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Principle of thoracic anesthesia with determinants of operability for resection, One lung anesthesia
Dr. Rajesh Kumar
University College of Medical Sciences & GTB Hospital, Delhi
Indication/contraindication of OLV Physiological changes of OLV Lung separation techniques and
equipments
•Objectives
One-lung ventilation, OLV, means separation of the two lungs and each lung functioning independently.
OLV provides:◦ Protection of healthy lung from infected/bleeding
one◦ Diversion of ventilation from damaged airway or
lung◦ Improved exposure of surgical field
OLV causes:◦ More manipulation of airway, more damage ◦ Significant physiologic change and easily
development of hypoxemia
•Introduction
Absolute ◦ Isolation of one lung from the other to avoid spillage
or contamination Infection Massive hemorrhage
◦ Control of the distribution of ventilation Bronchopleural fistula Bronchopleural cutaneous fistula Surgical opening of a major conducting airway giant unilateral lung cyst or bulla Tracheobronchial tree disruption Life-threatening hypoxemia due to unilateral lung
disease◦ Unilateral bronchopulmonary lavage
•Indication
Relative◦ Surgical exposure ( high priority)
Thoracic aortic aneurysm Pneumonectomy Upper lobectomy Mediastinal exposure Thoracoscopy
◦ Surgical exposure (low priority) Middle and lower lobectomies and subsegmental resections Esophageal surgery Thoracic spine procedure Minimal invasive cardiac surgery (MID-CABG, TMR)
◦ Postcardiopulmonary bypass status after removal of totally occluding chronic unilateral pulmonary emboli
◦ Severe hypoxemia due to unilateral lung disease
•Indication (continued)
Upright position LDP, lateral decubitus position
•Physiology of the LDP
Distribution of ventilation
•Physiology of LDP
Physiological (postpulmonary) shunt About 2-5% CO, Accounting for normal A-aD02, 10-15 mmHg Including drainages from
Thebesian veins of the heart The pulmonary bronchial veins Mediastinal and pleural veins
Transpulmonary shunt increased due to continued perfusion of the atelectatic lung and A-aD02 may increase
•Shunt and OLV
•Two-lung Ventilation and OLV
•OLV and shunt fraction with and without anesthesia
Protective influences in response to the obligatory pulmonary shunt includes the hypoxic pulmonary vasoconstriction, HPV .
HPV, a local response of pulmonary artery smooth muscle, decreases blood flow to the area of lung where a low alveolar oxygen pressure is sensed.
•Physiology of OLV
The mechanism of HPV is not completely understood. Vasoactive substances released by hypoxia or hypoxia itself (K+ channel) cause pulmonary artery smooth muscle contraction
HPV is graded and limited, of greatest benefit when 30% to 70% of the lung is made hypoxic.
But effective only when there are normoxic areas of the lung available to receive the diverted blood flow
•HPV
HPV is inhibited by: volatile anesthetics (not N20),
vasodilators (NTG, SNP, dobutamine, many ß2-agonist),
increased PVR and hypocapnia
PEEP, vasoconstrictor drugs
(preferentially constrict normoxic lung vessels)
•Factors Affecting Regional HPV
Double-lumen endotracheal tube (DLT) Single-lumen ET with a built-in bronchial
blocker, Univent Tube Single-lumen ET with an isolated bronchial
blocker◦ Arndt (wire-guided) endobronchial blocker set◦ Balloon-tipped luminal catheters
Endobronchial intubation with a single-lumen ET
•Methods of OLV
Type:◦ Carlens, a left-sided + a carinal hook ◦ White, a right-sided Carlens tube◦ Bryce-Smith, no hook but a slotted cuff/Rt ◦ Robertshaw, most widely used
All have two lumina/cuffs, one terminating in the trachea and the other in the mainstem bronchus
Right-sided or left-sided available Available size: 41,39, 37, 35,32, 28,26
French (ID=,10.0,9.5,9.0, 8.5, 8.0, 7.0 and 6.5 mm respectively)
•DLT
Schematic diagram depicting passage of the left-sided double-lumen endotracheal tube in a supine patient.A, The tube is held with the distal curvature concave anteriorly and the proximal curve concave to the right and in aplane parallel to the floor. The tube is then inserted through the vocal cords until the bronchial cuff passes the vocalcords. The stylet is then removed. B, The tube is rotated 90 degrees counterclockwise so that the distal curvature isconcave anteriorly and the proximal curvature is concave to the left and in a plane parallel to the floor. C, The tube isinserted until either mild resistance to further passage is encountered or the end of the common molding of the twolumens is at the teeth. Both cuffs are then inflated, and both lungs are ventilated. Finally, one side is clamped while theother side is ventilated and vice versa
1. Blind technique Caution: DLT should pass without any resistanceOptimal depth of insertion for a left sided DLT is ~ patients height ~ 12 +(patients height/10) cm
2. Direct vision technique: uses fiberoptic bronchoscope, however both methods results in successful
placement in approx equal number of patients
•Method of insertion
Alternately blocking the tracheal and bronchial lumen and checking for the air entry.
