Thoracics Flashcards
1
Q
What’s the correct size for a l-sided dlt?
A
Bronchial tip 1-2mm narrower than L) main bronchus diameter, allowing for the deflated cuff
2
Q
What size dlt for a <160cm female?
>160cm? <170cm male? >170cm male?
Females <152cm? Males <160cm?
A
35,37,39,41
Look at ct, consider size 32fr for female, 37 for male
3
Q
What’s the correct depth for a dlt?
A
12+(height/10) cm @ teeth EXCEPT in Asian ppl (height not such a good predictor- risk rupture L) mainstem bronchus)
about 27-29cm
4
Q
How far from the carina does the r) ul bronchus originate?
A
1.5-2cm
5
Q
What’s the only structure in the tracheobronchial tree with 3 orifices?
A
R) UL bronchus ; anterior, apical, posterior
6
Q
What are the absolute indications for one lung ventilation?
A
- Prevent damage or contamination of the healthy lung (eg. bronchopleural fistula, pulmonary haemorrhage or lung abscess, whole-lung lavage)
- Control distribution of ventilation (bronchopleural fistula, major unilateral cyst or bulla, surgical opening of major conducting airway, traumatic bronchial disruption, life-threatening hypoxaemia due to unilateral lung disease, provide differential patterns of ventilation in unilateral reperfusion injury eg. lung transplant, pulmonary thromboarterectomy)
- Unilateral bronchopulmonary lavage (CF, pulmonary alveolar proteinosis)
- provide surgical access for one-lung ventilation in thoracic aneurysm/pneumonectomy/thoracoscopy procedures involving chest cavity
- unilateral lung trauma
7
Q
What are the relative indications for OLV?
A
Strong indication: Improve surgical access for (high priority):
-Thoracic aortic aneurysm (these days an absolute indication, given with the heparinisation there’s too much trauma to the lung)
-pneumonectomy (now always done with OLV)
-upper lobectomy
-mediastinal exposure
-thoracoscopy (even lobectomies can be done this way, VATS- this is now also an absolute- can’t do videoscopic surgery without good lung isolation)
-lung volume reduction surgery
-minimally invasive cardiac surgery
8
Q
What are the weaker relative indications for OLV?
A
To improve surgical access for:
oesophageal surgery
mediastinal mass reduction
middle & lower lobectomy or sub segmental resection
procedures on Tx spine
9
Q
What are the 3 available techniques for OLV?
A
DLT
bronchial blocker
Univent tube
single lumen tube advanced into the L) or R) main-stem bronchus (endobronchial tube)
10
Q
What are the indications for a R)-sided DLT?
A
Surgery involving the L) main bronchus (eg. L) pneumonectomy, L)-sided thoracoscopic surgery, L) lung transplant, L) trachobronchial disruption), distortion of the L) main bronchus anatomy (eg. extrinsic compression from descending Tx aortic aneurysm, extra- or intraluminal tumor compression)
10
Q
Why is L)-sided thoracoscopic surgery an indication for R)-sided DLT?
A
*should always cannulate the dependent lung. tube always more stable in the operative field.
thoracoscopic instruments can be long & manipulation of the L) mainstem bronchus can be challenging if tube in situ. if the pt is in L) lateral & side flexed, there can be compression of the distal trachea & difficulty adequately ventilating the R) lung with the tracheal lumen & air trapping is a risk
11
Q
What should the french scale of the DLT correspond to?
A
the external diameter of the tracheal segment, in mm, multiplied by 3
12
Q
What’s the process for confirming position of DLT?
A
3-step sequential clamping & auscultation then confirm with FOB (essential for R)-sided):
1. inflate tracheal cuff w the minimal volume to seal glottic air leak, PPV & ausc to confirm bilat air entry & ensure acceptable capnography trace
2. clamp tracheal lumen, inflate bronchial cuff w 1-3mL, PPV to confirm unilat air entry sans audible leak
3. unclamp tracheal lumen, ausc to confirm resumption of bilat air entry
FOB confirmation:
-insert through tracheal lumen to visualise carina, identify blue endobronchial cuff crest within L) main bronchus but not herniating over the carina
-for R)-sided DLTs, also insert FOB through endobronchial lumen & ensure murphy’s eye aligned with the R) UL bronchus
13
Q
What are some problems related to the use of DLTs?
A
- malposition- eg. if cuff overinflated & herniates out of bronchus or if head/neck excessively moved during repositioning
- airway trauma- eg. presenting as unexplained air leaks, subcut emphysema, blood in the tube, cuff appearing in surgical field
- tension PTx of the ventilated lung due to high ventilating pressures or large TVs, esp if the pt has pre-existing emphysema
14
Q
What french is the cohen blocker? what is the smallest recommended ETT for coaxial use?
A
9Fr, size 8 ETT
15
Q
What are some advantages of bronchial blockers?
A
-easy size selection, easy to use with a standard tracheal tube
-can ventilate during placement
-Useful for difficult airways (where DLT challenging), or where the patient has abnormal upper or lower airways, easier to place in small adults, children
-nasotracheal intubation
-useful in haemoptysis, trauma
-Postoperative dual ventilation easily by simply withdrawing the blocker
-RSI and OLV
-critically ill pts already intubated (eg. facial swelling)
-Selective lobar isolation/ventilation possible
-CPAP to isolated lung possible
16
Q
What are some disadvantages of bronchial blockers?
A
-relatively time-consuming to insert & accurately place
-placement variable (harder to guarantee integrity of isolation)- misplacement eg. in trachea may be dangerous if not identified rapidly.
-more frequent repositioning required
-FOB essential
-slow & incomplete collapse of lung
-suction not possible
-bronchoscopy of isolated lung impossible
-alternating side of OLV difficult with the exception of Rusch EZ-bifid blocker
-limited R) lung isolation due to R) UL anatomy
-failure to achieve lung isolation if abnormal anatomy has occurred
-need to communicate well w surgeons- cases of blocker or wire being included in staples.
There’s also a univent tube which is a modified SLT with separate channel for BB; requires less repositioning compared with standard BBs but the ETT portion has higher airflow resistance yet larger diameter than regular ETT
17
Q
What are advantages & disadvantages of lung isolation with an ETT advanced into a bronchus?
A
Easiest to place in airway emergencies or difficult airways
Suction/CPAP & bronchoscopy impossible to the isolated lung
Difficult for R)-sided OLV
the cuff is not designed for OLV unless a specific endobronchial tube
18
Q
What are the advantages & disadvantages of DLTs?
A
Quickest to place & rarely require repositioning
Can suction & bronchoscope & CPAP to the isolated lung
Have a built-in camera (with Viva-sight)
Versions for R) & L) available
Can alternate OLV to either side
best device for absolute lung isolation
Limited sizes available
Difficult to place in abnormal/distorted airways
difficult for difficult airways
Large & relatively traumatic (laryngeal, bronchial)
intraop displacement a risk
not ideal for postop ventilation
Can insert even if FOB unavailable but for R)-sided, FOB essential
19
Q
What are the dimensions of the aintree catheter?
A
56cm, 19Fr
20
Q
Which size tube fits over an aintree catheter?
A
size 7
21
Q
What depth should the AIC NEVER go beyond the lips?
A
26cm
22
Q
What’s the best LMA for use with AIC?
A
proseal
23
Q
What’s the safest lower limit of SpO2 during OLV?
A
> =90%
24
Why do SpO2 drop after the initiation of OLV?
HPV- biphasic, phase 1 begins within seconds & peaks @ 15 mins, phase 2 begins from 30-40mins & peaks at 2hrs
25
What's the first step to managing hypoxaemia during one lung ventilation? Which pts can't tolerate this?
Increase FiO2 to 1.0, NOT for pts who've received bleomycin for malignancy
26
What are the steps to managing hypoxaemia during OLV?
