Thoracic Surgery and Anaesthesia Flashcards
what does ipsilateral mean?
the same side
what is modified transudate?
fluid formed by leakage from normal/non-inflamed vessels
what is orthopnea?
when an animal adopts a particular positional orientation in order to breathe - often sternal with forelimbs, head and neck extended
what is parenchyma?
tissue of an organ (not including connective tissue)
what is pleural space?
the ‘potential’ space between visceral and parietal pleura which is filled with fluid/air with effusions/pneumothorax
what does radiolucent mean?
transparent to x-rays (doesn’t show up)
what does radiopaque mean?
opaque to x-rays (e.g. bone)
what is a TFAST?
thoracic focused assessment with sonography for trauma
what is a thoracostomy tube?
chest drain
what is transudate (pure)?
passive fluid accumulation e.g. with hypoproteinaemia
what type of thoracic pathology can cats be prone to?
mediastinal masses (thymoma/lymphoma)
what type of thoracic pathology can yorkies be prone to?
tracheal collapse
what type of thoracic pathology can pugs be prone to?
lung lobe torsions
what type of thoracic pathology can afghan hounds be prone to?
chylothorax
what type of thoracic pathology can ESSs be prone to?
foreign bodies
what clinical signs can indicate an animal might have a lower thoracic condition which might be surgical?
tachypnoea
abnormal breathing
pale MM, cyanosis
exercise intolerance, collapse
+/- cough
+/- injuries
+/- systemically ill
what types of abnormal breathing might we see in a patient with a thoracic condition?
orthopnoea
hyperpnoea
dyspnoea
abdominal breathing
what are the main aspects of preliminary management for patients with thoracic conditions?
minimise deterioration
monitor closely
how can we minimise deterioration in a patient with a thoracic condition?
oxygen supplementation
assessment and management of any thoracic wounds, protect from ongoing damage
what are the available methods of oxygen supplementation?
flow by
nasal cannula
face mask
oxygen collar
oxygen cage
intubation
how should we monitor patients presenting with possible thoracic conditions?
assess patient temperament, consider sedation if required
identify upwards/downward trends in condition
what diagnostics are beneficial to run ASAP if a patient presents with possible thoracic issue?
lab work - bloods, thoracocentesis for C+T
imaging - TFAST
why should we have care with radiography in a dyspnoeic patient?
restraint for radiography in conscious animals can be very stressful and make condition worse, esp cats
what is the advantage of TFAST?
quick way for triaging nurse to determine how urgently a case requires vet attention
what is required to determine if a pleural effusion is present/what it is?
imaging
thoracocentesis and lab analysis
what is important to quickly determine with a pneumothorax?
whether the chest is closed or open
what is important to consider in cases where thoracic trauma may have occurred?
skin may or may not be broken
broken ribs might puncture a lung
what thoracic pathology can be delayed in cats after RTA?
diaphragmatic hernia
name some of the common surgical thoracic conditions
pneumothorax
chest/lung trauma
pulmonary blebs or bullae
diaphragmatic rupture
pleural effusion
pyothorax
pericardial effusion
pulmonary neoplasia
which of the common surgical thoracic conditions does not have a thoracic approach during surgery?
diaphragmatic rupture - abdominal approach
what types of fluid might be seen in pleural effusion?
septic and non-septic exudates
transudates and modified transudates
blood
chyle
neoplastic effusions
what are the clinical signs of pneumothorax?
dyspnoea
lethargy
cough
exercise intolerance
what are the possible aetiologies for an open (‘external’) pnemothorax?
chest trauma e.g. dog attach
iatrogenic e.g. post lung-lobectomy, diaphragmatic rupture, complications of thoracocentesis/thoracostomy
how can we diagnose a pneumothorax?
imaging - determine if unilateral/bilateral
thoracocentesis
why might a bilateral pneumothorax still require bilateral chest drains?
if the mediastinum is still intact
how can we conservatively manage pneumothorax?
