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2025 PACUPrep BCCCP Preparatory Course

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  1. Pulmonary

    ARDS
    4 Topics
    |
    1 Quiz
  2. Asthma Exacerbation
    4 Topics
    |
    1 Quiz
  3. COPD Exacerbation
    4 Topics
    |
    1 Quiz
  4. Cystic Fibrosis
    6 Topics
    |
    1 Quiz
  5. Drug-Induced Pulmonary Diseases
    3 Topics
    |
    1 Quiz
  6. Mechanical Ventilation Pharmacotherapy
    5 Topics
    |
    1 Quiz
  7. Pleural Disorders
    5 Topics
    |
    1 Quiz
  8. Pulmonary Hypertension (Acute and Chronic severe pulmonary hypertension)
    5 Topics
    |
    1 Quiz
  9. Cardiology
    Acute Coronary Syndromes
    6 Topics
    |
    1 Quiz
  10. Atrial Fibrillation and Flutter
    6 Topics
    |
    1 Quiz
  11. Cardiogenic Shock
    4 Topics
    |
    1 Quiz
  12. Heart Failure
    7 Topics
    |
    1 Quiz
  13. Hypertensive Crises
    5 Topics
    |
    1 Quiz
  14. Ventricular Arrhythmias and Sudden Cardiac Death Prevention
    5 Topics
    |
    1 Quiz
  15. NEPHROLOGY
    Acute Kidney Injury (AKI)
    5 Topics
    |
    1 Quiz
  16. Contrast‐Induced Nephropathy
    5 Topics
    |
    1 Quiz
  17. Drug‐Induced Kidney Diseases
    5 Topics
    |
    1 Quiz
  18. Rhabdomyolysis
    5 Topics
    |
    1 Quiz
  19. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
    5 Topics
    |
    1 Quiz
  20. Renal Replacement Therapies (RRT)
    5 Topics
    |
    1 Quiz
  21. Neurology
    Status Epilepticus
    5 Topics
    |
    1 Quiz
  22. Acute Ischemic Stroke
    5 Topics
    |
    1 Quiz
  23. Subarachnoid Hemorrhage
    5 Topics
    |
    1 Quiz
  24. Spontaneous Intracerebral Hemorrhage
    5 Topics
    |
    1 Quiz
  25. Neuromonitoring Techniques
    5 Topics
    |
    1 Quiz
  26. Gastroenterology
    Acute Upper Gastrointestinal Bleeding
    5 Topics
    |
    1 Quiz
  27. Acute Lower Gastrointestinal Bleeding
    5 Topics
    |
    1 Quiz
  28. Acute Pancreatitis
    5 Topics
    |
    1 Quiz
  29. Enterocutaneous and Enteroatmospheric Fistulas
    5 Topics
    |
    1 Quiz
  30. Ileus and Acute Intestinal Pseudo-obstruction
    5 Topics
    |
    1 Quiz
  31. Abdominal Compartment Syndrome
    5 Topics
    |
    1 Quiz
  32. Hepatology
    Acute Liver Failure
    5 Topics
    |
    1 Quiz
  33. Portal Hypertension & Variceal Hemorrhage
    5 Topics
    |
    1 Quiz
  34. Hepatic Encephalopathy
    5 Topics
    |
    1 Quiz
  35. Ascites & Spontaneous Bacterial Peritonitis
    5 Topics
    |
    1 Quiz
  36. Hepatorenal Syndrome
    5 Topics
    |
    1 Quiz
  37. Drug-Induced Liver Injury
    5 Topics
    |
    1 Quiz
  38. Dermatology
    Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis
    5 Topics
    |
    1 Quiz
  39. Erythema multiforme
    5 Topics
    |
    1 Quiz
  40. Drug Reaction (or Rash) with Eosinophilia and Systemic Symptoms (DRESS)
    5 Topics
    |
    1 Quiz
  41. Immunology
    Transplant Immunology & Acute Rejection
    5 Topics
    |
    1 Quiz
  42. Solid Organ & Hematopoietic Transplant Pharmacotherapy
    5 Topics
    |
    1 Quiz
  43. Graft-Versus-Host Disease (GVHD)
    5 Topics
    |
    1 Quiz
  44. Hypersensitivity Reactions & Desensitization
    5 Topics
    |
    1 Quiz
  45. Biologic Immunotherapies & Cytokine Release Syndrome
    5 Topics
    |
    1 Quiz
  46. Endocrinology
    Relative Adrenal Insufficiency and Stress-Dose Steroid Therapy
    5 Topics
    |
    1 Quiz
  47. Hyperglycemic Crisis (DKA & HHS)
    5 Topics
    |
    1 Quiz
  48. Glycemic Control in the ICU
    5 Topics
    |
    1 Quiz
  49. Thyroid Emergencies: Thyroid Storm & Myxedema Coma
    5 Topics
    |
    1 Quiz
  50. Hematology
    Acute Venous Thromboembolism
    5 Topics
    |
    1 Quiz
