Introduction
Immunity can be defined as the ability to resist infection and illness. The human body has an immune system, which is an organisation of different machinery meant to prevent and fight infections. When a foreign organism such as a pathogen enters the body, the immune system responds by mounting a response. Two forms of responses are possible: innate and adaptive. The innate immune system precludes the approach, entry and spread of microbes in the body in a nonspecific way (Carton 2019). In contrast, the adaptive immune reaction produces specific responses against the infecting pathogen. The purpose of this paper is to discuss a case study involving a postoperative complication. The initial and ultimate diagnoses together with the pathophysiology of the condition are also explained.
Initial Diagnosis
The patient’s initial diagnoses are urinal tract infection (UTI) and urine retention. A UTI is a bacterial infection in the urinary tract, which spans the kidneys via the ureters, bladder to the outside through the urethra. UTIs are common hospital-acquired infections whose probability of occurrence increases when patients are catheterized during surgery (Ghuman et al. 2018). The symptoms of a UTI include frequent urination, a burning sensation during voiding, pressure in the lower abdomen, and cloudy urine that may contain traces of blood. However, as the infection progresses, symptoms such as lower back pain, fatigue, and fever. The patient in this case study exhibited lower back pain and malaise, which were indicators of infection in the urinary tract. However, she had difficulties passing urine, which indicated urine retention. The treatment of UTIs entails the administration of antibiotics against the causative microorganisms. Therefore, the patient received an initial dose of levofloxacin to treat the infection. On the contrary, urine retention is the inability to pass urine and can be attributed to the body’s reaction to the anaesthesia used during surgical procedures.
Ultimate Diagnosis
If a UTI remains untreated or does not respond to the administered antibiotics, the infection may spread to the kidneys, resulting in more illness and discomfort. It may also cause sepsis. When sepsis is associated with a UTI, the term urosepsis is usually used. The symptoms of urosepsis include pyrexia, lower back pain, extreme fatigue, low production of urine, fast breathing, a fast heart rate (tachycardia), confusion, anxiety, abnormal heart function, abdominal pain, profuse sweating, nausea and fatigue (Makowska et al. 2018). After 48 hours of treatment, Jackie became anxious, confused, tachycardic and showed signs of hypotension. Her condition worsened in the subsequent 36 hours as shown by decreased breathing sounds, reduced urinary flow and high creatinine levels. These symptoms confirm that the final diagnosis was urosepsis.
Pathophysiology
When an infectious pathogen enters the body, the innate immune system mounts an immune response to help the body fight the infection. Normally, macrophages and neutrophils produce small quantities of pro-inflammatory cytokines such as interleukin 1 and tumour necrosis factor (TNF) around the area of the infection. These intermediaries stimulate the production of additional phagocytic leukocytes in the same area. Nonetheless, uninhibited positive feedback machinery can lead to the uncontrolled secretion of these cytokines, leading to a ‘cytokine storm’ or hypercytokinemia. As a result, Systemic Inflammatory Response Syndrome (SIRS) may develop. SIRS may lead to sepsis in the presence of an infection.
In the urinary tract, several soluble substances that are secreted into urine play a role in protection from microbial colonisation. Furthermore, anatomical barriers, for example, hydrated mucous and glycoprotein plaque uroplakins contribute to the defence mechanisms. The urinary tract is also covered by epithelial cells and different immune cells such as are pattern recognition receptors (PRRs) that confer protection. Examples of PRRs are Toll-like receptors 2, 4,5 and 11, which recognise the pathogen promptly and prompt a fast and strong pro-inflammatory immune reaction (Akhavan Sepahi, Hosseini and Akhavan Sepahi 2018). Other cells include neutrophils, macrophages, mast cells, and natural killer cells. These barriers inhibit the entry and establishment of infections by pathogens (Abraham and Miao 2015).
The epithelial cells of the urinary tract act as the first line of defence against pathogens. When an infectious microorganism such as E. coli enters the urinary tract, they produce diverse soluble compounds such as pro-inflammatory cytokines and antibacterial agents. For example, interleukins 1, 6 and 8 are among the first cytokines that are seen in urine after an infection (Ching et al. 2019). They also recruit phagocytes into the infected part of the tract. Epithelial cells produce substances that hamper the growth of bacteria. These substances are generally known as antimicrobial peptides (AMPs) and can also be secreted by recruited neutrophils during the later stages of infection. AMPs can also exert immune-regulatory effects, for instance, escalating the production of cytokines and supporting the infiltration of neutrophils. Studies show that pentraxins are a family of conserved proteins that can also work as soluble PRRs (Erreni et al. 2017; Abraham and Miao 2015). The concentration of pentraxin-related protein 3 (PTX3) found in the urine in the course of a UTI has a direct association with the gravity of symptoms (Erreni et al. 2017). The role of PTX3 is presumed to be the binding of bacterial surfaces to influence complement-mediated destruction and uptake by phagocytes.
