Shock

Shock : Pathophysiology Shock : Pathophysiology Causes & ManagementCauses & Management

Dr.Anil HaripriyaDr.Anil Haripriya

Assistant Professor SurgeryAssistant Professor Surgery

NHDC & RCNHDC & RC

IntroductionIntroduction ““Rude unhinging of machinery of life’Rude unhinging of machinery of life’

-GrossGross

Inadequate delivery of oxygen and Inadequate delivery of oxygen and nutrients to maintain normal tissue and nutrients to maintain normal tissue and cellular functioncellular function

Clinically accompanied by hypotension Clinically accompanied by hypotension

MAP < 60 mmHg in a previously MAP < 60 mmHg in a previously normotensive personnormotensive person

Types of ShockTypes of Shock

HypovolemicHypovolemic Vasodilatory (Septic)Vasodilatory (Septic) NeurogenicNeurogenic CardiogenicCardiogenic Obstructive Obstructive TraumaticTraumatic

PathophysiologyPathophysiology

Physiologic response to hypovolemia Physiologic response to hypovolemia directed directed at preservation of perfusion to vital at preservation of perfusion to vital organsorgans

- Increase cardiac contractility & - Increase cardiac contractility & peripheral peripheral vascular tone via ANSvascular tone via ANS - Hormonal response to preserve salt & - Hormonal response to preserve salt &

waterwater - Change in local micro circulation to - Change in local micro circulation to regulate regulate regional blood flow regional blood flow

Neuroendocrine Neuroendocrine responseresponse

Mediated via baro & chemo receptors Mediated via baro & chemo receptors which stimulates ANS & HPA axis which stimulates ANS & HPA axis

release of epinephrine & release of epinephrine & norepinephrinenorepinephrine

Hormonal responseHormonal responseHypothalamusHypothalamus

HyperglycemiaLypolysisGluconeogenesisGlycogenolysis

Cortisol

ACTH

CRH

Hormonal responseHormonal response Stimulation of renin angiotensin Stimulation of renin angiotensin system system

Release of ADH to conserve salt & Release of ADH to conserve salt &

waterwater

Cellular responseCellular response Inadequate delivery of oxygen & Inadequate delivery of oxygen & substrates substrates

leads to in oxidative phosphorylation & leads to in oxidative phosphorylation & ATP ATP

generationgeneration

Anaerobic respiration leads to lactic Anaerobic respiration leads to lactic acidosisacidosis

Cellular responseCellular response

Na+,K+ ATP ase activity decrease Na+,K+ ATP ase activity decrease leading to leading to accumulation of Na+ & leak of K+accumulation of Na+ & leak of K+

Cellular gene expression for Cellular gene expression for HSP,VEGF,NO HSP,VEGF,NO synthase & cytokines is also increasedsynthase & cytokines is also increased

Hypovolemic shockHypovolemic shock

M/C form of shockM/C form of shock

Due to loss of blood, plasma, Due to loss of blood, plasma, extravascular extravascular

sequestration sequestration

C/f and severity depends upon amount of C/f and severity depends upon amount of volume lost volume lost


CausesCauses - Trauma - Trauma - Severe dehydration- Severe dehydration - Burns- Burns - Intestinal obstruction- Intestinal obstruction - Perforation peritonitis- Perforation peritonitis


PhasesPhases - Compenseted- Compenseted

- Decompenseted- Decompenseted

- Irreversible- Irreversible


Mild (<20%)Mild (<20%) Moderate(20-Moderate(20-40%)40%)

Severe(>40%Severe(>40%))

Cold Cold extremitiesextremities

CRTCRT

DiaphoresisDiaphoresis

AnxietyAnxiety

Same +Same +

TachycardiaTachycardia

TachypnoeaTachypnoea

OliguriaOliguria

Postural -Postural -hypotensionhypotension

Same +Same +

HypotensionHypotension

Mental status Mental status deteriorationdeterioration

Cardiogenic shockCardiogenic shock Circulatory pump failure in setting of Circulatory pump failure in setting of adequate vascular volume adequate vascular volume

Sustained hypotension SBP < 90 mm Hg Sustained hypotension SBP < 90 mm Hg for at least 30 minutesfor at least 30 minutes

