8. Collapse. Comparative characteristics with shock. Aethiology and pathogenesis. Role of nervous and humoral mechanisms

Collapse –(crash, failure) – one of forms of acute vascular insufficiency occurring as a result of normal correlation disorder between vascular bed capacity and blood circulating volume.

Types (by I.R.Petrov):

1. Infectious-toxic (vessels and heart injury at infections).

2. Hypoxemic.

3. Orthostatic (at body position changing from horizontal one to vertical one).

4. Haemorrhagic (some scientists consider it shock state).

5. Peptonic (only experimental).

6. Hystaminic (only under experimental conditions).

7. Pancreatic (metabolic products come from pancreas to blood and arterial pressure is reduced).

8. Enterogenic (at demping-sysndrome).

This classification is based on aethiologic principle.

Pathogenesis. Vascular tone rapid decreasing and (or) circulating blood mass reducing lead to venous flow (return) reducing to heart, arterial and central venous pressure reducing, brain hypoxy and organism vital functions inhibiting.

Comparative characteristics

Parameters	Shock	Collapse
1. Term, process essence	Nozologic unit	Syndrom, it is not separate nozologic unit
2. Aethiology	Shock is “collapse from trauma” as a result of exteroreceptors irritation	Collapse is “shock without trauma”; it is caused by intoxication as a result of interoreceptors irritation
3. Existence and dominance of the main in pathogenesis	Changings is CNS are primary	Acute weakness of vessels and heart are primary, changings in CNS are secondary ones.
4. Course peuliarities	Phasic, with rapid development	Phases absence, relatively slow development
5. Gravity dependence on arterial pressure reducing	Without direct dependence	Direct dependence, arterial pressure decreasing is shock gravity criterium
6. Consciousness state	It is preserved or darkened	Lost or darkened
7. Circulating blood volume changing	Blood volume is decreased, blood is deponated	Blood volume is normal or reduced
8. Narcosis and anaesthesia	They have preventive significance in shock initial stage	They influence negatively on collapse course
9. Protective-compensatory reactions	First of all – from CNS side, then all organism is involved	Dyspnoe, tachycardia, haemopoietic organs functions stimulation, blood mobilization from depot

Shock and collapse similarity- in development:

1. vascular insufficiency;

2. respiratory insufficiency;

3. hypoxy;

4. compensatory and pathological reactions.

Collapse humoral causative agents:

1. histamine;

2. NO;

3. prostaglanine I₂ or prostacycline;

4. noradrenaline acting through beta-2-adrenoreceptors and causing excessive vasodilation.

9. Crash-syndrome -

is a syndrome of prolonged pressure- pathological process developing in the injured as a result of long-termed (4-8 h and more) pressuring of soft tissues of extremities with parts of destroyed buildings, ground blocks et al.

3 periods: 1) early – up to 3 days – with shock phenomena dominance; 2) intermediate – 3-12 days – with renal insufficiency dominance; 3) late- (from 8-12 days up to 1-2 months), or recovery period, with local symptoms dominance.

3 main pathogenetic factors:

1. noceoceptive irritation;

2. traumatic toxemia caused by tissues autolysis toxic products absorbtion from injury locus;

3. plasma and blood loss delt with oedema and haemorrhagias in a zone of pressured or ishemized tissues (for long).