Analysis of different levels of positive end-expiratory pressure during lung retrieval for transplantation: an experimental study

Abstract

Atelectasis and inadequate oxygenation in lung donors is a common problem during the retrieval of these organs. Nevertheless, the use of high positive end-expiratory pressure (PEEP) is not habitual during procedures of lung retrieval. Twenty-one Sprague-Dawley male consanguineous rats were used in the study. The animals were divided into 3 groups according to the level of PEEP used: low (2 cmH 2 O), moderate (5 cmH 2 O), and high (10 cmH 2 O). Animals were ventilated with a tidal volume of 6 mL/kg. Before lung removal, the lungs were inspected for the presence of atelectasis. When atelectasis was detected, alveolar recruitment maneuvers were performed. Blood gasometric analysis was performed immediately. Finally, the lungs were retrieved, weighed, and submitted to histological analysis. The animals submitted to higher PEEP showed higher levels of oxygenation with the same tidal volumes PO 2 =262.14 (PEEP 2), 382.4 (PEEP 5), and 477.0 (PEEP 10). The occurrence of atelectasis was rare in animals with a PEEP of 10 cmH 2 O, which therefore required less frequent recruitment maneuvers (need for recruitment: PEEP 2=100%, PEEP 5 =100%, and PEEP 10=14.3%). There was no change in hemodynamic stability, occurrence of pulmonary edema, or other histological injuries with the use of high PEEP. The use of high PEEP (10 cmH 2 O) was feasible and probably a beneficial strategy for the prevention of atelectasis and the optimization of oxygenation during lung retrieval. Clinical studies should be performed to confirm this hypothesis.

A structured narrative review of clinical and experimental studies of the use of different positive end‐expiratory pressure levels during thoracic surgery

“…It was found that 10 cmH 2 O PEEP group was pertinent to improving oxygenation and hemodynamics as well as reducing the incidence of atelectasis of rats. 88 The findings of Michelet et al were consistent with it by analyzing the arterial blood gas of pigs at different levels of PEEP during one lung ventilation. 13 , 89 In addition, they found 10 cmH 2 O PEEP would reduce ventricular preload and cardiac output.…”

“…Sacramento EMF et al applied 2, 5, and 10 cmH 2 O PEEP respectively to Sprague–Dawley male rats during lung transplantation. It was found that 10 cmH 2 O PEEP group was pertinent to improving oxygenation and hemodynamics as well as reducing the incidence of atelectasis of rats 88 . The findings of Michelet et al were consistent with it by analyzing the arterial blood gas of pigs at different levels of PEEP during one lung ventilation 13,89 .…”