Does administering intravenous (IV) fluid reduce the risk of renal complications?

Does IV Fluid Reduce Renal Complications Risk?

Yes, appropriate IV fluid administration reduces renal complications, but the type, volume, and timing are critical—both inadequate resuscitation and excessive fluid overload increase acute kidney injury (AKI) risk.

Optimal Fluid Strategy for Renal Protection

Volume Management: The Critical Balance

Aim for a mildly positive fluid balance (+1-2 L by end of procedure/day) rather than zero-balance or aggressive hydration to protect kidney function. 1

• A large multicenter RCT in 3,000 patients undergoing major abdominal surgery found significantly higher AKI incidence with restrictive "zero-balance" fluid regimens compared to modestly liberal regimens (body weight increase of 1.6 kg vs 0.3 kg in first 24 hours) 1
• However, aggressive fluid administration (>5 L/day) increases mortality (RR 2.42) and fluid-related complications (RR 2.49) compared to moderate regimens 1
• Both hypovolemia and fluid overload cause organ dysfunction and AKI—the goal is maintaining intravascular euvolemia in the "green zone" 1

Fluid Type: Buffered Crystalloids Are Superior

Use buffered (balanced) crystalloid solutions rather than 0.9% saline to reduce AKI risk. 1

• Large volumes of 0.9% saline cause hyperchloraemic acidosis, renal vasoconstriction, and AKI 1
• The SALT trial and subsequent large RCT (15,802 critically ill patients) demonstrated buffered crystalloids were associated with lower rates of major adverse kidney events (MAKE: composite of death, need for renal replacement therapy, and persistent renal dysfunction) compared to 0.9% saline 1
• A propensity-matched cohort study of 22,851 surgical patients showed hyperchloraemia (present in ~20% receiving saline) was associated with increased 30-day mortality 1
• Balanced solutions reduce hyperchloremic acidosis and kidney injury risk compared to saline 1, 2

In kidney transplantation specifically, buffered crystalloids strongly reduce delayed graft function risk compared to 0.9% saline. 1

Colloids: Avoid in Most Situations

Do not routinely use albumin or synthetic colloids (including hydroxyethyl starches) for fluid administration—they increase AKI risk without mortality benefit. 1

• Hydroxyethyl starches increase severe AKI risk in general and septic ICU patients 3
• The FLASH study showed significantly more renal failure with HES (RR 1.34, p=0.05) 1
• Meta-analyses show no mortality benefit from colloids over crystalloids, with increased risk of renal replacement therapy 1
• HES also causes haemostasis disorders and increased bleeding 1

Context-Specific Protocols

Contrast-Induced AKI Prevention

Administer IV volume expansion with either isotonic sodium chloride or sodium bicarbonate (not oral fluids alone) before contrast procedures in high-risk patients. 1

• Target urinary flow rates >150 ml/h for 6 hours post-procedure 1
• Typical protocol: 1.5 ml/kg/h of isotonic fluid, or 3 ml/kg over 1 hour pre-procedure followed by 1 ml/kg/h for 6 hours post-procedure 1
• Isotonic bicarbonate does not appear to offer significant advantage over isotonic saline, but is not inferior 1
• Patients must not be fluid restricted pre-procedure 1

Perioperative Setting

For elective surgery, use buffered crystalloids at rates achieving mildly positive balance, avoiding both restrictive zero-balance and aggressive protocols. 1

• Restrictive regimens increase AKI but reduce other complications 1
• Aggressive regimens (20 ml/kg bolus then 3 ml/kg/hr) increase mortality without benefit 1
• Moderate approach (10 ml/kg bolus then 1.5 ml/kg/hr with goal-directed adjustments) provides optimal balance 1

Critical Illness and Sepsis

In critically ill patients with or at risk of AKI, avoid starch solutions and preferentially use buffered crystalloids over saline. 3, 2

• Volume resuscitation is needed to restore cardiac output initially 4, 2
• Once hemodynamic stabilization is achieved, switch to neutral then negative balance to avoid fluid overload 4
• Conservative fluid strategies after initial resuscitation improve outcomes 4
• Fluid overload predisposes to organ dysfunction, impaired wound healing, and nosocomial infection 4

Critical Pitfalls to Avoid

Do not continue aggressive fluid administration beyond initial resuscitation—fluid overload delays renal recovery and increases mortality. 4, 2

• Salt and water overload impairs excretion in AKI patients, creating vicious cycle 4
• Interstitial edema from fluid overload further delays renal recovery 4
• Conservative strategies may require earlier renal replacement therapy but improve overall outcomes 4

Do not use 0.9% saline as the primary resuscitation fluid—it directly causes renal vasoconstriction. 1, 3

• Experimental studies show saline infusion reduces renal perfusion compared to buffered solutions 3
• The dose-response relationship means larger volumes cause more harm 1

Avoid hydroxyethyl starches entirely in critically ill patients—they consistently increase AKI and renal replacement therapy requirements. 1, 3

Monitoring Requirements

Assess fluid responsiveness using dynamic preload indexes (stroke volume variation, pulse pressure variation) rather than static pressures (CVP). 2

• Passive leg-raising test and end-expiratory occlusion test are more reliable than central venous pressure 2
• Accurate assessment of intravascular volume status is essential to avoid both hypovolemia and overload 2
• In established AKI unresponsive to fluids, fluid restriction becomes the treatment of choice 2