Thoracics Flashcards
What’s the correct size for a l-sided dlt?
Bronchial tip 1-2mm narrower than L) main bronchus diameter, allowing for the deflated cuff
What size dlt for a <160cm female?
>160cm? <170cm male? >170cm male?
Females <152cm? Males <160cm?
35,37,39,41
Look at ct, consider size 32fr for female, 37 for male
What’s the correct depth for a dlt?
12+(height/10) cm @ teeth EXCEPT in Asian ppl (height not such a good predictor- risk rupture L) mainstem bronchus)
about 27-29cm
How far from the carina does the r) ul bronchus originate?
1.5-2cm
What’s the only structure in the tracheobronchial tree with 3 orifices?
R) UL bronchus ; anterior, apical, posterior
What are the absolute indications for one lung ventilation?
- 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
What are the relative indications for OLV?
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
What are the weaker relative indications for OLV?
To improve surgical access for:
oesophageal surgery
mediastinal mass reduction
middle & lower lobectomy or sub segmental resection
procedures on Tx spine
What are the 3 available techniques for OLV?
DLT
bronchial blocker
Univent tube
single lumen tube advanced into the L) or R) main-stem bronchus (endobronchial tube)
What are the indications for a R)-sided DLT?
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)
Why is L)-sided thoracoscopic surgery an indication for R)-sided DLT?
*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
What should the french scale of the DLT correspond to?
the external diameter of the tracheal segment, in mm, multiplied by 3
What’s the process for confirming position of DLT?
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
What are some problems related to the use of DLTs?
- 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
What french is the cohen blocker? what is the smallest recommended ETT for coaxial use?
9Fr, size 8 ETT
What are some advantages of bronchial blockers?
-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
What are some disadvantages of bronchial blockers?
-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
What are advantages & disadvantages of lung isolation with an ETT advanced into a bronchus?
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
What are the advantages & disadvantages of DLTs?
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
What are the dimensions of the aintree catheter?
56cm, 19Fr
Which size tube fits over an aintree catheter?
size 7
What depth should the AIC NEVER go beyond the lips?
26cm
What’s the best LMA for use with AIC?
proseal
What’s the safest lower limit of SpO2 during OLV?
> =90%
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
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
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.
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
What is the working port of the fibrescope used for?
O2, suction, LA injection
What’s the Chula formula for length of nasal tube?
9+(height/10)cm
To which scenarios is AFOI best suited?
non-emergent approach to expected difficult airway, particularly anticipated difficult intubation, ventilation or unstable C-spine
What’s the level of the carina?
T5, angle of Louis
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
What are the objectives of DLT?
- optimal gas exchange during OLV
- allow operative lung to collapse
- integrity of isolation: no spill over of ventilation, blood, pus
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)
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.
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.
postop priorities pneumonectomy
analgesia (minimise nadir with resp function)
fluid balance
mediastinum position
physiotherapy
avoid atelectasis/infection
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.
What’s an acceptable technique for a pt with difficult airway needing a DLT?
single lumen tube then railroad bronchocath DLT.
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.
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
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.
For which pts with mediastinal masses is a CVC necessary?
Those who may develop airway obstruction +/- haemodynamic compromise from anaes or surgery
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
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
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
:) What are the three areas of respiratory function in which pts undergoing pulmonary resection should have preoperative assessment?
- lung mechanical function
- pulmonary parenchymal function
- cardiopulmonary reserve
:) which surgical approach reduces risk respiratory complications for pulmonary resection in patients with underlying lung disease?
VATS
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
which interventions reduce the incidence of respiratory complications in high-risk patients undergoing thoracic surgery?
smoking cessation
physiotherapy
thoracic epidural analgesia
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
is hypoxaemia common with OLV?
not with IV anaesthetic or volatile <=1MAC
What may contribute to lung injury on OLV?
High TVs (10mL/kg)
What’s the underlying principle for management of a pt with bronchopleural fistula?
Secure lung isolation before PPV & positioning for surgery
what factors consider when making anaesthetic plan for anterior or superior mediastinal mass?
PTs symptoms, preop CT, echo findings. Don’t burn your bridges
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)
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
what’s the major cause of perioperative morbidity & mortality in thoracic surgical population?
Respiratory complications- atelectasis, pneumonia, respiratory failure- in 15-20% of patients.
what baseline test should all pts undergoing pulmonary resection have?
Simple spirometry
:) what are the 3 elements of respiratory function to be assessed pre-operatively?
respiratory mechanics
gas exchange (parenchymal function)
cardiopulmonary interactions (exercise capacity)
:) 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)
