Coping With Anesthetic Emergencies
Megan Brashear, BS, CVT, VTS (ECC)
DoveLewis Emergency Animal Hospital Portland, OR
Anesthesia can be a challenging time for the anesthetist. Depending on the procedure and the patient, your
time can go smoothly or it can be the roughest 90 minutes of your day. Preparation and thinking ahead can save
you stress later on and help you cope with anesthetic emergencies as they come up.
The first step to any anesthetic procedure is preparation. Even in emergency situations when the procedure
needs to happen immediately, do not skimp on preparation. Start with your equipment. Take the time to make
sure the correct anesthesia circuit is connected and that a leak test of the anesthesia machine has been
performed. To choose a circuit:
 Non-rebreather circuits should be chosen for patients <2kg or patients debilitated enough that they
cannot move the flutter valves of the anesthesia machine breathing through a pediatric circuit
 Pediatric circuit should be chosen for patients 2-7kg of lean body weight
 Adult circuit should be chosen for patients weighing >7kg of lean body weight
Make sure the reservoir bag is the proper size for the patient. The reservoir bag should hold at least 6 times the
tidal volume (10-15ml/kg) of the patient, so 60-90ml/kg. Always round up to choose the appropriate size. Check
the C02 granules. Check the gas anesthetic level. Make sure you have multiple sizes of ET tubes out and their
cuffs are checked for leaks.
It is also worth the time to make sure your patient is prepared. Obtain a full set of vital signs immediately before
anesthesia induction. Be aware of any complications that can/may occur during the procedure and discuss those
potential complications with your team. Know doses of emergency drugs and fluid bolus doses. Will you need
blood products? Will you need additional IV access? Thinking through potential problems and being prepared
for them will save you time when you need to be acting on these emergencies.
Checklists are mandatory in the human medical world and can also be used in the veterinary surgery suite.
While it may seem a little silly to run through a checklist on a puppy neuter, it is quite helpful to run that
checklist with the team prior to an emergency splenectomy. Take that time to discuss potential complications
and how the team wants to handle those. These checklists can also allow for a review of sterilization
procedures, the care of instruments, and any problems with equipment.
Anesthesia monitoring should be performed on every patient undergoing deep sedation or general anesthesia.
At least every 5 minutes full vital signs should be recorded, as well as observing the patient mucus membrane
color and CRT, checking reflexes, and palpating available pulses. The remainder of this lecture will cover
common causes of abnormal vital signs and options for determining cause and correcting problems while the
patient is under anesthesia.
Heart Rate
 Tachycardia: A higher than normal heart rate (>140 in dogs; >200 in cats) can be the result of a variety of
causes. The treatment for each cause will vary greatly, so it is important to quickly determine the cause
so the correct treatment is applied. Is your patient tachycardic due to improper anesthetic depth?
Surgical manipulation? Hypovolemia? Hyperthermia? Hypoxia? Anemia? Drugs administered? You will
need to quickly go through all of the potential causes for tachycardia and choose the correct treatment.
To do this, quickly check your equipment (ensure oxygen is flowing, the vaporizer is full and functioning,
the reservoir bag is not over filled), and then look at other vital signs. Remember that no vital sign

measurement is in a vacuum; always look at the big picture. How is the blood pressure? The Sp02? Look
at the patient – how well are they perfusing? What is their mucus membrane color and CRT? Talk to the
surgeon – how do things look in the abdomen? Are the surfaces dry and tacky? Is there more blood than
expected? If you can quickly determine the cause of the tachycardia you can correct it – with oxygen,
blood products, a crystalloid fluid bolus (10ml/kg), adding a colloid, increasing the inhaled anesthesia, or
administering pain medication. In many patients the problem can be corrected with a combination of
factors. Administering pain medication will allow you to lower the inhaled gas.
Bradycardia: A lower than normal heart rate (< 60bpm in dogs; < 100bpm in cats) can be the result of a
deep plane of anesthesia, disease process, or drugs administered. It is important not to treat just a
number, but to get the entire picture. How is the patient perfusing? Is their blood pressure maintaining?
Bradycardia can be addressed with anticholinergics (atropine, glycopyrrolate) and monitored closely
after those drugs have been administered. Atropine (faster onset, shorter acting) dose is 0.0050.01mg/kg in dogs and 0.02-0.04mg/kg in cats. Glycopyrrolate (slower onset, longer lasting) dose is
0.005-0.01mg/kg in dogs and cats.
