Surveillance for MV Patients in the ICU

Ventilator-Associated Events & Ventilator-associated Respiratory Infections (VARI)

Introduction.

Ventilator-associated respiratory infections (VAP) remain an important condition that is associated with increased mortality (VAP), morbidity (VAP & VAT) and health care costs (VAP & VAT). It is the most frequent intensive care unit (ICU) infection, and it measures quality and safety in care. An increase in stay is why so many efforts have been directed towards its prevention. The actual definition of VAP is highly unspecific, and it is not correlated with history-pathologic findings of pneumonia, independently of microbiologic methods used for its diagnosis. Overall, 50% of episodes remain with the unknown pathogen. Yeast should not be considered a respiratory pathogen.

The U.S Centers for Disease Control and Prevention replaced the VAP surveillance with the ventilator associated-event (VAE) surveillance in January 2013. VAE definitions were designed to overcome some of the major limitations of VAP surveillance. VAE surveillance shifts the focus to pneumonia and a syndrome characterized by respiratory worsening while on mechanical ventilation. This approach provides three major advantages: sidesteps the limited accuracy of VAP surveillance definitions, broadens the focus to include additional morbid events beyond just pneumonia, and allows objective surveillance based on objective and measurable parameters. The major disadvantage is that it is not considered a pathogen and is useless for antibiotic administration.

Surveillance programmes

The VAE surveillance programme should enclose the following definitions: ventilator-associated conditions (VAC), infection-related ventilator-associated complications (IVAC): ventilator-associated tracheobronchitis and (probable or possible) pneumonia (VAP). There have been, however, insufficient efforts to identify risk factors for VAEs, which might be a useful target for preventive interventions. Incidence in Europe until nowadays is limited, and there is barely any experience in paediatric ICUs.

Target population.

Patients who are in an ICU of a participating centre and on mechanical ventilation for at least 48 consecutive hours.

Inclusion criteria:

• ICU admission;
• Mechanical ventilation via Endotracheal or tracheostomy.
• Exclusion criteria:

Mechanical ventilation for less than 48 hours. However, episodes within 48h developed as a consequence of an invasive procedure should be considered nosocomial.

Surveillance

Ventilator-associated event surveillance data:

• daily minimum PEEP and FiO2;
• daily minimum and maximum temperature;
• daily minimum and maximum white blood cell count

Whether endotracheal aspirate or BAL obtained:

• gram stain neutrophil count (quantitative or semi-quantitative);
• culture result (organism and quantity using a quantitative or semi-quantitative scale). Thresholds for pathogen identification should be considered similar for VAP or VAT;

antibiotics (yes / no for each agent for each day).

Surveillance Definitions.

VAC

increase in positive end expiratory pressure (PEEP) minimally by ≥3cmH2O or increase in the fraction of inspired oxygen (FiO2) minimally by ≥0, 20 after a period of stability of ≥2 days or improvement period. Improvement defined as a period of ≥2 days in which daily minimum PEEP or FiO2 have decrease.

IVAC

VAC plus leucocytosis (≥12,000 cells/ml) or leucopenia (≤ 4000cells/ml) or fever (≥38ºC) or hypothermia (≤ 36ºC) and the beginning of a new antibiotic during ≥ 4days.

VAT (Ventilator-associated trachea-bronchitis)

the presence of purulent respiratory secretions, increased inflammation (fever, WBC count or CRP), but the absence of new pulmonary opacities at CXR.

Possible pneumonia: IVAC plus purulent secretions or growth of a pathogenic microorganism on an endotracheal aspiration (EA) or a bronchoalveolar lavage (BAL) culture. (Excluding normal oropharyngeal flora, Candida spp, or non-specified yeast, coagulase-negative Staphylococcus and Enterococcus spp). Purulent secretions are tracheal, bronchial or lung secretions containing>25 neutrophils and <10 squamous epithelial cells by field.

Probable pneumonia: IVAC plus purulent secretions and:

A) Moderate or more growth of a pathogenic microorganism in a culture defined depending on how the sample was collected as follows

ETA ≥ 105 CFU/ml or semiquantitative equivalent;

BAL ≥ 104 CFU/ml or semiquantitative equivalent;

lung tissue: ≥ 104 CFU/g o semiquantitativeequivalent;

protected brush: ≥ 103 CFU/ml o semiquantitative equivalent.

B) Or one of the following without purulent secretions

positive pleural effuse culture (obtained by thoracocentesis or at the moment of placing a chest tube, not from one already placed);

lung-positive histopathology;

positive test for Legionella spp.;

positive test for influenza, respiratory syncytial virus, adenovirus, rhinovirus, human metapneumovirus or coronavirus.

Risk factors surveillance data (to be measured daily):

• sedative choices: continuous, intermittent, or no sedatives;
• muscle relaxants;
• sedation level (Ramsay score);
• spontaneous breathing trials or Spontaneous awakening trials;
• delirium screening;
• fluid balance (in litres);

considerations:

• PIRO score should be measured to stratify severity is patients diagnosed as VAP;
• episodes associated with tracheostomy or intubation should be considered different.

Indicators

VAP / 1,000 ventilator-days (in ET tube)

VAP / 1,000 ventilator-days (in tracheostomy)

VAT / 1,000 ventilator-days (in ET Tube)

VAT / 1,000 ventilator / days (in tracheostomy)

VARI: VAP + VAT

VAC

IVAC

FEM PAGE CONTRIBUTORS 2007

Contributor

Vladimir Prikazsky

Original contribution from

Jordi Rello, Clinical Research& Innovation in Pneumonia and Sepsis (CRIPS) Group Valld' Hebron University, Hospital Barcelona, Spain.