title: A randomized trial of noninvasive positive end expiratory pressure in patients with acquired immune deficiency syndrome and hypoxemic respiratory failure.
abstract: BACKGROUND
  Acquired immunodeficiency syndrome (AIDS) is a pandemic disease commonly associated with respiratory infections, hypoxemia, and death. Noninvasive PEEP has been shown to improve hypoxemia. In this study, we evaluated the physiologic effects of different levels of noninvasive  PEEP in hypoxemic AIDS patients.
  
  
  METHODS
  Thirty AIDS patients with acute hypoxemic respiratory failure received a randomized sequence of noninvasive PEEP (5, 10, or 15 cm H(2)O) for 20 min. PEEP was provided through a facial mask with pressure-support ventilation (PSV) of 5 cm H(2)O  and an F(IO(2)) of 1. Patients were allowed to breathe spontaneously for a 20-min washout period in between each PEEP trial. Arterial blood gases and clinical variables were recorded after each PEEP treatment.
  
  
  RESULTS
  The results indicate that oxygenation improves linearly  with increasing levels of PEEP. However, oxygenation levels were similar regardless of the first PEEP level administered (5, 10, or 15 cm H(2)O), and only the subgroup that received an initial treatment of the lowest level of PEEP (ie, 5 cm H(2)O) showed further improvements  in oxygenation when higher PEEP levels were subsequently applied. The P(aCO(2)) also increased in response to PEEP elevation, especially with the highest level of PEEP (ie, 15 cm H(2)O). PSV of 5 cm H(2)O use was associated with significant and consistent  improvements in the subjective sensations of dyspnea and respiratory rate reported by patients treated with any level of PEEP (from 0 to 15 cm H(2)O).
  
  
  CONCLUSIONS
  AIDS patients with hypoxemic respiratory failure improve oxygenation in response to a progressive sequential elevation  of PEEP (up to 15 cm H(2)O). However, corresponding elevations in P(aCO(2)) limit the recommended level of PEEP to 10 cm H(2)O. At a level of 5 cm H(2)O, PSV promotes an improvement in the subjective sensation of dyspnea regardless of the PEEP level  employed.
authors.affiliation: Emergency Department, Emilio Ribas Institute of Infectious Diseases, São Paulo, Brazil. cfda@uol.com.br
authors.forename: Carlos Frederico Dantas
authors.initials: CF
authors.lastname: Anjos
authors.forename: Guilherme Paula Pinto
authors.initials: GP
authors.lastname: Schettino
authors.forename: Marcelo
authors.initials: M
authors.lastname: Park
authors.forename: Vladimir Silva
authors.initials: VS
authors.lastname: Souza
authors.forename: Augusto
authors.initials: A
authors.lastname: Scalabrini Neto
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000150:complications* / Q000382:microbiology / Q000503:physiopathology; D018806:APACHE; D000163:Acquired Immunodeficiency Syndrome / Q000150:complications* / Q000503:physiopathology; D000328:Adult; D000368:Aged; D004417:Dyspnea / Q000503:physiopathology; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D010043:Outcome and Process Assessment, Health Care; D011020:Pneumonia, Pneumocystis / Q000150:complications* / Q000382:microbiology / Q000503:physiopathology; D011175:Positive-Pressure Respiration / Q000379:methods*; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D056152:Respiratory Rate; D016896:Treatment Outcome