Anaesthesia for Airway, Dental and Ocular Surgery Flashcards
what are the main concerns with dental surgery?
access to face and mouth limited - difficult to check depth
patients commonly geriatric with underlying conditions
lots of water - aspiration risk, can become very cold
often final procedure of day when staff are tired
dentistry can be very painful
what are the anaesthetic considerations for dental surgery?
pain
haemorrhage
hypothermia
aspiration of water/fluids
length of procedure
concurrent diseases
why is it difficult to assess blood loss during dentals?
usually mixed with water - looks like more than it is
what are the the anaesthetic concerns for geriatric patients undergoing dental surgery?
reduced CV reserve
reduced FRC
reduced muscle mass, increased fat tissue
prone to hypothermia
may have reduced kidney +/- liver function
what does it mean if a patient has reduced CV reserve?
baroreceptor function may be reduced - more prone to hypotension
what does it mean if a patient has reduced FRC?
more prone to hypoxia
what should we consider in older patients which might have reduced liver/kidney function?
consider drug dosages - may have less or exacerbated effects/length of action
what pre-op considerations might we have for patients undergoing dental surgery?
full clinical exam
blood/urine testing
consider other disease processes
anorexic? (common in cats with dental disease)
any other diagnostic testing (U/S, x-ray, ECG)
what can we use for MAC sparing in dental procedures?
adequate analgesia
local blocks
what are our airway considerations when anaesthetising a patient for a dental procedure?
cuffed ET tube essential
mouth pack to avoid AP
care when turning patient - check for fluid in mouth
observe tube to ensure not kinking or twisting
what are the perioperative considerations for dental procedures?
protect airway - cuffed ETT, throat pack
long procedure - consider patient temperature, drug top-ups if req
look after the eyes (patient and staff)
haemorrhage
consider patient positioning
how can we make patients more comfortable during/after dental procedures
pad joints to avoid sores
consider effects of atelectasis
tube care when moving
what is the advantage of local blocks for dental procedures?
dentals are painful - blocks will reduce maintenance anaesthetic requirements
improve post-op pain management
may improve speed of recovery (eating)
what are the 4 main dental nerve blocks?
rostral maxillary (infraorbital)
caudal maxillary
caudal mandibular
mental
what does the infraorbital nerve block affect?
soft tissues, incisors, canines and premolar teeth
where is the infraorbital foramen located?
(in dogs) located on maxilla, dorsal to the third maxillary premolar
why should care be taken performing an infraorbital nerve block in cats/brachy dogs?
the foramen is located at the level of the medial canthus of the eye (needle could penetrate eyeball)
what does the caudal maxillary nerve block affect?
all bones of the maxilla
soft and hard palates
soft tissues of the nose, upper lip and dentition rostral to the maxillary second molar
where is the caudal maxillary foramen located?
just caudal and central to the last maxillary molar
what does the mandibular nerve block affect?
entire hemimandible teeth of the lower jaw
where is the mandibular foramen located?
needle inserted percutaneously at the ventral angle of the mandible
why are bilateral mandibular nerve blocks discouraged?
due to risk of damage due to lack of sensation in the recovery period
what type of nerve block should not be administered bilaterally?
bilateral mandibular block
what does the mental nerve block affect?
lower incisors, skin and tissues rostral to the foramen
where is the mental foramen located?
ventral to the rostral root of the second premolars
why is the mental nerve block not often carried out in small animals?
can be tough to locate the foramen
which block may be preferred over the mental block in small animals?
mandibular
what equipment should be prepared for local block placement?
sterile needle and syringe
local agent
scrub
alcohol wipe
method of recording doses/times
(sterile gloves)
what should be considered when administering local blocks to cats?
intubeaze - 2.27mg lidocaine per spray
what are the post-op considerations for dental procedures?
re-assess/pain score for analgesia
remove mouth pack/gag
dry off as much as possible for temperature maintenance
tempt to eat
continue fluids if necessary
thorough discharge advice for owners - expect bleeding
why might an animal have ocular surgery?
cataract sx, enucleation, eyelid mass removal, entropion, cherry eye, trauma
what are important pre-anaesthetic considerations for ocular surgery?
is the animal experiencing pain
could the eye rupture
are there any underlying diseases e.g. diabetes
are they on any medication
what procedure is being performed
what should be ascertained before ocular surgery?
full clinical exam and hx
pre-op screening if indicated
what should not be used for preparation for ocular surgery?
hibiscrub
what are the specific peri-operative considerations for ocular surgery?
preventing further trauma to eye, preserving sight
maintenance of central eye for intraocular procedures
adequate analgesia
what is the normal intraocular pressure?
