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ck 1. A few symptomes and syndromes
1
A cute circulato ry failure lead ing to inad equate tissue p erfusio n which, if p ro lo nged ,
results in irreversible o rgan failure. M o rtality is h igh w ith o ut early d iagno sis and
treatm ent.
Aetiology and pathophysiology
Hypovolaemic shock
Absolute hypovolaemia d ue to significant intravascular fluid d ep letio n:
– Internal o r external haem o rrhage: p o st- traum atic, p eri o r p o sto p erative, o bstetrical
(ecto p ic p regnancy , uterine rup ture, etc.), blo o d lo ss d ue to an und erly ing co nd itio n
(gastro intestinal ulcer, etc.). A lo ss o f greater than 3 0 % o f blo o d vo lum e in ad ults will
lead to haem o rrhagic sho ck .
– D eh y d ratio n: severe d iarrh o ea and vo m iting, intestinal o bstructio n, d iabetic
k eto acid o sis o r hy p ero sm o lar co m a, etc.
– P lasm a leak s: extensive burns, crushed lim bs, etc.
Relative hypovolaemia d ue to vaso d ilatio n w ith o ut co nco m itant increase in
intravascular vo lum e:
– A nap h y lactic reactio n: allergic reactio n to insect bites o r stings; d rugs, m ainly
neuro m uscular blo ck ers, antibio tics, acety lsalicy lic acid , co llo id so lutio ns ( d extran,
m o d ified gelatin fluid ); equine sera; vaccines co ntaining egg p ro tein; fo o d , etc.
– A cute haem o ly sis: severe m alaria, d rug p o iso ning (rare).
Septic shock
B y a co m p lex m ech anism , o ften includ ing vaso d ilatio n, h eart failure and abso lute
hy p o vo laem ia.
Cardiogenic shock
B y d ecrease o f card iac o utp ut:
– D irect injury to the m y o card ium : infarctio n, co ntusio n, traum a, p o iso ning.
– I nd irect m ech anism : arrh y th m ia, co nstrictive p ericard itis, h aem o p ericard ium ,
p ulm o nary em bo lism , tensio n p neum o tho rax, valvular d isease, severe anaem ia, beri
beri, etc.
Clinical features
Signs common to most forms of shock
– P allo r, m o ttled sk in, co ld extrem ities, sweating and thirst.
– R ap id and weak p ulse o ften o nly d etected o n m ajo r arteries (fem o ral o r caro tid ).
– L o w blo o d p ressure (B P ), narro w p ulse p ressure, B P so m etim es und etectable.
– C ap illary refill tim e (C R T ) ≥ 3 seco nd s.
– C y ano sis, d y sp no ea, tachy p no ea are o ften p resent in vary ing d egrees d ep end ing
on
the m echanism .
– C o nscio usness usually m aintained ( m o re rap id ly altered in child ren) , but anxiety ,
co nfusio n, agitatio n o r ap athy are co m m o n.
– O liguria o r anuria.
17
1
A cute circulato ry failure lead ing to inad equate tissue p erfusio n which, if p ro lo nged ,
results in irreversible o rgan failure. M o rtality is h igh w ith o ut early d iagno sis and
treatm ent.
Aetiology and pathophysiology
Hypovolaemic shock
Absolute hypovolaemia d ue to significant intravascular fluid d ep letio n:
– Internal o r external haem o rrhage: p o st- traum atic, p eri o r p o sto p erative, o bstetrical
(ecto p ic p regnancy , uterine rup ture, etc.), blo o d lo ss d ue to an und erly ing co nd itio n
(gastro intestinal ulcer, etc.). A lo ss o f greater than 3 0 % o f blo o d vo lum e in ad ults will
lead to haem o rrhagic sho ck .
– D eh y d ratio n: severe d iarrh o ea and vo m iting, intestinal o bstructio n, d iabetic
k eto acid o sis o r hy p ero sm o lar co m a, etc.
– P lasm a leak s: extensive burns, crushed lim bs, etc.
Relative hypovolaemia d ue to vaso d ilatio n w ith o ut co nco m itant increase in
intravascular vo lum e:
– A nap h y lactic reactio n: allergic reactio n to insect bites o r stings; d rugs, m ainly
neuro m uscular blo ck ers, antibio tics, acety lsalicy lic acid , co llo id so lutio ns ( d extran,
m o d ified gelatin fluid ); equine sera; vaccines co ntaining egg p ro tein; fo o d , etc.
– A cute haem o ly sis: severe m alaria, d rug p o iso ning (rare).
Septic shock
B y a co m p lex m ech anism , o ften includ ing vaso d ilatio n, h eart failure and abso lute
hy p o vo laem ia.
Cardiogenic shock
B y d ecrease o f card iac o utp ut:
– D irect injury to the m y o card ium : infarctio n, co ntusio n, traum a, p o iso ning.
– I nd irect m ech anism : arrh y th m ia, co nstrictive p ericard itis, h aem o p ericard ium ,
p ulm o nary em bo lism , tensio n p neum o tho rax, valvular d isease, severe anaem ia, beri
beri, etc.
Clinical features
Signs common to most forms of shock
– P allo r, m o ttled sk in, co ld extrem ities, sweating and thirst.
– R ap id and weak p ulse o ften o nly d etected o n m ajo r arteries (fem o ral o r caro tid ).
– L o w blo o d p ressure (B P ), narro w p ulse p ressure, B P so m etim es und etectable.
– C ap illary refill tim e (C R T ) ≥ 3 seco nd s.
– C y ano sis, d y sp no ea, tachy p no ea are o ften p resent in vary ing d egrees d ep end ing
on
the m echanism .
– C o nscio usness usually m aintained ( m o re rap id ly altered in child ren) , but anxiety ,
co nfusio n, agitatio n o r ap athy are co m m o n.
– O liguria o r anuria.
17
