SHOCK

Nota:

• inadequate systemic + specific organ perfusion. it is recognised by features of tissue hypoperfusion, usually with hypotension BUT BP may be maintained until advanced stages (partic in young, fit and healthy) generally systolic BP <90

1. Hypovolemic
   1. pathophys
      1. decreased intravasc vol -> decreased cardiac filling pressures and decreased cardiac output -> compensatory increased HR and increased systemic vasc resist
   2. characteristic findings
      1. decreased JVP
      2. tachycardia
      3. decreased pulse vol 'thready'
      4. cool, clammy periphs
   3. causes
      1. Hemorrhage (any site)
         1. trauma, GI bleed, ruptured AAA, ectopic preg
      2. other fluid loss
         1. burns
         2. diarrhea, vomiting
         3. polyuria
         4. prolonged dehyd (partic elderly)
         5. third spacing (eg in condits such as bowel obstruct + acute pancreatitis)
2. Cardiogenic (pump failure)

   Nota:

   • 2ndry causes: PE, tension pneumothorax, cardiac tamponade
   1. pathophys
      1. cardiac disorders may -> valvular or myocard dysfunct
      2. extracardiac disorders may -> impede cardiac inflow or outflow (also known as 'obstructive shock')
   2. signs
      1. JVP up
      2. pulm edema (maybe)
      3. feats of underlying cause
      4. tachycardia
      5. decreased pulse vol 'thready'
      6. cool, clammy periphs
   3. tests
      1. echo often diagnostic
   4. cause
      1. MI

         Nota:

         • partic ant wall, large infarcts or from structural complics of MI eg papillary musc rupture, VSD, tamponade
         1. STEMI
            1. chest pain, ECG criteria
            2. py angioplasty (PCI) or thrombolysis
      2. L ventricular dysfunct w/o infarction
         1. incl tachy or brady arrhythmia
            1. tachy: VT or SVT >150bpm
               1. shock it!!! (DC cardioversion)
            2. brady: 3rd degree AV block or HR <40bpm
               1. atropine, adrenaline, external or transvenous pacing
         2. acute myocarditis
         3. end stage cardiomyopathy
      3. valve disorders
         1. prosthetic valve dysfunct
         2. endocarditis
         3. critical aortic stenosis
      4. tension pneumothorax
         1. typical findings
            1. resp distress
            2. tachycardia
            3. decreased ipsilateral air entry (check chest expansion)
            4. tracheal deviation OFTEN ABSENT
         2. immediate decompress essential

            Nota:

            • use venflon (grey or orange) in 2nd intercostal space mid clavic line
      5. cardiac tamponade

         Nota:

         • accum of fluid in pericardial space (pericardial effusion) impedes heart filling (&gt;200mL sufficient if accum rapid- eg trauma, aortic dissection)
         1. common signs

            Nota:

            • other signs:  muffled heart sounds kussmau's sign ( a pradoxical rise in JVP on insp) small complexes on ECG
            1. hypotension
            2. pulsus paradoxus

               Nota:

               • fall in BP more than 10mm Hg during quiet inspiration
            3. tachycardia
            4. increased JVP
            5. small QRS complexes on ECG
         2. echo will confirm presence of effusion, provide ev of cardiac compromise + guide therapeutic drainage
         3. treat
            1. pericardiocentesis
      6. massive PE
         1. presentation
            1. sudden onset chest pain
            2. dyspnea
            3. hypoxia with shock
               1. espec w/clear lung fields
         2. signs
            1. JVP up
            2. ECG may show feats of R heart strain
         3. CTPA if stable; urgen echo if unstable, nil if peri arrest
         4. treat
            1. thrombolysis
3. Distributive (vasodilation)
   1. pathophys
      1. periph vasodilat -> drop in systemic vasc resist and 'relative hypovolemia' (increased size of vasc space without corresponding increasein intravasc vol) -> compensatory rise in CO, insufficient to maintain BP
   2. causes
      1. Septic shock
         1. result of infect or other systemic inflamm resonse eg acute pancreatitis
         2. sepsis = SIRS + likely infection source
      2. Anaphylactic Shock
         1. very rapid onset bronchoconstriction, widepsread erythematous rash, severe distributive shcok
            1. resp distress, stridor, wheeze, angioedema, rash, precipitant
         2. preciptant (foodstuffs, drugs -partic abx- insect stings) may be ID'd
            1. TRANSFUSION REACTION is realted problem

               Nota:

               • ABO incompatitibility may present with shock as only initial sign partic in unconsc or sedated pts
         3. treat: epi pen (epinephrine), IV fluid
      3. drug causes
         1. antihypertensives + anesthetic agents (partic epidural + spinal anesthesia)
      4. adrenal crisis
         1. glucocorticoid defic may -> distrib shock, partic during acute stress eg infect, surg
      5. neurogenic
         1. rare, asssoc w/ direct inj to symp fibres that control vasc tone
   3. signs
      1. tachycardia
      2. hypotension
      3. warm periphs
      4. increased pulse volume
4. STAGES OF SHOCK
   1. 1. INITIAL- hypoperfusion -> hypoxia -> mitochondrial dysfunction -> anerobic metab -> METABOLIC ACIDOSIS
      1. 2. COMPENSATORY : hyperventilation -> resp alkalosis; catecholamine response in response to hypotension; Renin-angiotensin response -> vasoconstriction
         1. 3. PROGRESSIVE: mechs above begin to fail. cellular dysfunct, metabolic acidosis wosre, fluid loss into extravasc interstitial space
            1. 4. REFRACTORY: organs fail, shock non reversible. Death.