Changes in blood hemoglobin and blood gases PaO2 and PaCO2 in severe COPD overa three-year telemonitored program of long-term oxygen treatment

Abstract

BackgroundInformation on the effects of long-term oxygen treatment (LTOT) on blood hemoglobin (Hb) in severe COPD are limited. The aim was to assess blood Hb values in severe COPD, and investigate the time-course of both Hb and blood gas changes during a 3-year telemetric LTOT.MethodsA cohort of 132 severe COPD patients (94 males; 71.4 years ± 8.8 sd), newly admitted to the tele-LTOT program, was investigated. Subjects were divided according to their original blood Hb: group A: <13 g/dL; group B: ≥13 < 15 g/dL; group C: ≥ 5 < 16 g/dL; group D: ≥16 g/dL. Blood Hb (g/dL), PaO2 and PaCO2 (mmHg), SaO2 (%), and BMI were measured at LTOT admission (t0), and at least quarterly over three years (t1-t3). Wilcoxon test was used to compare t0 vs. t1 values; linear regression to assess a possible Hb-BMI relationship; ANOVA to compare changes in Hb time-courses over the 3 years.ResultsLTOT induced a systematic increase of PaO2, and changes were significant since the first year (from 52.1 mmHg ± 6.6sd to 65.1 mmHg ± 8.7 sd, p < 0.001). Changes in SaO2 were quite similar. Comparable and equally significant trends were seen in all subgroups (p < 0.001). PaCO2 dropped within the first year of LTOT (from 49.4 mmHg ± 9.1sd to 45.9 mmHg ±7.5 sd, p < 0.001): the t0-t1 comparison proved significant (p < 0.01) only in subgroups with the highest basal Hb, who showed a further PaCO2 decline over the remaining two years (p < 0.001). Hb tended to normalization during LTOT only in subgroups with basal Hb > 15 g/dl (ANOVA p < 0.001); anemic subjects (Hb < 13 g/dl) ameliorated not significantly in the same period (ANOVA = 0.5). Survival was independent of the original blood Hb. Anemia and polyglobulia are differently prevalent in COPD, the latter being the most represented in our cohort. LTOT affected both conditions, but to a different extent and according to different time-courses. The most striking Hb improvement was in polyglobulic patients in whom also PaO2, PaCO2 and SaO2 dramatically improved. In anemic subjects effects were smaller and slower, oxygenation being equally ameliorated by LTOT.ConclusionsLTOT effects on Hb and PaCO2 are regulated by an Hb-dependent gradient which seems independent of the original impairment of blood gases and of effects on oxygenation.

Anaemia in chronic obstructive pulmonary disease: an insight into its prevalence and pathophysiology

“…Boutou [8] [2,4,[7][8][9]14,21], several have applied the ICD 9/10 codes [13,[22][23][24] or identified COPD patients from existing databases without describing the diagnostic criteria in detail [19]. Thus, it is possible that in these studies, patients with respiratory symptoms of airflow obstruction without fulfilling spirometric criteria for COPD were misclassified, creating more variation regarding anaemia prevalence.…”

Long-Term Oxygen Therapy

“…The low levels of hemoglobin appear to be due to resistance to the effects of erythropoietin, the concentration of which is elevated in these patients [67]. In our recent study [68] Hb tended to normalize during LTOT only in subgroups with basal blood Hb > 15 g/dL (anova p < 0.001), while anemic subjects (Hb < 13 g/dL) showed progressive but not significant changes in Hb in the same period (anova = 0.5). Mean survival of patients was independent of the original Hb blood concentration.…”

“…In patients with advanced COPD and resting hypoxemia, some studies have detected no benefit from LTOT on HRQoL [57][58][59], or neuropsychiatric functioning [54,[60][61], while others suggest a positive influence on either HRQoL [54,[62][63], or neuropsychiatric functioning [12,57,[64][65][66][67]. A few investigators have looked at the effects of outpatient LTOT on these outcomes in COPD patients with isolated exertion-related hypoxemia, again with some studies showing small improvements in neuropsychiatric functioning or HRQoL [64], whereas others have not [62,[68][69].…”

“…This might have reflected the fact that lightweight portable oxygen devices were not readily available in this 1996 study. The benefits of ambulatory LTOT have been questioned by several investigators, at least in part because of observed poor adherence with this method [59,64,68,[140][141]. A Canadian study reported an average use of outpatient oxygen of only about 15 minutes/day [59], whereas a recent study in the United States observed that outpatient oxygen was used for only 2.5 hours/day, but its use to enhance ADL was not investigated [141].…”

“…The value of supplemental oxygen to treat exertion-related hypoxemia in patients who do not manifest resting daytime hypoxemia is controversial [28,[38][39]47, 71, 102, 106, 165-171], perhaps because not all patients with COPD and breathlessness manifest hypoxemia during exertion and perhaps because many patients do not seem to use this therapy very frequently [42,59,62,64,68,140,[172][173][174][175]. Nevertheless, supplemental oxygen during exertion/exercise has been shown to hasten recovery from exercise-induced dynamic hyperinflation [36,41,170], increase exercise endurance capacity [28, 38-42, 71, 107, 165, 176-178] and may improve HRQoL by promoting increased mobility and thus independence [64].…”