Shock and Resuscitation

| In Articles | 28th May 2020

Definition

Resuscitation is the process of reviving a patient from shock.
A person is in shock when there is inadequate oxygen delivery to meet metabolic demands which results in global tissue hypoperfusion and metabolic acidosis.

Shock can occur with a normal blood pressure and hypotension can occur without shock!

To find out how to stabilise and resuscitate a person in shock have a read below.

Global tissue hypoxia

  • Endothelial inflammation and disruption
  • Inability of oxygen delivery to meet demand
  • Result: lactic acidosis, cardiovascular insufficiency and increased metabolic demands

Multiorgan Dysfunction Syndrome

  • Progression of physiologic effects as shock ensues: renal failure, disseminated intravascular coagulation (DIC), respiratory distress and cardiac depression
  • The result is end organ failure

How to approach the patient in shock?

  • Cardiorespiratory monitor
  • Pulse oximetry
  • Supplemental oxygen
  • Intravenous access
  • Blood tests such as arterial blood gases (ABG), complete blood count, coagulation, lactate, cultures
  • Foley catheter to drain urine
  • Vital signs including rectal temperature

Further evaluation

  • CT of head and sinuses
  • Lumbar puncture
  • Wound cultures
  • Acute abdominal series
  • Abdominal and pelvic CT or ultrasound
  • Cortisol level
  • Fibrinogen, Fibrin degradation products (FDPs), D-dimer

History

  • Recent illness
  • Fever
  • Chest pain
  • Abdominal pain
  • Comorbidities
  • Medications
  • Toxins/ingestions
  • Recent hospitalisation or surgery
  • Baseline mental status

Physical examination

  • Vital signs
  • Mental status
  • Skin: colour, temperature, rashes, sores
  • Cardiovascular: jugular vein distention, heart sounds
  • Respiratory: lung sounds, respiratory rate, oxygen saturation, arterial blood gases
  • Gastrointestinal: abdominal pain, rigidity, guarding, rebound
  • Renal: urine output

Is the patient in shock?

  • The patient looks ill
  • Altered mental status
  • Skin cool and mottled or hot and flushed
  • Weak and absent peripheral pulses
  • Systolic blood pressure less than 110 mmHg
  • Tachycardia

Goals of treatment

  • Airway
  • Control breathing
  • Optimise circulation
  • Adequate oxygen delivery
  • Achieve end points of resuscitation

Airway

  • Determine the need for intubation but remember that intubation can worsen hypotension
  • Sedatives can lower blood pressure
  • Positive pressure ventilation decreases preload
  • May need volume resuscitation prior to intubation to avoid hemodynamic collapse

Control breathing

  • The respiratory muscles consume a significant amount of oxygen
  • Tachypnea can contribute to lactic acidosis
  • Mechanical ventilation and sedation decrease the amount of effort used to expand the lungs (WOB) and improves survival

Optimising circulation

  • Isotonic crystalloids titrated to: central venous pressure (CVP) 8-12 mmHg, urine output 0.5ml/kg/hr (30ml/hour) and improving heart rate
  • May require 4-6 litres of fluids

Maintaining oxygen delivery

  • Decrease oxygen demands: provide analgesia and anxiolytics to relax muscles and avoid shivering
  • Maintain arterial oxygen saturation/content: give supplemental oxygen, maintain hemoglobin higher than 10 g/dL
  • Serial lactate levels or central venous oxygen saturations to assess tissue oxygen extraction

End points of resuscitation

The goal of resuscitation is to maximise survival and minimise mortality of a patient in shock!!!

  • Use objective hemodynamic and physiologic values to guide therapy
  • Goal directed approach: urine output more than 0.5 mL/kg/hr, central venous pressure (CVP) 8-12 mmHg, mean arterial pressure (MAP) 65 to 90 mmHg, central venous oxygen concentration higher than 70%

PERSISTENT HYPOTENSION

  • Inadequate volume resuscitation
  • Pneumothorax
  • Cardiac tamponade
  • Hidden bleeding
  • Adrenal insufficiency
  • Medication allergy

Types of shock

A. Hypovolemic shock

1. Non-hemorrhagic

  • Vomiting
  • Diarrhoea
  • Bowel obstruction
  • Pancreatitis
  • Burns
  • Neglect
  • Dehydration

2. Hemorrhagic

  • Gastrointestinal bleed
  • Trauma
  • Massive hemoptysis
  • Abdominal aortic aneurism
  • Ectopic pregnancy
  • Post partum bleeding

Clinical picture of a patient in hypovolemic shock

  • Altered mental status: restlessness and disorientation
  • Tachycardia - rapid heart rate
  • Dyspnea - difficult breathing
  • Obvious bleeding
  • Drop in blood pressure due to decrease in blood volume
  • Decreased urinary output

Treatment of hypovolemic shock

  • Establish 2 large bore IVs or a central line
  • Crystalloids: normal saline od lactate ringers up to 3 litres
  • Packed red blood cells (PRBCs) O negative or cross matched
  • Control any bleeding

