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7/31/2019 Thoracic Anes
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ESSENTIALS FOR MANAGEMENT OF A PATIENT UNDERGOING THORACIC SURGERY.
Preoperative considerations include pulmonary evaluation
and optimal pulmonary preparation.
Intraoperative considerations are monitoring requirements,
choice of anesthesia,
respiratory physiology of the LDP and anesthesia with one-
lung ventilation,, indications
techniques for providing anesthesia with one-lung ventilation.
postoperativeproblems of immediate life-threateningcomplications, management of mechanical ventilation,
therapeutic respiratory care maneuvers, and control of pain
are discussed
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is the tissue type amenable to surgery;
is the spread confined enough that surgery will becurable;
and third, is the patient fit for the planned operation?
The symptoms may be designated :
as bronchopulmonary,
extrapulmonary intrathoracic,
extrathoracic metastatic,
extrathoracic nonmetastatic,
and nonspecific
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THE CHEST RADIOGRAPH.
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PULMONARY FUNCTION TESTING
Resectability:
TNM staging of the disease and is based on clinical
examination, radiographic (including CT)studies (T staging),
bronchoscopic and mediastinoscopic examination (N staging),
and
evaluationand scanning of individual organs (M staging).
Operability addresses the question of how much
pulmonary tissue can be safely removed without rendering
the patient a pulmonary cripple (the remaining lung may be
diseased by a long history of smoking), and this question is
usually answered -
by pulmonary function testing.
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Preoperative pulmonary function tests and operative risk of
pneumonectomy
Phase1 PFT: Increased Operative Risk Result
Whole-lung tests
Arterial blood gases : Hypercapnia on room air
Spirometry : FEV1 < 50% of FVC
FEV1 < 2 L
MBC < 50% predicted
Lung volume :
RV/TLC > 50%
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PULMONARY
FUNCTION
TEST
(PREOP
Value vs
POSTOP
Prediction)
NORMAL PNEUMONEC
TOMY
LOBECTOMY SEGMENTA
L
RESECTION
FEV1 Liters
(measuredpreop)
>4.0 >2.11.7 >1.21.0 >0.60.9
% (measured
preop)
>80%
FVC
>50% FVC >40% FVC
>40%
>40% FVC
Liters
(predictedpostop)
- >0.90.8 >1 >0.60.9
FEV2575% Liters
(measured
preop)
>2 >1.6 0.6_1.6 >0.6
FVC Liters>5.0 >2.0
liters >5.0 >2.0 _ _
MVV Liters/min
(measured
for 1 min
preop)
100 >50 >40 >25
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% predicted
(measured
preop
100% ) >50% >40% 25%
DLCO % predicted
(measured
preop)
100 >60%
% (predicted
postop)
NA >40%
Ercercise -T
esting
Stair climbing
(measured
preop)
>10
flights
>5 flights >3 flights >2 flights
PaO2 mm Hg>90 >80 >70
>60
(whole lungmeasured
>90 >80 >70 >60
PaCO2 mm
Hg
(whole lung
measured
preop)
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SECOND PHASE
whole-lung pulmonary function values- worse proceed to the
second phase,
this phase consists of measurement of the ventilation and perfusion
of each individual lung (as a fraction of the total) by radioisotope
(133 Xe and 99 Tc)scanning.
Recently, quantitative CT has been shown to be as accurate as
perfusion scintigraphy in predicting post-operative lung function.
Combining right-left fractional lung function tests with conventionalspirometry should yield a predicted postoperative FEV1 greater
than 0.85 L.
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Single-lung tests Right-left (individual-lung) split function tests
Predicted postoperative FEV1 < 0.85L or
>70% blood flow to diseased lung
For example, if perfusion of the lung to be removed is 40% ofthe total perfusion
and the preoperative FEV1 is 1.4 L, the predicted
postoperative FEV1 will be 0.84 L.
That is, predicted postoperative FEV1 equals preoperativeFEV1 multiplied by contralateral perfusion (expressed as a
percentage).
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THIRD PHASE OF TESTING postoperative condition of the patient can be simulated by functionally
resecting the vascular bed of the lung to be excised by temporaryballoon occlusion of the major pulmonary artery on that side, with and
without exercise . Underthese conditions, the distensibility (compliance) of the remaining
pulmonary vascular bed is tested, and an increase in mean pulmonary artery pressure to greater than 40 mm
Hg,
an increase in PaCO2above 60 mm Hg, or a decrease in PaO2 to less than 45 mm Hg
or any combination of these threecriteria) indicates an inability totolerate removal of this amount of lung.
Ventilatory function after pneumonectomy (or after any resection) canalso be simulated
preoperatively by passing, with the aid of a fiberoptic bronchoscope, aballoon occlusion catheterthat can occlude either lung (or any lobe)
and then performing spirometry of the remaining lung tissue (aftercareful withdrawal of the bronchoscope)
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TESTING OF LEFT VENTRICULAR FUNCTION.
preoperative clinical predictors of perioperative cardiac
morbidity occurrence of myocardial infarction, unstable angina,
congestive heart failure, serious dysrhythmia,
cardiac death during the intraoperative or in-hospitalpostoperative periods)
recent (3 hours)operations, and thoracic or upperabdominal
The dynamic intraoperativepredictors of perioperative cardiacmorbidity are intraoperative hypotension and Tachycardia.
