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Breathing reserve at the lactate treshold to differentiate ventilatory from cardiovascular exercise limitation? FREE TO VIEW

Marc Meysman, MD*; Marc Noppen, PhD; Sonja Van Poyer, RN; Bea Van Elewijck, RN; Walter Vincken, PhD
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Vrije Universiteit Brussel, Brussels, Belgium


Chest. 2004;126(4_MeetingAbstracts):767S. doi:10.1378/chest.126.4_MeetingAbstracts.767S-a
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PURPOSE:  To investigate the utility of the breathing reserve index at the lactate treshold (BRiLT), defined as the ratio of the minute ventilation (VE) at LT/maximal voluntary ventilation (MVV= FEV1X40) to differentiate ventilatory (VL) from cardiovascular exercise limitation (CVL).

METHODS:  Prospective determination of BRiLT in 356 consecutive symptom-limited cycle-ergometer tests in 323 patients, 178 men and 145 women, performed between Januari 2000 and December 2003. Tests were considered maximal if a VL, defined as VEmax/MVV >80%, was reached or if a CVL,defined as achieving >80% of the predicted maximum heart rate, or a combination of both was reached. Breath-by-breath expired gas analysis was used and LT was determined non-invasively by the dual-methods approach (V-slope combined with ventilatory equivalents).The cut-off for BRiLT was set at >42% as proposed by Medoff et al. (1).

RESULTS:  For all patients, the BRiLT >42% predicted a VL at maximal exercise with a sensitivity of 71% and a specificity of 95%. In the 110 tests performed in 95 COPD patients the sensitivity increased to 82% and the specificity decreased to 92%. The best results were obtained in COPD patients with pure VL. 7/8 had a BRiLT of >42%. However a LT could not be determined in 43% of the COPD patients compared to 15% of the non-COPD patients.

CONCLUSION:  The BRiLT, a variable measured at submaximal exercise, accurately distinguishes COPD patients with and without a ventilatory limitation to exercise but has a poor discriminatory sensitivity in non-COPD patients especially if they attain both a CVL and VL.

CLINICAL IMPLICATIONS:  The use of the BRiLT is valuable in the interpretation of cardiopulmonary exercise tests in COPD patients who have reduced effort or perform submaximal exertion.

DISCLOSURE:  M. Meysman, None.

Tuesday, October 26, 2004

2:30 PM- 4:00 PM


Medoff et al.Chest1998;113:913–918. [CrossRef]




Medoff et al.Chest1998;113:913–918. [CrossRef]
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