– CI < 2.2 L/min/mCI < 2.2 L/min/m22

– PAWP >15mmHgPAWP >15mmHg

Surgical importance in patients with Surgical importance in patients with chest trauma forchest trauma for

–TamponadeTamponade–Tension pneumothoraxTension pneumothorax

Cardiogenic shock Cardiogenic shock Chest painChest pain

HypotensionHypotension

ArrhythmiasArrhythmias

Beck’s triadBeck’s triad

Vasodilatory shockVasodilatory shock Characterised by peripheral vasodilatation with Characterised by peripheral vasodilatation with hypotension & resistance to T/t with hypotension & resistance to T/t with vasopressorsvasopressors

CausesCauses- Septic shock- Septic shock- Hypoxic lactic acidosis- Hypoxic lactic acidosis- CO poisoning- CO poisoning- terminal stage of cardiogenic & hemorrhagic - terminal stage of cardiogenic & hemorrhagic shockshock

Septic shockSeptic shock

Manifestation of excessive & Manifestation of excessive & inflammatory response of endogenous inflammatory response of endogenous immune mechanismimmune mechanism

Sepsis is SIRS with established focus of infection

Septic shock - severe sepsis unresponsive to continuous fluid infusion and inotropes

Septic shockSeptic shock Gram –ve bacilliGram –ve bacilli

LPS+CD14

TNF

IL-1

IL-6/IL-8

NO/PAF

Neurogenic shockNeurogenic shock

tissue perfusion as a result of loss of vasomotor tone to peripheral arterial beds

Secondary to spinal cord injury from vertebral #

- Hypotension with bradycardia- Warm extremities - Motor and sensory deficit

ManagementManagement

Initially empirical

Air way secured+ oxygenation

Two wide bore lines

I.V. fluids NS/BSS

Catheterisation

Insertion of central venous catheter

Hb, CBC, Blood sugar, urea, creatinine, electrolytes

ABG


I.V. fluid NS/RL 2-3 liters over 15-30 min

If hemodynamic instability persist then start blood transfusion & control on going heamorrhage

Ionotropic like

Dopamine 5-10microgms/Kg/min

Dobutamine 2-20microgms/Kg/min

Cardiogenic shockCardiogenic shock

Conformation of diagnosis by ECG & ECHO

Intubation & mechanical ventilation often required

Avoid fluid overload

Ionotropic support preferably Dobutamine 2-20microgms/Kg/min

USG guided pericardiocentesis

Neurogenic shockNeurogenic shock

Restoration of intravascular volume by crystalloids

Vasoconstrictor

Dopamine > 10microgms/Kg/min

Phenylephrine 0.2-2.9microgms/Kg/min

Septic shockSeptic shock Culture of body fluids

Infuse BSS 500 cc/15min monitor SBP/CVP

Repeat if CVP 8-12mmHg

Goal to have a MAP of 65 mmHg & P < 120/min

If hemodynamic instability persists start vasopressor preferrably Norepinephrine 0.02-0.25microgms/Kg/min

Broad spectrum antibiotic given

Aims of resuscitationAims of resuscitation

CVP of 8-12 mmHg/ PCWP 8-12 mmHg

MAP of > 65 mmHg

Urine output of 0.5ml/Kg/hr

Hb of 7-9 gm%

CI of > 4.2 L/Kg/m2 of BSA

End Points of End Points of resuscitationresuscitation

Resuscitation complete when oxygen debt repaid,tissue Resuscitation complete when oxygen debt repaid,tissue acidosis corrected & aerobic metabolism restored acidosis corrected & aerobic metabolism restored

Systemic ParametersSystemic Parameters

LactateLactate

Base deficitBase deficit

Tissue ParametersTissue Parameters

Gastric tonometeryGastric tonometery

Near infrared spectroscopy Near infrared spectroscopy

ConclusionConclusion Early recognition of warning signs and diagnosis in the reversible phase important for successful management of shock

Hypovolemia and sepsis account for majority of shock in surgical patients

Principles of initial resuscitation same irrespective of type of shock

Ultimate treatment of underlying cause forms cornerstone of management

Health & Medicine

Shock