Table 2 Electromyography (EMG) and respiratory variables during resting breathing with mouthpiece when seated and supine
Obese group, seatedNon-obese group, seatedp ValueObese group, supineNon-obese group, supinep Value
EMGdi (%max)21.9 (9.0)8.4 (4.0)<0.00124.7 (8.2)**7.0 (3.4)<0.001
EMGneck (%max)5.6 (6.3)2.0 (1.7)0.0046.8 (10.7)2.6 (1.6)0.036
EMGpara (%max)7.7 (4.3)4.4 (3.0)0.0019.7 (9.2)5.0 (2.9)0.010
EMGabdominal (%max)3.3 (3.1)1.6 (1.2)0.0054.0 (2.8)1.5 (1.4)<0.001
Pressure swing, Poes (cm H2O)9.6 (2.9)5.3 (2.2)<0.00116.0 (5.0)***6.9 (2.0)***<0.001
Pressure swing, Pgas (cm H2O)5.0 (2.3)4.9 (1.7)0.9323.2 (1.4)***3.5 (1.3)***0.371
Pressure swing, Pdi (cm H2O)12.9 (3.8)8.9 (2.3)<0.00118.2 (4.5)***9.7 (2.3)*<0.001
End-expiratory baseline pressure, Poes (cm H2O)4.0 (4.2)−2.0 (2.7)<0.00112.8 (4.8)***5.1 (3.5)***<0.001
End-expiratory baseline pressure, Pgas (cm H2O)15.8 (5.5)10.9 (5.7)0.00113.0 (7.8)*7.8 (3.5)**<0.001
Respiratory rate (breaths/min)16.4 (3.1)16.0 (4.5)0.69316.9 (4.2)15.7 (4.5)0.293
Minute ventilation (l/min)10.1 (3.0)8.9 (1.7)0.06010.0 (2.5)8.9 (2.7)0.099
VT (l)0.64 (0.26)0.61 (0.20)0.5800.62 (0.22)0.61 (0.24)0.797
PEEPi (cm H2O)1.4 (1.5)0.5 (0.3)0.0015.3 (3.6)***0.7 (0.5)<0.001

  • EMGdi, EMG of the diaphragm; EMGneck, EMG of the neck muscles (sternocleidomastoid), EMGpara, EMG of the parasternal intercostals muscles; EMGabdominal, EMG of the abdominal (external oblique) muscles; PEEPi, intrinsic positive end-expiratory pressure; Pdi, transdiaphragmatic pressure; Pgas, gastric pressure; Poes, oesophageal pressure; VT, tidal volume.

  • Baseline pressures were measured at end-expiration.

  • PEEPi was small but slightly higher in the obese group when seated.

  • Reported p values refer to comparison of obese vs non-obese group, seated and supine, respectively.

  • *p<0.05, **p<0.01, ***p<0.001 refer to comparisons of parameters seated vs supine.