chest drain - only if air leak might spontaneously seal
when would a pneumothorax require surgical treatment?
if large air leak or if ongoing and not sealing itself
what are the treatment options for pneumothorax?
chest drain
thoracotomy
what are the possible aetiologies for chest and lung trauma?
accident - RTA, fall, hit by train/car, impaling or run-on injury
attack - animal, human
what are the clinical signs of chest/lung trauma?
shock - big component
dyspnoea
soft tissue damage - open, bruising/crushing wounds
ortho damage - rib fractures/flail chest
what is the most important part of treatment for chest/lung trauma cases?
stabilisation before any GA/surgery
what are the common complications seen with chest and lung trauma cases?
infection - depends on cause/degree of contamination and presence of devitalised tissues
healing - delayed/breakdown
effusion - depends on amount of trauma/tissue injury
what is the prognosis for chest/lung trauma cases?
very dependent on severity of injuries
cost can also be a limiting factor
what is the signalment for pulmonary blebs and bullae?
large breed, deep chested dogs
what is the aetiology of pulmonary blebs and bullae?
unknown cause
often no concurrent lung disease
what are the clinical signs of pulmonary blebs and bullae?
often none if haven’t ruptured
some non-specific signs - lethargy, anorexia, exercise intolerance
what are the respiratory signs of pulmonary blebs and bullae?
sudden onset dyspnoea with no history of trauma
what are the progressive signs of pulmonary blebs and bullae?
tachypnoea/orthopnoea/coughing
what are the peracute signs of pulmonary blebs and bullae?
spontaneous closed tension pneumothorax due to rupture of blebs/bullae
how can we diagnose pulmonary blebs and bullae?
radiographs and CT
what can radiographs assess about pulmonary blebs and bullae?
can diagnose pneumothorax but not helpful for showing which lobes affected
what can CT show about pulmonary blebs and bullae?
used to assess which lung lobes affected - ideally done before surgery attempted
what are the treatment options for pulmonary blebs and bullae?
conservative - intermittent thoracocentesis/indwelling chest tube
surgery - open sternotomy/thoracoscopy
what is involved in surgery for pulmonary blebs and bullae?
removal of the affected lung lobes - feasibility depends on number affected
what is the aetiology for diaphragmatic rupture?
blunt force trauma- RTA/fall/blow to abdomen
how does a diaphragmatic rupture form?
increased abdominal pressure with closed glottis - diaphragmatic muscle is the weakest link and pops through into chest, allowing organs to move forward
how can we improve dyspnoea in patients with diaphragmatic rupture?
raise the thorax to allow abdominal contents to leave the chest
what are the clinical signs for chronic diaphragmatic rupture?
none or vague ill-health
what are the clinical signs of acute/peracute diaphragmatic rupture?
depends on severity -
degree of herniation/size of tear and which organs involved
tachypnoea, orthopnoea
concurrent ortho injuries
how is diaphragmatic rupture different from PPDH?
congenital diaphragmatic hernia is atraumatic and associated with animals under 2 years old
what is the treatment for diaphragmatic rupture?
stabilisation - oxygen, analgesia, IVFT
exploratory surgery of chest and abdomen
why do diaphragmatic rupture patients require a chest drain after surgery if the approach is abdominal?
the moment the abdomen is opened we create an iatrogenic pneumothorax through the rupture
what is the aetiology of pleural effusion?
many possible different reasons
what are the clinical signs of pleural effusion?
dyspnoea
lethargy
cough
exercise intolerance
how can we diagnose pleural effusion?
imaging
thoracocentesis
lab work
what lab analysis might we do on fluid from pleural effusion?
specific gravity to identify whether transudate/modified transudate/exudate
cytology
C&S
what are the non-surgical conditions related to pleural effusion?
