Background Long term Oxygen therapy (LTOT) has been shown to have survival benefits in patients with COPD when therapeutic levels are achieved (PO2 >8.0 kPa, saturations >92%). But for some patients, loss of hypoxic ventilatory drive, can lead to development of worsening ventilatory failure and symptomatic hypercapnia during oxygen titration. Current guidelines recommend use of nocturnal NIV in conjunction with LTOT in clinically stable patients who develop a respiratory acidosis and/or a rise in PaCO2 by >1 kPa (7.5 mmHg) during an LTOT assessment on two repeated occasions, but the evidence for this approach is lacking. We present a case series of patients on LTOT who were commenced on NIV for this indication, and look at arterial blood gas outcomes, survival time and hospital admissions.
Methods Patients on both LTOT and NIV were identified using our local database and medical notes were reviewed. Results were analysed using a paired T-test and expressed as means with standard deviations.
Results A case series of 15 patients with COPD on LTOT and NIV were identified. The mean (range) age was 68 (53–83) and mean FEV1% predicted was 29%. Mean (SD) pre-treatment pH on LTOT was 7.36 (± 0.67) and post treatment with NIV pH 7.41 (±0.38), p = 0.089. Mean LTOT pCO2 was 8.09 kPa (±1.25), and post LTOT/NIV treatment levels dropped to 7.03 kPa (±0.85), p = 0.001; with a significant improvement in PO2 from 7.26 kPa (±0.64) to 8.87 kPa (±1.15) p < 0.005. PaO2 increased to therapeutic range (≥ 8.0 kPa) in 80% of patients after commencing NIV with LTOT.
Mean (SD) number of hospital admissions in the 12 months before and after the introduction of LTOT/NIV significantly reduced from 0.87 (±0.74) to 0.27 (±0.59), p = 0.023 (Figure 1). In patients with COPD, the mean survival time from starting NIV in addition to LTOT was 30 months.
Conclusion The addition of NIV to LTOT therapy can facilitate therapeutic oxygen delivery, whilst managing hypercapnia. Concurrent NIV and LTOT use can also reduce hospital admissions and increase survival times.
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