In the name of Allah,In the name of Allah,the most Beneficent,the most Beneficent,

the most Mercifulthe most Merciful

2

Shock Shock

The word shock is used differently The word shock is used differently by the medical by the medical communitycommunity and the and the general public. by the public is an general public. by the public is an intense emotional reaction to a intense emotional reaction to a stressful situation or bad news. stressful situation or bad news.

Medically, shock is defined as a Medically, shock is defined as a condition where the tissues in the condition where the tissues in the body don't receive enough oxygen body don't receive enough oxygen and nutrients to allow the cells to and nutrients to allow the cells to function. This ultimately leads to function. This ultimately leads to cellular death, progressing to organ cellular death, progressing to organ failure, and finally, if untreated, failure, and finally, if untreated, whole body failure and death.whole body failure and death.

TypesTypesHinshaw and Cox Hinshaw and Cox

classificationclassificationIt names four types of It names four types of shock: shock: Hypovolemic, Hypovolemic, Cardiogenic, Cardiogenic, Distributive Distributive Obstructive shockObstructive shockIn many patients, shock is In many patients, shock is a combination of two or a combination of two or more of these four types of more of these four types of shock shock

Stages of ShockStages of Shock shock is divided into the following three major shock is divided into the following three major

stages: stages: AA nonprogressive stagenonprogressive stage (sometimes called the (sometimes called the

compensated stagecompensated stage), in which the normal circulatory ), in which the normal circulatory compensatory mechanisms eventually cause full compensatory mechanisms eventually cause full recovery without help from outside therapy. recovery without help from outside therapy.

A A progressive stage,progressive stage, in which, without therapy, in which, without therapy, the shock becomes steadily worse until death. the shock becomes steadily worse until death.

An An irreversible stage,irreversible stage, in which the shock has in which the shock has progressed to such an extent that all forms of known progressed to such an extent that all forms of known therapy are inadequate to save the person's life, therapy are inadequate to save the person's life, even though, for even though, for

Circulatory ShockCirculatory Shock

Circulatory shockCirculatory shock means means generalized inadequate blood generalized inadequate blood flow through the body, to the flow through the body, to the extent that the body tissues are extent that the body tissues are damaged because of too little damaged because of too little flow, especially because of too flow, especially because of too little oxygen and other nutrients little oxygen and other nutrients delivered to the tissue cells. delivered to the tissue cells.

Hypovolemic shock

HypovolemiaHypovolemia means diminished means diminished blood volume. This is the most blood volume. This is the most common type of shock and based common type of shock and based on insufficient circulating on insufficient circulating volume..

Its primary cause is loss of fluid Its primary cause is loss of fluid from the from the circulation (most often " (most often "hemorrhagic shock"). Causes may shock"). Causes may include internal bleeding, include internal bleeding, traumatic bleeding, or severe , or severe burns..

Other causes Other causes Hypovolemic shock

Gastroenteritis can cause significant water can cause significant water loss from loss from vomiting and and diarrhea, and is a , and is a common cause of death in third world common cause of death in third world countries.countries.

Heat exhaustion and heat stroke is caused is caused by excessive water loss through by excessive water loss through sweating as as the body tries to cool itself.the body tries to cool itself.

Patients with Patients with infections can lose significant can lose significant amounts of water from sweating. People in amounts of water from sweating. People in diabetic ketoacidosis lose significant water lose significant water because of because of elevated blood because of because of elevated blood sugars. sugars.

Intestinal obstructionIntestinal obstruction is often a is often a cause of severely reduced plasma cause of severely reduced plasma volume. Distention of the intestine volume. Distention of the intestine in intestinal obstruction partly in intestinal obstruction partly blocks venous blood flow in the blocks venous blood flow in the intestinal walls, which increases intestinal walls, which increases intestinal capillary pressure. This in intestinal capillary pressure. This in turn causes fluid to leak from the turn causes fluid to leak from the capillaries into the intestinal walls capillaries into the intestinal walls and also into the intestinal lumen. and also into the intestinal lumen. Because the lost fluid has a high Because the lost fluid has a high protein content, the result is protein content, the result is reduced total blood plasma protein reduced total blood plasma protein as well as reduced plasma volume. as well as reduced plasma volume.

In almost all patients who have severe burns or other denuding conditions of the skin, so much plasma is lost through the denuded skin areas that the plasma volume becomes markedly reduced.

The hypovolemic shock that results from plasma loss has almost the same characteristics as the shock caused by hemorrhage, except for one additional complicating factor: the blood viscosity increases greatly as a result of increased red blood cell concentration in the remaining blood, and this exacerbates the sluggishness of blood flow.

Cardiogenic shock

This type of shock is caused by the failure This type of shock is caused by the failure of the heart to pump effectively. This can of the heart to pump effectively. This can be due to damage to the heart muscle, be due to damage to the heart muscle, most often from a large most often from a large myocardial infarction. .

