Expiratory flow limitation is associated with orthopnea and reversed by vasodilators and diuretics in left heart failure.

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.