Article

Tidal hyperinflation during low tidal volume ventilation in acute respiratory distress syndrome.

Università di Torino, Dipartimento di Anestesiologia e Rianimazione, Ospedale S. Giovanni Battista-Molinette, Corso Dogliotti 14, 10126 Turin, Italy.
American Journal of Respiratory and Critical Care Medicine (Impact Factor: 11.99). 02/2007; 175(2):160-6. DOI: 10.1164/rccm.200607-915OC
Source: PubMed

ABSTRACT Tidal volume and plateau pressure limitation decreases mortality in acute respiratory distress syndrome. Computed tomography demonstrated a small, normally aerated compartment on the top of poorly aerated and nonaerated compartments that may be hyperinflated by tidal inflation.
We hypothesized that despite tidal volume and plateau pressure limitation, patients with a larger nonaerated compartment are exposed to tidal hyperinflation of the normally aerated compartment.
Pulmonary computed tomography at end-expiration and end-inspiration was obtained in 30 patients ventilated with a low tidal volume (6 ml/kg predicted body weight). Cluster analysis identified 20 patients in whom tidal inflation occurred largely in the normally aerated compartment (69.9 +/- 6.9%; "more protected"), and 10 patients in whom tidal inflation occurred largely within the hyperinflated compartments (63.0 +/- 12.7%; "less protected"). The nonaerated compartment was smaller and the normally aerated compartment was larger in the more protected patients than in the less protected patients (p = 0.01). Pulmonary cytokines were lower in the more protected patients than in the less protected patients (p < 0.05). Ventilator-free days were 7 +/- 8 and 1 +/- 2 d in the more protected and less protected patients, respectively (p = 0.01). Plateau pressure ranged between 25 and 26 cm H(2)O in the more protected patients and between 28 and 30 cm H(2)O in the less protected patients (p = 0.006).
Limiting tidal volume to 6 ml/kg predicted body weight and plateau pressure to 30 cm H(2)O may not be sufficient in patients characterized by a larger nonaerated compartment.

1 Bookmark
 · 
211 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Perspectives on invasive and noninvasive ventilatory support for critically ill patients are evolving, as much evidence indicates that ventilation may have positive effects on patient survival and the quality of the care provided in intensive care units in Brazil. For those reasons, the Brazilian Association of Intensive Care Medicine (Associação de Medicina Intensiva Brasileira - AMIB) and the Brazilian Thoracic Society (Sociedade Brasileira de Pneumonia e Tisiologia - SBPT), represented by the Mechanical Ventilation Committee and the Commission of Intensive Therapy, respectively, decided to review the literature and draft recommendations for mechanical ventilation with the goal of creating a document for bedside guidance as to the best practices on mechanical ventilation available to their members. The document was based on the available evidence regarding 29 subtopics selected as the most relevant for the subject of interest. The project was developed in several stages, during which the selected topics were distributed among experts recommended by both societies with recent publications on the subject of interest and/or significant teaching and research activity in the field of mechanical ventilation in Brazil. The experts were divided into pairs that were charged with performing a thorough review of the international literature on each topic. All the experts met at the Forum on Mechanical Ventilation, which was held at the headquarters of AMIB in São Paulo on August 3 and 4, 2013, to collaboratively draft the final text corresponding to each sub-topic, which was presented to, appraised, discussed and approved in a plenary session that included all 58 participants and aimed to create the final document.
    Revista Brasileira de Terapia Intensiva 04/2014; 26(2):89-121.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pulmonary stretch reflex plays an important role in regulation of respiratory movement. This study aimed to evaluate the effect of pulmonary stretch reflex on lung injury in rabbits with acute respiratory distress syndrome (ARDS).
    World journal of emergency medicine. 01/2011; 2(4):296-301.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionWhen alveoli collapse the traction forces exerted on their walls by adjacent expanded units may increase and concentrate. These forces may promote its re-expansion at the expense of potentially injurious stresses at the interface between the collapsed and the expanded units. We developed an experimental model to test the hypothesis that a local non-lobar atelectasis can act as a stress concentrator, contributing to inflammation and structural alveolar injury in the surrounding healthy lung tissue during mechanical ventilation.MethodsA total of 35 rats were anesthetized, paralyzed and mechanically ventilated. Atelectasis was induced by bronchial blocking: after five minutes of stabilization and pre-oxygenation with 100& oxygen, a silicon cylinder blocker was wedged in the terminal bronchial tree. Afterwards, the animals were randomized between two groups: 1) Tidal volume (VT)¿=¿10 ml/kg and positive end-expiratory pressure (PEEP)¿=¿3 cmH2O (VT10/PEEP3); and 2) VT¿=¿20 ml/kg and PEEP¿=¿0 cmH2O (VT20/zero end-expiratory pressure (ZEEP)). The animals were then ventilated during 180 minutes. Three series of experiments were performed: histological (n¿=¿12); tissue cytokines (n¿=¿12); and micro-computed tomography (microCT; n¿=¿2). An additional six, non-ventilated, healthy animals were used as controls.ResultsAtelectasis was successfully induced in the basal region of the lung of 26 out of 29 animals. The microCT of two animals revealed that the volume of the atelectasis was 0.12 and 0.21 cm3. There were more alveolar disruption and neutrophilic infiltration in the peri-atelectasis region than the corresponding contralateral lung (control) in both groups. Edema was higher in the peri-atelectasis region than the corresponding contralateral lung (control) in the VT20/ZEEP than VT10/PEEP3 group. The volume-to-surface ratio was higher in the peri-atelectasis region than the corresponding contralateral lung (control) in both groups. We did not find statistical difference in tissue interleukin-1ß and cytokine-induced neutrophil chemoattractant-1 between regions.Conclusions The present findings suggest that a local non-lobar atelectasis acts as a stress concentrator, generating structural alveolar injury and inflammation in the surrounding lung tissue.
    Critical care (London, England) 09/2014; 18(5):505. · 5.04 Impact Factor

Full-text (2 Sources)

Download
169 Downloads
Available from
Jun 10, 2014