Resuscitation and Shock

Flashcards on resuscitation and shock covering definitions, stages, classifications, diagnostic criteria, and management principles.

Shock

The inability of the body to meet cellular requirements for oxygen, characterized by three stages (compensated, decompensated, refractory) and four classifications.

Compensatory Stage of Shock

The initial stage of shock where oxygen delivery to tissues starts to fall and microcirculation to tissue beds is restricted, causing mitochondria to switch to anaerobic metabolism and produce lactic acid.

Serum Lactate

A laboratory-tested metabolite produced during anaerobic metabolism that serves as a useful early marker of shock.

Renal Compensatory Mechanism in Shock

A hormonal pathway triggered by decreased renal blood flow where renin is secreted from the JGA, converting to Angiotensin I, Angiotensin II, and Aldosterone, while the posterior pituitary secretes ADH to retain water and sodium.

Metabolic Compensatory Mechanism in Shock

A hormonal pathway where the hypothalamus stimulates ACTH secretion to release cortisol from the adrenal cortex (increasing blood glucose by reducing glucose-to-lipid conversion) and the adrenal medulla secretes epinephrine and norepinephrine.

Chemical Compensatory Mechanism in Shock

A response triggered by decreased $O_2$, decreased pH, and increased $PaCO_2$ stimulating chemoreceptors, leading to hyperventilation, respiratory alkalosis, cerebral vasoconstriction, cerebral ischemia, and reduced level of consciousness over time.

Decompensated Stage of Shock

Also known as progressive shock; characterized by increased capillary permeability, third spacing, decreased preload, hypotension, microemboli formation, Disseminated Intravascular Coagulation (DIC), sodium-potassium pump failure, and Systemic Inflammatory Response Syndrome (SIRS).

Refractory Stage of Shock

The terminal stage of shock where compensatory mechanisms have failed, permanent organ dysfunction is occurring, mortality is $60XX$ or more, and high-dose vasopressors are required.

Multiple Organ Dysfunction Syndrome (MODS)

A severe medical state defined as the dysfunction or failure of $2$ or more organ systems, classified as primary (direct insult like trauma) or secondary (slower failure from progressive shock cascade).

Cardiogenic Shock

A state of heart failure defined by sustained systolic blood pressure $< 90\,\text{mmHg}$ for greater than $30\,\text{minutes}$, cardiac index $< 2.2$, pulmonary capillary wedge pressure (PCWP) $> 15\,\text{mmHg}$, and evidence of end-organ damage.

Hypovolemic Shock

The most common classification of shock encountered in medical care, resulting from significant intravascular fluid loss or acute blood loss.

Class IV Hemorrhagic Shock

Severe hypovolemic shock involving greater than $40\%$ blood loss, base deficit of $-10\,\text{mEq/L}$ or less, marked hypotension, and requiring the Massive Transfusion Protocol.

Massive Transfusion Protocol (MTP)

A blood product administration protocol used in severe hemorrhage involving more than $10\,\text{units}$ of red blood cells in $24\,\text{hours}$, delivered in a $1:1:1$ ratio of packed red blood cells (PRBCs), fresh frozen plasma (FFP), and platelets (PLT).

Distributive Shock

A classification of shock caused by a widespread loss of vascular tone, which includes neurogenic, anaphylactic, septic, and specific endocrine subtypes.

Neurogenic Shock

A subtype of distributive shock caused by a loss of sympathetic tone (due to trauma, drugs, or anticholinergic toxicity), resulting in profound peripheral vasodilation, bradycardia, and altered thermoregulation.

Anaphylactic Shock

A subtype of distributive shock characterized by systemic vasodilation, increased capillary permeability, relative hypovolemia, and smooth muscle constriction (bronchoconstriction) caused by histamine release.

Septic Shock

A subtype of distributive shock defined as persistent hypotension in the presence of sepsis that is unresponsive to fluid resuscitation.

Obstructive Shock

A classification of shock caused by a physical obstruction to the great vessels or heart that reduces preload, such as cardiac tamponade, pulmonary thromboembolism, or tension pneumothorax.

Lethal Triad

A life-threatening clinical combination of coagulopathy, hypothermia, and acidosis that mutually exacerbate each other during severe shock and trauma.

Post-Resuscitation Management

Care principles following initial shock resuscitation that include serial $12$-lead ECG monitoring, crystalloid boluses and pressors to maintain mean arterial pressure (MAP) $> 65\,\text{mmHg}$, and targeted temperature management.