From the Guidelines

In patients with hypertensive emergency and acute kidney injury (AKI), fluid administration is recommended to optimize renal perfusion 1.

The choice of fluid is crucial, with isotonic crystalloids (such as 0.9% saline or lactated Ringer's solution) being preferred over colloids (albumin or starches) for initial management of expansion of intravascular volume in patients at risk for AKI or with AKI 1.
A bolus of 500-1000 mL of 0.9% saline or lactated Ringer's solution may be given over 30 minutes to 1 hour, with subsequent infusion rates titrated to maintain a urine output of at least 0.5 mL/kg/hour.
It is essential to consider the patient's volume status and urine flow when determining the amount of fluid to administer, as hypotension, bleeding, and third spacing suggest hypovolemia, requiring more fluid administration, while signs of fluid overload, especially in anuria, indicate the need for less fluid 1.
Additionally, medications such as fenoldopam (at a dose of 0.1-0.3 mcg/kg/minute) or dopamine (at a dose of 1-2 mcg/kg/minute) may be considered to enhance renal blood flow and function, although their use should be guided by the patient's specific clinical context and the presence of other comorbidities 1.

From the Research

The management of hypertensive emergencies is directed at the specific situation, with the rate and extent of blood pressure lowering tailored to the type and extent of organ damage 2.
In patients with AKI, fluid administration may increase renal perfusion, but its effects are quite unpredictable and can be dissociated from its impact on cardiac output and arterial pressure 3.
The optimal mean arterial pressure (MAP) target level remains undefined, and it is reasonable to individualize MAP target, paying attention to central venous and intraabdominal pressures, as well as to the response to an increase in MAP 3.
There is no direct evidence to recommend fluid administration in patients with hypertensive emergency and AKI, but fluid withdrawal should be considered at the de-escalation phase, and safe fluid withdrawal may be achieved when applied in selected patients with preserved tissue perfusion presenting signs of fluid intolerance 3.

A hypertensive crisis is defined as a sudden and significant rise in blood pressure, and it can lead to a heart attack, stroke, or other life-threatening medical problems 4.
The treatment of acute severe hypertension varies according to the hospital unit, medication, and blood pressure targets or thresholds, and arbitrary blood pressure control targets are used, or blood pressure targets are crudely extrapolated from guidelines intended primarily for outpatient management 4.
Patients with acute aortic dissection need to be administered intravenous esmolol within 5 to 10 minutes to lower their blood pressure right away, and the goal is to maintain a systolic reading of less than 120 mm Hg 4.

The management of hypertensive emergencies represents a clinical challenge due to the lack of ad hoc randomized clinical trials, and current recommendations/suggestions for treatment are not evidence-based 5.
A symptoms- and evidence-based streamlined algorithm for the assessment and treatment of patients with hypertensive emergencies has been proposed, which includes a quick identification of hypertensive emergencies and associated acute organ damage 5.
The use of intravenous medications in hospitalized hypertensive patients without organ dysfunction is common, and IV medication use was associated with higher comorbidity burden, prior kidney disease, and longer length of stay 6.