Hyponatremia as a complication of cardiac catheterization: a prospective study

Acute Symptomatic Hyponatremia After Computed Tomography Renal Protocol

Computed tomography (CT) is a widely used imaging modality. Although hyponatremia after CT imaging is rare, its effects can be devastating. Hyperosmolar radiocontrast acts as effective osmoles and causes fluid migration from intracellular into extracellular compartment. Dilutional hyponatremia will ensue if translocation of fluid is in excess of diuresis. This case report detailed an unusual case of acute symptomatic hyponatremia after CT renal protocol and the treatments given after its recognition.

The use of iodinated contrast media in patients with end-stage renal disease

Iodinated contrast agents are well tolerated in ESRD patients. Certain types of ICM, i.e., LOCM and the nonionic agents are associated with better safety profiles. Current available evidence, although not optimal, does not support the need for additional hemodialysis for ICM removal to preserve residual renal function or to treat other potential toxicities of ICM. However, limiting exposure to ICM is a prudent measure in ESRD patients given ICM’s potential toxicity; close monitoring of patients with poor cardiac function is also recommended in subjects receiving higher doses of ICM, especially those receiving HOCM.

Increased plasma osmolar gap is predictive of contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CIAKI) is a common complication after percutaneous coronary artery intervention (PCI). It is urgent to find a novel, easily measurable and accurate predictor for the early detection of CIAKI. Hyperosmolarity and large amounts of contrast media are risk factors for CIAKI. However, there is no study on plasma osmolar gap as a predictor of CIAKI. We enrolled 89 patients undergoing elective PCI and tested changes of serum sodium, osmolar gap, and renal function at 0, 6, 12 and 24 hours. Plasma osmolar gap was calculated using the following formula: measured plasma osmolarity - [2(Na) + serum urea nitrogen/2.8 + glucose/18]. CIAKI was defined as follows: increase in serum creatinine of ≥ 50%, increase in serum creatinine of ≥ 0.3 mg/dL, or decrease in estimated glomerular filtration rate of ≥ 25% within 24 hours after PCI. The incidence of CIAKI was 13.5% (12/89 patients). The CIAKI group had higher plasma osmolar gaps 6 hours after PCI. The adjusted hazard ratio of the plasma osmolar gap from hour 6 (1-mOsm/L increments) to the development of CIAKI was 1.12 (95% confidence interval [CI], 1.01-1.26; P = 0.041). Sensitivity and specificity of 7 mOsm/L or higher plasma osmolar gap at hour 6 were 70.0% and 76.6%, respectively (area under the ROC curve = 0.77 [95% CI, 0.65-0.89]). Increased plasma osmolar gap may precede the development of CIAKI in patients undergoing PCI. In conclusion, plasma osmolar gap may be a useful predictor for the development of CIAKI.

Economic impact of hyponatremia in hospitalized patients: a retrospective cohort study

BACKGROUND

Hyponatremia is the most common electrolyte abnormality seen in general hospital patients, with an incidence of 1% to 6% in the United States.

OBJECTIVE

We aimed to evaluate the impact of varying levels of hyponatremia at admission on length of stay (LOS) and cost of care in adult hospitalized patients.

METHODS

A retrospective cohort study was conducted using an existing clinical database from a large academic-setting hospital. All adult admissions from January 2004 through May 2005 with serum sodium level at admission of < or = 134 mEq/L were separated into 2 cohorts: patients with moderate-to-severe hyponatremia (serum sodium level at admission of < or = 129 mEq/L, n = 547) and patients with mild-to-moderate hyponatremia (serum sodium level of 130-134 mEq/L, n = 1500). ICD-9 diagnosis codes for these 2047 admissions with hyponatremia were used to identify a cohort of 7573 admissions with the same principal admitting diagnoses and a serum sodium level of 135 to 145 mEq/L. Differences in hospital LOS, intensive care unit (ICU) admission rate, and median total costs per admission between cohorts were examined using multiple linear regression, logistic, and quantile regression models.