-if urgent, significant hypoxaemia, resume 2 lung vent
If gradual desaturation:
-FiO2 1.0 provided no bleo Hx
-recheck DLT/BB position w FOB & ensure no lobar obstruction
-ensure haemodynamics acceptable & CO optimal (eg. surgeon hasn't compressed IVC), treat any fall in CO & stop vasodilators (ensure MAC <1)
-recruitment maneouver to ventilated lung to eliminate atelectasis (risks worsening hypoxaemia if transient hypoT & more blood diverted to non-ventilated lung)- 20cmH2O for 15-20 seconds
-adjust PEEP to the ventilated lung. need to recruit before apply PEEP (would have recruited & put PEEP on when commenced OLV). effectiveness will depend on the patient (not for emphysematous pathology)- those with normal lung mechanics or restrictive pattern due to incr elastic recoil will have their end-exp volume brought toward the FRC so PaO2 likely imporve but not possible to predict the optimal PEEP for each pt- titrate. Aim PEEP 5-10 with driving pressure (required for alveolar opening, Pplat-PEEP) 15cmH2O or less.
PEEP has the benefit of not interrupting the surgical field. PEEP is as effective as CPAP for improving PaO2 during OLV for pts with normal lung function.
-can do apneoic oxygenation to the nondependent lung (3L/minO2 via a suction catheter to the non-ventilated lumen of DLT)
-If a DLT, insufflate the non-ventilated lung with oxygen to recruit it (need 20cmH2O to open alveolitic lung areas for CPAP to be effective) then apply 1-5cmH2O CPAP with O2. CPAP may not be completely effective eg. if bronchus of operated lung is obstructed or if open to atmosphere, CPAP won't improve oxygenation. CPAP also can interfere w surgery for VATs.
-Could try intermittent re-inflation of the non-ventilated lung (pre-condition the HPV reflex).
-could try intermittent positive airway pressure (eg 2 secs on, 8 secs off with 2L/min via CO2 port with HME filter over non ventilated lumen, or could selectively oxygenate specific segments remote from site of surgery (eg. intermittent insufflation of O2 using fiberoptic scope), or could put a blocker just for the lobe being resected while continuing to ventilate the other lobes or could do small TV ventilation eg. 70mLs with RR 6/min.
-if pneumonectomy or lung transplant planned or temporarily in emergency, surgeon could clamp a pulm artery to restrict perfusion to the non-ventilated lung.
-systemic vasoconstrictor (eg. phenylephrine) with inhaled pulm VD (eg. epoprostenol) to ventilated lung.
-dexmedetomidine may improve oxygenation index.
-VV ECMO if no other option.
-Resume 2-lung ventilation asap if severe desat.
27
What ventilator strategies are employed for lung-protective ventilation?
FiO2 as low as possible, low TVs (6mL/kg pred BW) to maintain peak airway pressures as low as poss not >35cmH2O, PEEP 5-8cmH2O (nil in COPD), frequent recruitment, permissive hypercapnia
28
What is the working port of the fibrescope used for?
O2, suction, LA injection
29
What's the Chula formula for length of nasal tube?
9+(height/10)cm
30
To which scenarios is AFOI best suited?
non-emergent approach to expected difficult airway, particularly anticipated difficult intubation, ventilation or unstable C-spine
31
What's the level of the carina?
T5, angle of Louis
32
Considerations for surgical correction of chest wall deformities
Patient: generally young, male (3:1 to 9:1). predominantly idiopathic & isolated, few (<5%) are associated with connective tissue disorders (eg. Marfan's) or musculoskeletal disorders (eg. Poland syndrome). May have psychological distress re: body image as indication for surgery. Few are symptomatic (breathlessness, palpitations, chest or back pain, pre-syncope/syncope); cardiac +/- lung compression.
Pathology: PE more common (87%) than PC (5%). Severity of pectus excavatum graded by Haller index; CT, divide lateral chest diameter by AP diameter, normal 2.56, considered significant if >3.25.
Procedure: Nuss= video-assisted thoracoscopc. Bilateral mid-axillary incisions. Retrosternal metallic bars inserted. Bars usually removed within a few years of placement.
Potential complications:
-intraoperative major haemorrhage: cardiac/vascular/liver injury or perforation
-bar slippage or misplacement- may cause trauma, cardiac compression or RVOTO
-minor pericardial tears, lung trauma & pleural or pericardial effusions (can be managed conservatively)
-CO2 insufflation into the chest can be used to generate a PTx; may be used in addition to OLV or as an alternative to lung isolation- monitor to avoid excessive intrapleural pressure/tensioning/mediastinal shift
-brachial plexus injury with arms abducted & Tx bolster- care w UL abduction (open repair doesn't always require UL abduction)
-expectation of significant pain
-residual PTx (require a CXR in PACU)
PRE-OP:
C:
Hx of allergies (particularly to metals), cardioresp systems, genetic syndromes
Exam: cardiorespiratory
Ix:
-ECG
-FBC
-U&Es
-G&H (high risk major haemorrhage)
-chest imaging particularly wrt position of heart & great vessels (displacement/compression), RV compression is common but not usually clinically significant, if severe may develop outflow obstruction. Mitral valve prolapse with MR is also common (20-40%) due to mechanical distortion of the mitral annulus.
Additional tests MAY be warranted depending on particular symptom indication:
-echo useful for vent fn, valvular (esp mitral) insufficiency, detect RV compression
-PFTs: useful for pts c/o resp symptoms, may be normal or may show restrictive defect
O:
Premed/planning:
-Tertiary centre
Explain/consent:
INTRA-OP:
Monitoring: art line, CVC or TOE usually unnecessary unless complex repair/pt comorbidities
Assistant
Drugs
-premed case-by case; anxiolysis, consider a single dose of gabapentin (10-15mg/kg max 900mg PO, 1hr preop) as may reduce postop pain & opioid use
REGIONAL: either pre-op thoracic epidural T3-5 (benefit of intra & postop analgesia, failure rate approx 30% across all specialities), bilateral PVB (lower incidence adverse effects incl urinary retention & hypoT), ITM (only useful for up to 24hrs), pecs or SAP blocks, ?ESP blocks
TIVA or volatile, avoid N2O (risk expanding pneumothoraces)
NMBD (relax diaphragm)
Multi-modal analgesia: paracetamol, NSAID, dex, ketamine, ?lignocaine, clonidine, Mg++
Equipment
-choice of tracheal tube dictated by surgery- Ravitch doesn't require lung isolation (open OT), Nuss does (thoracoscopic)
A
B- OLV if Nuss
C- lg bore IVC
D
E
F
G
P- supine with bolster behind Tx spine
POST-OP:
-CXR in PACU (residual PTx)
-Adequate analgesia vital for pt recovery, participation in PT etc; continue multimodal along with PCA (pain often significant into day 2-3 so ensure don't de-escalate PCA too early). incentive spirometry, physio, encourage early mobilisation.
-generally disposition= ward
33
What are the objectives of DLT?
1. optimal gas exchange during OLV
2. allow operative lung to collapse
3. integrity of isolation: no spill over of ventilation, blood, pus
34
What FiO2 for OLV? TVs?
0.9, always leave some nitrogen
5-6mL/kg TVs
RR to potentially allow some permissive hypercapnia
some PEEP 0-5mmHg (lung protective vent, NO insp pressure >30mmHg)
35
Is TIVA better for HPV?
probably, particularly for transplant pts who don't have the pulmonary reserve to survive. Not as crucial for other lung surg if some resp reserve.
35
Is TIVA better for HPV?
probably, particularly for transplant pts who don't have the pulmonary reserve to survive. Not as crucial for other lung surg if some resp reserve.
36
postop priorities pneumonectomy
analgesia (minimise nadir with resp function)
fluid balance
mediastinum position
physiotherapy
avoid atelectasis/infection
37
how to manage air leak?
Pt booked for pleurodesis, he is a readmit 1/52 after a spont PTx- he has a 15% PTx, undrained. Issues are that may get a tension PTx or if the air leak is significant I may not be able to ventilate the pt. Therefore, I'll change my anaesthetic by: avoiding PPV- spont vent induction most likely sevo or with TIVA. I'd have the surgeon scrubbed in the room ready to assist if needs be with scrubbed field who could but in chest tube in (ideally their desired location of a VATS port).