With the help of fiberoptic bronchoscopy
Chest –x ray
•Confirming position of DLT
•Confirming Position of DLT………
Sex Height(cm) Size(Fr)
Female <160 (63 inches)
35
Female >160 37
Male <170 (67 inches)
39
Male >170 41
•Selection of DLT based on adult patient sex and height
Margin of safety is low : 1. Rt. Upper lobe bronchus is short 2. Rt. u/l bronchus originates at a
distance of 1.5-2 cm from the carina
Fewer indications Doughnut shaped cuff Additional opening for the ventilation of
right upper lobe.
•Right sided DLT
Distorted anatomy of the entrance of a left main stem bronchus
•External or intraluminal tumaour compression•Descending thoracic artery aneurysm
Site of surgery involving the left main stem bronchus
•Left lung transplantation•Left sided tracheobronchial disruption•Left sided pneumonectomy•Left sided sleeve resection
•Indications for a right sided DLT
Most commonly used The bronchial lumen is longer, and a simple
round opening and symmetric cuff. Better margin of safety than Rt DLT
Can be used
◦ Left lung isolation: clamp bronchial + ventilate/ tracheal lumen◦ Right lung isolation: clamp tracheal + ventilate/bronchial lumen
•Left DLT
5%-8% of patients with primary lung carcinoma have a carcinoma of the pharynx as well
Many of these patients have previous radiation exposure or previous surgery done.
They might have distorted anatomy at or beyond carina. eg…descending thoracic aortic aneurysm, intraluminal or extraluminal tumour
Can be detected by chest-x ray and CT scan
•Difficult airway and OLV
A flexible fiberoptic bronchoscopy is essential
Primary goal is to establish an airway with the help of a SLT (awake or anesthetised) f/b the insertion of bronchial blockers.
An alternative is to insert a SLT and then insert DLT with the help of a tube exchanger
•Approach to difficult airway
1. Insertion of a SLT f/b an independent bronchial blocker
2. Use of a disposable cuffed tracheostomy cannula with an independent bb passed coaxially
3. Replacement of the tracheostomy canula with a short DLT such as NARUKE DLT
4. Placement of a small DLT through tracheostomy stoma
5. Oral access to the airway for standard placement of a DLT or blocker
•In a tracheostomised patient
Preanesthetic assessment
Anesthetic management
Postoperative management
•objectives
Fundamentals to anesthetic management of thoracic procedures
•Lung isolation to facilitate surgical access•Management of one lung anesthesia
Preoperative evaluation
done in two disjoint phases:
1. The initial clinical assessment2. The final assessment on the day
of admission
Primary function of PAC
•To identify patients at elevated risk, •To stratify perioperative management and focus resources
•Feasibility of lung resection in a high risk patient
complication incidence
Respiratory(atelectasis, pneumonia,respiratory failure)
15-20 %
Cardiovascular(arrhythmia and ischemia)
10-15%
•Perioperative complications(overall mortality 3-4%)
History Detailed history regarding the quality of life preoperatively
Respiratory mechanics
All patients should have a baseline spirometry:
•FEV1, FVC, MVV, RV/TLC
•FEV1% ( % of predicted volume corrected for age,gender and height).
