Management of Shock Flashcards
what are the fluid compartments
what are the cations and anions of the ECF
cations: sodium
anions: chloride, bicarbonate
what are the cations and anions of the ICF
cations: potassium
anions: phosphate, protein
what is responsible for the osmolarity of the fluid in the body
electrolytes
~300 mOsm/l in dogs
~310 mOsm/l in cats
what are the reasons to give fluids (6)
1. dehydration
2. shock
- provide maintenance requirements
- treat electrolyte imbalances
- maintain oncotic pressure (colloids)
- diuresis
what fluid deficit is dehydration
deficit in total body water
loss of water but often used clinically to refer to isotonic and hypotonic losses as well
what is the maintenance requirement in cats a dog
50 ml/kg/day
what is dehydration due to
- low consumption
- pathological fluid losses
what are clinical signs of dehydration
- skin tenting
- dry mucous membranes
- sunken eyes
what is circulatory shock
global energy deficit at cellular level
what is the most common shock
hypovolemic
what are the types of shock
what fluid loss is hypovolemic shock
loss of intravascular volume
what are the causes of hypovolemic shock
- dehydration
- blood loss
- 3rd spacing of fluids (pleura, peritoneum)
what is cardiogenic shock caused by (3)
- heart disease
- cardiac tamponade
- arrhythmias
why must cardiogenic shock be differentiated from other types of shock
large fluid volume is contraindicated
how do you differentiate cardiogenic shock from other types (3)
- signalment & history
- thoracic auscultation (heart murmurs, pulmonary edema heard as crackles)
- ascites/jugular distention
what is distributive shock
cardiac function and blood volume are not affected but there is a failure of the vascular tree to allow appropriate delivery
what does distributive shock cause
- loss of vascular tone: sepsis/endotoxemia, anaphylaxis
- venous blockage of blood (obstructive shock): GDV, pulmonary thromboembolism
can you treat distributive shock where there is loss of vascular tone due to sepsis/endotoxemia with fluid
yes –> vasodilation –> BP will drop
what are the classic clinical signs of hypovolemic shock (7)
- tachycardia (sympathetic response)
- poor pulse quality due to vasoconstriction and lack of blood volume
- decreased extremity temperature
- pale mucous membranes
- prolonged CRT
- decreased mentation due to inadequate brain perfusion
- tachypnea to increase oxygen uptake (not always evident)
list areas you can feel a pulse
in mild/compensated hypovolemia what would you expect the HR, MM colour, CRT, pulse amplitude, pulse duration, metatarsal pulse palpable to be
HR: 130-150
MM colour: normal/pinker
CRT: <1 sec
pulse amplitude: increased
pulse duration: mildly decreased
metatarsal pulse palpable: easily
in moderate hypovolemia what would you expect the HR, MM colour, CRT, pulse amplitude, pulse duration, metatarsal pulse palpable to be
HR: 150-170
MM colour: pink
CRT: ~2 seconds
pulse amplitude: decreased
pulse duration: decreased
metatarsal pulse palpable: just
in severe/decompensated hypovolemia what would you expect the HR, MM colour, CRT, pulse amplitude, pulse duration, metatarsal pulse palpable to be
HR: 170-200, may become bradycardic
MM colour: white/grey
CRT: > 2 seconds
pulse amplitude: severe decreased
pulse duration: severe decrease
metatarsal pulse palpable: absent
fill out this chart
what are exemptions to the rule of clinical signs (2)
- septic (distributive) shock: due to vasodilation animals may have brick red mucous membranes and bounding pulses (of decreased duration)
- cats: may have increased heart rates in early shock but frequently present with bradycardia in more severe shock
what are pathological consequences of hypovolemic shock (3)
- low blood pressure causes activation of the sympathetic nervous system –> tachycardia & vasoconstriction
- the renin-angiotensin system is activated –> vasoconstriction & fluid retention
- hydrostatic pressure promotes movement of water by Starling’s forces from the interstitium
what % of blood volume can healthy animals tolerate
30-40%
