What is a sign of early sepsis?

Respiratory Alkalosis is a Sign of Early Sepsis

The correct answer is (c) respiratory alkalosis, which is one of the earliest respiratory manifestations of sepsis. 1

Pathophysiological Basis

Respiratory alkalosis occurs in early sepsis due to:

• Centrally mediated hyperventilation triggered by inflammatory mediators and cytokines 1
• Increased respiratory rate (≥22/min), which is a diagnostic criterion for sepsis 2, 1
• Increased elimination of CO2, resulting in decreased PaCO2 levels and elevated pH 1

Progression of Acid-Base Disturbances in Sepsis

The acid-base disturbances in sepsis typically follow a progression:

1. Early sepsis: Respiratory alkalosis (increased respiratory rate, decreased PaCO2, elevated pH) 1
2. Progressive sepsis: Metabolic acidosis develops due to:
   • Lactic acidosis from tissue hypoperfusion
   • Hyperchloremic acidosis
   • Renal dysfunction 1

Clinical Significance of Respiratory Alkalosis in Sepsis

Recognizing respiratory alkalosis as an early sign of sepsis is crucial because:

• It may be present before other clinical manifestations become apparent 1
• Waiting for metabolic acidosis to develop may delay diagnosis and treatment 1
• Early intervention based on respiratory changes can improve outcomes 1

Other Early Signs of Sepsis

In addition to respiratory alkalosis, other early signs of sepsis include:

• Tachycardia (heart rate >90 beats/min) 2, 1
• Temperature abnormalities (>38.3°C or <36°C) 2, 1
• Altered mental status 1
• Systolic blood pressure ≤100 mmHg 1
• Oliguria (<0.5 mL/kg/hour) 1

Why Other Options are Incorrect

• (a) Metabolic alkalosis: Not typically associated with sepsis; occurs in other conditions like vomiting or diuretic use
• (b) Metabolic acidosis: Develops in later stages of sepsis as tissue perfusion worsens and lactate accumulates 1
• (d) Respiratory acidosis: Contrary to the hyperventilation pattern seen in early sepsis; may occur very late if respiratory muscles fatigue or in severe ARDS

Clinical Implications

• Blood gas analysis showing respiratory alkalosis in a patient with suspected infection should raise concern for early sepsis 1
• Early recognition allows for timely implementation of sepsis bundles, including:
  • Obtaining cultures before antibiotic administration
  • Administering broad-spectrum antibiotics within one hour
  • Initiating fluid resuscitation (30 mL/kg crystalloids) for hypotension or elevated lactate 1

Common Pitfalls

• Failing to recognize tachypnea as a significant vital sign abnormality in patients with suspected infection
• Waiting for metabolic acidosis or other late signs before initiating sepsis protocols
• Not obtaining arterial blood gases in patients with increased respiratory rate and suspected infection

Understanding that respiratory alkalosis is an early sign of sepsis allows for more timely recognition and intervention, potentially improving patient outcomes in this life-threatening condition.