title: Beyond bicarbonate: complete acid-base assessment in patients receiving intermittent hemodialysis.
abstract: Acid-base assessments in hemodialysis patients have been limited almost entirely to measurements of total CO 2 concentration, and assumptions have been made about the presence of acid-base disorders. To gain a fuller understanding of the acid-base status of stable hemodialysis patients, we analyzed measurements of pCO 2 , pH and HCO 3 - obtained in a cohort of chronic stable hemodialysis patients over a 5-year period.
  
  
  
  We reviewed acid-base measurements taken pre-dialysis from fistula blood in 53 outpatients receiving hemodialysis thrice weekly between 2008 and 2012. In these patients, pH and pCO 2 were measured using an onsite blood gas analyzer, and HCO 3 - was computed. Relevant clinical and laboratory data were obtained from medical records. Factors affecting serum HCO 3 - were identified. Simple and mixed acid-base disorders were diagnosed using accepted rules.
  
  
  
  Serum HCO 3 - was affected by age, normalized protein catabolic rate, interdialytic weight gain and length of interval between treatments. As expected, metabolic acidosis was the most common acid-base disorder, but respiratory acid-base disturbances, as simple or complex disorders, were found in 41% of the measurements. Respiratory alkalosis was seen more frequently than respiratory acidosis, but the latter disorder was more commonly associated with serious comorbidities.
  
  
  
  Respiratory acid-base disorders are an important component of the acid-base abnormalities seen in hemodialysis patients and are not identified by measuring total CO 2 concentration; hence, complete acid-base measurements are needed to determine the components of hemodialysis patients' acid-base status that are contributing to mortality risk.
authors.affiliation: Hemodialysis Unit, Maria Rosaria Clinic, Pompeii, Naples, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Marano
authors.affiliation: Department of Information and Electrical Engineering and Applied Mathematics, University of Salerno, Fisciano, Salerno, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Marano
authors.affiliation: University of Vermont, UVM Medical Center, 1 South Prospect St., Burlington, VT, USA.
authors.forename: F John
authors.initials: FJ
authors.lastname: Gennari
mesh_terms: D000136:Acid-Base Equilibrium; D000137:Acid-Base Imbalance / Q000097:blood / Q000150:complications; D000138:Acidosis / Q000097:blood*; D000368:Aged; D001639:Bicarbonates / Q000097:blood*; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D015430:Weight Gain
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide
keywords: acid-base disorders; blood gas analysis; chronic hemodialysis; chronic renal failure; hemodialysis