part i background ventilator associated pneumonia

Part IBACKGROUND

VENTILATOR ASSOCIATED PNEUMONIA

Dr. MOUSTAFA ARAFAASSOSIATE PROF. OF EPIDEMIOLOGY HIGH INSTITUTE OF PUBLIC HEALTH ALEXANDRIA UNIVERSITY E-mailMAHA NAGANURSING SPECIALIST ALEXANDRIA UNIVERSITY STUDENT HOSPITAL E-mail

BACKGROUND Nosocomial infections have been recognized for over a century as a critical problem affecting the quality of health care and a principal source of adverse healthcare outcomes. Patients hospitalized in ICUs are 5 to 10 times more likely to acquire nosocomial infections than other hospital patients.

On the other hand the Nosocomial infections that are preventable , perhaps between 30 and 50 percent , are primarily caused by problems in patient care practices , such as the use and care of urinary catheters , and respiratory therapy equipment , as well as hand washing practices and surgical skill.

DEFINITIONS

NOSOCOMIAL INFECTION :An infection acquired in a patient in a hospital or other healthcare facility in whom it was not present or incubating at the time of admission or the residual of an infection acquired during a previous admission.

DEVICE RELATED NOSOCOMIAL INFECTION A device-associated infection is an infection in a patient with a device (i.e., central line, ventilator, or indwelling urinary catheter) that was in use within the 48-hour period before onset of infection. If the interval since discontinuation of the device is longer than 48 hours, there must be compelling evidence that infection was associated with device use.

RISK FACTORS operative surgeryintravascular and urinary catheterization mechanical ventilation of the respiratory tractOther risk factors include traumatic injuries, burns, age (elderly or neonates), immuno-suppression and existing disease

VENTILATOR ASSOSIATED PNEUMOINA Patients receiving continuous, mechanically assisted ventilation have 6-21 times the risk for acquiring nosocomial pneumonia compared with patients not receiving ventilatory support .

Pneumonia cases account for 15 to 20 % of nosocomial infections but is responsible for 24 % of extra hospital days and 39 % of extra cost . Nosocomial pneumonia is associated with mortality rate up to 50 % in ICUs .

RISK FACTORS * Intubation . *altered levels of consciousness , especially those with nasogastric tubes . *elderly patients . *chronic lung disease . *postoperative patients . *any of the above patients taken H2- blockers or antacid .

CRITERIA FOR DIAGNOSIS

fever. cough.development of purulent sputum, in conjunction with radiologic evidence of a new or progressive pulmonary infiltrate. a suggestive Gram stain, and positive cultures of sputum, tracheal aspirate, pleural fluid, or blood.

MICROBIOLOGY Pneumonias are mostly caused by Legionella sp. Aspergillus sp. influenza virus .

PREVENTION AND CONTROL MEASURES

Most of the risk factors can be prevented and controlled with a little effort and performing some policies in the unit as : - use either prophylactic local application of antimicrobial agent(s) or local bacterial interference . - use Sucralfate, a cytoprotective agent as a substitute for antacids and H-2 blockers.

- Prevent Aspiration of oro-pharyngeal and Gastric Flora by : 1-Placing the patient in a semi-recumbent position. 2-Administering enteral nutrition intermittently in small boluses rather than continuously. 3- Using flexible, small-bore enteral tubes . 4-Placing the enteral tube below the stomach (e.g., in the jejunum).

-Perform hand washing before any procedure , wear gloves .-Proper cleaning and sterilization or disinfection of reusable equipment .-The recommended daily change in ventilator circuits may be extended to greater than or equal to 48 hours.

- Prophylaxis with Systemic anti-microbial agents.- Use of "Kinetic Beds" or Continuous Lateral Rotational Therapy (CLRT) for Immobilized Patients.

SUGGESTED FURTHER READINGSSurveillance of nosocomial infectionsRisk Factors and Outcome of Nosocomial Infections: Results of a Matched Case-control Study of ICU Patients

Guideline for Prevention of Nosocomial PneumoniaThe Attributable Morbidity and Mortality of Ventilator-Associated Pneumonia in the Critically Ill Patient

Nosocomial infections have been recognized for over a century as a critical problem affecting the quality of health care and a principal source of adverse healthcare outcomes. Today, nosocomial infections affect over 2 million patients annually in the United States, at a cost in excess of $4.5 billion. Among all major complications of hospitalization, nosocomial infections account for 50%; the remaining are medication errors, patient falls, and other noninfectious adverse events.

A device-associated infection is not present or incubating at the time of the patients admission to the ICU, but becomes apparent during the ICU stay or within 48 hours after transfer from the ICU to another acute care unit within the hospital. An inpatient ICU is a designated unit where there is appropriate equipment and specialized staff to provide continuous care, according to the particular medical needs of a defined and limited class of critically ill patients. Nosocomial bacterial pneumonia has been difficult to diagnose . Frequently, the criteria for diagnosis are fever, cough, and development of purulent sputum, in conjunction with radiologic evidence of a new or progressive pulmonary infiltrate, a suggestive Gram stain, and positive cultures of sputum, tracheal aspirate, pleural fluid, or blood. Although clinical findings in conjunction with cultures of sputum or tracheal specimens may be sensitive for bacterial pathogens, they are highly nonspecific, especially in patients receiving mechanically assisted ventilation ; conversely, cultures of blood or pleural fluid have very low sensitivity .

The association between colonization of the oropharynx , trachea , or stomach and predisposition to gram-negative bacillary pneumonia prompted efforts to prevent infection by using either prophylactic local application of antimicrobial agent(s) or local bacterial interference . The second method i.e. interference with alpha-hemolytic streptococci has been used successfully to prevent oropharyngeal colonization by aerobic gram-negative bacilli. The administration of antacids and H-2 blockers for prevention of stress bleeding in critically ill, postoperative, and/or mechanically ventilated patients has been associated with gastric bacterial overgrowth . Sucralfate, a cytoprotective agent that has little effect on gastric pH and may have bactericidal properties of its own, has been suggested as a potential substitute for antacids and H-2 blockers.

Aspiration usually occurs in patients who : -Have a depressed level of consciousness.-Have dysphagia resulting from neurologic or esophageal disorders.-Have an endotracheal (nasotracheal or orotracheal), tracheostomal, or enteral (nasogastric or orogastric) tube in place.and/or are receiving enteral feeding . Although prevention of pneumonia in such patients may be difficult, methods that make regurgitation less likely (e.g., placing the patient in a semirecumbent position {i.e., by elevating the head of the bed} may be beneficial .

Initial studies of in-use contamination of mechanical ventilator circuits with humidifiers have indicated that neither the rate of bacterial contamination of inspiratory-phase gas nor the incidence of pneumonia was significantly increased when tubing was changed every 24 hours rather than every 8 or 16 hours. In addition, the incidence of nosocomial pneumonia was not significantly higher when circuits were changed every 48 hours rather than every 24 hours . These findings indicate that the recommended daily change in ventilator circuits may be extended to greater than or equal to 48 hours.- The systemic administration of antimicrobials is commonly used to prevent nosocomial pneumonia, especially for patients who are receiving mechanical ventilation, are postoperative, and/or are critically ill . - Use of kinetic beds, or Continuous Lateral Rotational Therapy (CLRT) , is a maneuver for prevention of pulmonary and other complications resulting from prolonged immobilization or bed rest, such as in patients with acute stroke, critical illness, head injury or traction, blunt chest trauma, and/or mechanically assisted ventilation .