CHF
pyothorax (cats)
when might we surgically treat pleural effusion?
where conservative management unlikely to be successful and/or has failed
usually pyothorax in dogs or diaphragmatic rupture
what is the aetiology of pyothorax?
bacterial infection
which types of pyothorax are likely to try and be managed medically?
idiopathic pyothorax in cats - often from bites, extension from pulmonary abscesses
which types of pyothorax are likely to be managed surgically?
those in dogs - usually FBs, oesophageal tears, pulmonary infections
what are the common bacteria causing pyothorax in dogs and cats?
e coli in dogs
pasteurella in cats
what are the clinical signs of pyothorax?
lethargy, inappetence, PUO
dyspnoea due to purulent effusion
can be mild or severe
how can we diagnose pyothorax?
labs - cytology and C&S of effusion
imaging - radiographs, U/S
what is involved in medical management of pyothorax?
systemic abs, chest drain +/- lavage
what is involved in surgical management of pyothorax?
sternotomy - explore, remove, debride, flush and post-op medical management
why is surgery often carried out early on in dogs with pyothorax?
because of likelihood of a FB
what is aetiology of pericardial effusion?
idiopathic or neoplastic - makes large difference to signalment and presentation
what are the clinical signs of pericardial effusion?
cardiac tamponade - severity depends on how quickly the effusion forms
why is degree of cardiac tamponade with pericardial effusion dependent on how quickly the effusion formed?
affects how well the pericardium will have been able to adapt and stretch
idiopathic (slow-forming) - less severe
acute/peracute - severe tamponade
how is pericardial effusion diagnosed?
labs - cytology to rule in/out neoplasia
imaging - radiography/echo/advanced imaging
which aetiology for pericardial effusion has the poorest prognosis?
neoplasia
what is the treatment for pericardial effusion?
repeated pericardiocentesis
surgery - pericardectomy
chest drain
does pericardectomy resolve issues surrounding pericardial effusion?
no - just prevents the cardiac tamponade and converts into pleural effusion
what are the complications of pericardial effusion treatment?
recurrence both after draining and surgery
long-standing effusion causes ahesions
what is the aetiology of pulmonary neoplasia?
malignant - benign
metastatic - primary
what are the clinical signs of pulmonary neoplasia?
vague - non-productive cough, haemoptysis, dyspnoea, non-specific weight loss and anorexia, exercise intolerance
lameness (hypertrophic pulmonary osteopathy - paraneoplastic syndrome)
often no signs (25%)
how can we diagnose pulmonary neoplasia?
lab - min database of biochem, haem, urinalysis
+/- cytology
imaging - advanced (CT), 3 view radiographs
what is the treatment for pulmonary neoplasia?
palliative
thoracotomy for lung lobectomy
what is the prognosis for pulmonary neoplasia?
guarded - depends on presence of mets, histopathology, clean vs dirty surgical margins
what are the pre-emptive nursing considerations for patients undergoing thoracotomy?
multi-modal analgesia
management of hypothermia
prep for IPPV once thorax opened
what is important to monitor in thoracotomy patients?
TPR
regular pain scoring so can discuss adjusting analgesia with vet
post-op wound healing and management
why might we put a body bandage on a thoracotomy patient?
for increased comfort
to reduce risk of infection
to reduce risk of patient interference
what is important to remember when nursing thoracotomy patients in hospital?
don’t forget patients need help with basics - EDUF, may need Ucath, feeding tubes
IVFT to take into account fluid losses
what are fenestrations (in regards to chest drains)?
holes in chest drains that enable fluid/air to be withdrawn - MUST be within the chest to avoid iatrogenic pneumothorax
what are flange?
side tabs that allow for simple suturing of narrow bore chest drains to skin
what is thoracocentesis?
procedure involving the puncture of the pleural space for diagnostic and/or therapeutic purposes
what should we make sure we are prioritising during thoracocentesis?
performing safely - remember patient requires oxygen
sterility - skin prep, gloves, sterile drape/glove packet
what equipment should be prepared for a diagnostic thoracocentesis?
oxygen!!
short-acting LA +/- anxiolytic
sterile prep equipment
needle/IV catheter/butterfly catheter
3-way tap and 20ml syringe
+/- extension set
kidney dish/jug
lab equipment
what do we need to consider in terms of sample handling for thoracocentesis?
