Wednesday June 11, 2008
Pulmonary hypertension and electrolytes: Does sodium tells us any story

With aging and overweight population we are seeing an increasing number of patients in our ICU with severe secondary pulmonary hypertension. As we are aware that hyponatremia is associated with decompensated cardiac failure and poor prognosis in patient with left ventricular systolic dysfunction.

A recent study by Forfia [1] also concluded that hyponatremia is strongly associated with right heart failure and poor survival in Pulmonary Arterial Hypertension (PAH), thus emphasizing the importance of associated hyponatremia further.

(Limitations: small number of subjects)

Design: Prospective study

Methods: 40 patients with PAH were followed and examined the relationship between serum sodium and right heart function as well as survival.

Measurements and Main Results: Hyponatremia (Na less than/=136 mEq/L) patients were

• more symptomatic (11/13 World Health Organization [WHO] class III/IV vs. 12/27 WHO class III/IV; P = 0.02),
• had more peripheral edema (69 vs. 26%; P = 0.009),
• had higher hospitalization rates (85 vs. 41%; P = 0.009) than normonatremic subjects
• Hyponatremic subjects had higher right atrial pressure (14 ± 6 vs. 9 ± 3 mm Hg; P less than 0.001), lower stroke volume index (21 ± 7 vs. 32 ± 10 ml/m2; P less than 0.01), larger right ventricular: left ventricular area ratio (1.8 ± 0.4 vs. 1.3 ± 0.4; P less than 0.001), and lower tricuspid annular plane systolic excursion (1.4 ± 0.3 vs. 2.0 ± 0.6 cm; P = 0.001), despite similar mean pulmonary artery pressure.
• The 1- and 2-year survival estimates were 93% and 85%, and 38% and 15% for normonatremic and hyponatremic subjects, respectively (log-rank x2 = 25.19, P less than 0.001).
• The unadjusted risk of death (hazard ratio) in hyponatremic compared with normonatremic subjects was 10.16 (95% CI, 3.42–30.10, P less than 0.001)

Hyponatremia predicted outcome after adjusting for WHO class, diuretic use, as well as right atrial pressure and cardiac index.

Reference: click to get abstract

Abstract: Forfia PR, Mathai SC, Fisher MR, Housten-Harris T, et al. Hyponatremia Predicts Right Heart Failure and Poor Survival in Pulmonary Arterial Hypertension. AJRCCM 2008: (177); 1364-1369