Types of Shock - Lecture Notes

Types of Shock Dr Umme Salma Department of Surgery  Objectives To Recognise and Understand: ▪ Definition ▪ Physiology and pathophysiology ▪ Types ▪ Causes ▪ Resuscitation ▪ Golden hours  Shock A serious medical condition ….. Circulatory system failure Body's organs...

Types of Shock Dr Umme Salma Department of Surgery  Objectives To Recognise and Understand: ▪ Definition ▪ Physiology and pathophysiology ▪ Types ▪ Causes ▪ Resuscitation ▪ Golden hours  Shock A serious medical condition ….. Circulatory system failure Body's organs and tissues don’t get enough oxygenated blood to function properly Affect working of organs… brain, heart, and kidneys,  organ damage or even failure. Could be a problem with the heart, blood vessels, or blood volume. Life threatening disorder of Circulatory Inadequate oxygen to meet system metabolic demand Reduction of systemic tissue perfusion Decreased tissue Global tissue hypo-perfusion and oxygen Metabolic acidosis delivery Stroke volume (SV): Volume of blood pumped out of heart during each systole (contraction) Normal value : 70 ml in a 70 kg man Cardiac Output (CO): Amount of blood your heart pumps each minute Cardiac output = stroke volume × heart rate. (SV x HR) Normal cardiac output is: 5 litres/min Pulse pressure: Difference of the Diastolic and Systolic pressure of cardiac cycle Normally 30-40mmHg Low/Narrow PP: due to dec Stroke volume High/ Wide PP: due to inc stroke volume Systemic / Peripheral vascular resistance: (SVR/PVR) The resistance in the circulatory system (in the vessels) that should be overcome to push blood and create blood flow Systemic vasoconstriction causes an Increased Vascular resistance Systemic vasodilatation causes a decreased Vascular resistance Measured by Pulmonary capillary wedge pressure... PCWP….. To some extent by CVP​ Influenced by SVR Measured by Systolic blood pressure General Homeostasis Pathophysiology Link: Pathophysiology of shock  Classification Of Shock Low Cardiac Output states Low peripheral resistance Heart isn’t pumping blood states effectively Blood vessels are too relaxed or dilated Body doesn’t get enough oxygen/nutrients Reduces the pressure in the arteries as there is no resistance to Key Points: flow Have Narrow Pulse Pressure Cold shock…. Key Points: Cold clammy skin Have Wide Pulse Pressure Warm shock…. Warm flushed skin  ….. Low Cardiac Output states Low peripheral resistance (Narrow Pulse Pressure /Cold states shock) (Widened Pulse Pressure/ Warm shock) Hypovolemic shock Bleeding / Dehydration Distributive shock Vasogenic Shock Cardiogenic shock  Septic Pump failure  Anaphylactic Neurogenic shock Obstructive Shock  Loss of sympathetic tone Pump obstruction …. Hypovolemic Shock: …. Hypovolemic Shock: Hemorrhagic shock Hemodynamic parameters: Due to hemorrhage Non-hemorrhagic shock Low Circulatory Volume Fluid loss (from GI tract, skin, kidneys, or third spacing) Decreased venous return and preload to heart (Low PCWP / CVP)​ ​ Decreased cardiac output​ Tachycardia ↑ Systemic vascular resistance ​ (Inc HR) (Inc SVR) …. … Cardiogenic Shock: A life-threatening condition where the heart is unable to pump enough blood to meet the body's needs, leading to insufficient oxygen and nutrients being delivered to organs and tissues. Pump Failure:​ Etiology:​ § Cardiac ischemia​ § Arrhythmias​ § Valvulopathy​ § Cardiotoxic substance exposure​ …. … Cardiogenic Shock: …. Obstructive Shock: Mechanical obstruction --> Prevents heart from filling properly or pumping enough blood Etiology ↓ Diastolic filling Cardiac tamponade, Constrictive pericarditis, Restrictive cardiomyopathy ↓ Venous return Tension pneumothorax, Intrathoracic tumor ↑ Ventricular afterload Massive PE, Aortic dissection, Aortic stenosis Large systemic emboli, Severe pulmonary hypertension …. Common mechanism: Obstruction of the heart or its great vessels Inability of the heart to circulate blood ↓ CO Compensatory ↑ SVR …. Distributive Shock: Includes septic shock, anaphylaxis and spinal cord injury Septic shock Infection (especially gram-negative bacteria) and bacteremia Anaphylactic shock Drug reactions, insect stings or bites, food allergies Neurogenic shock Spinal cord injury, traumatic brain injury, Cerebral hemorrhage Neuraxial anesthesia …. Common Mechanism: Vasodilation with or without capillary leakage …. Septic shock Usually after infections by bacteria...gram +vecocci Initial phase Release of bacterial products (endotoxin)...endotoxemia Activation of cellular and