tubes - EDTA, heparin, plain tubes for cytology/biochem/culture
culture sample must be collected straight from collection equipment and not touch kidney dish
make fresh smear for cytology
check USG before sending
+/- diffquik
what is a chest drain?
a tube placed into the pleural space to allow ongoing, continuous or intermittent therapeutic drainage
what factors might determine whether a chest drain is placed over intermittent thoracocentesis?
underlying disease (whether production continuous)
quantity of air/fluid being produced
patient temperament
treatment plan (if likely to have thoracotomy)
when is a chest drain usually placed?
when intermittent thoracocentesis not working
following thoracotomy
if long-term pleural drainage required
instillation of medications
why might a chest drain be placed following thoracotomy?
remove air/fluid introduced during surgery
detect air/fluid being produced due to underlying condition
detect air/fluid being produced due to complications of surgery
when might intermittent thoracocentesis not be appropriate?
large volumes of air/fluid being produced
fluid too thick to come through butterfly
proving too risky - causing lung trauma
why might long-term pleural drainage be required?
pneumothorax due to underlying lung disease
pleural effusion e.g. pus/chyle
which chest drain types require GA?
large bore
what are the general sizes for chest drains?
large bore and narrow bore
what are the placement techniques for large and narrow bore chest drains?
large bore - trocar technique
narrow bore - seldinger technique
what size chest drains are typically available?
6Fr to 20Fr
what does the size of chest drain selected depend on?
reason for drainage
amount expected
how is french scale for chest tubes different to ET tube sizing?
french scale is 3x the outside diameter in mm
3mm tube = 9Fr
can chest drains be placed into closed chests?
yes (trocar?) but requires significant skill to do so
how do we measure chest drain length?
pre-measure so tip sits cranioventrally but not too close to the thoracic inlet
what is important to remember about fenestrations on chest drains?
when drain is placed, all fenestrations must be completely within the chest
why should we check the integrity of all the connectors of the chest drain before it is placed?
to avoid iatrogenic pneumothorax
how are trocar drains typically secured?
using roman sandal style sutures
how are seldinger-type drains usually secured?
usually come with built-in anchor flanges to facilitate securing to the body wall with simple sutures
how can we protect chest drains?
24-hour nursing
gate clamps
secure sutures
body bandages and buster collars
when are trocar drains most commonly placed?
post-procedure, under GA
are trocar drains fenestrated?
yes
why do trocar drains require a subcut tunnel?
air leaks common
how can we reduce risk of air leaks with a trocar drain?
ensure placed through subcut tunnel
what are the advantages of trocar chest drains?
lots of different sizes available
versatile - good for air/fluid, not easily blocked
robust/rigid, unlikely to collapse
once learned, easy to place
easy monitoring of tube due to transparency
what are the disadvantages of trocar chest drains?
typically need GA to place
possibly higher complication rate than narrow bore (published evidence minimal)
needs careful training for placement and anchoring (sutures)
less comfy than narrow bore
what are the advantages of narrow bore (seldinger) chest drains?
no GA required
easy to place and secure
versatile
more comfy
what are the disadvantages of narrow bore (seldinger) chest drains?
may not cope with pleural fluid/block (e.g. pyo)
smaller sizes difficult - may be overlong meaning too much inside chest (may kink) or outside chest (patient interference easier)
lack of rigidity means can end up in weird placement - can be difficult to position cranioventrally
may not be able to do the normal SQ tunnel in large patient as introducer catheters not very long
when is a pleuraport used?
palliative care where long-term drainage required
what is required to drain a pleuraport?
special Huber Point needles
what equipment is required for placing a chest drain into a closed chest?
sterile prep equipment
anaesthetic kit and monitoring
assistant
chosen pre-measured chest drain
basic instrumentation, scalpel and blade
fenestrated drape
3-way tap
syringes
extension set
kidney dish/jug
suture material
what are the drainage options for chest drains?
intermittent or continuous
how often is intermittent drainage typically carried out?