Phagocytosis is critical for the activation of many PRRs. Therefore, it is a precondition for the instigation of inflammatory signalling reactions. However, due to the treatment being ineffective, the immune system attempted to salvage the situation by promoting more inflammatory reactions, leading to a cytokine storm that is usually associated with collateral tissue injury. Clinical hallmarks of inflammatory cytokine storms include the dilation of blood vessels, refractory hypotension and death. Therefore, a deregulated innate immune response such as SIRS interferes with the homeostatic functioning of the respiratory, cardiovascular and renal systems (Teijaro 2017).
Renal System
The function of the renal system is to maintain fluid and electrolyte balance by getting rid of excess water from the blood. It also gets rid of soluble waste and bacterial toxins, which helps the body to get rid of infections. Other functions include the maintenance of osmolarity, pH and ion concentrations. The pH of blood is maintained when excess hydrogen ions are excreted into urine followed by the reabsorption of bicarbonate from urine. Renal epithelial cells are surrounded by a dense network of macrophages and dendritic cells, collectively called mononuclear phagocytes. These mononuclear phagocytes are thought to play an important role in maintaining the integrity of tissue microenvironments. Many PRRs, including TLRs, are expressed in renal epithelial cells. In a deregulated immune response, a cytokine storm ensues when these molecules trigger excessive proinflammatory responses. Consequently, there is tissue injury, which impairs the normal functioning of the kidneys leading to reduced urine flow. There is an accumulation of fluid, which in turn affects the fluid and electrolyte balance. The poor working of the renal system as manifested by reduced urination means that more fluid is retained in the body. This results in the accumulation of hydrogen ions in the extracellular fluid, which leads to acidosis. The severity of the condition can be assessed by monitoring renal function through conducting renal function tests such as measurement of the glomerulus filtration rate or determining the albumin to creatinine ratio (Grams et al. 2018).
Cardiovascular System
The cardiovascular system includes blood, the heart and blood vessels. Its purpose is to transport gases, nutrients and other useful molecules throughout the body. Normal homeostasis is maintained when there is a continuous flow of blood to the tissues. In a dysregulated immune response, there are high levels of circulating stress hormones. Therefore, tachycardia happens as a systemic reaction to stress. Its role is to boost cardiac output and delivery of oxygen to tissues. It also signifies hypovolemia and points at the need for intravascular fluid repletion. However, even with adequate fluid repletion, tachycardia may persist in cases of sepsis (Baygin and Kararmaz 2018).
Respiratory System
The key function of the respiratory system is to deliver air into and out of the lungs. This process entails the delivery of oxygen into the lungs and the removal of carbon dioxide from the lungs to the outside environment. The exchange of gases takes place at the capillary level within small air sacs known as alveoli, which are found at the ends of the respiratory tree in the lungs. Low blood pressure from the impaired working of the cardiovascular system causes the build-up of fluid in the alveoli, which reduces the amount of air in the lungs. This occurrence interferes with the removal of carbon dioxide from blood and intake of oxygen and is also experienced during acute respiratory distress syndrome (Thompson, Chambers and Liu 2017). Ultimately, there are high levels of carbon dioxide in blood (hypercapnia) and low levels of oxygen in blood and tissues (hypoxia). The accumulated carbon dioxide dissolves in water to form carbonic acid, which leads to respiratory acidosis.
The Other Important Class of Drugs that was Administered
Vasopressors are an important class of drugs used to treat sepsis. Their function is to maintain proper organ perfusion as well as stopping the advancement of organ dysfunction (Colling, Banton and Beilman 2018). Dopamine and norepinephrine are commonly used vasopressors in the management of sepsis. The patient should also receive intravenous dopamine at an initial dose of 2 to 10 mcg/kg/minute by continuous infusion and a maintenance dose of 2 to 50 mcg/kg/minute. Urinary flow should be monitored during treatment.
Conclusion
Problems of the urinary tract system are common postoperative complications. The ineffective treatment of bacterial infections of the urinary tract leads to the deregulation of the immune system, which may culminate in sepsis. An in-depth understanding of the functioning of the innate immune system and its interactions with various body systems is critical for the proper management of postoperative complications.
References
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