Shock

Shock (usually hypotensive)

  • ↓ O2 delivery (↓ perfusion) or ↑ O2 consumption or ↓ oxygen utilization ➔ tissue/cellular hypoxia

    • Without O2 for electron transport chain ➔ ↓ ATP

      • Switch to anaerobic respiration (less effective ATP production) ➔ lactic acid production (Lactate level correlates with severity of shock)

    • Without intervention ➔ systemic progression

      • Metabolic acidosis & endothelial dysfunction (stays constricted) with shunting of regional blood flow ➔ further tissue injury

      • Eventually resulting in irreversible organ failure

Shock index = HR/systolic BP (Normal 0.4 - 0.7)

  • Higher is bad: a pt with systolic BP of 90 and HR of 120...

    • 120/90 = 1.3

  • Not for use in pediatric pts because KIDS COMPENSATE (look fine and then decline rapidly)

Body's response to shock

SSX

  • Compensated (cryptic/pre) shock

    • Activate sympathetic nervous and inhibit parasympathetic:

      • ↑ HR and vasoconstriction of peripheral vessels to ↑ systemic vascular resistance

        • May only see slight tachycardia and ↑ BP in young/healthy pts

    • RAAS activation ➔ ↑↑ vasoconstriction, urine retention, thirst

  • Shock

    • Body isn't able to keep up ➔ sx of organ dysfunction

      • Cool, clammy, hypotensive

      • Restless with hypotension & oliguria

  • End-organ dysfunction

    • Irreversible organ damage ➔ multiorgan failure (MOF) ➔ death

      • Acute renal failure ➔ anuria

      • Acidosis blunts nervous/RAAS system and likely causes a further ↓ CO

      • Irreversible shock/refractory hypotension

      • Obtundation, coma, death

Hemodynamic profiles - PAC

Pulmonary artery catheter (PAC/Swan-Ganz/right heart catheter)

  • Measures CO, pulmonary capillary wedge pressure (PCWP), systemic vascular resistance

    • PCWP: left atria end diastolic pressure (preload)

      • Hypovolemia, obstructive shock (PE) ➔ ↓ preload ➔ ↓ PCWP

      • ↑ end diastolic pressure (MI ➔ systolic failure, cardiac tamponade ) ➔ ↑ preload ➔ ↑ PCWP

  • PCWP aka pulmonary artery occlusion pressure, pulmonary artery wedge pressure

    • There are way more measurements in PAC than just CO, PCWP, and SVR

    • Like mixed venous oxygen saturation (SvO2): Oxygen saturation in pulmonary artery (the end result of O2 consumption/delievery)

      • Indicates how well O2 is being delivered to periphery

      • Usually < 65% in cardiogenic shock and pericardial tamponade (Normal SvO2 = 65 - 70%)

Hypovolemic

Leaking blood or non-blood fluids

Causes

  • Hemorrhagic

    • Trauma, intra/post-op bleeding

    • AAA

    • GI bleed - ruptured varices, PUD

    • Ruptured ectopic/postpartum uterine/hemorrhage

    • Bleeding disorders

  • Non-hemorrhagic

    • GI losses vomiting/diarrhea

    • Burns

    • Drug/osmotic diuresis, salt-wasting, hypoaldosterone

    • Third spacing: intestinal obstruction, pancreatitis

SSX

  • Shocky

  • cool/clammy or dry, thready pulse, hypotension, cap refill >2s

DX

  • CBC

    • Dehydration ➔ hemoconcentration ➔ ↑ hemoglobin/hematocrit

    • Blood loss ➔ ↓ h/h

TX

  • If there is a hole... plug it

  • Bilateral lage bore IVs (and locks) for IVF resuscitation (NS or LR)

  • O-negative or cross matched packed RBCs in severe bleeds

    • (NS doesn't carry oxygen)

Cardiogenic

Pumping issue ➔ backup ➔ ↑ preload

Causes

  • MI

  • Arrhythmias

  • HF/Cardiomyopathy

  • Myocarditis

  • AR/MR

  • β-blockers, CCB

SSX

  • Shocky, dyspnea (pulm edema), abnormal HS (S3/4, AR/MR)

  • Chest pain/palpitations/syncope

  • JVD

DX

  • EKG, cardiac markers, ECHO

TX

  • Tx underlying cause (PCI for MI)

  • Avoid aggressive IVF (don't add more work for heart)

  • O2 and inotropes to ↑ CO (dobutamine, EPI)

    • Amrinone or intra-aortic balloon pump when all else fails

Obstructive

Impaired RV diastolic filling

Causes

SSX

  • Shocky + JVD + ssx related to cause

  • Pulsus paradoxus

  • Beck triad (tamponade): Hypotension, Muffled HS, JVD

  • Tension pneumo: SQ emphysema ➔ crepitus, ↓ breath sounds, hyperresonance

  • PE: Chest pain, syncope, dyspnea, hemoptysis, ↓ O2 sat despite supplemental O2

DX

  • PE, CXR, CT-A, ECHO (but don't wait to decompress)

TX

  • Decompress heart (tamponade ➔ pericardiocentesis, tension pneumo ➔ needle/chest tube, PE ➔ thrombolysis)

Distributive

Fluid redistributed from intravascular to extravascular (sepsis)

Widespread vasodilation (anaphylaxis)

Septic shock (leakage issue)

  • Infxn ➔ deleterious response

  • Systemic vasodilation ➔ ↓ systemic vascular resistance

  • MCC pneumonia

SSX

  • Flushed/warm skin initially ➔ shocky

  • Wide pulse pressure, ↑ RR (from acidosis)

  • Typically fever

DX

  • SIRS with persistent hypotension

  • ↑ ESR, ↑ lactate, cultures, CBC: leukocytosis or leukopenia

TX

  • IVF and pressors (NE), broad spectrum ABX

Infection, trauma, inflammation ➔ SIRS

  • Systemic Inflammatory Response Syndrome

    • 2/4 required:

      • Temp > 38° C (100.4 F)

      • HR >90

      • RR >20

      • WBC < 4k or > 12k

  • Sepsis: (SIRS + suspected/confirmed infxn)

  • Severe sepsis: sepsis with organ failure

  • Septic shock: persistent hypotension

Anaphylaxis (vasodilation issue)

  • Type I hypersensitivity reaction

  • Systemic vasodilation ➔ flushed/warm skin and ↓ systemic vascular resistance

  • Rapid onset

SSX

  • Shocky, tachy

  • Wheezing/stridor, flushed/urticaria/pruritus

  • GI: N/V/D

DX

  • Clinical

TX

  • EPI & antihistamines ± glucocorticosteroid

  • IVF & O2 (airway)

Neurogenic

  • Lost sympathetic tone ↑ parasympathetic (vagal) tone

    • Peripheral vasodilation ➔ ↓ systemic vascular resistance

    • Spinal cord injury (MC above T6), TBI, head bleed

    • Neuraxial anesthesia (anesthetic in subarachnoidepidural space)

SSX

  • Brady

  • Wide pulse pressure

DX

  • CT to look for bleed

TX

  • Atropine/pacing for brady, IVF, pressors (EPI if HR < 60)