Anesthesia for Thoracic Surgery Flashcards
Positioning for Thoracic Surgery
lateral decubitus
complications with positioning
coughing, tachycardia, hypertension during turn to lateral
HoTN from blood pooling in dependent portions
VQ mismatching and hypoxemia
interstitial pulmonary edema of dependent lung
brachial plexus and peroneal nerve injury
monocular blindness (dependent eye ischemia)
outer ear ischemia (flat or in donut)
axillary artery compression
ventilatory mechanics of awake and upright spontaneously breathing patient with a closed chest (ventilation and perfusion)
apex of lungs are minimally dilated
most Ventilation occurs at the base of the lungs
perfusion also favors the base of the lungs
VQ mismatching is preserved during spontaneous respirations
zone 1 of an upright lung, relationship between alveoli, pulmonary artery, pulmonary vein
pA>pa>pv
zone 2 of an upright lung, relationship between alveoli, pulmonary artery, pulmonary vein
pa>pA>pv
zone 3 of an upright lung, relationship between alveoli, pulmonary artery, pulmonary vein
pa>pv>pA
where is V/Q most efficient in an upright lung
zones 2 and 3
ventilatory mechanics of an awake patient in lateral decubitus position with a closed chest and spontaneous respirations
VQ matching is preserved
dependent lung receives more ventilation and perfusion than upper lung (non dependent lung)
where do the zones of the lungs lie for a lateral decubitus patient who is awake and spontaneously breathing
zone 1 is the top of the nondependent lung, zone 2 is the bottom 2/3 of the nondependent lung and the top 1/3 of the dependent lung, and zone 3 is the bottom 2/3 of the dependent lung
factors that incite progressive cephalad displacement of the diaphragm
surgical positioning and displacement, paralysis, induction of anesthesia, supine positioning
ventilatory mechanics and factors affecting an anesthetized patient in lateral decubitus position, paralyzed, with a closed chest and 2 lung ventilation
PPV, decrease in FRC, VQ mismatching, dependent lung has greater perfusion while nondependent lung has greater ventilation and Vt
ventilatory mechanics and factors affecting an anesthetized patient in lateral decubitus position with an open chest and 2 lung ventilation
PPV helps overcome pneumothorax, VQ mismatching occurring, perfusion remains greater in dependent lung, upper lung collapse leads to progressive hypoxemia via mediastinal shift and resultant paradoxical respirations.
pneumothorax creates loss of negative pressure to open lung
inspiration during a pneumothorax
increases pneumothorax size and increases VQ mismatching
VQ mismatch in the non dependent versus dependent regions summary
non dependent V>Q, dependent Q>V
what is the big effect of an open chest
mediastinal shift
HPV
diverts blood away from hypoxic regions of the lung
decreased BF to the non ventilated lung
helps improve arterial oxygen content, improving hypoxemia
decreases shunt
average of both lungs being nondependent: blood flow distribution during two lung ventilation in the lateral position
top lung averages at 40% blood flow while bottom lung averages at 60% blood flow
HPV response during one lung ventilation in the lateral decubitus position (no inhalational influence)
there is a 50% HPV response in the dependent lung, so BF therefore increases to 80% in the dependent lung and decreases to 20% in the non dependent non ventilated lung
Factors that inhibit HPV (6)
high PVR, hypocapnia, high or very low mixed venous pO2, vasodilators, pulmonary infection, inhalation anesthetics
what is capable of increasing PVR (3)
high PAP, volume overload, mitral stenosis
vasodilators that inhibit HPV examples (4)
nitroglycerin
sodium nitroprusside
beta agonists (dobutamine)
CCB’s
1 MAC of inhalational = ___ increase in VQ shunt via inhibition of HPV by ____
4%
21%
which inhalational gases are not as inhibitory of HPV
desflurane and sevoflurane are not as inhibitory as isoflurane
1 MAC of isoflurane inhibits HPV by ____% and therefore increases the VQ shunt
21%
benefits of one lung anesthesia (4)
better operating conditions with collapse of diseased lung
facilitates access to aorta and esophagus
prevents cross contamination with abscess, secretions, blood
prevents loss of anesthetic gases with bronchopleural fistula
relative contraindications for one lung anesthesia (2)
difficult airway with poor visualization of the larynx
lesion in bronchial airway precluding bronchial intubation
absolute indications for one lung ventilation (OLV)
pulmonary infection copious bleeding on one side bronchopulmonary fistula bronchial rupture large lung cyst bronchopleural lavage
relative indications for one lung ventilation (6)
thoracic aortic aneurysm pneumonectomy lobectomy thoracotomy, thoracoscopy subsegmental resections esophageal surgery
techniques for achieving one lung ventilation (OLV)
double lumen ETT bronchial blocker (used with standard single lumen ETT) single lumen ETT with bronchial blocker built in
double lumen endotracheal tube (DLT) shared characteristics
longer bronchial lumen which enters the right or left mainstream bronchus
shorter tracheal lumen remaining in distal trachea
preformed curve that allows preferential entry into the left or right side
separate bronchial and tracheal cuffs (with separate balloons)
tubes specifically designed for left or right side due to differences in anatomy
double lumen tube cuff sizes and stylet considerations
bronchial cuff is 3cc and the tracheal cuff is 6cc. the stylet goes through the bronchial side. the concave portion and the tip face up during initial insertion
anatomic considerations of the adult trachea: length, where it begins, where it bifurcates
11-12cm in length, begins at C6 (cricoid cartilage), bifurcates at the sternomanubrial joint (T5)
anatomic considerations of right bronchus: width, angle, orifice of RUL in relation to carina
wider, diverges away from trachea at 20-25 degree angle, orifice of RUL sits only 1-2cm to carina
anatomic considerations of left bronchus: width, angle, orifice of LUL in relation to carina
narrower, diverges away from trachea at 40-45 degree angle, orifice of LUL sits about 5cm distal to carina
big difference in right versus left double lumen tube?
