Surgery Flashcards
what is shock?
- Failure to meet the metabolic needs of the cell or tissue.
- DECREASED TISSUE PERFUSION
-can be a direct consequence of etiologies such as:
HYPOVOLEMIC/HEMORRHAGIC
CARDIOGENIC
NEUROGENIC
SEPTIC (due to released of molecules or cellular products that result in cellular or endothelial activation)
-initial injury is reversible but if the injury is prolonegd enough, it becomes irreversible
What is the general approach to the management of patients in shock?
- assuring secure airway with appropriate ventilation
- control of hemorrhage
- restoration of vascular volume and tissue perfusion
What is the mainstay of treatment of hemorrhagic or hypovolemic shock?
Volume resuscitation with blood products
What processes should be prevented or monitored in hemorrhagic shock?
hypothermia
acidemia
coagulopathy
What is the mainstay of treatment of hemorrhagic or septic shock?
- fluid resuscitation
- appropriate antibiotic therapy
- control of source of infection
(drainage of infected fluid collection,
removal of infected foreign body,
debridement of devitalized tissue)
What are the classifications of shock?
hypovolemic cardiogenic septic (vasogenic) neurogenic traumatic obstructive
What is the final common pathway for profound and prolonged shock?
vasodilatory shock
What is septic shock or vasodilatory shock?
the results of dysfunction of the endothelium and vasculature secondary to circulating inflammatory mediators and cells or as a response to prolonged and severe hypoperfusion
- failure of the vascular smooth muscles to constrict appropriately
- there is peripheral dilation with resultant hypotension
What is the most frequent form of vasodilatory shock?
septic shock
What type of shock is a by product of the body’s response to disruption of the host-microbe equilibrium resulting in invasive or severe localized infection?
septic shock
What are the 2 classification of sepsis according to the magnitude of systemic inflammatory reaction?
sepsis
severe sepsis
septic shock
How does sepsis, severe sepsis, and septic shock differ from each other?
sepsis has evidence of infection and systemic signs of inflammation like fever, leukocytosis, and tachycardia.
severe sepsis is sepsis with hypoperfusion with signs of organ dysfunction (not yet hypotensive)
septic shock has more significant evidence of tissue hypoperfusion and systemic hypotension
In sepsis, prompt search of infection is necessary. What are the possible locations of infection?
- wounds (inspect all wounds)
- intravenous catheters
- blood cultures
- adjunctive imaging studies to find the location of infection or abscess that is not visible externally
Why is long term, empiric, broad spectrum antibiotic use should be minimize?
- to reduce the development of resistant organism
- to avoid complications like fungal overgrowth and antibiotic-associated colitis from overgrowth of clostridium difficile
What is the role of corticosteroid?
They are class of drugs that lowers the inflammation of the body. They also reduce the immune system activity.
What the essential management for septic shock?
- Adequate airway and ventilation (intubate if necessary)
- Fluid resuscitation with balanced salt solutions
- Empiric antibiotics that target the most likely pathogen. Switch to narrow spectrum if culture result is out.
- Percutaneous drainage or operative management for those with fluid collections, infected foreign body (artificial valve), and devitalized tissue. Antibiotic therapy may not be effective if these are present.
- Vasopressor (norepi- preferrred, then epi, then arginine vasopressin)
- Intensive insulin therapy (maintenance of blood glucose at 80-110 mg/dL) for those with persistent hypergylcemia and insulin resistance
- Use of lower tidal volume if with ARDs
- Others like antiendotoxin antibodies, anticytokines antibodies, cytokine receptor antagonist, immune enhances, NO synthase inhibitor, O2 radical scavengers)
What is the most common cause of cardiogenic shock?
acute and extensive MI
What is cardiogenic shock?
CIRCULATORY PUMP FAILURE leading to diminished forward flow with subsequent hypoxia, in the setting of adequate vascular volume
What is the hymodynamic criteria for cardiogenic shock?
sustained hypotension (SBP<90mmhg for 30 mins) reduced cardiac index (<2.2 L/min/m2) elevated PAWP (>15mmHg)
What are possible causes of cardiogenic shock?
Acute MI (most common) Free wall rupture Cardiac tamponade Acute mitral regurgitation Ventricular septal defect Arrhythmia End-stage cardiomyopathy Myocarditis Severe myocardial contusion Left ventricular flow obstruction Obstruction to ledt ventricular filling Metabolic drug reactions
What are the signs of cardiogenic shock?
hypotension cool and mottled skin depressed mental status tachycardia diminished pulses
dysrhythmia, precordial heave, distal heart tones
In evalutation of possible cardiogenic shock, other causes of hypotension must be excluded (hemorrhagic, sepsis, pulmonary embolism, and aortic dissection)
What diagnostic tools are used for confirmation of a cardiac source of shock?
ECG, echocardiography
Others like CXR, ABG, Electrolytes, CBC, and cardiac enzymes may also help.
What are the effects of dobutamine?
It has an effect on both B1 and B2 adrenergic receptors.
B1- increases cardiac output by increasing cardiac rate and contractility
B2- vasodilate vascular peripheral vascular beds, lower peripheral resistance, and lower systemic blood pressure
What inotropic supports.drugs are used in profound cardiac dysfunction?
Dobutamine Dopamine (similar effects with dobutamine but in lower doses, thus preferrable)
What are the effects of epinephrine?
stimulates both alpha and beta receptors
It increases cardiac contractility and heart rate through its actions on beta1 receptor but also vasoconstrict peripheral vessel through its action on alpha1
How would you check for the status of peripheral vasculature blood flow?
capillary refill time
peripheral pulses
urine output
What is an obstructive shock?
