Stabilization prior to anesthesia Flashcards
Preanesthetic exam should include
Review medical record
Take a complete history
Perform a thorough physical exam
Ensure vital signs are as normal as possible prior to anaesthesia
Collect results of diagnostic tests
Any abnormalities should be identified and corrected
Physical exam should include
Focus of cardiovascular, resp and neurological systems
Ensure they are normal – these systems keep the animal alive
These systems are monitored closet under anaesthesia
How do you look at the cardio system preop
Pulse rate and quality
Assess peripheral pulses and observe any pulse deficits
Auscultate heart sounds and rate
Pulmonic, atrial, mitral (left)
Tricuspid (right)
Mm colour and texture
CRT
Skin tent
How do you look at the resp system preop
Watch breathing
Signs of dyspnea
MM colour
Auscultation of lung fields and trachea
Palpate trachea – elicit cough
Body position
Airway abnormalities for tracheal intubation
How do you look at the neuro system preop
Distance exam – observe normal behaviour
Mentation
Interaction with surroundings
Posture and gait
Cranial nerve and spinal reflexes
Head tilt
Abnormal pupil size and difference between eyes
Seizures
paralysis/paresis
What are some minor systems to look at preop
Presence of V/D, loss of fluids
PU/PD
Possible sites of haemorrhage
Fractured bones
Injury /disease of thorax
Pneumothorax, hemothorax, pyothorax
Pulmonary edema
Pulmonary contusions
Myocardial bruising and arrhythmias
Gastric dilation volvulus
Electrolyte abnormalities – urethral obstruction
Pain
What diagnosti test should you do preop
Minimum database – healthy elective procedure
-PCV, TP, BG, BUN
Full BW – CBC and chem (recommended in patients >5yo)
-Assess kidney and liver function
- Electrolyte disturbances – endocrine disease
Trauma patient
- Thoracic and abdominal rads
- AFAST/TFAST (abdominal and thoracic focused assessment and sonography for trauma, triage and tracking)
- ECG
How do you stabilize a trauma patient
The main goal is to respite tissue and oxygen delivery
V= ventilation to improve oxygenation of the blood
I=infusion of fluids and restoration of IV volume
P=maintenance of myocardial pump function and tissue perfusion
How do you increase oxygentaion
If underlying lung disease or trauma
- Supplement oxygen - increase FIO2
Of oxygenation is hindered because of low PCV due to hemorrhage
- Administer a blood transfusion – increase oxygen carrying capacity
What is a normal oxygenation status
Normal breathing pattern
Normal cardiovascular signs
Pink MM
Paul ox >96%
PaO2 valve = 5x FIO2
90-100 mmHg when breathing room air (FIO2 =21%)
Hypoxemia = lack of O2 in the blood
Hypoxia = lack of oxygen in the body
Signs of hypoxemia
Look at the animal
Panicked or collapsed (can be hyperthermic)
Working hard to breath (dyspnea)
Chest wall collapses during inspiration
Increased HR
Blue colour to MM
Elbows abducted
Open mouth breathing
Pulse ox reading <90%
PaO2 <60mmHg
Why do we provide O2 in an emrgency
Use 100% oxygen
No contraindication for immediate treatment
100% oxygen causes inflammatory change (toxicity) after 12 hours
No problems with inspired oxygen <80%
Tailor oxygen therapy for long term management
Oxygen is heavier than air
Important in chambers
Use measurement if available
What is goal directed therapy
Provide just enough oxygen to fully 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 lungs heal
What should PaO2 be preop
PaO2 only needs to be 90-100 mmHg to fully saturate hemoglobin
Does not need to be higher
Alter the inspired oxygen concentration to provide a PaO2 of 90-100 mmHg
Is O2 by facemask helpful
Simple and effective administration of HIGH inspired oxygen concentration
Not well tolerated by awake animals
Not useful for long term management:
Difficult to control inspired oxygen content
Is flow by O2 helpful
May not be effective
Oxygen can diffuse away from animal very quickly
Awake animal always moving head
Get as close as possible to nose or mouth
Inspired oxygen concentration probably no more than 30%
What can you use if O2 face mask isnt availible
Elizabethan corollary with plastic wrap
Only useful for small dogs and cats
Ensure CO2 can escape
Larger dogs will not be able to lose body heat or water vapor
Water will condense inside the cone
Animal can become hyperthermic = increase oxygen demand
What are intranasal O2 catheters and waht are they used for
Awake animals may not tolerate placement
Can be removed by the animal
Place before anesthesia recovery if you anticipate oxygen therapy might be required
Bilateral nasal lines–produce higher FIO2
Unilateral nasal catheter still may be useful for moderate O2 therapy
how do you place a nasal catheter
Select appropriate diameter tubing and pre-measure to the medial canthus of the eye
Connect flowmeter to sterile water chamber
Water in chamber indicates oxygen flow–DOES NOT humidify O2
Lubricate catheter with lidocaine gel and insert into ventral meatus, secure with Chinese finger-trap suture or with tape butterfly and suture
Are nasal prongs useful for animals
Useful for some animals
Not as useful if mouth breathing
Can be dislodges
Use similar to oxygen flows to intranasal catheters
What is an O2 cage used for
For small-medium sized dogs and cats
May lose oxygen when open the door–use port holes
MUST have a method of CO2 removal
Change CO2 absorber regularly
Have escape hole for CO2 diffusion
Ambient temperature needs to be controlled
Can alter FIO2 based on requirements
Why do you administer fluids preop
Aim to restore circulating blood volume as soon as possible.
How fast you administer fluid(s) depends upon the patient’s response and the underlying cause(s) of the shock.
Do not be afraid to change your fluid plan regularly or use more than one type of fluid.
GOAL DIRECTED FLUID THERAPY!
What is goal directed fluid therapy
ntinually 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
What is the blood volume of cats and dogs
Blood volume of a cat = 45-60 mL/kg
Blood volume of a dog = 60-90 mL/kg
How do you replace blood loss
Examine the response to 10-20 ml/kg bolus of crystalloids
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
How do you prepare for a blood transfusion
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)
How much do you need of a blood transfusion to rraise PCV
To raise the PCV 1% you will need:
2 mL/kg whole blood
1 mL/kg pRBCs
What rate should you start a blood transfusion
0.25 mL/kg/hr for the first 30 minutes if NO reaction, increase rate to 4–10 mL/kg/hr
How do you use pressure support to optimize CO
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
Clinical assessment of CO and O2 delivery
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
Unconventional measures of perfusion and O2 delivery
BASE DEFICIT (from BG analysis)
-Severe if more than-10 mmol/L
-In humans: -5 to -8 mmol/L on entry into emergency is associated with increased mortality
LACTATE (from BG analysis)
-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
