Ventilator-Associated Pneumonia - Causes, Symptoms, Diagnosis, and Treatment

Introduction

The individual using a mechanical ventilator develops pneumonia, which results in ventilator-associated pneumonia. It is more common in patients under mechanical ventilation admitted to the intensive care unit (ICU) for at least two days. The infection from the lungs spreads quickly due to malnutrition or a weak immune system. This leads to the destruction of alveoli, or air sacs, interfering with the gaseous exchange.

What Is Ventilator-Associated Pneumonia?

Ventilator-associated pneumonia (VAP) is the most common and deadly nosocomial infection in critical care settings. It develops after 48 hours of endotracheal intubation, but patients may be extubated by then.

What Are the Causes of Ventilator-Associated Pneumonia?

There are various causes of ventilator-associated pneumonia.

They are as follows:

• Mechanical Ventilation - Infectious agents can be aspirated from a mechanical ventilator into the bronchi during intubation. The patient in the intensive care unit or who recently underwent chemotherapy has a reduced defense mechanism against infections. There is an increased risk of infection entering the lungs, which causes ventilator-associated pneumonia.

• Neurologic Disorder - The patient with trauma to the head or severe neurological disorder is admitted to the emergency room for surgery. They are supported by an artificial oxygen supply for breathing. It results in ventilator-associated pneumonia.

• Cardiac Issues - A myocardial infarction occurs due to a bacterial infection. It triggers pneumonia and worsens ventilator-associated pneumonia.

• Lung Diseases - People with preexisting lung diseases like acute respiratory distress syndrome are more susceptible to ventilator-associated pneumonia. The bacteria causing bronchitis can spread to the lungs during positive pressure or mechanical ventilation and cause ventilator-associated pneumonia.

• Bronchoscopy - The infection may enter the lungs during endoscopic procedures like bronchoscopy. Bronchoscopy is used to observe the airways or bronchial tubes. Bacteria affect the lining of the airways and induce pus formation. The multiplication of bacteria is triggered during mechanical ventilation, eventually leading to ventilator-associated pneumonia.

What Are the Symptoms of Ventilator-Associated Pneumonia?

The symptoms of ventilator-associated pneumonia include;

• Temperature - There is a change in body temperature. High temperatures or fevers, occur due to infections. Some individuals experience chills due to ventilator-associated pneumonia.

• Wet Cough - The patient with ventilator-associated pneumonia expels phlegm while coughing.

• Respiratory Rate - The patient has breathlessness with an increased respiratory rate.

• Hypoxemia - The oxygen-carrying capacity of the blood is drastically reduced in an individual with ventilator-associated pneumonia.

• Heart Rate - There is an increase in the heart rate with abnormal heart rhythm.

• Breathing Sound - The patient has abnormal breathing sounds due to shortness of breath. The physician hears them during auscultation with a stethoscope.

• Chest Pain - Some patients have mild chest pain due to pneumonia.

How Is Ventilator-Associated Pneumonia Diagnosed?

The diagnostic procedure for ventilator-associated pneumonia are as follows;

• Chest X-rays - Chest X-rays can examine the abnormal position and irregular shape of the lungs or bronchial tubes. The presence of fluid due to ventilator-associated pneumonia can be detected in the radiographic image. Normal air sacs or alveoli contain air, but it is replaced with fluid or infiltrated during any lung infection or respiratory illness. This is known as consolidation of the lungs. Consolidation is an important diagnosis of pneumonia.

• Blood Test -The white blood cell count increases due to infection in ventilator-associated pneumonia, which is known as leukocytosis.

• Culture Test - Bacterial infection can be revealed during culture tests. The samples are obtained from the pleural fluid, trachea (windpipe), or bronchial tubes (airways). Positive results show the presence of ventilator-associated pneumonia. It is the most specific diagnosis. The commonly found bacteria are Staphylococcus aureus and Pseudomonas aeruginosa.

• Bronchoscopy - The bronchoscope is introduced through openings like the mouth or nose. It is used to detect abnormal bronchial tubes or air passages. The fluid present around the lungs is collected for examination. This surgical procedure is known as bronchoalveolar lavage.

How to Prevent Ventilator-Associated Pneumonia?

Necessary preventive measures should be taken by the medical professional and the patient affected by ventilator-associated pneumonia.

They are as follows:

The medical provider should keep the patient's head position between 30 and 45 degrees to avoid respiratory dysfunction.

• Once the individual starts breathing without mechanical ventilation, the ventilator must be removed immediately.

• During mechanical ventilation, the patient's mouth must be cleaned regularly to prevent the infection from spreading into the body.

• The healthcare provider or caretaker must use antiseptic handwashing before and after operating the mechanical ventilators. It is better to use gloves while handling the ventilators.

• If the same ventilator is used on multiple patients, then care must be taken to disinfect the equipment after every use.

• To avoid infection, noninvasive techniques like continuous positive airway pressure (CPAP) can be used instead of endotracheal intubation.

• The patient must not smoke, as smoking increases the risk of lung infections and ventilator-associated pneumonia.

• The medical provider must change the unstable ventilator circuits and clean the ventilator using sterile water.

What Are the Treatment Measures for Ventilator-Associated Pneumonia?

• The severity of ventilator-associated pneumonia increases in individuals resistant to antimicrobial therapy.

• The antibiotics must be chosen depending on the antibiotic-resistant microbes.

• The antibiotics must be administered within 48 hours of the initial stages of ventilator-associated pneumonia.

• The commonly used antibiotics include Cefepime, Ciprofloxacin, and Levofloxacin.

• Cefepime belongs to the Cephalosporin group. It is effective against Pseudomonas bacteria.

• Ciprofloxacin and Levofloxacin belong to the Fluoroquinolone group. It is used to treat bacterial infections due to Pseudomonas.

• The combination of two drugs is given for severe drug-resistant cases.

• The oral inhalation of Amikacin is used to treat patients with ventilator-associated pneumonia.

• The antibiotic therapy is continued for seven to ten days.

Conclusion

The patient must be reassessed after two or three days of the treatment, and the medications should be changed accordingly. The recovery of patients with ventilator-associated pneumonia depends on underlying systemic diseases. Though ventilator-associated pneumonia is a life-threatening disease, antibiotic therapy can save the patient. There is a high prognosis for patients undergoing antimicrobial treatment in the initial stages of ventilator-associated pneumonia.