thoracic anes

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 overventilated 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.

thoracic anes

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