Clinical Physiology. Introduction to the Lungs. Anatomy and Physiology

Case Study
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Introduction to the Lungs
Anatomy and Physiology
The human body comprises various systems from head to foot. The pulmonary system involves organs such as the trachea and two lungs which is accountable for the exchange of gas occurring in the body. These organs in the body are mainly accountable for oxygen gas intake and carbon dioxide expulsion. During inspiration, the air that is inhaled by the body travels either via the oral or nasal cavity. The filtration of air that breathes takes place in the nasal cavity through the mucous produced. Once the air is inhaled, the air from the nasal cavity would then travel towards the pharynx (Hall, 2016).
From the pharynx, it would further travel down to the larynx, which is covered by the epiglottis. As it lies in the pharynx, the epiglottis is a flap of skin that is responsible for ensuring that no foreign bodies will be stuck in the trachea or windpipe. The air would then go towards the trachea from the larynx. Two main bronchi – both right and left – would branch out from the trachea leading directly to the lungs. From the primary bronchi, the air moves to the secondary bronchi. From here, it further branches out towards the different lobes of the lungs (Verhoeff & Mitchell, 2017).
The right lung consists of three lobes while the left has two lobes. Finally, air would then travel towards the bronchioles which are their final destination. The alveoli, air sacs found in the lungs, are bounded by these bronchioles. In these air sacs, the gas exchange will take place wherein oxygen will be diffused into the surrounding capillaries. Simultaneously, carbon dioxide will also be absorbed from the capillaries which will be excreted through exhalation later on (Verhoeff & Mitchell, 2017).
In the process of inspiration and expiration, specific muscles are utilized by the body as a driving force. Through this, the lungs will be supplied with an adequate amount of air. Located just beneath the lungs is the diaphragm that functions during inspiration. Along with the intercostal muscles, the diaphragm would facilitate the pulling of air towards the lungs, particularly during inhalation. Moreover, during expiration, this muscle also plays a role in the expulsion of carbon dioxide out of the lungs. As these muscles of inspiration contract, the rib cage, as well as the sternum, elevates resulting in decreased pressure of air within the lungs (Verhoeff & Mitchell, 2017).
Additionally, the contraction of the diaphragm – or its downward movement – would result in the increase of the thoracic cavity’s surface area. The lowered air pressure inside the lungs is a result of both of these contractions which allows air to be pulled inside the lungs. In contrary to this, during expiration, the involved muscles – diaphragm and intercostals – relax. Both the sternum and the rib cage will be pushed towards its initial positions, moving the diaphragm back towards the lungs. The process of relaxation results in the increased pressure of air within the lungs which would cause the air to be expelled out of the thoracic cavity (Verhoeff & Mitchell, 2017).
Other muscles that contribute to the process of inspiration include the sternocleidomastoid muscle, the scalenes anterior, middle, and posterior, pectoral major, and upper trapezius. Whereas muscles that contribute to expiration include the abdominal muscles namely the transversus abdominis, rectus abdominis, and both oblique internal and externa (Verhoeff & Mitchell, 2017).
Chronic Obstructive Pulmonary Disease
Chronic Obstructive Pulmonary Disease, also known as COPD, is a disease frequently caused by long-term smoking which leads to difficulty of breathing even during normal activities. Moreover, when combined with a genetic predisposition to malignancies, this often leads to a carcinoma of the lung (Walker, 2018).
It can be classified into two, namely, chronic bronchitis and emphysema. However, the majority of the people who have incurred the disease have a combination of these two (Walker, 2018).
Case Study
Significant Signs and Symptoms
Subjective: History
Several indications are present in the case study which are all evident in the signs and symptoms of the patient. All of these are pointing to a pathology of the lungs. The following are the signs and symptoms, including the risk factors, that are indicative of lung pathology: 1) The patient is a 68 years-old. Conditions affecting the lungs are more common in older age especially because of the chronicity of the utilization of the risk factors such as cigarette smoke. Moreover, the older the age, the more incidences of exacerbations that the patient has incurred (Dotan, So, & Kim, 2019).; 2) Shortness of breath during light to moderate activities are evident as manifested by coughing accompanied by pins and needles that radiate down the left arm of the patient. COPD cases produce these symptoms. Moreover, the radiating pins and needles sensation or numbness is also common in COPD cases, particularly in chronic bronchitis (Zhang, Zheng, Zhang et al., 2018).; 3) The patient noticed that he has been losing appetite and weight, and that he is easily fatigued. Studies have shown that patients suffering from COPD, particularly chronic bronchitis have an increased amount of tumor necrosis factor-alpha, which is a cytokine that represses hunger. This leads to the decreased amount of nutrients taken by the body, resulting in weight loss (Mohammed, 2018).; 4) Easy fatigability may be secondary to the decrease in the oxygenation of blood (Fayazz, 2019).; 5) The patient experiences night sweats and an intermittent inflammation of his throat. However, he attributes this to his recent viral infection.; 6) Night sweats are common in patients with COPD, especially in chronic bronchitis. However, it can also be evident in other lung diseases such as Tuberculosis and pneumonia (Castellana, Grimaldi, Castellana et al., 2019).; 7) Frequent infections can also result secondary to the impaired immune system and lack of nutrition by these patients.; 8) Coughing of sputum is also evident secondary to the increased production of mucus (Dotan, So, & Kim, 2019).
