Metabolic balance studies have helped to delineate changes in fluid and electrolyte metabolism consequent to various forms of bodily stress.1 These methods recently have been applied to patients with intracranial lesions.2,3 We thought that a similar study of patients undergoing pneumoencephalography might produce information regarding cerebral control of fluid and electrolyte metabolism.
Intake was limited to oral fluids, feeding formula, and intravenous fluids. The formulas were analyzed for sodium, potassium, chloride, and nitrogen. The bottles used for collecting urine were kept on ice. Stools were not collected.Twenty-four-hour urine specimens were analyzed for sodium and potassium by flame photometry, employing the Beckman Model DU spectrophotometer with Beckman Flame photometer attachment.4 Chlorides were determined by a modification of the Sendroy iodometric procedure.5 Nitrogen determinations were performed by the Pregl micro-Kjeldahl procedure, using selenium oxychloride as a catalyst. Aliquot samples from the 24-hour urine specimens were measured