Model-based PEEP optimisation in mechanical ventilation

Yeong Shiong Chiew,J Geoffrey Chase,Thomas Desaive,Ashwath Sundaresan,Geoffrey M Shaw

doi:10.1186/1475-925x-10-111

Yeong Shiong Chiew, J Geoffrey Chase + Show 3 more

Open Access

https://doi.org/10.1186/1475-925x-10-111

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Abstract

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.

Highlights

Acute Respiratory Distress Syndrome (ARDS) patients require mechanical ventilation (MV) for breathing support
4.1 Model-based positive end-expiratory pressure (PEEP) Selection Median fitting error for time-variant Edrs in Table 2 is less than 1%, showing that a single compartment lung model can be used for time-varying Edrs estimation
The wide range of patient-specific Edrs across all patients and PEEP shown in Table 2 reflects the heterogeneity of acute lung injury (ALI)/ARDS patient condition and response to PEEP that makes standardising and PEEP selection difficult [26]

Summary

Methods

A 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. The trials and use of the data were approved by the New Zealand South Island Regional Ethics Committee. 2.1 Study Design Ten patients in the Intensive Care Unit (ICU), Christchurch Hospital, New Zealand, diagnosed with ALI or ARDS (PaO2/FiO2 (PF ratio) between 150-300 mmHg), underwent a modified protocol-based recruitment manoeuvre (RM) [17]. The clinical trials and the use of the data were approved by the New Zealand, South Island Regional Ethics Committee.

Results

Discussion

Conclusion