Deep Dive Questions Flashcards
What role does nitric oxide play in septic shock pathophysiology?
Inflammatory cytokines upregulate inducible nitric oxide synthase (iNOS), leading to excess nitric oxide → systemic vasodilation and decreased SVR.
How does lactic acidosis develop in septic shock?
Hypoperfusion and mitochondrial dysfunction cause cells to shift to anaerobic metabolism, producing lactate as a byproduct.
Why does ARDS cause decreased lung compliance?
Inflammatory damage leads to alveolar edema, surfactant inactivation, and hyaline membrane formation → stiff lungs.
How does systemic inflammation in sepsis affect the coagulation system?
Activation of coagulation cascade + suppression of fibrinolysis → microthrombi, DIC, and organ dysfunction.
What is the mechanism behind refractory hypoxemia in ARDS?
Intrapulmonary shunting — blood passes through non-aerated alveoli, bypassing gas exchange despite high FiO₂.
How does Preload, Afterload, and Contractility change in septic shock?
↓ Preload (vasodilation & capillary leak), ↓ Afterload (vasodilation), ↓ Contractility (myocardial depression from cytokines).
What receptor does ketamine act on, and how does it cause dissociative anesthesia?
NMDA receptor antagonist → disrupts thalamocortical pathways, leading to dissociation of sensory input from consciousness.
How does dexmedetomidine (Precedex) produce sedation and analgesia?
Alpha-2 receptor agonist in the CNS → ↓ norepinephrine release → sedation, anxiolysis, and mild analgesia.
What is the primary mechanism of action of benzodiazepines like midazolam (Versed)?
Binds GABA-A receptor → increases frequency of chloride channel opening → hyperpolarization → CNS depression.
Why does propofol cause hypotension?
Decreases systemic vascular resistance through vasodilation and directly depresses myocardial contractility.
What is the mechanism by which norepinephrine increases blood pressure?
Alpha-1 agonism → vasoconstriction ↑ SVR; beta-1 agonism → ↑ HR and contractility.
How does vasopressin work in vasodilatory shock?
Binds V1 receptors on vascular smooth muscle → vasoconstriction independent of adrenergic receptors.
Why might epinephrine cause hyperglycemia in septic patients?
Beta-2 receptor stimulation → glycogenolysis and gluconeogenesis; also inhibits insulin secretion.
What is the effect of prolonged high-dose fentanyl on the endocrine system?
Suppresses ACTH and cortisol → may contribute to adrenal insufficiency in critical illness.
