The dialytic management of acute renal failure in the elderly

Acute kidney injury, sodium disorders, and hypercalcemia in the aging kidney: diagnostic and therapeutic management strategies in emergency medicine

This article summarizes the current literature regarding the structural and functional changes of the aging kidney and describes how these changes make the older patient more susceptible to acute kidney injury and fluid and electrolyte disorders. It discusses the clinical manifestations, evaluation, and management of hyponatremia and shows how the management of hypernatremia in geriatric patients involves addressing the underlying cause and safely correcting the hypernatremia. The current literature regarding evaluation and management of hypercalcemia in older patients is summarized. The management of severe hypercalcemia is discussed in detail. The evaluation and management of acute kidney injury is described.

Risk factors for mortality in patients with acute kidney injury and hypotension treated with continuous veno-venous hemodiafiltration

Background

Continuous veno-venous hemodiafiltration (CVVHDF) is a preferred treatment modality in hemodynamically unstable acute kidney injury (AKI) patients, because it has advantages over intermittent dialysis in terms of hemodynamic stability. However, this patient group still shows a significantly high mortality rate. To aid in the management of these high-risk patients, we evaluated the risk factors for mortality in CVVHDF-treated hypotensive AKI patients.

Methods

We studied 67 patients with AKI and hypotension who were treated with CVVHDF from February 2008 to August 2010. We reviewed patient characteristics and laboratory parameters to evaluate the risk factors for 90-day mortality.

Results

Of the 67 enrolled patients (male:female=42:25; mean age=69±14 years), 18 (27%) survived until 90 days after the initiation of CVVHDF. There was no significant difference in survival rates according to the etiology of AKI [hypovolemic shock 2/10 (20%), cardiogenic shock 4/20 (20%), septic shock 12/37 (32%)]. Univariate analysis did show significant differences between survivors and non-survivors in the frequency of ventilator use (44% vs. 76%, respectively; P=0.02), APACHE II score (29±7 vs. 34±7, respectively; P=0.01), SOFA score (11±4 vs. 13±4, respectively; P=0.03), blood pH (7.3±0.1 vs. 7.2±0.1, respectively; P=0.03), and rate of urine output <500 mL for 12 hours (50% vs. 80%, respectively; P=0.03). A multivariate Cox proportional hazards model showed that a urine output<500 mL for 12 hours was the only significant risk factor for 90-day mortality following CVVHDF treatment (odds ratio=2.1, confidence interval=1.01–4.4, P=0.048).

Conclusion

A urine output<500 mL for 12 hours before the initiation of CVVHDF is an independent risk factor for 90-day mortality in hypotensive AKI patients treated with CVVHDF.

A population-based study on the association between acute renal failure (ARF) and the duration of polypharmacy

BACKGROUND

Because of the rapid growth in elderly population, polypharmacy has become a serious public health issue worldwide. Although acute renal failure (ARF) is one negative consequence of polypharmacy, the association between the duration of polypharmacy and ARF remains unclear. We therefore assessed this association using a population-based database.

METHODS

Data were collected from the Taiwan National Health Insurance Research Database (NHIRD) from 2003 through 2006. The case group included patients hospitalized for ARF during 2006, but not admitted due to trauma, surgery, burn trauma, car accident, transplantation, or infectious diseases; the control group included patients hospitalized without ARF. The cumulative number of days of polypharmacy (defined as more than 5 prescriptions per day) for 1 year prior to admission was determined, with patients further subdivided into 4 categories: less than 30 days, 31-90 days, 91-180 days, and over 181 days. The dependent variable was ARF, and the control variables were age, gender, comorbidities in patients hospitalized for ARF, stay in ICUs during ARF hospitalization and site of operation for prior admissions within one month of ARF hospitalization.

RESULTS

Of 20,790 patients who were admitted to hospitals for ARF in 2006, 12,314 (59.23 %) were male and more than 60 % were older than 65 years. Of patients with and without ARF, 16.14 % and 10.61 %, respectively, received polypharmacy for 91-180 days and 50.22 % and 24.12 %, respectively, for over 181 days. A statistical model indicated that, relative to patients who received polypharmacy for less than 30 days, those who received polypharmacy for 31-90, 91-180 and over 181 days had odds ratios of developing ARF of 1.33 (p<0.001), 1.65 (p<0.001) and 1.74 (p<0.001), respectively.

CONCLUSIONS

We observed statistically significant associations between the duration of polypharmacy and the occurrence of ARF.

Acute renal failure in the elderly: particular characteristics

Elderly individuals comprise the faster growing patient population group and acute renal failure (ARF) is quite common among them, although exact numbers are not known. We reviewed the literature with regards to the characteristics of ARF in elderly patients and describe some useful guidelines. The ageing kidney is characterized by many structural and functional changes, which are mainly due to various chronic disorders, such as hypertension, diabetes and atherosclerosis, which are highly prevalent in these patients. A number of structural and functional changes characteristic of the ageing kidney make elderly people especially prone to renal damage. ARF in the elderly is frequently of multifactorial origin and often with an atypical presentation, like the "intermediate syndrome", which combines characteristics of pre-renal azotemia and acute tubular necrosis. Physical examination and laboratory blood and urine indices may sometimes be misleading occasionally leading to misdiagnosis. Prophylaxis remains the preferred approach to therapy: one should avoid nephrotoxic drugs and poly-pharmacy, adjust drug doses and achieve adequate hydration of the patient as cautiously as possible. Dialysis therapies can be used for treatment of ARF irrespective of age and carry a good prognosis.