Download ANESTHETIC PROBLEMS AND EMERGENCIES

ANESTHETIC PROBLEMS
AND EMERGENCIES
CHAPTER 12
Every anesthetic procedure
has the potential to cause
death of the animal

Emergencies are uncommon and
the overwhelming majority of
patients recover from anesthesia
with no ill lasting effects
WHY,WHY,WHY
DO ANESTHETIC PROBLEMS AND EMERGENCIES ARISE?
1. HUMAN ERROR!
Can you spot the problem?
HUMAN ERROR

FAILURE TO OBTAIN AN ADEQUATE
HISTORY OR PHYSICAL
EXAMINATION ON THE PATIENT.
*Ideally, every patient scheduled for
anesthesia should have a complete physical
examination, and a thorough history should
be obtained with the owner present.

Less than ideal circumstances are
common:


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
Owner drops patient off in a hurry
Patient brought in by neighbor or friend
Receptionist takes the history
Physical exam is cursory or omitted
HISTORY?
PHYSICAL?
HUMAN ERROR

LACK OF FAMILIARITY WITH THE
ANESTHETIC MACHINE OR DRUGS
USED
The not so confident kennel worker who was
asked to assist in surgery today.
The confident, knowledgeable, experienced
RVT!
HUMAN ERROR

INCORRECT ADMINISTRATION OF DRUGS



INACCURATE WEIGHT
MATHEMATICAL ERRORS
USE OF WRONG MEDICATION
*Be aware of medications that come in different
concentrations

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ADMINISTRATION OF MEDS BY INCORRECT ROUTE
*knowledge of pharmacology
*drugs with narrow margin of safety
CONFUSION BETWEEN SYRINGES
*ALWAYS LABEL SYRINGES
USE OF INAPPROPRIATE SYRINGE SIZE
Propofol? IV IM or Sub Q
HUMAN ERROR

PRESSURES AND
DISTRACTIONS

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Feeling hurried or rushed
Distraction because of ineffective multitasking
Fatigue
Inattentiveness
 Be proactive, rather than reactive!
 Recognize early signs of trouble
 Pay attention to patient and machines
WHY,WHY,WHY
DO ANESTHETIC PROBLEMS AND EMERGENCIES ARISE?
2.
EQUIPMENT
FAILURE
*In many
cases the failure of
the machine is in
fact a failure of the
operator.
EQUIPMENT FAILURE

CO2 ABSORBER EXHAUSTION
*In re-breathing systems, if CO2 is not
removed from the circuit, the patient
will experience hypercapnia.
* In a non re-breathing system, if the gas flow
is too low, there may also be a significant rebreathing of expired gases.
↑ CO2 = Tachypnea, tachycardia, brick
red mucous membranes, cardiac
arrhythmias, respiratory acidosis
Human error!
EQUIPMENT FAILURE

INSUFFICIENT O2 FLOW
You will need to check both the flowmeter and
the oxygen tank pressure gauge.
Oxygen tank runs out or leak
 Hose becomes disconnected
 Obstruction or leak occurs
 Knob can become stripped, check bobbin tract
*If the oxygen flow stops while the patient is hooked
up to a non re-breathing system, the anesthetist
should disconnect the hose from the Endotracheal
tube, allowing the patient to breathe room air.
• If a re-breathing (circle) system is being used, the
patient can remain connected for a short period of
time, provided the reservoir bag remains inflated.

Human Error
EQUIPMENT FAILURE

ANESTHETIC MACHINE
MISASSEMBLED
Take time to learn and follow the
direction and path of gas flow within
the machine. Every time a connection
is added or removed, the anesthetist
should ensure that the correct pattern
of flow is maintained and that all
connections are secure.
**Soda-Lyme container main leak
EQUIPMENT FAILURE

ENDOTRACHEAL TUBE PROBLEMS

BLOCKED TUBES




Twisting or kinking of the tube (inappropriate
positioning)
Accumulation of material such as blood, saliva,
excess lubricant
Tube advanced too far into a bronchus
CHECK TUBE FUNCTION:


BAG the patient – watch for chest rising
Disconnect the patient – feel for air coming out of
the tube when the patient’s chest is compressed
If an accumulation of material is causing the obstruction, it
may be helpful to suction with a syringe through a redrubber catheter or feeding tube.
EQUIPMENT FAILURE

VAPORIZER PROBLEMS

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Wrong anesthetic in the vaporizer
Vaporizer is empty
Do not tip the vaporizer – could result
in leakage into the oxygen bypass
Vaporizer dial may be jammed
Don’t overfill the vaporizer
EQUIPMENT FAILURE

POP-OFF VALVE PROBLEMS

The pop-off valve is inadvertently left closed
Closed pop-off valve →pressure rises in the
circuit →reservoir bag expands, as well as the
patient’s lungs →exhalation is prevented
*This can lead to decreased cardiac output, low blood
pressure, and death.