•ppo FEV1 % ( predicted post operative FEV1 ) Calculated as ppoFEV1 % = preop FEV1 % (1-% functional lung tissue removed/100)
ppo FEV1 % > 40% low riskppoFEV1 % <40% major complicationppo FEV1 % <30% high risk
• Assessment of respiratory functions
Lung parenchymal tests
•ABG parameter : PaO2 < 60mm Hg PaCO2 >45 mmHg( warning indicator of increased risk, however resections are done with these figures nowadays)
•Most useful test : DLCO ppo DLco can be calculated like ppo FEV1•ppo DLco < 40 % increases respiratory and cardiac complications
•PREOP. FEV1 OR DLco < 20% Is UNACCEPTABLE and is the absolute MINIMAL value required. ( national emphysema treatment trial )
•Assessment of respiratory functions continued……………
Laboratory exercise testing
•Gold standard•Vo2 max (maximum oxygen consumption) is the most useful predictor of post operative outcome.•Vo2 max < 15 ml/kg/min is unacceptable•Vo2 max >20 ml/kg/min has fewer complication
EXPENSIVE
Stair climbing tests
•5 flights of stairs ~ V02 max >20 ml/kg/min•2 fight of stairs ~ Vo2 max ~ 12 ml/kg/min -- very high risk(climbing should be at patients own pace without stopping,1 flight of stairs = 20 steps withs each step of 6 inches )
• Assessment of respiratory functions continues………
cardiopulmonary interactions(most important assessment of respiratory function)
Six minute walk test(6MWT)
< 610 m/ 2000 ft ------ Vo2 max< 15 ml/kg/min ~fall in SpO2 > 4% during exercise( increased morbidity and mortality)
ppo V02 max < 10 ml/kg/min is an absolute contraindication mortality rate is approximately 100%
V-P scintigraphy
Should be considerd for any patient of pneumonenctomy having a preop FEV1 &/or Dlco <80%• performed at rest while FEV1 is a forced maneuver
• Assessment of repiratory functions continues……………
Split lung function test
•These tests have not shown sufficient predictive value or validity for universal adoption and are hence not recommended any longer
•Replaced by spirometry/ DLco/ exercise tolerance & V/Q scaning.
• Assessment of repiratory functions continued……………
Respiratory mechanics
FEV1(ppo>40%) MVV, RV/TLC, FVC
Cardiopulmonary reserve
Vo2 max >15ml/kg/min
Stair climbing>2 flight
6MWT>610m/2000ft
Exercise SpO2 < 4 %
Lung parenchymal
function
Dlco (ppo >40%) PaO2 >60PaCO2 <45
• The three legged stool of pre thoracotomy respiratory assessment
•Ischemia : intermediate risk surgery
• 5% incidence post thoracotomy
• peaks on 2 and 3rd post op day
• ACC/AHA guidelines to be followed
•Arrhythmias•Right ventricular
dysfunction
cardiovascular
•Perioperative mortality is 19% in pt. developing deranged KFT in periop. Period as against 0% in those having normal KFT
•Increased risk in pt. having h/o renal impairment
• use of diuretic
• use of NSAIDS
•Hence I/op fluid management and intensive perioperative fluid management is essential
Renal dysfunction
•Rate of respiratory complication doubles(40%) and cardiac complications (40%) triples in elderly
Age
•Concomitant medical conditions
Problems in a COPD patient
Respiratory drive,CO2 retainers,
Increased role of HPV
Nocturnal hpoxemia because of rapid shallow breathing in a REM sleep
Right ventricular dysfunctionBullaeFlow limitation : stage I :FEV!>50% no significant dyspnoea ,hypoxemia or hypercapniaStage III :FEV1 <35% --life expectancy <3 years post thoracotomy
•Concomitant medical conditions continues…….
Time Course Beneficial Effects
12–24 hr Decreased CO and nicotine levels
48–72 hr COHb levels normalized, ciliary function improves
1–2 wk Decreased sputum production
4–6 wk PFTs improve
6–8 wk Immune function and metabolism normalizes
8–12 wk Decreased overall postoperative morbidity and mortality
•Beneficial effects of smoking cessation and time course
Mass effects Obstructive pneumonia,lung abscess, superior vena cava syndrome, tracheobronchial distortion , pancoast syndrome, recurrent laryngeal nerve or phrenic nerve palsy, chest wall or mediastinal extension
Metabolic effect
Lambert – Eaton syndrome, hypercalcemia, hyponatremia, cushing syndrome
Metastases Particularly to brain, bone , liver and adrenal
Medications Chemotherapy agents , pulmonary toxicity ( bleomycin,mitomycin C), cardiac toxicity(doxorubicin), renal toxicity ( cisplatin )
•Anesthetic considerations in lung cancer patients (“the 4 Ms” )
•Preoperative therapy for COPD
the risks and benefits of the
various forms of post-
thoracotomy analgesia should be explained to
the patient
Potential contraindication
s such as coagulation problems, sepsis, or neurologic
disorders should be determined
American Society of Regional
Anesthesia (ASRA)
an interval of 2 to 4 hours
before or 1 hour after catheter placement for prophylactic
heparin administration.
