Thoracic Sugery Flashcards
Smoking cessation 2 motns
bronchial secretions increase = risk of complications
however, with advanced lung cancer patients can’t wait 2 months for surgery
What PFTs are needed for thoracic surgery to predict postoperative risk?
PPO FEV1 - calculates current FEV1 multiplied by the fraction of functioning lung
and DLCO
Traditional FEV1 is not enough
DLCO
diffusion capacity
DLCO (diffusion capacity)
measures the lung’s ability to transport gas across the alveolar capillary membrane
pt holds breath of CO for 10 seconds, then exhales. Measure meant of exhaled CO is calculated with predicted values
What DLCO increases complicaion risk?
<60%
Normal DLCO
17-25 mL/min/mmHg
Predicted postoperative product is
FEV1 multipled by DLCO
VO2 max
max O2 consumption during exercise
VO2 low posoperative risk
> 20 mL/kg/min
can climb 5 flights of stairs
VO2 high postperative risk death
<10 mL/kg/min
cannot climb one flight of stairs
V/Q tests postoperative risk (how?)
Radioisotope IV dye shoes perfusion to all areas of lung - calculations can be made to determine pulmonary function once diseased areas are removed
Post operative complications ABGs and SPO2
SpO2 <90% is indicative of post-op complications
PaCO2 is indicative of poor ventilatory function but not post op complications
EKG high postoperative complication risk
RV hypertrophy - low QRS and poor R wave progression
Cancer risk factors
4 M’s (lung damage/poor lung funtion)
mass effects
metabolic effects
metastases
medications
What PPO FEV1 warrants further testing preoperatively?
PPO FEV1 < 40%
What should be checked if PPO FEV1 is < 40%?
DLCO
V/Q scan
VO2 max
High risk candidates FEV1
<2L or <40% of predicted
Oxygen desaturation high risk
> 4% during exercise
Pulmonary artery catheter monitoring will not be accurate if
surgery on the right lung and is collapsed
usually not used
Arterial line placement lateral decubitus
Dependent arm for stabilization
Arterial line placement during medistinoscopy and why
R arm - detects compression of innominate artery - able to identify a decrease in cerebral blood flow
SPO2 monitor placement for mediastinoscopy
R arm - detection of innominate artery compression
Normal lung blood flow distribution in lateral position
60% to dependent lung, 40% to nondependent lung
How does V/Q mismatch occur in lateral decubitus position?
- FRC is reduced during induction
- FRC is further reduced in dependent lung (where perfusion is best) = uneven reduction in FRC–>ventilation increases in nondependent lung
ventilation is not best in dependent lung
V/A mismatch in paralyzed, mechanically ventilated patient
Further reduced FRC (diaphragm no longer counteracting)
ventilation goes to nondependent lung even more, but perfusion still better in dependent lung = even more V/Q mismatch
Open chest and V/Q mismatch
Open chest reduces resistance in ventilation, so it goes even more to nondependent lung.
Mediastinum shifts downward from loss of neg intrapleural pressure in open lung = ventilation of dependent lung decreased even more
Creates the largest V/Q mismatch
How does OLV help V/Q mismatch
Hypoxic Pulmonary Vasoconstriction - lung is deflated and blood flow diverts to areas of higher PAO2 (better ventilated, nondependent lung)
What triggers HPV
alveolar hypoxia
NOT arterial hypoxemia
Where does HPV take place?
ONLY in proximal pulmonary arteries
(in circulation, hypoxemia causes vasodilation)
HPV decreases blood flow during OLV by
50%
In OLV, the blood flow distribution between lungs is
80:20 (instead of 60:40)
What fraction of lung hypoxia causes HPV to yield right ventricular strain?
When 80% of lung is hypoxic, increased PVR causes RV strain and failure
What anesthetic factors/events can redcuce HPV?
- Hypo/hypervolemia
- Too high Vt or PEEP
- inhalation agents >1.5 MAC
- acidosis or alkalosis
- hyOcapnia
- HypOthermia
- vasodilators and vasoconstrictors
Absolute indications for OLV
- isolation from one lung to another (infection or massive hemmorage)
- Control of distribution of ventilation
- Unilateral bronchopulmonary lavage
Relative indications for OLV
Will lung get in the way of surgery? Ideally OLV, but may not be tolerated
Know this list
When should you turn ETT 90 deg for OLV
immediately after advancing through cords. Then remove stylet and advance
Once throught cords and after removing stylet, how far should you advance ETT for OLV?
