RECOGNITION & TREATMENT OF SHOCK IN ANIMALS EMERGENCY PROCEDURES

SHOCK: RECOGNITION AND TREATMENT SHOCK is inadequate tissue perfusion resulting in poor oxygen delivery Cardiogenic Distributive Obstructive Hypovolemic

Shock TYPES OF SHOCK: – Cardiogenic: results from heart failure ↓ blood pumped by heart HCM, DCM, valvular insufficiency/stenosis – Distributive: blood flow maldistribution (Vasodilation) Sepsis, anaphylaxis →↓ arteriole resistance → loss of fluid from vessels to interstitial spaces →↓ BP → ↓ blood return to heart

SHOCK: RECOGNITION & TREATMENT TYPES OF SHOCK: – Obstructive - physical obstruction in circulatory system HW disease → heart pumping against the adult worm blockage Gastric torsion →↓ blood return to heart – Hypovolemic - decreased intravascular volume Most common in small animals Blood loss, dehydration from excessive vomiting/diarrhea, effusion of fluid into 3 rd spaces

HYPOVOLEMIC SHOCK  Pathophysiology of hypovolemic shock: ↓ blood vol →↓ venous return, ↓ vent filling →↓ stroke vol, ↓ CO →↓ BP

HYPOVOLEMIC SHOCK  Stage I: Compensation ◦ Baroreceptors detect hypotension ( ↓ BP) a. Sympathetic reflex—(Epi, Norepi, cortisol released from adrenals) - ↑ HR, contractility - Constriction of arterioles ( ↑ BP) to skin (cold, clammy), muscles, kidneys, GI tract; not brain, heart b. Renin (kidney) → angiotensin (blood) → aldosterone (adrenals) reflex - ↑ Na + and water retention → ↑ intravascular vol ( ↑ BP) ◦ PE findings  Tachycardia  Prolonged cap refill time  Pale mm

HYPOVOLEMIC SHOCK Pathophysiology of hypovolemic shock Stage II: Decompensation – Tachycardia – Delayed cap refill time – Muddy mm (loss of pink color, more brown than pink) – BP IS DROPPING – Altered mental state Stage III: Irreversible shock – PE findings worsen – cannot revive – death will occur

HYPOVOLEMIC SHOCK Treatment: the goal of therapy is to improve O 2 delivery O 2 supplementation Face mask O 2 cage/hoods Transtracheal/nasal insufflation Venous access Cephalic Saphenous Jugular Intraosseous

Oxygen supplementation

FLUID ADMINISTRATION CEPHALIC CATHETER PLACEMENT INTRAOSSEOUS CATHETER PLACEMENT

CONTRAINDICATED IN PATIENTS WITH SEPSIS,FRACTURES, OR INFECTED BONES INTRAOSSEOUS CATHETER PLACEMENT

SHOCK Treatment – Fluid resuscitation (O 2 delivery is improved by ↑ CO) 1. Crystalloids Isotonic solutions (electrolytes: Na +, Cl -, K +, bicarbonate) – Examples (body fluid= mOsm/L) » Lactated Ringer’s (273 mOsm/L) » Normal saline (0.9%) (308 mOsm/L) – Dose: Dog ml/kg/hr Cat ml/kg/hr

SHOCK Treatment: 1. Crystalloids continued Hypertonic solutions— when lg vol of fluid cannot be administered rapidly enough – Examples—7.5% saline – Causes fluid shift from intercellular space → intravascular space →↑ vascular vol →↑ venous return → ↑ CO – Also causes vasodilation → ↑ tissue perfusion – Dose: 4-6 ml/kg over 5 min Hypotonic solutions should never be used for hypovolemic shock – Examples—5% Dex in water (252 mOsm/L)

SHOCK Treatment Fluid resuscitation (O 2 delivery is improved by ↑ CO) 2. Colloids— Large molecular wt solutions that do not leave vascular system Better blood volume expanders than crystalloids 50-80% of infused volume stays in blood vessels Examples Whole blood Plasma Dextran 70, Hetastarch, Vetstarch

SHOCK Treatment (continued) – Sympathomimetics Use only after adequate fluid administration if BP and tissue perfusion have not returned to normal Dopamine (Inotropin®) – μ g/kg/min » Dilation of renal, mesenteric, coronary vessels – μ g/kg/min »↑ contractility of heart »↑ HR – >7.5 μ g/kg/min » Vasoconstriction Dobutamine (Dobutrex®) – ↑ contractility of heart (min effect on HR)

SHOCK Monitoring Hemodynamic/metabolic sequelae of shock are continually changing – Physical Parameters Respiratory – Color of mm – RR – Breathing efforts smooth? – Breathing pattern regular? – Auscultation normal? Cardiovascular – HR normal? – ECG normal? – Color of mm – Cap refill time (1-2 sec) – Urine production? (1-2 ml/kg/hr) – Weak pulse? → ↓ stroke volume

SHOCK Monitoring Physiologic Monitoring Parameters O 2 Saturation Pulse oximetry—noninvasive Normal: Hb saturations (SpO 2 )>95% oSpO 2 <90%--serious hypoxemia Arterial BP—a product of CO, vascular capacity, blood volume

SHOCK Monitoring – Laboratory Parameters Hematocrit (PCV) – Increase → dehydration – Decrease → blood loss Electrolytes – Proper balance needed for proper cell function – Fluid therapy may alter the balance; supplement fluid as needed

SHOCK Monitoring Arterial pH and blood gases – Pa CO2 tells how well patient is ventilating » Pa CO2 <35 mm Hg → hyperventilation » Pa CO2 >45 mm Hg → hypoventilation – Pa O2 Tells how well patient is being oxygenated » Pa O2 <90 mm Hg → hypoxemia – pH tells acid/base status of patient – <7.35 → acidosis – >7.45 → alkalosis