If the pt has an IC tube in situ, I'd still do a spont vent induction as I can't say for sure if the drain will swing/is patent/draining or if I can definitely ventilate the pt.
38
What's an acceptable technique for a pt with difficult airway needing a DLT?
single lumen tube then railroad bronchocath DLT.
39
What are minimally invasive approaches to resection of mediastinal masses? invasive? Anaesthetic considerations?
cervical mediastinoscopy (midline transverse incision immediately above clavicular heads); 3cm, suprasternal notch
anterior mediastinoscopy (chamberlain procedure)- transverse incision immediately lateral to L) of sternum @ angle of Louie along 2nd CC
Procedure:
Chamberlain procedure more invasive
Pt positioned supine with shoulder roll under scapulae & neck extended
position of the mediastinoscope may impinge on nominate artery so may loose R) UL pulses, BP more accurately monitored on the L), can monitor R) UL pulse ox or art line to detect nominate compression
Potential complications:
all more common in anterior mediastinoscopy procedures
vascular injury, tracheal or oesophageal injury, PTx, RLN injury
Cervical relatively contraindicated in SVC syndrome (risk bleeding with distended vv), prev mediastinoscopy @ same site rel CI. severe trach deviation, cerebrovasc disease, severe C spine disease w limited neck E, prev chest RTx, thoracic aortic aneurysm all other rel CIs.
Thoracoscopy:
induction & intubation for single-lung ventilation (DLT or bronchial blocker), pt in lat decubitus with table broken to open intercostal spaces
Potential complications: PTx, chylothorax (tx duct), phrenic nerve injury, oesophageal perforation, bleeding from vascular injury (consider pre-op access all LL due to risk of disruption of vessels driaining into SVC), RLN injury, stroke, air embolism, oesophageal tear, tracheobronchial lac, conversion to open to improve surgical exposure is not uncommon.
Open approaches incl thoracotomy, sternotomy; anterior mediastinal masses crossing the midline require a sternotomy while those in one side only may be exposed adequately with hemi-clamshell incision, masses extending below pulmonary hill on both sides require a clamshell incision
Preop considerations:
bronchogenic carcinoma: often smokers, multicomorbid incl HTN, CAD, PVD
mediastinal mass concerns as above (most asymptommatic)
tracheobronchial compression predisposes to persistent RTI, wheeze, stridor
Awake or inhalational to maintain spont vent & -ve Pip (lost if decr chest wall tone & cephalic displacement of diaphragm)
if symptomatic w resp obstruction, AFOI, whole team see level ov obstruction, pass tube distal to obstruction. If very distal, have rigid bronch available.
Could use inhalational induction alternative w pt 20 deg head up (pre-oxygenate in position of safety)
d/w surgeons nature of lesion, ?stent before mediastinoscopy if significant obstructive symptoms?
sandbag, head up 20 deg.
reinforced may be useful to risk kinking intra-op.
if long-standing mass, fibreoptic at end to rule out tracheomalacia
prop/remi, NMBA if no MG.
wound LIA, superficial Cx plexus block or intercostal block help. paracetamol/nsaid.
CXR postop in PACU to exclude PTx.
HDU or ward depending on pt/procedure (day case if very minor), postop complications RLN injury or paratracheal haematoma.
PCV detects early rise in Paw.
40
Where to place vascular access in pts with SVC obstruction?
central femoral line PRIOR to induction (or 2x large-bore LL peripheral catheters)
If difficult IV access could place one draining into IVC (eg. femoral) & SVC (eg. IJ), so the IVC used during surgery until mass resected then SVC postoperatively
41
What’s cross-field ventilation?
When the surgeon places an ETT directly into the main conducting airway to ventilate airway distal to disrupted trachea (eg. Iatrogenic injury), run TIVA in this instance (depth of anaesthesia, limit VA to surgical team, discontinue N2O & FiO2 <30% or a minimum to avoid hypoxia (fire risk), allow adequate time for reduction in both FiO2 & FeO2 to safe level before electrosurgery or other ignition source.
42
For which pts with mediastinal masses is a CVC necessary?
Those who may develop airway obstruction +/- haemodynamic compromise from anaes or surgery
43
In which situations may automated computation of dynamic parameters to guide fluid therapy be limited? Useful surrogate?
-spont vent
-open chest
-high end-exp pressures (eg. >40mmHg)
-TVs <8mL/kg
Visualise respirophasic variation on art line trace- adequate estimate & may be comparable to automated values
44
What are the fluid goals with thoracic surgery?
Restrictive, since <=3mL/kg/hr hasn’t been ass’d w AKI after Tx surgery & excessive fluid ass’d with ALI & delayed recovery (don’t need to reverse oliguria with fluid administration)
Replace red cells only if Hb <80g/L, otherwise use colloids to replace blood loss
45
What are criteria for safe extubation?
Surgical: no factor requiring ongoing intubation eg. Excessive airway swelling, high bleeding risk, excessively prolonged surgery
Anaesthetic: full recovery of neuromuscular function to TOFR >0.9 & sedative/hypnotics adequately washed out
Pt:
Not hypoxaemic (ie. P:F ratio >=150, SpO2 >=90% on FiO2 <=40% & PEEP <=5
Normothermic
Acid-base status normal
Haemodynamic stability (no or minimal pressor)
Able to initiate resp effort
Hb >=70g/L
Mental status awake & alert or easily rousable
46
:) What are the three areas of respiratory function in which pts undergoing pulmonary resection should have preoperative assessment?
1. lung mechanical function
2. pulmonary parenchymal function
3. cardiopulmonary reserve
47
:) which surgical approach reduces risk respiratory complications for pulmonary resection in patients with underlying lung disease?
VATS
48
what are the criteria for patients to be extubated in OT following pulmonary resection, provided they have adequate predicted postop respiratory function?
alert
warm
comfortable
49
which interventions reduce the incidence of respiratory complications in high-risk patients undergoing thoracic surgery?
smoking cessation
physiotherapy
thoracic epidural analgesia
50
what's the best predictor of post-thoracotamy outcome in the elderly patient?
to which complications are they particularly vulnerable?
preoperative exercise capacity
cardiac arrhythmias & other cardiac complications
51
is hypoxaemia common with OLV?
not with IV anaesthetic or volatile <=1MAC
52
What may contribute to lung injury on OLV?
High TVs (10mL/kg)
53
What’s the underlying principle for management of a pt with bronchopleural fistula?
Secure lung isolation before PPV & positioning for surgery
54
what factors consider when making anaesthetic plan for anterior or superior mediastinal mass?
PTs symptoms, preop CT, echo findings. Don’t burn your bridges
55
what’s an alternative analgesic strategy to thoracic epidural?
Continuous paravertebral with multimodal analgesia- while Tx epidural has been shown to consistently decrease post-thoracotomy resp complications in high-risk patients, continuous PVB is a reasonable alternative, comparable analgesia with fewer side effects & lower rate of block failure (refs 2 & 79 in Miller ch 53)
56
what is the difference between “resectable” and “operable”?
Resectable= disease that’s local or loco-regional in scope
Operable= patient, someone who can tolerate the proposed procedure with acceptable risk
57
what’s the major cause of perioperative morbidity & mortality in thoracic surgical population?
Respiratory complications- atelectasis, pneumonia, respiratory failure- in 15-20% of patients.
58
what baseline test should all pts undergoing pulmonary resection have?
Simple spirometry
59
:) what are the 3 elements of respiratory function to be assessed pre-operatively?
respiratory mechanics
gas exchange (parenchymal function)
cardiopulmonary interactions (exercise capacity)
60
:) what are some tests of respiratory mechanics that correlate with post-thoracotomy outcome?
FEV1
FVC
maximal voluntary ventilation (MVV)- in the normal subject, this value (the maximum MV the subject can maintain for 12-15secs), is about 15-20x the resting MV
RV/TLC ratio (higher suggests worse airflow obstruction)
61
:) to what are predicted volumes from spirometry corrected?
age
sex
height
62
:) what's the most valid single test for predicting post-thoracotomy respiratory complications?
post-op predicted FEV1 % = ( pre-op FEV1 (%) ) x ( 1 - %functional tissue removed / 100 )
63
:) what's the ppoFEV1% at which a patient is at low & high risk of post-resection respiratory complications?
