ShockUNC Emergency MedicineMedical Student Lecture Series

Objectives DefinitionApproach to the hypotensive patientTypesSpecific treatments

Definition of ShockInadequate oxygen delivery to meet metabolic demands Results in global tissue hypoperfusion and metabolic acidosisShock can occur with a normal blood pressure and hypotension can occur without shock

Understanding ShockInadequate systemic oxygen delivery activates autonomic responses to maintain systemic oxygen deliverySympathetic nervous systemNE, epinephrine, dopamine, and cortisol releaseCauses vasoconstriction, increase in HR, and increase of cardiac contractility (cardiac output)Renin-angiotensin axisWater and sodium conservation and vasoconstrictionIncrease in blood volume and blood pressure

Understanding ShockCellular responses to decreased systemic oxygen deliveryATP depletion ion pump dysfunctionCellular edemaHydrolysis of cellular membranes and cellular deathGoal is to maintain cerebral and cardiac perfusionVasoconstriction of splanchnic, musculoskeletal, and renal blood flowLeads to systemic metabolic lactic acidosis that overcomes the bodys compensatory mechanisms

Global Tissue HypoxiaEndothelial inflammation and disruptionInability of O2 delivery to meet demandResult: Lactic acidosisCardiovascular insufficiencyIncreased metabolic demands

Multiorgan DysfunctionSyndrome (MODS)Progression of physiologic effects as shock ensuesCardiac depressionRespiratory distressRenal failureDICResult is end organ failure

ABCsCardiorespiratory monitorPulse oximetrySupplemental oxygen IV accessABG, labsFoley catheterVital signs including rectal temperatureApproach to the Patient in Shock

DiagnosisPhysical exam (VS, mental status, skin color, temperature, pulses, etc)Infectious sourceLabs:CBCChemistriesLactateCoagulation studiesCulturesABG

Further EvaluationCT of head/sinusesLumbar punctureWound culturesAcute abdominal seriesAbdominal/pelvic CT or USCortisol levelFibrinogen, FDPs, D-dimer

Approach to the Patient in ShockHistoryRecent illnessFeverChest pain, SOBAbdominal painComorbiditiesMedicationsToxins/IngestionsRecent hospitalization or surgeryBaseline mental status

Physical examinationVital SignsCNS mental statusSkin color, temp, rashes, soresCV JVD, heart soundsResp lung sounds, RR, oxygen sat, ABGGI abd pain, rigidity, guarding, reboundRenal urine output

Is This Patient in Shock?Patient looks illAltered mental statusSkin cool and mottled or hot and flushedWeak or absent peripheral pulses SBP

ShockDo you remember how to quickly estimate blood pressure by pulse?

60807090 If you palpate a pulse, you know SBP is at least this number

Goals of TreatmentABCDEAirwaycontrol work of Breathingoptimize Circulationassure adequate oxygen Deliveryachieve End points of resuscitation

AirwayDetermine need for intubation but remember: intubation can worsen hypotensionSedatives can lower blood pressurePositive pressure ventilation decreases preload May need volume resuscitation prior to intubation to avoid hemodynamic collapse

Control Work of BreathingRespiratory muscles consume a significant amount of oxygenTachypnea can contribute to lactic acidosisMechanical ventilation and sedation decrease WOB and improves survival

Optimizing CirculationIsotonic crystalloidsTitrated to:CVP 8-12 mm Hg Urine output 0.5 ml/kg/hr (30 ml/hr) Improving heart rateMay require 4-6 L of fluidsNo outcome benefit from colloids

Maintaining Oxygen DeliveryDecrease oxygen demandsProvide analgesia and anxiolytics to relax muscles and avoid shiveringMaintain arterial oxygen saturation/contentGive supplemental oxygenMaintain Hemoglobin > 10 g/dLSerial lactate levels or central venous oxygen saturations to assess tissue oxygen extraction

End Points of ResuscitationGoal of resuscitation is to maximize survival and minimize morbidityUse objective hemodynamic and physiologic values to guide therapyGoal directed approachUrine output > 0.5 mL/kg/hrCVP 8-12 mmHgMAP 65 to 90 mmHgCentral venous oxygen concentration > 70%

Persistent HypotensionInadequate volume resuscitationPneumothoraxCardiac tamponadeHidden bleedingAdrenal insufficiencyMedication allergy

Practically Speaking.Keep one eye on these patientsFrequent vitals signs:Monitor success of therapiesWatch for decompensated shockLet your nurses know that these patients are sick!