27-29 cm
Tracheal cuff inflation
5-10mL
bronchial cuff inflation
1-3 mL
Complication of DLT
bronchial rupture from over-inflating cuff
1-3mL max
Complication of Right sided DLT and why
bronchial lumen can obstruct right upper lobe
less distance from carina to right upper lobe (2.5 cm compared to 4-5 cm on left)
consider using left sided DLT unless there is a contraindication
Basic anesthetic considerations in OLV
- <1.5 MAC
- No N2O (increases PVR and traps air)
- avoid long acting NMB (panc)
- frequently monitor NMB fxn and always reverse
Main goal during surgery for anesthesia
Maintain adequate oxygenation while maintaining visualization of lung for the surgeon
Ventilator settings for OLV
- Vt limited to 6mL/kg
- PEEP only 5-10
- Reduce FiO2 - absorptive atelectasis
- avoid hypocapnia (reduces HPV)
- normal ETCO2 (28-32)
Hypoxemia occurance during OLV: what should you do?
- increase FiO2
- check for malposition of tube (listen, bronchoscope)
- differentiate physiologic causes
- recruitment manevuer, CPAP, PEEP to dependent lung (let surgeon know)
- Possible early ligation of PA (if this is in the plan)
- Almitrine to NDL
- NO to dependent lung
Definitive treatment for hypoxemia during OLV
Resume two long ventilation
After lung resection, the operative lung is ______. You should
reinflated and checked for air leaks.
keep PIP < 30-40
Following lung re-expansion _____
deflate bronchial cuff (avoid ischemia to bronchus)
Most effective pain control for thoracic surgery
Thoracic epidural T6-T8
Thoracic epidural analgesia and HPV
does NOT decrease HPV
can use less agent with working epidural
Analgesia considerations (thoracic surgery)
- PCA
- adjuncts (ketamine)
- Thoracic epidural *
- Paravertebral nerve blocks at level of incision plus 1-2 levels above and below
- cryoanalgesia
- intrapleural catheter with LA before closure
Acute lung injury MOA
reperfusion induces inflammatory mediators at alveolar-endothelial barrier causing leakage of fluid
Fluid overload causes
stretching of cappilaries. Disturbs permeability = failure of microvessels
Dysrhymias after thoracotomy
- afib
- SVT
associated with fluids > 2000 mL intraoperatively
Basic categories complicatinos after thoracotomy
- ALI
- dysrhymias
- Low CO
- Increased PVR
- Respiratory complications
- Nerve and spinal cord injuries
- Thoracic duct injury
Which side lobectomy is better tolerated and why
Left is better tolerated because R lung is bigger, has more blood flow and oxygenation
Nerve injuries that can occur during thoracotomy
- Phrenic nerve
- L recurrent laryngeal nerve
- spinal cord
Types of mediastinal masses
4 Ts:
1. thymoma
2. thyroid
3. teratoma
4. “terrible” lymphoma
can cause complete collapse
Symtoms of mediastinal mass
- changes in CO
- Syncope, sweats, orthopnea, superior vena cava obstruction
- airflow obsturction
- cough and hoarseness
- atelectasis
- CNS changes
- inability to lie flat
Surgical tx/diagnosis of mediastinal masses include:
- thoracotomy
- thoracoscopy
- mediastinoscopy
Best plan for medistinal mass OR
- Locate mass on CT before induction
- awake fiberoptic
- spontaneous respiration
be sure to have fiberoptic bronchoscope available
Complications of mediastinoscotpy
- hemorrhage
- pneumothorax
- innominate arter compression
What can occur with compression of innominate arterty
decreased cerebral blood flow
Methods of reducing risk of decreased cerebral blood flow d/t compression of innominate artery
- SPO2 and/or art line on R arm for monitoring
- NIBP on L arm to avoid interruption of monitoring on R arm
Best IV placement for anticipating hemmorage during mediastinocscopy
Large bore in lower extremity
in upper, blood given will pass through area of vascular injury and enter mediastinum
Absolute contraindciations for mediastinoscopy
previous mediastinoscopy d/t scarring
relative contraindications for mediastinoscopy
- tracheal deviation
- thoracic aortic aneurysm
- superior vena cava obsturction
Thorascopy management
art line should be placed except in extremely healthy patients
What increases bullae and why?
- PPV increases
- N2O increases
air trapping occurs
Bullae complications
- hypoxemia
- polycythemia
- cor pulmonale
- ruptured bullae can cause pneumothorax and cardiopulmonary collapse
Cullae treatment: thoracotomy to resect bullous tissue. What are anesthetic considerations?
- DLT
- No N2O
- spontaneous ventilation is preferred (reduce risk of rupture)
- Small Vt and increased rate to keep PIP below 10-20 cm H2O
- jet ventilation
Ventilator thoracotomy bullous resection strategies
want to keep PIP below ____
- Small Vt
- Increased RR
In order to keep PIP below 10 - 20