HFpEF: Higher Work of Breathing During Exercise

The following is a summary of “Higher Work of Breathing During Exercise in Heart Failure With Preserved Ejection Fraction,” published in the June 2023 issue of the Chest by Villarraga et al.

It is unknown whether pulmonary changes in heart failure with preserved ejection fraction (HFpEF) affect respiratory mechanics during exercise. During exercise, are the operating lung volumes, labor of breathing, and power of breathing abnormal in patients with HFpEF? Patients with HFpEF (n = 8; median age, 71 years [IQR, 66-80 years]) and controls (n = 9; median age, 68 years [IQR, 64-74 years]) performed incremental cycling to voluntary exhaustion. During exercise, esophageal pressure, end-expiratory lung volume, and inspiratory lung volume were compared at similar absolute (30 and 50 L/min) and relative (45% of peak, 70% of height, and 100% of size) minute ventilation (VE_E). 

EELVs did not differ between patients with HFpEF and controls during exercise (P >.13 for all comparisons). EILVs were lower in patients with HFpEF compared to controls at 45% and 70% V_E peak (P .03 for all comparisons). Patients with HFpEF had lower dynamic lung compliance at 30 L/min, 50 L/min, 45% E peak, and 100% V_E peak (P<.04 for all comparisons). Compared with control participants, patients with HFpEF showed higher total Wb and Pb at 30 L/min (Wb: median, 1.08 J/L [IQR, 0.93-1.82 J/L] vs. 0.52 J/L [IQR, 0.43-0.71 J/L]; Pb: median, 36 J/min [IQR, 30-59 J/min] vs. 17 J/min [IQR, 11-23 J/min] and 50 L/min; Web: median, 1.40 J/L [IQR, 1.27-1.68 J/L] vs. 0.90 J/L [IQR, 0.74-1.05 J/L]; Pb: median, 73 J/min [IQR, 60-83 J/min] vs. 45 J/min [IQR, 33-63 J/min]; P < .01 for all). 

At 30 and 50 L/min, patients with HFpEF had higher inspiratory and expiratory resistive Wb and Pb than healthy controls (P<.04 for all). At 45% of V_E peak, total Wb was greater in patients with HFpEF than in healthy controls (P =.02). At 100% E peak, total Pb was more significant in controls than in patients with HFpEF due to higher inspiratory resistive Pb (P <.04 for both). These findings indicate that HFpEF syndrome is associated with pulmonary alterations that result in a higher Pb during exercise due to increased inspiratory and expiratory resistive Pb.

Source: sciencedirect.com/science/article/abs/pii/S001236922204209X