Types of Shock HypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

What Type of Shock is This?68 yo M with hx of HTN and DM presents to the ER with abrupt onset of diffuse abdominal pain with radiation to his low back. The pt is hypotensive, tachycardic, afebrile, with cool but dry skin

Types of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Hypovolemic Shock

Hypovolemic Shock

Non-hemorrhagic VomitingDiarrheaBowel obstruction, pancreatitisBurns Neglect, environmental (dehydration)Hemorrhagic GI bleedTraumaMassive hemoptysisAAA ruptureEctopic pregnancy, post-partum bleeding

Hypovolemic Shock

Hypovolemic ShockABCsEstablish 2 large bore IVs or a central lineCrystalloidsNormal Saline or Lactate RingersUp to 3 litersPRBCsO negative or cross matchedControl any bleedingArrange definitive treatment

Evaluation of Hypovolemic ShockCBCABG/lactateElectrolytesBUN, CreatinineCoagulation studiesType and cross-matchAs indicatedCXRPelvic x-rayAbd/pelvis CTChest CTGI endoscopyBronchoscopyVascular radiology

Infusion Rates AccessGravity Pressure

18 g peripheral IV 50 mL/min 150 mL/min16 g peripheral IV 100 mL/min 225 mL/min14 g peripheral IV 150 mL/min 275 mL/min8.5 Fr CV cordis 200 mL/min 450 mL/min

What Type of Shock is This?An 81 yo F resident of a nursing home presents to the ED with altered mental status. She is febrile to 39.4, hypotensive with a widened pulse pressure, tachycardic, with warm extremitiesTypes of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Septic

Septic Shock

SepsisTwo or more of SIRS criteriaTemp > 38 or < 36 CHR > 90RR > 20WBC > 12,000 or < 4,000Plus the presumed existence of infectionBlood pressure can be normal!

Septic ShockSepsis (remember definition?)Plus refractory hypotensionAfter bolus of 20-40 mL/Kg patient still has one of the following:SBP < 90 mm Hg MAP < 65 mm Hg Decrease of 40 mm Hg from baseline

Sepsis

Pathogenesis of SepsisNguyen H et al. Severe Sepsis and Septic-Shock: Review of the Literature and Emergency Department Management Guidelines. Ann Emerg Med. 2006;42:28-54.

Septic ShockClinical signs:Hyperthermia or hypothermiaTachycardiaWide pulse pressureLow blood pressure (SBP

Ancillary StudiesCardiac monitorPulse oximetryCBC, Chem 7, coags, LFTs, lipase, UAABG with lactateBlood culture x 2, urine cultureCXRFoley catheter (why do you need this?)

Treatment of Septic Shock2 large bore IVsNS IVF bolus- 1-2 L wide open (if no contraindications) Supplemental oxygenEmpiric antibiotics, based on suspected source, as soon as possible

Treatment of SepsisAntibiotics- Survival correlates with how quickly the correct drug was givenCover gram positive and gram negative bacteriaZosyn 3.375 grams IV and ceftriaxone 1 gram IV orImipenem 1 gram IVAdd additional coverage as indicatedPseudomonas- Gentamicin or CefepimeMRSA- Vancomycin Intra-abdominal or head/neck anaerobic infections- Clindamycin or Metronidazole Asplenic- Ceftriaxone for N. meningitidis, H. infuenzaeNeutropenic Cefepime or Imipenem

Persistent Hypotension If no response after 2-3 L IVF, start a vasopressor (norepinephrine, dopamine, etc) and titrate to effectGoal: MAP > 60Consider adrenal insufficiency: hydrocortisone 100 mg IV

Early Goal Directed TherapySeptic Shock Study 2001263 patients with septic shock by refractory hypotension or lactate criteriaRandomly assigned to EGDT or to standard resuscitation arms (130 vs 133)Control arm treated at clinicians discretion and admitted to ICU ASAPEGDT group followed protocol for 6 hours then admitted to ICU

Rivers E et al. Early goal-directed therapy in the treatment of severe sepsis and septic shock N Engl J Med. 2001:345:1368-1377.