>40% low risk
30-40% moderate risk
patients with ppoFEV1 <30% are at high risk
64
:) what's the most useful test of gas exchange capacity?
DLCO, correlates with functioning surface area of alveolar-capillary interface
65
:) how is calculating the ppoDLCO useful? how to calculate it? by what may the DLCO be negatively effected?
a value of <40% correlates with increased respiratory & cardiac complications
it is, to a large degree, independent of FEV1
ppoDLCO = pre-op DLCO x (1-%functional lung removed/100)
may be negatively impacted by pre-op chemo
66
:) what are the absolute cutoffs of pre-op FEV1 or DLCO that have unacceptably high periop mortality rate?
20%, considered absolute minimum value compatible with a successful outcome. Pts with homogenous emphysema also have very poor outcome.
67
:) how many METs does sitting quietly require?
1, 3.5mL/kg/min
68
:) how much is a flight of stairs?
3m (20 feet)
69
:) what's the most valid simple exercise test & what does it involve?
6MWT, maximal distance a pt can walk in 6 mins, simple, just need markers & stopwatch.
shows excellent correlation with VO2 max.
69
:) what's the most valid simple exercise test & what does it involve?
6MWT, maximal distance a pt can walk in 6 mins, simple, just need markers & stopwatch.
shows excellent correlation with VO2 max.
70
How to calculate VO2max from 6MWT?
Divide total distance (m)/30, ie. 450m distance is VO2 max of 15mL/kg/min.
71
What are other tests of functional capacity, aside from the 6MWT?
Incremental shuttle walking (walk at a gradually increased rate between 2 markers 10m apart, total distance <250m correlates with VO2max of <10mL/kg/min)
Exercise-oximetry: decrease in blood SpO2 >4% during exercise are at increased risk
The gold standard= cardiopulmonary exercise testing
72
What laboratory value is the most useful predictor of post-thoracotomy outcome?
VO2 max of 15mL/kg/min (maximal O2 consumption during aerobic exercise)
If pre-op VO2 max is <15mL/kg/min, high risk of M&M
If pre-op VO2 max is <10mL/kg/min (35% predicted), risk is very high
Very few patients with VO2max >20mL/kg/min (75% predicted) have respiratory complications
73
What echocardiographic abnormality may develop after pulmonary resection?
Right ventricular dysfunction, which appears to be in proportion to the amount of functioning pulmonary vascular bed removed.
Tends to be more evident with exercise vs rest, there is the absence of the normal decrease in PVR usually seen with exertion- there’s instead elevated PVR & limitation of CO.
74
For which patients should ventilation perfusion scintigraphy be considered? Is it useful to predict post lobectomy function?
For pts having a pneumonectomy & pre-op FEV1 or DLCO <80%, since if the lung to be resected has minimal function the prediction of ppoFEV1 or DLCO can be adjusted accordingly
Not useful for predicting post-lobectomy function
75
What’s the ppoFEV1 threshold at which a patient is considered high risk for a lobectomy via VATs? Thoracotomy? (ppoDLCO threshold for open procedures?) What is the main implication of a patient being at increased risk?
30%
40% for thoracotomy (there's a threshold ppoDLCO of 60% for open procedures below which the incidence of respiratory complications much higher)
Extubation plan.
If a pt has ppoFEV1 >40%, the pt can be extubated in OT provided alert warm and comfortable.
If the ppoFEV1 is >30% and the exercise tolerance & lung parenchymal function exceed the increased-risk thresholds, can extubate in OT depending on other medical conditions.
If the pt has ppoFEV1 20-30%, consider their cardioresp & parenchymal function, presence of Tx epidural & whether VATS or open when deciding re: timing of extubation.
76
What are the % risks of 30-day MACE (death, MI, cardiac arrest) with each of the Lee's RCRI categories?
0=3.9%
1=6%
2=10.1%
>=3=15%
77
What's considered high, intermediate & low perioperative cardiac risk surgery?
high >5%
intermediate 1-5%
low <1%
risk of perioperative adverse cardiac event (death or non-fatal MI)
78
in which patients is noninvasive cardiac testing indicated?
those with major (unstable angina, recent MI, severe valvular disease, decamp CCF, significant arrhythmia) and intermediate (previous CCF, diabetes, remote infarction, stable angina) predictors of myocardial risk
79
what's removed in an extra pleural pneumonectomy?
diseased lung, part of pericardium, part of diaphragm & part of parietal pleura
80
what's a common cardiac complication following pulmonary resection surgery? what pt/surg factors increase risk? what are some physiological factors increasing risk?
arrhythmias, particularly AF
higher with greater extent of resection, intrapericardial dissection, intraop blood loss, higher pt age
extrapleural pneumonectomy particularly high risk
incr pulmonary vascular resistance (lung resection, atelectasis/hypoxaemia)
increased SNS stimulation & O2 requirements (maximal postop D2 when pts more mobile)
81
which group of pts are more resistant to pharmacologic-induced HR control when they develop post-thoracotomy AF?
COPD
82
which drug is the most useful for post-thoracotomy arrhythmia prophylaxis? why not B blocker? what are the american thoracic society drug recommendations for postop AF prevention in Tx surgery?
diltiazem
B blockers may be the most effective but concern about use in pts with reactive airways disease
continue B blockers if on them. all pts to have magnesium if low or suspect low total body stores.
high risk pts (eg anterior mediastinal mass, lobectomy, pneumonectomy & esophagectomy) get diltiazem if not on a B blocker & if preserved cardiac function. consider amiodarone & statins.
83
what's the pathophysiology of hypoxaemia during one-lung ventilation for a pt with CCF or cardiomyopathy? how to manage?
OLV= obligatory 20-30% shunt through non-ventilated lung (it's not > this, due to surgical manipulation to atelectatic lung, lateral positioning (incr perfusion to dependent lung), HPV,
if baseline CO decreased, the fall in SmvO2 --> exaggerated fall in PaO2
monitor SmvO2 & may need inotropes to support CO.
84
does ketamine exacerbate pulmonary hypertension?
no, not according to Miller :)
85
other pearls miller adds to the haemodynamic goals for pulm HTN?
avoid hypotensive & vasodilating anaesthetic agents wherever possible
use pulmonary vasodilators (NO, prostacyclin) in preference to IV vasodilators where possible
ketamine does not exacerbate pulmonary HTN
monitor CO
if considering a thoracic epidural, titrate cautiously with low dose LA & inotropes or vasopressors, since sympathectomy may impair tonic cardiac SNS innervation (important for haemodynamic stability in pulm HTN due to lung disease)
86
what doses of NO & prostacyclin (inhaled) can be used for severe pulm HTN?
inhaled NO 10-40ppm
nebulised prostacyclin 50ng/kg/min
87
what's a benefit of paravertebral vs thoracic epidural for thoracotomy analgesia?
better haemodynamic stability with PVB
88
What's the minimum cardiac investigation that should be undertaken in a >70yo pt having a thoracic procedure?
trans thoracic echo to Ix pulmonary HTN
89
what's a useful pre-op test in a pt with COPD awaiting thoracotomy? why do pts (even CO2 retainers) still need supplemental oxygen?
ABG to see baseline PaCO2
to avoid hypoxaemia with the postop fall in FRC
90
what's the only therapy that increases long-term survival & decreases R) heart strain in COPD?
home oxygen
91
what's the criteria for home O2 in COPD?
resting PaO2 of <55mmHg & decreases to <44mmHg with exercise (pts with COPD don't increase their RV EF with exercise as in normal patients)
92
what happens to the pts PFTs when bull occupy >50% of the hemithorax in COPD? what are considerations with ventilation in pts with bullae?
findings of restrictive as well as obstructive disease
during spont vent there's slightly -ve pressure in the bull but then PPV used, pressure in a bulla becomes +ve & it'll expand, risk rupturing & causing tension PTx & bronchopleural fistula. Keep airway pressures low & ensure adequate expertise & equipment available to insert a chest drain & isolate lung if necessary.
