Case Study: Pathophysiology and Pharmacology of Respiratory Infection

This report presents a comprehensive analysis of a case study involving a 32-year-old man, Mr. Roger Wilson, with a history of asthma, who presented with a respiratory infection, bilateral pneumonia, shortness of breath, fever, productive cough, and headaches. The report delves into the pathophysiology of asthma and bilateral pneumonia, exploring the role of bacterial and viral infections in causing airway inflammation and obstruction. It examines the immunological perspective, including the role of IgE antibodies and the release of histamine and prostaglandins in triggering inflammation. The report discusses three relevant signs and symptoms: shortness of breath, chest pain, and tachycardia, linking them to the patient's diagnosis and clinical presentation. It then analyzes the pharmacological interventions, including benzylpenicillin, doxycycline, and salbutamol, detailing their pharmacodynamics and pharmacokinetics and their roles in alleviating symptoms such as shortness of breath, chest pain, and tachycardia. The report also addresses the patient's history of asthma, environmental triggers, and the impact of the respiratory infection on the patient's vital signs and overall health. This analysis provides valuable insights into the management of asthma and respiratory infections.

Running head: PATHOPHYSIOLOGY AND PHARMACOLOGY
PATHOPHYSIOLOGY AND PHARMACOLOGY
Name of the student:
Name of the university:
Author note:

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Pathophysiology and link with the case study:
Asthma has emerged as a leading cause of respiratory illness that impacted more than
thousands of individuals each year. In Australia, approximately 2.7 million population
experienced mild to severe asthma in 2018 which resulted in the increased expenditure of health
care (Tay, Abramson, & Hew 2016). The case study involves a 32-year-old man, Mr Rogar
Wilson with a history of asthma who was complaining regarding shortness of breath, fever, and
productive cough and headache. He was identified with a respiratory infection and his chest Xray
exhibit bilateral pneumonia. Considering the pathophysiology of bilateral pneumonia, due to
bacterial or viral infection, the alveoli’s become inflamed and filled with fluid which resulted in
breathing difficulties. The common causative agents of the bilateral pneumonia are
Streptococcus pneumonia, Haemophilus influenza, Legionella pneumophila and Mycoplasma
pneumonia (Yin et al., 2016). On the other hand, viruses such as Influenza A and B,
coronaviruses and adenoviruses can be the causative agent of pneumonia. The common risk
factors for developing bilateral pneumonia include the history of asthma, weakened immune
system, smoking and presence of lungs or heart disease (Davis et al., 2017). The case
study highlighted that Mr roger has diagnosed with a respiratory tract infection which might be
the reason behind airway inflammation as infection, pollen and tobacco are the environmental
triggers that can induce airway inflammation followed by obstruction of airflow. As discussed by
Teo et al. (2018), a bacterial infection in the lungs negatively impacted mucociliary clearance
and facilitate mucous production in the lungs. The rapid mucous production resulted in
inflammation of the lower airway. The case study suggested that Mr Rogar experienced
productive cough over the past week. At this juncture, it can be said that mucous production
resulted in the obstruction of airway and swelling of airway lining. Moreover, the productive

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mucous contain cellular debris, inflammatory cells like leukocytes and epithelial cells that can
trigger the inflammation and block the air tubes of the patients (Teo et al., 2017). The case study
highlighted that the patient experienced Flu-like symptoms, sore throat and respiratory infection
while converting a warehouse into the gym. The pathophysiology can be explained from the
immunological perspective. Fan et al. (2016), suggested that when antigen or allergen (smoke,
pollen, bacterial and viral particle) detected in the body, the immune system responded to the
detected allergen by secreting IgE antibody that binds to the antigen. The binding of IgE
antibody and antigen resulted in degranulation of immune cells such as basophil and mast cells
(Baxter, Clothier & Perrett, 2018). These cells degranulated to release prostaglandin D2 and
histamines which increase the blood flow. The degranulation also releases facilitate smooth
muscle constriction as well as mucous secretion. The process is known as IgE mediated type I
hypersensitivity. Silver et al. (2018), suggested that patients with asthma often experience
bilateral pneumonia since they are sensitive to the environmental triggers and experience
frequent inflammatory responses followed by shortness of breath. Consequently, the patient
experienced shortness of breath, headaches and a productive cough over the past week. On the
other, persistent difficulties in the breathing, chest pain, cough and fever altered the vital signs of
the patients and subjected the patient to the anxiety and distress. The detailed explanation of the
vital signs of the patient will be explained in details in the following section.
Discussion of three relevant signs and/or symptoms of the patient:
As discussed in the case scenario, a patient diagnosed with a respiratory infection and X-
ray report highlighted bilateral pneumonia which resulted in discomfort. At this juncture, the
three most relevant clinical manifestations exhibited by Mr Roger Wilson are shortness of breath,
chest pain and tachycardia.

