Table 3

Mean (SD) differences between healthy controls (HC) and patients with chronic heart failure (CHF) in inspiratory muscle strength, pulmonary mechanics, ventilatory breathing pattern, inspiratory muscle load, and endurance time during negative pressure threshold loading

HCCHFp valueHC − CHF (95 % CI)
RR = respiratory rate; Vt = tidal volume; Ve = minute ventilation; Ti = inspiratory time; Te = expiratory time; Ti/Ttot = duty cycle; Cldyn = dynamic lung compliance; Poesmax = maximum negative oesophageal pressure during an inspiratory manoeuvre; Tlim = endurance time; mean Poes per cycle = mean inspiratory oesophageal pressure per breath; PTPoes per cycle = inspiratory oesophageal pressure time product per breath; PTPoes per cycle/Poesmax = inspiratory muscle load to capacity ratio; Poespeak/TTPoespeak = inspiratory muscle contraction rate; Poesexp = peak expiratory oesophageal pressure; 95% CI = 95% confidence intervals.
*All age matched controls were instructed to stop the test at 30 minutes (1800 s).
RR (breaths/min)15.5 (6.4)20.5 (3.6)0.05−5.0 (−9.9 to −0.1)
Vt (ml)640 (287)574 (164)0.565.6 (−154 to 285)
Ve (l/min)8.8 (3.0)11.4 (2.7)0.05−2.7 (−5.4 to −0.02)
Ti (s)1.9 (0.8)1.9 (0.4)0.950.02 (−0.60 to 0.63)
Te (s)3.0 (5.8)1.1 (0.3)0.031.9 (0.3 to 3.5)
Ti/Ttot0.43 (0.14)0.62 (0.07)0.001−0.2 (−0.3 to −0.1)
Cldyn (ml/cm H2O)157 (43)98 (42)0.00659.1 (19.2 to 99.0)
Poesmax (cm H2O)−117.7 (23.6)−100.0 (18.3)0.1−17.6 (−37.5 to 2.2)
Tlim (s)1800*306 (190)<0.00011494 (1368 to 1620)
Mean Poes/breath (cm H2O)−37.8 (10.2)−32.9 (7.3)0.24−4.9 (−13.2 to 3.5)
PTPoes per cycle/Poesmax0.13 (0.05)0.21 (0.04)0.001−0.17 (−0.11 to −0.03)
Poespeak/TTPoespeak (cm H2O/s)−95.5 (35.2)−53.5 (19.9)0.004−42.0 (−69.0 to −14.9)
Poesexp (cm H2O)−1.9 (2.7)1.7 (2.1)0.004−3.6 (−5.8 to −1.3)