15-20mmHg
what determines intraocular pressure?
a balance of aqueous humour production and absorption
other factors e.g. pupil size, corneoscleral rigidity, extra ocular muscle tone, vascularity of the globe
why do we want to avoid acute increases in intra-ocular pressure?
to avoid damage to the eye
how can we manage intraocular pressure during surgery?
maintain a normal Co2
avoid coughing on intubation/extubation
avoid drugs with emetic effects (e.g. morphine)
be aware of effects of drugs on IOP and use drugs judiciously
avoid neck restraint/jugular pressure
positioning - avoid head down position
what is the oculo-cardiac reflex?
sudden reduction in heart rate associated with traction on the eye or surrounding structures
why does the oculo-cardiac reflex occur?
due to stimulation of the trigeminal and vagal nerves
how should the oculo-cardiac reflex be managed?
surgical manipulation should stop and manage by administration of anticholinergics
how can you maintain a central eye during ocular surgery?
most common is use of a NMBA
why is it essential for all ocular surgery patients to wear a bustEr collar?
to avoid scratching eye/rubbing face along surfaces for contact
which block might be used to provide analgesia during ocular surgery?
retrobulbar
what does a retrobulbar block affect?
cranial nerves II III IV V and VI
what are the important considerations post-op for ocular surgery?
analgesia - pre-emptive and multimodal
buster collar - avoid mutilation
fluid therapy if needed
patient warming
feed, give opportunity to defecate
prevent vomiting/coughing post-op especially if IOP increased
consider sedation if anxious/fractious
what is important to avoid after ocular surgery?
coughing/vomiting especially if IOP increased
what are the primary abnormalities in BOAS patients?
stenotic nares
aberrant nasal turbinates
elongated/thickened soft palate
tracheal hypoplasia
what is primary BOAS?
where it is identified early on and present before significant clinical signs
what is secondary BOAS?
develops as a consequence of longstanding increase in respiratory pressures
how does boas cause secondary respiratory/digestive issues?
animal has to pull harder on inspiration, creating negative pressure in the throat/neck/chest
what are the secondary abnormalities of BOAS?
laryngeal collapse
eversion of laryngeal saccules
GI - reflux, regurgitation
why is IV access important in BOAS cases?
can rapidly proceed to induction of anaesthesia and intubation for prompt airway security
why is it important to prevent stress in BOAS cases?
to prevent raising temperature, causing panting and GI signs
why might we sedate a BOAS patient before placing an IV catheter?
if catheter placement is causing undue stress
why must sedated bOAS patients be observed closely?
can easily obstruct and regurgitate
why might we use sevo over iso for BOAS maintenance?
faster recovery of laryngeal reflexes
what might be the disadvantage of using sevo for BOAS patients?
quicker recovery may increase chance of dysphoria/anxiety/stress
what drugs are commonly used for premed for airway surgery?
ACP/A2 agonist combined with an opioid
acp will provide longer sedation than an a2 agonist
how can we protect the airway in patients undergoing airway surgery?
pre-oxygenate
intubation stylet may be helpful
large range of ETT sizes - always cuff
always have suction available
head down until airway secured
what are the perioperative considerations during BOAS surgery?
airway management vital, may require ventilation support
careful and close monitoring, watch ventilation
maintain heat but avoid overheating
eye care is crucial
what are the post-op considerations for BOAS surgery?
observe closely - don’t remove ETT until swallowing and can maintain patent airway
mild sedation can be useful if patient agitated
ware with warming techniques
oxygen supplementation (+pulse ox if tolerated)
early discharge if stress + safe to do so
what should we always be prepared for when recovering a BOAS patient?
re-intubation
why might NSAIDs be avoided intra-op in BOAS patients?
in case steroids required for post-op obstruction
how does laryngeal paralysis often present?
stridor
exercise intolerance
panting
coughing, hoarse bark
what is stridor?
abnormal, harsh high-pitched sound during inspiration/expiration resulting from airflow through an obstructed airway
what is stertor?
noisy breathing sound - like snoring
low pitched
what are the non-surgical approaches to laryngeal paralysis?
weight loss
exercise restriction
owner education
what is the surgical approach to laryngeal paralysis?
