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Updated: Aug 20, 2026

Label-free Neutrophil Enrichment from Patient-derived Airway Secretion Using Closed-loop Inertial Microfluidics
Published on: June 7, 2018
Positive end-expiratory pressure above lower inflection point minimizes influx of activated neutrophils into lung
Shelley L Monkman1, Chad C Andersen, Claude Nahmias
1Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
Objectives:
To compare the effects of low vs. high tidal volume (Vt) with three positive end-expiratory pressure (PEEP) strategies on activated neutrophil influx into the lung.
Design:
Prospective, randomized controlled animal study.
Setting:
Animal laboratory in a university hospital.
Subjects:
Newborn piglets.
Interventions:
Surfactant-depleted piglets were randomized in littermate pairs; to PEEP of either 0 (zero end-expiratory pressure [ZEEP]; n = 6), 8 cm H2O (PEEP 8; n = 5), or 1 cm H2O above the lower inflection point (LIP) (PEEP>LIP; n = 6). Within each pair piglets were randomized to a low VT (5-7 mL/kg) or high VT strategy (17-19 mL/kg). After 4 hrs of mechanical ventilation, 18-fluorodeoxyglucose (18FDG) was injected and positron emission tomography scanning was performed.
Measurements And Main Results:
VT and PEEP changes on influx constants of 18FDG were assessed by analysis of variance. A within-litter comparison of Vt was nonsignificant (p = .50). A between-litter comparison, ordered in linear trend rank, from ZEEP, to PEEP 8, to PEEP>LIP, showed a strong effect of PEEP on influx constant (p = .019).
Conclusions:
PEEP set above the LIP on the inspiratory limb of the pressure-volume curve affords a stronger lung protection than VT strategy.
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