Clinical Pulmonary Infection Score (CPIS)

The score explained

The clinical pulmonary infection score evaluates objective data in patients suspected of ventilator-associated pneumonia (VAP) and stratifies risk of positive diagnosis.

The score also helps clinicians determine which patients may benefit from a pulmonary culture testing.

This means that the administration of the score not only facilitates diagnosis but also helps reduce unnecessary tests and antibiotic administration, thus reducing the incidence of misdiagnosed VAP.

There are six individual factors that are assessed when the CPIS is administered, as described in the table below:

Although, fever and extent of oxygenation impairment are reflective of pneumonia symptoms quantitative microbiological evidence still needs to be accounted for.

Oxygenation and blood leukocyte count are the two variables from the score that weight on the mortality from VAP prognosis.

One shortfall of the score was observed in terms of the substantial inter observer variability, which makes it impossible to use in randomized clinical trials.

Result interpretation

Each of the six variables in the score is awarded a number of points, depending on its predictive value and contribution towards the risk of positive diagnosis. The total CPIS varies between 0 and 12, where 0 means normal function with little risk of VAP and 12 means high risk.

The original study introduces a cut-off value at 6 points, where scores below 6 indicate a low risk of pulmonary infection while scores of 6 and above indicate a high likelihood of VAP diagnosis.

About the study

The CPIS is based on a 2004 study by Schurink et al. which aimed to reduce the number of unnecessary quantitative microbiological cultures (from bronchoscopy).

The scores obtained via CPIS were compared with results from quantitative cultures of bronchoalveolar lavage fluid in a cohort of 99 consecutive patients with suspicion of VAP. The cut-off for diagnosis was growth of > or = 10(4) CFU/mL in bronchoalveolar lavage fluid.

Inter-observer reliability was tested between 2 different intensive care unit clinicians for 52 patients from the cohort.

VAP was diagnosed in 69 patients. The cut off value of 6 points showed 83% sensitivity and 17% specificity. The area under the receiver operating characteristic curve was 0.55.

The CPIS was found to have low and limited specificity and sensitivity, compared to the quantitative cultures of bronchoalveolar lavage fluid. Also, the score could not be validated for use in other respiratory conditions like chronic obstructive pulmonary disease or acute lung injury.

VAP medical guidelines

Ventilator-associated pneumonia makes up more than 25% of ICU acquired infections and more than 50% of antibiotic use in the same level of care. VAP has significant associated morbidity and mortality rates.

To this date, there is no gold standard for the diagnosis of this condition and efforts are made to create a standardized method.

The Harborview Medical Center has devised a therapeutic algorithm, the highlights of which are summarized in the following lines.

The clinical suspicion of VAP should be based on:

■ One or more of the following: fever, purulent endotracheal secretions, leukocytosis;

■ x-ray criteria;

■ No introduction of new antimicrobials for more than 72 hours.

Bronchoscopy can be performed on hemodynamically stable patients. The antibiotic therapy choice also depends on whether the patient has been diagnosed early or not and whether they have been hospitalized for more than 4 days.

When the bronchoalveolar lavage reaches less than 104 CFU/mL or brush specimen less than 103 CFU/mL antimicrobial treatment can be stopped.

Original source

Schurink CA, Van Nieuwenhoven CA, Jacobs JA, Rozenberg-Arska M, Joore HC, Buskens E, Hoepelman AI, Bonten MJ. Clinical pulmonary infection score for ventilator-associated pneumonia: accuracy and inter-observer variability. Intensive Care Med. 2004; 30(2):217-24.

Validation

Fartoukh M, Maitre B, Honoré S, Cerf C, Zahar JR, Brun-Buisson C. Diagnosing pneumonia during mechanical ventilation: the clinical pulmonary infection score revisited. Am J Respir Crit Care Med. 2003; 168(2):173-9.

Other references

1. Shan J, Chen HL, Zhu JH. Diagnostic accuracy of clinical pulmonary infection score for ventilator-associated pneumonia: a meta-analysis. Respir Care. 2011; 56(8):1087-94.

2. Parks NA, Magnotti LJ, Weinberg JA, Zarzaur BL, Schroeppel TJ, Swanson JM, Fabian TC, Croce MA. Use of the clinical pulmonary infection score to guide therapy for ventilator-associated pneumonia risks antibiotic overexposure in patients with trauma. J Trauma Acute Care Surg. 2012; 73(1):52-8; discussion 58-9.

3. Zilberberg MD, Shorr AF. Ventilator-Associated Pneumonia: The Clinical Pulmonary Infection Score as a Surrogate for Diagnostics and Outcome. Oxford Journals Medicine & Health Clinical Infectious Diseases. 2010; V51, IS 1Pp. S131-S135.