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Shortness of breath:
Shortness of breath is considered as one of the most common clinical manifestations
exhibited by the patients experiencing asthma or bilateral pneumonia. In this context, the
difficulty of breathing exhibited by the patient due to respiratory infection and history of asthma
which resulted in the inflammatory response and airway obstruction followed by mucous
production (Benkouiten, Al-Tawfiq, Memish, Albarrak & Gautret, 2019) . The case study
suggested that the patient had a history of asthma and experienced productive cough formation in
the past two weeks, highlighting that productive cough formation might be the contributing
factors behind shortness of breath. The breathlessness further resulted in increased respiratory of
the patient. On admission, his respiratory rate was 31 breaths/minute whereas the normal
respiratory rate is 12 to 24 breaths/minute, indicating that he has an elevated respiratory rate
(Cardona-Morrell et al., 2016). Likewise, the oxygen saturation of the patient was also low
which might be the reason behind shortness of breath. The oxygen saturation of the patient also
dropped to 92% whereas normal oxygen saturation for the healthy individual is 98% (Cardona-
Morrell et al., 2016). The low oxygen saturation is observed when lungs of the patients unable to
inhale oxygen due to the production of mucous and transport to the cells and tissues (Berliner,
Schneider, Welte & Bauersachs, 2016). Consequently, oxygen saturation of the patient decreased
followed by lungs damage and other organ damages. Therefore, the shortness of breath resulted
in distress and anxiety as observed in the case of Mr Rogar.
Chest pain:
Chest pain or pleuritic chest pain characterized by sudden stabbing pain or intense pain in
the chest during inhalation and exhalation. pleuritic chest pain is considered as the most common
clinical manifestation of pneumonia which usually caused by inflammation of the partial pleura.

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However, other etiological factors are also present behind the development of chest pain.
Holland and Holland (2019), suggested that the chest pain in pneumonia usually exhibited due to
muscle strains because of excessive coughing. The chest pain also observed due to inflammation
of the airway lining caused by bacteria infection as observed in this case scenario. When the
chest wall moves during breathing, pleura moves which induced a sense of pain (Nguyen , 2018).
The pain usually worsens during breathing difficulty as breathing difficulty increases inhalation
and exhalation. While chest pain results from a viral infection or bacterial infection in the
respiratory tract, it can be caused by pulmonary embolism where blood clot obstruction hinders
the normal flow of blood into the lungs. Even though the patient described his pain score 2 out of
10, it can increase gradually if remain unresolved. In this context, in order to conduct further
diagnosis, these factors are required to consider for avoiding erroneous diagnosis.
Tachycardia:
The patients with bilateral pneumonia and history asthma frequently exhibit elevated
pulse rate or tachycardia. As discussed by Ashok, Cabalag and Taylor (2017),the patients with
severe breathing difficulties often have low oxygen saturation. The underlying reason is the
mucous production resulted in inflammation of lungs and low oxygen saturation. The inadequate
oxygen saturation in the blood increases the oxygen demand of the body. In order to address the
oxygen demand of the body, the heart pumps harder than the typical capacity to transport the
oxygen to cells and tissues and it increases the heart of the patient as observed in this case study
(Anderson et al, 2019). On admission, the pulse rate of the patient was elevated compared to the
normal pulse rate. The vital sign assessment suggested that pulse rate was 128 beats per minute
whereas the normal pulse rate for the healthy individual is 60 to 100 beats per minute (Cardona-
Morrell et al., 2016). The blood pressure of the patient also reduced due to the tachycardia. The