RESULTS

Admissions with hyponatremia had significantly longer hospital LOS than those admitted without hyponatremia (median LOS: moderate-to-severe hyponatremia, 8 days; mild-to-moderate hyponatremia, 8 days; normal, 6 days; P < 0.001). Patients with more severe hyponatremia were also more likely to be admitted to the ICU during the hospital stay (moderate-to-severe hyponatremia, 32%; mild-to-moderate hyponatremia, 26%; normal, 22%; P < 0.001). These trends were also reflected in the total costs per admission, with median costs of $16,606 for moderate-to-severe hyponatremia cases, $14,266 for mild-to-moderate hyponatremia cases, and $13,066 for normal admissions (P < 0.001).

CONCLUSIONS

Hyponatremia at admission was associated with increased LOS and cost of care for hospitalized patients. Interventions or pharmacotherapies for the prompt treatment of hyponatremia could potentially reduce morbidity and LOS, thereby reducing the utilization of health care resources.

Hyponatraemia in patients with normal pressure hydrocephalus

BACKGROUND

In clinical practice, hyponatraemia was frequently found in patients with hydrocephalus. We conducted this study to determine the prevalence and risk factors for hyponatraemia in patients with normal pressure hydrocephalus (NPH).

METHODS

We retrospectively reviewed all patients with NPH who were admitted to China Medical University Hospital between 1998 and 2006. Hyponatraemia was defined as a plasma sodium concentration < 135 mEq/l on admission. Possible risk factors between patients with and without hyponatraemia were analysed using Student's t-test or chi2 test. The association between hyponatraemia and possible factors was analysed using multivariate logistic regression. The odds ratio was calculated to determine the effect of possible risk factors.

RESULTS

A total of 146 patients (84 men and 62 women) who had NPH with a mean age of 66.1 +/- 15.9 years old were reviewed and 33 (22.6%) patients were found having hyponatraemia. Patients who developed hyponatraemia had a significantly higher prevalence of hypertension, use of nasogastric tube (NG), bed-ridden status and fever. In multivariate logistic regression, the presence of hypertension and the use of NG were two important risk factors for hyponatraemia. The odds ratio (95% CI) for hypertension and NG were 2.604 (95% CI: 1.136-5.967, p = 0.024) and 7.179 (95% CI: 2.3-22.409, p = 0.001) respectively.

CONCLUSION

Hyponatraemia is not uncommon in patients with NPH. Physicians should be aware of this complication and obtain necessary laboratory examination for early detection of hyponatraemia.

Hospital-acquired hyponatremia—why are hypotonic parenteral fluids still being used?

Hospital-acquired hyponatremia can be lethal. There have been multiple reports of death or permanent neurological impairment in both children and adults. The main factor contributing to the development of hospital-acquired hyponatremia is routine use of hypotonic fluids in patients in whom the excretion of free water, which is retained in response to excess arginine vasopressin (AVP), might be impaired. The practice of administering hypotonic parental fluids was established over 50 years ago, before recognition of the fact that there are numerous potential stimuli for AVP production in most hospitalized patients. Virtually all neurological morbidity resulting from hospital-acquired hyponatremia has been associated with administration of hypotonic fluids. Multiple prospective studies have shown that 0.9% NaCl is effective prophylaxis against hyponatremia. There is not a single report in the literature of neurological complications resulting from the use of 0.9% NaCl in non-neurosurgical patients. Patients at greatest risk of developing hyponatremic encephalopathy following hypotonic fluid administration are children, premenopausal females, postoperative patients, and those with brain injury or infection, pulmonary disease or hypoxemia. When hyponatremic encephalopathy develops, immediate administration of 3% NaCl is essential. In this Review, we discuss the question of why administering hypotonic fluids is unphysiologic and potentially dangerous, the settings in which isotonic fluids should be administered to prevent hyponatremia, and the appropriate treatment of hyponatremic encephalopathy.

