Updates in Management and Timing of Dialysis in Acute Kidney Injury

All patients with AKI should have close monitoring of their serum creatinine and urine output. Noninvasive diagnostic studies (urine microscopy, postvoid residual, and renal ultrasound) should be considered based on the clinical scenario. General management strategies include treatment of the reversible causes of AKI and optimization of volume status, hemodynamics, and nutritional status (Table 2).

Reversible Causes of Acute Kidney Injury

The first step in the treatment of AKI is to identify and treat readily reversible causes of AKI such as volume depletion, hypotension, infection, and urinary obstruction. Nephrotoxins should be avoided and all medications should be reviewed and adjusted for kidney function, particularly those that may affect mental status. Avoid opiates with noxious or active metabolites, including meperidine and morphine. Instead, hydromorphone, fentanyl, and methadone are preferred in patients with AKI. Other commonly used medications that require dose adjustment include gabapentin, baclofen, metoclopramide, H2 antagonists, many commonly prescribed antibiotics (penicillins, most cephalosporins, carbapenems, quinolones, and sulfa drugs), many hypoglycemic agents, and insulin. For patients on RRT, dosing is dependent on dialysis modality. Consultation with a hospital pharmacist is recommended when RRT modalities are initiated or changed.

Intravenous Fluids

Patients with AKI should have their volume status assessed and receive adequate resuscitation with intravenous fluids to promote renal perfusion. However, the optimal type and volume of fluid to give in AKI remains controversial. Colloid-containing solutions are theoretically confined to the intravascular space and should pose a lower risk for pulmonary edema compared with crystalloids. However, these solutions are costly, are not associated with any meaningful benefit,^20-22 and may even be associated with potential harm.^22-27

The most commonly used colloid worldwide is hydroxyethyl starch (HES). Its potential adverse effects include anaphylactoid reactions, coagulopathy, and AKI. HES is cleared by the kidneys and can cause osmotic nephrosis, a form of AKI characterized by vacuole formation and proximal renal tubular damage.²⁸ Randomized controlled trials have shown an increased risk of AKI, RRT use, and mortality in critically ill patients who were resuscitated with HES.^22,26,27 HES is not currently recommended in patients who are critically ill or have impaired kidney function and sepsis guidelines advise against its use.²⁹

In the United States, albumin is the most common colloid-containing solution used for intravascular volume resuscitation. Albumin has been shown to be safe for volume resuscitation in critically ill patients,²⁰ but there is no proven advantage to using albumin over saline with respect to mortality, length of hospital stay, duration of mechanical ventilation, duration of RRT, or number of organ systems failure.^20,21 Furthermore, albumin may be harmful in certain patient populations. In patients with traumatic brain injury, albumin resuscitation is associated with higher mean intracranial pressures²³ and long-term mortality.²⁴ In a retrospective study of patients undergoing cardiac surgery, albumin administration was associated with more than twice the risk of AKI compared with crystalloids.²⁵ In contrast, in patients with cirrhosis, intravenous albumin lowers the rate of AKI when administered in the setting of a large volume paracentesis³⁰ or spontaneous bacterial peritonitis.³¹ Outside of these narrow settings, current evidence does not support the use of intravenous albumin to prevent AKI and we would not endorse the use of intravenous albumin as a part of the treatment paradigm for established AKI.

Many renal and critical care guidelines recommend initial fluid resuscitation with isotonic crystalloids except in specific circumstances (ie, hemorrhagic shock), with consideration of albumin in select cases (ie, severe sepsis or cirrhosis).^16,18,19,29 That stated, the optimal type of crystalloid solution that should be used in resuscitation remains unclear. Because of its low cost, normal (0.9%) saline is the most commonly used solution, but it can result in hyperchloremic metabolic acidosis, which can cause renal vasoconstriction and may be associated with mortality in critically ill patients.³² A prospective study found that administration of chloride-liberal fluids (including normal saline) to critically ill patients was associated with nearly twice the risk of AKI and RRT use compared with chloride-restrictive fluids,³³ but a subsequent trial found no difference in AKI or mortality among patients receiving saline versus a balanced crystalloid (Plasma-Lyte 148).³⁴ A recent pair of large, randomized control trials compared outcomes in patients at a single center who were resuscitated with normal saline versus balanced crystalloid solutions (Lactated Ringer’s or Plasma-Lyte A).^35,36 In critically ill patients, the use of balanced crystalloid solutions was associated with a lower risk of the composite outcome of mortality, new RRT, or persistent kidney impairment, but there were no differences in any of the individual components of the composite outcome.³⁵ In noncritically ill patients, there were no differences in the number of hospital-free days based on the type of crystalloid solution used.³⁶ In the absence of compelling evidence for using balanced crystalloid solutions, we continue to use normal saline for initial fluid resuscitation, but to avoid severe hyperchloremia and acidosis, we will consider switching to a balanced solution (Lactated Ringer’s, Plasma-Lyte, or Normosol) for large volume resuscitation (>2 L), particularly in critically ill patients.