Peep titration based on the open lung approach during one lung ventilation in thoracic surgery: a physiological study

Abstract

BackgroundDuring thoracic surgery in lateral decubitus, one lung ventilation (OLV) may impair respiratory mechanics and gas exchange. We tested a strategy based on an open lung approach (OLA) consisting in lung recruitment immediately followed by a decremental positive-end expiratory pressure (PEEP) titration to the best respiratory system compliance (CRS) and separately quantified the elastic properties of the lung and the chest wall. Our hypothesis was that this approach would improve gas exchange. Further, we were interested in documenting the impact of the OLA on partitioned respiratory system mechanics.MethodsIn thirteen patients undergoing upper left lobectomy we studied lung and chest wall mechanics, transpulmonary pressure (PL), respiratory system and transpulmonary driving pressure (ΔPRS and ΔPL), gas exchange and hemodynamics at two time-points (a) during OLV at zero end-expiratory pressure (OLVpre-OLA) and (b) after the application of the open-lung strategy (OLVpost-OLA).ResultsThe external PEEP selected through the OLA was 6 ± 0.8 cmH2O. As compared to OLVpre-OLA, the PaO2/FiO2 ratio went from 205 ± 73 to 313 ± 86 (p = .05) and CL increased from 56 ± 18 ml/cmH2O to 71 ± 12 ml/cmH2O (p = .0013), without changes in CCW.Both ΔPRS and ΔPL decreased from 9.2 ± 0.4 cmH2O to 6.8 ± 0.6 cmH2O and from 8.1 ± 0.5 cmH2O to 5.7 ± 0.5 cmH2O, (p = .001 and p = .015 vs OLVpre-OLA), respectively. Hemodynamic parameters remained stable throughout the study period.ConclusionsIn our patients, the OLA strategy performed during OLV improved oxygenation and increased CL and had no clinically significant hemodynamic effects. Although our study was not specifically designed to study ΔPRS and ΔPL, we observed a parallel reduction of both after the OLA.Trial registrationTRN: ClinicalTrials.gov, NCT03435523, retrospectively registered, Feb 14 2018.

Physiological effects of two driving pressure-based methods to set positive end-expiratory pressure during one lung ventilation

“…Our data confirm the results of recent studies on the effects of the open lung approach applied during OLV [8]. Rauseo and coworkers found that a PEEP DECREMENTAL strategy was able to decrease transpulmonary driving pressure and to improve oxygenation [8] and Ferrando and co-workers showed that a PEEP DECREMENTAL was able to preserve the improvement in static compliance obtained through a LRM [7]. This could explain our findings of a lower ∆P and of an improvement in oxygenation in the PEEP DECREMENTAL group.…”

“…One major concern is that the PEEP DECREMENTAL approach could critically decrease patient's cardiac output through both a preload and an afterload effect of the LRM needed to recruit the lungs before PEEP titration. However, the hemodynamic impact of the LRM during OLV has been previously shown to be mostly negligible [7,8,25,26]. Some authors advocated the risk that the high amount of energy delivered to the lungs could result in alveolar hyperinflation and thus in a sort of unconscious "harmful" strategy [27,28].…”

“…Park et al found a lower rate of postoperative pulmonary complications (PPC) in patients submitted to an incremental PEEP titration to the lowest ΔP [4]. Conversely, other studies suggest an open lung approach based on a decremental PEEP trial subsequent a lung recruitment manoeuvre (LRM) [7][8][9][10].…”

Mechanical ventilation guidelines in lung lobectomy surgery and the quest to improve outcomes

“…The investigators advocate an open lung approach consisting of an alveolar recruitment maneuver followed by a PEEP adjusted to best respiratory system compliance, the results of which include lower driving pressure, improved lung compliance and a drop in PPCs. These results were mirrored by Rauseo and colleagues in a similar study of PEEP titration in patients undergoing lobectomy (18).…”

Point of Care Ultrasound to Identify Diaphragmatic Dysfunction after Thoracic Surgery

“…As usual care in our department, recruitment maneuvers were used as a rescue therapy in case of intraoperative hypoxemia (defined as Spo 2 less than 90%). 22,23 Balanced crystalloid solutions were administered at a rate of 3 ml • kg −1 • h −1 . Patients were monitored by electrocardiogram, pulse oximetry, end-tidal carbon dioxide, and invasive arterial pressure using a Datex Ohmeda S/5 monitor (Datex-Ohmeda Division, Instrumentarium Corp., Finland).…”