Objective: Clinical examination
The patient appears to be in cardiopulmonary distress with evidence of reduced blood refill as manifested in the > 3 second during the capillary refill test. The use of accessory muscles is also an evidence of cardiopulmonary distress. Moreover, the patient assumes a tripod position which is usually done by the patients to improve breathing and circulation. Furthermore, patchy hair loss on the patient’s forearms are common in patients with chronic bronchitis (>60 years-old) (Booth & Hackett, 2018).
Rapid weight loss is also evident in the patient’s BMI which drastically decreased from 32.2Kgm2 to 28.4Kgm2 in a span of 10 days. Furthermore, cold and clammy digits is an evidence of the lack of oxygenation of blood. This is highly suggestive of nutritional loss that may be secondary to the loss of appetite (Mohammed, 2018).
His high blood pressure may be attributed to the increased intrathoracic lung pressure which results in a decrease in the preload of the heart. Moreover, poor oxygenation also contributes to the probable cardiac muscle ischemia. Thus, increasing the susceptibility of COPD patients to cardiovascular events (Imaizumi, Kario, Eguchi, & Taketomi, 2017).
Diagnostic Tests
Spirometry Results
Spirometry results in patients with COPD can be classified into reversible and irreversible. Under the reversible category, the following are the values for the mild, moderate, severe, and very severe types of COPD in the predicted value of FEV1: >80%, 50-80%, 30-50%, and <30%, respectively. The patient has an abnormal result in FEV1 which is at 2.3L (74% predicted). Thus, the patient is suffering from moderate COPD (Rothnie, Chandan, Goss et al., 2018).
Peak Flow
The normal value for peak flow is at 400-600mL/min. The patient’s peak flow is at 340 mL/min which is indicative of an abnormal finding at the red zone which has a value of 50% of the normal reading for the patient’s height (Criner et al., 2016).
Carbon Monoxide Detector
The following are the normal values for the peak flow: Adults: less than 2.3%, or 0.023. Adult smokers: 2.1% to 4.2%, or 0.021 to 0.042. Adult heavy smokers (more than 2 packs a day): 8% to 9%. The patient has a result of 3 parts per million which is indicative of severe condition (University of Rochester Medical Center, 2020).
Walking Test
According to Ouaalaya et al. (2019), shortness of breath during at activity must be none or at zero-rating. However, the patient scored 7 which is very severe. Moreover, it is accompanied by a decrease in the saturation level of oxygen to 92% whereas the normal levels are at 96-100%.
Blood Biochemistry
The following are the patient’s blood chemistry results: Fasting blood glucose test: 7.2mmol/L, Total blood cholesterol 6.8mmol/, LDL 4.2mmmol HDL 1.0mmol/L, Serum triglycerides 2.4mmol/L. The normal values for these are as follows: 3.9-5.6 mmol/L, 3.88-5.15 mmol/L, <3.36 mmol/L, >1.04 mmol/L, and 2.82 mmol/L, respectively (Farinde, 2019).
The patient has elevated blood glucose, total blood cholesterol, LDL, and serum triglycerides. However, his HDL or the good cholesterol is low (Farinde, 2019).
Electrocardiogram (ECG)
Peaked P waves, absent R waves in some, and low voltages are evident in the patient’s ECG. All of these are indicative of COPD (Burns, 2019).
Differential Diagnoses
Chronic Bronchitis
Chronic bronchitis is a disease of the lung secondary to the prolonged use of cigarette smoke. Moreover, patients also have a family history of having different types of lung diseases, specifically, COPD. There are also occupational hazards that may be implicated in this disease such as working in mines, factories, and other (Lahousse, Seys, Joos et al., 2017).
Its most common signs and symptoms are shortness of breath or difficulty in breathing. Thus, forcing the patient to always assume the tripod position. Dyspnea on exertion can also happen with or without activities. Others include night sweats, coughing of sputum, cyanosis, clubbing of fingers, weight loss, and loss of appetite (Lahousse, Seys, Joos et al., 2017).
