often performed by anybody. It's performed to detect the presence or absence of lung disease, quantify lung impairment, monitor the results of occupational/environmental exposures and determine the implications of medicines.³

Indications:

Spirometry is used to

· Establish baseline lung function,

· Dyspnea,

· Detect pulmonary disease,

· Monitor effects of therapies to treat respiratory illness,

· Evaluate respiratory impairment or disability,

· Evaluate operative risk, and

· Perform surveillance for occupational-related lung disease.

· Use in research and clinical trials and epidemiological surveys.⁴

Contraindications:

· Aneurysm

· Haemoptysis of unknown origin

· Pneumothorax

· Unstable cardiovascular status, recent MI or embolism

· Acute disorders affecting test performance, like nausea or vomiting

· Recent thoracic or abdominal surgical procedures

· Eye surgery

· Pleural Effusion

· Post-MI.^3,5,6

Patient Positioning:

Correct measurement posture is as follows:

· Upright sitting: there is a difference within the number of air the patient can exhale from a sitting position compared to a standing position as long as they're sitting up straight and there aren't any restrictions⁸and standing position is more better than supine lying.⁸

· Feet flat on the bottom with legs uncrossed: no use of abdominal muscles for leg position.

· Loosen tight-fitting clothing

· Dentures normally left in: it is best to possess some structure to the mouth area unless dentures are very loose.

· Use a chair with arms: when exhaling maximally, patients can become light-headed and possibly sway or faint.

· Within the hospital setting, it's visiting be impossible for your patient to sit down in an exceedingly chair, therefore, the position of the patient (usually supine) should be the identical and documented for future testing.³

Preparation of The Patient for Spirometry:

Patients should find out about spirometry to assist adequate preparation for the test and to enable the patient to present consent. Many variables may affect the test - before it, the patient should avoid:

· Smoking for 24 hours;

· Drinking alcohol for a minimum of 4 hours;

· Vigorous exercise for a minimum of 30 minutes;

· Wearing any tight clothing;

· Eating an oversized meal for a minimum of two hours;

· Taking short-acting bronchodilators for four hours;

· Taking long-acting beta-2-agonist inhalers for 12 hours;

· Taking slow-release medicines that affect respiratory function, and theophylline-based drugs for 24 hours .⁹

Technique:

The patient must place the mouthpiece in their mouth, then the technician must confirm that there are not any leaks, and thus the patient isn't obstructing the mouthpiece. The procedure is run as follows:

1. The patient must breathe the utmost amount air as they'll with an intermission lasting for fewer than 1s at the complete lung capacity.

2. The mouthpiece is placed just inside the mouth between the teeth, soon after the deep inhalation. The lips should be sealed tightly round the mouthpiece to forestall air leakage. Exhalation should last a minimum of 6 seconds, or as long as advised by the trainer. If only the forced expiratory volume is to be measured, the patient must insert the mouthpiece after performing step 1 and must not breathe from the tube.

3. If any of the maneuvers are incorrectly performed, the technician must stop the patient so on avoid fatigue and re-explain the procedure to the patient.

4. The procedure is repeated in intervals separated by 1 minute until two matching, and acceptable results are acquired.^10,11

Measurements used in Spirometry:

Forced expiratory volume (FEV) gives a measurement of the quantity of air exhaled during a given time - often 0.5, 1, 2, 3, 4 or maybe 6 seconds. At 1s, this is often mentioned as FEV1. On average, a healthy person can exhale quite 80 per cent of the air within the first second. Readings of FEV1 are often wont to classify lung disease in comparison with predicted values for age, sex, height and ethnic origin (British Thoracic Society, 1997):

· Mild: FEV1 = 60-79 percent;

· Moderate: FEV1 = 40-59 percent;

· Severe: FEV1 < 40 percent.

Vital capacity (VC) is another useful measure in determining patients’ lung status. Forced capacity (FVC) represents the entire amount of air exhaled at force from a maximum inhalation (total lung capacity) to maximum exhalation (residual volume), measured against the clock. Relaxed capacity (VC) is that the volume from maximal inspiration to maximal expiration performed slowly, and not measured against the time.