an interval of 12 to 24 hours
before and 24 hours after
catheter placement is
recommended for LMWH
•To discuss post op analgesia
>40%
•Extubate in the OR
•Patient AWaC (alert ,warm and comfortable)
30-
40%
•Extubation on the basis of
•Exercise tolerance,Dlco,V/Q scan, associated diseases
<30%
•Staged weaning
•Consider extubation if >20% + thoracic epidural analgesia
• Think about post thoracotomy anesthetic management(based on ppo FEV1%)
High percentage of ventilation or perfusion to the operative lung
preoperatively
Poor PaO2 during two-lung ventilation particularly in the lateral position
intraoperatively
Right sided thoracotomy
Normal preoperative spirometry or restrictive lung disease
Supine position during OLV
• Increased risk of hypoxemia
avoid inadvertent withdrawal of those drugs that are taken for concurrent medical conditions
For surgeries like oesophageal reflux surgeries aspiration prophylaxis are routinely ordered preoperatively
do not routinely order preoperative sedation or analgesia for pulmonary resection patients
Mild sedation short-acting benzodiazepine is often given immediately before placement of invasive monitoring lines and catheters.
an antisialagogue (e.g., glycopyrrolate) is useful to facilitate fiberoptic bronchoscopy
It is a common practice to use short-term intravenous antibacterial prophylaxis
•Premedication
Oxygenation : significant desaturation( SpO2<90%) occurs in 1-10% of
patients inspite of high FiO2 (1.0). PaO2 offers a better margin of safety then SpO2 Decreased initial PaO2 and rapid fall in PaO2 after initiation
of OLV is a good indicator of subsequent desaturation. Useful to measure PaO2 before and 20 minutes after OLV
Capnometry Less reliable then PaCO2 PaCO2-EtCO2 gradient increased
Other components of minimum mandatory monitoring : BP,ECG,temperature
•Intraoperative monitoring
Arterial line:Surgical compression of heart & great vessels l/t hypotension•CVP : non reliable , useful postoperatively•Pulmonary artery catheters: less reliable for OLV• unsurety about the location of the tip• signficant u/l differences in lung perfusion.• complications
Continuous spirometry monitoring of inspired and expired volume auto-PEEP•aids in assessing and managing pulmonary air leak during
pulmonary resection
Transesophageal echocardiography :continuous real time monitoring ofmyocardial function and preload•Potential indication: hemodynamic instability,pericardial
effusion,cardiac involvement by tumour,air emboli,pulmonary thromboendarterectomy, thoracic trauma,lung transplantation.
•Difficult in pt. having esophageal pathology,
•Invasive monitoring
The majority of thoracic procedures are performed with the patient in the lateral position
monitors will be placed and anesthesia will usually be induced with the patient in the supine position
hypotension on turning the patient to or from the lateral position
All lines and monitors will have to be secured during position change and their function reassessed after repositioning
anesthesiologist should take responsibility for the head, neck, and airway during position change
Endobronchial tube/blocker position and the adequacy of ventilation must be rechecked by auscultation and fiberoptic bronchoscopy after patient repositioning.
•Positioning
1. Dependent eye 2. Dependent ear pinna 3. Cervical spine in line with thoracic spine 4. Dependent arm: a. Brachial plexus b. Circulation 5. Nondependent arm : a. Brachial plexus b. Circulation
• “Head-to-toe” survey for neurovascular injury after position change
Fluid Management for Pulmonary Resection Surgery
1. Total positive fluid balance in the first 24-hour perioperative period should not exceed 20 mL/kg.
2. For an average adult patient, crystalloid administration should be limited to < 3 L in the first 24 hours.
3. There should be no fluid administration for third space fluid losses during pulmonary resection.
4. Urine output > 0.5 mL/kg/hr is unnecessary.
5. If increased tissue perfusion is needed postoperatively, it is preferable to use invasive monitoring and inotropes rather than to cause fluid overload.
