Compliance and Dead Space Fraction Indicate an Optimal Level of Positive End-Expiratory Pressure After Recruitment in Anesthetized Patients

Abstract

All variables showed the positive effects of PEEP in conjunction with a recruitment maneuver. Optimal PEEP was 10 cm H2O because at this pressure level the highest compliance value in conjunction with the lowest dead space fraction indicated a maximum amount of effectively expanded alveoli. FRC and Pao2 were insensitive to alveolar over-distension.

Systemic Inflammatory Response During Lung Recruitment Maneuvers in a Newborn Animal Model

“…One of the validated ways of selecting optimum PEEP is the optimum level of PEEP that has been identified as maximum dynamic compliance (Max Cdyn-PEEP). [16,17] This indicates that the RM did not cause lung injury with clinical repercussion as published in a previous work by our research group. [26] The RM was performed for a much longer period of time than conventionally established to assess the impact of the RM and the inflammatory response studied by the quantification of cytokine plasma levels.…”

“…This method has been described in relation to the estimation of open-lung PEEP. [16,17] To detect the occurrence of baro-volutrauma, the flow-time and pressure-time curves of the respirator were analysed, and to detect the presence of pneumothorax and subcutaneous emphysema, a radiography was required when the optimum lung opening was reached. We assessed whether a prolonged RM induced an inflammatory response, the data collected from each piglet were compared to the data gathered at the beginning of the experiment (baseline: MIP 15cmH 2 O, PEEP 0cmH 2 O) and to the results obtained 60 minutes following the onset of the RM (after achieving Optimum lung opening: Max Cdyn-PEEP 2cmH 2 O) (Fig.…”

Calculation of Physiologic Dead Space: Comparison of Ventilator Volumetric Capnography to Measurements by Metabolic Analyzer and Volumetric CO2 Monitor

“…3 The prognostic value of V D /V T has been linked to mortality risk in ARDS [4][5][6][7] and to other important clinical indices. V D /V T is known to correlate with the severity of lung injury, [8][9][10][11][12] can be useful as an indicator of lung recruitment versus overdistention in patients with acute lung injury (ALI) and ARDS, [13][14][15][16][17] may be helpful as a predictor of successful extubation in pediatric 18 and adult patients, 19 and may be useful in diagnosing and assessing the severity of pulmonary embolism. 20,21 SEE THE RELATED EDITORIAL ON PAGE 1258 Simplified bedside calculation of V D /V T requires a measurement of the partial pressure of mean expired CO 2 (P E CO 2 ) and use of the Enghoff modification of the Bohr equation.…”

Two Steps Forward in Bedside Monitoring of Lung Mechanics: Transpulmonary Pressure and Lung Volume

“…FRC measurements must be evaluated in conjunction with data regarding oxygenation as well as tidal compliance [33][34][35][36]. Although the latter r elates inversely to the stiff ness of the lung and/or chest wall, the tidal compliance traditionally used at the bedside does not necessarily track lung volume, as further increments of PEEP above a specifi c level may simply cause overdistension -indicated by accompanying increases of elastance [33].…”

“…Although the latter r elates inversely to the stiff ness of the lung and/or chest wall, the tidal compliance traditionally used at the bedside does not necessarily track lung volume, as further increments of PEEP above a specifi c level may simply cause overdistension -indicated by accompanying increases of elastance [33]. Studies conducted in lun g injury models have investigated the relationship between FRC and tidal compliance [33][34][35]. In a porcine oleic-ac id-inj ury study, Rylander et al [37] found that FRC was a more sensitive indicator of PEEP-induced aeration than was compliance.…”