Other causes of cardiogenic shock include Other causes of cardiogenic shock include arrhythmias, , cardiomyopathy, , congestive heart failure (CHF), or (CHF), or cardiac valve problems. problems.

YouTube - Atrial Fibrillation - What Is Atrial Fibrillation Video - Ab.flv

YouTube - Cardiac Arrhythmia.flv

End Result of Circulatory End Result of Circulatory Shock Shock

the shock itself breeds more shock.the shock itself breeds more shock. That is, the That is, the inadequate blood flow causes the body tissues to inadequate blood flow causes the body tissues to begin deteriorating, including the heart and begin deteriorating, including the heart and circulatory system itself. This causes an even circulatory system itself. This causes an even greater decrease in cardiac output, and a vicious greater decrease in cardiac output, and a vicious circle ensues, with progressively increasing circle ensues, with progressively increasing circulatory shock, less adequate tissue perfusion, circulatory shock, less adequate tissue perfusion, more shock, and so forth until death. It is with more shock, and so forth until death. It is with this late stage of circulatory shock that we are this late stage of circulatory shock that we are especially concerned, because appropriate especially concerned, because appropriate physiologic treatment can often reverse the physiologic treatment can often reverse the rapid slide to death rapid slide to death

YouTube - Cardiac Arrhythmia.flv

YouTube - Myocardial Infarction_1.flv

YouTube - Cardiomyopathy_1.flv

Sympathetic Reflex Sympathetic Reflex Compensations in ShockCompensations in Shock

Value of the Sympathetic Nervous Value of the Sympathetic Nervous Reflexes.Reflexes.

15 to 20 per cent 15 to 20 per cent 30 to 40 per cent 30 to 40 per cent Protection of Coronary and Protection of Coronary and

Cerebral Blood Flow by the Cerebral Blood Flow by the Reflexes.Reflexes.

Distributive shock

As in hypovolaemic shock there is an As in hypovolaemic shock there is an insufficient intravascular volume of insufficient intravascular volume of blood. This form of "relative" blood. This form of "relative" hypovolaemia is the result of dilation hypovolaemia is the result of dilation of blood vessels which diminishes of blood vessels which diminishes systemic vascular resistance. .

Septic shock

Caused by an overwhelming Caused by an overwhelming systemic infection resulting in systemic infection resulting in vasodilation leading to hypotension. leading to hypotension.

Anaphylactic shock

Caused by a severe Caused by a severe anaphylactic reaction to an to an allergen, , antigen, , drug or or foreign protein causing the foreign protein causing the release of release of histamine which which causes widespread causes widespread vasodilation, leading to vasodilation, leading to hypotension and increased hypotension and increased capillary permeability. capillary permeability.

Neurogenic shock

Neurogenic shock is the rarest form Neurogenic shock is the rarest form of shock. It is caused by of shock. It is caused by trauma to to the spinal cord resulting in the the spinal cord resulting in the sudden loss of autonomic and motor sudden loss of autonomic and motor reflexes below the injury level.reflexes below the injury level.

Without stimulation by sympathetic Without stimulation by sympathetic nervous system the vessel walls nervous system the vessel walls relax uncontrollably, resulting in a relax uncontrollably, resulting in a sudden decrease in peripheral sudden decrease in peripheral vascular resistance, leading to vascular resistance, leading to vasodilation and hypotension.vasodilation and hypotension.

Causes of Neurogenic Causes of Neurogenic Shock.Shock. Some neurogenic factors that can cause loss of vasomotor Some neurogenic factors that can cause loss of vasomotor

tone include the following: tone include the following: Deep general anesthesiaDeep general anesthesia often depresses the vasomotor often depresses the vasomotor

center enough to cause vasomotor paralysis, with resulting center enough to cause vasomotor paralysis, with resulting neurogenic shock. neurogenic shock.

Spinal anesthesia,Spinal anesthesia, especially when this extends all the way especially when this extends all the way up the spinal cord, blocks the sympathetic nervous outflow up the spinal cord, blocks the sympathetic nervous outflow from the nervous system and can be a potent cause of from the nervous system and can be a potent cause of neurogenic shock. neurogenic shock.

Brain damageBrain damage is often a cause of vasomotor paralysis. Many is often a cause of vasomotor paralysis. Many patients who have had brain concussion or contusion of the patients who have had brain concussion or contusion of the basal regions of the brain develop profound neurogenic basal regions of the brain develop profound neurogenic shock. Also, even though brain ischemia for a few minutes shock. Also, even though brain ischemia for a few minutes almost always causes extreme vasomotor stimulation, almost always causes extreme vasomotor stimulation, prolonged ischemia (lasting longer than 5 to 10 minutes) prolonged ischemia (lasting longer than 5 to 10 minutes) can cause the opposite effect-total inactivation of the can cause the opposite effect-total inactivation of the vasomotor neurons in the brain stem, with consequent vasomotor neurons in the brain stem, with consequent development of severe neurogenic shock. development of severe neurogenic shock.