•Anesthetic management
use of N2O/O2 mixtures is associated with a higher incidence of post-thoracotomy radiographic atelectasis (51%) in the dependent lung than when
air/oxygen mixtures are used (24%).
also tends to increase pulmonary artery pressures in patients who have pulmonary hypertension
N2O inhibits HPV
N2O is contraindicated in patients with blebs or bullae
N2O is usually avoided during thoracic anesthesia
Use of nitrous oxide
anesthetic technique should optimize the myocardial oxygen supply/demand
Thoracic epidural anesthesia/analgesia is recommended high incidence of coexisting reactive airway disease,
added airway manipulation by the DLT or bronchial blocker
Thus, need anesthetic technique that decreases bronchial irritability, causes bronchodilation, and avoids release of histamine
For intravenous induction of anesthesia either propofol or ketamine, & for maintenance of anesthesia, propofol and/or any of the volatile anesthetics are recommended
•Cardiovascular and Respiratory goals
All of the volatile anesthetics inhibit HPV in a dose-dependent fashion :
◦ halothane > enflurane > isoflurane
In doses less than or equal to 1 MAC, the modern volatile anesthetics depress HPV minimally
Hence TIVA has no proven benefit against 1 MAC inhalational anesthesia
•Choice of Anesthetic
Parameter Suggested Guidelines/ Exceptions
Tidal volume 5-6 mL/kg Maintain:
Peak airway pressure < 35 cm H2O
Plateau airway pressure < 25 cm H2O
Positive end-expiratory pressure
5 cm H2OPatients with COPD: no added PEEP
Respiratory rate 12 breaths/min
Maintain normal Paco2; Pa-ETco2 will usually increase 1-3 mm Hg during OLV
Mode Volume or pressure controlled
Pressure control for patients at risk of lung injury (e.g., bullae, pneumonectomy, post lung transplantation)
Suggested ventilatory parameters for OLV
Therapies for Desaturation during One-Lung Ventilation
Severe or precipitous desaturation: Resume two-lung ventilation (if possible).
Gradual desaturation:
1. Ensure that delivered Fio2 is 1.0.
2. Check position of double-lumen tube or blocker with fiberoptic bronchoscopy.
3. Ensure that cardiac output is optimal; decrease volatile anesthetics to < 1 MAC.
4. Apply a recruitment maneuver to the ventilated lung (this will transiently make the hypoxemia worse).
5. Apply PEEP 5 cm H2O to the ventilated lung (except in patients with emphysema).
6. Apply CPAP 1-2 cm H2O to the nonventilated lung (apply a recruitment maneuver to this lung immediately before CPAP).
7. Intermittent reinflation of the nonventilated lung
8. Partial ventilation techniques of the nonventilated lung:
a. Oxygen insufflation b. High-frequency ventilation c. Lobar collapse (using a bronchial blocker)
9. Mechanical restriction of the blood flow to the nonventilated lung
• Respiratory failure
• cardiac herniation
• torsion of a remaining lobe after lobectomy
• dehiscence of a bronchial stump
• hemorrhage from a major vessel
•Post operative complications
Early major
leading cause of postoperative morbidity and mortality
Acute respiratory failure after lung resection is defined as:
◦ acute onset of hypoxemia (PaO2 < 60 mm Hg) or hypercapnia (PaCO2 > 45 mm Hg
◦ use of postoperative mechanical ventilation for more than 24 hours
◦ reintubation for controlled ventilation after extubation
◦ incidence of respiratory failure after lung resection is between 2% and 18%
•Post operative respiratory failure
thoracic epidural analgesia :
prevention of atelectasis and
secondary infections
better preservation of the functional
residual volume
efficient mucociliary clearance
alleviation of the inhibiting
reflexes acting on the
diaphragm
Chest physiotherapy,
incentive spirometry, and
early ambulation are
crucial
provide better oxygenation, treat
infection, and provide vital organ
support without further damaging
the lungs.
• To minimise pulmonary complications postoperatively
•incision (intercostal nerves T4-T6),
•chest drains (intercostal nerves T7-T8),
•mediastinal pleura (vagus nerve, CN X),
•central diaphragmatic pleura (phrenic nerve, C3-C5),
•ipsilateral shoulder (brachial plexus).
multiple sensory afferents :
Hence there is no one analgesic technique that can block all these various pain
afferents, so analgesia should be multimodal.
The ideal post-thoracotomy analgesic technique will include three classes of
drugs: opioids, anti-inflammatory agents, and
local anesthetics.
Post operative analgesia
•Opioids:effective in controlling background pain but the acute pain component associated with cough or movement requires plasma levels that produce sedation and hypoventilation
•NSAIDS :reduce opioid consumption more than 30%.particularly useful treating the ipsilateral shoulder pain
•Ketamine: less respiratory deppression
•Dexmedetomidine: described as an useful adjunct
Systemic Analgesia:
•Intercostal nerve blocks
•Interpleural blocks
•Epidural analgesia
Local Anesthetics/Nerv
e Blocks:
Post op analgesia continues…
Thank you