4-8 hours and/or determined by resp rate/dyspnoea
when is continuous drainage commonly used?
with large air-leak pneumothorax cases
how can we reduce infection risk for patients with a chest drain?
aseptic technique at all times
good bandage hygiene
early identification for culture rather than just giving antibiotics
what can be used as part of multi-modal analgesia for patients with a chest drain while hospitalised?
local e.g. lidocaine
systemic opioids
local down chest drain e.g. bupivacaine
CRIs
paracetamol inj (dogs only)
what medications are patients with a chest drain typically send home with?
NSAID
oral paracetamol (not cats)
what are the possible complications of chest drains?
failure to place
failure to drain
patient interference
iatrogenic issues
infections
what issues with placement may arise during chest drain placement?
physically unable to place
incorrect placement (caudal not cranial/didn’t enter thorax/stuck in mediastinum)
how can we check chest drain placement?
x-ray post-placement
why might a chest drain fail to drain after placement?
inadvertent/accidental removal
tube disconnection/obstruction/kinking
tube slipped out a little (care not to break sterility of tube if adjusting)
what iatrogenic issues can occur due to chest drain placement?
haemorrhage/haemothorax
heart/lung damage
inappropriate/premature removal –> recurrence
nerve damage (phrenic/Horners)
pneumothorax
pyothorax
seroma (often due to high volume effusion rather than truly iatrogenic)
subcut emphysema
why might a vet decide to keep a chest drain in?
ongoing treatment via the drain
clinically significant production of air/fluid
why might a vet decide to remove a chest drain?
complications where risk of tube remaining is greater than removal risks
resolution of issue (reduced volume)
ongoing need for drainage (switch to pleuraport)
what should we consider in terms of preparation for thoractomy?
patient stability - risk assessment, ASA grading, bloods, IVFT
analgesia and abs - pre-emptive and perioperative plan
surgical plan - approach, kit, specialised instruments, potential complications and management of them
what are the main 4 approach options for thoracic surgery?
left lateral intercostal thoracotomy
right lateral intercostal thoracotomy
vental sternal thoracotomy/sternotomy
thoracoscopy
what is a thoracotomy defined by (numerically)?
numbered rib space
what is the advantage of an intercostal thoracotomy?
less painful than sternotomy
what must we consider when choosing a lateral approach to thoracotomy?
need to be sure that condition can be treated with unilateral surgery
need to be sure of the correct side to approach
need to be sure of the correct intercostal space to use
what are the disadvantages of median sternotomy?
more painful than thoracotomy
not appropriate if issue is in dorsal thorax
what procedures is a median sternotomy more appropriate for?
exploratory thoracotomy
bilateral conditions
why is thoracoscopy not commonly used?
steep learning curve
specialised equipment required
reduced visualisation
limitations in which procedures can be safely completed using a scope
how is the thorax accessed during a median sternotomy?
osteotomy with saw blade
how wide should the clip be for a median sternotomy?
from thoracic inlet to mid abdomen, at least to width of axilla
how wide should the clip be for thoracoscopy?
fully clipped as for sternotomy in case have to convert to open surgery
how should the patient be positioned for a lateral thoracotomy?
front legs +/- back legs loosely tied out of the way
+/- sandbag under chest
how should a patient be positioned for a median sternotomy?
dorsal recumbency, legs tied loosely out of the way
may need cradle and/or sandbags to stabilise if narrow chested
how should patients be positioned for thoracoscopy?
can be done in lateral or dorsal depending on procedure
how can thoracic surgical instruments be easily identified?
much longer handles than standard instruments (tissue forceps, scissors, needle holders)
what are the purposes of tissue forceps during thoracic surgery?
atraumatic tissue handling
atraumatic fine dissection
clamping vessels prior to ligation
what are sternotomy instruments used for?
to break through the bone
which types of retractors may be used during thoracic surgery?
