Gregory A. Schmidt, MD
Clinical Professor
Pulmonary – Critical Care Medicine
July 2020
As chiefs we highly recommend watching the video for Dr. Schmidt’s lecture as he has numerous dynamic ultrasound images with clinical context. We have highlighted the lecture below and provided various other resources to build your knowledge of shock.
Learn to ask physiologic questions
Is the cardiac output low?
Is the heart empty?
Is there pump dysfunction?
Recognize the causes of shock
Know an approach to vasoactive drug infusion (earlier may be better)
Shock Definition:
Circulatory failure causing tissue hypoxia
Usually MAP is low (blood pressure is a surrogate for blood flow)
Usually global oxygen transport is low
Microvascular dysfunction may play a role
Leading to dysfunction:
AKI, Encephalopathy, lactic acidosis, respiratory failure
If the blood pressure is low. Either the systemic vascular resistance is low, or the cardiac output is low.
Is cardiac output low?
If no, vasodilatory shock
If yes, is the heart empty?
If yes, hypovolemic shock
If no, there is pump dysfunction
LV, RV, valve, pericardium, tension pneumothorax, pulmonary embolism
This question is equivalent to asking if the pulse pressure is low.
Pulse pressure is an indicator for stroke volume as the only other variable is aortic compliance which does not change on a day to day, minute to minute basis.
We have a lot of tools to determine if cardiac output is low, demonstrated above. If cardiac output is not determined to be low, then we are dealing with vasodilatory shock. If it is low, then we need to start working on the differential diagnosis for low cardiac output shock such as hemorrhagic, hypovolemic, cardiogenic (LV, RV, pericardia, Valve, PE)
Most of the time it is septic shock, but there is a differential including liver failure, vasodilatory drugs, adrenal insufficiency, pancreatitis, paost-cardiac arrest, post-op vasoplegia, thiamine deficiency. This is a state of systemic inflammation or systemic injury.
Remember that most commonly vasodilatory shock is septic, and the most important factor in determining outcome is time to antibiotics. You do not want to miss something like thiamine deficiency because the treatment is very benign. Remember to check their medication list or see the anesthesia operative report as many medications can cause systemic vasodilation.
We used to think that anyone is low they need a bolus. Many patients with hypotension and oliguria
The question of fluids versus early vasoactive medications is still yet to be determined. The goal is determine those patients that would benefit from fluid by using pulse pressure variability, passive leg raise, IVC change and avoid giving fluids to those patients that may cause harm.
Bryne et all AJRCCM 2018 demonstrated that in an animal model (septic sheep), fluids versus early vasoactive approach, the fluid arm required more norepinephrine and vasopressin doses over time with higher lactate levels compared to the early vasoactive medication arm.
There is little evidence to support large volume of fluids.
There is no harm that has been demonstrated from an early vasoactive approach
If the patient is spontaneously breathing, there are many more factors that affect IVC collapse and this measurement should be used cautiously to determine fluid responsiveness as it has not been validated in studies.
Pump Dysfucntion (complex, but can all be visualized with ECHO)
LV dysfunction
systolic
Diastolic
RV dysfunction
Tamponade
Severe valve
facility with color doppler.
Attempt a Specific Diagnosis as it will affect outcomes
Cardiogenic Shock due to MI: early revascularization will save lives.
PE shock: thrombolysis
Tamponade: pericardiostomy
Flail mitral valve: valve surgery
Tenstion ptx: Chest tube
Shoshin beriber: thiamine
Higher targets have been tested in numerous trials showing no benefit. Higher targets may have some adverse effects such as atrial fibrillation.
Negative trial, outcomes were not improved, but there was no difference between the two arms of 60 and 65 in older patients.
Shock is classified into three types: (1) hypovolemic (due to inadequate perfusion in the setting of decreased blood volume), (2) cardiogenic (due to poor perfusion from decreased cardiac function), and (3) distributive (due to loss of vascular tone).
The basic goals of management in shock, regardless of its type, are to restore perfusion as quickly as possible and to reverse the disease process leading to the shock state.
The mainstays of shock treatment include fluid administration, vasopressors, inotropes, and blood transfusion; however, diagnosing and reversing the underlying cause of shock is as important as restoring perfusion.
Rhodes A et al. Intens Care Med 2017.
The most recent version of the Surviving Sepsis Campaign guidelines for management of sepsis.
Watch this video to see the updates from the 2012 to 2016 guidelines.
Singer M et al. JAMA 2016.
Updated definitions and clinical criteria for sepsis and septic shock by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine
ADRENAL (2018): Hydrocortisone in septic shock
Annane Trial (2002): Corticosteroids in septic shock
ATHOS-3 (2017): Angiotensin II vs. placebo in vasodilatory shock
CORTICUS (2008): Hydrocortisone in septic shock
CRISTAL (2013): Colloids vs. crystalloids in shock
FEAST (2011): Fluid resuscitation in Sub-Saharan Africa
Hydrocortisone, Vitamin C, and Thiamine in Severe Sepsis and Septic Shock (2017): Hydrocortisone, Vit C, and thiamine in sepsis
IABP-SHOCK II (2012): IABP in MI and cardiogenic shock
ProMISe (2015): Multicenter EGDT trial in severe sepsis
PROWESS (2001): Activated protein C in severe sepsis
PROWESS-SHOCK (2012): Activated protein C in septic shock
Rivers Trial (2001): Early goal-directed therapy in sepsis
SEPSISPAM (2014): MAP 65-70 vs. 80-85 mmHg in sepsis
SHOCK (1999): Early PCI/CABG in MI + shock
SOAP II (2010): Dopamine vs. norepinephrine in shock
TRISS (2014): Transfusion thresholds in sepsis
VASST (2008): Vasopressin in septic shock
INTRODUCTION TO SHOCK LECTURE
Rolando Sanchez, MD
Clinical Assistant Professor
Pulmonary – Critical Care Medicine
July 2018
MANAGING SHOCK
Rolando Sanchez, MD
Clinical Assistant Professor
Pulmonary – Critical Care Medicine
Post by Roger D. Struble MD MPH
July 14 2020