Hypertension remains a controversial predictor.
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PULMONARY RESECTION AND CABG:
For lesser degrees of coronary artery disease, pulmonary
resection -performed after appropriate medical therapy for
coronary insufficiency. If the patient needs CABG and limited resection can
encompass the cancer, both procedures can be performed
under the same anesthetic, but the coronary artery bypass
grafting should be done before pulmonaryresection. In cases that require large resections in compromised
patients, coronary artery bypass grafting should be done first,
and pulmonary resection should be delayed until the patient
has gained weight and muscle mass (usually 4 to 6 weeks).
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PREOPERATIVE
REPIRATORY REGIMEN
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Preoperative respiratory care regimen
1. Stop smoking, avoid industrial pollutants
2. Time Course Beneficial Effects
1224 hr Decreased CO and nicotine levels4872 hr COHb levels normalized, ciliary function improves
12 wk Decreased sputum production
46 wk PFTs improve
68 wk Immune function and metabolism normalizes812 wk Decreased overall postoperative morbidity and mortality
2. Dilate airwaysa. 2 -Agonists
b. Ipratropium bromideespecially if severe COPD
c. Inhaled steroids (systemic steroidswhen bronchospasm is
severe)
d. Cromolyn sodiummust institute before bronchospasm
L i
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5. Adjunct medication
a. Antibioticsif purulent sputum/bronchitis
b. Antacids, H2 blockers, or PPIsif symptomatic reflux.
6. Increased education, motivation, and facilitation of postoperative care
1. Incentive spirometry
2. Secretion removal maneuvers
3. Loosen secretions
a. Airway hydration (humidifier/nebulizer)
b. Systemic hydration
c. Mucolytic and expectorant drugs
4. Remove secretions
a. Postural drainage
b. Coughing
c. Chest physiotherapy (percussion and vibration)
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THE INTRAOPERATIVE PERIOD_MONITORING
Tiered
System
Patient
Category
Gas
Exchange
Airway
Mechanics
Endotrach
eal
Tube
Position
PA
Pressures
Cardiovasc
ular
Status
Tier I:
Essential
monitors
used in allPatients
Routine
healthy
patients
withoutspecial
intraopera
tive
conditions
Color of
tissues
and shed
bloodSpO2
PETCO2
Feel of the
breathing
bag,
stethoscope,
PIP,
PETCO2
EBBS
(except
ipsilateral
tubeclampbecause
ipsilateral
Breath
ounds
disappear)
.Ballotableballoon in
SSN, FOB
after
placed in
LDP
NIBP, pulse
oximeter
waveform,
ECG,PETCO2 ,
esophagea
l
stethoscop
e,
CVP, invasive
arterial
pressure
monitoring
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Tiered system Patient
category
Gas
excha
nge
Airway
mechanics
Endotrach
eal tube
position
Pa
pressures
Cardiovasc
ular status
Tier II:Special
intermittent
Or
continuous
monitoringneeds
Healthypatients
with
special
procedur
es or sickpatients
with
routine
procedur
es
ABG spirometry. FOB toverify
tube
position
while in
supineposition,
as
MeasurePpa if
lobectomy
or lung
resection
invasivearterial
pressure
monitorin
g, + CVP,
+ PAcatheter
(if poor
EF, PA,
HTN),
TEE
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a third tier of monitoring requirements is designed for patients
with significant preexisting cardiopulmonary disease who will
experience further compromising intraoperative conditions
adequacy of tissue oxygenation - SvO2 is decreased by either a
reduction in cardiac output, an increase in oxygen
consumption, or a decrease in arterial oxygen content [CaO2 ]);
Direct arterial cannulation - double-lumen endotracheal tubes
(DLTs) or serious respiratory disease , patients with serious
cardiovascular compromise.
mean pressure can be plotted over time to allow more precisemeasurement of perfusion pressure.
an increase in positive pressure-induced variation in systolic blood
pressure may be an early indicator of hypovolemia
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Normally, central venous pressure is an adequate index of
intravascular volume status.
pulmonary artery rather than a central venous catheter should
be considered if pulmonary hypertension or cor pulmonale(orboth) and coronary artery disease are present, especially if
extensive perioperative fluid shifts orblood loss is anticipated.
Special Pulmonary Vascular Monitoring Considerations
Related to Thoracotomy in the Lateral Decubitus Position:
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during right thoracotomy (left LDP), PAC -nondependent lung and therefore either
in a collapsed lung if one-lung ventilation is used or possibly
in a zone 1 or 2 region of the lung if large-tidal volume two-lung ventilation is
used. Conversely,
when a left thoracotomy is performed (patient in the right LDP), the pulmonaryartery catheter will
be in the dependent lung and will probably be in a zone 3 region. Thus, it is
theoretically possible
that the pulmonary artery catheter might function differently or yield different
pulmonary vascular pressure and cardiac output data during right versus left thoracotomy and during
two-lung versus
one-lung ventilation.