handheld e.g. malleable, langenbeck
ratcheted e.g. finochietto, gelpis
which tissue forceps may be used during thoracic surgery?
debakeys - atraumatic
vascular/statinsky/soft palate clamps - for vessels prior to ligation
right-angled clamps - useful for dissection, come with/without ratchet
what are the options for osteotomy during a sternotomy?
manual - chisel and hammer
electrical - oscillating saw
which other miscellaneous items might be required during thoracic surgery?
lap swabs and suction
wire/thick suture
pre-selected chest drain and connectors
tourniquet
pledget sutures
vessel loops
what is classed as basic electrosurgery?
monopolar and bipolar diathermy
what is classed as advanced electrosurgery?
gen11
ligasure
harmonic
what is the advantage of bipolar diathermy?
no earthing pad required to avoid burns
what is a pneumonectomy?
removal of one half of the lungs
how well do patients cope with pneumonectomy?
surprisingly well - remaining lung expands to fill the chest
what is the disadvantage of lung lobectomy using sutures?
slow, technically challenging, higher risk of leakage
what is the advantage of lung lobectomy using staplers?
quick, lower risk of leakage
what are the disadvantages of lung lobectomy using staplers?
more expensive to keep in stock
steep learning curve
what procedure should always be performed after a lung lobectomy?
leak testing
how is leak testing carried out?
chest is filled with warm saline, suction on standby
IPPV and check for air bubbles
suction fluid back out once happy no bubbles are passing
why does opening of the thorax give specific anaesthesia considerations?
it removes the negative pressure in the pleural space, meaning the lungs cannot expand on their own
why can’t the lungs expand when the negative pressure in the pleural space is removed?
when the chest wall expands, there will be little/no air entry into the lungs because the pressure inside the lungs is the same as atmospheric pressure
what does opening of the thorax during anaesthesia lead to?
inadequate ventilation and impaired gas exchange
requires IPPV
what happens to the structure of the lungs when the thoracic cavity is opened?
atelectasis (small airway collapse)
what happens to the lung capacities when the thoracic cavity is opened?
decreased:
total lung capacity
vital capacity
functional residual capacity
what might occur during thoracic surgery to exacerbate hypoxaemia?
packing off lung lobes - direct pressure on lungs
manipulation of major blood vessels
leak testing exerts pressure
which thoracic approach is more painful?
sternotomy
why is thoracoscopy less painful than sternotomy?
less invasive, should be associated with less pain than a fully open procedure
how should ventilation be managed in diaphragmatic hernia cases?
treat as thoracotomy and ventilate from start - chest wall compromised
why is thoracotomy painful?
large skin incision
nerve trauma and muscle damage due to extensive retraction
inflammation at surgical site
all leads to hyperalgesia
why is post-op hypoxaemia common after thoracotomy?
unwillingness to move the chest wall due to pain leads to reduced efficacy of ventilation
what are the respiratory system-related reasons for opening the thorax?
lung lobe torsion, bulla, neoplasia, abscess etc
what are our considerations for opening the thorax for respiratory system surgery?
pre-existing pneumothorax hypoventilation
hypoxaemia
what are the cardiovascular system-related reasons for opening the thorax?
patent ductus arteriosus
persistent right aortic arch
pericardectomy
heart surgery
what are our considerations for opening the thorax for cardiovascular system surgery?
cardiovascular changes
bleeding
hypotension
risk of arrhythmias
what are our specific considerations for persistent right aortic arch?
often present with regurgitation
predisposes aspiration
young patients - risks associated
what are our main anaesthetic consideration for patent ductus arteriosus?
altered movement of blood - abnormal circulation, hypotension
systemic blood pressure increase when vessel ligated –> profound bradycardia
what are our anaesthetic considerations for oesophageal FB, thoracic duct ligation etc?
risk of aspiration
risk of regurgitation
septic complications - often contaminated surgery
post-op pain management vital
which risks do we need to be aware of pre-GA for thoracic patients and how do we mitigate these?
