CPIS calculator: the clinical pulmonary infection score (Pugin 1991)

The clinical pulmonary infection score (CPIS) puts six bedside and laboratory findings on a common 0 to 2 scale and adds them, for a total between 0 and 12. This CPIS calculator follows the original Pugin 1991 version: you supply the temperature, white cell count, oxygenation and your own readings of the secretions, chest film and culture, and it returns the points and whether the total is above 6.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

Infection and VTE calculators
Pugin J et al. · 1991
The CPIS formula
Worked examples
Frequently asked questions

What is the clinical pulmonary infection score?

Pugin and colleagues built the score in ventilated patients as a way of summarising, in one number, several signs that point towards infection in the lungs. In their derivation, a CPIS above 6 suggested pneumonia. The calculator reports that split as le_6 or gt_6.

Three of the six domains are measurements (temperature, white cell count, PaO2/FiO2). The other three are judgements the caller makes: how the secretions look, what the chest radiograph shows and what the culture grew. Magent doesn't read films, slides or culture reports.

The CPIS formula

CPIS = temperature points
     + leukocyte points (with bands)
     + tracheal secretion points
     + oxygenation points
     + chest radiograph points
     + culture points

each domain 0, 1 or 2; total 0 to 12

Exact expression the calculator uses:

CPIS = temperature(36.5-38.4→0, 38.5-38.9→1, ≥39 or ≤36→2) + leukocytes(4.0-11.0→0, <4.0 or >11.0→1, +1 if abnormal and bands_ge_50) + tracheal_secretions(none→0, nonpurulent→1, purulent→2) + oxygenation(pf_ratio>240 or ards→0, pf_ratio≤240 and not ards→2) + chest_radiograph(none→0, diffuse→1, localized→2) + culture(none→0, pathogen→1, pathogen_and_gram→2); Pugin 1991; max 12; CPIS>6 suggests pulmonary infection in that derivation

Inputs

Input	Meaning	Values
`temperature_c`	Temperature in °C	30.0 to 45.0
`wbc_k_ul`	White cell count, 10^3/µL	0.01 to 500
`bands_ge_50`	Band forms at 50% or more	true or false
`tracheal_secretions`	Appearance of secretions	none, nonpurulent, purulent
`pf_ratio`	PaO2/FiO2 in mm Hg	20 to 800
`ards`	ARDS present, as judged by the caller	true or false
`chest_radiograph`	Infiltrate on the film	none, diffuse, localized
`culture`	Tracheal aspirate culture	none, pathogen, pathogen_and_gram

How the calculation works

Temperature. 36.5 to 38.4 °C scores 0, 38.5 to 38.9 scores 1, and 39.0 or higher, or 36.0 or lower, scores 2. The bins are one-decimal, so a value between 36.0 and 36.5, or between 38.9 and 39.0, falls in no listed bin and scores 0 in this calculator.
Leukocytes. 4.0 to 11.0 scores 0; below 4.0 or above 11.0 scores 1. Band forms at 50% or more add 1 when the count is already outside 4.0 to 11.0; with a normal count they add nothing.
Secretions. None 0, nonpurulent 1, purulent 2.
Oxygenation. A PaO2/FiO2 above 240 scores 0. At 240 or below it scores 2, unless the caller has marked ARDS, in which case it scores 0.
Chest radiograph. No infiltrate 0, diffuse 1, localized 2.
Culture. None 0, pathogen 1, the same pathogen also seen on Gram stain 2.
Add the six domains and set the band: 6 or less is le_6, 7 or more is gt_6.

Worked examples

These use Magent's own expected values for the calculator. Unless stated, the inputs are the zero baseline: 37.0 °C, WBC 8.0, no bands, no secretions, PaO2/FiO2 300, no ARDS, clear film, no culture growth.

Example 1: the zero baseline

Every domain is in its 0 range.
0 + 0 + 0 + 0 + 0 + 0 = 0.
CPIS 0, band le_6.

Example 2: fever, purulent secretions, a localized infiltrate and a pathogen

Temperature 39.0 °C scores 2.
Purulent secretions score 2.
A localized infiltrate scores 2.
Culture with a pathogen scores 1.
2 + 2 + 2 + 1 = 7.
CPIS 7, band gt_6.

Example 3: WBC 12.0 with bands

WBC 12.0 is above 11.0, so the leukocyte domain scores 1.
Band forms at 50% or more add 1, because the count is abnormal.
1 + 1 = 2.
CPIS 2, band le_6.

History of the CPIS

Pugin and colleagues described the score in 1991, in a study comparing bronchoscopic and "blind" bronchoalveolar lavage in ventilated patients. The score combined clinical, radiographic, physiological and microbiological findings. Later modified versions change some domains; this calculator keeps the 1991 scoring.

When it's used

When a team wants a structured summary of the findings that bear on pneumonia in a ventilated patient, alongside cultures and the clinical picture.

Where it's used

Intensive care units and research on ventilator-associated pneumonia.

Who uses it

Intensivists, critical care nurses, infection specialists and researchers. The calculator adds the domain points.

Limits of the calculation

Half the domains depend on the caller's reading of secretions, films and cultures, so two people can reach different totals for the same patient.
The split at 6 comes from one derivation study. It isn't a rule for confirming or excluding pneumonia, and the calculator doesn't identify pneumonia.
Temperatures in the small gaps between the published bins score 0 here.
The calculator gives no advice about antibiotics.
This page doesn't say what a score means for a particular person.

Clinical decisions belong to a qualified clinician who knows the patient.

SIRS counts signs of a systemic inflammatory response, not lung-specific findings.
Berlin definition of ARDS classifies ARDS from a caller-supplied PaO2/FiO2 and clinical criteria.

Glossary

PaO2/FiO2: arterial oxygen divided by the inspired oxygen fraction, in mm Hg.
Band forms: immature neutrophils.
Tracheal aspirate: secretions suctioned from the airway for culture.
Gram stain: a slide stain used to see bacteria.

Common mistakes

Using the modified CPIS. This is the 1991 version.
Adding the band point with a normal count. Bands add a point when the white cell count is outside 4.0 to 11.0, not when it's normal.
Forgetting the ARDS input. With ARDS marked, a low PaO2/FiO2 scores 0.
Entering the white cell count in cells/µL. It's in thousands per µL.

Source

Pugin J, et al. Diagnosis of ventilator-associated pneumonia by bacteriologic analysis of bronchoscopic and nonbronchoscopic "blind" bronchoalveolar lavage fluid. Am Rev Respir Dis. 1991;143(5 Pt 1):1121-1129. DOI: 10.1164/ajrccm/143.5_Pt_1.1121. PMID: 2024824

Frequently asked questions

How is the CPIS calculated?

Score six domains 0 to 2 each and add them. The maximum is 12.

What does a CPIS above 6 mean?

In the Pugin 1991 derivation, a CPIS above 6 suggested pneumonia. The calculator returns gt_6 for 7 or more; it doesn't confirm infection.

Is this the modified CPIS?

No. It's the original 1991 scoring.

Does the calculator read the chest film?

No. You choose none, diffuse or localized.

Why can a temperature just under 39.0 score 0?

The bins stop at 38.9 and restart at 39.0, so values in between score 0 in this calculator.