ICU infections (Sources: Revision notes) Flashcards
What are the 4 recognised routes for central venous catheter infection?
Migration of skin organisms along the skin tract formed by the catheter - most common route in short term catheters
Contact contamination of the catheter or injection hub by hands or equipment and subsequent intra-luminal migration of pathogen
Haematogenous spread to catheter from a distant site of infection
Contaminated infusate
What is the definition of central line associated blood-stream infection (CLABSI)
Blood stream infection
The presence of a CVC within the 48 hours preceding blood culture
Absence of another apparent source of the bacteraemia
What is the definition of a catheter-related bloodstream infection (CRBSI)?
Blood stream infection
The presence of a CVC within the preceding 48 hours of the blood culture
And either
1. a positive quantitative CVC blood culture, whereby the same organisms is isolated from both the cvc (or CVC tip) and in peripheral blood
or
2. simultaneous quantitative blood cultures with a >5:1 ratio of colony forming units between CVC and peripheral
(CRBSI is more reserved for research studies)
What are the risk factors for CVC-related infections?
Patient - immunocompromised, severity of illness, loss of skin integrity
Duration of insertion - incidence increases with time
Line - femoral have the highest incidence, and subclavian the lowest; catheters impregnanted with antimicrobials or antibiotics are associated with a decrease in catheter - related bacteraemia
Why do we use bundles of care for CVC lines?
In 2006 Provonst et al reported the use of a CVC insertion and care bundle which reduced CLABSI from 7.7 to 1.4 per 1000 CVC days
What measures reduce risk of CVC-line infection?
Hand washing
Full barrier precautions during insertion
Cleaning skin with chlorhexidine/alcohol rather than iodine
Avoiding femoral site. Choose subclavian over jugular
Removing catheters when no longer necessary
Use of a checklist was encouraged
CVC charts implemented
Use ultrasound to insert - decreases complications, results in less skin puncture and decreases infection rate.
Replace catheters inserted in an emergency
Use catheters with the minimum number of ports
Do not routinely replace to prevent infection
Do not remove or replace based on fever alone
Change administration sets regularly
What is ventilator-associated pneumonia?
A nosocomial infection occurring over 48-72 hours post tracheal intubation
Incidence of opt to 27%
Defined as:
Radiological signs - new or progressive and persistent infiltrate, consolidation or cavitation, clinical signs - including fever, leucocytosis or leucopenia and new onset purulent sputum, new or worsening cough or dyspnoea, crackles and bronchial breathing and worsening gas exchange
Microbiological criteria - positive blood culture growth - not related to other source, positive pleural fluid growth, positive bronchoalveolar lavage
How does a VAP occur?
Microaspiration around the cuff, or during intubation
Bacterial biofilm developing within the tracheal tube
Impaired ciliary clearance of mucous
Positive poressure ventilation driving bacteria into the respiratory tree
What are the risk factors for VAP?
High severity of illness Immune suppression Chronic lung disease ARDS Reintubations Increased gastric pH Supine position Enteral nutrition Intra-cuff pressure < 20mmHg
What bugs are most likely in VAP?
Early VAP (within 72 hours of admission) -strep pneumonia -haemophilus influenza -klebsiella pneumoniae -Eschericha coli Later VAP -high incidence of Gram negative bacteria, higher incidence of antibiotic resistance Commonly involve Pseudomonas aeruginosa, MRSA, Acinetobacter, Stenotrophomonas maltophilia
What measures can be take to try and prevent VAP?
Strict hand-washing policy Oral care with chlorhex Head of bed >30 degrees Subglottic suction Maintaining cuff pressure > 20 mmHg Consider silver/antibiotic coated tubes Extubate at earliest opportunity Avoid reintubation Selective oral and digestive decontamination
What is selective decontamination of the digestive tract?
Aimed at reducing VAP incidence
Seeks to prevent endogenous our and exogenous infection
Consists of
-enteral antimicrobials - poorly absorbed agents applied as get to the oropharynx and boluses down the NG e.g. tobramycin
-parenteral antibiotics - a 4 days course of an antipseudomonal
-strict hand hygiene
-regular surveillance from rectum and throat
What is selective oral decontamination?
Admin of poorly absorbed antimicrobials as paste to the mouth - e.g. chlorhex gel
Why is SDD not routine outside of continental Europe?
Concerns regarding possible antimicrobial resistance
External validity of the research has been questioned
Relatively resource intense procedures