bleeding - blood type, check blood availability
hypotension - fluids/drugs, make a plan with vet
hypoventilation - oxygen, IPPV
which equipment is it vital to check before GA for thoracic surgery?
facilities for IPPV - check ventilator
check monitoring equipment
what type of blood pressure measurement is ideal under GA for thoracic surgery?
direct continuous via an arterial line
which parameter is important to monitor in neonates/septic patients undergoing thoracic surgery?
blood glucose
what might be involved in pre-anaesthetic support/stabilisation?
chest drainage where applicable
pre-oxygenation if not causing more stress
analgesia
what type of drugs should be avoided for pre-med in thoracic cases?
a2 agonists and ACP - most patients will be too unstable
what is an appropriate pre-med plan for an unstable thoracic surgery patient?
methadone only
what are the aims of our drug choices for thoracic surgery patients?
minimise CVS depression
which drugs should we prepare in advance for thoracic surgery?
consider whether inotropes are likely indicated
prepare infusions of analgesics e.g. fentanyl
what is etomidate?
an IV, ultra-short-acting, nonbarbituate hypnotic drug
what is etomidate used for?
widely used in man as a induction agent and by continuous infusion
is etomidate licensed for any animal species?
not in UK
what are the major advantages of etomidate use in thoracic cases?
minimal cardiopulmonary depression - produces minimal change in HR, MAP or myocardial performance
what is the main disadvantage of etomidate use?
quality of induction is poor - not smooth, vomiting
what are the respiratory effects of etomidate?
similar to those of thiopentone and propofol
what is the major benefit of fentanyl usage in thoracic cases?
it is a potent anaesthetic sparing drug - minimises dose-dependent CVS/respiratory depression due to inhalant drugs
what is the onset and duration of action of fentanyl?
onset within 5 mins
duration 20-40 mins (dose-dependent)
when is one lung ventilation used?
when pathology affects one lung but not the other e.g. infection or tumour
to improve surgical exposure e.g. in thoracoscopy
what special equipment is used for one lung ventilation?
a double lumen tube or endobronchial blocker
why is one lung ventilation rarely carried out?
placement is difficult and effects of incorrect placement can be catastrophic
what is the advantage of performing one lung ventilation using a single lumen ET tube?
easier to perform than other methods
what are the disadvantages of performing one lung ventilation using a single lumen ET tube?
may not achieve effective one lung only ventilation
risk of contamination between lungs
difficult in bigger dogs (>20-25kg) due to tube length
what is the advantage of performing one lung ventilation using an endobronchial blocker?
results in effective one lung ventilation
what are the disadvantages of performing one lung ventilation using an endobronchial blocker?
requires a bronchoscope to place and skill/training
expensive to buy
what is the advantage of performing one lung ventilation using a double lumen ET tube?
can be done blind
what are the disadvantages of performing one lung ventilation using a double lumen ET tube?
tubes are bulky and can be difficult to place
not achievable in dogs >20-25kg due to tube length
what are the considerations for one lung ventilation using an endobronchial blocker?
only use stated inflation volumes for cuff of blocker to prevent bronchial wall damage
only inflate cuff when OLV is required
avoid moving patients when blocker is placed/inflated
why should moving patients be avoided once an endobronchial blocker is placed?
increased risk of dislodgement if moved
why should moving patients be avoided when an endobronchial blocker is inflated?
increased risk of bronchial wall damage if moved
what care considerations are there for OLV with a double lumen ET tube?
care needs to be taken when moving patient - can become easily dislodged
deflate cuff before moving
what is the ideal tidal volume range on a ventilator?
10-15ml/kg
(8-10 in cats?)
what is the ideal peak inspiratory pressure range on a ventilator?
8-12cm H2O
what is the ideal RR range on a ventilator?
10-30mpm
what is the ideal I:E ratio on a ventilator?