Obstructive shockObstructive shock

In this situation the flow of blood is In this situation the flow of blood is obstructed which impedes obstructed which impedes circulation and can result in circulation and can result in circulatory arrest. Several circulatory arrest. Several conditions result in this form of conditions result in this form of shock.shock.

Cardiac tamponadeCardiac tamponade

in which fluid in the pericardium in which fluid in the pericardium prevents inflow of blood into the heart prevents inflow of blood into the heart (venous return). Constrictive (venous return). Constrictive pericarditis, in which the pericardium pericarditis, in which the pericardium shrinks and hardens, is similar in shrinks and hardens, is similar in presentation.presentation.

YouTube - Cardiac tamponade English version.flv

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Tension pneumothorax Tension pneumothorax

Through increased Through increased intrathoracic pressure, intrathoracic pressure, bloodflow to the heart is bloodflow to the heart is prevented (venous return). prevented (venous return).

Massive pulmonary Massive pulmonary embolismembolism

is the result of a thromboembolic is the result of a thromboembolic incident in the bloodvessels of the incident in the bloodvessels of the lungs and hinders the return of lungs and hinders the return of blood to the heart blood to the heart

YouTube - DVT _ Pulmonary Embolism.flv

Aortic stenosis Aortic stenosis

Hinders circulation by Hinders circulation by obstructing the ventricular obstructing the ventricular outflow tract outflow tract

Septic ShockSeptic Shock Septic shock Septic shock refers to a refers to a

dangerously low blood pressure dangerously low blood pressure (hypotension) that may result from (hypotension) that may result from sepsis, or infection. This can occur sepsis, or infection. This can occur through the action of a bacterial through the action of a bacterial lipopolysaccharide called lipopolysaccharide called endotoxin. endotoxin.

The mortality associated with septic The mortality associated with septic shock is presently very high, shock is presently very high, estimated at 50% to 70%.estimated at 50% to 70%.

Physiology of Treatment Physiology of Treatment in Shockin Shock

Replacement TherapyReplacement Therapy Blood and Plasma Transfusion.Blood and Plasma Transfusion. If a If a

person is in shock caused by hemorrhage, person is in shock caused by hemorrhage, the best possible therapy is usually the best possible therapy is usually transfusion of whole blood.transfusion of whole blood.

If the shock is caused by plasma loss, the If the shock is caused by plasma loss, the best therapy is administration of plasma; best therapy is administration of plasma;

when dehydration is the cause, when dehydration is the cause, administration of an appropriate electrolyte administration of an appropriate electrolyte solution can correct the shock. solution can correct the shock.

Whole blood is not always available, such as Whole blood is not always available, such as under battlefield conditions. Plasma can under battlefield conditions. Plasma can usually substitute adequately for whole blood usually substitute adequately for whole blood because it increases the blood volume and because it increases the blood volume and restores normal hemodynamics. restores normal hemodynamics.

Plasma cannot restore a normal hematocrit, but Plasma cannot restore a normal hematocrit, but the human body can usually stand a decrease in the human body can usually stand a decrease in hematocrit to about half of normal before serious hematocrit to about half of normal before serious consequences result, if cardiac output is consequences result, if cardiac output is adequate. adequate.

Sometimes plasma is unavailable. In these Sometimes plasma is unavailable. In these instances, various instances, various plasma substitutesplasma substitutes have been have been developed that perform almost exactly the same developed that perform almost exactly the same hemodynamic functions as plasma. One of these hemodynamic functions as plasma. One of these is dextran solution. is dextran solution.

dextran,dextran, a large polysaccharide polymer of a large polysaccharide polymer of glucose . Certain bacteria secrete dextran as a glucose . Certain bacteria secrete dextran as a by-product of their growth, and commercial by-product of their growth, and commercial dextran can be manufactured using a bacterial dextran can be manufactured using a bacterial culture procedure culture procedure

Dextrans of appropriate molecular size do not Dextrans of appropriate molecular size do not pass through the capillary pores and, therefore, pass through the capillary pores and, therefore, can replace plasma proteins as colloid osmotic can replace plasma proteins as colloid osmotic agents. agents.

Sympathomimetic DrugsSympathomimetic Drugs A A sympathomimetic drugsympathomimetic drug is a drug that mimics sympathetic is a drug that mimics sympathetic

stimulation. These drugs include stimulation. These drugs include norepinephrinenorepinephrine, , epinephrine epinephrine , In two types of shock, sympathomimetic drugs , In two types of shock, sympathomimetic drugs have proved to be especially beneficial. have proved to be especially beneficial.

