GI Endoscopy Flashcards
what does endoscopy mean?
to view within
what does viewing images during endoscopy rely on?
light source within the body cavity and the resulting image transferred to an eyepiece or monitor
what are the 2 main types of endoscope?
flexible
rigid
what are flexible endoscopes used for?
bronch
GI
what are rigid endoscopes used for?
rhino
cystoscopy in female patients
what are the 2 main roles of endoscopy?
diagnostic
theraputic
what are the diagnostic roles of endoscopy?
observation
sampling
what are the therapeutic uses of endoscopy?
FB retrieval
oesophageal / colonic stricture dilation
gastrotomy tube placement
what sampling may be performed via endoscopy?
fluid (e.g. BAL)
brush cytology
FNA
biopsies
what are the benefits of endoscopy?
minimally invasive
low morbidity / mortality
no convalescence
what is most endoscopy morbidity and mortality related to?
anaesthetic rather than scope itself
why may no convalescence be useful in endoscopy?
usually final investigation of CIE which can be treated with steroids
steroids cannot be started until healing has ended
why may endoscopic biopsies be better for patient welfare than surgical?
GA risk
surgery trauma
no convalescence so steroids can be given straight away as no healing required
what are the limitations of endoscopy?
cannot visualise the whole GIT
can assess morphology but not function
mucosal evaluation only
cannot evaluate extra GI disease
what other type of endoscopy may be performed instead of of traditional endoscopy to view the whole GI tract?
capsule endoscopy
how does capsule endoscopy work?
camera within a capsule is fed to patient and images taken as it moves through the GIT
what is the downside of capsule endoscopy?
no biopsies
how can the mucosa be evaluated in GI disease?
visual
histopathalogical
how is GI function assessed?
clinical signs
bloods
what are the known contraindications for endoscopy?
know GI surgical disease
inadequate investigations to rule out extra GI disease
patient unsuitable for anaesthesia
coagulopathy
inadequate patient prep
how can GI surgical diseases be ruled out before endoscopy?
imaging and bloods
what are examples of known GI surgical diseases?
perforation
mass lesion
what can make a patient unsuitable for anaesthesia?
inadequate cardio/pulmonary function
inadequate hepatic / renal function to manage drug clearence
who can gastric over distension affect?
endoscopist
anaesthetist
how does gastric over distension affect the endoscopist?
challenging pyloric intubation
increase in antro-pyloric motility
how does pyloric distension make pyloric intubation harder?
increases acuteness of angle between cardia and pylorus
how does gastric over distension affect the anaesthetist?
caudal vena cava compression
diaphragmatic splinting
how does compression of the caudal vena cave affect the patient?
reduction in venous return so reduced cardiac output and so reduced blood pressure
how does gastric over distension cause diaphragmatic splinting?
stomach prevents diaphragm from working fully and reduces compliance
what can diaphragmatic splinting lead to?
reduced tidal volume
what are the main complications seen in GI endoscopy?
gastric overdistension
acute bradycardia and AV block
aspiration
bacteraemia
GI perforation
haemorrhage
how can GI endoscopy cause acute bradycardia / AV block?
GI tract linked closely to vagus nerve
endoscopy may trigger vagal reflex leading to bradycardia and AV block
how vagally mediated bradycardia be treated?
atropine
glycopyrrolate
how can aspiration be prevented during endoscopy?
adequate cuff
aspirate pharynx and oesophagus as procedure ends to ensure patient is dry
when may bacteraemia occur?
transiently during colonoscopy
how can bacteraemia risk be managed?
prophylactic antibiotics if at risk
what patients may be at risk from bacteraemia during endoscopy?
those with a pacemaker
when does GI perforation usually occur during endoscopy?
pre-exisiting ulcer/severe pathology
what may suggest gastric rupture due to endoscopy?
abdominal swelling as gas from stomach enters abdominal cavity
what may haemorrhage arise from during endoscopy?
mucosa
laceration of major vessels
is mucosal haemorrhage following biopsy common?
no - unless coagulopathy
what procedures may cause haemorrhage due to laceration of major vessels during endoscopy?