Treatment AlgorithmRivers E et al. Early goal-directed therapy in the treatment of severe sepsis and septic shock N Engl J Med. 2001:345:1368-1377.

EGDT GroupFirst 6 hours in EDMore fluid (5 L vs 3.5 L)More transfusion (64.1% vs 18.5%)More dobutamine (13.7% vs 0.8%)Outcome3.8 days less in hospital2 fold less cardiopulmonary complicationsBetter: SvO2, lactate, base deficit, PHRelative reduction in mortality of 34.4%46.5% control vs 30.5% EGDT

What Type of Shock is This?A 55 yo M with hx of HTN, DM presents with crushing substernal CP, diaphoresis, hypotension, tachycardia and cool, clammy extremitiesTypes of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Cardiogenic

Cardiogenic Shock

Cardiogenic ShockSigns:Cool, mottled skinTachypnea HypotensionAltered mental statusNarrowed pulse pressureRales, murmurDefined as:SBP < 90 mmHgCI < 2.2 L/m/m2PCWP > 18 mmHg

Etiologies What are some causes of cardiogenic shock?

AMI Sepsis Myocarditis Myocardial contusion Aortic or mitral stenosis, HCM Acute aortic insufficiency

Pathophysiology of Cardiogenic ShockOften after ischemia, loss of LV functionLose 40% of LV clinical shock ensuesCO reduction = lactic acidosis, hypoxiaStroke volume is reduced Tachycardia develops as compensation Ischemia and infarction worsens

Ancillary TestsEKGCXRCBC, Chem 10, cardiac enzymes, coagulation studiesEchocardiogram

Treatment of Cardiogenic ShockGoals- Airway stability and improving myocardial pump functionCardiac monitor, pulse oximetrySupplemental oxygen, IV accessIntubation will decrease preload and result in hypotension Be prepared to give fluid bolus

Treatment of Cardiogenic ShockAMIAspirin, beta blocker, morphine, heparinIf no pulmonary edema, IV fluid challengeIf pulmonary edemaDopamine will HR and thus cardiac workDobutamine May drop blood pressureCombination therapy may be more effectivePCI or thrombolyticsRV infarctFluids and Dobutamine (no NTG)Acute mitral regurgitation or VSD Pressors (Dobutamine and Nitroprusside)

What Type of Shock is This?A 34 yo F presents to the ER after dining at a restaurant where shortly after eating the first few bites of her meal, 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. Types of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Anaphalactic

Anaphalactic Shock

Anaphylactic ShockAnaphylaxis a severe systemic hypersensitivity reaction characterized by multisystem involvement IgE mediatedAnaphylactoid reaction clinically indistinguishable from anaphylaxis, do not require a sensitizing exposureNot IgE mediated

What are some symptoms of anaphylaxis?

Anaphylactic Shock First- Pruritus, flushing, urticaria appear

Next- Throat fullness, anxiety, chest tightness, shortness of breath and lightheadedness

Finally- Altered mental status, respiratory distress and circulatory collapse

Risk factors for fatal anaphylaxis Poorly controlled asthma Previous anaphylaxis Reoccurrence rates40-60% for insect stings20-40% for radiocontrast agents10-20% for penicillinMost common causesAntibioticsInsectsFood

Anaphylactic Shock

Mild, localized urticaria can progress to full anaphylaxisSymptoms usually begin within 60 minutes of exposureFaster the onset of symptoms = more severe reactionBiphasic phenomenon occurs in up to 20% of patientsSymptoms return 3-4 hours after initial reaction has clearedA lump in my throat and hoarseness heralds life-threatening laryngeal edema

Anaphylactic Shock

Anaphylactic Shock- DiagnosisClinical diagnosisDefined by airway compromise, hypotension, or involvement of cutaneous, respiratory, or GI systemsLook for exposure to drug, food, or insectLabs have no role

