Shock and Resuscitation 2 Flashcards
The delivery of oxygen to the tissues is dependent on:
– Cardiac output of the animal
– Oxygen content of arterial blood
O2 Delivery (DO2) =
Cardiac output (CO) x Oxygen content of arterial blood (CaO2)
- CO = Heart rate x Stroke volume
- CaO2 = (Hemoglobin x 1.34 x SaO2) + (PaO2 x 0.003)
what do we require for proper tissue perfusion, ie for proper CO and CaO2
CO:
– Efficient cardiac pump
– Adequate intravascular volume
– Vasomotor tone
CaO2
– Adequate hemoglobin / red cell mass
– Good lung function
Resuscitation; To do list
-Ensure patent airway & patient ventilating
>Intubate & ventilate if necessary
-Supplement O2
-Provide intravascular volume support
>Crystalloids, colloids, blood products
>Not appropriate for cardiogenic shock
-Administer pain medication
-Treat primary problem
>Correct GDV, thoracocentesis for tension pneumothorax, address hemoabdomen, etc
goal of resuscitation:
– Normalization of vital parameters
O2 Supplementation methods
- Flow by
- Oxygen hood
- Oxygen cage
- Nasal oxygen
how do we monitor oxygenation while supplementing O2
– MM colour
– Pulse oximetry
* Measures amount of O2 bound to hemoglobin
* Max 100%
* Ideal > 97-100%
* Acceptable > 93%
– Arterial blood gases
what does pulse oximetry measure? what are ideal and acceptable values?
- Measures amount of O2 bound to hemoglobin
- Max 100%
- Ideal > 97-100%
- Acceptable > 93%
most common mismanagement for patients who die from trauma
– Inadequate fluid resuscitation
* Type?
* Volume?
* Rate?
when does the interstitial/intracellular compartment need resuscitation and how do we replace fluid deficits here?
- Dehydration
- Fluid deficits replaced with crystalloids
what fluids can we use to replace deficits in the intravascular compartment? How much?
– Crystalloids
* (2/3rd will leak into the other spaces)
OR
– Colloids
– Hypertonic saline – Blood components
what is our first line therapy for IV fluid selection?
- Crystalloids
– Examples of Balanced Electrolyte Solutions - Lactated Ringers Solution (LRS)
- Plasmalyte A , Plasmalyte 148
- Normosol R
- 0.9% NaCl
Crystalloids composition
– Water, electrolytes (concentrations similar to blood)
– Solutions containing small molecules that may easily pass through blood vessels
what happens to crystalloids upon IV administration?
– ~ 1/3 remains in the intravascular space
– ~ 2/3 leaks out into the interstitium
* Volume of crystalloid administration to blood loss 3:1
Endpoint of fluid therapy for a patient in shock is:
the normalization of the vital signs rather than administration of a specific volume of fluids
- Use math to come up with volumes needed
- Recognize calculated amount is a rough estimate
how do we estimate a fluid volume for administration?
- Based on percentage of volume lost
- Hypovolemic shock noted when:
– ≥30% blood loss
– ≥10% dehydration
when do we note hypovolemic shock?
– ≥30% blood loss
– ≥10% dehydration
blood volume of dog, car, horse, and ruminant
– 80-90 ml/kg (Dog)
– 60ml/kg(Cat)
– 100 ml/kg (Horse)
– 60ml/kg(Ruminant)
how much blood loss for clinical signs or shock to be present?
Expect ≥ 30% blood loss for clinical signs of shock to be present
how much crystalloid volume required to replace blood loss?
Crystalloids - only 30% stays in the intravascular space
3x the crystalloid volume required to replace the blood loss
how do crystalloid solutions administered IV redistribute through the body?
IV > ECF > ICF
shock rate for crystalloids fluids in dog, cat, horse, ruminant:
~ 1 x blood volume
– 80-90 ml/kg (Dog)
– 60ml/kg(Cat)
– 100 ml/kg (Horse)
– 60ml/kg(Ruminant)
shock volume for 11kg dog
- 11kg dog x 90ml/kg = 990ml ~ 1L
Crystalloid Rate for shock
- As fast as necessary
- Conceptualize shock rate delivered over 1 hour
- Administer 1⁄4 dose in 15-minute increments & reassess
eg.
30 kg Dog
Shock volume ~ 90 ml/kg
2700 ml » 3 L over 1 hour
= 750 ml / 15 minutes
5 kg Cat; shock volume and timing of admin
Shock volume ~ 60 ml/kg
300 ml over 1 hour
= 75 ml / 15 minutes
is crystalloid rate for shock volume administration set in stone?
no, can increase or decrease as necessary to normalize vital signs
30kg Dog 10% dehydrated
>what is the total fluid deficit?
- Total fluid deficit = % dehydration x BW(kg)
= 10% x 30 = 10/100 x 30 = 0.1 x 30
= 3 L = 3000 ml
re-expansion of what fluid compartment critical of treating shock
intravascular
Fluid Replacement - Dehydration; what must we do? what if we have to anesthetize vs not?
