How do I manage acute kidney injury (AKI) in a patient with sepsis and shock due to pneumonia, who has a history of obesity, hypertension (HTN), heart disease (HD), diabetes mellitus type 2 (DM2), and chronic obstructive pulmonary disease (COPD)?

Management of AKI in Septic Shock from Pneumonia

Immediately initiate aggressive fluid resuscitation with at least 30 mL/kg of isotonic crystalloids within 3 hours, start norepinephrine as first-line vasopressor to maintain MAP ≥65 mmHg, and administer broad-spectrum antibiotics within 1 hour—prioritizing survival over concerns about nephrotoxicity or volume overload. 1, 2, 3

Immediate Hemodynamic Resuscitation

Fluid Management:

• Administer at least 30 mL/kg of isotonic crystalloids (normal saline or lactated Ringer's) within the first 3 hours targeting MAP ≥65 mmHg 1, 2
• Use crystalloids exclusively—avoid albumin and hydroxyethyl starches as they worsen AKI outcomes and provide no survival benefit 4, 2
• Once hemodynamically stable, avoid overzealous continued fluid administration as volume overload worsens both renal and overall outcomes 1, 2

Vasopressor Support:

• Initiate norepinephrine as the first-line vasopressor when MAP remains <65 mmHg despite fluid resuscitation 4, 1, 2
• Norepinephrine is superior to dopamine, which increases arrhythmias and mortality in septic shock 4
• Vasopressin (up to 0.03 U/min) can be added to norepinephrine if additional support is needed, but should not be used as sole initial agent 4, 1
• Target MAP ≥65 mmHg, though this patient's history of hypertension may require individualized higher targets (MAP 70-75 mmHg) to maintain adequate renal perfusion 4

Source Control and Antimicrobial Therapy

• Obtain blood cultures and initiate broad-spectrum antibiotics within 1 hour of septic shock recognition 1, 2, 3
• Do not withhold or delay antibiotics due to nephrotoxicity concerns—survival benefit from treating sepsis outweighs AKI risk 1, 2
• If vancomycin is indicated for MRSA coverage, initiate immediately despite AKI; ensure adequate resuscitation before attributing worsening renal function to vancomycin 1
• Given COPD history, cover for typical and atypical pneumonia pathogens plus Pseudomonas 3

Renal Replacement Therapy Decision-Making

Initiate RRT only for definitive indications: 1, 2

• Severe metabolic acidosis (pH <7.15)
• Hyperkalemia refractory to medical management
• Uremic complications (pericarditis, encephalopathy, bleeding)
• Refractory volume overload causing pulmonary edema

Do not initiate RRT solely for: 1, 2

• Elevated creatinine without other indications
• Oliguria alone
• Arbitrary BUN thresholds

Modality Selection:

• Use continuous renal replacement therapy (CRRT) rather than intermittent hemodialysis in this hemodynamically unstable patient to facilitate fluid balance management during ongoing resuscitation 1, 2

Metabolic and Glycemic Management

Blood Glucose Control:

• Target blood glucose ≤180 mg/dL using protocolized insulin therapy 4, 1, 2
• Avoid tight glycemic control (110-149 mg/dL or lower) in this diabetic patient with likely poor baseline control, as rapid correction worsens outcomes 4
• Monitor glucose every 1-2 hours until stable, then every 4 hours 2

Acid-Base Management:

• Do not administer sodium bicarbonate to improve hemodynamics or reduce vasopressor requirements if pH ≥7.15 1, 2
• Bicarbonate does not improve outcomes and may worsen intracellular acidosis 1

Nutritional Support

• Initiate early enteral nutrition (preferentially over parenteral) within 48 hours if tolerated 4, 1
• Target 20-30 kcal/kg/day total energy intake 4, 1
• Provide protein based on RRT status: 4, 1
  • 0.8-1.0 g/kg/day if not on dialysis
  • 1.0-1.5 g/kg/day if on RRT
  • Up to 1.7 g/kg/day if on CRRT or hypercatabolic
• Do not restrict protein to delay RRT initiation—this patient is likely hypercatabolic and requires adequate protein 4

Nephrotoxin Avoidance

• Each additional nephrotoxin increases AKI odds by 53%; combining 3+ nephrotoxins doubles AKI risk 1
• Avoid NSAIDs completely 1
• Avoid aminoglycosides unless no alternative exists for resistant organisms 4, 1
• Avoid contrast agents unless absolutely necessary 4, 1
• Adjust all renally-cleared medications for decreased GFR 1

Supportive Care Measures

VTE Prophylaxis:

• Administer pharmacologic VTE prophylaxis with low-molecular-weight heparin (LMWH) unless contraindicated 1, 2
• Switch to unfractionated heparin if creatinine clearance <30 mL/min 2

Stress Ulcer Prophylaxis:

• Provide proton pump inhibitor or H2-receptor antagonist given mechanical ventilation risk and coagulopathy risk in septic shock 1

Monitoring Parameters

• Serial creatinine and urine output every 4-6 hours 1
• Lactate clearance as marker of adequate resuscitation 1
• Fluid balance assessment every 4-6 hours 1
• SOFA score daily to track organ dysfunction progression 3

Critical Pitfalls to Avoid

• Do not under-resuscitate due to fear of volume overload—inadequate initial resuscitation worsens both sepsis-associated AKI and mortality 2
• Do not use dopamine as first-line vasopressor—it increases arrhythmias and mortality compared to norepinephrine 4
• Do not delay antibiotics for any reason including concern about nephrotoxicity 1, 2
• Do not use colloids (albumin, starches) for resuscitation—they increase AKI risk without improving outcomes 4, 2
• Given this patient's obesity, ensure weight-based dosing uses actual body weight for initial fluid resuscitation but adjusted body weight for medication dosing 1