What is the difference between sepsis and septic shock in a postoperative patient with a history of kidney disease?

Sepsis vs Septic Shock: Key Distinctions

Septic shock is a subset of sepsis characterized by profound circulatory and metabolic abnormalities requiring vasopressors to maintain MAP ≥65 mmHg plus lactate >2 mmol/L despite adequate fluid resuscitation, with mortality exceeding 40% compared to sepsis alone. 1, 2

Defining Sepsis

Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, operationalized as an increase in Sequential Organ Failure Assessment (SOFA) score of 2 points or more, associated with in-hospital mortality >10%. 1, 2

Clinical Recognition

• Bedside screening (qSOFA): Identify patients with suspected infection who have ≥2 of the following: 2
  • Respiratory rate ≥22/min
  • Altered mental status
  • Systolic blood pressure ≤100 mmHg
• These criteria indicate poor outcomes typical of sepsis and warrant immediate escalation of care 2

Defining Septic Shock

Septic shock represents particularly profound circulatory, cellular, and metabolic abnormalities with substantially higher mortality risk than sepsis alone. 1, 2

Diagnostic Criteria (Both Required)

• Vasopressor requirement to maintain mean arterial pressure ≥65 mmHg 1, 2
• Serum lactate >2 mmol/L (>18 mg/dL) in the absence of hypovolemia 1, 2
• This combination carries hospital mortality rates >40% 2

Mortality Stratification

The progression from infection to septic shock demonstrates escalating mortality risk: 1

• No sepsis: 1.2% mortality
• Sepsis only: 4.4% mortality
• Severe sepsis (now obsolete term): 27.8% mortality
• Septic shock: 67.8% mortality

This dramatic mortality gradient underscores why distinguishing septic shock from sepsis is clinically critical for prognostication and resource allocation. 1

Special Considerations in Postoperative Patients with Kidney Disease

Heightened Vulnerability

• Postoperative patients with kidney disease face atypical presentations with non-specific clinical signs that can delay recognition 1
• Pre-existing renal dysfunction complicates SOFA score interpretation, as baseline creatinine may already be elevated 1
• These patients have increased risk for multidrug-resistant organisms and Candida infections 1

Vasopressor Paradox in Renal Disease

• While vasopressors are mandatory to maintain MAP ≥65 mmHg in septic shock, they paradoxically increase renal vascular resistance and can worsen AKI 3
• Norepinephrine is the first-line vasopressor, superior to dopamine which increases mortality in septic shock 1
• This creates a clinical dilemma where life-saving hemodynamic support may simultaneously injure the kidneys 3

Fluid Management Pitfalls

• Initial resuscitation requires ≥30 mL/kg crystalloid within 3 hours 4
• However, avoid fluid overload in postoperative peritonitis patients, as this aggravates bowel edema, increases intra-abdominal pressure, and can precipitate abdominal compartment syndrome 1
• Target MAP 65-70 mmHg as the hemodynamic endpoint rather than arbitrary fluid volumes 1

Antibiotic Considerations

• Immediate appropriate antibiotics take priority over nephrotoxicity concerns 4
• Each additional nephrotoxic agent increases AKI odds by 53%, and combining ≥3 nephrotoxins doubles AKI risk 4
• Balance aggressive antimicrobial therapy against cumulative nephrotoxic burden, particularly with vancomycin and aminoglycosides 5

Long-Term Renal Outcomes

• Even stage 1 AKI in septic shock carries 10% risk of progression to chronic kidney disease at one year 6
• Risk factors for CKD development include older age, female sex, diabetes, low hemoglobin, and elevated creatinine at discharge 6
• AKI severity correlates with mortality but not necessarily with CKD progression, meaning even mild AKI warrants careful follow-up 6

Critical Action Points

Early recognition and immediate intervention are paramount: 7

• Initiate fluid resuscitation and vasopressors without delay when septic shock criteria are met 1, 4
• Source control and appropriate antimicrobials cannot be delayed for diagnostic certainty 4
• Monitor for organ dysfunction progression using SOFA scoring 2
• In patients with kidney disease, balance aggressive resuscitation against fluid overload and nephrotoxin exposure 1, 4