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Table 1 Most common bias to consider before an ultrasound assessment of diaphragmatic function

From: Mechanical ventilation weaning issues can be counted on the fingers of just one hand: part 1

 Affected parameters
Poor echographic transthoracic window  
 Splenectomy (left hemidiaphragm)ØØ
Altered starting position of hemidiaphragm  
 Downward: COPD, asthma, PLEFFØ 
 Upward: abdominal hypertension, ascites, supine positionØ 
Iatrogenic impaired function  
 Drugs (sedative, myorelaxants, etc.)ØØ
Mechanical ventilation  
 Inspiratory positive pressureØ 
Operator-dependent factors  
 a angle other than 90°Ø 
 ZOA identificationa Ø
  1. DE diaphragmatic excursion, DTF diaphragm thickening fraction, COPD chronic obstructive pulmonary disease, PLEFF pleural effusion, PEEP positive end-expiratory pressure, a angle angle between M-Mode and hemidiaphragm examined, ZOA zone of apposition
  2. aThe further away from the ribs, the smaller the DTF will be