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after pneumonectomy, inflation of the balloon of the pulmonary artery catheter to obtain
Ppaw can result in considerable occlusion of the remaining cross-sectional area of the pulmonary
circulation. This occlusion acutely decreases preload on the left ventricle and increases right
ventricular afterload, thereby resulting in reduced cardiac output and reduced Pla. Although Ppaw
under these circumstances still accurately reflects Pla, both these values have been artificially lowered by the blocked pulmonary circulation; hence, they result in a falsely low Ppaw
reading.[152]
This falsely low value for left ventricular filling pressure is misleading and may result in fluid
management that contributes to the development of pulmonary edema and to the excessively high
mortality reported in postpneumonectomy patients. Advancing the catheter carefully without
inflating the balloon and wedging it into a smaller peripheral vessel can minimize the reduction in
cross-sectional area of the pulmonary vasculature. Thus, a more accurate value for Ppaw can be
obtained that reflects the true Pla.
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CLINICAL APPLICATION:
After pneumonectomy, -inflation of the balloon-Occlusion of the
remaining cross-sectional area of the pulmonary circulation acutely decreases preload on the left ventricle and increases right
ventricular afterload, thereby resulting in reduced cardiac output and
reduced Pla. -falsely low Ppaw readingdevelopment of pulmonary
edema and to the excessively high
Advancing the catheter carefully without inflating the balloon andwedging it into a smaller peripheral vessel can minimize the reduction in
cross-sectional area of the pulmonary vasculature.
Thus, a more accurate value for Ppaw can beobtained that reflects the
true Pla .
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Effect of Anesthetics on
Hypoxic Pulmonary
Vasoconstriction
HPV is an autoregulatorymechanism that protects
PaO2 by decreasing the
amount of
shunt flow that canoccur through hypoxic
lung.
When the percentage of
lung that is hypoxic is
between 30% and 70%,
which encompasses the
one-lung
ventilation/anesthesia
condition,
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Effect of Anesthetics on blood flow distribution, shunt flow, and
arterial oxygen tension (PaO2 ) during One-Lung Ventilation.
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Anesthesia Induction and Maintenance Drugs and
Techniques
INHALED ANESTHETICS:
1. salutary effect on airway irritability, bronchodilating effect related to thedepth of anesthesia
2. Obtundation of airway reflexes inpatients who have reactive airways (i.e.,
smokers)
3. allows delivery of a high inspired oxygen conncentration without loss of
anesthesia.
4. They can be rapidly eliminated, postoperative hypoventilation in
extubated patients may be diminished
5. cardiovascular stability, -history of smoking,coronary artery disease and
systemic hypertension
6. halogenated drugs do not decrease PaO2 any more than intravenous
anesthetics do during one-lung ventilation .
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NARCOTICS
1. Fentanyl no significant adverse hemodynamic effects-coronary artery
disease.
2. Second, if significant blood levels exist at the end of surgery, thenarcoticscan allow an intubated patient to have a smooth transition from
surgery to the postoperative period.
3. narcotics diminish the amount of volatile halogenated anestheti
crequired to achieve surgical levels of anesthesia.
4. In conjunction with halogenated drugs allow the use of high FIO2 withoutloss of anesthesia.
5. Narcotics donot diminish regional -optimal oxygenation during one-lung
ventilation.
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KETAMINE:
critically ill patients undergoing emergencythoracic.
Sympathomimetic- hypovolemia -thoracic procedures
sympathetically exhausted- depresses cardiovascular function.
in patients with full stomachs.,
asthmatic patients ketamine reduce bronchospasm
does not impair arterial oxygenation duringone-lung ventilation
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THORACIC EPIDURAL ANESTHESIA:
1. perform a neurologic examination on the patient before initiating
placement of the epidural catheter,2. place the thoracic epidural catheter only in an awake patient
preoperatively,
3. document theefficacy of catheter placement by obtaining a band of
anesthesia over the operative site with a testdose of local anesthetic,
4. demonstrate and document that the patient has the same neurologic5. examination (particularly in regard to motor function) that was
documented before catheterplacement, and
6. dose the catheter with an opiatecheck hemodynamic status tolerant-
add localanesthetic for the procedure
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preoxygenated by spontaneously breathing 100% oxygen
Fentanyl- of 3 to6 g/kg -respiratory rate is approximately 8 to 10
breaths/min.
sodiumthiopental (2 to 3 mg/kg), ketamine (1.0 to 2.0 mg/kgreactive
airway), or etomidate (0.1 to 0.2-hypovolemic or have impaired
cardiovascular status.
A nondepolarizing neuromuscularblockade drug
1.0% to 3.0% sevofluran.
general anesthetics significantly decrease the ventilatory response tocarbondioxide no spontaneous breathing - lead to hypercapnia
blood pressure -small doses of vasopressors, - crystalloid infusion is
minimized in patients undergoing thoracotomy unless bleeding is
encountered
The intravenous or intratracheal lidocaine (or both) will diminish both theairway and cardiovascular response to endotracheal intubation
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MAINTENANCE OF ANESTHESIA.
