title: The suitability of EIT to estimate EELV in a clinical trial compared to oxygen wash-in/wash-out technique.
abstract: BACKGROUND
  Open endotracheal suctioning procedure (OSP) and recruitment manoeuvre (RM) are known to induce severe alterations of end-expiratory lung volume (EELV). We hypothesised that EIT lung volumes lack clinical validity. We studied the suitability of EIT to estimate EELV compared to oxygen wash-in/wash-out technique.
  
  
  METHODS
  Fifty-four postoperative cardiac surgery patients were enrolled and received standardized ventilation and OSP. Patients were randomized into two groups receiving either RM after suctioning (group RM) or no RM (group NRM). Measurements were conducted at the following time points: Baseline (T1), after suctioning (T2), after RM or NRM (T3), and 15 and 30 min after T3 (T4 and T5). We measured EELV using the oxygen wash-in/wash-out technique (EELVO2) and computed EELV from EIT (EELVEIT) by the following formula: EELVEITTx,y…=EELVO2+ΔEELI×VT/ΔZ. EELVEIT values were compared with EELVO2 using Bland-Altman analysis and Pearson correlation.
  
  
  RESULTS
  Limits of agreement ranged from -0.83 to 1.31 l. Pearson correlation revealed significant results. There was no significant impact of RM or NRM on EELVO2-EELVEIT relationship (p=0.21; p=0.23).
  
  
  CONCLUSIONS
  During typical routine respiratory manoeuvres like endotracheal suctioning or alveolar recruitment, EELV cannot be estimated by EIT with reasonable accuracy.
authors.forename: Jan
authors.initials: J
authors.lastname: Karsten
authors.forename: Torsten
authors.initials: T
authors.lastname: Meier
authors.forename: Peter
authors.initials: P
authors.lastname: Iblher
authors.forename: Angela
authors.initials: A
authors.lastname: Schindler
authors.forename: Hauke
authors.initials: H
authors.lastname: Paarmann
authors.forename: Hermann
authors.initials: H
authors.lastname: Heinze
mesh_terms: D000368:Aged; D000465:Algorithms; D002986:Clinical Trials as Topic / Q000379:methods; D005260:Female; D006801:Humans; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D010992:Plethysmography, Impedance / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods*; D012123:Pulmonary Ventilation / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013990:Tidal Volume / Q000502:physiology*