ANESTHESIA FOR CHRONIC LUNG DISEASE
Preoperative assessmentIntraoperative management
MonitoringLung isolation techniquesPositioningOne lung Ventilation
Postoperative managementPostoperative analgesiaComplications
Preoperative Assessment
AimIdentify patients at high risk Use that risk assessment to stratify
perioperative management and focus resources on the high-risk patients to improve their outcome.
Assessment of Respiratory function
Detailed historyBaseline SpirometryRespiratory MechanicsLung parenchymal functionCardiopulmonary interaction
Respiratory mechanics
For example, after a right lower lobectomy a patient with a preoperative FEV1 (or DLCO) 70% of normal would be expected to have a postoperative
FEV1 = 70% × (1 - 29/100) = 50%
ppoFEV1% = preop FEV1% × (1- %Functional lung tissue removed/100)
Slinger PD, Johnston MR: Preoperative assessment: an anesthesiologist's perspective. Thorac Surg Clin 15:11, 2005.
Ppo FEV1 >40% -Low risk 30-40%- mod risk < 30% - high risk
Cardiopulmonary InteractionMaximum oxygen consumption (Vo2max)
Most useful predictor of post-thoracotomy outcome. Morbidity and mortality is unacceptably high- Vo2max <15 mL/kg/min.Few patients with a Vo2max >20 mL/kg/min have respiratory
complications
Stair climbing5 flights - Vo2max >20 mL/kg/min2 flights - Vo2max of 12 mL/kg/min
6-minute test (6MWT)<2000 ft (610 m) - Vo2max <15 mL/kg/min Patients with a decrease of Spo2 greater than 4% during exercise are at
increased risk for morbidity and mortality.
Preoperative Optimization• Stop smoking, avoid industrial
pollutants • Dilate airways• Loosen secretions
– Airway hydration (humidifier/nebulizer)
– Systemic hydration– Mucolytic and expectorant drugs
• Remove secretions– Postural drainage– Coughing– Chest physiotherapy (percussion
and vibration)
• Adjunct medication– Antibiotics—if purulent
sputum/bronchitis– Antacids, H2 blockers, or PPIs—if
symptomatic reflux.
• Increased education, motivation, and facilitation of postoperative care– Psychological preparation– Preoperative pulmonary care
training• Incentive spirometry• Secretion removal maneuvers
– Preoperative exercise– Weight loss/gain– Stabilize other medical problems
Summary of initial preoperative assessment
All patients: Assess exercise tolerance estimate predicted
postoperative FEV1% discuss postoperative
analgesia discontinue smoking
Patients with predicted postoperative FEV1< 40%: DlCO Ventilation perfusion Scan VO2 max
Cancer patients: consider the “4 Ms”:
mass effects metabolic effects Metastases medications
COPD patients: Arterial blood gas analysis Physiotherapy bronchodilators
Increased renal risk: Measure creatinine and blood
urea nitrogen
Intraoperative Monitoring
• Oxygenation• Capnometry• Arterial blood pressure• CVP• Pulmonary artery pressure• Fibreoptic bronchoscopy• Urine output• Temperature
Lung Isolation Techniques
• Double lumen tube• Bronchial blocker– Arndt – Cohen– Fuji
• Univent tube• Endobronchial tube• Endotracheal tube advanced into bronchus
Double lumen tube Carlens tube Robertshaw tube
Advantages Quickest to place successfully Repositioning rarely required Bronchoscopy to isolated lung Suction to isolated lung CPAP easily added Can alternate OLV to either lung
easily Placement still possible if
bronchoscopy not available
Disadvantages Size selection more difficult Difficult to place in patients
with difficult airways or abnormal tracheas
Not optimal for postoperative ventilation
Potential laryngeal trauma Potential bronchial trauma
Lateral decubitus position for thoracotomy
Positioning• Position Change–W/f hypotension– Secure all lines and monitors –Make an initial “head-to-toe” survey – Check oxygenation, ventilation,
hemodynamics, lines, monitors, and potential nerve injuries.