Relaxants are administered in small doses to keep the level of
neuromuscular blockade
IMMEDIATE EXTUBATED :sevoflurane or isoflurane (concentration ofapproximately 0.5 to1.0 MAC) and the thoracic epidural, subsequent
intravenous narcotics are avoided.
POSTOPERATIVE VENTILATION: liberal use of intravenous narcotics is
appropriate,
thoracic epidural can be reserved for later use. EXTUBATION VERSUS TUBE CHANGE.
Additional neuromuscular blockade is administered, the patient is turned
supine and placed back on 100% oxygen, the anesthetic level is ensured,
the double-lumen tube is changed to a single-lumen tube and the position
verified with endtidalCO2 monitoring, and positive-pressure ventilation isresumed.
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CLINICAL APPLICATION:
The mediastinal shift can also cause circulatory changes (decreased
venous return) and reflexes (sympathetic activation) that result in a clinical
picture similar to shock: the patient is hypotensive,pale, and cold, with
dilated pupils.
Local anesthetic infiltration of the pulmonary plexus at the hilum and
thevagus nerve can diminish these reflexes.
More practically, controlled positive-pressure ventilation abolishes these
ventilatory and circulatory changes associated with mediastinal shift.
Paradoxical breathing is increased by a large thoracotomy and by
increased airway resistance in the intact lung.
Paradoxical respiration may be prevented either by manual collapse of
the open-chest lung or, more commonly, by controlled positive-pressureventilation
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Indications for Separation of the Two Lungs
Absolute
1. Isolation of one lung from the other to avoid spillage or contamination
A. Infection
B. Massive hemorrhage
2. Control of the distribution of ventilation
A. Bronchopleural fistula
B. Bronchopleural cutaneous fistula C. Surgical opening of a major conducting airway
D. Giant unilateral lung cyst or bulla
E. Tracheobronchial tree disruption
F. Life-threatening hypoxemia from unilateral lung disease
3. Unilateral bronchopulmonary lavage
A. Pulmonary alveolar proteinosis
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Relative indications:
1. Thoracic aortic aneurysm
2. Pneumonectomy
3. Upper lobectomy
4. Esophageal resection
5. Procedures on the thoracic spine
Techniques of Lung Separation : DLTs, bronchial blockers and endobronchialtubes
DLTs favored
ability to suction secretions blindly -pediatric fiberoptic bronchoscope
during lung separation.
easier to apply CPAP to the nonventilated operative lung.
easier to rapidly convert from two-lung to one-lung ventilation.
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Disadvantages DLT:
distorted tracheobronchial tree anatomy, including exophytic andstenotic
lesions, may preclude successful correct placement or positioning of aDLT.
Second, changing from a DLT to a single-lumen tube during or at the endof long operationedematous airway- hazardous
TYPES:
Carlens
Robertshaw (PVC).
DESCRIPTION:
All double-lumen endotracheal tubes have two curves that lie in planes
approximately 90 degrees apart from one another
The distal curve is designed to facilitate placement of the distal catheter
tipinto the appropriate main stem bronchus, the proximal curve is designed to approximate the oropharyngolaryngeal
curve.
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The left-sided Carlens tube was the
first DLT used for one-lung ventilation.
The tube had a carinal hook to aid in
proper placement and minimize tubeadvancement after placement.
Problems :Laryngeal trauma during intubation,
amputation of the hook during orafter passage,
malpositioning of the tube as a result
of the hook,
and physical interference during
pneumonectomy.
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The original Robertshaw DLT, introduced in 1962, was made as a reusable
red rubber tube
The first plastic Robertshaw DLTs were made by National Catheter
Corporation, which has since become part of Mallinckrodt. Robertshaw
DLTs are now manufactured by Mallinckrodt, Rusch,Portex, and Sheridan.
The Robertshaw type of tube is presently made of a clear nontoxic
tissueimplantable plastic (denoted by the marking Z-79)
The tubes are made in sizes 41, 39, 37, 35, 28, and 26 French (the internal
diameter of each lumen is approximately 6.5, 6.0, 5.5, 5.0, 4.5, and 4.0mm, respectively).
The endobronchial cuff is
brilliant blue, which is an important recognition feature when using a
fiberoptic bronchoscope
black radiopaque line, which is an essential recognition marker when viewing a chest radiograph.
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high-volume, low-pressure tracheal and endobronchialcuffs.
The slanted doughnut-shaped endobronchial cuffallows the right upper
lobe ventilation slot to ride off (away from) the right upper lobe orifice to
minimize the chance of right upper lobe obstruction by the tube. clear tubing -tidal movement of respiratory moisture, observation of
secretions from each lung.
malleable stylets relatively easy to insert and position.
internal-to-external diameter ratios -easy to suction through, and they
also provides relatively low resistanceto ventilation.
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GUIDELINES FOR SELECTION OF DOUBLE-LUMEN ENDOTRACHEAL TUBE
TYPE (RIGHT VERSUS LEFT) AND SIZE.
