Acid‐Base Balance and Oxygen Tension During Dialysis in Uremic Patients With Chronic Obstructive Pulmonary Disease

Abstract

Recent reports on the effects of dialysis on acid-base balance and metabolic acidosis correction in end-stage renal disease (ESRD) patients with chronic obstructive pulmonary disease (COPD) are lacking. Here, we compared acid-base balance and blood gasses among 14 patients with established COPD (group A) and eight patients with normal respiratory function (group B). The two groups were homogeneous for age, time on dialysis, and male/female ratio. At the beginning of dialysis, acid-base balance and blood gasses were comparable between patients of groups A and B. A significant difference between groups was observed only in pCO(2) at 20 min, together with a delay in pH increase. Effective correction of acidosis was reported at the end of dialysis and is not significantly affected by COPD. Nevertheless, weight loss must be carefully monitored in these patients in order to prevent hyperhydration and worsening of respiratory function.

Acid‐base homeostasis during hemodialysis: New insights into the mystery of bicarbonate disappearance during treatment

“…Our acid‐base measurements are consistent with previous studies, demonstrating little further change in blood [HCO 3 − ] after 2 hours of treatment . Blood pH rises gradually throughout the treatment, from a predialysis value of 7.38 to an end treatment value of 7.50.…”

“…Blood PCO 2 increases from 36 to 38 mm Hg within the first 15 minutes, and then does not change further until the end of dialysis when it returns to 36 mm Hg. These changes were not statistically significant, but the pattern of change is consistent with previous observations …”

“…Only a few studies have reported the pattern of rise in blood [HCO 3 − ] during a single hemodialysis treatment . These studies have uniformly shown that almost all the increase occurs during the first two hours, with little change thereafter despite a continued gradient for HCO 3 − entry from the bath solution.…”

pCO₂ Reveals Arteriovenous Fistula Recirculation in Bicarbonate Hemodialysis (RecirCO₂lation Test)

“…1 a). Therefore, as previously reported [31,36,[38][39][40] , in wellfunctioning AVF, the levels of pCO 2 are generally unmodified during whole duration of bicarbonate HD. However, in case of VAR, CO 2 comes back in arterial-line ( fig.…”

“…Apparently this is the main drawback of the analysis; however, in our experimental model, the absence of VAR is assessed by ultrasound duplex, demonstrating the absence of stenosis and adequate flow, in addition to KtV >1.2 and GIT <0.3%; moreover, the reversion of needles causes high percentages of VAR, reducing the possibility of false negative. Second, our results cannot be applied to patients affected by respiratory disease, because they were excluded from the study; however, although baseline pCO 2 in subjects with COPD is higher than in non-COPD, the trend of pCO 2 during dialysis session is comparable in both groups of patients [38][39][40] , suggesting the possible use of the 2 samples technique also in these patients. Third, due to characteristics of pCO 2 production in the dialysate, our method may be used only in case of bicarbonate HD.…”