13. Stabilization Before Anesthesia Flashcards

1
Q

What does a preanesthetic exam entail?

A

review medical record
take a complete hx
perform thorough PE
ensure vital signs are normal as possible prior to anesthesia
collect results of diagnostics tests
any abnormalities should be identified and corrected

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2
Q

What should you focus on when doing a PE?

A

Cardiovasculr, respiratory and neurological systems
ensure they are normal - these systems keep the animal alive
these systems are monitored closely under anesthesia

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3
Q

What is included in the cardiovascular system?

A

pule rate and quality
assess peripheral pulses and observe any pulse deficits
auscultate heart sounds and rate - Pulmonic, atrial, mitral (left), tricuspid (right)
MM color, CRT and skin tent

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4
Q

What is included in our respiratory system?

A

watch breathing, signs of dyspnea, MM color, auscultation of lung fields AND trachea, palpate trachea - elicit cough, body position, airway abnormalities for tracheal intubation

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5
Q

What entails the neurological examinations?

A

distance exam - observe normal behaviour
mentation
interaction w/ surroundings
posture and gait
cranial nerve and spinal reflexes
head tilt
abnormal pupil size and difference btw eyes
seizures
paralysis/paresis

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6
Q

What are other systems we should look at before anesthesia?

A

presenve of V/D, or loss of fluids
PU/PD, possible sites of hemorrhage - fractured bones
injury/dz of thorax: pneumo/hemo/pyothorax, pulmonary edema, pulmonary contusions, myocardial bruising and arrhythmias
Gastric dilation volvulus
elyte abnormalities - urethral obstruction, pain

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7
Q

What are some diagnostics tests to run before anesthesia?

A

minimum data base - healthy elective procedure (pcv, tp, bg, bun)
full BW - CBC and chem panel (recommended in patients >5yo) - assess kidney and liver func, elyte disturbances - endocrine dz
trauma patients: thoracic and abdominal rads, AFAST/TFAST (abdominal and thoracic focused assessment w/ sonography for trauma, triage and tracking), ECG

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8
Q

What is VIP?

A

main goal is to restore tissue oxygen delivery
V = ventilation to improve oxygenation of the blood
infusion of fluids and restoration of Intravasvular volume
P = maintenance of myocardial pump function and tissue perfusion

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9
Q

What to do if ventilation is impaired?

A
  • If underlying lung disease or trauma:
  • Supplement oxygen - increase FIO2
  • If oxygenation is hindered because of low PCV due to hemorrhage:
  • Administer a blood transfusion - increase oxygen carrying capacity
    CaO2 = (1.39 x H(inc PCV)b x Sat %) + (0.003 x PaO2(INC FiO2))
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10
Q

What is normal oxygenation status?

A

normal breathing pattern + CV signs
pink MM, pule ox >96%, po2 value 5xfio (90-100mmHg when breathing room air (fio = 21%)
hypoxemia = lack of oxygen in the BLOOD
Hypoxia = lack of O in the BODY

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11
Q

What are signs of hypoxemia?

A

look @ animal
* Look at the animal:
* Panicked or collapsed (can be
hyperthermic)
* Working hard to breath
(dyspnea)
* Chest wall collapses during
inspiration
* Increased HR
* Blue color to MM
* Elbows abducted
* Neck extended
* Open mouth breathing
* Pulse oximeter reading < 90%
* PaO2 < 60 mmH

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12
Q

Why do we provide oxygen in emergency?

A

use 100% o by mask
no contraindication for immediate tx - 100% o causes inflammatory changes (toxicity) after 12hr, no problems w/ inspired O <80%
Tailor O therapy for long term management
oxygen heavier than air - important in chambers, use measurement if available

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13
Q

What is goal directed therapy?

A

provide just enough oxygen to full saturate the hemoglobin - pulse oximeter >97%, avoids giving too much oxygen and risking unnecessary lung damage
Animal is more relaxed, cardiopulmonary signs more stable
normal work of breathing while lung sheal

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14
Q

What is oxygen by facemask?

A

simple and effective admin of HIGH inspired O conc
not well tolerated by awake animals
Not useful for long term mgmt - difficult to control inspired oxygen content

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15
Q

What is flow by oxygen

A

may not be ffective, O can diffuse away from animal very quickly
awake animal always moving head
get as close as possible to nose or mouth
inspired O conc probably no more than 30%

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16
Q

What is another way besides face mask and flow by mask that you can do to enclose the head for oxygen therapy?