The ratio FEV1/FVC (the amount of air exhaled at one second compared with the entire volume of either the FVC or VC, whichever is that the greater) is usually expressed as FEV1% and can be used to distinguish between restrictive disease, for example, pulmonary fibrosis; and obstructive disease, for example, asthma (Fig 1).

A restrictive pattern affects lung expansion and is characterised by a reduced FEV1, a reduced FVC and a high FEV1/FVC ratio. An obstructive pattern is one which affects the speed at which air are often expelled from the lungs and is characterised by a reduced FEV1, normal FVC and a low FEV1/FVC ratio.¹⁰

Complications:

The complications of spirometry are limited and can render the procedure as inaccurate or ineffective once they occur. They include:

· Respiratory alkalosis as a result of hyperventilation

· Hypoxemia during a patient whose oxygen therapy has been interrupted

· Chest pain

· Fatigue

· Paroxysmal coughing

· Bronchospasm

· Dizziness

· Urinary incontinence

· Increased intracranial pressure

· Syncopal symptoms.^10,11,12,

Summary:

Spirometry is one of the lung function test and a useful, non invasive test for detecting early change in lungs and provides physiological confirmation for diagnoses. When performed correctly, it can be used to assess disease progression and response to therapy. With the introduction of portable meters, it can be performed anywhere and by anyone with good training.

REFERENCE:

1. Kochuthresiamma Thomas. Medical Surgical Nursing. First edition. Volume-1. Jaypee; 2018:106-110

2. Smith, Yolanda. "What is Pulmonary Function Testing?". News-Medical. 2021 September 29. Available from https://www.news-medical.net/health/What-is-Pulmonary-Function-Testing.aspx.

3. V.C. Moore. Spirometry: step by step. Breathe. 2012 March; 8(3)232-240

4. Kevin McCarthy. Pulmonary Function Testing.Medscape.2020 May 14. Available from:https://emedicine.medscape.com/article/303239-overview

5. Ranu, H., Wilde, M., Madden, B. Pulmonary Function Tests. The Ulster Medical Journal, 2011; 80(2), 84–90.

6. Cooper BG. An update on contraindications for lung function testing. Thorax. 2011 Aug;66(8):714-23. doi: 10.1136/thx.2010.139881.

7. Patel AK, Thakar HM. Spirometric Values in Sitting, Standing and Supine Position. J Lung Pulm Respir Res. 2015; 2(1): 00026. DOI: 10.15406/jlprr.2015.02.00026

8. Melam G, Buragadda S, Alhusaini A, Alghamdi M, Alghamdi M, Kaushal P. Effect of Different Positions on FVC and FEV1 Measurements of Asthmatic Patients. Journal of physical therapy science.2014; 26(4) 591-593. 10.1589/jpts.26.591.

9. Kath Cooper, Pat Mitchell. Procedure for the assessment of lung function with spirometry. Nursing Times. 2003 June 10; 99(23): 57

10. Monteagudo M, Rodriguez-Blanco T, Parcet J, Peñalver N, Rubio C, Ferrer M, Miravitlles M. Variability in the performing of spirometry and its consequences in the treatment of COPD in primary care. Arch Bronconeumol. 2011 May;47(5):226-33. [PubMed]

11. Townsend MC., Occupational and Environmental Lung Disorders Committee. Spirometry in the occupational health setting--2011 update. J Occup Environ Med. 2011 May;53(5):569-84. [PubMed]

12. Sumner J, Robinson E, Bradshaw L, Lewis L, Warren N, Young C, Fishwick D. Underestimation of spirometry if recommended testing guidance is not followed. Occup Med (Lond). 2018 Mar 27;68(2):126-128. [PubMed]

Received on 30.09.2022 Modified on 12.10.2022

Int. J. Nur. Edu. and Research. 2022; 10(4):392-394.

DOI: 10.52711/2454-2660.2022.00088