Lung Response to a Higher PEEP During Severe Pneumonia: a CT Study

Effect of a Higher Positive End-expiratory Pressure (PEEP) on Lung Hyperinflation and Collapse in Patients With Severe Pneumonia: a Computed Tomography Study

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT07112976

Enrollment

Registered

2025-08-08

Start date

2022-10-01

Completion date

2024-12-31

Last updated

2025-08-13

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Severe Pneumonia

Keywords

Mechanical ventilation, Positive end-expiratory pressure, Hyperinflation, Recruitment, Computed tomography

Brief summary

At their institution, the investigators routinely assess the individual response of mechanically ventilated patients with acute respiratory failure to higher positive end-expiratory pressure (PEEP) by examining changes in lung aeration through lung computed tomography (CT). They typically obtain two lung CT scans during an end-expiratory hold, one at a PEEP of 10 cmH2O and another at 15 cmH2O. Recruitment and hyperinflation are measured by assessing the decrease in the volume of non-aerated lung regions (with a density greater than -100 HU) and the increase in the volume of hyperinflated lung regions (with a density of less than -900 HU) between the two CT scans. If recruitment exceeds hyperinflation, the response to higher PEEP is considered positive, and medical doctors are encouraged to treat that patient with a higher PEEP. Conversely, if hyperinflation exceeds recruitment, the response is deemed negative, and a higher PEEP is discouraged. This assessment is further complemented by a PEEP test, during which gas exchange (specifically arterial oxygen and carbon dioxide tension) and respiratory system mechanics (including compliance) are evaluated while ventilating with PEEP levels of 10 and 15 cmH2O. In this retrospective analysis, the investigators will focus on patients with severe pneumonia who underwent the two lung CTs as part of their routine clinical practice. They will retrieve data on primary demographic characteristics, significant comorbidities, causes of pneumonia, severity of acute illness, and treatments delivered. Additionally, they will review the results of the quantitative analysis of the lung CT scans taken at 10 and 15 cmH2O, and the PEEP tests. The primary aim of this study is to determine the proportion of patients with net hyperinflation in response to higher PEEP.

Interventions

None listed

Study design

Observational model

COHORT

Time perspective

RETROSPECTIVE

Eligibility

Sex/Gender

ALL

Age

18 Years to No maximum

Healthy volunteers

Inclusion criteria

* adult (≥18 years of age) patients * admitted to ICU from 1/10/2022 to 31/12/2024 * with severe pneumonia * treated with mechanical ventilation * who underwent the two lung CTs at 10 and 15 cmH2O

Exclusion criteria

* pneumothorax * pneumomediastinum * lung CT was obtained with contrast medium to rule out pulmonary embolism

Design outcomes

Primary

Measure	Time frame	Description
Lung response to a higher PEEP	The effects of a higher PEEP will be assessed by comparing the CT scans taken at ICU admission, with a PEEP of 10 or 15 cmH2O, within the same subject. Usually, the interval between the two CT scans is a few minutes.	The primary study objective is to evaluate the effects of higher PEEP with quantitative analysis of lung CT scans in patients with severe pneumonia. We hypothesize that 50% of these patients will exhibit more hyperinflation than recruitment. We measure recruitment and hyperinflation by assessing the change in the volume of non-aerated lung regions (with a density greater than -100 HU) and hyperinflated lung regions (with a density of less than -900 HU) between the two CT scans.

Countries

Italy

Outcome results