Circulatory SHOCKUnife：循环性休克查精选文档文档资料.ppt

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1、Definition,Inadequate perfusion(oxygen supply)of tissues,resulting in:Organ dysfunctionCellular and organ damageAnd if not quickly correctedDeath,Causes of Shock a quick list:,Heart AttackAnaphylaxisLoss of Circulating Blood Volume(bleeding,burns,dehydration)Venous Dilation(allergy,pain,drugs,heat s

2、troke,infection)High or Low Body Temperature,Signs of Shock,Pulse:Rapid,weak,thready TachycardiaWhy?Compensation for decreased MAP sensed by _ Baroreceptors,Signs of Shock,RespirationsShallow,irregular,laboredMay be tachypnea(increased respiratory rate.)Why?Compensation for hypoxia sensed by:Chemore

3、ceptors,Signs of Shock:MAP,Blood PressureLow,FallingHypotension is a late finding:why?Compensatory mechanisms work at first to maintain MAP,Signs of Shock,Due to hypoperfusion:Decreased“mentation”-confused,sluggish,anxiousSkin cold,mottled,Emergency Treatment,Evaluate vital signsBP,Respiration Rate,

4、Pulse Oximeter,Temp.Control bleedingPrevent loss of body heat,Causes of Shock:Classification(the real list),Low Output Circulatory FailureHypovolemic shock(too little volume)Cardiogenic shock(pump failure)Obstructive shockDistributive shock:Venous poolingHigh Output Circulatory FailureDistributive S

5、hock:Sepsis,toxic shock,anaphylaxis:,Hypovolemic Shock,CO reduced due to loss of intravascular VOLUMEReduced venous returnCausesMost often,blood loss(hemorrhage)DehydrationBurnsFluid lost into peritoneal cavity w/pancreatitisMAP=CO*TPR,Hypovolemic Shock,CO reduced due to loss of intravascular VOLUME

6、Reduced venous returnCausesMost often,blood loss(hemorrhage)DehydrationBurnsFluid lost into peritoneal cavity w/pancreatitisMAP=CO*TPR,Cardiogenic Shock,Myocardial Infarction(most frequent cause)Acute Valvular Dysfunction e.g.papillary muscle rupture post-MIArrhythmia e.g.,heart block,ventricular ta

7、chycardiaMAP=CO*TPR,Cardiogenic Shock,Myocardial Infarction(most frequent cause)Acute Valvular Dysfunction e.g.papillary muscle rupture post-MIArrhythmia e.g.,heart block,ventricular tachycardiaMAP=CO*TPR,Obstructive Shock,CO reduced by vascular obstruction:Obstruction of Venous return(vena cava syn

8、drome usually neoplasms)Compression of the heart(pericardial tamponade*)Outflow from heart(Massive pulmonary embolism,aortic dissection),Pericardial Tamponade,Life threatening condition caused by fluid(blood,effusion fluid)under pressure around the heart.Decreases CO by decreasing fillingCauses incl

9、ude pericarditis and MI,Distributive Shock,Maldistribution of flowTwo Categories:Low Output-Venous pooling due to loss of venous toneHigh Output Circulatory Failure,Venous Pooling,A Low Output Circulatory FailureOften due to spinal shock or drug overdoseBehaves like hypovolemic shockCO severely redu

10、ced because blood is pooled in peripheral veins,rather than returned to heart,Distributive Shock:High Output,CO is normal or elevated;distribution inappropriateShock is due to loss of vascular resistanceExamples:Sepsis,Toxic Shock:Bacterial endotoxin triggers vasodilationAnaphylaxisMAP=CO*TPR,Distri

11、butive Shock:High Output,CO is normal or elevated;distribution inappropriateShock is due to loss of vascular resistanceExamples:Sepsis,Toxic Shock:Bacterial endotoxin triggers vasodilationAnaphylaxisMAP=CO*TPR,Anaphylaxis,Anaphylactic Shock,Histamine triggers vasodilation,increased capillary permeab

12、ilityCan lead to low-output distributive shock,Physiological Response to Shock,MAP=CO*TPRThe pressure drop is compensated for by regulatory mechanismsThis=“Nonprogressive”/“Compensated”Shock,Additional Compensatory Mechanisms,Renin-Angiotensin MechanismAII:vasoconstrictorAldosterone:Water conservati

13、onADH:Water retention and thirst,Progressive Shock,Compensatory mechanisms inadequate to compensate for loss of blood volumeCardiac circulation compromised decreased heart function decreased flowPositive feedback cycle:Shock worsens less compensation shock worsensClotting in small vesselsVessels dilate and permeability increases,Irreversible Shock,Cardiac and other tissue irreversibly damagedCharacterized by:Decreasing cardiac functionProgressive blood vessel dilationProgressive increase in vessel permeability,