- Address shock
– Shock rate fluids in 15 min increments until vital signs normalize
With Anesthesia
* Replace 1⁄2 deficits prior to induction
Without Anesthesia
* Replace remaining deficits over next 12-24 hours
* Rehydration of interstitial compartment to occur over longer time
Crystalloid Administration; Rapid intravenous fluid rates require (for dog and cat):
- Catheter:
– Large
– Short - Place the largest catheter possible
– Large dog - 18g+ catheter
– Cat - 20g catheter - Consider additional catheter placement
hypertonic saline; what is it for and how does it work?
- Hyperosmolar solution
- Many Na+ molecules draw water into the intravascular space
- Very rapid intravascular volume expansion
- Short duration of action
– As Na+ molecules are redistributed
what are colloids? what are they used for?
- Solutions containing large molecules that are trapped & stay within the blood vessels
- Provide oncotic support
- As they stay in the vessel, smaller volumes required for intravascular volume expansion
examples and properties of natural colloids
- Plasma,Blood
- Remain in the vessel
- Require collection
- May need to be thawed
examples and properties of synthetic colloids
*Examples
– Pentastarch (Canada)
– Hetastarch (US)
– Tetrastarch (Voluven)
– Dextrans
* Remain in the vessel+ draw fluid into the vessel
* Readily available
MAX daily dose for synthetic colloids (dog and cat)? how should we administer?
– 20 ml/kg/day (dog)
– 10 ml/kg/day (cat)
- Administer in 1⁄4 aliquots over 5-10 minutes
- Repeat up to 4X as necessary
- Examples:
Dog
*5 ml/kg over 5-10 minutes
*Repeat up to 4X if necessary
Cat
*2.5 ml/kg over 5-10 minutes
*Repeat up to 4X if necessary
what volume of blood should we give for a transfusion?
- 10-20 ml/kg whole blood
Transfusion triggers – red cell indices:
(dogs and cats)
– Acute anemia / blood loss
* CLINICAL SIGNS
* ~PCV <25% - dogs
* ~PCV <15-20% - cats
A drop in PCV may not be seen with acute hemorrhage
how do crystalloid requirements change when colloids, hypertonic saline or blood are used?
– Crystalloid requirements are reduced
* Approximately 1⁄2
– Will note this once animal resuscitated
Over-aggressive fluid administration may:
- Dislodge early clots
- Aggravate fluid extravasation into damaged tissues
– Lungs: pulmonary edema
– Brain: increase intracranial pressures - Contribute to excessive hemodilution
– General rule of thumb: aggressive fluid administration drops PCV and TS by 1/3
– Transfusion suggested if
* PCV acutely<25%,TS<3.5-4.0g/L
how much does aggressive fluid admin drop PCV and TS by?
1/3
PCV and TS values where transfusion is recommended
- PCV acutely < 25%, TS < 3.5-4.0g/L
do we often need the full volume calculated to treat shock with shock rate?
no, rarely
analgesia recommendation for shock
– OPIOIDS
* Mainstay of analgesia in shocky patient
* Minimal cardiovascular & respiratory depression
corticosteroid recommendations for shocky patient, and possible adverse effects
- Examples:
– Dexamethasone
– Prednisolone sodium succinate (Solu-delta-cortef)
– Methylprednisolone sodium succinate (Solu Medrol) - Pharmacological effects – Widespread cellular effect
- Adverse effects:
– Increased risk of infection
– GI ulceration
– No improvement in outcome!
when should we give antibiotics to a shocky patient?
- Administer if
– Open wounds
– Bacteremia /sepsis strong differential diagnosis
– Immunocompromised patient - Otherwise, not used routinely
Delays in resuscitation of a previously healthy patient may have what result?
may render them unresponsive to aggressive therapy later on
> decompensatory shock
what values should we monitor in a shocky patient
- Clinical Signs
– Level of consciousness
– Heart rate / rhythm
– Changes in respiratory rate / rhythm
– MM colour
– CRT
how should we monitor a shocky patient?
- Monitor for Response to Therapy
- Parameters should be re-evaluated frequently
– Every 5 – 15 minutes - Parameters should be trended & should be improving if resuscitative efforts are appropriate.
most important values to monitor during shock/ best prognostic guides:
- Ideal
– Clinical signs
– pH
– Blood lactate
– CO
– Oxygen delivery
– Oxygen consumption
>last two require invasive monitoring; impractical
other values that are good to watch
* BloodPressure
– BP is an indirect assessment of cardiac output / tissue perfusion
- Blood O2 content
– Direct PaO2
– Indirect SpO2 - PCV/TS
- Lactate
- Blood Volume
– Urinary output (palpate bladder)
> Normal 1-2 ml/kg/hr
Possible Consequences of Shock
– GI hemorrhage / ulceration
– Acute renal failure
– Bacterial translocation
– Endotoxemia / sepsis
– Disseminated intravascular coagulation (DIC) (Blood clotting abnormalities)
– Respiratory failure (ARDS)
– Multiple organ failure