1:2 max
how can we assess appropriateness of tidal volume on a ventilator?
visualisation - observation of the thorax
adapt with monitoring
how can we assess appropriateness of peak inspiratory pressure on a ventilator?
adapt to open/closed thorax
increased if recruitment
how can we assess appropriateness of RR on a ventilator?
adapt to animal
increase if tidal volume is decreased
how can we assess appropriateness of I:E ratio on a ventilator?
adapt according to RR
why does care need to be taken with volumes used on a ventilator?
to avoid barotrauma or volutrauma
limit pressure/volume applied to the chest
how does re-expansion pulmonary oedema occur?
due to rapid overexpansion of lungs at end of surgery
how can we avoid re-expansion pulmonary oedema?
be careful at end of surgery not to over expand lungs - especially if compressed for extended period e.g. thoracic tumour
why are differences between ETCO2 and PaCO2 not consistent in dogs with an open thorax?
due to altered ventilation and perfusion (VQ) relationships
how can we check the efficiency of ventilation/perfusion under GA?
measure PaCO2
what is the minimum oxygen monitoring requirement during thoracic surgery?
SpO2 should be the minimum - PaO2 if possible
how can we detect hypoxaemia during thoracic surgery?
requires placement of an arterial catheter
during which thoracic surgery is it mandatory to place an arterial catheter?
thoracoscopy - detection of hypoxaemia
how can we manage hypoxaemia during thoracic surgery?
check 100% FiO2
check patency of ET tube
ensure CVS function is optimised
switch to manual ventilation temporarily - perform alveolar recruitment manoeuvre
introduce PEEP
reduce concentration of volatile agent, intro CRI
re-expand collapsed lung
how can patency of the ET tube affect hypoxaemia?
endobronchial blocker may be dislodged
secretions blocking lumen of tube
how can we ensure CVS function is optimised during thoracic surgery?
appropriate depth of anaesthesia
circulating blood volume is adequate
confirm that surgeon is not decreasing VR (hand/arm/leaning on chest)
why can switching to manual ventilation help with hypoxaemia?
to give a few larger breaths - can decrease atelectasis
can perform alveolar recruitment manoeuvre
what other supportive therapies should be considered for thoracic surgery?
fluid therapy
management of hypothermia - large wound, minimise losses, warm fluids
what are the options for analgesic management during thoracic surgery?
combination of local and systemic analgesics
full mu agonists
epidural morphine
intercostal nerve block (lateral thoracotomy)
LA down the chest drain (bupivacaine)
NSAIDs for management of blood pressure
why should use of NSAIDs be carefully considered in thoracic patients?
due to reduced CVS function - ensure BP maintained, avoid in patients at risk of/with hypotension
consider on recovery if stable
how can we aid pulmonary expansion when weaning patients from a ventilator?
consider an alveolar recruitment manoeuvre
what are patients more at risk of developing after >12 hours on a ventilator?
pulmonary oedema if tried to wean off too quickly
when should we time end of IPPV when weaning a patient off a ventilator?
time end of IPPV with closure of the chest and drainage of the chest - won’t be able to breathe spontaneously otherwise
when is an alveolar recruitment manoeuvre particularly useful?
if lavage atelectasis has occurred
what are the most important steps involved in weaning a patient off a ventilator?
turn off the ventilator and support respiration until breathes spontaneously
decrease IPPV gradually - will allow PaCO2 to rise
decrease anaesthetic/analgesic drugs
reverse NMBA before stopping IPPV
how can we ensure the patient is weaning back onto room air efficiently?
use a pulse ox to measure
supplement oxygen if not saturating adequately
check chest drain for blood/fluid/air if not saturating
why should we avoid long term high concentration oxygen supplementation?
can cause oxygen toxicity >6 hours
which blood parameter should we consider monitoring after thoracic surgery?
monitor PCV, check PCV of fluid in the chest drain to see if actively bleeding
consider transfusion if necessary (>20% blood loss)
what are the overall key factors for thoracic surgery?
IPPV
good pain management
basic life support (fluids/temp)
robust anaesthesia protocol
