Rabu, 11 Februari 2009

shock

Definition :

Acute Circulatory Failure

JLow cardiac output

JReduced organ blood flow

JInadequate tissue perfusion

Shock

JHaematogenic / Hypovolaemia

JCardiogenic

JSeptic

JNeurogenic

JVasogenic

Shock

Dysfunction of :

1. The pump (heart)

2. Fluid (blood volume)

3. Arteriolar resistance vessels

4. Capacity of venous vessels

Shock

Pathophysiology

nReduction in blood volume +/- deterioration in cardiac function

nHypoperfusion leads to global derangement of body function

nBreakdown of cellular metabolism & microcirculatory homeostasis

nCardiovascular collapse

Shock

nHypovolaemic Shock

nFall in circulating blood volume

uhaemorrhage

uplasma loss in burns

uextracellular fluid in fistula, vomiting, diarrhoea

uSevere ileus / volvulus

Shock

nCardiogenic Shock

uAMI - >45% left ventricle involved

uCardiac surgery

uTamponade

uMassive pulmonary embolism

Shock

nSepticaemic Shock

nRelease of polysaccharides / protein

nGram +ve – S. aureus, S. pneumoniae

nGram –ve – E. coli, Klebsiella, Proteus, Pseudomonas

nFungi, virus, Rickettsiae

nIncreased CO, decreased peripheral vascular resistance

Clinical Manifestations

JAnxious, tired, Apathy, Exhaustion

JIntense thirst

JSkin - cold, clammy, mottled, decreased cap. flow

JDecreased core temperature

JPulse pressure

JNarrow in hypovolemic

JWidened in septic

JSystolic BP - low

Hypovolemic Shock
Recognition

JInternal (concealed)

JExternal (revealed)

Shock - Response

Inadequate organ perfusion

Jdetected by stretch receptors at aorta/carotids

Jreceptors at juxtaglomerular complex

Hormonal response

Mediated by

Jrenin-angiotensin

Jaldosterone

Jepinephrine

Haemodynamic response

1. Increase in cardiac output

Jtachycardia

Jincrease in stroke volume

2. Increase in peripheral vascular resistance

Jcutaneous & visceral

3. Transcapillary refilling response

Biochemical Changes

J-ve nitrogen balance

Jretention of Na+ & water

Jincreased excretion of K+

Janaerobic metab. - metabolic acidosis, tachypnea

Biochemical Changes

If untreated, despite the circulatory adjustments

nTissue blood flow & oxygenation inadequate

nGlobal “sick cell syndrome”

nPyruvate shunted from Krebs cycle into anaerobic pathway

nLactic acid acidosis initially intracellular becomes systemic

Biochemical Changes

Untreated

nMyocardial depression

nAltered vascular permeability – fluid leakage

nIncreased viscosity of blood, resistance to flow

Biochemical Changes

Untreated

nTissue hypoxia – vasoactive agents, myocardial depressants

nMyocardial depressant factor – ischaemic pancreas

nSevere shock – disseminated intravascular coagulation

uFurther damage

uHaemorrhagic diasthesis

Biochemical Changes

Untreated

nCardiac Output declines irreversibly

nEndothelial integrity lost, infection & septicaemia

nMultiple organ failure – respiratory, hepatic & renal

nDIVC complicates

Shock

Compensation

JHealthy adult can compensate if blood loss <>

JOld age / myocardial/resp diseases - cannot compensate

JDrugs – prevent compensation eg beta blockers

JAthletes – compensate well

Management 1

Vigorous aggressive treatment - Goals

qincrease cardiac output

qimprove tissue perfusion

q1. Resuscitate - ABCD

qTreat Primary problem

qArrest hemorrhage, drain pus, etc

qImprove ventricular filling

qAdequate fluid replacement

q2. Improve myocardial contractility

qinotropic agents eg. Dopamin, dobutamine, adrenaline

q3. Support other vital organs – ventilate, dialysis

q4. Correct acid-base imbalance & electrolyte anomalies

Haemostasis

q Pressure & packing

qany soft pack on the open wound

qpressure with finger

q Do not use a tourniquet in first aid !!

q In OT explore site of bleeding

qLocate the bleeding vessels - ligate, cauterise, etc.

qDo not injudiciously clamp tissue !

Volume Replacement

Restore Blood Volume

qSaline, Hartmans Solution

qPlasma expanders - gelatin, dextran

qPlasma

qBlood transfusion

Blood

J Avoid Blood Transfusion if possible

There are problems associated with transfusion of stored blood

Blood

Problems associated with transfusion of stored blood

qTransfusion reactions

qincompatibility

qpyrexial reactions

qallergic reactions

qantibody productions

qInfections

qThrombophlebitis

qEmbolism

qAir

qmicroaggregates

Blood

Problems associated with transfusion of stored blood Adverse Effects

qHypothermia

qBiochemical derangements

qCitrate toxicity

qHyperkalaemia

qMetabolic acidosis

qCoagulation

qNo functioning platelets

q10% V & VIII

q20% XI

Blood

Indications for transfusion

Jtrauma with severe blood loss

Jmajor operations

Jsevere burns

Jpostop. patients - severe debilitation eg. infections

Jpreop. patients - chronic anaemia, urgent operation

Jprophylactic - before op. in haemorrhagic state

Types of Blood

Homologous blood

JWhole blood / packed cells

JPlatelets

JFresh frozen plasma / other components

JType & screen

Blood

Collection

JCPD solution

Jconstant mixing to prevent clotting

Jstorage at 4’C

Jshelf life of 3 weeks

Crush Syndrome

Jmassive crushing of muscle

Joligaemic shock

Jmyoglobinaemia

Jacute renal tubular necrosis

Critical Care

Jmyocardial function

Jrespiratory function

Jrenal function

Jacid-base balance

Jcirculatory sufficiency

Jneuro-psychological environment

Jnutrition

Jinfection & bacteriology

Jpain relief

Jphysiotherapy

Respiratory Care

Preoperative evaluation

Postoperative problems

Jchanges in lung volume

Jtidal volume - decreased

Jrespiratory rate, minute ventilation increased

JVC, FRC decreased - pain

JAtelectasis

Jrestriction of cough

Jno full expansion of lungs

Respiratory Care

Postoperative problems

JVentilation - perfusion incoordination

Jmechanical disruption of chest wall

Jatelectasis

Jpulmonary edema

Jpulmonary embolus

ARDS

Jsevere trauma or major surgical procedure with large blood loss

Jsuccessful resuscitation

Jnext few hours

Jdyspnea

Jtachypnea

Jhypoxemia

JIncreased permeability pulmonary edema

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