Anaesthetic Emergency Flashcards
What can reduce the risk of an anaesthetic emergency?
- adequate pre-anaesthetic assessment
- appropriate use of anaesthetic drugs
- careful monitoring
What are the 4 general causes of an anaesthetic emergency?
- Human error - fatigue, distracted, incompetent
- Equipment failure - ET tube, gas, APL valve, circuit
- Anaesthetic agents - incorrect for patient e.g. ACP for a hypovolaemic patient
- Patient variation factors - underlying disease, breed risks, age… etc.
Why are neonates at more risk of anaesthetic emergency?
- don’t possess much plasma protein to bind drugs
- don’t have great ability in kidney and liver to metabolise and excrete the drugs.
Why are geriatric animals more at risk?
- more likely to have underlying disease
- reduced liver and kidney function so diminished ability to metabolise and excrete drugs
Why are brachycephalic breeds and obese patients more at risk?
May struggle to breathe
Why do thinner dogs such as sighthounds have more risk of an anaesthetic emergency?
- less body fat so affects the distribution of lipophilic anaesthetic drugs and can slow recovery
What is the first thing you need to do in ANY anaesthetic emergency
Alert the operating VS
What is Atropine used for in an emergency?
Used to treat cardiac arrest in conjunction with adrenaline
- reverses bradycardia by reducing vagal tone
What is Adrenaline/Epinephrine used for in an emergency?
Used to treat cardiac arrest - in conjunction with Atropine
- It increases heart rate and force of contraction
What is Frusemide used for in an emergency?
Used for cerebral or pulmonary oedema, congestive heart failure and oliguria
What is Lidocaine (w/o epinephrine) used for in an emergency?
It decreases the rate of contractions of the heart by blocking sodium channels.
Used to treat arrhythmias (should use an ECG)
What is Diazepam used for in an emergency?
Used to treat seizures
What is Naloxone used for in an emergency?
Opioid antagonist - used to reverse opioids if causing unwanted effects e.g. respiratory depression
What is Dopamine used for in an emergency?
Increases the force of myocardial contraction ( to maintain blood pressure)
What is Doxapram used for in an emergency?
Used to stimulate respiration in neonates.
An analeptic drug (respiratory and CNS stimulant)
What is Atipamezole used for in an emergency?
Its an alpha-2-adrenoreceptor antagonist
May be used to reverse or partially reverse the effects of medetomidine (which can cause respiratory depression, vasoconstriction etc)
What is Sodium bicarbonate used for in an emergency?
Used to treat severe metabolic acidosis or hyperkalaemia (often used in conjunction with CPR)
What signs would indicate that a patient is too light?
Patient movement
Tachycardia
Elevated BP
Muscle twitching in response to stimulation
Why could a patient be too light?
- Vaporiser problems - off, empty..
- ET tube problems - misplaced, blocked, too small, cuff not inflated
- Breath-holding - may be due to Propofol
- Shallow respiration
- Inadequate O2 flow
- Anaesthetic machine malfunction
What should you do if a patient is shallow breathing or breath-holding and therefore too light?
Give them a few breaths via IPPV to allow anaesthetic gas to reach the lungs
What are the signs that a patient is too deep?
- Slow, shallow respiration
- Pale/ cyanotic MMs
- CRT >2s
- Bradycardia with weak pulse
- Absence of reflexes
- Cold extremities
What can cause the patient to be too deep?
- Vaporiser set too high
2. Presence of pre-existing problems e.g. shock or anaemia
What should you do if the patient is too deep?
Tell VS
Turn down or Turn off the vaporiser!
Initiate IPPV if respiration is shallow
Supportive treatment - fluids, Reversal drugs
What does IPPV stand for?
Intermittent Positive Pressure Ventilation
Describe how you would administer IPPV
- Patient must be intubated and on an O2 supply
- Close (or partially lose for Bain and Ayres T) the APL valve
- Fill the reservoir bag with O2
- Gently squeeze the reservoir bag until the patients chest rises slightly
- Open the valve and allow the patient to expire (2-3 times the length of time it took to inhale)
- Repeat every 6 seconds until signs of recovery noted (approx. 10 times per minute)
What would the signs be in a patient that was too deep, receiving IPPV that it was working?
Increasing HR
Stronger pulse
Improved MM colour
Improved CRT
What are the 2 types of respiratory arrest?
- Temporary - Induction apnoea is quite common
2. True respiratory arrest - Requires attention - precursor to cardiac arrest!
Why does true respiratory arrest happen?
- anaesthetic overdose
- lack of oxygen - equipment
- Pre-existing respiratory disease
- side effects of pre-meds or induction agents
What do you do if a patient has induction apnoea?
Check first if they are holding their breath!
- Look at their eye position and palpebral reflex (if eyes are central and there is no PR then they are very deep!)
- Will need IPPV for a short time ( assess depth and decide if vaporiser should be on or off) if eyes central and no PR then switch off vaporiser!!
What are signs of true respiratory arrest?
- dyspnoea before arrest
- cyanosis
- abnormal HR, CRT, pulse , pupil dilation
What is the appropriate response to respiratory arrest?
- Tell VS
- place ET tube if not intubated. Give 100% o2
- Check heart to ensure no cardiac arrest
- Commence IPPV:
- Deliver one breathe every 6s until vital signs improve. Once vital signs are normal, cease IPPV for 30s to see if patient can breathe on own. If not, continue IPPV
- IV fluids and drugs may be administered
- Keep patient warm
What are the signs of cardiac arrest?
- No heartbeat can be auscultated, palpated or seen on ECG/ultrasound
- No arterial pulse can be palpated
- MMs grey or cyanotic
- Prolonged CRT
- Pupils widely dilated with no pupillary light reflex
- Respiration absent or Cheyne-Stokes respiration (indicated imminent death)
What can cause cardiac arrest?
Underlying CV disease (esp in cats)
Anaesthetic overdose
Other systemic disease
What is the appropriate response to cardiac arrest?
Inform Vs
- START COMPRESSIONS!
- Deliver compressions at 100-120bpm in 2m cycles
- Intubate patient if not already
- IPPV at 1 breath every 6s (assistant)
- If on own, deliver 30 cardiac compressions then 2 breaths*
- Check pulse after each 2 minute cycle and continue until spontaneous return of pulse and breathing
- VS may advise drug administration e.g. adrenaline and IV fluids
- Keep patient warm
- Can use defibrillator
After 15 minutes, outcome poor
Describe the technique for cardiac compressions
R lateral recumbency
Heel of hand at fifth intercostal space
Compress chest by 1/3-1/2 width of chest
- In small dogs and cats, use thumb and fingers to compress chest
What is a defibrillator used for?
Uses electricity to stimulate cardiac muscle contraction
What is an Ambu bag?
Self-inflating resuscitator bag - good if don’t have an o2 supply
What is a urinary catheter used for in arrest?
Used to administer drugs down the ET tube