A

E collar w/ plastic wrap
only useful for sm dogs and cats, ensure CO2 can escape
lger dogs will not be able to lose body heat or water vapor
water will condense inside the cone
animal can become hyperthermic = inc O demand

17
Q

What are intranasal oxygen catheters?

A

awake animals may not tolerate placement, can be removed by animal
place before anesthesia recover if you anticipate Oxygen therapy might be required
bilateral nasal lines - prod higher FiO
unilateral nasal catheter still may be useful for moderate O2 therapy

18
Q

How do you place a nasal catheter?

A

select appropriate diameter tubing and premeasure to the medial canthus of the eye
connect flowmeter to sterile water chamber
water in chamber indicates O flow - DOES NOT humidity O2
lubricate catheter w/ lidocaine gel and insert into ventral meatus, secure w/ Chinese finger trap sutre or w/ tape butterfly and suture

19
Q

What are nasal prongs?

A

useful for some animals, not as useful if mouth breathing, can be dislodged, use similar oxygen flows to intra-nasal catheters

20
Q

WHat is an oxygen cage?

A

for small-med sized D/c
may lose O when open the door use port holes
MUST have a method of CO2 removal - change Co2, absorber regularly, have escape holefo r Co2 diffusion
Ambiet temperature needs to be controlled
Can alter FiO, based on requirements

21
Q

Why do we use fluids to stabalize our patients?

A

aim to restore circulating blood V asap
how fast you admin depends on patients response and underlying cause of the shock
Do not be afraid to change your fluid plan regularly or use more than one type of fluid

22
Q

What is goal directed fluid therapy?

A
  • Continually reassess your patient – looking for:
  • Improvement in mentation
  • Normalization of HR, MM color, moistness, CRT
  • Improvement in peripheral pulse quality and arterial BP
  • Restoration of urine output and specific gravity (SG)
  • Closing of wide core:periphery temperature gradients
  • Blood lactate concentration
  • Fluid choice depends on the underlying cause and what’s available:
  • Crystalloids, Colloids, Albumin, Plasma, Blood
  • Blood volume of a cat = 45 - 60 mL/kg
  • Blood volume of a dog = 60 - 90 mL/kg
23
Q

Once we give a bolus of crystalloids, how do we examine the response?

A
  • 10 – 20% blood loss (mild):
  • HR and BP should normalize
  • 20 – 40% blood loss (moderate):
  • Transient improvement
  • Repeat ¼ shock bolus of crystalloids and consider colloids (5 mL/kg)
  • > 40% blood loss (severe):
  • No response
  • Repeat crystalloid bolus; use colloids (5mL/kg) and BLOOD
24
Q

How do we stabalize a patient when they need blood transfusions?

A
  • Blood type (DEA 1.1 negative in dogs ideal; Type cats)
  • Titrate to a PCV 20 – 25% in young, healthy [Hb > 75 g/L]
  • Place large bore catheters to improve flow, blood is viscous
  • Check Ca2+ concentrations with large volumes of anticoagulated blood – binds Ca2+
    resulting in patient becoming hypocalcemic (muscle twitching)
  • To raise the PCV 1% you will need:
  • 2 mL/kg whole blood
  • 1 mL/kg pRBCs
  • Rate:
  • 0.25 mL/kg/hr for the first 30 minutes if NO reaction, increase rate to 4 – 10 mL/kg/h
25
Q

How can we give pressure support to optimize CO?

A
  • Not always possible to replace volume that is lost
  • Myocardial depressant factors released in states of shock
  • Negative inotropic effects of inflammatory mediators
  • Need INOTROPES and VASOPRESSORS for cardiovascular support
26
Q

How can we clinically assess CO and O delivery?

A
  • Physical examination:
  • Peripheral pulse quality, HR, CRT
  • Ability to maintain body temperature
  • Mentation
  • Blood Pressure Measurement:
  • MAP = (CO x SVR) + CVP
  • Tissue Perfusion:
  • Urine output is related to glomerular filtration
  • Oxygen extraction ratio
27
Q

What is the base deficit - from BG analysis - and how does it measure perfusion and O delivery?

A

from BG analysis
severe if more than -10mmol/L
In humans: -5 to -8 mmol/L on entry into emergency is associated with increased
mortality

28
Q

What is lactate - from BG analysis - how does it measure perfusion and O delivery?

A
  • Increases with switch to anaerobic metabolism (normal < 2 mmol/L)
  • Liver should normally clear excess lactate, but perfusion may be compromised
  • Failure to clear lactate 24 hrs after treatment in humans is associated with increased
    mortality
  • Dogs with a high lactate at 6 hrs after treatment are 16x more likely to not survive to
    discharge