Am. J. Respir. Crit. Care Med., Vol 149, No. 4, Apr 1994, 925-929.
Ventilatory load characteristics during ventilatory muscle training
MJ Belman, WC Botnick, SD Nathan and KH Chon
Division of Pulmonary Disese, Cedars-Sinai Medical Center, Los Angeles, California 90025.
The response of skeletal muscle to training is influenced by both the
intensity and nature of the training stimulus. In this study we
investigated the characteristics of the ventilatory load applied to the
ventilatory muscles during several different modes of ventilatory muscle
training. Patients with chronic obstructive pulmonary disease (COPD)
performed the following breathing maneuvers: (1) Unloaded hyperpnea (UH),
(2) resistive breathing through a fixed orifice (0.5 cm diameter) at
frequencies of 15 and 30 breaths/min (RT15, RT30), (3) loaded breathing
through a threshold valve set at 30% of the PImax at frequencies of 15 and
30 breaths/min (TT15, TT30), and (4) repetitive maximal inspiratory
maneuvers against a closed shutter (PImax). During these maneuvers were
recorded airflow and pressures at the month and esophagus, and from these
measurements we derived VE and the work of breathing (WOB), tension time
index (TTI), and pressure time product (PTP). The VE during UH was
significantly higher than all other modes (p < 0.01), whereas the Pesmax
was significantly lower during UH than during the resistive and loaded
maneuvers (p < 0.01). The WOB did not differ during UH, TT30, and RT30,
but was significantly higher in all three modes than at TT15 and RT15 (p
< 0.05). During RT30 the TTI was higher than during TT30, TT15, and RT15
(p < 0.05), whereas the TTI during UH was significantly lower than
during other maneuvers (p < 0.01). As expected, the highest Pesmax and
PTP were found during the PImax maneuver. These data show that important
qualitative differences in ventilatory muscle loading can be achieved by
means of different devices and breathing strategies.(ABSTRACT TRUNCATED AT
250 WORDS)
