Hyponatremia Clinical Update, July 22, 2011

The latest in clinical research for hyponatremia.

In young children undergoing craniofacial surgery, Ringer’s lactate (RL) may be a preferred crystalloid over normal (0.9%) saline (NS) for intravenous fluid replacement because metabolic acidosis is less frequent, with no increased incidence of hyponatremia, according to a study published in The Journal of Craniofacial Surgery.

The researchers note that pediatric craniofacial surgery requires large amounts of intravenous fluid replacement that may alter the ionic composition of body compartments. RL and NS solutions are commonly used, but they have different advantages and disadvantages.

“Our hypothesis was that there would be more acidosis with NS but with no advantage of NS over RL regarding the incidence of hyponatremia. Our objective was to determine whether acid-base and electrolyte outcomes could guide fluid management in this group of patients,” the researchers wrote.

The retrospective study focused on 122 children younger than five years who underwent craniofacial surgery: 63 received only NS (NS group) and 59 received RL (RL group). Blood gases, plasma sodium, and potassium concentrations were analyzed during two different periods: one to two hours from anesthetic induction (P-1) and two to four hours from anesthetic induction (P-2). Statistical comparisons were made with χ test and t-test, as appropriate.

The researchers found that acidosis was more frequent in NS group than in RL patients during P-1 and P-2: 66% and 80% in the NS group versus 26% and 37% in the RL group. Severe acidosis (pH ≤ 7.25) occurred more frequently in those receiving NS (39%) than RL (8%); and so was a base excess of -5 or less: NS = 53% and RL = 16%.

“The incidence of hyponatremia (Na < 135 mmol/L) was similar in both groups: 40% (NS) and 26% (RL) during P-1 and 52% (NS) and 50% (RL) during P-2,” the researchers concluded.

Appropriateness and Complications of the use of Spironolactone in Patients Treated in a Heart Failure Clinic

In patients with congestive heart failure (CHF) on optimal therapy with ACE inhibitors and β blockers, appropriate spironolactone use and close follow-up by a dedicated heart failure team can minimize the risk for adverse events and complications such as hyponatremia, according to a study published recently in the European Journal of Internal Medicine.

The researchers undertook the research project because the widespread use of spironolactone in patients with CHF has resulted in side effects and complications. They analyzed a cohort of patients treated by a dedicated CHF team in order to examine the tolerability and safety of spironolactone in clinical practice.

“We retrospectively evaluated data on 157 patients who were followed by the heart failure clinic, of whom 100 patients on maximal treatment (all on β blockers, 99% on ACE inhibitors) received spironolactone,” the researchers wrote. “The complications following spironolactone use were defined as: hyperkalemia with serum K 5.2mEq/l; creatinine 2.0mg/dl; hyponatremia with serum Na 135mEq/l, hypotension and side effects such as gynecomastia and abdominal pain.”

At one year follow-up, six patients developed hyperkalemia (range 5.3-5.9); four of them had K >5.5mEq/l. Two patients developed hyponatremia. Six patients stopped spironolactone: one for gynecomastia, two for worsening renal failure and hyperkalemia, two for hyperkalemia (5.9mEq/l), and one for bradycardia.

The researchers noted that there was an increase in mean creatinine level at one year (1.12±0.35 vs. 1.21±0.38mg/dl, p=0.02); however, no significant changes were found in GFR (99.9±33.5 vs. 65.7±27.7mlmin(-1)1.73m(-2), p=ns) and potassium (4.5±0.4 vs. 4.6±0.5mEq/l, p=ns).

“We found improvement of GFR by >10% in 19 patients and worsening by >10% in 38 patients. No patient was hospitalized or required urgent treatment for spironolactone-related side effects,” the researchers concluded.

SourcesFluid Replacement in Craniofacial Pediatric Surgery: Normal Saline or Ringer’s Lactate? [The Journal of Craniofacial Surgery]

Appropriateness and Complications of the use of Spironolactone in Patients Treated in a Heart Failure Clinic [European Journal of Internal Medicine]