8/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 1/15What Is Hypovolemic Shock: DefinitionHypovolemic shockis an urgent medical condition, which occurs when a rapid decrease of the volume ofthe intravascular fluidusually due to severe bleedingresults in inadequate perfusion of the peripheraltissues and, eventually, in multiple organ failure .Hemorrhagic shockis hypovolemic shock caused by bleeding.Typical symptoms and signs:a person does not look right, is anxious, has pale, cool and sweaty skinand weak pulse, is lethargic and may lose consciousness.Treatmentincludes stopping bleeding, intravenous fluid infusion, oxygen and drugs.Table 1. Hypovolemic shock at a glance:vital signs and first aid1,438/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 2/15Causes and Risk FactorsThe most common cause of hypovolemic shock in adults issevere bleeding,and in childrendiarrhea .Causes ofhypovolemia:Loss of bloodExternal bleeding:penetrating injury, heavy menstruation, scalp tearGastrointestinal or rectal bleeding (blood in the stool):Rupture of the esophageal varices (in chronic alcohol abuse with liver cirrhosis)Esophageal tear due to violent vomiting, mostly in alcoholics (Mallory-Weiss syndrome)Rupture of hemorrhoidsAorto-intestinal fistulaBleeding peptic (gastric or duodenal) ulcer or gastric perforation (stomach cancer) or MeckelsdiverticulumUlcerative colitisIschemic colitisIntestinal perforation (for example, in diverticulitis)Iron toxicityColorectal cancer (after age of 50)Bleeding disorders, such as hemophiliaOther causes of internal bleeding:Spleen rupture in car/motorbike accidentsRupture of the aortic aneurysm or aortic dissectionRupture of hepatic hemangiomaRetroperitoneal bleeding (anticoagulant therapy with warfarin or heparin in individuals with deepvenous thrombosis)Fracture of the pelvis or femurHemorrhagic pancreatitisDisseminated intravascular coagulation (DIC) after snake bite or in malariaMinor injuries in hemophiliaBleeding during or after surgeryPregnancy-related bleeding:Ruptured ectopic pregnancyPlacenta previaPlacental detachment (abruptio placentae)Uterine ruptureBleeding after deliveryBlood donation11111,2352311443114111328/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 3/15Loss of blood plasmaSevere burns affecting >15% skin surfaceDecreased water intakeWater lossExcessive sweatingRepeated vomitingSevere diarrhea: gastroenteritis caused by rotavirus in small children (stomach flu), choleraExcessive urination or polyuria:Diabetes mellitus , diabetic ketoacidosisDiabetes insipidusDiureticsSalt-wasting kidney diseases (polycystic kidney disease)HypercalcemiaEndocrine causes:Severe, acute thyrotoxicosis (thyroid storm) with high fever, excessive sweating and diarrheaAcute adrenal insufficiency (adrenal crisis) in acute Addisons disease with polyuria, vomiting anddiarrheaSecond spacing:The fluid moves from the blood into the second space (the space between the cells,which is also called extracellular or interstitial space) and causes edema:Hyponatremia(a decrease in osmotic pressure of the blood results in a shift of water from the bloodinto the body cells)Congestive heart failure (blood pooling in the venous system and consequent escape of water intothe interstitial tissue [edema] and a decrease of the blood volume in the arteries (arterialhypovolemia)In anaphylactic and septic shock, the permeability of the blood vessels increases, so some fluidescapes from the blood into the interstitial spaceThird spacing:Fluid accumulation in the body spaces where normally is no or only little fluid (theabdominal cavity, retroperitoneal space, lungs, pleural space, pericardial sac):Aortic dissection (blood pooling in the newly formed space in the aortic wall)Burns fluid accumulation in the skin blistersSoft tissue traumaPancreatitis pancreatic enzymes and cytokines damage the blood vessels what results in theescape of fluid from the bloodPeritonitisPulmonary edemaPleural effusionIntestinal obstruction, paralytic ileus, volvulusA decrease of oncotic pressure of the blood plasma