Right thoracotomies : A left-sided DLT should be used for requiring
collapse of the right lung and ventilation of the left lung
Leftthoracotomies: A left-or right-sided tube may be used for requiring
collapse of the left lung and ventilation of the right lung
left-sided tube preferred : anomalous right upper lobe can takeoff from
the trachea), use of a right-sided tube for left lung collapse introduces the
risk of inadequateright upper lobe ventilation.
left-sided tube deferred : lesions that could be traumatized by the passage
of a left-sided tube. Such lesions include strictures,endoluminal tumors,
tracheobronchial disruptions, compression of the airway by an external
mass,and tenting of the left main stem bronchus so that the angle of the
takeoff from the trachea isapproximately 90 degrees.
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appropriate DLT size-correlates height
minimize airway resistance and increase the ease of passage of the
fiberoptic bronchoscope and suction catheter.
Short patients (4'6" to 5'5") should receive a 35 to 37 French left-sided
DLT;
medium-height patients (5'5" to 5'10"), a 3739 French left-sided DLT is
recommended; and for tall patients (5'11" to 6'4"), a 39 to 41 French left-sided DLT is
optimum
Young teenagers (13 to 14 years old) -use an adult-sized 35 French DLT.
The smallest left-sided DLTs made by Mallinckrodt are 32, 28, and 26
French; they can be used by 12-, 10-, and8-year-old children, respectively.
The smallest right-sided tube is the 32 French;
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distal curvature
concave anteriorly
d th f i ti d fi d h th h l d f f th
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proper depth of insertion -defined as when the cephalad surface of the
bronchial cuff is immediately below the carinal bifurcation), the average
depth of insertion for both male and female patients 170 cm tall is 29 cm,
for each 10-cm increase or decrease in height, the average placement
depth is increased or decreased by 1 cm
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morgan
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FIBEROPTIC BRONCHOSCOPY TO DETERMINE THE POSITION DLT
LDP- after skin preparation,and draping,minimal access to the chest wall
presence of unilateral or bilateral lung disease, , may markedly obscureauscultation sounds.
when the tube is just slightly malpositioned DLT location may be
confused-.
Tube movement -coughing, head flexion or extension while turning into
the LDP, or tracheal manipulation and hilarretraction by the surgeon.
subsequent fiberoptic bronchoscopy -reveal an incidence of
malpositioning as high as 78%
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ADVANTAGES OF FOB:
Thus,aside from gross malposition, important undesirable findings on
endoscopy are related to :
Excessive left cuff inflation and pressure and consist of cuff herniationover the tracheal carina,
carina ldeviation to the right (both of which may block the right main
stem bronchial orifice and impair right lung ventilation),
and excessive left lumen constriction (invagination), which may impair left
lung ventilation.
In addition, when an inappropriately undersized tube is used, the large
endobronchial cuff volume required for seal of the endobronchial cuff
tends to force the entire DLT cephalad and make a functional bronchial
seal more difficult.
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Relationship of FOB size to adult DLT tube size
Fit of Fiberoptic Bronchoscope inside DLT
(Outside Diameter) (mm) 5.6-
41 Easy passage
39 Moderately easy passage
(Outside Diameter) (mm)- 4.9-
37 Tight fit, need lubricant,
(Outside Diameter) (mm) 3.64.2All sizes Easy passage
OTHER METHODS TO DETERMINE DOUBLE LUMEN TUBE POSITION
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OTHER METHODS TO DETERMINE DOUBLE-LUMEN TUBE POSITION
1)comparison of capnography- one lung may be very poorly ventilated
inrelation to the other lung (high PETCO2 ), indicative of obstruction to
that lung
one lung may be very over- ventilated in relation to the other lung (low
PETCO2 ), perhaps indicative of ventilation of just a lobe of that lung;
capnogram from one lung may have a much steeper slope to the alveolar
plateau, indicative of expiratory obstruction
2)continuous spirometric data (DatexCapnomac Ultima) from both lungsand from each lung separately, such as pressure-volume or flow-volume
loops, may be displayed and compared with a control loop that is stored in
memory
3)the surgeon may be able to palpate the position of the DLT from within
the chest and may beable to redirect or assist in changing its position (bydeflecting the DLT away from the wrong lung,
RELATIVE CONTRAINDICATIONS TO THE USE OF DOUBLE-LUMEN ENDOTRACHEAL TUBES.
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RELATIVE CONTRAINDICATIONS TO THE USE OF DOUBLE LUMEN ENDOTRACHEAL TUBES.
1. full stomach(risk of aspiration),
2. patients who have a lesion (airway stricture, endoluminal tumor)
present along the pathway of the DLT
3. upper airway anatomy distortion (recessed jaw, prominent teeth, bull
neck, anterior larynx),
4. extremely critically ill patients whohave a single-lumen tube already in
place and who will not tolerate being taken off mechanical
5. ventilation and PEEP for even a short time,
Under these circumstances, it is still possible to separate the lungs safely
and adequately by using a single-lumen tube and fiberoptic bronchoscopic
placement of a bronchial blocker or by fiberopticbronchoscopic placementof a single-lumen tube in a main stem bronchus.
