Model-based PEEP optimisation in mechanical ventilationReport as inadecuate

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BioMedical Engineering OnLine

, 10:111

First Online: 23 December 2011Received: 07 November 2011Accepted: 23 December 2011


BackgroundAcute Respiratory Distress Syndrome ARDS patients require mechanical ventilation MV for breathing support. Patient-specific PEEP is encouraged for treating different patients but there is no well established method in optimal PEEP selection.

MethodsA study of 10 patients diagnosed with ALI-ARDS whom underwent recruitment manoeuvre is carried out. Airway pressure and flow data are used to identify patient-specific constant lung elastance Elung and time-variant dynamic lung elastance Edrs at each PEEP level increments of 5cmH2O, for a single compartment linear lung model using integral-based methods. Optimal PEEP is estimated using Elung versus PEEP, Edrs -Pressure curve and Edrs Area at minimum elastance maximum compliance and the inflection of the curves diminishing return. Results are compared to clinically selected PEEP values. The trials and use of the data were approved by the New Zealand South Island Regional Ethics Committee.

ResultsMedian absolute percentage fitting error to the data when estimating time-variant Edrs is 0.9% IQR = 0.5-2.4 and 5.6% IQR: 1.8-11.3 when estimating constant Elung . Both Elung and Edrs decrease with PEEP to a minimum, before rising, and indicating potential over-inflation. Median Edrs over all patients across all PEEP values was 32.2 cmH2O-l IQR: 26.1-46.6, reflecting the heterogeneity of ALI-ARDS patients, and their response to PEEP, that complicates standard approaches to PEEP selection. All Edrs -Pressure curves have a clear inflection point before minimum Edrs , making PEEP selection straightforward. Model-based selected PEEP using the proposed metrics were higher than clinically selected values in 7-10 cases.

ConclusionContinuous monitoring of the patient-specific Elung and Edrs and minimally invasive PEEP titration provide a unique, patient-specific and physiologically relevant metric to optimize PEEP selection with minimal disruption of MV therapy.

KeywordsARDS ALI Elastance Compliance PEEP Critical care Mechanical Ventilation 6 List of AbbreviationsALIAcute lung injury

APEAbsolute percentage error

ARDSAcute respiratory distress syndrome

COPDChronic Obstructive Pulmonary Disease

ElungPatient-specific constant lung elastance

EdrsPatient-specific dynamic lung elastance

FiO2Fraction of Inspired Oxygen

ICUIntensive care unit

IQRInterquartile Range

MVMechanical ventilation

PawAirway pressure

PtpTranspulmonary pressure

PEEPPositive end expiratory pressure

PF RatioPaO2-FiO2

P0Offset pressure


RMRecruitment manoeuvre


SIMVSynchronized intermittent mandatory ventilation



VILIVentilation induced lung injury

VtTidal volume

WOBWork of Breathing

WOBEWork to overcome respiratory system elastance

WOBRWork to overcome airway resistance


Electronic supplementary materialThe online version of this article doi:10.1186-1475-925X-10-111 contains supplementary material, which is available to authorized users.

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Author: Yeong Shiong Chiew - J Geoffrey Chase - Geoffrey M Shaw - Ashwath Sundaresan - Thomas Desaive


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