ABCsAngioedema and respiratory compromise require immediate intubationIV, cardiac monitor, pulse oximetryIVFs, oxygenEpinephrineSecond lineCorticosteriodsH1 and H2 blockers

Anaphylactic Shock- Treatment

Epinephrine0.3 mg IM of 1:1000 (epi-pen) Repeat every 5-10 min as neededCaution with patients taking beta blockers- can cause severe hypertension due to unopposed alpha stimulationFor CV collapse, 1 mg IV of 1:10,000If refractory, start IV dripAnaphylactic Shock- Treatment

CorticosteroidsMethylprednisolone 125 mg IV Prednisone 60 mg POAntihistaminesH1 blocker- Diphenhydramine 25-50 mg IVH2 blocker- Ranitidine 50 mg IVBronchodilatorsAlbuterol nebulizerAtrovent nebulizerMagnesium sulfate 2 g IV over 20 minutes GlucagonFor patients taking beta blockers and with refractory hypotension1 mg IV q5 minutes until hypotension resolves

Anaphylactic Shock - Treatment

All patients who receive epinephrine should be observed for 4-6 hoursIf symptom free, discharge homeIf on beta blockers or h/o severe reaction in past, consider admissionAnaphylactic Shock - Disposition

What Type of Shock is This?A 41 yo M presents to the ER after an MVC complaining of decreased sensation below his waist and is now hypotensive, bradycardic, with warm extremitiesTypes of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Neurogenic

Neurogenic Shock

Neurogenic Shock Occurs after acute spinal cord injurySympathetic outflow is disrupted leaving unopposed vagal toneResults in hypotension and bradycardiaSpinal 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 skinShock usually lasts from 1 to 3 weeksAny injury above T1 can disrupt the entire sympathetic systemHigher injuries = worse paralysis

Neurogenic Shock

A,B,CsRemember c-spine precautionsFluid resuscitationKeep MAP at 85-90 mm Hg for first 7 daysThought to minimize secondary cord injuryIf crystalloid is insufficient use vasopressorsSearch for other causes of hypotensionFor bradycardiaAtropinePacemaker Neurogenic Shock- Treatment

Neurogenic Shock- TreatmentMethylprednisoloneUsed only for blunt spinal cord injuryHigh dose therapy for 23 hoursMust be started within 8 hoursControversial- Risk for infection, GI bleed

What Type of Shock is This?A 24 yo M presents to the ED after an MVC c/o chest pain and difficulty breathing. On PE, you note the pt to be tachycardic, hypotensive, hypoxic, and with decreased breath sounds on leftTypes of ShockHypovolemicSepticCardiogenic AnaphylacticNeurogenic Obstructive

Obstructive

Obstructive Shock

Obstructive ShockTension pneumothoraxAir trapped in pleural space with 1 way valve, air/pressure builds upMediastinum shifted impeding venous returnChest pain, SOB, decreased breath soundsNo tests needed!Rx: Needle decompression, chest tube

Obstructive ShockCardiac tamponadeBlood in pericardial sac prevents venous return to and contraction of heartRelated to trauma, pericarditis, MIBecks triad: hypotension, muffled heart sounds, JVDDiagnosis: large heart CXR, echoRx: Pericardiocentisis

Obstructive ShockPulmonary embolismVirscow triad: hypercoaguable, venous injury, venostasisSigns: Tachypnea, tachycardia, hypoxiaLow risk: D-dimerHigher risk: CT chest or VQ scanRx: Heparin, consider thrombolytics

Obstructive ShockAortic stenosisResistance to systolic ejection causes decreased cardiac functionChest pain with syncopeSystolic ejection murmurDiagnosed with echoVasodilators (NTG) will drop pressure!Rx: Valve surgery

The EndAny Questions?

ReferencesTintinalli. Emergency Medicine. 6th editionRivers et al. Early Goal-Directed Therapy in the Treatment of Severe Sepsis and Septic Shock. NEJM 2001; 345(19):1368.

*SmvO2 mixed venous oxygen saturation from a PACScvO2 central venous oxygen saturation from central line*Epi the single most important step in treatment*Methylprednisolone causes less fluid retention