#27: Shock! A Deep Dive into Our First Intensive Topic

June 9, 2021 | By Justin Berk

Summary

Patient looking rough? Tachycardic? Hypotensive? Don’t know what to do next? Shook? Fear not: Dr. Welsh, a pediatric critical care medicine doctor and Medical Director of the Hasbro Children’s Hospital Pediatric Intensive Care Unit at Brown University. Dr. Welsh spends a golden hour with us to teach on the diagnosis, treatment, and management of septic shock, cardiogenic shock, neurogenic shock, adrenal insufficiency, and more!

Credits

• Producer, Writer, Infographic: Jessica M Kelly, MD 
• Cover Art: Chris Chui MD
• Hosts: Jessica M Kelly, MD Justin Berk MD, Chris Chui MD
• Editor:Justin Berk MD; Clair Morgan of nodderly.com
• Guest(s): Sarah S Welsch MD 

Shock Pearls

1. Patients with septic shock should receive antibiotics within 1 hours of presentation and no more than 60cc/kg of isotonic fluids. Vasoactive medications such as norepinephrine and epinephrine and should be thought about early. 
2. Patients in cardiogenic shock can be worsened by IV fluids and should be treated with attempts to improve cardiac output by decreasing afterload and increasing contractility or lusitropy, such as with milrinone and dobutamine. 
3. Trauma patients with hemorrhagic shock may have bleeding into the abdomen, pelvis, or femur. They need a type and cross and may require a massive transfusion protocol and balanced transfusions.
4. Neurogenic shock presents as hypotension, bradycardia, and peripheral vasodilation as the result of unopposed parasympathetic activity in the setting of a spinal cord injury.
5. Steroids are not routinely used in shock, but steroids may be indicated in treating shock that is refractory to multiple pressors. 

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Shock Shock Notes 

Dr. Welsch describes how shock can present in a variety of ways. She describes the many forms of shock including septic, cardiogenic, obstructive, hemorrhagic, neurogenic, and refractory shock.

Take Home Points

1. Tachycardia is an early warning sign for shock. Pay attention to the normal vital signs for the patient’s age. The normal heart rate for 12-18 year olds is less than 100. 

2. Hypotension (uncompensated shock) is a late finding in shock. Compensated shock is when tachycardia or vascular resistance are increased to prevent hypotension. 

3. Stay at the bedside and continually reassess your interventions for a patient with shock.

Septic Shock  

Presentation

Assess on physical exam for fever, tachycardia (increases cardiac output), tachypnea, perfusion, and mental status.  Know the normal vital sign ranges from neonates to adults in order to know when (and how much) to be worried about abnormal vital signs like tachycardia. 

Hypotension is an obvious but a late finding of shock in pediatrics because kids have robust hearts and compensatory mechanisms. Signs of end organ failure include altered mental status (poor oxygen delivery to the brain) and poor urine output.

The Spectrum: Systemic Inflammatory Response Syndrome (SIRS) to Shock

• SIRS is >2 of the following: hyper/hypothermia, tachycardia, bradycardia (if <1 year), tachypnea, or abnormal white blood cell count or bandemia. 
• Sepsis: SIRS + an infectious source
• Severe Sepsis: Sepsis + end organ dysfunction
• Shock: Severe sepsis + not responding to initial resuscitation 

Initial Management

Start with the ABCs. Make sure they are protecting their airway (may be altered and need to be intubated). Ensure adequate oxygenation. In septic shock, oxygen demand outstrips delivery.  

Address circulation by starting with fluid resuscitation and thinking about pressors early.  IVF will address preload problems (dehydration, poor PO intake). Fluids do not address all of the etiologies of shock. 

Obtain broad cultures (blood, urine, +/- CSF), CBC, CRP, electrolytes, CMP (transaminitis indicates end organ dysfunction), blood gas, lactate, and base deficit.  The base deficit is a calculated value that helps tell you if there are additional acids in the blood (such as lactic acid or ketones). In sepsis, a more negative base deficit indicates that there is oxygen demand that is not being met and lactic acid is being produced. For more, check out this acid-base podcast by Dr. Scott Weingart. 

Start targeted antibiotics within 1 hour of recognition of sepsis (Surviving Sepsis Campaign). Consider if your patient needs broader antibiotics (e.g., if they have fever + neutropenia). 

IV Fluids

Surviving Sepsis Campaign recommends giving IVF boluses of  20cc/kg (each bolus up to max of AL 1L) up to 3 timesand then strongly consider vasoactive medications if end organ evidence of shock persists.

The FEAST trial in Africa showed children who got more fluids in shock did worse. Consider smaller amounts if worried about cardiogenic shock and right heart failure. Give normal saline (NS), Lactated ringers (LR), or Plasma-lyte. Repeated NS boluses cause a hyperchloremic non-anion gap metabolic acidosis. Stay tuned for results from the The PRoMPT BOLUS study to see what is the best IVF to bolus with for children in septic shock. Re-assessment is key. Stay at the bedside and assess improvement of  vital signs and an age-appropriate mean arterial pressure (MAP). Closely follow skin perfusion, urination, and mental status. Expert Opinion: Bedside ultrasound of inferior vena cava (IVC) diameter and IVC/aorta ratios may be helpful.

Pressors  

Cardiac output = (Heart rate) x (Stroke Volume). Stroke volume components are preload, contractility/inotropy, and afterload. 

The ideal pressor is specific to the patient. Pick a pressor based on what will best augment the patient’s cardiac output.  Norepinephrine will increase systemic vascular resistance (increases preload). Epinephrine is used in children to help with sepsis-related myocardial dysfunction and inotropy issues.

