Comparison of approaches used to identify optimal PEEP following lung recruitment using a decremental PEEP titration

The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Comparison of approaches used to identify optimal PEEP following lung recruitment using a decremental PEEP titration

Comparison of approaches used to identify optimal PEEP following lung recruitment using a decremental PEEP titration

Maria Paula Caramez MD, Mohamed Helmy MD, Eriko Miyoshi MD, Daniel Chipman RRT, R. Scott Harris MD, Atul Malhotra MD, Robert M. Kacmarek PhD,RRT.  Massachusetts General Hospital, Brigham and Woman’s Hospital and Harvard Medical School. Boston, Massachusetts.

Background:
The best method of identifying optimum PEEP following a lung recruitment maneuver (RM) is still debated. We compared four different methods of identifying optimum PEEP following a RM using a decremental PEEP trial.

Methods:
After initial ventilation (baseline) with VT 10ml/kg, FIO2 1.0 and PEEP 5 cmH2O, lung injury was induced by bilateral lung lavage in 14 female Dorset sheep, PaO2 £ 100 mmHg at FIO2 1.0 and PEEP 5 cmH2O (Injury). PEEP was then set to 20 cmH2O, a RM performed with PCV (PIP 50 cm H2O), until the PaO2+PaCO2 was > 400 mmHg. Following the RM, PEEP was decreased in 1 cmH2O steps every 10 min until the PEEP was 10 cmH2O. Cardiac output, vascular pressures and arterial blood gases were monitored at each PEEP step. Four different approaches were used to identify the “optimal PEEP” level: 1) The PEEP level below which a 10 % fall from the maximum PaO2+PaCO2 was observed after the RM. 2) The PEEP level below which a 10 % fall from the maximum PaO2 was observed after the RM. 3) The PEEP level associated with the minimum PaCO2 and 4) The PEEP level associated with the maximum dynamic compliance.



Results:
The following optimal PEEP levels were observed a) PaO2= 577 ± 89mmHg, optimal PEEP, 19.21 ± 0.97 cmH2O, b) PaO2 +PaCO2=660 ± 101mmHg, optimal PEEP, 19.29 ± 0.99 cmH2O c), minimal PaCO2 = 43 ± 20mmHg optimal PEEP, 19.5 ± 0.94 cmH2O and d) Compliance = 21 ± 8 L/cmH2O optimal PEEP 18.36 ± 1.78 cmH2O (see figure below).

Conclusions: All four approaches result in nearly identical optimal PEEP. Dynamic compliance is the easiest methods but underestimated optimal PEEP by 1cm/H2O. Funding in part by Maquet.

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Comparison of approaches used to identify optimal PEEP following lung recruitment using a decremental PEEP titration