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vital sign assessment suggested that his blood pressure 100/60 mmHg whereas the normal blood
pressure for the healthy individual is 120/80 mmHg (Cardona-Morrell et al., 2016). Therefore,
proper pharmacological support must be provided for better management of the health
condition.
Three pharmacological drugs and role in reducing symptoms:
The case study suggested that clinical manifestations exhibited by Mr Roger Wilson are
shortness of breath, chest pain and tachycardia. The medical orders suggested that Mr Roger
Wilson was provided with benzylpenicillin intravenously, Doxycycline and Salbutamol via
nebulizer.
Benzylpenicillin 1.2g:
Benzylpenicillin is a narrow-spectrum antibiotic used for treating bacterial infection. It is
usually provided to patients intravenously for reducing bacterial infection during pneumonia as
observed in this case study Due to poor oral absorption, it is intravenously provided to the
patients for addressing the infection.
Pharmacodynamics:
It is a beta-lactam antibiotic used for treating bacterial infections triggered by gram-
positive organisms. Considering the pharmacodynamics of the drug, it specifically binds to
penicillin-binding proteins (PBPs) present in the cell wall of the bacteria. After binding, the drug
inhibits the the bacterial cell wall synthesis (Hand et al., 2019). The cell lysis further mediated by
autolytic enzymes such as autolysins as the drug binds to the autolysin inhibitor. The drug is
resistant against hydrolysis process mediated by a range of different enzymes such as
penicillinases.
Pharmacokinetics:

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The pharmacokinetics can be explained using the ADME principle.
Absorption: In case of intramuscular and subcutaneous injection, it is rapidly absorbed by the
body where initial blood levels are high. While the bioavailability of the intravenous
administration is 100%, the bioavailability of the oral administration is 15 to 30% (Bos et al.,
2018).
The volume of distribution: with the normal renal function, it is
0.53–0.67 L/kg.
Protein binding: approximately 45 to 68% of the drug attached to serum protein, especially
albumin (Bos et al., 2018).
Metabolism:
30% of the drug metabolized into the penicilloic acid and a small amount of 6-aminopenicillins
acid which is observed in the urine of the patient. The small portion is hydroxylated into one or
more activate metabolites (Bos et al., 2018).
Route of elimination: the route of elimination is eliminated by Kidney through urination. Some
of the drugs are eliminated through biliary excretion.
Doxycycline:
It is a tetracycline antibiotic that fights bacteria of the body. In this context, as the patient
was experiencing respiratory infection, Doxycycline was provided to the patient for reducing
respiratory tract infection followed by chest pain and tachycardia.
Pharmacodynamics:
Unlike the previous antibiotic, it is a bacteriostatic antibiotic that inhibits the protein
synthesis of the bacteria by attaching to the 30S ribosomal subunit, especially 16 sRna portion of

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the ribosomal subunit. Therefore, the inhibition further prevents the binding of tRNA to RNA-
30S bacterial ribosomal subunit followed by inhibiting protein synthesis (Hopkins et al., 2016).
Pharmacokinetics:
The pharmacokinetics can be explained using the ADME principle.
Absorption: Rapidly absorbed while orally administrated and highly soluble in nature. The peak
serum level of approximately 2.6 mcg/ml within 2 hours (Zhang et al., 2019).
The volume of distribution: it diffuses readily into the body tissues and body fluid with 0.7
L/kg. The protein binding is approximately less than 90% with the plasma protein.
Metabolism: it is metabolized in the GI tract and liver (Zhang et al., 2019).
Route of elimination: the drug mainly eliminated through the urine as well as faeces as
unchanged drug. Approximately 40% to 60% of dose is eliminated through urine within 92
hours.
Salbutamol:
Salbutamol is a bronchodilator that provided to the patients with pneumonia for reducing
shortness of breath. In this context, since the patient was facing shortness of breath, Salbutamol
via nebulizer was provided for reducing the shortness of breath.
Pharmacodynamics:
Salbutamol is a bronchodilator that reduces airway constriction by opening the passage
of the lungs and facilitate normal airflow. Salbutamol is moderately selective beta (2)-receptor
agonist that facilitate airway smooth muscle relaxation followed by Broncho-dilation of the
patient. At the therapeutic dose, it exhibits actions on beta2- adrenoceptors of bronchial muscle
for stimulating bronchodilation and stimulation (Moore et al., 2019).
Pharmacokinetics:

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Pharmacokinetics can be described by ADME principle.
Absorption: salbutamol display actions on smooth muscle, weakly bound to plasma protein.
The peak plasma absorption is about 3 mg/mL within 2 to 3 hours (Vet et al., 2020).
The volume of distribution: The volume of distribution of salbutamol is 156 +/- 38 L.
Metabolism: considering the metabolism, it is digested in the liver and it convert into
salbutamol 4'-O-sulfate. In a few cases, it undergoes oxidative deamination for acting as a
bronchodilator
Route of elimination: Within 24 hours, roughly 72% of the inhaled dose is excreted in the
urine and 28% of them were unchanged drugs (Moore, Riddell, Joshi, Chan& Mehta, 2017). A
small fraction of it eliminated through feces.

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