If pressure rises in the circuit and
the bag is full and tight, the
anesthetist should attempt to open
the pop-off valve and/or decrease
the oxygen flow rate.
WHY,WHY,WHY
DO ANESTHETIC PROBLEMS AND EMERGENCIES ARISE?
3. ANESTHETIC AGENTS
Every injectable or inhalation agent has
the potential to harm a patient and, in
some cases, cause death. Review the
description of the pharmacologic and
physiologic effects of pre-anesthetic and
general anesthetic agents in chapters 1
and 3.
WHY,WHY,WHY
DO ANESTHETIC PROBLEMS AND EMERGENCIES ARISE?
4. PATIENT FACTORS
PATIENT FACTORS


GERIATRIC PATIENTS
(75% of life expectancy)
 POTENTIAL PROBLEMS
 Reduced organ function- liver, kidney, heart
 Poor response to stress
 At risk for degenerative disorders- diabetes,
CHF, cancer
 Increased risk for hypothermia and
overhydration
 Prolonged recovery
Geriatric Patients solutions

POTENTIAL SOLUTIONS
 Reduce anesthetic dosages
 Increase preanesthetic blood work
from mini to a general profile, include
u/a, x-rays, ECG if needed
 Allow a longer time for response to
drugs
 Reduce fluid rate
 Keep patient warm
 Choose anesthetic agents with
minimal CV effects
 Pre-oxygenate
PATIENT FACTORS


PEDIATRIC PATIENTS
(<3 months)
 POTENTIAL PROBLEMS

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Increased risk for hypothermia and overhydration
Increased risk of hypoglycemia, hypotension, Bradycardia
Inefficient excretion of drugs-reduced kidney and liver
function
Difficult intubation
Difficult IV cath placement
POTENTIAL SOLUTIONS

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Be proactive about heat preservation
Avoid prolonged fasting (+/- 5% dextrose
administration)
Reduce anesthetic dosages
Use a gram scale to weigh
Use inhalant anesthetics
PATIENT FACTORS

BRACHYCEPHALIC DOGS

POTENTIAL PROBLEMS
 Conformational tendency toward airway
obstruction

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Abnormally high vagal tone

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Elongated soft palate
Small nasal openings
Hypoplastic trachea
Difficult to intubate
Bradycardia
POTENTIAL SOLUTIONS
 Use an anticholinergic
 Pre-oxygenate
 Induce rapidly with IV agents
 Delay extubation
 Close monitoring during recovery- recover in a
excitement free area
PATIENT FACTORS

SIGHTHOUNDS

POTENTIAL PROBLEMS
 Increased sensitivity to barbiturates


Lack of body fat for
redistribution/elimination
of the drug
POTENTIAL SOLUTIONS
 Use alternative agents
PATIENT FACTORS

OBESE PATIENTS


POTENTIAL PROBLEMS
 Accurate dosing is difficult- lower dose /kg
 Poor distribution of drugs
 Respiratory difficulty- shallow rapid
respirations during anesthesia
POTENTIAL SOLUTIONS
 Dose according to ideal weight
 Pre-oxygenate
 Induce rapidly
 Delay extubation
 Close monitoring during recovery
PATIENT FACTORS

CESAREAN PATIENTS- normally an emergency
 POTENTIAL PROBLEMS
 DAM: increased workload to heart
 Respiration compromised
 Increased risk of hemorrhage- shock/hypotension
 Increased risk of vomiting/regurgitation- not
normally fasted
 Hypoxemia
 Hypercarbia
 Acid/base imbalance
 Tissue trauma
 Cardiac arrhythmias

OFFSPRING: susceptibility to the effects of the
anesthetic agents (reduced Cardio and Respiratory
function)
Cesarean patients

