6.10 Respiratory Viral Infections

Overview

Influenza, COVID-19, and respiratory syncytial virus (RSV) represent three significant respiratory illnesses that have garnered global attention due to their contagious nature and potential for severe health complications. Influenza, commonly known as the flu, is caused by influenza viruses that primarily infect the respiratory tract, leading to symptoms such as fever, cough, sore throat, body aches, and fatigue. COVID-19, caused by the novel coronavirus SARS-CoV-2, emerged as a global pandemic in late 2019, causing a wide spectrum of symptoms, ranging from mild respiratory distress to severe pneumonia and organ failure. RSV, a common cause of respiratory infections in infants and young children, is characterized by symptoms similar to the common cold, including coughing, sneezing, and fever.^[1]

Pathophysiology

Each pathogen has distinct pathophysiological mechanisms, but they share a commonality in targeting the respiratory system, often leading to inflammation, tissue damage, and compromised lung function. Understanding the pathophysiology behind these illnesses is crucial for developing effective preventive measures and treatment strategies to mitigate their impact on public health.

Influenza viruses primarily target epithelial cells lining the respiratory tract. The virus enters the body through inhalation of respiratory droplets or contact with contaminated surfaces. Once inside the respiratory tract, the virus attaches to specific receptors on the surface of epithelial cells, facilitating viral entry and replication. This process triggers an inflammatory response characterized by the release of cytokines and chemokines, which recruit immune cells to the site of infection.^[2]

COVID-19 is caused by the novel coronavirus SARS-CoV-2. Similar to influenza, SARS-CoV-2 enters the body through the respiratory tract via inhalation or contact with contaminated surfaces. The virus primarily targets cells expressing angiotensin-converting enzyme 2 (ACE2) receptors, which are abundant in the respiratory epithelium. Upon infection, SARS-CoV-2 attacks host cellular machinery to replicate, leading to the release of viral particles and cell damage. This triggers a dysregulated immune response characterized by the production of pro-inflammatory cytokines and chemokines, often referred to as a cytokine storm. The resulting inflammation and immune dysregulation contribute to the wide spectrum of symptoms observed in COVID-19, ranging from mild respiratory symptoms to severe pneumonia and acute respiratory distress syndrome (ARDS).^[3]

Respiratory syncytial virus (RSV) primarily infects the respiratory epithelium, particularly in the lower airways. The virus enters the body through inhalation of respiratory secretions or contact with contaminated surfaces. RSV infects ciliated epithelial cells, leading to cell fusion and the formation of multinucleated syncytia, a hallmark of RSV infection. This process disrupts the integrity of the respiratory epithelium and impairs mucociliary clearance, leading to airway obstruction and inflammation. RSV infection triggers an immune response characterized by the recruitment of inflammatory cells such as neutrophils, macrophages, and T cells to the site of infection. The resulting inflammation and mucus production contribute to airway narrowing, respiratory distress, and symptoms such as coughing, wheezing, and difficulty breathing.^[4]

Rhinoviruses are the most common cause of the common cold and are responsible for a large proportion of upper respiratory tract infections worldwide. Like the other mentioned pathogens, rhinoviruses primarily infect the respiratory tract, leading to symptoms such as nasal congestion, runny nose, sneezing, sore throat, and coughing. While rhinovirus infections are usually mild and self-limiting, they can occasionally lead to more severe respiratory complications, especially in individuals with weakened immune systems or underlying health conditions. Despite their prevalence and impact on public health, there are currently no specific antiviral treatments available for rhinovirus infections, highlighting the importance of preventive measures such as hand hygiene and respiratory etiquette in reducing transmission. Including rhinoviruses in discussions of respiratory viral alterations emphasizes the diverse range of pathogens that can affect the respiratory system and underscores the need for comprehensive strategies to address respiratory illnesses on a global scale.^[5]

Assessment

Please review the following Table 6.10a for a list of signs and symptoms of influenza, COVID-19, RSV, and rhinoviruses.

Table 6.10a. Signs and Symptoms of Influenza, COIVD-19, RSV, and Rhinoviruses^{[6],[7],[8],[9]}

Diagnostic Tests

Diagnostic tests play a crucial role in identifying respiratory viral infections, guiding treatment, and implementing appropriate infection control measures. Common diagnostic tests for respiratory viruses focus on the identification of specific viral pathogens. Examples of testing include the following:

Influenza:

• Rapid Influenza Diagnostic Tests (RIDTs): These tests detect influenza viral antigens in respiratory specimens (e.g., nasal swabs) within minutes. While rapid and convenient, they may have lower sensitivity compared to other tests.
• Reverse Transcription Polymerase Chain Reaction (RT-PCR): RT-PCR tests detect viral RNA and are considered the gold standard for diagnosing influenza. They offer high sensitivity and specificity and can differentiate between influenza virus types and subtypes.
• Viral Culture: This method involves growing influenza viruses in cell cultures from respiratory specimens. While less commonly used due to longer turnaround times, viral culture allows for virus isolation and further characterization.^[10]

COVID-19:

• RT-PCR Tests: Similar to influenza, RT-PCR tests are the primary method for diagnosing COVID-19. They detect the presence of SARS-CoV-2 viral RNA in respiratory specimens (e.g., nasopharyngeal swabs, sputum).
• Antigen Tests: Rapid antigen tests detect specific proteins (antigens) from the SARS-CoV-2 virus. While generally less sensitive than RT-PCR, antigen tests provide quicker results and can be useful for rapid screening.
• Antibody Tests: Serological tests detect antibodies produced by the immune system in response to SARS-CoV-2 infection. These tests can indicate past infection but are not typically used for diagnosing active COVID-19 cases.^[11]