Novel risk factors for hospital-acquired hyponatraemia: a matched case-control study

BACKGROUND

Hospital-acquired hyponatraemia is a common and potentially serious condition. Risk factors for hospital-acquired hyponatraemia have not been studied in a controlled fashion. Methods From 1501 patients in whom serum sodium (S(Na)) was determined, 50 cases with hospital-acquired hyponatraemia (in-hospital decrease in S(Na)>or= 7 mmol/l to < 136 mmol/l) were identified. They were matched by age, gender and department to 69 normonatraemic controls.

RESULTS

In the 50 cases, S(Na) fell from 141 +/- 2 to 130 +/- 4 mmol/l, while controls remained normonatraemic. During the development of hyponatraemia, C-reactive protein (CRP) increased in cases (median from 23 to 146 mg/l), whereas it decreased in controls (median from 31 to 24 mg/l, P = 0.008). Additional factors associated with hospital-acquired hyponatraemia included diabetes mellitus (16/50 vs. 10/69, P = 0.009) and the use of insulin (12/50 vs. 4/69, P = 0.007), antibiotics (41/50 vs. 38/69, P = 0.006) and opioids (32/50 vs. 27/69, P = 0.005). Multivariate conditional logistic regression showed that the use of insulin [odds ratio (OR) 10.5, 95% confidence interval (CI) 1.5-72.4], antibiotics (OR 4.5, 95% CI 1.4-14.6) and opioids (OR 2.9, 95% CI 1.1-7.8) was also independently associated with hospital-acquired hyponatraemia. Mortality (6/50 vs. 1/69, P = 0.04) and intensive care admission (15/50 vs. 7/69, P = 0.008) were higher in cases.

CONCLUSIONS

An increase in CRP and the use of insulin, antibiotics and opioids are novel risk factors for hospital-acquired hyponatraemia. These factors represent interesting new clues regarding the pathophysiology of hospital-acquired hyponatraemia, suggesting that the acute-phase response, pain and/or direct drug effects could be involved in the release of antidiuretic hormone.

Contrast-induced translocational hyponatremia and hyperkalemia in advanced kidney disease

BACKGROUND

In patients with advanced kidney disease, administration of effective osmolar agents may lead to hyponatremia, hyperkalemia, metabolic acidosis, and intravascular expansion. To our knowledge, osmolar effects of contrast agents in patients with advanced kidney disease have not been previously elucidated.

METHODS

This retrospective case series includes 5 patients with advanced kidney disease who underwent diagnostic and/or therapeutic cardiac catheterization and developed hyponatremia. Blood chemistry tests were performed before and after the procedure. Hyponatremia is defined as a plasma sodium concentration less than 135 mEq/L (mmol/L).

RESULTS

Mean precontrast and postcontrast sodium levels were 138.6 mEq/L (mmol/L) and 122.6 mEq/L (mmol/L), respectively. Plasma potassium levels increased after contrast exposure. There was no difference in degree of hyperkalemia between patients with and without diabetes. Plasma bicarbonate levels were noted to decrease after contrast exposure in 4 of 5 patients, with the exception of a patient undergoing continuous ambulatory peritoneal dialysis. There was a strong correlation between dose of contrast administered and change in sodium level, with a correlation coefficient of 0.91.

CONCLUSION

These data suggest that large volumes of contrast may result in hypertonic hyponatremia through a dual effect of exogenous fluid dilution and translocation. The fluid translocated from intracellular to extracellular spaces may lead to a decrease in sodium, chloride, and bicarbonate levels. All patients developed hyperkalemia, which may be caused by solvent drag and/or passive diffusion, in addition to impaired excretory capacity. Patients with advanced kidney disease exposed to large volumes of contrast should be monitored for osmolar-induced chemical changes so that timely postcontrast dialytic therapy can be instituted.