how can shock kill animals
- lack of perfusion
- cellular hypoxia –> free radical generation –> inflammatory mediators
what occurs to the GI tract during hypovolemic shock
sympathetic activation tends to shunt blood away from GIT –> disproportionate hypoperfusion and inflammation
may amplify SIRS
may allow bacterial translocation causing sepsis
what is SIRS
a complex immune response follows involving activation of multiple inflammatory mediators throughout the body –> may lead to systemic inflammatory response syndrome
may lead to multiple organ dysfunction (MODS)
what are the aims of shock treatment
- rapid yet judicious use of fluid therapy to restore vascular volume, normalize tissue perfusion and reduce secondary injuries
- identification and control of any hemorrage is an important component of treatment in hypovolemic shock
what are the routes of administration of fluid therapy
expanding vascular space so –> IV or intraosseous access is mandatory
what is intra-osseous cannulation suitable for
small puppies, kittens
what fluid is used for shock
isotonic crystalloids
equilibrate quickly with interstitial fluids –> therefore high volumes are needed “shock dose”
what is the shock dose for cats and dogs and what is normally done
dogs: 80-90 ml/kg/hr
cats: 40-60 ml/lg/hr
but giving entire shock dose is outdated concept –> divide into 4 over 15 mins and check perfusion parameters (improvement of mentation, decrease in HR, pulse quality improved)
what are examples of isotonic replacement crystalloids and what are their components
which fluid has more Na (normal saline, ringer’s, hartmann’s)
normal saline > ringer’s > hartmann’s
which fluid has more K (normal saline, ringer’s, hartmann’s)
ringers and hartmann’s have the same amount
normal saline doesnt have any
which fluid has more Cl (normal saline, ringer’s, hartmann’s)
ringer’s > normal saline > hartmann’s
which fluid has more Ca (normal saline, ringer’s, hartmann’s)
hartmann’s > ringer’s
normal saline doesn’t have any
which fluid has lactate? (normal saline, ringer’s, hartmann’s)
hartmann’s
which fluid has the highest osmolarity (normal saline, ringer’s, hartmann’s)
ringer’s > normal saline > hartmann’s
which fluid would be of choice for a patient with metabolic acidosis
hartmann’s because it is alkalinizing
when is hartmann’s contraindicated (5)
- cerebral edema (hyperosmotic so will cause additional fluid to enter cerebral cavity)
- severe liver failure: lactate cannot be metabolized
- severe abnormalities of sodium concentration
- hyperkalemia (renal/post-renal failure) because it has K
- contains Ca: cannot be mixed with blood products, sodium bicarbonate, or hypercalcemic animals
even though Hartmann’s is contraindicated in hyperkalemia, explain why it is still okay to use in cats with uretheral blockage
it contains K but only 4mmol/l –> still dilutional
bicarbonate buffer normalizes acid bases status more rapidly than saline in cats with experiental urtheral blockage
what are the advantages of crytalloids (4)
- cheap
- physiological
- few side effects
- widely available
what are the disadvantages of crystalloids
- only transiently expand the vascular compartment
- don’t provide a replacement for albumin (oncotic support) –> important in hypoalbuminemic patients especially those with peripheral edema
what are colloid fluids and how to they expand intravascular volume
large molecules which don’t cross the vascular endothelium
high oncotic pressure act to expand and maintain intravascular volume
what is the colloid shock dose
dogs: 20ml/kg/hr
cats: 10ml/kg/hr
1/4 doses over 15 mins
what is the colloid maintanence of oncotic pressure dose
20ml/kg/day
what are common colloids
haemacel
pentastarch/tetrastarch 6%
which colloid has larger molecule size (Haemacel or pentastarch/tetrastarch 6%)
haemacel: small molecular size (~25 kDa)
pentastarch/tetrastarch 6%: larger molecule size (~200 kDa)
which colloid has a rapid volume expansion (Haemacel or pentastarch/tetrastarch 6%)
Haemacel
which colloid has a longer duration of action (Haemacel or pentastarch/tetrastarch 6%)