  51. Drug-Induced Thrombocytopenia
    5 Topics
    |
    1 Quiz
  52. Anemia of Critical Illness
    5 Topics
    |
    1 Quiz
  53. Drug-Induced Hematologic Disorders
    5 Topics
    |
    1 Quiz
  54. Sickle Cell Crisis in the ICU
    5 Topics
    |
    1 Quiz
  55. Methemoglobinemia & Dyshemoglobinemias
    5 Topics
    |
    1 Quiz
  56. Toxicology
    Toxidrome Recognition and Initial Management
    5 Topics
    |
    1 Quiz
  57. Management of Acute Overdoses – Non-Cardiovascular Agents
    5 Topics
    |
    1 Quiz
  58. Management of Acute Overdoses – Cardiovascular Agents
    5 Topics
    |
    1 Quiz
  59. Toxic Alcohols and Small-Molecule Poisons
    5 Topics
    |
    1 Quiz
  60. Antidotes and Gastrointestinal Decontamination
    5 Topics
    |
    1 Quiz
  61. Extracorporeal Removal Techniques
    5 Topics
    |
    1 Quiz
  62. Withdrawal Syndromes in the ICU
    5 Topics
    |
    1 Quiz
  63. Infectious Diseases
    Sepsis and Septic Shock
    5 Topics
    |
    1 Quiz
  64. Pneumonia (CAP, HAP, VAP)
    5 Topics
    |
    1 Quiz
  65. Endocarditis
    5 Topics
    |
    1 Quiz
  66. CNS Infections
    5 Topics
    |
    1 Quiz
  67. Complicated Intra-abdominal Infections
    5 Topics
    |
    1 Quiz
  68. Antibiotic Stewardship & PK/PD
    5 Topics
    |
    1 Quiz
  69. Clostridioides difficile Infection
    5 Topics
    |
    1 Quiz
  70. Febrile Neutropenia & Immunocompromised Hosts
    5 Topics
    |
    1 Quiz
  71. Skin & Soft-Tissue Infections / Acute Osteomyelitis
    5 Topics
    |
    1 Quiz
  72. Urinary Tract and Catheter-related Infections
    5 Topics
    |
    1 Quiz
  73. Pandemic & Emerging Viral Infections
    5 Topics
    |
    1 Quiz
  74. Supportive Care (Pain, Agitation, Delirium, Immobility, Sleep)
    Pain Assessment and Analgesic Management
    5 Topics
    |
    1 Quiz
  75. Sedation and Agitation Management
    5 Topics
    |
    1 Quiz
  76. Delirium Prevention and Treatment
    5 Topics
    |
    1 Quiz
  77. Sleep Disturbance Management
    5 Topics
    |
    1 Quiz
  78. Immobility and Early Mobilization
    5 Topics
    |
    1 Quiz
  79. Oncologic Emergencies
    5 Topics
    |
    1 Quiz
  80. End-of-Life Care & Palliative Care
    Goals of Care & Advance Care Planning
    5 Topics
    |
    1 Quiz
  81. Pain Management & Opioid Therapy
    5 Topics
    |
    1 Quiz
  82. Dyspnea & Respiratory Symptom Management
    5 Topics
    |
    1 Quiz
  83. Sedation & Palliative Sedation
    5 Topics
    |
    1 Quiz
  84. Delirium Agitation & Anxiety
    5 Topics
    |
    1 Quiz
  85. Nausea, Vomiting & Gastrointestinal Symptoms
    5 Topics
    |
    1 Quiz
  86. Management of Secretions (Death Rattle)
    5 Topics
    |
    1 Quiz
  87. Fluids, Electrolytes, and Nutrition Management
    Intravenous Fluid Therapy and Resuscitation
    5 Topics
    |
    1 Quiz
  88. Acid–Base Disorders
    5 Topics
    |
    1 Quiz
  89. Sodium Homeostasis and Dysnatremias
    5 Topics
    |
    1 Quiz
  90. Potassium Disorders
    5 Topics
    |
    1 Quiz
  91. Calcium and Magnesium Abnormalities
    5 Topics
    |
    1 Quiz
  92. Phosphate and Trace Electrolyte Management
    5 Topics
    |
    1 Quiz
  93. Enteral Nutrition Support
    5 Topics
    |
    1 Quiz
  94. Parenteral Nutrition Support
    5 Topics
    |
    1 Quiz
  95. Refeeding Syndrome and Specialized Nutrition
    5 Topics
    |
    1 Quiz
  96. Trauma and Burns
    Initial Resuscitation and Fluid Management in Trauma
    5 Topics
    |
    1 Quiz
  97. Hemorrhagic Shock, Massive Transfusion, and Trauma‐Induced Coagulopathy
    5 Topics
    |
    1 Quiz
  98. Burns Pharmacotherapy
    5 Topics
    |
    1 Quiz
  99. Burn Wound Care
    5 Topics
    |
    1 Quiz
  100. Open Fracture Antibiotics
    5 Topics
    |
    1 Quiz

