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Ch. 5: Surgical Shock, Screen Shot 2024-12-15 at 11.19.27 PM,…
Ch. 5: Surgical Shock
Distributive
• Early: ↔ preload
• Late: ↓ preload
• Both: ↑ or ↓ CO, ↓ SVR, > 65% SVO2
↑↑ vasodilation of peripheral vasculature → impaired distribution of blood flow
Septic
• most common
• original definition → infection source & 2+ SIRS criteria:
- temp above 101.3 or below 96.8
- HR > 90/bpm
- RR > 20 bpm or PaO2 < 32 mmHg
- WBC > 12,000 or < 4,000
• Better assessment now is the SOFA score (Sequential Organ Failure Assessment); score of 0 good, for score 2+ with infection mortality is 10%
• qSOFA good for bedside → RR ≥ 22 bpm, altered mental status, SBP ≤ 100 mmHg
• state of persistent hypotension (MAP ≤ 65 mmHg despite adequate fluid resuscitation
• vasopressors may be required to achieve and maintain a MAP ≥ 65 mm Hg
• will have serum lactate > 2 (anaerobic metabolism)
Physicial exam
• febrile or hypothermic
• tachycardia and tachypnea
• warm and clammy → continued hypoperfusion and microcirculatory dysfunction → skin mottling and cold skin
• decreases in mentation, urine output, and GI motility (the latter causing ileus)
Treatment
- Source control!!!! (often surgical)
- Resuscitation and life support (if patient is critically ill)
- start broad antibiotics in 1st hour (mortality ↑ by 10% per hr of antibiotic delay)
- obtain cultures before starting antibiotic if possible (to identify infectious source), but do NOT delay giving antibiotics to get cultures
- Fluids (see side note)
- Vasopressor medications are often needed to support MAP (see side note)
- If septic shock proves resistant to fluids and vasopressors →
try hydrocortisone administration at 50 mg IV every 6 hours (Patients in septic shock can often develop adrenal insufficiency, and the addition of hydrocortisone may allow these patients to be weaned from vasopressor support.)
- Mechanical ventilation
- Renal replacement therapy if severe AKI
Fluids
• 30mL/kg crystalloid infusion in the first 3 hrs of the identification of sepsis to support BP
• Urine output greater than 0.5 mL/kg in the nonoliguric patient is a helpful determination of adequate volume status
• bedside US can assess either collapsibility of the IVC or jugular vein to assess fluid status
Vasopressors
• 1st line: Norepinephrine (vasoconstrictive + inotropic → ↑ vascular tone, ↑ HR)
• 2nd line: Epinephrine (same as norepi)
• 3rd line: Dopamine (vasoconstrictive but also chronotropic → can cause significant tachyarrhythmias
• Can add Vasopressin adjunctively (potent vasoconstrictor; dose should never exceed 0.04 units/minute due to ischemia risk)
• DO NOT USE Phenylephrine in septic shock; although it is a potent α-agonist for aggressive vasoconstriction, it significantly ↑ the patient’s afterload, causing the heart to work harder in an already significantly stressed state.
Anaphylactic
• severe allergic reaction, especially affects cardio and resp
• Immunoglobulin E binds the source antigen → mast cells and basophils have massive release of inflammatory mediators such as histamine → smooth muscle contraction within the bronchi, severe vasodilatation, leaking capillaries, and depressed heart contractility
Neurogenic
• most commonly a result of traumatic injury to the spinal cord at the level of T6 and higher → complete dysregulation of the sympathetic nervous system → inappropriate vasodilation → resultant hypotension, bradyarrhythmias, and temperature dysregulation
Treatment
- get basic labs
- get CT or MRI
- assess fluid status: Infusion of 1-2 L of isotonic crystalloid
- MAP goals > 85 mmHg; add a vasopressor if not obtained with fluid resuscitation
• 1st line hypotension WITHOUT bradycardia: Phenylephrine (α-adrenergic receptor agonist; isolated vasoconstriction of the peripheral vasculature)
• 1st line hypotension WITH bradycardia: Norepinephrine; sympathomimetic that increases HR and CO
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Hypovolemic
• Early: ↔ preload, ↔ CO, > 65% SVO2
• Late: ↓ preload, ↓ CO, < 65% SVO2
• Both: ↑ SVR
↓ intravascular volume → ↓ preload → ↓ CO
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Obstructive
PE
• Early: ↔ preload, ↔ CO
• Late: ↓ preload, ↓ CO
• Both: ↑ SVR, > 65% SVO2
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