pentastarch/tetrastarch 6%
~60% lost after 24hrs
haemacel: ~80% lost after 24hrs
which colloid has a higher risk of coagulopathy (Haemacel or pentastarch/tetrastarch 6%)
pentastarch/tetrastarch 6%
at high doses (>20ml/kg/day or up to 50ml/kg/day with certain tetrastarches)
which colloid has a higher risk of anaphylaxis (Haemacel or pentastarch/tetrastarch 6%)
haemacel
what are the differences of crystalloids and colloids
no definitive evidence exists showing superiority of one over the other
cyrstalloids seem effect despite physiological inferiority
recent controversy with withdrawal of colloids in human med (renal complications)
when are colloids particularly useful
- hypoalbuminemia
- large patients
- poor response to crystalloids
what is hypertonic saline
7.2% NaCl
how does hypertonic saline improve hypovolemia
high osmotic gradient draws interstitial fluid into the vascular space
what volume of hypertonic saline is needed
small volumes required 4ml/kg over 10 minutes
what does hypertonic saline cause
+ ionotropy and reduce inflammation
what is hypertonic saline useful for
hypovolemic patients with head trauma
when is hypertonic saline not to be administered
in already dehydrated patients
what must you follow up with once you give hypertonic saline
crystalloids to repay the debt
can be mixed with colloids for shock resuscitation in severe cases
when are blood products not indicated
as first line treatment for shock as it cannot be administered fast enough while avoiding potential transfusion reactions
animals in shock don’t die of anemia –> lack of vascular volume
once initial resuscitation has been carried out, transfusion may be required to maintain a PCV of greater than 20-25%
what is hypotensive rescusitation
may be indicated in ongoing internal hemorrhage
restores blood pressure to acceptable limits (60 mmHg) without “popping the clot”
definitive volume restoration delayed until bleeding is surgically managed
what are additional shock therapies (5)
- broad spectrum bacteriocidal antibiotics
- GI protectants
- vasopressors/iontropes (used is severe sepsis)
- bicarbonate
- glucocorticoids (but can cause immunosuppression + GI irritation, can be useful in septic shock)
what additional monitoring is needed
- physical findings essential (mucous membranes, capillary refill time, pulse rate and quality, heart rate, respiratory rate)
- urine output (<1 ml/kg/hr could indicate hypovolemia and inadequate renal perfusion or renal failure)
- arterial blood pressure: monitor trends
- blood lactate: < 2mmol/L normal
what are mild increases of lactate
2-5 mmol/L
what are moderate increases in lactate
5-8 mmol/L
what are severe increases in lactate
>8 mmol/L
what are causes of increased plasma lactate concentrations (5)
type A
- inadequate oxygen delivery
- increased oxygen demand
type B
- inadequate oxygen utilization
- drugs/toxin (list not exhaustive)
- congenital errors of metabolism
how does inadequate oxygen delivery lead to increased lactate concnetrations (3)
- inadequate tissue perfusion
- low arterial oxygen saturation
- low hemoglobin concentration
how does increased oxygen demand lead to increased lactate concnetrations (3)
- exercise
- shivering
- seizures
how does inadequate oxygen utilization lead to increased lactate concnetrations (5)
- sepsis
- SIRS
- neoplasia
- renal failure
- diabetes mellitus
what drugs/toxins lead to increased lactate concentrations (5)
- ethylene glycol
- cyanide
- carbon monoxide
- strychnine
- acetaminophen
what are complications of fluid therapy (4)
- iatrogenic electrolyte disturbances
- overzealous use of fluids may lead to volume overload
- catheter related tissues
- complications associated with individual products (coagulopathy with colloids)
what are the signs of volume overload (7)
- chemosis
- serous nasal discharge
- increased respiratory rate
- effort and noise
- restlessness
- peripheral edema
- polyuria
- pulmonary and interstitial edema
what patients are more susceptible to volume overload
- renal disease
- cardiac disease
- hypoalbuminemia
- pulmonary contusions