laryngeal tie-back
how can a nurse help with a patient who presents with laryngeal paralysis?
put in quiet/stress free environment
use a fan - cool and blow air into airways
oxygen supplementation if not stressful
start recording esp RR
leave alone until calm (with observation)
enquire with vet about butorphanol
what is laryngeal tie back surgery called?
unilateral arytenoid lateralisation
why do animals with laryngeal paralysis present with dyspnoea?
due to closure of the vocal cords
why should we assess the larynx under a light plane of anaesthesia?
anaesthetics affect mobility of the larynx
what are the pre-operative considerations for laryngeal tie-back surgery?
pre-oxygenate
reduce stress
anti-tussive drugs
light plane of anaesthesia so that VS can assess larygngeal function
pain management
what should be involved in post-op care after laryngeal tie-back surgery?
very close observation - AP high risk
assess pain
avoid things around neck
wet food made into balls, elevated feeding and water
avoid excitement - consider sedation if req
what are some of the presentations requiring bronchoscopy?
variable - chronic cough, suspected lung infection, feline asthma, airway parasites, chronic aspiration pneumonia, neoplasia
are patients requiring bronchoscopy likely to saturate well on room air?
no
what can be given to bronchoscopy patient as a bronchodilator?
terbutaline
why should care be taken when giving terbutaline as a bronchoconstrictor?
CV side effects - tachycardia
when might terbutaline be given?
may be given as a bronchodilator to bronchoscopy patients
why is bronchoscopy usually performed?
for sample collection (bronchial alveolar lavage)
what are the pre-op considerations for bronchoscopy?
history and clinical exam, assess degree of respiratory compromise
rule out cardiac disease
further testing, blood tests depending on px
BGA, x-rays
what may be required for stabilisation pre-bronchoscopy?
O2 supplementation and sedation if required
inhaled bronchodilators e.g. terbutaline
systemic steroid and anti-tussive meds
what is the issue with the ET tube during bronchoscopy?
may not be able to maintain it in place - some larger tubes can fit scope inside
what are the temperature considerations during bronchoscopy?
patient easily cold - coupage, usually uncovered
which drug might be useful for bronchoscopy? why?
ketamine and propofol - have bronchodilatory effects
what are the airway management options for bronchoscopy?
large diameter ET tube - pass scope through
small diameter tube - extubate and use TIVA
SGAD/LMA
what is the most important piece of monitoring equipment during a bronchscopy?
pulse ox
why is it sensible to consider TIVA for bronschoscopy?
easier access to required areas
avoids leakage of inhalant agent into surrounding air
what are the potential peri-operative issues during bronchoscopy?
hypoxia
bronchoconstriction (esp after BAL)
desaturation and shark fin capnograph (obstructive)
reduced compliance
laryngeal oedema (cats)
airway/lung rupture - possible during FO removal or biopsy
what equipment should we get ready for a bronchoscope?
endoscope
sterile saline
collection pots
mouth gag?
urinary catheter (if blind BAL)
syringes
emergency box/induction agent
why is it valuable to take a pre-scope sample of the endoscope?
to ensure any abnormalities found (e.g. fungus) were not present in the scope before it was introduced to the patient
why does bronchoscopy often require multiple people?
needs to be fast
coupage required as well as close monitoring of the patient
things can go wrong quickly
need quick access to emergency drugs/oxygen
why should the patient be monitored closely in the recovery period from bronchoscopy?
risky period - can easily occlude
may have cough
how can we lower risk of occlusion after bronchoscopy?
keep head elevated, use towels
monitor closely
how can we monitor/support the patient after bronchoscopy?
constant observation until fully recovered
use pulse ox until no longer tolerated
supplement oxygen
why should bronchoscopy patients be monitored regularly after the procedure?
tension pneumothorax can manifest clinically later in the recovery period
what are the potential post-op complications after bronchoscopy?
haemorrhage in the airways
desaturation of oxygen
pneumothorax due to damaged bronchi (poss tension pneumothorax)
when might pharyngostomy intubation be performed?
avoids the oral cavity - for cases where orotracheal intubation is not possible
what are the overall main challenges for dental/ocular/airway surgery?
access to head/eyes is limited - depth, avoid breathing systems that require access near head
use appropriate monitoring, may have to attach pulse ox elsewhere
close eye on capnography to ensure tube isn’t kinking
remember eye/mucous membrane lubrication