Participants 432

  • Allison Clemens
  • April
  • ababaabhay
  • achoi2392
  • adhoward1
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Lesson 98, Topic 1
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Foundational Principles of Burn Shock Pathophysiology and Hypermetabolism

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Foundational Principles of Burn Shock Pathophysiology and Hypermetabolism

Foundational Principles of Burn Shock Pathophysiology and Hypermetabolism

Objectives Icon A checkmark inside a circle, symbolizing achieved goals.

Learning Objective

Understand global and patient-specific factors driving burn shock and hypermetabolism to guide fluid and metabolic support in major burns.

1. Epidemiology of Severe Burn Injuries

Burn injuries represent a significant global health burden, affecting millions of individuals annually. Mortality and morbidity are disproportionately concentrated in low- and middle-income countries (LMICs), where access to specialized care is limited. The incidence and outcomes of burn injuries are heavily influenced by a complex interplay of factors including the mechanism of injury, age, occupation, and underlying socioeconomic conditions.

  • Global Burden: Approximately 9 million new burn injuries occur each year, leading to an estimated 180,000 deaths, with the vast majority in LMICs.
  • Regional Trends: While high-income countries have seen a modest decline in burn incidence, LMICs face a rising number of absolute admissions due to population growth and industrialization.
  • Demographics: Peak incidence occurs in males aged 10–19 years, often due to occupational hazards, and in adults aged 40–60 years, commonly from domestic flame or scald injuries.
  • Etiology: The most frequent mechanisms are thermal (flame, scalds), followed by electrical and chemical exposures.
  • Socioeconomic Risks: Factors such as household overcrowding, inadequate safety equipment in workplaces, and delayed transport to care facilities are major contributors to both incidence and severity.
Key Points IconA lightbulb icon. Key Strategic Points
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Prevention Programs: Public health initiatives should be targeted at high-risk environments. Examples include promoting stove safety in domestic settings and enforcing workplace regulations for handling flammable materials or electricity.

System Planning: Mapping burn incidence data is crucial for optimizing the strategic placement of prehospital resources, specialized burn centers, and overall trauma system planning to reduce delays in care.

2. Pathophysiology of Burn Shock

A severe burn, typically defined as involving over 20% of the Total Body Surface Area (TBSA), initiates a profound systemic inflammatory response syndrome (SIRS). This cascade leads to widespread endothelial injury and a dramatic increase in capillary permeability, causing a massive shift of plasma, electrolytes, and proteins from the intravascular space into the surrounding interstitium. This process, known as “third-spacing,” results in profound intravascular volume depletion and tissue hypoperfusion, defining the state of burn shock.

