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Usefulness of the Recruitment-to-Inflation Ratio and Pulmonary Compliance for Assessing Pulmonary Recruitability in
Jenny Carvalho Badas1, Jaime Guembe1, Celia Novials1
1Anesthesiology Department, Hôpitaux Universitaires de Bruxelles-Site Erasme, Bruxelles, Belgium.
Objective:
To evaluate in cardiac surgery patients the potential for alveolar recruitment at 3 perioperative time points-after intubation, after cardiopulmonary bypass (CPB), and on arrival in the intensive care unit (ICU)-by collecting pulmonary compliance values and calculating the recruitment-to-inflation (R/I) ratio.
Design:
An interventional cohort single-center study conducted in a department of anaesthesiology and critical care and an ICU SETTING: This interventional study was conducted in 41 patients undergoing noncomplex cardiac surgery. Ventilatory mechanics, blood gas analysis, and hemodynamic parameters were measured before, during, and after a lung recruitment maneuver (LRM) (3 minutes at a positive end-expiratory pressure [PEEP] of 12 cmH2O). The R/I ratio was calculated retrospectively at 3 time points.
Participants:
The study included patients scheduled for elective, nonurgent cardiac surgery requiring cardiopulmonary bypass (CPB), including coronary artery bypass grafting (CABG), valve replacement, and valve repair.
Interventions:
R/I ratio measurement.
Measurements And Main Results:
The proportion of recruitable patients (those with an R/I >0.5) decreased over time, from 61% (25 patients) postintubation (IOT), to 29% (12 patients) post-CPB and 17% (7 patients) in the ICU. After recruitment, lung compliance at all 3 time points was significantly higher in recruitable patients (R/I >0.5) compared to nonrecruitable patients (R/I <0.5) (p < 0.01). At all 3 time points, compliance before LRM did not differ significantly between the recruitable and nonrecruitable groups. Of the 123 LRMs performed in 41 patients, 11 (9%) were interrupted because of hemodynamic intolerance (defined as a >20% drop in mean arterial pressure).
Conclusions:
In this study, an R/I ratio >0.5 identified up to 60% of patients as potentially recruitable. This parameter is particularly valuable given that PaO2, partial pressure of oxygen in arterial blood (PaO2), PaO2:fraction of inspired oxygen ratio, and prerecruitment compliance did not predict a positive recruitment response. Further studies are needed to assess the utility of the R/I ratio in individualizing PEEP settings and reducing pulmonary complications in cardiac surgery patients.
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