Chest
Volume 128, Issue 2, August 2005, Pages 657-662
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Clinical Investigations
Outcome of Patients With Stable COPD Receiving Controlled Noninvasive Positive Pressure Ventilation Aimed at a Maximal Reduction of Paco2

https://doi.org/10.1378/chest.128.2.657Get rights and content

Study objectives

The role of noninvasive positive pressure ventilation (NPPV) has been well established in the treatment of acute hypercapnic respiratory failure due to COPD. However, evidence for a sustained improvement in blood gas levels and survival in patients with stable hypercapnic COPD following NPPV is still lacking. There is concern that this might be due to low inspiratory pressures of < 18 cm H2O used in previous studies, which thereby did not achieve a reduction of Paco2. Therefore, the 2-year survival and changes in lung function and blood gas levels were analyzed in patients with stable hypercapnic COPD in whom controlled pressure-limited NPPV was titrated to achieve a maximal improvement in Paco2

Design

Retrospective study between March 1997 and September 2003

Setting

General ward of a university hospital

Patients

Thirty-four consecutive patients with stable (mean pH 7.40 ± 0.03) hypercapnic COPD (mean age, 63.4 ± 9.7 years [± SD]; mean body mass index, 28.3 ± 7.3 kg/m2)

Measurements and results

Daytime Paco2during spontaneous breathing decreased by 6.9 ± 8.0 (95% confidence interval, − 9.9 to − 3.9), from 53.3 ± 4.8 to 46.4 ± 7.0 mm Hg (p < 0.001); while daytime Pao2increased by 5.8 ± 9.4 (95% confidence interval, 2.3 to 9.3), from 51.7 ± 8.8 to 57.5 ± 9.3 mm Hg (p = 0.002); and FEV1increased by 0.14 ± 0.16 (95% confidence interval, 0.08 to 0.20), from 1.03 ± 0.54 to 1.17 ± 0.59 L (p < 0.001) after 2 months of NPPV. This was achieved with mean inspiratory pressures of 27.7 ± 5.9 cm H2O (range, 17 to 40 cm H2O) at a mean respiratory rate of 20.8 ± 2.5 breaths/min (range, 14 to 24 breaths/min). The 2-year survival rate was 86%

Conclusions

Controlled NPPV using a mean inspiratory pressure of 28 cm H2O is well tolerated over longer periods and can improve blood gas levels and lung function. Prospective, randomized controlled trials of high-intensity NPPV are required to evaluate its role in patients with stable hypercapnic COPD

Section snippets

Patients

All patients with COPD who were stable and hypercapnic, and who presented with typical symptoms of HRF such as fatigue, dyspnea, and morning headache despite supplemental oxygen and administration of bronchodilators were offered NPPV. There were no predefined criteria to decide which patients were not to receive NPPV. Patients who were established on NPPV between March 1997 and September 2003 were included in the analysis. All patients were treated on the general ward at the Department of

Results

Forty-eight patients were identified from the registry, in whom COPD was diagnosed as the leading cause of chronic HRF and who received NPPV for HMV (Fig 1). Fourteen patients did not qualify for further analysis: 5 patients were established on pressure-limited NPPV during unstable disease; 6 patients received volume-limited ventilation during unstable disease; data of 3 patients were not available: 1 patient moved to another area; 1 patient discontinued NPPV due to long-term normalization of

Discussion

In the present analysis, controlled NPPV using relatively high inspiratory pressures with a mean of 28 cm H2O has been shown to significantly improve lung function and blood gas levels during spontaneous breathing in patients with stable hypercapnic COPD. Thereby, FEV1increased by a mean of 0.14 L, Paco2could be decreased by a mean of nearly 7 mm Hg, and Pao2could be increased by nearly 6 mm Hg following 2 months of predominantly nocturnally applied NPPV. This is in contrast to a 8 of four RCTs

Conclusion

Controlled NPPV using a high mean inspiratory pressure of 28 cm H2O is well tolerated over a prolonged period by patients with stable HRF due to COPD after careful adaptation to NPPV in the hospital. This treatment can lead to a significant improvement in lung function and blood gas levels during spontaneous breathing. Further RCTs using NPPV with higher inspiratory pressures are needed to verify the benefits of NPPV on outcome in these patients.

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