Efficacy of conivaptan and hypertonic (3%) saline in treating hyponatremia due to syndrome of inappropriate antidiuretic hormone in a tertiary Intensive Care Unit

Safety of Rapid Intermittent Bolus versus Slow Continuous Infusion of Hypertonic Saline for Managing Symptomatic Severe Hyponatremia: A Systematic Review and Meta-analysis

AIMS

Three percent hypertonic saline (3NS) is an established treatment for severe hyponatremia. The optimal regimen for administering 3NS for severe hyponatremia, with the aim to minimize side effects is not known. This systematic review and meta-analysis aimed to evaluate the safety profile of rapid intermittent bolus (RIB) versus slow continuous infusion (SCI) of 3NS for managing symptomatic severe hyponatremia.

METHODS

Databases were searched for studies evaluating the use of RIB versus SCI/conventional therapy of 3NS for managing symptomatic severe hyponatremia. The primary outcome was to evaluate the occurrence of overcorrection of hyponatremia. Secondary outcomes were to evaluate the need for relowering therapy, duration of hospital stay, changes in sodium levels, osmotic demyelination syndrome (ODS), and mortality.

RESULTS

Data from three studies (290 patients) with severe hyponatremia was analyzed. Patients receiving RIB had a similar occurrence of overcorrection (relative risk [RR]: 1.59 [0.40, 6.35]; I2 = 61%; P = 0.51), need for relowering treatment to bring down serum sodium back to the normal range (RR: 2.53 [0.32, 20.20]; I2 = 81%; P = 0.38), ODS (RR: 2.24 [0.09, 57.18]; P = 0.63) and mortality (RR: 0.51 [0.08, 3.30]; I2 = 31%; P = 0.48), as compared to those receiving SCI. Patients receiving RIB had a marginally higher duration of hospital stay, which approached statistical significance (mean difference: 3.71 days [-0.18, 7.59]; I2 = 0%; P = 0.06).

CONCLUSION

Both RIB and SCI of hypertonic saline were safe and effective for managing severe symptomatic hyponatremia. The reduced duration of hospital stay with SCI of hypertonic saline may suggest this may be the optimal way of administering hypertonic saline.

Acute Severe Hypovolemic Hyponatremia in a Patient on Intravenous Dexamethasone

Hyponatremia is a commonly encountered electrolyte imbalance with varied etiology. Hyponatremia can be broadly classified as hypotonic, isotonic, and hypertonic hyponatremia based on the tonicity of plasma. Hypotonic hypovolemia is further classified as hypovolemic, euvolemic, and hypervolemic hyponatremia based on the volume status. Gastrointestinal fluid and electrolyte losses, secondary to vomiting and diarrhea, is an important predisposition to hypotonic hypovolemic hyponatremia. The renin-angiotensin-aldosterone system (RAAS) and antidiuretic hormone (ADH) play a pivotal role in maintaining intravascular volume and serum sodium concentration. Dexamethasone is a potent glucocorticoid with minimal mineralocorticoid activity. It negatively affects the hypothalamic-pituitary-adrenal axis and the renin-angiotensin-aldosterone system, particularly with prolonged administration. In the index case, acute severe hypovolemic hyponatremia ensued on the third post-procedure (endovascular embolization of traumatic carotico-cavernous fistula (CCF)) day while the patient was on intravenous dexamethasone. This case underscores that even small fluid and electrolyte imbalance in the setting of dexamethasone therapy may lead to severe hypovolemic hyponatremia, which requires specific therapy.

Efficacy of oral tolvaptan versus 3% hypertonic saline for correction of hyponatraemia in post-operative patients

Background and Aims:

Hyponatraemia is frequent in post-operative patients and may be corrected with hypertonic saline (HTS). Oral tolvaptan is used to treat hypervolaemic or euvolaemic hyponatraemia. This study was performed to assess the efficacy of oral tolvaptan in correcting postoperative hyponatraemia compared to HTS.

Methods:

This prospective, randomised study was conducted in 40 symptomatic patients with serum sodium level ≤130 mEq/L. In Group H (n = 20), 3% HTS was infused at 20–30 mL/h aiming for correction of 6 mEq/L/day. Group T received oral tolvaptan 15 mg on the 1^st day. If daily correction was <4 mEq/L, the dose was increased by 15 mg/day to a maximum of 45 mg. The primary outcome was serum sodium concentration 48 hours after starting treatment. Paired t-test was used to compare changes in sodium levels.

Results:

Baseline sodium and values at 12, 24 and 48 h were comparable in both groups. At 72 h, Group T had significantly higher sodium levels as compared to Group H (133.4 ± 1.9 vs. 131.3 ± 2.4 mEq/L). Intragroup analysis had shown a significant increase in sodium levels from baseline values in both groups at 12, 24, 48 and 72 h. Group H had a significantly lower potassium level and lower negative fluid balance on day 3.

Conclusion:

Oral tolvaptan and 3% HTS were equally effective in correcting hyponatraemia at 48 hours, but serum sodium levels were higher at 72 hours after oral tolvaptan.