Pathophysiology of Burn Shock Flowchart A flowchart showing the progression from a major burn injury to systemic inflammation, capillary leak, intravascular volume loss, and ultimately burn shock. Major Burn Injury (>20% TBSA) Systemic Inflammatory Cascade Endothelial Injury & Capillary Leak (TNF-α, ILs) Intravascular Volume Loss Burn Shock
Figure 1: The Cascade to Burn Shock. A major burn triggers a systemic release of inflammatory mediators, leading to glycocalyx degradation and capillary leak. The resulting shift of fluid into the interstitium causes severe intravascular depletion and hypoperfusion.
  • Hemodynamic Phases: The initial 24 hours are characterized by a hypodynamic state (“ebb phase”) with low cardiac output and high systemic vascular resistance, partly due to myocardial depressant factors. This is followed by a prolonged hyperdynamic state (“flow phase”) after 24-48 hours, driven by catecholamines, featuring a high cardiac index and low afterload.
Clinical Pearls IconA shield with a checkmark. Clinical Pearls: Resuscitation Targets
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  • Early Resuscitation: Initiate balanced crystalloid resuscitation (e.g., Lactated Ringer’s) within the first hour of injury. Early fluid administration is critical to support preload and may help protect the endothelial glycocalyx from further degradation.
  • Urine Output Goals: Titrate fluid rates to maintain a target urine output of 0.5 mL/kg/hr in adults and 1.0 mL/kg/hr in children under 30 kg. This is the primary indicator of adequate end-organ perfusion.
  • Invasive Monitoring: In patients with massive burns, pre-existing comorbidities (especially cardiac), or signs of “fluid creep” (resuscitation volumes >6-7 mL/kg/%TBSA), the use of an arterial line for continuous blood pressure monitoring and advanced hemodynamic devices (e.g., assessing stroke volume variation) is recommended.

3. Hypermetabolic Response Post-Burn

Following the initial shock phase, burn patients enter a prolonged state of extreme hypermetabolism and hypercatabolism. This response, driven by a massive and sustained surge of stress hormones like catecholamines, cortisol, and glucagon, can double or even triple the patient’s resting energy expenditure (REE). This intense metabolic state leads to profound muscle and fat breakdown, which, if unmanaged, severely impairs wound healing, immune function, and survival.

  • Hormonal Drivers: Epinephrine, norepinephrine, cortisol, and glucagon work synergistically to increase heart rate, stimulate hepatic gluconeogenesis, and drive systemic protein and fat breakdown.
  • Metabolic Consequences:
    • Proteolysis: Skeletal muscle is broken down to supply amino acids for gluconeogenesis and the synthesis of acute phase proteins.
    • Lipolysis: Stored fats are mobilized into free fatty acids for energy, but this process is often inefficient and insufficient to meet the extreme energy demands.
  • Duration: The REE typically peaks 7–10 days after the injury and can remain significantly elevated for up to two years, contributing to long-term muscle wasting and weakness.
Monitoring the Hypermetabolic Response
Parameter Goal / Target Clinical Significance
Indirect Calorimetry Feed to 120–150% of measured REE Gold standard for determining precise caloric needs, preventing both under- and overfeeding.
Nitrogen Balance Protein goal: 1.5–2.0 g/kg/day Calculated from a 24-hour urine urea nitrogen collection; guides protein provision to minimize catabolism.
Blood Glucose 140–180 mg/dL Tracks stress-induced hyperglycemia and insulin resistance; tight control improves outcomes.
C-Reactive Protein (CRP) Trending down A general marker of the inflammatory state; a downward trend suggests the hypermetabolic response is waning.
Key Intervention IconA pill capsule icon. Key Intervention: Beta-Blockade
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One of the most effective strategies to blunt the hypermetabolic response is the use of non-selective beta-blockade with propranolol.

  • Dosing: Typically initiated at 0.5 mg/kg/day, divided every 6 hours, and titrated to achieve a 15-20% reduction in resting heart rate.
  • Benefits: Propranolol directly counteracts the effects of catecholamines, leading to decreased peripheral lipolysis, improved protein balance, and reduced cardiac work.
  • Monitoring: Requires close monitoring for hypotension and bronchospasm, especially during initial titration.

