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Ventilator beyond ventilation: impact of the increase of elastic recoil pressure of a respiratory system through positive end expiratory pressure–zero positive end expiratory pressure vs manually assisted cough vs manually assisted cough adding positive end expiratory pressure 12 cmH2O on the peak expiratory flow in mechanically ventilated patients

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Critical Care20037 (Suppl 3) :P46

  • Published:


  • Pneumothorax
  • Peak Expiratory Flow
  • Institutional Aspect
  • Secretion Clearance
  • Elastic Recoil Pressure


Physiotherapy has many techniques that are able to promote secretion clearance, decreasing airway obstruction in the attempt to improve ventilation homogeneity and exchanged blood gases [13]. These techniques aim to promote the increase of peak expiratory flow (PEF) and expiratory volume, probably through augmentation of the elastic recoil pressure produced by exsufflation forces. Our purpose was to assess the impact of the three usual modalities of bronchial hygiene on peak expiratory flow.


A prospective, experimental and blinded study.


Twenty-six patients (mean age, 60 ± 13.5 years) admitted to the Hospital Português Clinical–Surgery Intensive Care Unit, requiring total support ventilation and with positive end expiratory pressure (PEEP) of 5.5 ± 1.44 cmH2O, were assessed. Patients with a history of pulmonary disease, hemodynamic instability, rib cage and/or abdominal abnormalities, scoliosis, pregnancy, obesity, cardiac pacemaker, pneumothorax, unstable thorax and PEEP higher than 10 cmH2O were excluded. PEF was measured by Navigator Graphics Monitor (Newport Medical Instruments Inc., Newport Beach, CA, USA) during PEEP–zero positive end expiratory pressure (ZEEP), manually assisted cough with baseline PEEP (MAC), mean PEEP of 5.5 ± 1.44 cmH2O, and MAC with adding PEEP of 12 cmH2O. Techniques were performed five times for each patient, with intervals of 5 min between each technique application. The Kruskal–Wallis test was used to compare the groups. The Mann–Whitney rank-sum test was used to compare the techniques two by two. Differences with P < 0.05 were considered significant.


Means of the PEF variations are presented in Table 1. The comparison of MAC vs PEEP–ZEEP and MAC vs MAC with PEEP of 12 cmH2O showed statistical significance (P < 0.0002 and P < 0.01, respectively). When PEEP–ZEEP and MAC with PEEP of 12 cmH2O were compared, no statistical significant differences were noted.


Peak expiratory flow



0.750 ± 0.262

< 0.00001


1.070 ± 0.282

< 0.0001


1.088 ± 0.286

< 0.00001

MAC, manually assisted cough; PEEP, positive end expiratory pressure; ZEEP, zero positive end expiratory pressure.


PEEP–ZEEP and MAC with PEEP of 12 cmH2O were more efficient on the increase of peak expiratory flow than MAC with baseline PEEP. Considering that there were no statistical differences between the more efficient techniques, the relationship of risk/benefit and the institutional aspects, the choice of the technique should be powerful to consider.

Authors’ Affiliations

Department of Physiotherapy, Hospital Português, Av Princesa Isabel 02, Salvador, Bahia, Brazil
Intensive Care Unit, Hospital Português, Av Princesa Isabel 02, Salvador, Bahia, Brazil
Department of Physiotherapy, University Hospital, UNB, Brasília, DF, Brazil
University Hospital, Intensive Care Unit, UFRJ, Rio de Janeiro, RJ, Brazil


  1. Hardy KA: A review of airway clearance. New techniques, indications and recommendations. Respir Care 1994., 39:Google Scholar
  2. Van Der Schans CP, Postma DS, Koeter GH, Rubin BK: Physiotherapy and bronquial mucus transport. Eur Respir J 1999, 13: 1477-1486.View ArticlePubMedGoogle Scholar
  3. Hess DR: The evidence for secretion clearance techniques. Respir Care 2001, 46: 1276-1292.PubMedGoogle Scholar


© BioMed Central Ltd 2003