B. Septic shock - SEPSIS - blood born infection

  • Bacteria
  • Parasites
  • Viruses
  • Trauma
  • Burns
  • Pancreatitis
  • Systemic inflammatory response syndrome (SIRS)

Criteria

  • Two or more SIRS criteria: body temperature higher than 38 or lower than 36 degrees Celsius, heart rate higher than 90, respiration rate higher than 20, white blood cells more than 12.000 or less than 4.000
  • Existence of infection
  • Blood pressure can be normal

Septic shock

  • Sepsis
  • Refractory hypotension
  • After bolus of 20-40 mL/kg patient still has one of the following: systolic BP lower than 90 mmHg, mean arterial pressure lower than 65 mmHg, decrease of 40 mmHg from baseline
  • Hyperthermia or hypothermia
  • Tachycardia
  • Wide pulse pressure
  • Mental status changes

Beware of compensated shock!!

SIRS - A clinical response arising from a nonspecific insult, with ≥ 2 of the following:

  • T > 38.3 °C or < 36 °C
  • HR > 90 beats/min
  • RR > 20/min or PaCo2 < 32
  • WBC > 12,000/mm³ or < 4,000/mm³ or > 10% bands

Sepsis - SIRS with a presumed or confirmed infectious process

Severe Sepsis - Sepsis with organ failure

Septic Shock - Refractory hypotension

SIRS = systematic inflammatory response syndrome

Evaluation of septic shock

  • Cardiac monitor
  • Pulse oximetry
  • Complete blood count, biochemical analysis
  • Arterial blood gases ABG with lactate dehydrogenase LDH
  • Blood cultures twice, urine culture
  • Chest Xray
  • Foley catheter

Treatment of septic shock

  • Two large bore IVs: normal saline 1-2 L
  • Supplemental oxygen
  • Empiric antibiotics based on suspected source as soon as possible before the specific bacteria or fungus causing the infection is known
  • Survival correlates with how quickly the correct medication is given!!
  • Cover gram positive and gram negative bacteria - Ceftriaxone 1 gram IV or Imipenem 1 gram IV
  • Add additional coverage as indicated: Pseudomonas - Gentamicin or Cefepime, MRSA - Vancomycin, intra-abdominal or head/neck anaerobic infections - Clindamycin or Metronizadole, asplenia - Ceftriaxone for N. meningitidis, H. influenzae, neutropenic - Cefepime or Imipenem

PERSISTENT HYPOTENSION

  • If no response after 2-3 litres of IV fluids, start a vasopressor -Norepinephrine, Dopamine
  • Goal: MAP higher than 60
  • Consider adrenal insufficiency: Hydrocortisone 100 mg IV
Adult sepsis pathway check of patient in shock, with blood pressure, respiration, heart functions to give oxygen or the right venous treatment

C. Cardiogenic shock

Causes

  • Acute myocardial infarction
  • Sepsis
  • Myocarditis
  • Myocardial contusion
  • Aortic or mitral stenosis
  • Hypertrophic cardiomyopathy
  • Acute aortic insufficiency

Signs

  • Systolic blood pressure lower than 90 mmHg
  • Cardiac index CI less than 2.2 L/m/m2
  • Pulmonary catheter wedge pressure PCWP higher than mmHg
  • Cool, mottled skin
  • Tachypnea
  • Altered mental status
  • Narrowed pulse pressure
  • Rales, murmur

CI (Cardiac index) is a cardiodynamic measure, based on the cardiac output, which is the amount of blood the left ventricle ejects into the systemic circulation in one minute. If the value of CI is less than 2.2 L/min/m2 , the patient is in cardiogenetic shock and needs resuscitation.

PCWP (pulmonary capillary wedge pressure) is the pressure measured by wedging a pulmonary catheter with an inflated balloon into a small pulmonary arterial branch. If the pressure is high may indicate failure in the left ventricle, cardiac insufficiency and the patient in shock and the need of resuscitation.

Pathophysiology

  • Often after ischemia, loss of 40% of left ventricular function: clinical shock ensues
  • Cardiac output reduction: lactic acidosis, hypoxia
  • Stroke volume is reduced: tachycardia develops as compensation, ischemia and infarction worsens

Tests

  • ECG
  • Echocardiogram
  • Chest Xray
  • Complete blood count, cardiac enzymes, coagulation studies

Treatment of cardiogenic shock

Goals: airway stability and improving myocardial pump function

  • Cardiac monitor
  • Pulse oximetry
  • Supplemental oxygen
  • IV access - be prepared to give fluid bolus
  • Intubation will decrease preload and result in hypotension
  • Acute myocardial infarction: Aspirin, Beta blocker, Morphine, Heparin, if no pulmonary edema - IV fluid challenge, if pulmonary oedema - Dopamine (may increase heart rate), Dobutamine (may drop blood pressure), Thrombolytics, percutaneous coronary intervention (PCI) - non-surgical procedure used to treat narrowing of the coronary arteries of the heart
  • Right ventricular infarction: IV fluids and Dobutamine
  • Acute mitral regurgitation or Ventricular septal defect VSD: Dobutamine and Nitroprusside

D. Anaphylactic shock

Anaphylaxis - a severe systemic hypersensitivity reaction characterised by multisystem involvement.

