PURPOSE: Severe hypoxemia in COPD patients in Bogotá leads to severe exercise limitation and the FIO2 needed for an adequate correction is unknown. A high FIO2, as used in some rehabilitation programs is expensive and cumbersome and incomplete correction could be inadequate. The purpose of the study was to find an adequate FIO2.
METHODS: The endurance time in a treadmill exercise was determined breathing air and oxygen (28% and 35%) administered in a randomized, controlled, single blind study in 29 patients with severe COPD (FEV1 42.9±11.9 %).
RESULTS: Breathing air: PaO2 46.5±8.2 mmHg, SpO2 72.6±6.8 %, endurance time 9.7±4.2 min, increase in lactate 2.39±1.71 mmol/L. Breathing 28% O2: PaO2 71.1±12.9 mmHg (p<0.01), SpO2 86.3±6.5 % (p<.05), endurance time 16.4±6.8 min (p>0.001), increase in lactate 1.14±1.79 mmol/L (p<0.001). Breathing 35% O2: PaO2 94.5±17 mmHg(p<0.01), SpO2 92.6±4.7 % (p<0.05) endurance time 17.6±7.0 min (p>0.001), increase in lactate 0.77±1.62 mmol/L p<0.001). The only difference between 28% and 35% was de SpO2 (p<0.05). At isotime breathing 28% O2, SpO2 increased to 87.2±61 % (p<0.01) and breathing 35% O2 increased to 93.0±3.7 % (p<0.01). The inspiratory capacity that breathing air decreased 0.544±0.257 L, breathing 28% O2 decreased 0.399±0.201 L (p<0.01) and 0.362±0.201 (p<0.03) breathing 35%. The only difference, at isotime, between 28% and 35% was de SpO2 (p<0.05). Respiratory rate decreased significantly when compared with room air and was not different breathing 28 and 35%.
CONCLUSION: The administration of oxygen at 28 and 35% significantly increased SpO2 and endurance time. The increase in endurance time was associated with a significant decrease in lactate production, respiratory rate and dynamic hyperinflation. Although the increase in SpO2 obtained with 35% was significantly higher than with 28% O2, the increase in endurance time was not significantly different.
CLINICAL IMPLICATIONS: The fact that the higher SpO2 obtained with 35% O2 did not conferred a significant advantage over 28% O2 has important clinical, logistic and economic implications, particularly for long-term oxygen therapy and rehabilitation programs.
DISCLOSURE: Dario Maldonado, No Financial Disclosure Information; No Product/Research Disclosure Information