Respiratory Syncytial Virus (RSV):

• RT-PCR Tests: Similar to influenza and COVID-19, RT-PCR tests can detect RSV viral RNA in respiratory specimens. These tests are highly sensitive and specific for diagnosing RSV infections.
• Direct Fluorescent Antibody (DFA) Test: DFA tests use fluorescently labeled antibodies to detect RSV antigens in respiratory specimens. While less commonly used than RT-PCR, DFA tests provide rapid results and can be useful in certain settings.^[12]

Rhinoviruses:

• RT-PCR Tests: RT-PCR tests can also detect rhinovirus RNA in respiratory specimens. These tests offer high sensitivity and specificity for diagnosing rhinovirus infections.
• Viral Culture: Similar to influenza, rhinoviruses can be cultured from respiratory specimens in cell cultures. While less commonly used, viral culture allows for virus isolation and further characterization.^[13]

Nursing Diagnoses

Nursing care for clients with respiratory viruses focuses on promoting client well-being and recovery. Common nursing diagnoses for clients with respiratory viruses include the following^[14]:

• Ineffective Airway Clearance
• Impaired Gas Exchange
• Altered Breathing Pattern
• Risk for Social Isolation

Outcome Identification

Outcome identification includes setting short- and long-term goals and creating expected outcome statements customized for the client’s specific needs. Expected outcomes are statements of measurable action for the client within a specific time frame that are responsive to nursing interventions.

• The client will maintain patent airway as evidenced by clear lung sounds and absence of audible secretions within 24 hours.
• The client will maintain adequate oxygenation as evidenced by stable oxygen saturation levels (SpO2 > 92%) on room air.
• The client will demonstrate effective use of respiratory techniques (e.g., deep breathing exercises, incentive spirometry) to promote airway clearance within 48 hours.
• The client will identify at least two methods of maintaining social connections while adhering to isolation precautions within 48 hours.

Interventions

Medical Interventions

Medical interventions for respiratory viral infections vary depending on the specific virus and the severity of the illness.

Medication/Antibody Therapy

Antiviral medications provide the cornerstone for the treatment of many respiratory viral disorders. Antiviral drugs like oseltamir (Tamiflu) may be prescribed to reduce the severity and duration of influenza symptoms. Antiviral drugs like remdesivir (Veklury) may be used to treat severe treatment of COVID-19 to inhibit viral replication. With more severe cases of respiratory viral infections, corticosteroids may be prescribed to reduce inflammation, and bronchodilator medications (e.g., albuterol) may be administered to relieve bronchospasm and improve airflow in clients with wheezing or bronchiolitis. If a bacterial co-infection is suspected, clients may be treated with antibiotics. Other common medications such as acetaminophen and ibuprofen may be ordered to help minimize symptoms of fever and alleviate body aches. Nebulized medications such as hypertonic saline and bronchodilators may also be used to help loosen respiratory secretions and improve airway clearance. In cases of COVID-19, monoclonal antibodies may be used to treat high-risk clients and reduce the risk of severe illness and hospitalization.^{[15],[16],[17],[18]}

Supportive Care

Fluid intake helps prevent dehydration, especially in cases of fever and increased respiratory secretions. Supplemental oxygen may be provided to maintain adequate oxygenation. Clients with severe respiratory distress may require more significant respiratory support with continuous positive pressure ventilation, bilevel positive pressure ventilation, or mechanical ventilation to support breathing and improve oxygenation.

Nursing Interventions

Nursing interventions for respiratory viral disorders aim to alleviate symptoms, promote comfort, prevent complications, facilitate recovery, and prevent future illness.

Infection Control Measures

Nurses adhere to standard and transmission-based precautions to prevent the spread of the virus to other clients and health care workers. Clients and caregivers are educated on proper hand hygiene, respiratory hygiene and cough etiquette, and the use of personal protective equipment (PPE).

See Table 6.10b for infection control measures for droplet, contact, and airborne precautions.^[19] 

Table 6.10b. Infection Control Measures

Health Teaching

Nurses provide education on the signs and symptoms of respiratory viral infections, including when to seek medical attention. They teach clients and caregivers about medication management, symptom management strategies, and the importance of adherence to treatment plans. Effective coughing and deep breathing exercise are encouraged to help clear respiratory secretions and maintain airway patency. Fluid intake is encouraged to prevent dehydration, especially in clients with fever or increased respiratory secretions, and clients are taught about the importance of rest and sleep to support the body’s immune response and facilitate recovery.

Immunizations

Nurses encourage clients to remain up-to-date on recommended vaccinations to prevent respiratory illness, including influenza, respiratory syncytial virus (RSV), and COVID vaccines.

Evaluation

During the evaluation stage, nurses determine the effectiveness of nursing interventions for a specific client. The previously identified expected outcomes are reviewed to determine if they were met, partially met, or not met by the time frames indicated. If outcomes are not met or only partially met by the time frame indicated, the nursing care plan is revised. Evaluation should occur every time the nurse implements interventions with a client, reviews updated laboratory or diagnostic test results, or discusses the care plan with other members of the interprofessional team.