Shock

Anatomy and Physiology of Cardiovascular System CO = SV * HR (Normal = 4.0 - 8.0 l/min) MAP = Dist. Pressure + 1/3 Pulse Pressure (Normal = 70 - 105 mmHg) Preload (volume) After load (SVR) Contractility

Shock It is a state of generalized cellular hypoperfusion in which delivery of oxygen at the cellular level is inadequate to meet metabolic needs.

Signs and Symptoms of Shock Decreased LOC, anxiety, disorientation. Tachycardia, decreased SBP and pulse pressure Rapid shallow breathing Cold, pale, clammy, diaphoretic, cyanotic skin, decreased capillary refill time. Decreased urine output

Classification of Shock Hypovolemic shock (blood) Distributive shock (vasogenic) Cardiogenic (heart)

Severity of Shock Compensated shock: patient is developing shock but body still able to maintain perfusion. Decompensated shock: patient developed shock but body no longer can compensate. Irreversible shock: patient developed shock but body is unable to maintain perfusion to organs.

Hypovolemic Shock It is the most common cause of shock in trauma patients. Causes: External: bleeding (trauma), GI bleeding, ruptured aneurysms, hemorrhagic pancreatitis. vomiting or diarrhea, adrenal insufficiency, diabetes insipidus, dehydration Internal: third spacing: intestinal obstruction, pancreatitis, cirrhosis

Hypovolemic Shock Markers: UOP,CVP, BP, HR, Hct, CO Treatment: ABCs, IVF (crystalloid), Blood Transfusion. Patients on β-blockers, or with spinal shock & athletes may not be presented with tachycardia.

Categories of Hemorrhagic Shock Class I Class II Class III Class IV Blood Loss % < 750 ml < 15 % 750-1500 ml (15-30 %) 1500-2000 ml (30-40 %) > 2000 ml > 40 % HR (b/min) Normal or minimally ↑ > 100 > 120 > 140 Ventilatory R. (breath/min) Normal 20 – 30 30 – 40 > 35 SBP Decreased Greatly Decreased Urine Output (ml/hr) 5 – 15 Minimal

Distributive (Vasogenic) Shock It occurs when vascular container enlarges without a proportional increase in fluid volume. Septic Shock Neurogenic Shock Psychogenic (vasovagal) Shock

Septic Shock Caused by cytokines release in response to infection, sepsis: G(-/+ ) septicemia, e.g. pneumonia, peritonitis, etc. S & S: cool, clammy, pale, mottled skin, BP drop, altered LOC, slowed capillary refill. Markers: Temp, WBC count, … Rx: ABCs, IVF, Drainage (ie abscess).

Neurogenic Shock It occurs when injury interrupts the spinal cord sympathetic nervous system pathway. S & S: warm, dry, pink skin, bradycardia, BP drop, lucid LOC, normal capillary refill. Rx: IVF, vasoactive medications if refractory

Psychogenic Shock It is mediated through parasympathetic nervous system. (stimulation of vagal nerve) It is temporary state lasts for few minutes.

Cardiogenic Shock Failure of the heart’s pumping activity. Intrinsic Causes: Heart muscle damage Dysrhythmia Valvular disruption Extrinsic Causes: Cardiac tamponade Tension pneumothorax

Cardiogenic Shock S & S: cool, clammy, pale, cyanotic skin, BP drop, altered LOC, slowed capillary refill. Markers: CXR, CVP, CO. Rx: diuretics & vasodilators +/- pressures, decrease after load, intraaortic balloon pump

Complications of Shock Acute Renal Failure Acute Respiratory Distress Syndrome Hematologic Failure Hepatic Failure Multiple Organ Failure

Volume Resuscitation Enteral Route Vascular Access Intravenous route Intraosseous route

Intravenous Solutions Crystalloids Solutions Hypotonic solutions Isotonic solutions Hypertonic solutions Colloids Solutions Blood Substitutes

Colloids High molecular weight substances so do not cross capillary membranes. Used as volume or plasma expanders They include: Albumin Hetastarch Dextran

Blood It is given as packed RBCs, which should be cross-matched, but in an urgent situation, 1 to 2 units of type O Rh-negative blood are an acceptable alternative. When > 1 to 2 units are transfused (eg, in major trauma), blood is warmed to 37° C. Patients receiving > 8 to 10 units may require replacement of clotting factors with infusion of fresh frozen plasma or cryoprecipitate and platelet transfusion.