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Advantage of the Univent bronchial blocker tube
1. No need to change the tube for postoperative mechanical ventilation
2. No need to change the tube intraoperatively when turning from the
supine to the prone position3. Selective blockade of some lobes of each lung
4. Possible to apply nonventilated operative lung CPAP
Limitations to use of the Univent bronchial blocker tube
Slow deflation time :
(a) Deflate the bronchial blocker cuff and compress and evacuate the lung
through the main single lumen; (b) apply suction to the bronchial blocker
lumen
Slow reinflationtime:
(a) Deflate the bronchial blocker cuff and administer a positive-pressurebreaththrough the main single lumen; (b) carefully administer one short
high-pressure(2030 psi) jet ventilation breath
INDEPENDENT BRONCHIAL BLOCKERS.
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INDEPENDENT BRONCHIAL BLOCKERS.
The Fogarty vascular embolectomy catheter is a device designed
specifically for vascular surgery;
The common sizes of Fogarty catheter used for bronchial blockade include
6.0, 8/14,
and 8/22 catheters.
Lung separation with a single lumen tube fiberoptic bronchoscope and right lung
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Lung separation with a single-lumen tube, fiberoptic bronchoscope, and right lung
bronchial blocker.
Endobronchial Intubation with Single-Lumen Tubes
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dob o c a tubat o t S g e u e ubes
often the easiest,quickest way of effectively separating the two lungs,
especially if the left lung is bleeding
it is highly possible that the right upper lobebronchus will be blocked off- a
risk of serious hypoxemia as a result of the very large transpulmonaryshunt that is necessarily created by single-lung endobronchial intubation.s
well, with resultant ventilation of only the right middle and lowerlobes-.
If the right lung is bleeding, the single-lumen tube enters the right or left
main stem bronchus when the concavity of the tube faces anteriorly or
posteriorly, respectively.
Secondly , a fiberoptic bronchoscope -directed into the left main stem
bronchus-the single-lumen tube can then be passed over thefiberoptic
bronchoscope into the left main stem bronchus.
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PHYSIOLOGY OF ONE-LUNG VENTILATION
Effects of gravity on the
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g y
distribution of pulmonary
blood flow in the lateral
decubitus position
-The vertical gradient in the
lateral decubitus position is
less than in the upright
position.
-Consequently, there is less
zone 1 and more zone 2
and 3 blood flow in the
lateral decubitus position
than in the upright
position.
- pulmonary blood flowincreases with lung
dependency and is greater
in the dependent lung than
in the non-dependent lung
.
-Pleural pressure (Ppl)positive in
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p ( p )p
the dependent portion of the
lung, and alveoli in this region
are -most compressed and have
theleast volume )--at the apex of the lung- least
positive ,alveoli least compressed
,largest volume.
-When these regional differences
in alveolar volume are
translated to a regional
transpulmonary pressure-
alveolar volume curve
gravity also causes a vertical
gradient in pleural pressure (Ppl)
in the LDP, ventilation isrelatively increased in the
dependent as compared with the
nondependent lung
-
Distribution of ventilation in a patient in
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the lateral decubitus position
Induction of anesthesia
NDL-moves - from a flat, noncompliant
portion to a steep, compliant portion of
the pressure-volume curve
Dependent lung moves from a steep,
compliant part to a flat, noncompliant
part of the pressure-volume curve.
CAUSES:
1 -induction of general anesthesia usuallycauses a decrease in FRC.
2-the high, curved diaphragm of the
lower lung paralysed - no longer
actively contracting
3-Physical impedence by themediastinum.
4-weight of the abd contentsimpedes
expansion
5-suboptimal position of the patient. -
Increased degree of V/Q mismatching.
patient in the LDP in which the closed-chest anesthetized
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patient in the LDP in which the closed chest anesthetized
condition is compared with the open-chest anesthetized and
paralyzed condition
Opening the chest increasesnondependent lung compliance
and larger part of tidal ventilation
going to the nondependent
lung.
Paralysis also reinforces or
maintains the larger part of tidalventilation going to the
nondependent lung because the
pressure of the abdominal contents
(PAB ) pressing against the upper
part of the diaphragm is minimal
(smaller arrow),and it is therefore easier for
positive-pressure ventilation to
displace this lesser resisting dome
of the diaphragm
ventilation-perfusion relationships in an anesthetized patient in the LDP who
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has an open chest and is paralyzed and suboptimally positioned.
-The nondependent lung is
well ventilated (as indicatedby the large dashed lines) but
poorly perfused (small
perfusion vessel);
-the dependent lung is poorly
ventilated (small dashed
lines) but well perfused (large
perfusion vessel).
-In addition, an atelectatic
shunt may also develop in the
dependent lung because of
the circumferentialcompression of this lung
The increase in QS/QT in OLV is due to an obligatory right-to-left
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The increase in QS/QT in OLV is due to an obligatory right to left
transpulmonary shunt through the nonventilated nondependent lung that is not
present during twolung ventilation.
Consequently, it is not surprising to find that given the same inspired oxygen
concentration (FIO2 ) and hemodynamic and metabolic status, one-lungventilation results in a much larger PAO2 -PaO2 gradient and lower PaO2 than
two-lung ventilation does .
effect on PaCO2 than on PaO2 : Blood passing through under-
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p g gventilated alveoli retains more than a normal amount of carbondioxide and does not
take up a normal amount of oxygen;
blood traversing overventilated alveoli gives off more than anormalamount of carbon dioxide but cannot take up a proportionatelyincreased amount of oxygenbecause of the flatness of the top endof the oxyhemoglobin dissociation curve.
