Occurrence of respiratory alkalosis in continuous ambulatory peritoneal dialysis patients with pulmonary disease

Continuous ambulatory peritoneal dialysis (CAPD) patients are prone to develop respiratory alkalosis when hypoxemia occurs secondary to pulmonary problems. This is due to "fixed" bicarbonate levels that do not allow for an unlimited degree of hyperventilation. Recognition of this problem is important because treatment with oxygen or acidification with ammonium chloride is effective in avoiding severe alkalemia in these patients.

Acid-base balance in chronic peritoneal dialysis patients

Endogenous acid production has never been measured directly in dialysis patients and an empiric formula is used to estimate acid production from their protein catabolic rate. We have studied acid-base balance in 19 stable CAPD patients attending the peritoneal dialysis clinic of Mount Sinai Hospital. They obtained a 24 hour collection of peritoneal dialysis fluid and urine while consuming their usual diet and performing their usual activities. Total alkali gain was calculated from net GI alkali absorption plus urinary net acid excretion plus alkali gain from dialysate, while total acid production was measured directly from the urinary and dialysate excretions of sulfate and organic anions. Net GI alkali absorption was estimated from the difference between cations (Na + K+Ca + Mg) and anions (Cl + 1.8P) in the 24 hour dialysate and urine collections minus the daily total amount of lactate infused. All of our patients had a normal or high serum bicarbonate concentration, which was stable with time. Total alkali gain was virtually identical to total acid production (54.2 vs. 52.4 mEq/day) which suggests that these patients were in neutral acid-base balance. Net GI alkali absorption (22.7 mEq/day) was one of the same range as that of chronic renal failure patients not on dialysis and represented almost one half of the total daily alkali gain. The daily acid production of 52.4 mEq/day was numerically equal to 84% of the protein catabolic rate expressed as g/day, which is similar to the predicted value of 77% of PCR reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-base disorders in hyperglycemia of insulin-dependent diabetic patients on chronic dialysis

The authors studied hyperglycemia occurring in insulin-dependent diabetic patients on chronic dialysis to determine the types of associated acid-base disorders, their treatment, and any differences from hyperglycemia in diabetic patients with intact renal function. Eighty-eight episodes of serum glucose greater than 25 mmol/L were observed, 23 in hemodialysis patients and 65 in patients on continuous peritoneal dialysis. Treatment consisted of low-dose insulin in 77 episodes and low-dose insulin plus saline in 11; no base was administered. Seventeen episodes (19%) presented with ketoacidosis. Arterial blood gas determinations were carried out at presentation in 37 of the episodes without ketoacidosis. Of these, 12 had respiratory alkalosis, six had respiratory acidosis and severe pulmonary edema, 14 had other single or mixed acid-base disorders, and only five had normal acid-base status. Insulin corrected the ketoacidosis in all instances and both pulmonary edema and respiratory acidosis in five of six instances. In eight cases metabolic alkalosis developed during treatment, without external acid loss. At the completion of treatment respiratory alkalosis was present in half the cases. No difference was noted between patients treated with hemodialysis or peritoneal dialysis. Insulin alone is sufficient for the management of hyperglycemia in dialysis patients. Certain acid-base disorders persist, but do not need further treatment. Hyperglycemia in patients on dialysis is characterized by infrequent development of metabolic acidosis and frequent presentation with respiratory alkalosis, by respiratory acidosis that is corrected by insulin, and by metabolic alkalosis developing during treatment without external cause.