From mechanical obstruction of venous return
What are the causes of obstructive shock?
Pericardial tamponade Pulmonary embolus Tension pneumothorax IVC obstruction -DVT -gravid uterus on IVC -neoplasm Increases intrathoracic pressure -excess PEEP -neoplasm
What are the classic findings for tension pneumothorax?
management?
- respiratory distress
- HYPOTENSION
- diminished breath sounds over one hemithorax
- hyperresonance
- JUGULAR VENOUS DISTENSION
- SHIFT OF MEDIASTINAL STRUCTURES to the unaffected side
Pleural decompression by needle decompression at 2nd ICS midclavicular line (gush of air will be heard)
What do you call the inflammatory mediators released in response to tissue injury during a soft or bony injury?
damage-associated molecular patterns
-these are somewhat similar in pathogen-associated molecular patterns
What is a third spacing?
translocation of intravascular volume into the peritoneum, bowel, burned tissues, or crush injury sites. This is the phenomenon of fluid distribution after a major trauma involving blood loss.
this serves as the basis for the treatment of hemorrhagic shock with RBCs and lactated Ringer’s solution or isotonic saline.
What are the core principles in the management of critically injured pariten?
control of airway with proper ventilation
control of active hemorrhage
appropriate volume resuscitation with blood products with limited volume of crystalloid
recognized hypoperfusion
excessive resuscitation may exacerbate the bleeding
What are the three phases of shock?
compensated
decompensated
irreversible phase
What is the goal of neuroendocrine response (sympathetic and RAAS etc) to hemorrhage?
maintain perfusion to heart and the brain through
- PERIPHERAL VASOCONSTRICTION (SNS)
- INHIBITION OF FLUID EXCRETION (RAAS)
What are the AFFERENT SENSORS/RECEPTORS that send signal to the brain during an event of hemorrhage?
Baroreceptors (in atrium, aortic arch, carotid bodies)
Chemoreceptors (aorta, carotid bodies)
What is the normal action of normal inactivated baroreceptors?
normally it inhibits the ANS action
If sudden drop of pressure is detected by the baroreceptors, it also stops to inhibit the ANS, thus ANS actions are promoted. These include peripheral vasoconstriction.
What are the body’s cardiovascular responses to hemorrhage?
- increased cardiac rate
- venous and arterial vasoconstriction
- shunting of blood away from less essential organ like G
I - autoregulation of brain and heart makes it unaffected by ANS activation (this is to maintain adequate perfusion of blood to heart and brain)
- induces catecholamine release
- increase circulating glucose availability to peripheral tissue (HYPERGLYCEMIA and INSULIN RESISTANCE)
What are the body’s hormonal responses to hemorrhage?
- Activation of H-P-A axis (releasing cortisol and epinephrine)
- RAAS system is activated (prevent sodium excretion, thus, water excretion)
- Releasing of ADH or vasopressin by the pituitary
What cytokine is the earliest cytokine that respond to an injurious stimuli? This is produced by monocytes, macrophages and T-cells.
TNF alpha
its half-life is 90 minutues, compared to IL-1 which only has minutes
What is the function of TNF alpha once released in the bloodstream?
TNF alpha can:
- produce peripharal vasodilation
- activate other cytokines
- induce procoagulant activity
- stimulate a wide array of cellular metabolic changes
What is the half-life and function of IL-1 in shock?
Half-life is only 6 minutes.
Its function is to produce a FEBRILE RESPONSE by activating prostaglandins in the posterior hypothalamus. and causes anorexia by activating the satiety center
also augments secretion of ACTH, glucocorticoids and endorphins
stimulate release of IL2, 4, 6. 8. GM-CSF. and interferon gamma
What is the function of IL2 in shock?
activates other lymphocyte and natural killer cells
What cytokine is elevated in response to hemorrhagic shock, major operative procedures or trauma? this cytokine plays a role in the development of alveolar damage and ARDS.
IL6
What are the signs of possible intra-abdominal hemorrhage?
abdominal distension
abdominal tenderness
visible abdominal wounds
Do diagnostic ultrasound or diagnostic peritoneal lavage
What diagnostic tests should be ordered if patient came in from sustained high energy blunt trauma?
CT scan to assess for head, chest, or abdominal bleeding
What are the classic findings for cardiac tamponade?
Becks triad (hypotension, muffled heart sounds, increased JVP)
dyspnea orthopnea peripheral edema chest pain tachycardia
What the emergency management for cardiac tamponade?
pericardial decompression by pericardiocentesis
needle pericardiocentesis may not be helpful in evacuating clotted blood
What is a neurogenic shock?
refers to diminished tissue perfusion as a result of LOSS OF VASOMOTOR TONE to peripheral beds due to spinal cord injury.
This results to increased vascular capacitance, decreased venous return, and decreased cardiac output
What are the classical findings for neurogenic shock?
BRADYCARDIA HYPOTENSION cardiac dysrhythmias reduce cardiac output decreased vascular resistance
What management can be done to neurogenic shock?
secure airway and ventilation
fluid resuscitation
ADMINISTRATION OF VASOCONSTRICTOR
What are the two important goals in the treatment of shock?
adequate organ perfusion
tissue oxygenation
how would you know if resuscitation is complete in treating shock?
O2 debt is repaid
tissue acidosis is corrected (means no anaerobic metabolism occurring)
aerobic metabolism restored
How would you quantify O2 debt?
Lactate levels
Base deficits