Thus, during onelungventilation (one-lung minute ventilation equalstwo-lung minute ventilation), the ventilated lungcan eliminate
enough carbon dioxide to compensate for the nonventilated lung,and PACO2 to PaCO2gradients are small; however, the ventilatedlung cannot take up enough oxygen to compensate forthenonventilated lung, and PAO2 to PaO2 gradients are usually large.
With constant minute ventilation(two-lung ventilation versus one-lung ventilation), retention of carbon dioxide by blood traversingthe nonventilatedlung usually slightly exceeds the increasedelimination of carbon dioxide from blood traversing theventilatedlung, and PaCO2 will usually slowly increase (along with PETCO2 ).
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DETERMINANTS OF BLOOD FLOW DISTRIBUTION DURING OLV
Surgical compression (directly compressing lung vessels) ,
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Surgical compression (directly compressing lung vessels) ,
retraction (causing kinking andtortuosity of lung vessels), ligation
of pulmonary vessels during pulmonary resection greatly
decreasesnondependent lung blood flow. If the nondependent lung is severely diseased, there may be a
fixed reduction in blood flow to this lung preoperatively-
incapable of HPV
If the nondependent lung is normal and has a normal amount of blood flow preoperatively, collapse of such a
normal lung may be associated with
higher blood flow and shunt to the nonventilated nondependent
lung. The normal response of the pulmonary vasculature to atelectasis
is anincrease in PVR (in just the atelectatic lung); due to
HPV,diverts blood flow from the atelectatic lung toward the
remaining normoxic or hyperoxic ventilated lung
1. major determinants of the amount of atelectatic lung HPV that might
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j g g
occur during anesthesia:
2. Collateral ventilation may be the first line and HPV the second line of
defense against the development of arterial hypoxemia
3. As with low V/ ratios and nitrogen-ventilated lungs, it appears that the
preponderance ofblood flow reduction in acutely atelectatic lung is due
to HPV
4. systemic vasodilator drugs either inhibit regional HPV directly or have an
effect in a clinical situation that is consistent with inhibition of regional
HPV (i.e., decreasing PaO2 andincreasing shunt in patients with acuterespiratory disease).
Vasodilator drugs-
nitroglycerinnitroprusside
dobutamine several calcium antagonists 2 -agonists(isoproterenol, ritodrine, orciprenaline, salbutamol, ATP,
Nitric oxide,
5.effect of anesthetic drugs on regional HPV
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6.The HPV response is maximal at normal and decreased at either high or low
pulmonary vascular pressure
in the OLV ,in the LDP, the fraction of cardiac output perfusing thecollapsed nondependent lung will increase with increasing pulmonary
arterial pressure (i.e., the effect ofgravity will be overcome).
when pulmonary vascular pressure decreases,part of the ventilated lung
(but not the atelectatic lung) to be in a zone 1 (alveolar pressure increases
in relation to pulmonary artery pressure) and would divert blood flowback over to the atelectatic lung, thereby inhibiting atelectatic lung HPV
7.The HPV response is also maximal when PvO2 is normal and is decreased by
either high or low PvO2 .
The mechanism for inhibition of HPV by high PvO2 is presumably due to
reverse diffusion of oxygen - the vessels will not vasoconstrict
The mechanism for inhibition of HPV by low PvO2 is a result of the low PvO2
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The mechanism for inhibition of HPV by low PvO2 is a result of the low PvO2
decreasing alveolar oxygen tension in the normoxic compartment down to a
level sufficient to induce HPV in the supposedly normoxic lung.
The HPV in the normoxic lung competes against and offsets the HPV inthe
originally hypoxic lung and results in no blood flow diversion from the more
obviously hypoxic lung.
8.Selectively decreasing FIO2 in the normoxic compartment (from 1.0 to 0.5 to
0.3) causes an increase in normoxic lung vascular tone, thereby decreasing
blood flow diversion from hypoxic to normoxic lung.
At the other extreme, prolonged exposure to hyperoxia (FIO2 of 1.0) for 68
hours blunts a subsequent whole-lung HPV response.
9.Hypocapnia has been thought to directly inhibit and hypercapnia to directly
enhance regionalHPV
Hyperventilation - increased ventilated lung airway pressure, increasedventilated lung PVR, -divert blood flow back into the hypoxic lung
Hypoventilation-hypercapnia- of the dependent lung is associated with
decreased airway pressure in the ventilated lung, PVR in the ventilated lung is
decreased,enhancing HPV in the nonventilated lung.
selective application of PEEP to only normoxic ventilated lung will selectively increase
PVR in the ventilated lung and shunt blood flow back into the hypoxic nonventilated
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PVR in the ventilated lung and shunt blood flow back into the hypoxic nonventilated
lung (i.e., decrease nonventilated lung HPV).[
BLOOD FLOW TO THE DEPENDENT VENTILATED LUNG.
