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Mechanisms of improvement of respiratory failure in patients with COPD treated with NIV.

Nickol AH, Hart N, Hopkinson NS, Hamnegård CH, Moxham J, Simonds A, Polkey MI - Int J Chron Obstruct Pulmon Dis (2008)

Bottom Line: We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics.Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035).Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.

View Article: PubMed Central - PubMed

Affiliation: Respiratory Muscle Laboratory, Royal Brompton Hospital, London, UK. annabel@medex.org.uk

ABSTRACT

Background: Noninvasive ventilation (NIV) improves gas-exchange and symptoms in selected chronic obstructive pulmonary disease (COPD) patients with hypercapnic respiratory failure. We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics.

Methods: Nineteen stable COPD patients (forced expiratory volume in one second 35% predicted) were studied at baseline (DO), 5-8 days (D5) and 3 months (3M) after starting NIV.

Results: Ventilator use was 6.2 (3.7) hours per night at D5 and 3.4 (1.6) at 3M (p = 0.12). Mean (SD) daytime arterial carbon-dioxide tension (PaCO2) was reduced from 7.4 (1.2) kPa to 7.0 (1.1) kPa at D5 and 6.5 (1.1) kPa at 3M (p = 0.001). Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035). At D5 there was an increase in the hypercapnic ventilatory response and some volitional measures of inspiratory and expiratory muscle strength, but not isolated diaphragmatic strength whether assessed by volitional or nonvolitional methods.

Conclusion: These findings suggest decreased gas trapping and increased ventilatory sensitivity to CO2 are the principal mechanism underlying improvements in gas-exchange in patients with COPD following NIV. Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.

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Related in: MedlinePlus

Effect of NIV on lung volumes (left panel) and gas trapping measured as TLC – alveolar volume, (right panel). Mean (SEM) values at D0, D5, and 3M are shown. The fall in TLC and gas trapping were significant (p = 0.035 and 0.04, respectively).Abbreviations: NIV, noninvasive ventilation; SEM, standard error of mean. TLC, total lung capacity.
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f4-copd-3-453: Effect of NIV on lung volumes (left panel) and gas trapping measured as TLC – alveolar volume, (right panel). Mean (SEM) values at D0, D5, and 3M are shown. The fall in TLC and gas trapping were significant (p = 0.035 and 0.04, respectively).Abbreviations: NIV, noninvasive ventilation; SEM, standard error of mean. TLC, total lung capacity.

Mentions: Thirteen patients carried out lung volume measurements on all 3 occasions, and 16 patients at baseline and D5. There was a significant fall in TLC from 6.04 (1.65) L at baseline to 5.82 (1.65) L at D5 and 5.86 (1.66) L at 3M (p = 0.035). There was a trend towards reduction of residual volume (RV) (p = 0.07) and no change in functional residual capacity (FRC) (p = 0.11), Figure 4, left panel. There was a significant decrease in gas trapping, (TLC minus alveolar volume) from baseline to three months (p = 0.04, Figure 4, right panel). There were no consistent changes in spirometry or carbon-monoxide transfer factor. There was a significant change in static chest wall compliance (p = 0.01), with an increase at D5, and fall back to below baseline at 3M, and no change in static lung compliance (p = 0.13).


Mechanisms of improvement of respiratory failure in patients with COPD treated with NIV.

Nickol AH, Hart N, Hopkinson NS, Hamnegård CH, Moxham J, Simonds A, Polkey MI - Int J Chron Obstruct Pulmon Dis (2008)

Effect of NIV on lung volumes (left panel) and gas trapping measured as TLC – alveolar volume, (right panel). Mean (SEM) values at D0, D5, and 3M are shown. The fall in TLC and gas trapping were significant (p = 0.035 and 0.04, respectively).Abbreviations: NIV, noninvasive ventilation; SEM, standard error of mean. TLC, total lung capacity.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2629992&req=5

f4-copd-3-453: Effect of NIV on lung volumes (left panel) and gas trapping measured as TLC – alveolar volume, (right panel). Mean (SEM) values at D0, D5, and 3M are shown. The fall in TLC and gas trapping were significant (p = 0.035 and 0.04, respectively).Abbreviations: NIV, noninvasive ventilation; SEM, standard error of mean. TLC, total lung capacity.
Mentions: Thirteen patients carried out lung volume measurements on all 3 occasions, and 16 patients at baseline and D5. There was a significant fall in TLC from 6.04 (1.65) L at baseline to 5.82 (1.65) L at D5 and 5.86 (1.66) L at 3M (p = 0.035). There was a trend towards reduction of residual volume (RV) (p = 0.07) and no change in functional residual capacity (FRC) (p = 0.11), Figure 4, left panel. There was a significant decrease in gas trapping, (TLC minus alveolar volume) from baseline to three months (p = 0.04, Figure 4, right panel). There were no consistent changes in spirometry or carbon-monoxide transfer factor. There was a significant change in static chest wall compliance (p = 0.01), with an increase at D5, and fall back to below baseline at 3M, and no change in static lung compliance (p = 0.13).

Bottom Line: We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics.Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035).Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.

View Article: PubMed Central - PubMed

Affiliation: Respiratory Muscle Laboratory, Royal Brompton Hospital, London, UK. annabel@medex.org.uk

ABSTRACT

Background: Noninvasive ventilation (NIV) improves gas-exchange and symptoms in selected chronic obstructive pulmonary disease (COPD) patients with hypercapnic respiratory failure. We hypothesized NIV reverses respiratory failure by one or all of increased ventilatory response to carbon-dioxide, reduced respiratory muscle fatigue, or improved pulmonary mechanics.

Methods: Nineteen stable COPD patients (forced expiratory volume in one second 35% predicted) were studied at baseline (DO), 5-8 days (D5) and 3 months (3M) after starting NIV.

Results: Ventilator use was 6.2 (3.7) hours per night at D5 and 3.4 (1.6) at 3M (p = 0.12). Mean (SD) daytime arterial carbon-dioxide tension (PaCO2) was reduced from 7.4 (1.2) kPa to 7.0 (1.1) kPa at D5 and 6.5 (1.1) kPa at 3M (p = 0.001). Total lung capacity decreased from 107 (28) % predicted to 103 (28) at D5 and 103 (27) % predicted at 3M (p = 0.035). At D5 there was an increase in the hypercapnic ventilatory response and some volitional measures of inspiratory and expiratory muscle strength, but not isolated diaphragmatic strength whether assessed by volitional or nonvolitional methods.

Conclusion: These findings suggest decreased gas trapping and increased ventilatory sensitivity to CO2 are the principal mechanism underlying improvements in gas-exchange in patients with COPD following NIV. Changes in some volitional but not nonvolitional muscle strength measures may reflect improved patient effort.

Show MeSH
Related in: MedlinePlus