Shlomi D; Tel-Aviv University, Tel Aviv, Israel.
Beck T; Reuveny R; Segel MJ

Pulmonology. 30(5):452-458, 2024 Sep-Oct.

BACKGROUND: Evaluation of unexplained exercise intolerance is best
resolved by cardiopulmonary exercise testing (CPET) which enables the
determination of the exercise limiting system in most cases.
Traditionally, pulmonary function tests (PFTs) at rest are not used for
the prediction of a respiratory limitation on CPET.
OBJECTIVE: We sought cut-off values on PFTs that might, a priori, rule-in
or rule-out a respiratory limitation in CPET.
METHODS: Patients who underwent CPET in our institute were divided into
two groups according to spirometry: obstructive and non-obstructive. Each
group was randomly divided 2:1 into derivation and validation cohorts
respectively. We analyzed selected PFTs parameters in the derivation
groups in order to establish maximal and minimal cut-off values for which
a respiratory limitation could be ruled-in or ruled-out. We then validated
these values in the validation cohorts.
RESULTS: Of 593 patients who underwent a CPET, 126 were in the
obstructive and 467 in the non-obstructive group. In patients with
obstructive lung disease, forced expiratory volume in 1 second (FEV1) >=
61% predicted could rule out a respiratory limitation, while FEV1 <= 33%
predicted was always associated with a respiratory limitation. For
patients with non-obstructive spirometry, FEV1 of >= 73% predicted could
rule-out a respiratory limitation. Application of this algorithm might
have saved up to 47% and 71% of CPETs in our obstructive and
non-obstructive groups, respectively.
CONCLUSION: Presence or absence of a respiratory limitation on CPET can
be predicted in some cases based on a PFTs performed at rest.