right sided tube has murphys eye for the RUL
what is the best predictor of DLT size?
height
what size DLT for women and what size DLT for men usually?
35-37 women
37-39 men
(tall, 41fr available)
insertion technique for DLT
laryngoscopy with curved blade provides optimal space to place DLT (mac>miller)
DLT is passed with distal curvature concave anteriorly, then rotated 90 degrees towards the right side that is to be intubated after the tip enters the larynx (or rotate once bronchial cuff is at cords)
advance DLT until resistance is felt
confirm correct placement via bronchoscopy
average insertion depth of DLT
28-29 cm at teeth
how to listen for correct positioning
clamp left bronchial side, hear breath sounds on both. clamp tracheal lumen, BS on left
protocol for checking placement?
inflate tracheal cuff (5-10mL of air) and check for bilateral breath sounds
inflate bronchial cuff (1-2mL of air) and clamp tracheal lumen. check for unilateral LEFT breath sounds
unclamp tracheal lumen and clamp bronchial lumen. check for unilateral right breath sounds
fiberoptic confirmation (both supine and after LDP)
if you inflate the tracheal cuff to check for bilateral breath sounds and only hear unilateral breath sounds, what can you assume
tube is too far down and tracheal opening is endobronchial
if you check for unilateral left breath sounds and hear persistent right sided breath sounds on a DLT, what can you assume?
bronchial opening still in trachea and tube should be advanced.
common problems with DLT placement include (3)
in too far, not far enough, wrong side
most common problem encountered with positioning a left endobronchial tube?
inserting too deeply, excluding right lung from ventilation
most common problem encountered when positioning a right endobronchial tube?
excluding the RUL from ventilation
what are left endobronchial tubes used for?
right sided thoracotomy. tracheal lumen is clamped and left lung is ventilated though bronchial lumen.
used also for left sided thoracotomy. bronchial lumen is clamped and right lung is ventilated through tracheal lumen
if surgeon needs to clamp the left mainstem of a left endobronchial tube for a pneumonectomy
move bronchial lumen into the trachea and then use a standard ETT
indications for a right DLT include
resection of a thoracic aortic aneurysm
tumor in left mainstem bronchus
left lung transplantation or left pneumonectomy (not absolute)
left sided tracheo bronchial disruption
explain bronchial blockers
inflatable devices passed alongside or though a single lumen ETT to selectively occlude a bronchial orifice
what is a univent tube
single lumen ETT with built in side channel for retractable bronchial blocker
how to use regular ett with bronchial blocker
regular ett is used with inflatable catheter (fogarty catheter), guide wire used for placement
explain how to insert a bronchial blocker
must be advanced, positioned, and inflated under direct visualization via a flexible bronchoscope. adapter still allows you to ventilate during placement
“major advantage” to bronchial blockers
patient who requires intubation postoperatively-do not have to redo their laryngoscopy and change out ETT
“major disadvantage” to bronchial blockers
blocked lung collapses slowly (due to lumen size) and sometimes incompletely
how to insert univent bronchial blocker
ETT is placed with blocker fully retracted
ETT is then turned 90 degrees towards the operative side
bronchial blocker is pushed to the mainstream bronchus under direct visualization with fiberoptic scope
describe ventilation during insertion of univent bronchial blocker with a fiberoptic scope
fiberoptic scope passed through adapter with self sealing diaphragm allowing uninterrupted ventilation
what can the channel on the univent bronchial blocker be used for
suctioning, deflating, insufflating
describe the utilization of a fogarty catheter
used with standard ETT, guide wire in catheter is used to facilitate placement through ETT
does not allow suctioning or ventilation of isolated lung.
(same as clot plasty balloon thing)
indications for a lung resection
diagnosis and tx of pulmonary tumors
necrotizing pulmonary infections
bronchiectasis
preoperative testing for lung resection
CXR/CT EKG/cardiac studies ABG PFT's VQ tests, especially important in lung that will be left to pick up the slack
risk assessment based on FEV1
FEV1>2L or 80% predicts low risk
FEV1<2L or 40% predicts high risk
risk assessment for pneumonectomy: ABG
PaCO2 >45mmHg on RA or PaO2 <50mmHg
risk assessment for pneumonectomy: FEV1/FVC
<50% of predicted
risk assessment for pneumonectomy: VO2
<10mL/kg/min
risk assessment for pnuemonectomy: maximum voluntary ventilation
<50% of predicted
preoperative evaluation for pneumonectomy: describe split lung function tests
- uses ratio labeled albumin to calculate the predicted pulmonary function, postoperative outcome, and survival after pneumonectomy.