93
what's a risk for patients with severe airflow limitation?
severe haemodynamic collapse with PPV due to dynamic hyperinflation of lungs
94
what feature on ICU ventilators allows measurement of auto-PEEP?
end-exp flow interruption
95
what 4 treatable complications of COPD must be assessed & optimised at pre-thoracotomy assessment?
bronchospasm (if pt poorly controlled on beta agonist & anticholinergic, consider trial of corticosteroids)
pulmonary oedema
atelectasis
respiratory tract infections
96
what's the benefit of pre-op physiotherapy for pts with COPD?
fewer postop pulmonary complications
cough, DB, incentive spirometry, PEEP, CPAP are the options, none is proven superior, improvements if done for >1/12 prep (so less feasible prior to OT for resectable malignancy).
97
for how long should smoking be ceased before thoracic surgery to reduce risk pulmonary complications? how soon after smoking cessation do carboxyHb concentrations stop? what type of smoking cessation interventions are most successful?
4 weeks
12 hrs
intensive smoking cessation interventions
98
what are some features of squamous cell carcinoma (NSCLC)?
strongly linked to cigarette smoking
tend to grow large in size & metastasise later than others
symptoms tend to be due to local effects of the large tumour eg. haemoptysis, obstructive pneumonia, SVC syndrome
hypercalcaemia may be associated with squamous cell carcinomas due to parathyroid-like factor
99
what are some features of adenocarcinoma?
most common NSCLC
tend to be peripheral & metastasise early esp to brain, bones, liver, adrenals
almost all pancoast tumors (at apex of lung, can cause horner's syndrome, brachial plexus, RLN) are adenocarcinomas
can be ass'd with paraneoplastic metabolic factors eg. growth hormone & corticotropin, may be associated with hypertrophic pulmonary osteoarthropathy.
bronchioalveolar carcinoma isn't related to cig smoking, low potential to spread outside of the lungs so may be treated with lung transplantation.
100
what are some features of large-cell undifferentiated carcinoma?
uncommon
often large caveatting peripheral tumor
rapid growth, widespread mets
101
what are some features of small-cell lung Ca?
neuroendocrine in origin
usually central lesions
usually a medical vs surgical disease, considered metastatic on presentation
treatment of limited stage SCLC with chemo, aggressive radiotherapy
paraneoplastic syndromes common eg. hyponatremia (SIADH), ectopic ACTH--> hypercortisolism (Cushing syndrome). rare Eaton-Lambert myasthenia syndrome (impaired release of ACh from nerve terminals)- proximal LL weakness & fatiguability what may temporarily improve with exercise. Dx by EMG. similar to MG wrt very sensitive to NDMR & respond poorly to anticholinesterase reversal agents. There may be subclinical involvement of diaphragm & rest mm.
102
what are some features of small-cell lung Ca?
neuroendocrine in origin
usually central lesions
usually a medical vs surgical disease, considered metastatic on presentation
treatment of limited stage SCLC with chemo, aggressive radiotherapy
paraneoplastic syndromes common eg. hyponatremia (SIADH), ectopic ACTH--> hypercortisolism (Cushing syndrome). rare Eaton-Lambert myasthenia syndrome (impaired release of ACh from nerve terminals)- proximal LL weakness & fatiguability what may temporarily improve with exercise. Dx by EMG. similar to MG wrt very sensitive to NDMR & respond poorly to anticholinesterase reversal agents. There may be subclinical involvement of diaphragm & rest mm.
103
what are some features of carcinoid lung tumours?
often proximal, endobronchial, may present with bronchial obstruction & distal pneumonia
often highly vascular
no association with smoking
high 5-year survival following resection of typical carcinoid tumours (90%)
systemic mets rare
atypical carcinoid tumours more aggressive & may metastasise
carcinoid syndrome (due to ectopic synthesis of vasoactive mediators) is rare since they are usually metabolised by the liver; more often seen with carcinoid tumors of gut origin that met to the liver.
carcinoid crisis may occur- be prepared with octreotide
104
how do pts with pleural tumours malignant pleural mesothelioma often present?
how often managed?
disease association?
dyspnoea on exertion from pleural effusion
may have symptomatic improvement with thoracocentesis but pleural biopsy by VATs= most efficient way to obtain diagnosis, often receive talc pleurodesis during the same anaesthetic to receive the effusion
strongly associated with asbestos exposure
105
what are considerations for assessment of lung cancer pts?
4M's:
metastases: esp brain, bone, liver, adrenal
mediations: bleomycin pulm toxicity (bleomycin used for mets from germ cell tumours); association btwn prev bleomycin therapy & pulmonary toxicity with high FiO2 is well-known but the safe doses & safe period after exposure unknown so safest= use lowest FiO2 consistent w pt safety & closely monitor oximetry, doxorubicin cardiotoxicity, cisplatin renal toxicity (avoid postop NSIADs)
mass effects: obstructive pneumonia, lung abscess, SVC syndrome, tracheobraoncial distortion, pan coast, RLN or phrenic paresis, chest wall or mediastinal extension
metabolic effects: eaton-lambert, hypercalcemia, hyponatremia, cushing syndrome
106
Before neuraxial catheter placement does ASRA recommend for prophylactic or therapeutic LMWH?
for prophylactic LMWH, 12 hrs after
24hrs after therapeutic LMWH
107
what particular pearls does miller have for the pre-anaes Ax of thoracic pts?
all: Ax functional capacity, spirometry, discuss postop analgesia, smoking cessation
if ppoFEV1 or DLCO <60%, exercise test
Ca: 4M's
COPD: ABG, physic, bronchodilators
incr renal risk (prep HTN, ARBs, open procedures, use of starch): measure Cr, BUN
108
which 3 things do miller recommend for the final preanaes Ax for Tx surgery?
1. review of initial Ax & test results
2. anticipate potential for difficult lung isolation (CXR, CT chest)
3. assess risk of desaturation during OLV
109
What should be reviewed pre-op to assist with determining if likely difficult lung isolation?
CXR, CT chest (eg. for saber-sheath trachea or extrinsic compression or intraluminal obstruction).
110
what factors correlate with increased risk of desaturation during OLV?
what are the most useful prophylactic measures vs desaturation during OLV that could be employed for high-risk pts?
anaesthetic: poor SpO2 on 2-lung ventilation, esp in lateral position. Lower PaO2 on two-lung ventilation (eg. 200mmHg vs 400mmHg).
surgical: R)-sided thoracotomy, since the L) lung is 10% smaller than the R), there's less shunt when the L) lung collapsed (mean PaO2 70mmHg higher in L) vs R) thoracotomy).
supine position during OLV
patient: normal PFTs pre-op, restrictive lung disease; patients with more severe airflow limitation on pre-op spirometry tend to have better PaO2 during OLV than pts with normal spirometry. High % V or Q to the operative lung on prep V/Q scan.
CPAP (2-5cmH2O or O2) to the non ventilated lung, PEEP to dependent lung
111
what happens to the PaCO2-EtCO2 gradient during OLV? implications?
increases, so PetCO2 is a less reliable indicator of PaCO2.
CALHN payroll number 3025831
112
features of a specially designed SLT for endobronchial intubation? how lung isolate in infants/v small chn?
longer, shorter cuff, can advance into mainstream bronchus under fiberoptic guidance
uncured paed ETT advanced into mainstream bronchus under guidance with infant bronchoscope
113
how should the position of a DLT be confirmed?
auscultation and bronchoscopy after placement & repositioning.
with the FOB through tracheal lumen, ensure the endobronchial portion in correct main bronchus, no bronchial cuff herniation over carina after inflation (cuff should sit 5mm below tracheal carina for L) bronchus), identify takeoff of the R) UL bronchus (the only structure in tracheobronchial tree w 3 orifices. then FOB through endobronchial lumen to check tube potency & margin of safety, visualise orifices of L) upper & lower lobes.