due to low blood protein levels and2,23232,315 231521364211181815,19151538/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 4/15hypoalbuminemia can result in the escape of fluid from the blood into the body tissues and cavities:Kidney disease with nephrotic syndrome with anasarca [generalized edema]Protein malnutrition [Kwashiorkor]can result in distended bellies in starving childrenLiver cirrhosis resulting in ascites accumulation of the fluid in the abdominal cavityProtein losing enteropathyOvarian hyperstimulation syndromeSickle cell anemia with splenic sequestration, mostly in young childrenSystemic capillary leak syndromeNOTE: Many authors use the term third spacing for both second as third spacing.Differential DiagnosisThere are other types of shock and other conditions that may resemble hypovolemic shock:Distributive shockdue to massive vasodilation with an increase in the volume of the intravascularspace with insufficient volume of the existing blood to fill this space and therefore a drop of bloodpressureSeptic shock due to infectionToxic shock syndrome, mainly in women in which a tampon-associated infection with staphylococcior streptococci results in vasodilation, high fever and rash)Anaphylactic shockNeurogenic shock due to spinal cord injury above Th4 or Th6 (low blood pressure, no tachycardia,warm skin, paraplegia or tetraplegia, numbnessToxic shock (poisoning with nitroprusside, bretylium)Cardiogenic shockdue to heart failure (myocardial infarction, arrhythmia, cardiomyopathy, heart valvedisease)Obstructive shock:Cardiac tamponade (muffled heart tones, distended neck veins)Tension pneumothorax (displaced trachea, decreased breathing sounds on one side)Hemorrhagic pneumothoraxPulmonary embolismArteriovenous malformationsVasodilationas a side effect of drugs, such as barbiturates, nitrates, opiates, antihypertensives (betablockers, vasodilators)Temporary autonomic dysfunction:Orthostatic hypotensionVasovagal syncopeThe term relative hypovolemic shock can be used when the volume of the circulatory system increases due1212132320282477752,87,272,72,72727,25,269108/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 5/15to vasodilation, for example in neurogenic shock, and the volume of the blood remains the same butinsufficient to perfuse peripheral organs.PathophysiologyCompensated ShockShock is compensated until the cardiac output (CO) and systolic blood pressure (BP) remain normal and thusmanage to maintain proper perfusion of peripheral tissues.Baroreceptor reflex.Bleeding or other cause of fluid loss results in a drop of blood volume and henceblood pressure, which is detected by baroreceptors in the aortic and carotid arch. Baroreceptors activatethe sympathetic systemsympathetic nerves, which release norepinephrine (noradrenaline) and adrenalmedulla, which releases epinephrine (adrenaline), which results in the constriction of the peripheralblood vessels in the skin and increased heart contractility and heart rate. The brain, heart and kidneyarteries have an ability of autoregulation, which means they can maintain adequate blood perfusiondespite a gross reduction of the blood pressure (systolic BP 60-100 mm Hg). All these changes result inthe redirection of the blood flow from the skin, muscles and gastrointestinal tract toward the heart, brainand kidneys.Fluid retentionAtrial volume receptors sense the drop of the blood volume and stimulate the release oftheantidiuretic hormone (ADH)from the pituitary gland, which reduces water excretion throughthe kidneys.Osmoreceptors in the hypothalamus detect the increase of blood osmolality and trigger the releaseof the ADH .Decreased perfusion of the juxtaglomerular apparatus in the kidneys stimulates renin >> angiotensinI >> angiotensin II and finallyaldosteronerelease from the adrenal cortex, which causes theretention of sodium and hence water in the kidneys, which helps to maintain blood volume.Movement of fluid from intracellular and interstitial space into the blood.Bronchodilationandhyperventilationtriggered by increased sympathetic