ECG
Familiarize yourself with the common arrhythmias seen and how to treat them. If you are working with a patient
where the probability for arrhythmias is high, educate yourself on what they look like. VPCs and 2° AV Block are
the most commonly seen arrhythmias under anesthesia. Notate when the arrhythmia started, and watch the
patient’s heart rate, blood pressure, and perfusion status. Treatment may be necessary if the blood pressure or
perfusion status becomes abnormal.
Be sure to have drug dosages handy if they are needed. 2° AV Block, if it is caused by medications, can be
treated with atropine (if the patient has a pre-existing diagnosis of AV block then external pacing may be
required) VPCs, if the patient is clinical (blood pressure and perfusion abnormalities) are often treated with
Lidocaine (1-2mg/kg IV in dogs) first as a bolus and then as a CRI if the arrhythmia continues. VPCs can be
present for a number of reasons: trauma, pain, hypoxia, and reperfusion injury being the most common.
Splenectomy patients will often experience VPCs as well.
Respiratory
 Tachypnea: We will see tachypnea in patients mainly due to improper levels of anesthesia (too light),
hyperthermia, and hypoxia. Look at other vital signs (such as heart rate and blood pressure) to help you
determine the cause. In most cases you can correct tachypnea with a change in anesthetic depth or a
dose of pain medication.
 Bradypnea: This is often caused by anesthetic depth too deep, drugs given, patient status (obesity),
patient position, disease process, hypothermia, and severe hypotension. Some of these problems you
will have no control over, but thinking ahead to what you can do to alleviate some of the problem can
be helpful. Again, look at other vital signs and perfusion status when looking to correct this problem
before you make changes to anesthesia.
 Sp02: Pulse oximetry measures patient oxygenation. Hypoxemia is low oxygen content in arterial blood;
hypoxia is low oxygen in tissues due to poor perfusion. Both can cause changes in your Sp02 readings
and need to be addressed immediately. Sp02 measures the percentage of hemoglobin saturated with
oxygen and requires a certain level of perfusion to read in the periphery. If you are familiar with the
oxygen hemoglobin dissociation curve, you will see that a Sp02 in the low 90% range means a dramatic
drop in Pa02 readings, which means it is important not to let Sp02 readings drop below 95%. The probe
may need to be periodically moved to allow appropriate perfusion to the area. Check gum color,
respiratory rate, and heart rate to help interpret readings.

End Tidal C02: Carbon dioxide is the gas that drives respiration in our patients. It is a measurement of
patient ventilation and gives a more complete picture compared to using Sp02 alone. Drugs
administered, patient positioning, disease process and depth of anesthesia will all affect ETC02 reading.
ETC02 is also a measurement of perfusion and cellular metabolism. In order for carbon dioxide to travel
to the lungs to be exhaled and measured, appropriate perfusion and metabolism must happen. Changes
in ETC02 readings may be related to problems beyond the respiratory system; be sure to examine other
monitoring parameters when troubleshooting abnormalities.
o Hypercarbia/Hypercapnia: The result of hypoventilation (see bradypnea). If left untreated,
hypercarbia can cause central nervous system depression and eventually acidemia. If noted,
attempt to determine the cause and work to alleviate it while decreasing the patient’s ETC02.
This is accomplished by increasing the respiratory rate. A rapid, sudden drop in ETC02 can signal
impending arrest and should be viewed as an emergency that requires immediate attention.
o Hypocarbia/Hypocapnia: The result of hyperventilation (see tachypnea). Hypocarbia can cause a
respiratory alkalosis in the patient and should be addressed while attempting to increase the
patient’s ETC02. This is accomplished by decreasing the respiratory rate.
Blood Pressure
 Hypertension: (Systolic >140mmHg, MAP > 110mmHg) usually a sign that anesthesia isn’t deep enough,
hypertension can be treated by increasing inhaled gas or providing more analgesia. It is important to
think about your patient and whether or not they have a disease process that can be causing
hypertension. Increased intracranial pressure (especially in trauma patients), chronic renal failure and
metabolic diseases can cause hypertension.
 Hypotension: (Systolic < 80mmHg, MAP <60mmHg) low blood pressure is a common occurrence in
anesthesia, as many of the drugs used to induce and maintain anesthesia will cause hypotension. Also,
hypothermia can contribute to low blood pressure and is common in small animals under anesthesia.