humoral components of the immune system. Later phases: complicated clinical picture Hypovolaemia from fluid loss into interstitial spaces Concomitant myocardial depression Neurogenic shock: Spinal cord injury  Damage of autonomic pathways Loss of sympathetic vascular tone → unopposed vagal tone Peripheral vasodilation Unopposed vagal effect Pooling of Peripheral blood Bradycardia ↓ HR Typical Hemodynamic parameters Estimat Estimated Estimated ed Cardiac Heart Rate Type preload afterloa output (HR) (PCWP) d (CO) (SVR) Hypovolemic ↓ ↓ ↑ ↑ Cardiogenic ↓↓ ↑ ↑ ↑ Obstructive ↓↓ ↓ Or ↑ ↑ ↑ Distributive: Neurogenic: ↓ ↓ Usually ↓ ↓↓ Septic & anaphylactic Early: ↑ ↑ Late: ↓ N.B. Red arrows denotes Primary Clinical Manifestation Type Manifestation Cold,clammy skin, slow capillary refill Hypovolemic Collapsed jugular veins (“empty heart”) shock Dec. skin turgor, dry mucous membranes Features of underlying etiology: GI bleed, diarrhea Cold,clammy skin, poor capillary refill Cardiogenic Elevated JVP, distended neck veins ( “full heart”) Shock Clinical features of heart failure Features of underlying etiology: o Chest pain, palpitations, syncope, new/worsening murmur Cold, clammy skin, poor capillary refill Obstructive Elevated JVP, distended neck veins Shock Features of underlying etiology: o Chest pain, dec breath sounds, tracheal deviation, muffled heart tones, clinical features of DVT  Type Manifestation Suspected or confirmed allergen exposure Anaphylact Rapid onset (minutes to hours) ic Clinical features of anaphylaxis Flushed, warm skin Neurogeni Bradycardia c Features of underlying etiology: neurological deficits (e.g., flaccid paralysis in spinal trauma) Early: Flushed, warm skin, normal capillary refill Septic Late: cold, pale skin with delayed capillary refill Features of sepsis: fever, SIRS criteria Shock Features of underlying infection: e.g., signs of typical pneumonia, meningismus …….Approach Microscopy to a Shocked Patient The following should be performed simultaneously: Perform ABCDE survey: Identify the need for immediate airway or breathing intervention Establish vascular access immediately: + blood for testing Preferred: ≥ 2 wide-bore IV cannulas Alternatives Intraosseus access (pediatrics age gp / adults) Central venous line CVL (for geriatric/old age gp….for monitoring purposes) Begin immediate hemodynamic monitoring Pulse, BP, RR, pulse oximetry, invasive cardiac monitoring as needed Microscopy Classify the type of shock Identify likely etiology of shock Investigations: Xrays, ECG, USG, serum lactate, ABGs Provide immediate hemodynamic support: Begin fluid resuscitation Determine the need for vasopressors, inotropes, or blood transfusion Always after fluids or resolving the need for fluid resuscitation Specific Management: Cardiogenic shock: Mainstay of Treatment is Ionotropes infusion ….... DOBUTAMINE Hypovolemic shock: Mainstay of treatment is Fluid infusion Hemorrhagic shock... Blood transfusion Obstructive Shock: Mainstay of treatment is Relieve obstruction Tension Pneumothorax: Emergency Needle decompression followed by immediate Tube thoracostomy (chest intubation) Pericardial Tamponade: Pericardiocentesis Avoid it --if due to aortic dissection or myocardial rupture Anaphylactic: Mainstay of Treatment is Epinephrine Neurogenic: Fluid resuscitation First-line therapy  Avoid aggressive fluid boluses in patients with poor fluid responsiveness, because of the risk of fluid overload Vasopressors: commonly required as shock is often refractory to fluids Lesions above T6: Consider Norepinephrine or Dopamine Lesions below T6: Consider Phenylephrine Reference Bailey and Love’s Short Practice of Surgery 26th Edition Case 2: A 34-year-old woman presents to the ER after dining at a restaurant where shortly after eating the first few bites of her meal, she became anxious, diaphoretic, began wheezing, noted diffuse pruritic rash, nausea, and a sensation of her “throat closing off”. She is currently hypotensive, tachycardic and ill appearing. What this patient is suffering from? Hypovolemic shock Vasovagal syncope Allergic asthma Anaphylactic shock Case 1 A 50-year-old male patient, with history of hypertension, presents to the ER with abrupt onset of sharp stabbing chest pain radiating through and through to the back. The pt is hypotensive, tachycardic, afebrile, with cool but dry skin. What’s the initial management for this patient? Give appropriate antibiotics Get CT scan abdomen done Start resuscitation Prepare for urgent cholecystectomy Thank You