  • IgE mediated - anaphylactoid reaction - clinically indistinguishable from anaphylaxis, does not require a sensitizing exposure
  • Non IgE mediated
  • Mild, localised urticaria can progress to full anaphylaxis
  • Symptoms usually begin within 60 minutes of exposure
  • The faster the onset of symptoms the more severe the reaction!
  • Biphasic phenomenon occurs in up to 20% of patients: symptoms return 3-4 hours after initial reaction has cleared
  • A "lump in my throat" and "hoarseness" can be life threatening laryngeal oedema

Risk factors for fatal anaphylaxis

  • Poorly controlled asthma
  • Previous anaphylaxis

Reoccurrence rates

  • 40-60% for insect stings
  • 20-40% for radiocontrast agents
  • 10-20% for Penicillin

Most common causes

  • Antibiotics
  • Insects
  • Food

Diagnosis

  • Airway compromise
  • Hypotension
  • Involvement of cutaneous, respiratory or gastrointestinal systems
  • Look for exposure to drugs, food, insects
  • Blood tests have no role

Symptoms

  • Lightheadedness
  • Loss of consciousness
  • Confusion
  • Headache
  • Anxiety
  • Runny nose
  • Swelling of lips, tongue and throat
  • Shortness of breath
  • Wheezes or stridor
  • Hoarseness
  • Pain when swallowing
  • Cough
  • Skin hives, itchiness, flushing
  • Abdominal pain
  • Diarrhoea and or vomiting
  • Pelvic pain
  • Loss of bladder control

Treatment

  • Angioedema and respiratory compromise require immediate intubation!
  • IV fluids
  • Cardiac monitor
  • Pulse oximetry
  • Supplemental oxygen
  • Epinephrine (Adrenaline): 0.3 mg intramuscular of 1:1000 (epi-pen), repeat every 5-10 min as needed, can cause severe hypertension. For cardiovascular collapse, 1 mg intravenous of 1:10.000
  • Corticosteroids: Methylprednisolone 125 mg IV, Hydrocortisone IV/IM, Prednisone 60 mg PO
  • Antihistamines: Diphenhydramine 25-50 mg IV, Ranitidine 50 mg IV
  • Bronchodilators: Albuterol nebuliser, Atrovent nebuliser, Magnesium sulfate 2 g IV over 20 min
  • Glucagon: for patients taking beta blockers and with refractory hypotension, 1 mg IV

All patients who receive Epinephrine should be observed for 4 to 6 hours! If they are symptom free they can be discharged. If on beta blockers or had a severe reaction in the past, consider admission.

E. Neurogenic shock

  • Occurs after acute spinal cord injury
  • Sympathetic outflow is disrupted leaving unopposed vagal tone
  • Results in hypotension and bradycardia
  • Spinal shock - temporary loss of spinal reflex activity below a total or near total spinal cord injury (not the same as neurogenic shock, the terms are not interchangeable)
  • Loss of sympathetic tone results in warm and dry skin
  • Shock usually lasts from 1 to 3 weeks
  • Any injury above the T1 vertebrae can disrupt the entire sympathetic system
  • Higher injuries can result in worse paralysis!

Treatment

  • Remember cervical spine precautions
  • Fluid resuscitation
  • If crystalloid is insufficient use Vasopressors
  • Keep mean arterial pressure MAP at 85-90 mmHg for the first 7 days
  • Search for other causes of hypotension
  • For bradycardia; Atropine, pacemaker
  • Methylprednisolone: only for blunt spinal cord injury, high dose therapy for 23 hours, must be started within 8 hours

Controversial - Methylprednisolone cause infection or gastrointestinal bleed!

F. Obstructive shock

Tension pneumothorax

  • Air trapped in the pleural space with 1 way valve, air pressure builds up
  • Mediastinum is shifted impending venous return
  • Chest pain, shortness of breath, decreased breath sounds
  • No tests needed!
  • Needle decompression, chest tube

Cardiac tamponade

  • Blood in pericardial sac prevents venous return and contraction of the heart
  • Related to trauma, pericarditis, myocardial infarction
  • Beck's triad: hypotension, muffled heart sounds, jugular vein distention
  • Diagnosis: large heart on a chest Xray and echocardiography
  • Treatment: pericardiocentesis

Pulmonary embolism

  • Virchow triad: hypercoagulation, venous injury, venostasis
  • Signs: tachypnea, tachycardia, hypoxia
  • Low risk: D-dimer test
  • Higher risk: CT chest or pulmonary ventilation/perfusion VQ scan
  • Treatment: Heparin, consider Thrombolytics

Aortic stenosis

  • Resistance to systolic ejection causes decreased cardiac function
  • Chest pain with syncope
  • Systolic ejection murmur
  • Diagnosed with echocardiogram
  • Vasodilators - Nitroglycerin will drop pressure!
  • Treatment: valve replacement surgery