POTENTIAL SOLUTIONS
 DAM: IV fluids
 Clip patient before induction, in
lateral recumbency
 Pre-oxygenate
 Reduce anesthetic dosages
 OFFSPRING: use doxapram and/or
atropine
aspirate fluids from mouth
 Administer oxygen via face mask,
intubate with 18 or 16g IVC
 Keep warm
 Encourage nursing
Patient Factors

TRAUMA PATIENTS

POTENTIAL PROBLEMS
Respiratory distress commondecrease in tidal volume, increase in
CO2
 Cardiac arrhythmias
 Shock and hemorrhage- hypotension
 Internal injuries


POTENTIAL SOLUTIONS
Stabilize patient if possible
 Obtain chest rads, ECG
 Check for other concurrent injuries

Anesthetic Problems and
Emergencies: Patient Factors

Change in blood pressure
 Resulting from a change in cardiac output or
vascular tone
 Anesthetic depth will affect both parameters
 Hypotension → decreased tissue perfusion →
tissue hypoxia/anoxia → anaerobic glycolysis →
lactic acid production → acid/base imbalance
 Monitor blood pressure closely
 Doppler or oscillometric methods
 Digital pulse palpation
 Capillary refill time
TREATMENT OF HYPOTENSION
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REDUCE ANESTHETIC DEPTH
PRESERVE WARMTH
FLUID THERAPY- SHOCK RATE
ADMINISTRATION OF EMERGENCY
DRUGS:

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Corticosteroids
Sodium bicarbonate
Cardiac inotropes (dopamine,
dobutamine, ephedrine)
Fluid Therapy for Hypotension

Crystalloid fluid administration

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May have to deliver small boluses for
rapid therapy
Crystalloid fluids stay in intravascular
space
<2 hours
Watch for fluid overload, especially in
cats
Monitor heart rate, blood pressure,
mucous membrane color, and capillary
refill time
Fluid Therapy for Hypotension
(Cont’d)

Colloid fluid administration
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Helpful if blood pressure can’t be
maintained
Remain in the intravascular space longer
than crystalloids
Will increase colloidal osmotic pressure
and help stabilize blood pressure
Given in smaller volume in conjunction
with crystalloids
Hetastarch, Dextran 40 or 70, 10%
Pentastarch, plasma, whole blood

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Respiratory problems in the trauma patient
 Direct trauma to the chest leading to
lung collapse or failure of alveolar gas
exchange
 Must remove air/fluid from chest cavity
prior to anesthesia
 Deliver supplemental oxygen
Oxygen delivery methods
 Flow-by-oxygen
 Nasal catheters
 Oxygen collars
Thoracocentesis (Chest Tap)


To relieve pneumothorax or pleural effusion from
chest cavity
Performed by veterinarian Prepped by veterinary
technician
 Temporary bandage over chest wound
 Place animal in sternal recumbency or standing
position
 Shave lateral chest wall between the 7th and 9th
intercostal spaces caudal to point of the elbow
 Aseptically prepare 4 cm × 4 cm area
 Prepare a 20- to 22-gauge, 1- to 1½-inch
catheter with a three-way stopcock and large
syringe
 video
PATIENT FACTORS

CARDIOVASCULAR DISEASE

POTENTIAL PROBLEMS
Circulation compromised
 Pulmonary edema common
 Increased tendency to develop arrhythmias
and tachycardia


POTENTIAL SOLUTIONS
Alleviate pulmonary edema (diuretics)
 Pre-oxygenate
 Avoid agents that may cause arrhythmias
 Prevent overhydration- cut fluids in 1/2
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Preexisting cardiovascular disease
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Anemia
Shock
Cardiomyopathy (primary or
secondary)
Congestive heart disease (mitral valve
insufficiency)
Heartworm disease
Coexisting imbalances (e.g., hypoxia,
hypercapnia, electrolyte imbalances)

Bradycardia

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Most common cardiac anesthetic
problem
Caused by preanesthetic or anesthetic
drugs
Force of cardiac contraction may also
be decreased
Blood return to the heart may be
decreased (preload)
Treat with drugs or adjustment of
anesthetic depth

Cardiac arrhythmias

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Caused by anoxia/hypercarbia, poor
tissue perfusion, acid/base imbalance,
myocardial damage
Difficult to detect on physical
examination; may find dropped beats
Diagnose with ECG and report
immediately to veterinarian who will
determine the treatment required
Concurrent pulmonary disease is
sometimes seen
PATIENT FACTORS