FB removal (pressure necrosis or laceration from sharp FB)
stricture dilation
what are the main elements of the endoscopy system?
light source
air/water insufflator
suction pump
endoscope with insertion tube
forceps
what is the role of air/water insufflation within endoscopy?
inflation
aids viewing
what is the role of suction within endoscopy?
removal of air and fluid
sampling
increasing view
what light source is needed for endoscopy?
cold light
what light source is commonly used in endoscopy now?
xenon arc
what are the benefits of xenon arc lights for endoscopy?
bright
last up to 1000 hours
no colour alteration
what are other light options for endoscopy?
tungsten halogen (historically)
metal halide
LED
what is housed within the light source?
air pump for insufflation
separate suction pump for deflation
water reservoir for washing lens
what connects the endoscope to the power source?
light guide connector
what is the role of the endoscope insertion tube?
within patient
what are the controls found on the control body of the endoscope?
suction/flush
direction controls
how is light transmitted fibreoptically?
non-coherent via glass fibre optics
what is non-coherent light transmission?
light is bounced down the tube
how is the image transmitted during endoscopy?
fibre optics
video
how does fibre optic image transmission work?
individual glass fibre is coated in lower optical density glass cladding
image is viewed through total internal reflection via individual fibre bundles
what is the benefit of fibre optic bundles for image transmission?
image is viewable as is coherent
what can happen if individual fibreoptic bundles are not kept together?
image becomes scrambled and cannot be interpreted
how is image transmitted with video endoscopy?
not via fibre optics
via a wire from a video chip behind the lens
what is the name of the video chip found in video endoscopy?
CCD
what are the advantages of fibreoptic endoscopy?
portable
wide range of sizes
moderate cost
what are the disadvantages of fibre-optic endoscopes?
faceted ‘honeycomb’ image due to fibreoptic bundles
fragile
size of endoscope dictates image quality
what methods can images from fibreoptic scopes be viewed via?
eye piece
video via a camera adapter on eyepiece (think arthroscope)
is the usage of video and fibreoptic endoscopy the same?
mechanically identical
what type of illumination is used in video-endoscopy?
non-coherent
how is the image transmitted in video endoscopy?
CCD detects image which is transmitted to the screen
what are the advantages of video endoscopy?
more hygienic due to lack of eye piece
excellent image quality
image control buttons
what are the disadvantages of video endoscopy?
expensive
no portable
smallest diameter not possible as chip must be accommodated
what is the usual diameter of gastro- insertion tubes?
5.5-9.5mm
what is the usual diameter of colono- insertion tubes?
10-13mm
what is the usual length of gastric endoscopes?
1-1.5m
what does length of the scope often correlate with?
diameter
what are the different viewing angles seen in endoscopes?
end or side viewing
how can a scope be steered?
uniplaner (L and R)
multiplaner (up and down as well as L and R)
what channel is seen on endoscopes?
accessory/biopsy channel
what is retroflexion?
scopes ability to turn back on itself
why is retroflexion important in endoscopy?
visualise cardia
FB retrieval
entering duodenum
what must be used with caution if retroflexion is occurring?
instruments as diameter of biopsy channel is reduced through retroflexion
what does the size of the insertion tube dictate?
biopsy channel size and so accessories that can be used
what effect does the biopsy channel have on biopsy quality?
larger channel = high quality biopsies
what size should we aim for the biopsy channel to be?
2.2-2.8mm as minimum
what are the main biopsy accessories available?
cytology brush
sheathed needles
biopsy forceps
lavage (BAL) tubes
what types of biopsy forceps are available
elipsoid/ round
fenestrated/whole
with spike/no spike
swing jaw / fixed angle
alligator / smooth
rotatable / non-rotatable
what is the downside of swing jaw biopsy forceps?
lower quality biopsies
can biopsy forceps be reused?
yes if sterilised
what are the key factors which determine biopsy quality?
cup size and pressure applied to tissue
what size of biopsy forcep cup will improve biopsy quality?
bigger = better
how should biopsy forceps be held open?
fingers and thumb pushed apart
how should biopsy forceps be held closed?
fingers and thumb together (all times unless actively grabbing tissue)
what must be confirmed before endoscopy begins?
endoscopy is indicated
when is endoscopy indicated?
exclusion of extra-GI signs
exclusion of surgical disease (imaging)
contraindications considered
how long should patients be fasted before gastroscopy?