Get the in the habit of looking at blood pressure and heart rate together, as the heart rate will give you
clues as to why the blood pressure is abnormal. You must determine the cause of the hypotension and
quickly work to improve perfusion (look for decreased CO, vasodilation, hypovolemia, hypothermia, or
too deep under anesthesia) as the patient can suffer long term effects of prolonged hypotension.
Appropriate pain management is important to allow for reduced gas anesthesia. The ability to increase
or decrease a CRI can allow for fine tuning of inhaled anesthesia and better blood pressure readings.
Fluids can be used to improve blood pressure, starting with a 10ml/kg crystalloid fluid challenge.
Colloids can be administered (5ml/kg bolus, not to exceed 20ml/kg/day) to maintain appropriate blood
pressure as well as blood products as needed. If the patient fails a fluid challenge, inotropes and drugs
to cause vasoconstriction can be utilized to maintain blood pressure and organ perfusion.
Temperature
 Hyperthermia is uncommon under anesthesia but can exist due to infection, inflammation, and drugs
given. Opioid administration in cats can cause dramatic (but transient) increases in body temperature.
Malignant hyperthermia is a rare genetic disorder that causes muscle tremors and dangerously high
temperatures. Hyperthermia can increase heart rate and cause vasodilation and hypovolemia if it goes
untreated.
 Hypothermia is probably the most common complication encountered with general anesthesia.
Hypothermia can decrease the inhaled anesthetic needs of the patient; this should be top of mind in
longer procedures where the patient continues to get colder. Hypothermia can also cause ECG
abnormalities, decrease coagulation, inhibit platelet function, and eventually can be the cause of death.
Upon recovery, hypothermia can prolong the process and cause shivering which will increase the
metabolic oxygen needs. Prevention is the best medicine for hypothermia and should remain on the list
for the cause of intraoperative anesthetic complications. Wrapping feet in bubble wrap, warming the
chest and head of the patient (assuming the surgery is abdominal), using warm abdominal lavage, and
warming the IV fluids are all methods for warming or keeping patients warm. One of the more effective
ways to accomplish this is to warm the inhaled air of the patient. Fresh oxygen is ice cold; by placing a
warm water bottle over the anesthesia circuit can be helpful.
Arrest
Cardiopulmonary arrest can happen in anesthetized patients for a number of reasons. In many patients
respiratory arrest will happen first, but if it goes unchecked cardiac arrest will soon follow. As the anesthetist,
hopefully you will note any warning signs of arrest (change in respiratory rate/depth, sudden change in heart
rate, pale/gray mm color, drop in blood pressure, drop in ETC02) and start to make changes prior to arrest. If
your patient does arrest on the anesthesia table:
 Turn off any inhaled anesthesia and any opioid CRI medications
 Reverse any opioid medications using naloxone (0.01-0.04mg/kg IV)
 Ventilate the patient at 10bpm – inhale for one second then exhale
 Begin compressions – often the surgeon can cut through the diaphragm and begin internal cardiac
massage – at 100bpm
 Administer drugs as needed (epinephrine 0.01mg/kg IV; atropine 0.05mg/kg IV)
An emergency is defined as a serious, unexpected, occurrence requiring immediate action. As anesthetists, the
best we can do is to remove the ‘unexpected’ from the definition. Think through the patient history, the disease
process, and the procedure to determine the risks to the patient. Plan your response to potential emergencies
by placing an additional IV catheter, having a unit of blood on hand, and knowing how to do a CRI calculation.
There is no substitute for preparation and critical thinking, and with knowledge and planning comes successful
anesthesia.
References:
Bryant, Susan. Anesthesia for Veterinary Technicians. Ames, IA: Wiley-Blackwell, 2010. Print.
McKelvey, Diane, K. Wayne. Hollingshead, and Diane McKelvey. Small Animal Anesthesia & Analgesia. St. Louis:
Mosby, 2000. Print.
Seymour, Chris, and Tanya Duke-Novakovski. BSAVA Manual of Canine and Feline Anaesthesia and Analgesia.
Gloucester, England: British Small Animal Veterinary Association, 2007. Print.
Silverstein, Deborah C., and Kate Hopper. Small Animal Critical Care Medicine. St. Louis, MO: Saunders/Elsevier,
2009. Print.