114
how do longitudinal elastic bundles assist with bronchoscope orientation?
run down posterior tracheal & mainstem bronchial walls, then the L) lower lobe (useful landmark to distinguish from L) UL)
115
which of the bronchial blockers have murphy's eyes?
cohen
the arndt does in the size 9Fr
116
relevant to airway difficulty with pts requiring OLV, what proportion of pts with primary lung carcinoma also have carcinoma of the pharynx?
5-8%, usually in the epiglottic area, many have had previous radiation therapy on neck or prev airway surgery
117
airway strategies for patients with difficult airway requiring OLV?
AFOI nasal or oral with SLT then pass bronchial blocker
could alternatively do a SLT then tube exchange
118
what sizes should airway exchange catheter be for exchange from SLT to DLT?
at least 83cm long
14Fr for size 39 & 41 Fr DLTs
11Fr exchange catheter for size 35 & 37 Fr DLTs
119
how deep should an airway exchange catheter be inserted to avoid damage to trachea/bronchi?
No deeper than 24cm @ lips
sniffing position helps
video laryngoscope to guide the 2nd tube, assistant holding scope
confirm with auscultation & bronchoscopy
if doing a SLT for DLT tube exchange, test the SLT, AEC & DLT combo in vitro
120
In which thoracic cases may lateral induction be considered?
Unilateral bronchiectasis or haemoptysis (diseased lung down) until lung isolation achieved, then diseased lung to nondependent side.
121
How to limit ETT displacement?
Move head, neck, ETT “en bloc” with TL spine
122
What are the 2 main types of brachial plexus injures in lateral decubitus & risks for these?
Compression injuries- dependent arm directly under thorax, pressure clavicle, caudal migration of Tx padding
Stretch injuries- lat flexion of C-spine, excessive abduction of arm >90deg, rotation of torso & traction on fixed arm
123
Traction injury to which nerve, due to excessive contralateral neck flexion in lateral postion or arm circumduction, may cause pain @ posterior/lateral aspect of shoulder?
Suprascapular nerve
124
What are principles of fluid management for lung resection?
Judicious- risk exacerbating shunt & pulmonary oedema, particularly during prolonged surgery, vital to avoid since dependent lung responsible for all the gas exchange. Total +ve fluid balance in the first 24hrs periop should not exceed 20mL/kg for pulmonary resection. Average adult: no >3L crystalloid. Do not need to titrate to UO >0.5mL/kg/hr. inotropes preferable to fluid overload to incr tissue perfusion postop.
125
Why is normotheramia particularly important during Tx surgery?
HPV is inhibited during hypothermia (as are most of the body’s physiological functions)
126
What are some principles for avoiding bronchospasm (particularly important for Tx surgery as reactive airways disease common)?
limit airway manipulation while in light plane of anaesthesia
Use BD anaesthetic
Avoid histamine-releasing drugs
Props or ketamine diminish bronchospasm, sevo the most potent BD of the volatiles but prop TIVA or volatile fine
127
Considerations for the fact that many pts for Tx surgery have coexisting CAD?
Myocardial O2 supply/demand (preserve DBP, Hb, avoid tachy, ensure comprehensive analgesia)
128
How to optimise rate of collapse of operative lung for VATs?
Pre-oxygenate with 100% O2 as nitrogen lower solubility will delay collapse (esp if pts have emphysema & decr elastic lung recoil)- the dependent lung will develop atelectasis so recruit after OLV.
129
What SpO2 acceptable during OLV?
No universally accepted figure, >=90% commonly accepted, high 80s briefly accepted for pts sans sig comorbidity.
130
What am I really trying to do to achieve normoxia during OLV?
Maximise PVR in the nonventilated lung while minimising it in the ventilated lung; HPV promoted blood flow to the ventilated lung, PPV tends to do the opposite, surgical manipulation & cardiac output changes have variable effects on proportional flow to ventilated lung. Aim to keep the ventilated lung as close as possible to FRC as at high or low volumes, incr PVR (hyperbolic relationship). Aim to keep the nonventilated lung collapsed.
131
How much does HPV contribute to blood flow redistribution?
It can decr blood flow to nonventilated lung by 50%
132
What are the 2 phases of HPV?
Initial immediate & plateaus after 20-30mins, 2nd phase begins after 40 mins & plateaus @ 2hrs
133
What effect do vasodilators have on HPV?
Worsen it- vasodilators tend to cause deterioration in PaO2 during OLV
134
How may Tx epidural impact HPV?
Not directly, but may indirectly impact oxygenation if hypotension & reduced CO occur
135
What’s better wrt HPV? TIVA or volatile?
No clinical benefit on oxygenation using one over the other if the VA is <=1MAC, although the modern volatiles do slightly impair HPV it’s to a less extent that prev volatiles & is not clinically sig (reduce HPV by 20% @ 1 MAC< equivalent to reducing total AV shunt 4% which is negligible in most situations. On the flipside, there may be less pro-inflammatory cytokines & lower incidence of postop pulm complications & lower 1-year mortality with volatiles.
136
Why avoid N2O during thoracic anaesthesia?
Ass’d with more atelectasis of dependent lung, increases PAP in pts with pulm HTN, impairs HPV, may expand air-filled spaces.
137
Why is it so vital to maintain good CO during OLV?
Even with optimal anaesthetic management there’s a shunt of 20-30% during OLV, so vital to maintain CO but not supranormal (excess CO increases shunt but also SvO2 but there’s a ceiling effect to SvO2 incr so ultimately that may cause hypoxaemia, low CO reduces both shunt & SvO2 which leads to hypoxaemia).
138
Does addition of PEEP improve PaO2 during OLV?
Depends on the patient. Patients with COPD & auto-PEEP will tend to be pushed further away from the lower inflection point of FRC hence PaO2 may suffer, while pts with normal elastic recoil or restrictive lung disease (high recoil) may be pushed towards FRC inflection point & gas exchange benefits from PEEP.
139
What’s an optimal starting strategy for ventilation of a pt for OLV (cognisant that it needs to be titrated based on the pt?)
5-6mL/kg IBW TVs, PEEP 5cmH2), Pawpeak no >35cmH20 (Pplat approx. 25cmH2O). lateral positioning will require approx. a 20% increase in MV to maintain PaCO2- PetCO2 is a less reliable monitor of PaCO2 during OLV as the gradient becomes larger.
140
Pros/cons of VCV or PCV?
PCV ass’d with lower peak airway pressures but not improved oxygenation. PCV does avoid sudden increases in peak airway pressure with surgical manipulation of the chest which is of benefit if a bronchial blocker or if at risk for lung injury (eg. After pneumonectomy or lung transplant) but given the frequent manipulation, check volumes achieved with PCV as it may be suboptimal.
141
why do pts with R) thoracotomies tend to have larger shunt & lower PaO2 than pts with L)?
R) lung is larger & 10% better perfused than the L)
142
what's the general pattern of SpO2 during OLV?
fall in arterial oxygenation, nadir 20 mins then stabilise & may rise with the increase in HPV over the next 2hrs.
143
What is a caveat to using nebulised epoprostenol?
Glycine can build up in the HME filter, increasing airflow resistance. Need to change HME filter every hour when nebulised epoprostenol used.
144
Why does desaturation occur more commonly for the 2nd lung for bilateral pulmonary surgery?
The first lung is impaired from mechanical trauma and HPV offset may be delayed after reinflation of the first lung collapsed. Therefore for bilat procedures, operate fist on the lung that has better gas exchange (usually the R) lung since larger & higher proportion of blood flow)
145
SS_TS 1.6: Discuss the assessment of patients with mediastinal masses for surgical procedures including the assessment of severity of vascular and respiratory obstruction and the implications for anaesthesia management
-What’s the main consideration/concern with pts with mediastinal masses?
-What are some other procedure-related risks?
-Describe preoperative assessment of patients with mediastinal masses, rationale & planning based on findings
-Discuss intraoperative planning for mediastinal masses?
