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

Nickol AH, Hart N, Hopkinson NS, HamnegÄrd 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

Changes in the hypercapnic ventilatory response (left panels) and TLC (right panels) versus mean hours of NIV use per night (top panels) and change in PaCO2 (bottom panels). Closed circles denote data at D5 and open circles at 3M. Dotted lines in the top panels indicate 4 hours of use per night.Abbreviations: HCVR, hypercapnic ventilatory response; NIV, noninvasive ventilation; PaCO2, arterial carbon-dioxide tension; TLC, total lung capacity.
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f5-copd-3-453: Changes in the hypercapnic ventilatory response (left panels) and TLC (right panels) versus mean hours of NIV use per night (top panels) and change in PaCO2 (bottom panels). Closed circles denote data at D5 and open circles at 3M. Dotted lines in the top panels indicate 4 hours of use per night.Abbreviations: HCVR, hypercapnic ventilatory response; NIV, noninvasive ventilation; PaCO2, arterial carbon-dioxide tension; TLC, total lung capacity.

Mentions: In contrast to patients with restrictive disease, there was no linear regression between changes in PaCO2 or ESS and hours of use, however patients using NIV for more than 4 hours per night tended to have no change or an increase in HCVR and decrease in TLC, whilst those using it for less than 4 hours had no consistent changes (Figure 5, top panels). There was also a tendency for a fall in PaCO2 to be associated with an increase in HCVR and decrease in TLC (Figure 5, bottom panels). This was significant only at 3M for HCVR (r2 = 0.35; p = 0.02).


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

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

Changes in the hypercapnic ventilatory response (left panels) and TLC (right panels) versus mean hours of NIV use per night (top panels) and change in PaCO2 (bottom panels). Closed circles denote data at D5 and open circles at 3M. Dotted lines in the top panels indicate 4 hours of use per night.Abbreviations: HCVR, hypercapnic ventilatory response; NIV, noninvasive ventilation; PaCO2, arterial carbon-dioxide tension; TLC, total lung capacity.
© Copyright Policy
Related In: Results  -  Collection

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

f5-copd-3-453: Changes in the hypercapnic ventilatory response (left panels) and TLC (right panels) versus mean hours of NIV use per night (top panels) and change in PaCO2 (bottom panels). Closed circles denote data at D5 and open circles at 3M. Dotted lines in the top panels indicate 4 hours of use per night.Abbreviations: HCVR, hypercapnic ventilatory response; NIV, noninvasive ventilation; PaCO2, arterial carbon-dioxide tension; TLC, total lung capacity.
Mentions: In contrast to patients with restrictive disease, there was no linear regression between changes in PaCO2 or ESS and hours of use, however patients using NIV for more than 4 hours per night tended to have no change or an increase in HCVR and decrease in TLC, whilst those using it for less than 4 hours had no consistent changes (Figure 5, top panels). There was also a tendency for a fall in PaCO2 to be associated with an increase in HCVR and decrease in TLC (Figure 5, bottom panels). This was significant only at 3M for HCVR (r2 = 0.35; p = 0.02).

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