title: Comparing the Effects of Two Different Levels of Hyperoxygenation on Gas Exchange During Open Endotracheal Suctioning: A Randomized Crossover Study.
abstract: BACKGROUND
  Endotracheal suctioning is required for mechanically ventilated patients to maintain a patent airway. Studies show that open endotracheal suctioning affects respiratory mechanics and gas exchange. The aim of this study was to compare the effectiveness of hyperoxygenation with FIO2+ 0.20 above baseline and hyperoxygenation with FIO21.0 in preventing hypoxemia, and to determine the impact of open endotracheal suctioning on the pulmonary ventilation of critical subjects receiving mechanical ventilatory support.
  
  
  METHODS
  This prospective randomized crossover study was conducted in the ICU. Sixty-eight mechanically ventilated subjects with FIO2≤ 0.6 and requiring endotracheal suctioning were included in this study. Open endotracheal suctioning was performed using 2 different intervention sequences: hyperoxygenation of 0.20 above baseline FIO2(FIO2+ 0.20) and 1.0 hyperoxygenation (FIO21.0). Oxygenation was assessed via oxygen saturation as measured by pulse oximetry (SpO2), and changes in lung ventilation were measured via alveolar gas volume (V̇A), alveolar minute volume (V̇A min), carbon dioxide (CO2) production (V̇CO2), mixed exhaled partial pressure of CO2(P̄ECO2), exhaled tidal CO2volume (VTCO2), end-tidal CO2(PETCO2), anatomical dead space to tidal volume ratio (VD/VT), and anatomical dead space volume of each breath (VD) using volumetric capnography, and breathing frequency (f), heart rate, and mean arterial pressure using a multiparameter monitor.
  
  
  RESULTS
  SpO2levels were significantly higher within interventions (FIO2+ 0.20 and 1.0) 1 min before and after suction. Also, there was a significant increase in PETCO2, P̄ECO2, heart rate, and mean arterial pressure immediately after the procedure compared with baseline, and in VTCO2, only for FIO2+ 0.20. Baseline values were not found to be significantly different between the groups in case of any dependent variable.
  
  
  CONCLUSIONS
  In mechanically ventilated adult subjects, hyperoxygenation with FIO2+ 0.20 above baseline prevents hypoxemia. Also, transient changes in pulmonary ventilation with open circuit suctioning were confirmed by volumetric capnography analysis. (Trial registration: ClinicalTrials.gov NCT02440919).
authors.affiliation: Claretiano Centro Universitário, Santa Casa of Misericórdia Hospital, Batatais, São Paulo, Brazil. jacrfvianna@uol.com.br.
authors.forename: Jacqueline Rodrigues de Freitas
authors.initials: JR
authors.lastname: Vianna
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Paulo, Brazil.
authors.forename: Valéria Amorim
authors.initials: VA
authors.lastname: Pires Di Lorenzo
authors.affiliation: Santa Casa of Misericórdia Hospital, Batatais, São Paulo, Brazil.
authors.forename: Miléa Mara Lourenço da Silva
authors.initials: MM
authors.lastname: Simões
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Paulo, Brazil.
authors.forename: Maurício
authors.initials: M
authors.lastname: Jamami
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D062186:Arterial Pressure; D019296:Capnography; D002245:Carbon Dioxide / Q000032:analysis / Q000378:metabolism*; D018592:Cross-Over Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000517:prevention & control*; D007442:Intubation, Intratracheal; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D012121:Respiration, Artificial; D012126:Respiratory Dead Space / Q000502:physiology; D056152:Respiratory Rate; D016037:Single-Blind Method; D013396:Suction; D013990:Tidal Volume; D014132:Trachea
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: capnography; mechanical ventilation; pulmonary ventilation; respiratory mechanics; suctioning