Emphysema
This is another type of COPD that can be secondary to exposure to cigarette smoke, toxic gases, biomass fuels, dust, and pollution. Approximately ten to fifteen percent of smokers incur the disease (Pahal, Avula, & Sharma, 2019).
The profoundness of signs and symptoms is mainly dependent on the severity of smoking and the duration of exposure. Moreover, the baseline function is also important. It has been noted that the symptoms start to become evident after twenty years of exposure from the said risk factors (Pahal, Avula, & Sharma, 2019).
Around fourteen million Americans are affected by the disease. Fourteen percent of white male smokers and three percent of white male nonsmokers are part of these fourteen million. Women of American and African-American origins are less affected (Pahal, Avula, & Sharma, 2019).
The incidence is gradually becoming massive secondary to the increasing environmental pollution and the invention of e-cigarettes and other devices similar to cigarette smoke. Moreover, genetic factors also contribute to the possible airflow limitation experienced by these patients (Pahal, Avula, & Sharma, 2019).
Emphysema is highly prevalent in coal workers and it can also co-exist with coal worker’s pneumoconiosis independent of smoking position (Pahal, Avula, & Sharma, 2019).
Signs and symptoms include shortness of breath, progressive dyspnea, coughing with sputum, dyspnea on exertion, cachexia, using of accessory muscles for breathing, pursed-lip breathing, increased lung resonance on exhalation, and sometimes, with accompanying wheezing. Clubbing of fingers and cyanosis is atypical of emphysema unlike in chronic bronchitis (Pahal, Avula, & Sharma, 2019).
The results of spirometry are the same with chronic bronchitis. Additional information can also be gathered through genetic testing of alpha-1 antitrypsin when the patient is young. Moreover, a chest x-ray may be helpful in the diagnosis of severe emphysema cases and this may present as over-inflation of the lungs (Pahal, Avula, & Sharma, 2019).
Pneumonia
Community-acquired pneumonia was also considered since it also presents with respiratory manifestations somewhat similar to Tuberculosis. The common risk factors include smoking, HIV infection, and other lung problems such as COPD. The typical manifestations are productive coughing for more than 2 weeks, chest pain, shortness of breath, and nausea and vomiting less commonly CITATION Ced20 \l 1033 (Cedars-Sinai, 2020). However, it may be caused by bacterial etiologic agents such as Haemophilus influenza and Mycoplasma pneumonia as well as viruses such as the Adenovirus and Influenza virus CITATION Set19 \l 1033 (Sethi, 2019).
Tuberculosis
Non-tuberculous mycobacteria was considered because it has the same manifestations with Tuberculosis. The common risk factors include comorbidities such as HIV, Bronchiectasis, cystic fibrosis. The typical manifestations are persistent cough, fatigue, weight loss, night sweats, and occasionally dyspnea and hemoptysis. However, it is caused by different Mycobacterium spp. On the other hand, tuberculosis is caused by Mycobacterium tuberculosis. Also, these infections are not transmitted from one person to another, but are acquired from the environment and they do not usually cause illness CITATION Nat18 \l 1033 (National Organization for Rare Disorders, 2018). Thus, it was considered the least differential for this case.
Lung Cancer
Lung cancer is the most common type of cancer worldwide and it also presents with signs and symptoms similar to TB. The common risk factors include smoking, exposure to asbestos and carcinogens as well as a family history of lung cancer. The typical signs and symptoms include persistent dry or productive coughing the do not go away, hemoptysis, chest pain, unintentional weight loss, fever, night sweats, and fatigue. This is often misdiagnosed as pulmonary tuberculosis. Tuberculosis mimics lung cancer due to the presence of pulmonary infiltrates and mediastinal lymphadenopathy CITATION Ham15 \l 1033 (Hammen, 2015).
Small Cell Lung Carcinoma
Small cell lung cancer or SCLC, is also referred as oat cell carcinoma. This malignant tumor emerges from peribronchial locations such as the epithelial cells that line the lower respiratory tract, infiltrating the bronchial mucosa (Cascone, Gold, Glisson, 2016).
When the tumor metastasizes, it is usually widespread that occurs early during its course. The common locations where it metastasizes include liver, mediastinal lymph nodes, bones, brain and adrenal glands (Cascone, Gold, Glisson, 2016).
The signs and symptoms that are commonly observed in this condition include cough, shortness of breath, weight loss, bone pain, fatigue, as well as neurologic dysfunction. Th...