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Table 2 Variables associated with an increase in diaphragm function* and a decrease or no change in diaphragm function between the two measurements

From: Severe but reversible impaired diaphragm function in septic mechanically ventilated patients

  Increase in diaphragm function
n = 40
Decrease or no change in diaphragm function
n = 52
p
Time between intubation and second measure, days 5 (3–6) 4 (2–6) 0.163
Time between 2 measures, days 4 (3–5) 3 (1–5) 0.134
Sepsis at inclusion, n (%) 29 (73) 22 (42) 0.004
Age, years 61 (49–72) 63 (54–71) 0.425
Male sex, n (%) 22 (55) 34 (65) 0.312
Body mass index, kg m−2 24 (21–25) 25 (23–28) 0.036
SAPS2 at inclusion 58 (35–66) 54 (45–64) 0.831
SOFA at inclusion 9 (5–11) 10 (7–12) 0.301
Comorbidities, n (%)
 Active smoking 20 (50) 25 (48) 0.855
 COPD 9 (23) 12 (23) 0.948
 Diabetes 11 (28) 14 (27) 0.951
 Cirrhosis 7 (18) 10 (19) 0.832
Primary reason for ventilation, n (%)
 Acute respiratory failure 28 (70) 27 (52) 0.080
 Shock 5 (13) 7 (13) 0.892
 Cardiac arrest 1 (3) 6 (12) 0.105
 Coma 6 (15) 12 (23) 0.333
Biological variables    
 PCT at inclusion, ng/ml 3 (0.3–20) 1.7 (0.9–7.3) 0.909
 Blood lactate at inclusion, mmol.l−1 1.8 (1.2–3.2) 2.1 (1.4–2.9) 0.838
 PaO2/FiO2 at inclusion 230 (160–305) 226 (162–306) 0.940
 PaO2/FiO2 at second measure 280 (202–327) 260 (220–333) 0.990
Sedation    
 Hypnotics at inclusion (propofol or midazolam), n (%) 33 (100) a 44 (100) c 1.000
 Sufentanyl at inclusion, n (%) 29 (88) a 38 (86) c 1.000
 Hypnotics at second measure (propofol or midazolam), n (%) 19 (56) b 16 (40) d 0.130
 Sufentanyl at second measure, n (%) 9 (26) b 14 (35) d 0.808
Organ support    
 Vasopressors, n (%) 28 (70) 38 (73) 0.745
Diaphragm function    
 Ptr,stim at inclusion, cmH2O 5.8 (4.0–8.0) 10.2 (7.0–14.3)  < 0.001
 Ptr,stim at second measure, cmH2O 10.5 (7.0–12.5) 6.9 (4.5–9.4) 0.002
 Absolute change in Ptr,stim, cmH2O 3.4 (1.8–4.8) – 1.5 (– 4.9 to – 0.6)  < 0.001
 Relative change in Ptr,stim, % 59 (32–78) – 19 (– 43 to – 7)  < 0.001
 End-expiratory diaphragm thickness at inclusion, mm 2.3 (1.9–2.9) e 2.1 (1.7–2.5) f 0.484
 End-expiratory diaphragm thickness at second measure, mm 1.9 (1.5–2.3) e 2.0 (1.7–2.2) f 0.565
  1. Categorical variables are expressed as absolute value (%) and continuous variables as median (interquartile range)
  2. * Increase in diaphragm function is defined as an increase > 10% of the change of endotracheal tube pressure induced by bilateral phrenic nerve stimulation during airway occlusion (Ptr,stim) between first measure at inclusion and second measure after switch to pressure support mode
  3. SOFA: Sepsis-related Organ Failure Assessment; SAPS 2: New Simplified Acute Physiology Score; COPD: chronic obstructive pulmonary disease; PCT: procalcitonin; PaO2/FiO2: partial arterial oxygen tension on inspired oxygen fraction ratio; Ptr,stim: endotracheal tube pressure induced by bilateral phrenic nerve stimulation during airway occlusion
  4. a Data available for 33/40 patients, b data available for 34/40 patients
  5. c Data available for 44/52 patients, d data available for 40/52 patients
  6. e Data available for 28/40 patients
  7. f Data available for 30/52 patients