Decreasing Metabolic Demand 

Oxygen delivery = (oxygen content in the blood) x (cardiac output). 

Think of oxygen delivery like getting a piece of mail: you need the mail in the system (arterial oxygen content) AND you need the mailman to deliver it (cardiac output).  In sepsis, metabolic demand is outstripped by the body’s ability to deliver oxygen to tissues. Anything that can decrease demand is helpful. Antipyretics decrease fever and thus decrease metabolic demand. Intubation and sedation (even if not in respiratory failure) can also decrease metabolic demand. 

Cardiogenic Shock  

Presentation

Cardiac dysfunction can present with poor perfusion/decreased pulses, hypotension, tachycardia, and hepatomegaly.  Hepatomegaly can indicate elevated right sided pressures and right sided heart dysfunction.

Causes

Sepsis-related myocardial dysfunction, viral myocarditis, congenital heart disease, post-cardiac arrest, arrhythmias (prolonged SVT), anomalous left coronary artery from the pulmonary artery (ALCAPA).

Multisystem inflammatory syndrome in children (MIS-C) is a newly recognized hyper-inflammatory condition that can present in cardiogenic shock. Consider it in children who had a COVID exposure 6-8 weeks prior. Can start with screening labs (CBC, CRP, and BMP) looking for high CRP, thrombocytopenia, leukopenia, and hyponatremia.  If abnormal, consider obtaining other labs such as troponin, BNP, d-dimer, fibrinogen, and ferritin. 

Management 

If a patient has high right sided pressures, right sided heart failure, and hepatomegaly, increasing preload with IVF will worsen the clinical picture. Ensure adequate preload (kids may be dehydrated) but don’t overdo it. 

Address inotropy and left ventricular support by decreasing afterload and increasing contractility to improve cardiac output. Dobutamine is used to help with contractility/inotropy and afterload reduction.  Milrinone is also used to help with afterload reduction, contractility/inotropy, and lusitropy. Lusitropy is diastolic relaxation that allows the ventricle to fill. 

Warm shock  (bounding pulses, skin is warm, flash capillary refill) is classically septic shock.

Cold shock (poor pulses, delayed capillary refill) is classically thought of as cardiogenic shock.

Editor’s Note: Warm and cold shock are difficult to differentiate clinically. Warm shock is a type of shock seen in pediatrics, not adults. A good starting point is to treat warm shock with norepinephrine (need the alpha-agonist to help with vasoconstriction) versus cold shock with epinephrine (need the beta-agonist activity to help cardiac output).  

Obstructive Shock  

Presentation

External compression of the heart causes the heart to be unable to deliver the cardiac output the body needs. 

Desaturations, decreased breath sounds, and narrow pulse pressure in the trauma patient raises concern for tension pneumothorax, hemothorax, pericardial effusion, and pericardial tamponade. Editor’s note: A massive pulmonary embolism is another top cause of  obstructive shock in children. 

Management 

Ultrasound can help to know if there is air or fluid present that is compressing the lungs or heart. To drain a pneumothorax or hemothorax, place a chest tube at the mid-axillary or mid-clavicular line, 4th-5th rib, above the rib to avoid neurovascular bundles.

Hemorrhagic Shock in the Trauma Patient  

Blunt abdominal organ injury and pelvic or femur fractures are places for potential blood loss.

Management

In the trauma patient, start with ABCs. Obtain trauma labs such as type and screen, CBC, electrolytes, CMP, coags, d-dimer, fibrinogen.  There are institution-specific massive transfusion protocols. Patients with hemorrhagic shock may need balanced transfusions of pRBCs, platelets, and plasma. Be sure to obtain appropriate imaging ASAP. May need a CT PAN scan (CT brain, chest, and abdomen/pelvis) depending on mental status and injuries. 

Neurogenic Shock  

The triad of hypotension, bradycardia, and peripheral vasodilation is spinal cord injury. The spinal cord can be transected or stunned with injury such as being unrestrained in a motor vehicle crash. The sympathetic pathways are injured and there is unopposed parasympathetic action, which is difficult to treat. Start with early initiation of pressors, epinephrine, atropine, or isoproterenol. 

Adrenal Crisis  

When a patient is refractory to therapy, consider adrenal insufficiency, especially in patients who have received repeated steroid courses in the setting of a recent stress such as surgery. Hyperkalemia and hyponatremia are often present. Hydrocortisone dose is usually 100mg/m2. Post-cardiac arrest can cause adrenal insufficiency. Previously healthy kids presenting in shock usually do not have adrenal insufficiency. The Surviving Sepsis Campaign recommends steroids when treating shock that is refractory to multiple pressors. 

Remember from med school Waterhouse–Friderichsen syndrome, or bleeding into the adrenal glands in the setting of bacterial infection such as Neisseria meningitidis. 

Post-op Patients

Always remember anesthesia and sedation medications can drop your systemic vascular resistance and fluids will not work effectively to fix their blood pressure. 

Links

1. OPENPediatrics: Freely available modules for many topics in pediatrics including shock.
2. Society for Critical Care Medicine: A great website with lots of resources
3. Pediatric Critical Care Medicine: A great journal for critical care topics.

Learning objectives

After listening to this episode listeners will…  

1. Recognize the early warning signs of shock
2. Differentiate different etiologies of shock by their clinical presentation 
3. Be familiar with the initial management of septic shock
4. Learn how the use of vasopressors depends on the etiology of shock

Disclosures

Dr. Welsch reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Kelly, JM, Welsch, SS, Chui C, Berk J. “Shock!”. The Cribsiders Pediatric Podcast. https:/www.thecribsiders.com/ 6/9/21