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BLOOD FLOW TO THE DEPENDENT VENTILATED LUNG.
the dependent lung may also have a hypoxic compartment (area of low V/
and atelectasis) that was present preoperatively or that developed
intraoperatively.
Second, absorption atelectasis can also occur in regions of the dependent
lung that have low V/Q ratios when they are exposed to a high inspired
oxygen concentration.
Third, difficulty in removal of secretions may cause the development of
poorly ventilated and atelectatic areas in the dependent lung.
Finally, maintaining the LDP for prolonged periods may cause fluid to
transude intothe dependent lung (which may be vertically below the left
atrium) and cause a further decrease inlung volume and an increase in
airway closure in the dependent lung .
Conventional Management of One-Lung Ventilation
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Conventional Management of One Lung Ventilation
Maintain two-lung ventilation as long as possible.
Use FIO2 of 1.0:
1-A high FIO2 in the single ventilated lung may critically increase PaO2from arrhythmogenic and life-threatening levels to safer levels.
2-high FIO2 in the dependent lung causes vasodilation, thereby increasing
the dependentlung's capability of accepting blood flow redistribution as a
result of nondependent lung HPV
Begin one-lung ventilation with a tidal volume of 810 mL/kg:
Amuch smaller tidal volume might promote atelectasis of the dependent
lung; a much greater tidalvolume might excessively increase airway
pressure and vascular resistance in the dependent lung
Dependent Lung PEEP: No or just a very low level of dependent lung PEEP
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Dependent Lung PEEP: No or just a very low level of dependent lung PEEP
(
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Differential Lung Management of One-Lung
Ventilation
EFFECTS OF VARIOUS DIFFERENTIAL LUNG MANAGEMENT APPROACHES
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Selective Nondependent Lung CPAP
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Low levels of CPAP(10 cm H2 O CPAP)simply maintain the patency of
nondependent lung airways and allow some oxygen distention of thegas-
exchanging alveolar space in the nondependent lung without
significantlyaffecting the pulmonary vasculature nonventilated lung CPAP act by permitting oxygen uptake in the
nonventilated lung, as well as bycausing diversion of blood flow to the
ventilated lung, where both oxygen and carbon dioxideexchange can take
place
the nondependent lung CPAP mustbe applied during the deflation phaseof a large tidal volume so that the deflating lung can lock into aCPAP level
with uniform expansion and obviate the need to overcome the critical
opening pressureof airways and alveoli.
Differential Lung PEEP/CPAP
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ifferential ung P P/CP P
ventilated(dependent) lung is given PEEP to improve ventilated lung
volume and V/Q relationships.
Simultaneously, the nonventilated (nondependent) lungreceives CPAP inan attempt to improve oxygenation of the blood perfusing this lung.
Therefore with differential lung PEEP/CPAP-to participate in gas exchange
with alveoli that are expanded with oxygen to either ventilated or
nonventilated lung.
The use of 10 cm H2 O nondependent lung CPAP together with 10 cm H2O dependent lung PEEP caused only small, clinically in significant
hemodynamic effects in patients.
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Management of Postoperative Mechanical Ventilation
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1)first and compelling goal is to reduce FIO2 to 0.5-PaO2 > 60mm Hg-PEEP
titration
(2) PEEP < 10 cm H2 O ,FIO2 < 0.5 PaO2 > 60mm Hg
(3) reduce the IMV rate to less than 1 breath/minFIO2 < 0.5 PEEP to 60mm Hg,vital capacity is larger than 15 mL/kg, peak
inspiratory forceis greater than -25 cm H2 O, the spontaneous
respiratoryrate is less than 20 to 30/min, and PaO2 is approximately 40
mm Hg .
when no other major organ systems are in acute major failure or are
unstable;
and when the chest roentgenogram findings are reasonably equivalent to
the premorbid findings or are rapidly improving and no new changeshave
appeared (such as infiltrates or pneumothorax).
Management of Postoperative Pain
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Splinting, active exhalation, and failure to coughpromote retention of
secretions, airway closure, and atelectasis
Cryoanalgesia
intercostal nerve block may be achieved by intercostal nerve
freezing(cryoanalgesia) .
Return of sensation occurs in most patients by the 30th postoperative day
incidence of dysesthesia and intercostal muscle paralysis,
Epidural Analgesia Thoracic epidural analgesia is the current gold standard for post-
thoracotomy
Analgesia combined opiate and dilute local anesthetic diminishes the
major toxicity of eachdrug type and maximizes the therapeutic
benefit.[448]
We administer a combination of low-dosehydromorphone (Dilaudid) and
dilute bupivacaine and achieve excellent postoperative analgesia
Interpleural Regional Analgesia
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catheter tip islocated and a local anesthetic is deposited between the two
layers of the pleura,
good pain relief, increased pulmonary function, decreased narcotic
requirements
A review covering a total of 703 cases has detailed the complications of
interpleural analgesics
Pneumothorax was the most frequently registered complication (2.0%),
followed by signs of
systemic toxicity (1.2% [in one patient seizures were thought to be due to
rapid uptake because of
the presence of a highly inflamed pleura and pleural effusion (0.42%).
Horner's syndrome,
pleural infections, and catheter rupture have also been reported.