The risk of airway compression or compression of vital vasculature (IVC, PA) due to mass effect with induction of anaesthesia, which obliterates the awake patient's compensatory mechanisms (compression of airway structures & great vessels with sitting to supine, loss of airway patency after administration of NMBAs, increased Pit with decreased VR to heart during transition from spont -ve pressure vent to controlled PPV, arterial & venodilation & myocardial depression caused by administration of anaesthetic induction agents)
surgical manipulation & resection of mass incl. compression of airway structures/great vessels, risk to airway continuity or patency due to injury to trachea or other airway structures
major haemorrhage due to injury to structures adherent to or proximate to the mass
History:
-Nature & history of the mass, predominantly to assess risk of AIRWAY or RESPIRATORY compromise +/- HAEMODYNAMIC INSTABILITY due to mass effect on airways & lungs or major cardiovascular structures which may occur with induction (loss of awake/upright compensatory mechanisms, loss of muscle tone, incr Pit with spont to PPV)
-where is it?
-how large & rapidly growing is it?
-what is it thought to be? (impacts how likely it is to be adherent, ass'd w mets, secreting)
-are there symptoms related to effects of the mass on adjacent intrathoracic organs?
-SVC obstruction of progressive grades: facial oedema or plethora, Pemberton's +ve (eg. retrosternal thyroid extension or lung carcinoma, lymphoma, thymoma or some aortic aneurysms ("nutcracker" effect where medial clavicles impinge major venous structures within a narrowed Tx inlet against a relatively fixed & enlarged mass)), UL oedema, hoarseness (vocal cord oedema), dysphagia or cough, visual disturbances (ocular oedema), dizziness/headache from cerebral oedema, syncope or near-syncope after bending, stridor (significant laryngeal oedema), significant haemodynamic compromise such as hypoT or syncope without trigger. Hypotension may also raise possibility of cardiac compression or tamponade.
-can they lie flat (and for how long/are there positional changes that alleviate this? Haemoptysis, chest pain, dyspnoea?)
-Are there systemic symptoms due to paraneoplastic syndromes (eg. thymic mass secreting anti ACh receptor antibodies--> MG, parathyroid adenoma secreting PTH (primary hyperparathyroidism)--> hyperCa++)
-Has the patient completed chemo or radiotherapy to reduce mass effect/optimise successful resection? if so, adverse effects of chemo & impacts of radiotherapy on anaesthesia (dry mouth/airway swelling, airway friability, mucositis, oesophagitis and dysphagia/reduced PO intake/dehydration are considerations, as is scarring fibrosis of thoracic connective tissue potentially resulting in need for high airway pressures (peak pressure >30mmHg) during PPV)
-Other general & anaesthetic Hx & systems review, functional status
Examination:
-walking into waiting room, vital signs, signs of work of breathing/preferred postures, plethora/cyanosis/oedema/venous engorgement
-auscultating lungs and heart
-pedal oedema/other signs of right heart failure
Investigations:
-CT, MRI +/- radio nucleotide studies- imaging to assess relationship of mediastinal mass to airway, lungs, heart & major blood vessels (*in an awake pt so the imaging may not predict changes after induction)
-echo
-pulmonary function tests have minimal utility (poor correlation with airway obstruction)
-exercise tolerance- stress test or quantify w METs DASI
-ECG
Planning:
-multi-D discussion with surgeons; plan OT to be @ tertiary centre, daylight hours, senior operators, ICU aware/present
-if the mass is associated with high likelihood of cardiovascular collapse or complete tracheal obstruction during induction or surgical intervention, may employ cardiopulmonary bypass (having them on standby likely futile as time to cannulate major vessels is at least 10 mins) or ECMO.
-IV access & art line monitoring plan (pre-induction, location particularly if SVC obstruction or if risk compression of arterial supply to either limb)
-blood products- if large mass in critical location, d/w surgeons EBL
-regional techniques pre-incision- approach & US, haemodynamic considerations (may just place opioid pre-incision)
Discuss plan & risks w pt, verbal informed consent
Pre-team brief re: surgical & anaesthetic concerns, contingency plans
Eg. if CPB or ECMO are initiated pre-induction, anaesthetist must be ready to sedate for cannulation, heparin administration prior to CPB, administration of vasoactive agents & protamine during & after CPB weaning- if this is planned, do a femoral CVC & art line, sedate with midaz or ketamine for cannulation, heparin prior to partial CPB, GA induction once CPB established, if haemodynamic instability then initiate full CPB.
Monitoring: appropriate site & size (considering actual or potential vessel obstruction)
Assistant: skilled, briefed
Drugs:
Sedation for lines & regional
LA +/- adjunct for regional
Induction agents with minimal or favourable effects on haemodynamics if IV induction (eg. Ketamine, may consider spont breathing volatile induction for anterior mediastinal mass)
Preventive/opioid sparing analgesics (ketamine, paracetamol, parecoxib, dexamethasone)
Adequate volume to maintain CVP & arterial BP
Vasoactive infusions
Equipment: for CVC, art line (bilateral if risk vascular occlusion in an upper extremity, LL if risk of vascular occlusion both ULs), warming, airway equipment choice depends on the mass, eg: consider awake or asleep (eg spont breathing) bronchoscopy, reinforced ETT, longer microlaryngoscopy tube if distal trachea compressed, DLT if lung isolation needed, ensure rigid bronchoscopy available if loss of airway patency is possible. TOE if ant mediastinal mass compressing heart or major vessels or is attached to myocardium or pericardium (provided no contraindication eg. Mass impacting oesophagus, Hx UGI bleeding or other severe oesophageal or gastric disorder).
Induction:
Surgeon present- if loss of airway patency during induction & unable to advance flexible bronch or ETT, surgeon could use rigid bronchoscopy w JV. other emergency alternatives are repositioning the pt (if a "position of safety" identified pre-op)
Plan depends on (for anterior mediastinal masses):
-risk of airway & respiratory compromise (obstructive or restrictive)- "don't burn your bridges" if airway safety uncertain
if "unsafe” (ie. severely symptomatic, CT tracheal/bronchial diameter <50% of normal irrespective of symptoms), options may be awake LA biopsy if diagnostic.
loss of the awake pts compensatory mechanisms, relaxation of bronchial smooth muscle & reduced lung volumes, effect of NMBAs (loss of diaphragm caudal movement) all reduce the normal -ve transpleural pressure gradient that usually holds airways patent; transition from spont vent to controlled PPV also a time of risk (spont breathing induction technique, may maintain spont breathing after intubation if pt becomes haemodynamically unstable since it avoids the reduction in preload with PPV). step-by-step induction w careful monitoring. only give muscle relaxant once know PPV will be possible (ie gently bag manually first).
-risk of cardiovascular collapse
Pre-O2 in the pts preferred position which has least symptoms (may be upright or lat decubitus)
Consider AFOI with spont breathing eg. If vocal cord oedema or other symptoms due to SVC syndrome
Maintenance:
Continuously monitor airway patency, oxygenation & ventilation- communicate with surgeon
Emergence:
Consider a final bronchoscopy/suction after adherent mass removed, during the transition from PPV to spont NPV- if a DLT was used, this may not be possible until after extubation (extubate deep, place a SGA & examine with flexi bronch)
Smooth, coughless particularly if significant tracheomalacia or tracheobronchial tree disruption since coughing incr airway pressure & risk compromising any anastomoses or cause bleeding/airway leak, eg. Remi 0.1-0.3mcg/kg/min, lignocaine 1mg/kg.
Postop:
Disposition HDU, MAY be intubated if pt or surgical factors prohibiting extubation- if DLT, replace it with a SLT using a tube exchanger prior to ICU.
If extubated in recovery, mindful of complications postop (airway compromise (oedema, nerve damage, tracheobronchial obstruction), haemorrhage); keep rigid bronch, diff airway trolley & surgeons on hand until know recovered
146
SS_VS 1.4: Discuss the surgical requirements and implications for anaesthetic management of patients having elective surgery for thoracoscopic sympathectomy
often ASA2, young with hyperhidrosis, also can be done on multicomorbid pt w refractory angina
GA with or without DLT (surgeons will often use CO2 to have some long collapse to access the sympathetic chain; cauterise or ligate or LA).
