Esophageal and transpulmonary pressures in acute respiratory failure.

Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA, USA.
Critical Care Medicine (Impact Factor: 6.15). 05/2006; 34(5):1389-94. DOI: 10.1097/01.CCM.0000215515.49001.A2
Source: PubMed

ABSTRACT Pressure inflating the lung during mechanical ventilation is the difference between pressure applied at the airway opening (Pao) and pleural pressure (Ppl). Depending on the chest wall's contribution to respiratory mechanics, a given positive end-expiratory and/or end-inspiratory plateau pressure may be appropriate for one patient but inadequate or potentially injurious for another. Thus, failure to account for chest wall mechanics may affect results in clinical trials of mechanical ventilation strategies in acute respiratory distress syndrome. By measuring esophageal pressure (Pes), we sought to characterize influence of the chest wall on Ppl and transpulmonary pressure (PL) in patients with acute respiratory failure.
Prospective observational study.
Medical and surgical intensive care units at Beth Israel Deaconess Medical Center.
Seventy patients with acute respiratory failure.
Placement of esophageal balloon-catheters.
Airway, esophageal, and gastric pressures recorded at end-exhalation and end-inflation Pes averaged 17.5 +/- 5.7 cm H2O at end-expiration and 21.2 +/- 7.7 cm H2O at end-inflation and were not significantly correlated with body mass index or chest wall elastance. Estimated PL was 1.5 +/- 6.3 cm H2O at end-expiration, 21.4 +/- 9.3 cm H2O at end-inflation, and 18.4 +/- 10.2 cm H2O (n = 40) during an end-inspiratory hold (plateau). Although PL at end-expiration was significantly correlated with positive end-expiratory pressure (p < .0001), only 24% of the variance in PL was explained by Pao (R = .243), and 52% was due to variation in Pes.
In patients in acute respiratory failure, elevated esophageal pressures suggest that chest wall mechanical properties often contribute substantially and unpredictably to total respiratory impedance, and therefore Pao may not adequately predict PL or lung distention. Systematic use of esophageal manometry has the potential to improve ventilator management in acute respiratory failure by providing more direct assessment of lung distending pressure.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Respiratory mechanics refers to the expression of lung function through measures of pressure and flow. From these measurements, a variety of derived indices can be determined, such as volume, compliance, resistance, and work of breathing. Plateau pressure is a measure of end-inspiratory distending pressure. It has become increasingly appreciated that end-inspiratory transpulmonary pressure (stress) might be a better indicator of the potential for lung injury than plateau pressure alone. This has resulted in a resurgence of interest in the use of esophageal manometry in mechanically ventilated patients. End-expiratory transpulmonary pressure might also be useful to guide the setting of PEEP to counterbalance the collapsing effects of the chest wall. The shape of the pressure-time curve might also be useful to guide the setting of PEEP (stress index). This has focused interest in the roles of stress and strain to assess the potential for lung injury during mechanical ventilation. This paper covers both basic and advanced respiratory mechanics during mechanical ventilation.
    Respiratory care 11/2014; 59(11):1773-94. · 1.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The optimal method for estimating transpulmonary pressure (i.e. the fraction of the airway pressure transmitted to the lung) has not yet been established.
    Intensive Care Medicine 08/2014; · 5.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lung-protective ventilator strategies are considered standard practice in the care of patients with the acute respiratory distress syndrome (ARDS). To minimize ventilator-induced lung injury, attention is directed at avoidance of alveolar overdistention and cyclical opening and closing. The lowest possible plateau pressure and tidal volume (VT) should be selected. A reasonable target VT in all mechanically ventilated patients is 6 mL/kg. A topic of much controversy is the optimal setting of positive end-expiratory pressure (PEEP). Results of a meta-analysis using individual patient data from three randomized controlled trials suggest that higher PEEP should be used for moderate and severe ARDS, whereas lower PEEP may be more appropriate in patients with mild ARDS. PEEP should be set to maximize alveolar recruitment while avoiding overdistention. Volume and pressure limitation during mechanical ventilation can be described in terms of stress and strain. Fraction of inspired oxygen (Fio 2) and PEEP are typically titrated to maintain arterial oxygen saturation (Spo 2) of 88 to 95% (Pao 2 55-80 mm Hg). There is currently no clear proven benefit for advanced modes.
    Seminars in Respiratory and Critical Care Medicine 08/2014; 35(4):418-430. · 2.75 Impact Factor

Full-text (2 Sources)

Available from
Nov 21, 2014