RESPIRATORY DISEASE


POTENTIAL PROBLEMS
 Poor oxygenation of tissues
 Patient may be anxious and difficult to
restrain
 Increased risk of respiratory arrest
POTENTIAL SOLUTIONS
 Avoid unnecessary handling
 Pre-oxygenate
 Induce with injectable agents
 Intubate rapidly; control ventilation
 Monitory closely during recovery

Respiratory disease

Caused by:
Pleural effusion
Pneumothorax
Tracheal collapse

Clinical signs
Tachypnea
 Dyspnea
 Cyanosis

Diaphragmatic hernia
Pneumonia
Pulmonary edema

Anesthetic considerations
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VT is reduced and respiratory rate is
decreased in most anesthetized animals
A decrease in VT will result in a decreased
alveolar gas exchange
Lighten anesthesia as much as possible in a
patient with respiratory disease
Provide intermittent ventilation
Evaluate oxygen-carrying capacity with PCV
or pulse oximeter
Preoxygenation is necessary prior to
induction
Respiratory Volumes

Tidal volume-

Inspiratory Reserve Volume

Expiratory Reserve Volume

Residual volume

Minute Volume
Respiratory Capacities
(involve 2 or more pulmonary volumes)

Inspiratory Capacity

Functional Residual Capacity

Vital Capacity

Total Lung Capacity
Diaphragmatic Hernia

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Dysnpnea- pre oxygenate
Avoid head down positions
Intubate rapidly
“bagging” patient
Pay close attention to pulse ox,
capnograph, and do a arterial blood
gas if available.
PATIENT FACTORS

HEPATIC DISEASE
POTENTIAL PROBLEMS
 Liver necessary for drug metabolism, blood clotting factors,
plasma proteins, carbohydrate metabolism
 Decreased synthesis of clotting factors
 Possibly hypoproteinemic
 Dehydration common
 Anemic and/or icteric
 Prolonged recovery
 POTENTIAL SOLUTIONS
 Pre-anesthetic blood work
 Preanesthetic agents must be chosen with care
 Use inhalant anesthetics
Close monitoring during recovery
 Preanesthetic agents must be chosen with care


PATIENT FACTORS

RENAL DISEASE

POTENTIAL PROBLEMS
Delayed excretion of anesthetic agents
 Electrolyte imbalances common
 Dehydration may be present


POTENTIAL SOLUTIONS
Pre-anesthetic blood work
 Rehydrate before surgery
 Reduce anesthetic dosages
 IV fluids
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Renal disease

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Kidneys maintain volume and electrolyte
composition of body fluids
Renal excretion removes anesthetic
agents and metabolites from the body
General anesthesia is associated with
decreased blood flow to the kidneys
Diagnosis: urine specific gravity, BUN,
creatinine
Offer water up to 1 hour prior to
premedication
Correct dehydration prior to anesthesia
Anesthetic Problems and Emergencies:
Patient Factors (Cont’d)

Urinary blockage

Clinical signs
Depression
 Dehydration
 Uremia
 Acidosis
 Hyperkalemia (can lead to cardiac arrest)


Inhalation agents are less hazardous
for the patient
How to fix it…
Low heart rate- access depth- BP, jaw
tone, opiods.
Fix- decrease anesthetic , consider
anticholincergic

Increased heart rate- same checks as
above
Fix – turn up gas
But…. Low BP- HR increases as
compensatory stage – decrease gas
Lost ECG or sudden abnormal
reading



Check patients vitals manually
Check lead attachment, apply more
alcohol
IF you cannot hear heart rate, tell
DR.!
Low EtCO2

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
Check pulse and BP- precursor to
cardiac arrest
If normal BP and pulse: check O2 flow
rate
If BP is low- decrease anesthetic
High EtCO2- check trache tube, soda
lime
Then use ventilator, esp. in obese
patients

Low Blood Pressure



-
-
Low- check cuff size, and position- is it
on a joint?
Check with a doppler if oscillometic is
being used
Check anesthetic depth, decrease
vaporizer
Still low?
Try shock rate
Still low?
Alert vet and start colloids or what ever
Dr. prescribes.
High Blood Pressure

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Check cuff size and position
Check against doppler
Check anesthetic depth, and increase
gas
Consider drugs given, type of surgery,
or what surgeon is doing to patient at
that time
Cut fluids off
I smell gas
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Machine leak- sealed hoses
Trache tube leak
Inadequate machine scavenging
system
Exhausted F-air canister
Loose vaporizer cap
Vaporizer leak