Large IVC, only needs IAL if significant co-morbidities (and beachchair type position with arms up so care with position & MAP to defend cerebral perfusion. Uni or biportal. intercostal block by surgeons, often a day procedure, use multimodal analgesia.
Minimal postop pain (multimodal), postop may have PTx or compensatory hyperhidrosis below level of correction.
147
predictors of desat on OLV?
high (normal) FEV1
supine OLV
L)-sided OLV (smaller left lung)
low pO2 prior to OLV
148
Superior mediastinum?
divided by line from sternal angle to inf border T4
inferior mediastinum ant/middle/post by heart & pericardium.
149
distinction eaton-lambert (myaesthenic syndrome) from MG?
ELS is a proximal myopathy ass'd w small cell carcinoma. reductions in ACh from presynaptic motor n terminals. incr sensitivity to ALL NMBAs. muscle weakness improves w exercise, no improvement w acetyl cholinesterase inhibitor.
150
what size PTx on cxr conservative Mx?
<20% if not compromised
151
Pneumothorax:
Pneumothorax:
Primary- no known underlying disease, generally bullae
Secondary- underlying condition eg. COPD, asthma, CF, marfans, ARDS, pneumonia, trauma
Iatrogenic- Pneumoperitoneum, thoracoscopy, PPV, CVC, nerve blocks, surgery lower neck
Awake spot breathing pts pleuritic chest pain & dyspnoea. If underlying lung disease, severe dyspnoea & sig hypoxaemia.
ABGs: incr A-a gradient, acute Resp alkalosis.
In critical illness, deterioration in rep & CV variables, physical exam.
XR/US; small (<15%) often normal physical findings aside from mild tachycardia (the commonest finding)
larger: dear chest expansion, hyper resonant percussion, tracheal shift, decreased or absent breath sounds on affected side.
Tension: systemic hypotension, central cyanosis. Ventilator shows decreased TVs & compliance. High CVP. Late= distended neck veins, displaced apex beat.
Upright XR: radiolucent thoracic air w absent lung markings btwn shrunken lung & parietal pleura. PA XR is poor method of quantifying size of PTx, usually underestimates it.
supine XR: deep sulcus sign, Lucent upper quadrants of abdomen, sharp superior surface of duaphragm.
Chronic lung conditions w pleural adhesions may restrict lung collapse.
Tension: mediastinal shift
US sens 95% & spec 100% cf CT as standard.
CT indicated to differentiate PTx from bullies disease, to Dx supine PTx, if XR obscured by emphysema. Allow Dx of other pleural/lung pathologies.
It’s the gold standard for PTx imaging but impractical/unsafe in critically ill, impractical for repeated imaging.
Management:
Small primary spont PTx in spont breathing asymptomatic pts: conservative, adding high FiO2 may speed resolution by reducing partial pressure nitrogen in pulmonary capillaries. Incr partial pressure for reabsorption air pleural cavity—> pulmonary capillaries, rate is 1.5% of the volume of the hemithorax/24hrs.
Must treat symptomatic pts, those needing PPV or altitude (reduction in Bar may expand a PTx).
Avoid N2O (expands a PTx).
Symptomatic or >3cm or all but the tiniest (<1cm or apical) secondary PTx: Small bore chest drain (large-ore if blood). In “safe space” mid axillary line; away from internal mammary, scarring breast tissue, distant to viscera. Keep in until bubbling ceased & CXR shows lung inflation. If non-resolving or after chemical pleurodesis, high-vol/low-pressure suction (with underwater seal, 10-20cmH2O). If symptoms persist after 10 days, consider foreign body/tumour/mucus plug, CTS R/V for VATs.
Tension: immediate decompression, 14g IVC 2nd ICS MCL, keep in until bubbling on formal UWSD.
Intraop considerations:
airway plan (DLT/BB) for VATs
is chest draining adequtely (bubble, swing)
surgeons present as backup (ready for 2nd ICC)
spont breathing TIVA/volatile or AFOI to maintain -ve PiP until isolated, vs RSI bype with gentle intro of PPV
considerations re: plan/target SpO2 for OLV (reasons desat gen inadequate FiO2, alv hypoven, large shung)
pressure areas
fluids Inot excessive), ABx, vasopressors
LPV
noromotheria & Hb (DO2) & metabolics
152
Pneumonectomy
Highest postop mort of all pulm resections, only consider once all surg options excluded
40% get pulm HTN within 1 yr- important to know R) heart function (RV failure unsuitable for pneumonectomy)
20% resp comp, 10% cardiac complications
peak ischaemia 72hrs postop
Complications due to shunting of whole pulm circ, compromosed gas exchange
Preop Ax:
-often Ca, M's
-Pulm parenchymal function (gas exchange: national emphysema trial ppoDLCO<20% cancel, >40% no probs, 20-40% greyzone
open surgery, traditional ABG cutoffs PaO2<60, PaCO2>45)
-Lung mechanical function:
FEV1 >2L pneumonectomy
>1.5 lobectomy
vent esp FEV1; ppoFEV1 >40%--> OT
*all pts need PFTs; for those where need to distinguish borderline & contribution of lung to be resected, schntigraphy considerd
Cardiopulmonary reserve:
SO, if FEV1 was <2L (pneumo) or <1.5 (lob), and if ppoFEV1 or ppoDLCO were <40, exercise testing.
VO2 max >15mL/kg/min--> OT
<15mL/kg/min, consider other options
all pts having pneumonectomy need TTE
Functional capacity, why liited, consider the implications (eg. COPD or m weakness less likely to improve vs obstructing lesion)
Shuttle walk: 400m correlates w peak O2 consumption >15mL/kg/min
consider if pt able to tolerate the OT if it proceeds & were advanced to a bigger OT, if can withstand the recovery/postop;
generally age >70 & pulm HTN unsuitable (esp R) pneumonectomy, pulm HTN a relative CI
Optimisable factors:
?prehab
manage any infection/secretions
bronchodilators
smoking cessation
diuretics if +ve fluid balance (high mort if pulm oedema during Tx surgery)
Hb/Fe
Plan:
discussion multiD re suitability
consent
ICU bed
Xmatch 2U red cells (ensure G&H)
Intra-op:
Analgesia: painful, posterolat thoracotomy 5th ICS
may excise 5th rib, will have thoracostomy tube postop
or VATs
MMA (incl ketamine), PVB VATs, consider TEA open (but similar pain efficacy, no diff sig comp/LoS/mortality), consider SNS effects of neuraxial
Choice of airway, lung isolation technique (if BB, withdraw before stapling)
Ventilation strategy: 4-6mL/kg, max peep 8-10)
Circulation: careful communication esp when clamp R) or L) main pulm artery to anticipate this & ensure stable CO (entire circulation diverted to one lung, pressure for heart esp if R) lung)
FLUIDS: high mortality if intra-op pulm oedema; balance between restrictiive to limit pulmonary but need adequate perfusion for heart/kidneys; no >2mL/kg/hr for first 24hrs OR prev hours UO + 20mL, UO 0.5mL/kg/hr acceptable, but dynamic Ax
normothermia: hypothermia impairs HPV
Monitoring:
IABP, CVC (may need vasopressors)
IDC & temp probe
TIVA useful as rigid bronch at start of case
Position lateral w table break, pressure areas
VTE prophylaxis
Normothermia
Postop:
awake, warm & comfortable
adequate analgesia for cough, mobility
ongoing invasive monitoring (ICU)
APS
complication surveillance: haemorrhage, pulm odema (>50% mort, more common oafter R) pneumo), bronchopleural fistula (also more common R) pneumo), airway plugging, cardiac arrhythmias- up to 40% get AF
cardiac herniation, mort >50%
dedicated thoracic ward after step down from ICU
incentive spirometry, physiotherapy
*drain care- clamped only check 1 in evry hour for haemorrhage, risk mediastinal shift.