The first of these is The first of these is neurogenic shock,neurogenic shock, Administering a sympathomimetic drug takes the place of Administering a sympathomimetic drug takes the place of

the diminished sympathetic actions and can often restore the diminished sympathetic actions and can often restore full circulatory function. full circulatory function.

The second type of shock in which sympathomimetic drugs The second type of shock in which sympathomimetic drugs are valuable is are valuable is anaphylactic shock,anaphylactic shock, in which excess in which excess histamine plays a prominent role. The sympathomimetic histamine plays a prominent role. The sympathomimetic drugs have a vasoconstrictor effect that opposes the drugs have a vasoconstrictor effect that opposes the vasodilating effect of histamine. vasodilating effect of histamine.

Sympathomimetic drugs have not proved to be very Sympathomimetic drugs have not proved to be very valuable in hemorrhagic shock. The reason is that in this valuable in hemorrhagic shock. The reason is that in this type of shock, the sympathetic nervous system is almost type of shock, the sympathetic nervous system is almost always maximally activated by the circulatory reflexes always maximally activated by the circulatory reflexes already; so much norepinephrine and epinephrine are already; so much norepinephrine and epinephrine are already circulating in the blood that sympathomimetic already circulating in the blood that sympathomimetic drugs have essentially no additional beneficial effect. drugs have essentially no additional beneficial effect.

Treatment by the Head-Down Treatment by the Head-Down Position.Position.

When the pressure falls too low in most When the pressure falls too low in most types of shock, especially in hemorrhagic types of shock, especially in hemorrhagic and neurogenic shock, placing the patient and neurogenic shock, placing the patient with the head at least 12 inches lower with the head at least 12 inches lower than the feet helps tremendously in than the feet helps tremendously in promoting venous return, thereby also promoting venous return, thereby also increasing cardiac output. This head-down increasing cardiac output. This head-down position is the first essential step in the position is the first essential step in the treatment of many types of shock. treatment of many types of shock.

Oxygen Therapy.Oxygen Therapy.

major effect of shock is too little delivery major effect of shock is too little delivery of oxygen to the tissues, giving the patient of oxygen to the tissues, giving the patient oxygen to breathe can be of benefit in oxygen to breathe can be of benefit in many instances. However, this frequently many instances. However, this frequently is far less beneficial than one might is far less beneficial than one might expect, because the problem in most expect, because the problem in most types of shock is not inadequate types of shock is not inadequate oxygenation of the blood by the lungs but oxygenation of the blood by the lungs but inadequate transport of the blood after it inadequate transport of the blood after it is oxygenated. is oxygenated.

Treatment with Glucocorticoids Treatment with Glucocorticoids (Adrenal Cortex Hormones That (Adrenal Cortex Hormones That Control Glucose Metabolism).Control Glucose Metabolism). Glucocorticoids are frequently given to Glucocorticoids are frequently given to patients in severe shock for several patients in severe shock for several reasons:reasons:

(1) increase the strength of the heart in (1) increase the strength of the heart in the late stages of shock;the late stages of shock;

(2) glucocorticoids stabilize lysosomes in (2) glucocorticoids stabilize lysosomes in tissue cells and thereby prevent release of tissue cells and thereby prevent release of lysosomal enzymes into the cytoplasm of lysosomal enzymes into the cytoplasm of the cells, thus preventing deterioration the cells, thus preventing deterioration from this source; and from this source; and

(3) glucocorticoids might aid in the (3) glucocorticoids might aid in the metabolism of glucose by the severely metabolism of glucose by the severely damaged cells. damaged cells.

Circulatory ArrestCirculatory Arrest A condition closely allied to circulatory shock is A condition closely allied to circulatory shock is

circulatory arrest, in which all blood flow stops.circulatory arrest, in which all blood flow stops. This occurs frequently on the surgical operating This occurs frequently on the surgical operating

table as a result of table as a result of cardiac arrestcardiac arrest or or ventricular ventricular fibrillationfibrillation. Ventricular fibrillation can usually be . Ventricular fibrillation can usually be stopped by strong electroshock of the heart, stopped by strong electroshock of the heart,

Cardiac arrest often results from too little Cardiac arrest often results from too little oxygen in the anesthetic gaseous mixture or from oxygen in the anesthetic gaseous mixture or from a depressant effect of the anesthesia itself. a depressant effect of the anesthesia itself.

A normal cardiac rhythm can usually be restored A normal cardiac rhythm can usually be restored by removing the anesthetic and immediately by removing the anesthetic and immediately applying cardiopulmonary resuscitation applying cardiopulmonary resuscitation procedures, while at the same time supplying the procedures, while at the same time supplying the patient's lungs with adequate quantities of patient's lungs with adequate quantities of ventilatory oxygen. ventilatory oxygen.