4. Impact of Chronic Diseases on Resuscitation Needs

Pre-existing comorbidities significantly alter a patient’s physiological response to a major burn, complicating fluid resuscitation, metabolic support, and wound healing. Management must be individualized to account for these underlying conditions.

Diabetes Mellitus

Patients with diabetes exhibit impaired microvascular function and leukocyte activity, which can lead to deeper burn progression and a heightened risk of infection. Stress hyperglycemia is often severe and requires an insulin infusion targeting a blood glucose range of 140–180 mg/dL to mitigate its detrimental effects and support anabolism.

Cardiovascular Disease

Reduced cardiac ejection fraction or diastolic dysfunction markedly increases the risk of fluid overload and pulmonary edema during resuscitation. A goal-directed fluid strategy using dynamic parameters like stroke volume variation is essential. In cases where fluid limits are reached before perfusion is adequate, the early addition of a low-dose vasopressor (e.g., norepinephrine 0.01–0.05 µg/kg/min) is indicated.

Renal Insufficiency

Patients with baseline chronic kidney disease have a lower tolerance for large fluid volumes. Resuscitation must be carefully managed to avoid excessive water accumulation, and all nephrotoxic medications should be minimized. Continuous renal replacement therapy (CRRT) is reserved for established acute kidney injury (AKI) and has not shown benefit when used prophylactically.

Obesity

In patients with obesity, TBSA estimations should be performed using standardized charts (e.g., Lund-Browder) to avoid errors. Nutritional calculations should be based on an adjusted or ideal body weight to prevent overfeeding.

5. Influence of Social Determinants of Health (SDOH)

Recovery from a major burn extends far beyond the hospital walls. Social and economic factors, often referred to as Social Determinants of Health (SDOH), play a critical role in a patient’s ability to adhere to complex care regimens and achieve optimal long-term functional outcomes.

  • Access to Care: Geographic isolation and gaps in emergency medical services can delay transfer to a specialized burn center, leading to deeper burn wounds and more severe shock.
  • Nutritional Status: Pre-existing malnutrition is a strong predictor of poor wound healing and infectious complications. Early involvement of a registered dietitian is crucial.
  • Health Literacy & Psychosocial Factors: A limited understanding of fluid and nutrition goals can reduce compliance with outpatient regimens. Furthermore, cultural beliefs or economic hardship may hinder the consistent use of essential therapies like pressure garments or physical therapy.
Key Pearl IconTwo people figures representing social support. Key Pearl: Multidisciplinary SDOH Intervention
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A proactive, structured approach to addressing SDOH can significantly improve long-term outcomes. This involves:

  • Systematic Screening: Using standardized screening tools upon admission to identify risks such as food insecurity, lack of transportation, or inadequate social support.
  • Team Coordination: Engaging social workers, case managers, and community health resources early in the hospital course to develop a safe and achievable discharge plan that addresses identified barriers.

References

  1. Zhou M, Wang H, Zeng X, et al. The epidemiological characteristic and trends of burns globally. BMC Public Health. 2022;22(1):1593.
  2. Cartotto R, Johnson LS, Savetamal A, et al. American Burn Association Clinical Practice Guidelines on Burn Shock Resuscitation. J Burn Care Res. 2023;45(3):565–589.
  3. Nguyen TT, Gilpin DA, Meyer NA, Herndon DN. Current Treatment of Severely Burned Patients. Ann Surg. 1996;223(1):14–25.
  4. Saffle JR. The phenomenon of ‘fluid creep’ in acute burn resuscitation. J Burn Care Res. 2007;28(3):382–395.
  5. Jeschke MG, van Baar ME, Choudhry MA, et al. Burn injury. Lancet. 2020;396(10252):586–596.
  6. Stark R, et al. Pediatric Burn Hypermetabolic Protocol. Vanderbilt University Medical Center. 2022.
  7. Hultman CS, Palmieri TL. What fuels the fire: social determinants in burn injuries and outcomes. Burns Trauma. 2022;10:tkac022.
  8. Palmu R, Vuola J, Isometsä E, et al. Factors influencing outcomes after burn injuries: a prospective cohort study. BMJ Open. 2017;7(6):e017545.
  9. Miller AC, et al. Social determinants screening in an outpatient burn setting. J Burn Care Res. 2025;46(Suppl 1):S332.