Background: In patients with acute left heart failure (LHF), orthopnea has also been related to the occurrence or worsening of expiratory flow limitation (EFL) in the supine position. We wished to assess whether short-term treatment with vasodilators and diuretics was able to abolish supine EFL and whether this could help to control orthopnea in patients with acute LHF.
Methods: In nine nonobese (ie, mean [± SD] body mass index, 24 ± 5 kg/m2), never-smoker patients (two men and seven women; mean age, 77 ± 7 years) with acute LHF (mean ejection fraction, 43 ± 15%), we assessed EFL by the negative expiratory pressure method and dyspnea by the Borg scale, with patients in both the seated and supine positions, before and after short-term treatment with vasodilators and diuretics until hospital discharge. Orthopnea was defined as a positive difference in the Borg score between measurements made with the patient in the supine and seated positions. Postural variations in the end-expiratory lung volume were inferred from changes in inspiratory capacity (IC) that were measured under the same circumstances.
Results: Before treatment, with the patient in the seated position the mean dyspnea score was 1.5 ± 0.5, the mean IC was 1.49 ± 0.38 L, seven patients were non-flow-limited, and two patients were flow-limited. During recumbency, the mean dyspnea score was 2.7 ± 0.5 (p < 0.01 vs seated position values), the mean IC was 1.66 ± 0.45 L, and seven patients exhibited EFL. After a mean duration of 17 ± 8 days of treatment (range, 7 to 28 days), EFL was detected in two patients only in the supine position, IC increased both in the seated position (1.65 ± 0.34 L; p < 0.01) and the supine position (1.81 ± 0.41 L; p = 0.07) position, and, although only two patients denied orthopnea, the mean dyspnea score during recumbency actually decreased to 1.9 ± 1.0 (p < 0.05).
Conclusions: Our results indicate that short-term treatment with vasodilators and diuretics is able to control orthopnea and to remove supine EFL in most patients with acute LHF, suggesting a posture-related increase in bronchial obstruction as the main mechanism of EFL, which appears to play a role in the occurrence and severity of orthopnea in these circumstances.