How to manage acute kidney injury (AKI) in patients with intracranial hemorrhage (ICH)?

Management of Acute Kidney Injury in Patients with Intracranial Hemorrhage

In ICH patients who develop AKI, prioritize ICH-directed care first—specifically blood pressure management targeting 130-140 mmHg—while simultaneously addressing AKI through discontinuation of nephrotoxic agents and preferential use of continuous renal replacement therapy if dialysis becomes necessary. 1

Understanding the Relationship Between ICH and AKI

The development of AKI in ICH patients primarily reflects overall critical illness severity rather than ICH-specific mechanisms. 1 The incidence ranges from 9-10.5% in hospitalized ICH patients, with most cases being mild (stage 1 AKI in 67.69% of affected patients). 2, 3

Key Risk Factors to Identify

• APACHE II score is an independent predictor (OR: 1.846,95% CI: 1.319-2.585). 3
• Diabetes mellitus increases risk substantially (OR: 3.609,95% CI: 1.596-8.163). 3
• Mannitol infusion rate ≥1.34 g/kg/day is strongly associated with AKI (OR: 3.495,95% CI: 1.910-3.395). 3, 4
• Age ≥70 years independently predicts AKI development. 4
• Diastolic blood pressure ≥110 mm Hg at presentation increases risk. 4
• Pre-existing renal dysfunction (GFR <60 ml/min/1.73 m²) predisposes to AKI. 4
• Larger hematoma volumes correlate with higher AKI incidence. 5

Blood Pressure Management: The Critical Priority

Target Blood Pressure Parameters

For ICH patients with SBP 150-220 mmHg and mild-to-moderate severity, target systolic blood pressure of 130-140 mmHg, initiating treatment within 2 hours of onset and reaching target within 1 hour. 6, 1

• Use IV nicardipine or other rapid-onset, short-duration agents to minimize blood pressure variability, which independently predicts poor outcomes. 6, 1
• Never lower SBP below 130 mmHg, as this is potentially harmful. 6, 1
• Monitor blood pressure every 15 minutes until stabilized, then every 30-60 minutes for the first 24-48 hours. 6
• Ensure smooth, sustained control avoiding peaks and large variability in SBP. 6

Balancing BP Reduction with Renal Perfusion

While aggressive blood pressure reduction is essential for ICH management, be aware that the area under the curve for 24-hour systolic blood pressure and higher average maximum hourly nicardipine doses show strong association with stage I renal impairment. 2 However, this concern does not override the established benefit of blood pressure control in ICH—rather, it mandates careful renal function monitoring during treatment. 2

Immediate AKI Management Strategies

Medication Adjustments

Discontinue all nephrotoxic agents immediately: 1

• NSAIDs increase AKI risk more than twofold in volume-depleted patients. 1
• Withdraw diuretics to prevent exacerbation of prerenal AKI. 1
• Hold ACE inhibitors and ARBs to avoid further reduction in glomerular filtration. 1

Mannitol Management

Given that mannitol infusion rate ≥1.34 g/kg/day is an independent risk factor for AKI (with higher rates causing more severe AKI), strictly limit mannitol to <1.34 g/kg/day when osmotic therapy is required. 3, 4 Monitor renal function frequently in patients receiving mannitol, as the incidence and severity of AKI increases with higher infusion rates. 4

Contrast Agent Considerations

While CT angiography is recommended for most ICH patients to exclude underlying vascular lesions, 6 recognize that contrast exposure contributes to AKI risk, though one study found similar AKI rates regardless of contrast exposure, suggesting overall medical status drives kidney injury more than contrast itself. 1

Renal Replacement Therapy Decision-Making

Indications for RRT Initiation

Initiate RRT emergently when metabolic and fluid demands exceed kidney capacity, specifically for: 6

• Severe hyperkalemia with ECG changes
• Severe metabolic acidosis with impaired respiratory compensation
• Pulmonary edema unresponsive to diuretics
• Uremic complications (encephalopathy, pericarditis, bleeding)
• Severe symptomatic dysnatremia resistant to medical management

Modality Selection in ICH Patients

Prefer continuous RRT (CRRT) over intermittent hemodialysis in hemodynamically unstable ICH patients, as both modalities can cause changes in intracranial pressure, but the risk is higher with intermittent hemodialysis. 6, 1 CRRT produces lower fluid shifts and reduced hemodynamic instability. 1

For hemodynamically stable ICH patients requiring RRT, intermittent hemodialysis is acceptable, but modality transition from CRRT to intermittent hemodialysis should only occur when vasopressor support has been stopped, intracranial hypertension has resolved, and positive fluid balance can be controlled. 6

CRRT Prescription Parameters

• Effluent dose: 20-25 ml/kg/hour. 6
• Modality: CVVHDF preferred. 6
• Anticoagulation: Regional citrate anticoagulation if no contraindications. 6
• Replacement fluid: Bicarbonate-based. 6

Vascular Access

Use uncuffed non-tunneled dialysis catheter with preferred sites in order: 6

1. Right internal jugular vein
2. Femoral vein
3. Left internal jugular vein
4. Subclavian vein (last choice due to stenosis risk)

Neurological Monitoring During AKI Management

Assessment Frequency

• Assess neurological status frequently using NIHSS for awake/drowsy patients or Glasgow Coma Scale for obtunded patients. 6
• Conduct validated neurological scale (such as CNS score) at baseline and repeat at least hourly for the first 24 hours. 6
• Monitor for clinical signs of increased intracranial pressure. 6

Intracranial Pressure Considerations

While there is insufficient evidence from RCTs to make strong recommendations on specific measures to lower intracranial pressure, 6 recognize that both continuous and intermittent RRT can lead to changes in ICP, with higher risk during intermittent hemodialysis. 6 This reinforces the preference for CRRT in ICH patients requiring dialysis.

Critical Care Setting

Admit all ICH patients with AKI to a neuroscience intensive care unit or stroke unit rather than a general ICU, as admission to specialized units may result in reduced mortality rates. 6 These units provide specialized multidisciplinary care with vascular neurology expertise and protocols for monitoring neurological deterioration. 7

Common Pitfalls to Avoid

• Never delay ICH-specific interventions to pursue AKI workup or treatment—ICH management takes absolute priority. 1
• Do not perform lumbar puncture before neuroimaging in patients with suspected elevated ICP, as this can precipitate herniation. 1
• Avoid aggressive BP lowering below 130 mmHg despite AKI concerns, as this worsens ICH outcomes. 6, 1
• Do not use intermittent hemodialysis in hemodynamically unstable patients with ICH due to increased ICP fluctuation risk. 6
• Monitor renal function carefully when administering blood pressure reduction, as systolic blood pressure reduction parameters show association with renal impairment. 2

Monitoring Protocol

• Electrolytes and acid-base status: Every 2-4 hours initially. 8
• Hourly vital signs: Assess for hypotension during dialysis. 8
• Pre- and post-dialysis weights: Monitor fluid balance. 8
• Urine output: Monitor if any residual function present. 8
• Renal recovery assessment: Weekly pre-dialysis creatinine and residual kidney function if dialysis continues beyond 14 days. 8