Elsevier

Respiratory Medicine

Volume 103, Issue 10, October 2009, Pages 1477-1483
Respiratory Medicine

Clinical impact of leak compensation during non-invasive ventilation

https://doi.org/10.1016/j.rmed.2009.04.020Get rights and content
Under an Elsevier user license
open archive

Summary

Background

This study aimed to assess the impact of leak compensation capabilities during pressure- and volume-limited non-invasive positive-pressure ventilation (NPPV) in COPD patients.

Methods

Fourteen patients with stable hypercapnic COPD who were receiving long-term NPPV were included in the study. For both modes of NPPV, a full face mask and an artificial leak in the ventilatory circuit were used at three different settings, and applied during daytime NPPV, either without leakage (setting I), with leakage during inspiration only (setting II), and with leakage during inspiration and expiration (setting III). Ventilation pattern was pneumotachygraphically recorded.

Results

NPPV was feasible with negligible leak volumes, indicating optimal mask fitting during the daytime (setting I). In the presence of leakage (settings II and III), the attempt to compensate for leak was only evident during pressure-limited NPPV, since inspiratory volumes delivered by the ventilator increased from 726 ± 129 (setting I) to 1104 ± 164 (setting II), and to 1257 ± 166 (setting III) ml during pressure-limited NPPV, respectively (all p < 0.001); however, they remained stable during volume-limited NPPV. Leak compensation resulted in a decrease in leakage-induced dyspnea. However, 83%/87% (setting II/III) of the additionally-delivered inspiratory volume during pressure-limited NPPV was also lost via leakage. Expiratory volume was higher in setting II compared to setting III (both p < 0.001), indicating the presence of significant expiratory leakage.

Conclusions

The attempt at leak compensation largely feeds the leakage itself and only results in a marginal increase of tidal volume. However, pressure-limited – but not volume-limited – NPPV results in a clinically-important leak compensation in vivo. Trial registration: www.uniklinik-freiburg.de/zks/live/uklregister/Oeffentlich.html Identifier: UKF001272.

Keywords

Chronic obstructive pulmonary disease
Leakage
Mask
Non-invasive positive-pressure ventilation
Respiratory insufficiency

Abbreviations

ANOVA
analysis of Variance
BMI
body mass index
COPD
chronic obstructive pulmonary disease
CO2
carbon dioxide
FEV1
forced expiratory volume in 1 s
FVC
forced vital capacity
fb
breathing frequency
HCO3
standard bicarbonate
HRF
hypercapnic respiratory failure
ID
inner diameter
IPAP
inspiratory positive airway pressure
LTOT
long-term oxygen therapy
ml
milliliter
mm
millimeter
min
minute(s)
NPPV
non-invasive positive-pressure ventilation
PEEP
positive end expiratory pressure
PCV
pressure controlled ventilation
PaCO2
arterial partial pressure of carbon dioxide
PaO2
arterial partial pressure of oxygen
PIP
peak inspiratory pressures
Pmean
mean inspiratory pressures
ref
reference
RV
residual volume
SaO2
oxygen saturation
SD
standard deviation
TLC
total lung capacity
V-exp
expiratory volumes
V-insp
inspiratory volumes
V-leak
leakage volumes
VCV
volume controlled ventilation

Cited by (0)