Physiopathology, clinical diagnosis, and treatment of hyponatremia

Sonographic Optic Nerve Sheath Diameter as a Guide for Correction of Hyponatremia in the Emergency Department: A Cross-sectional Study

BACKGROUND

Monitoring sodium levels during the correction of hyponatremia is essential. There is cell swelling due to the movement of water from extracellular to intracellular by osmotic effect in hyponatremia. The cellular swelling in a closed space causes increased intracranial pressure (ICP). The raised ICP correlates with the optic nerve sheath diameter (ONSD). So, the research question was whether the ONSD can be used as a guide for the correction of hyponatremia.

METHODS

It was a prospective observational study conducted on patients with serum sodium below 135 mEq/L presented to the emergency department (ED). The ONSD was measured at the time of presentation and discharge of the patient. The receiver operating characteristic curve (ROC) and area under the curve (AUC) were used to test the predictive ability of the ONSD to diagnose hyponatremia.

RESULTS

A total of 54 subjects were included in the study. The mean sodium level was 109.3 mEq/L at presentation. The mean ONSD on the right side was 6.24 ± 0.71 mm and on the left side was 6.26 ± 0.64 mm at presentation to ED. The mean ONSD on the right side was 5.81 ± 0.58 mm and on the left side was 5.79 ± 0.56 mm at discharge. The ONSD was not able to predict the sodium level measured both by laboratory and POC methods.

CONCLUSION

The ONSD failed to predict the sodium level in patients with hyponatremia during the correction. The change in ONSD did not correlate with the change in sodium level.

HOW TO CITE THIS ARTICLE

Uttanganakam S, Hansda U, Sahoo S, Shaji IM, Guru S, Topno N, et al. Sonographic Optic Nerve Sheath Diameter as a Guide for Correction of Hyponatremia in the Emergency Department: A Cross-sectional Study. Indian J Crit Care Med 2023;27(4):265-269.

Hyponatremia in Infectious Diseases-A Literature Review

Hyponatremia is one of the most common water-electrolyte imbalances in the human organism. A serum sodium concentration threshold of less than 135 mmol/L is diagnostic for hyponatremia. The disorder is usually secondary to various diseases, including infections. Our review aims to summarize the diagnostic value and impact of hyponatremia on the prognosis, length of the hospitalization, and mortality among patients with active infection. The scientific literature regarding hyponatremia was reviewed using PubMed, ClinicalKey, and Web of Science databases. Studies published between 2011 and 2020 were screened and eligible studies were selected according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and specific inclusion criteria. The most common infections that were associated with hyponatremia were viral and bacterial infections, including COVID-19 (coronavirus disease 2019). The etiology varied according to the infection site, setting and patient cohort it concerned. In several studies, hyponatremia was associated with prolonged hospitalization, worse outcomes, and higher mortality rates. Hyponatremia can also play a diagnostic role in differentiating pathogens that cause a certain infection type, as it was observed in community-acquired pneumonia. Although many mechanisms leading to hyponatremia have already been described, it is impossible with any certainty to ascribe the etiology of hyponatremia to any of them.

Hypertonic saline, isotonic saline, water restriction, long loops diuretics, urea or vaptans to treat hyponatremia

Introduction: Hyponatremia is the most common fluid and electrolyte abnormality. It is associated with much higher morbidity and mortality rates than found in non hyponatremic patients.Areas covered: When the physician is faced to a hyponatremic patient he first has to confirm that hyponatremia is associated with hypoosmolality. Then he must answer to a series of questions: What is its origin? Is it acute or chronic? Which treatment is the most appropriate? We will discuss the various options for the treatment of hypotonic hyponatremia. For a better comprehensive approach of the treatment we will also discuss some pathophysiological data. The use of urea in euvolemic and hypervolemic hyponatremia will be particularly discussed. Literature was reviewed from Jan 1970 to Dec 2019.Expert opinion: Prospective studies showing the benefit in decreasing morbidity by increasing SNa in patients with chronic hyponatremia should be done. These studies should also compare the efficacy and side effects of urea therapy compare to vaptans.

Approach to and management of abnormalities in plasma sodium

The differential diagnosis between hypertonic, isotonic and hypotonic hyponatremia are presented. The help of some usual serum (urea, uric acid and TCO₂) and urine parameters (mainly osmolality and sodium concentration) are discussed and help to determine the best treatment. Morbidity associated with untreated hyponatremia and with the different treatment available is also discussed. Who to prevent and treat ODS (osmotic demyelating syndrome) is recalled. The pathophysiology and treatment of hypernatremia are also discussed.

Mild water restriction with or without urea for the longterm treatment of syndrome of inappropriate antidiuretic hormone secretion (SIADH): Can urine osmolality help the choice?

BACKGROUND

Treatment options for chronic SIADH include water restriction (WR) and urea. The usefulness of urine osmolality to guide the choice of the treatment option is not clearly defined. We hypothesized that urine osmolality can indicate whether treatment with mild water restriction alone could be successful.

METHODS

Retrospective Review of clinical and biochemical (blood and urine) data of patients with chronic SIADH treated for at least one year with mild WR (1.5-2l/day) either with or without urea.

RESULTS

Twenty nine patients were included. Nine patients were treated by mild WR. Mean serum sodium (SNa) and mean Uosm were 129±2mEq/l and 274±78mOsm/kgH2O respectively before WR, and increased to 138.5±3mEq/l and 505±87mOsm/kgH₂O (P<0.001). Eight patients were treated with mild WR and 15g urea daily, the SNa and Uosm before treatment were 127.5±3mEq/l and 340±100mOsm/kgH₂O respectively and increased to 136.5±1mEq/l and 490±151mOsm/kgH₂O (P<0.001). Four of the eight patients had a permanent low solute intake which contributed to hyponatremia. Twelve patients needed 30g urea daily combined with mild WR. The SNa and Uosm were respectively 126±2mEq/l and 595±176mOsm/kgH₂O and increased to 136.5±2mEq/l and 698±157mOsm/kgH₂O (P<0.05). Uosm increased in most of the treated patients.

CONCLUSIONS

About 30% of patients could be treated by moderate WR alone. All these patients presented an initial urine osmolality lower than 400mOsm/kgH₂O.