Lactate
Related Subjects:
|Respiratory Failure
|Non-invasive ventilation (NIV)
|Intubation and Mechanical Ventilation
|Critical illness neuromuscular weakness
|Haemodialysis
|Dobutamine
📖 About Lactate
- 🧬 Lactate is produced as a by-product of anaerobic respiration, especially when oxygen supply is insufficient for metabolic demands.
- ⚡ When tissues switch to anaerobic metabolism, lactate accumulates → marker of poor tissue oxygenation.
- 📊 Commonly measured in acutely ill patients (esp. sepsis, shock, trauma). Elevation signals tissue hypoperfusion but can also be due to metabolic, toxic, or pharmacological causes.
- 📈 No single universal definition of “raised lactate”: many use ≥2.0–2.5 mmol/L; severe hyperlactataemia usually >4 mmol/L.
- ☠️ Prognosis worsens with higher lactate. Example (post-cardiac arrest):
- <5 mmol/L → ~39% mortality
- >10 mmol/L → ~92% mortality
🚨 Causes of Raised Lactate
- Shock states: 🩸 distributive (sepsis), cardiogenic, hypovolaemic, obstructive (e.g., PE, tamponade), post–cardiac arrest.
- Medications: 💊 Linezolid, NRTIs (HIV therapy), Metformin, Epinephrine, Propofol, Paracetamol, β2 agonists, Theophylline.
- Regional ischaemia: 🦵 mesenteric ischaemia, limb ischaemia, burns, trauma, compartment syndrome, necrotising fasciitis, seizures, excessive exercise, ↑ work of breathing.
- Metabolic disorders: 🍬 diabetic ketoacidosis, mitochondrial disease, thiamine deficiency.
- Toxins: 🍷 alcohols, cocaine, cyanide, CO poisoning.
- Malignancy: 🧫 tumour hypoxia and ↑ metabolic demand.
- Liver failure: 🟤 reduced clearance → accumulation.
🧴 Mnemonic: SHAMPOO for Lactate Causes
- Shock (septic, cardiogenic, hypovolaemic, obstructive)
- Hypoxia / hypoperfusion
- Anaerobic exercise / seizures
- Metformin & other medications (linezolid, propofol, etc.)
- Poisons (alcohols, cyanide, carbon monoxide, cocaine)
- Obstruction / ischaemia (mesenteric, limb, compartment syndrome)
- Organ failure (esp. liver failure)
🧾 Key Reference
💡 Exam Tips
- Think shock + sepsis first in acute care 🔥.
- Always ask: is it due to overproduction (hypoxia, sepsis, seizures) vs under-clearance (liver failure)?
- Serial lactates 📉 are more useful than a single measurement → track perfusion and response to therapy.