12 hours
what is the purpose of the 12 hour fast before gastroscopy?
empty stomach and duodenum
what is the benefit of an empty stomach / duodenum for endoscopy?
visualisation improved
maneuverability improved
food increases risk of aspiration and regurgitation
what impact can food in the stomach have on the scope equipment?
clogs channels
how long after barium studies should you wait before scoping?
24 hours at least
why must you wait 24 hours after barium studies to scope patients?
barium causes irreparable damage to scopes
what may be caused by some GI diseases that can impact visualisation?
delayed gastric emptying due to impaired motility
how long should patients be fasted for before colonoscopy?
24-48 hours (max)
what is involved in patient prep for colonoscopy?
oral lavage
multiple ‘high’ ememas
what is used for oral lavage?
polyethylene glycol solutions (Kleen Prep)
when should oral lavage be performed?
day before scope
how often should oral lavage be performed?
3 doses 2-4 hours apart
what volume of Klean Prep should be used for dogs?
25-30 ml/kg
what volume of Klean Prep should be used for cats?
20 ml/kg
how can oral lavage be administered?
attempt to give in chicken water
stomach tube
what tube type will be used in cats for oral lavage?
NO tube
what must be done if using stomach /NO tube for oral lavage?
ensure within stomach
check for reflux / coughing / distress
what are the risks associated with oral lavage?
tracheal intubation
aspiration
trauma
when is oral lavage contraindicated?
if significant pre-exisiting aspiration risks (e.g. BOAS, LP)
when should enemas be performed before colonoscopy?
1-2 hours
what is used for a pre-scope enema?
warm water
what should not be used for pre-scope enema?
phosphate
cleansers / laxatives
why must phosphate not be used for pre-scope enemas?
can cause hyperphosphataemia as phosphate is absorbed across colon wall
what can be used to perform an enema?
Higginson pump
enema bucket
tube and funnel
how much fluid should be used for an enema in dogs?
1L/30 kg
how much fluid should be used for an enema in cats?
20 ml/kg
when should enemas be stopped?
fluid runs clear
maximum volume reached
when are enemas more effective?
if performed on the awake patient so they can go to the toilet after
why may some people prefer opioids not to be given for endoscopy?
influence on sphincter tone - unlikely and more due to operator skill
what drug should be avoided in endoscopy?
atropine
why must atropine be avoided for endoscopy?
impact on GI motility
why is a smooth induction important for endoscopy?
prevention of aerophagia which will cause distension before the scope is even introduced
why is cuffing of the ET tube necessary?
reflux/regurge is a risk
why must nitrous oxide be avoided in endoscopy?
accumulates within gas filled organs
what are the specific endoscope considerations?
gastric dilation
reflux and aspiration on recovery
what position should patients be in for GI endoscopy?
left lateral
why is left lateral recumbancy preferred for GI endoscopy?
pylorus and descending colon will be airfilled and positioned dorsally making them easier to intubate
what might indicate positioning in right lateral recumbancy for GI endoscopy?
G tube placement for access
FB removal may require position changes
what is essential for all endoscope procedures to prevent scope damage?
mouth gag
what mouth gag should not be used in cats?
spring loaded - risk of nerve damage and blindness
where should the ET tube be secured?
mandible or maxilla
why is it important that ET tubes are secured during endoscopy?
prevention of tracheal trauma when scope is moved in and out
what must be recorded about scope procedures?
patient
area
indications
complications
biopsies and device used
how can scopes be cleaned?
ethylene oxide gas sterilisation
approved disinfectant
how should scopes never be cleaned?
autoclave
what must be done with all scopes immediately following use?
ensure channels are clear by flushing through air and water