- predicts FEV1 of an isolated lung if the other lung is removed
- minimal predicted postoperative FEV1 necessary for long term survival 800-1000mL
formula for predicted postoperative FEV1?
preoperative total FEV1X % BF to remaining lung
which chemotherapeutic agents can be responsible for cardiomyopathy and would prompt the need for a preoperative echocardiogram? (2)
doxorubicin (Adriamycin)
Cyclophosphamide (Cytoxan)
which chemotherapeutic agents can be responsible for pulmonary toxicity? (3)
bleomycin (pulmonary toxicity with high FiO2)
mitomycin c
cyclophosphamide
which chemotherapeutic agents can be responsible for bone marrow suppression and therefore warrant a preoperative CBC
most chemotherapeutic agents-check platelets, RBC’s, WBC’s
what paraneoplastic syndromes can small cell lung carcinoma be responsible for? (3)
SIADH
LEMS
Carcinoid Syndrome
Oat Cell Carcinoma (Small Cell Lung Carcinoma) may cause
low UOP hypervolemia hyponatremia CHF Pedema
what paraneoplastic syndrome is non small cell lung carcinoma responsible for?
ectopic parathyroid hormone
Assessment of patients with lung cancer: 4 M’s
mass effects
metabolic effects
metastasis (brain, liver, bone, adrenals)
medications (chemo induced lung/cardiac changes)
describe “mass effects” assessment of patients with lung cancer (5)
obstructive PNA, SVC syndrome, tracheobronchial distortion, RLN or phrenic nerve paresis
describe “metabolic effects” assessment of patients with lung cancer
LEMS, hypercalcemia, hyponatremia, cushings syndrome
patient preparation: premedication to consider
bronchodilators
anticholinergics (secretions, also increases HR to counteract vagus nerve stimulation when pleura is opened)
monitoring equipment to consider during a one lung ventilation case
arterial line (everyone gets one. place on dependent limb) CVP: not necessary, but desirable to guide fluid managment PA cath: LV dysfunction or severe pHTN
airway equipment to consider having available during one lung ventilation case
multiple sized DLT’s, standard ETT available
pedes FOB, difficult AW card
what can you consider for postoperative pain mangement
thoracic epidural
positioning considerations for one lung ventilation
properly placed axillary roll to protect brachial plexus. check tube with bronchoscope after positioning
fluid management considerations during one lung ventilation
2 large bore PIV’s, avoid over hydration
have blood warmer and rapid infusion device available
T&C and PRBC’s
one lung ventilation management after induction and before pleura is opened
get baseline ABG prior to OLV
maintain 2 lung ventilation until pleura is opened
one lung ventilation surgery management: during first incision to get to pleura opening
need maximum depth of anesthesia with chest opening and rib splitting
initiation of one lung ventilation during surgery: management and considerations
100% O2 to dependent lung
obtain ABG 15 minutes after OLV is initiated, guide therapy to maintain near baseline
major adjustments in ventilation usually not necessary
greatest risk of one lung ventilation
hypoxemia
what do you do if you have high peak pressures during one lung ventilation
check ETT position, reduce VT and increase RRR to maintain minute ventilation
ventilation of dependent lung: FiO2/Vt/RR/PEEP
FiO2: 100%, can decrease after ABG obtained
Vt 5-6mL/kg, not necessary to change with OLV
RR 12-15 to keep PaCO2 35-45mmHg (or close to preop value)
PEEP 0-5mmHg
PEEP and patients with COPD during OLV
dont add PEEP
how much does EtCO2 increase during OLV
1-3mmHg
which mode is suggested for OLV
pressure control
if the patient experiences hypoxemia during OLV, these are the suggested steps
confirm tube placement and increase FiO2 to 100%
check hemodynamic status
adjust Vt/RR
add 2-10cmH2O CPAP to collapsed lung
periodically inflate collapsed lung with 100% O2
add 5-10cmH2O PEEP to dependent lung
continuous insufflation to collapsed lung with 100% O2
early ligation/clamping of ipsilateral pulmonary artery (if doing pneumonectomy). BF goes to other lung
complications from thoracic anesthesia: hypoxemia and respiratory acidosis causes
atelectasis and shallow breathing (splinting) due to incisional pain
gravity dependent transudation of fluid into dependent lung
complications from thoracic anesthesia: postoperative hemorrhage signs
(associated with 20% mortality)
signs: chest tube drainage >200mL/min, hypotension, tachycardia, decreasing HCT
complications from thoracic anesthesia: 4 others (not including hypoxemia and postoperative hemorrhage)
arrhtyhmias
bronchial rupture (due to excessive cuff inflation of bronchial tube)
acute RV failure (low CO, elevated CVP, oliguria)
positioning injuries