activity results in increasedoxygen delivery to the tissues.ReferencesProgressive or Decompensated ShockShock is decompensated when cardiac output and blood pressure drop to the point where they can notmaintain proper perfusion of the tissues any more. This results in decreased oxygen delivery to the tissuesand switch from aerobic to anaerobic metabolism, which results in lactate production andlactic acidosis.Irreversible Shock451,13,23,388/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 6/15Shock is irreversible when the damage of the vital organs is so extensive that death cannot be preventeddespite treatment. The patient can still survive up to three weeks after the onset of irreversible shock .Table 2. Stages(Classes, Grades) ofHypovolemic Shock; Vital SignsCompensated DecompensatedStage 1 Stage 2 Stage3Stage 4Bloodvolumeloss40%(>2,000 mL)(immediatelylifethreatening)2CardiacoutputCompensatedbyconstriction ofvascular bedLower Lower LowerSystolicbloodpressureNormal Normal 120/min >140/minPulse Normal Weak Weak Weak orabsentCapillaryrefillNormal (2sec)Delayed(>2 sec)AbsentUrineoutputNormal (>30mL/hour)20-30mL/hour40% blood loss or brain or heart involvement (coma, bradycardia)ReferenceEarly/First SymptomsClinical symptoms and signs may not be present until 10-20% of the total blood volume in adults or up to 30%in infants is lost.Thirst due to hypovolemia (hypovolemic thirst) can appear after 15% blood lossNauseaAnxiety, irritability, agitation, sleepiness, confusionPale, clammy skin (indehydration, especially inheat stroke, skin is initially dry and warm)Symptoms of bleeding: vomiting blood (hematemesis), blood in the stool (melena), blood in the urine,bruising, chest or back pain (rupture of the thoracic aorta), abdominal orflank pain(rupture of theabdominal aortic aneurysm, stabbing), vaginal bleeding outside of menstruation.Early SignsPaleness, excessive sweating (diaphoresis)NOTE: in heat stroke, the skin would be dry and warmDilated pupilsIncreased heart rate (tachycardia; may not occur early in patients who take beta-blockers)Weak, wide pulse, initially due to increased adrenaline release and subsequent peripheralvasoconstriction and increased diastolic blood pressureBlood pressure may not fall until about 20% blood (in infants 30%) is lost. Older people with high bloodpressure or atherosclerosis may be in the stage of decompensated shock even if their blood pressure isat 120 mm Hg or above .Increased breathing frequency (tachypnea)Capillary refill time (CRT)>2 seconds in infants, children and adults (CRT in healthy, especially in old people can beprolonged in cold ambient)>3 sec corresponds to ~10% drop of blood volumeBody weight is decreased in external bleeding and dehydration, but not changed in internal bleeding,septic, anaphylactic or toxic shock.Early signs of dehydration: poorskin turgor, sunken fontanelle in infants, decrease in body weightSigns of internal bleeding: abdominal tenderness, swelling, discoloration, guarding, bruising pattern ofGrey, Turner sign and Cullens signSigns of gastrointestinal bleeding: blood in the nose, mouth, throat or rectum (rectal examination).NOTE: In infants, early symptoms and signs of hypovolemic shock are less obvious than in adults .5353238/10/2015 Hypovolemic Shock Pathophysiology, Symptoms, Signs, Treatment | eHealthStardata:text/html;charset=utf-8,%3Cdiv%20class%3D%22summary%22%20style%3D%22margin%3A%2010px%200px%3B%20padding%3A%207px%3B%20borde 9/15Late SymptomsEarly symptoms plus the following:DizzinessFaintingWeaknessConfusionLethargyLate SignsEarly signs plus the following:Mottled, cyanotic skinIncrease of tachycardia for at least 30/min upon standing , or bradycardia; arrhythmiaIncreased breathing rate (tachypnea: >30/min) or decreased breathing rate (bradypnea: 5 seconds or absentDecreased body temperature (hypothermia)Low, narrow blood pressure (systolic pressure falls earlier than diastolic, because it is more dependenton blood volume; systolic blood pressure may not fall until 30% blood is lost).Decreased or absent urination (