– Reassess after repositioning– Recheck Endobronchial tube/blocker position
and the adequacy of ventilation by auscultation and fiberoptic bronchoscopy after repositioning.
“Head-to-Toe” Survey • Dependent eye • Dependent ear pinna • Cervical spine in line with thoracic spine• Dependent arm: – Brachial plexus– Circulation
• Nondependent arm: – Brachial plexus– Circulation
• Dependent and nondependent suprascapular nerves • Nondependent leg: sciatic nerve • Dependent leg:– Peroneal nerve – Circulation
Treatment of Hypoxemia• Severe or precipitous desaturation:
– Resume two-lung ventilation (if possible).• Gradual desaturation:
– Ensure that delivered FIO2 is 1.0– Check position of DLT or blocker with fiberoptic bronchoscopy– Ensure cardiac output is optimal; decrease volatile anesthetics to < 1
MAC– Apply a recruitment maneuver to the ventilated lung – Apply PEEP 5 cm H2O to the ventilated lung – Apply CPAP 1-2 cm H2O to the nonventilated lung (apply a – recruitment maneuver to this lung immediately before CPAP)– Intermittent reinflation of the nonventilated lung – Partial ventilation techniques of the nonventilated lung:
• Oxygen insufflation • High-frequency ventilation • Lobar collapse (using a bronchial blocker)
– Mechanical restriction of the blood flow to the nonventilated lung
Ventilation StrategiesParameter Suggested Guidelines/ Exceptions
Tidal volume 5-6 mL/kgMaintain:
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)
Postoperative mangement- Analgesia
• Systemic Analgesia – Opioids– Nonsteroidal Anti-inflammatory Drugs– Ketamine– Dexmedetomidine
• Local Anesthetics/Nerve Blocks – Intercostal Nerve Blocks– Intrapleural Analgesia– Epidural Analgesia– Paravertebral Block
Thoracic Epidural Analgesia
• Better preservation of the functional residual volume
• Efficient mucociliary clearance• Alleviation of the inhibiting reflexes acting
on the diaphragm • prevention of atelectasis and secondary
infections
Postoperative Complications
• Early Major Complications– Torsion of a remaining lobe after lobectomy– Dehiscence of a bronchial stump– Hemorrhage from a major vessel– Respiratory Failure– Cardiac Herniation
Anaesthetic management of bronchopleural fistula
Bronchopleural fistulaCommunication from major bronchus to pleural spaceCommonly associated with pneumonectomy, trauma, abscess or empyemaRelevant complications
Pus may contaminate other lung-associated injuries with trauma
SurgeryUsually semi-electiveResuturing of bronchial stump, muscle flap to stump, drainage of abscess
High risk surgery requiring GA and one-lung ventilation
If incidental surgery, GA may be avoided, regional preferred
Positioning still important to avoid soiling
PatientCommonly debilitated, may have coexistent
medical problemsRespiratory function assessed
Clinical, spirometry, ABGsRoutine assessment for thoracic surgery
Consideration of epidural
Decision to proceedRespiratory function optimizedChest drain inserted to avoid tension
pneumothorax and drain pleural collection
InductionObjectives
Maintain oxygenation and ventilation, avoid tension pneumothorax
Avoid soiling good lungProtection of lung requires DLT, bronchial lumen to good
sideSmall leak without infection may be manageable with
single-lumen ETTPaediatric patients are typically too small for DLT or
FOB --> blocker or endobronchial intubationFistula reduces effectiveness of mask IPPV, so
spontaneous ventilation Ideally awake DLT intubation
Topical local anaesthetic to airway Position head-up and bad side down Sedation for intubation
Alternatively spontaneously ventilating GA with DLT insertion when deep
Verification of DLT position with differential ventilation or FOB
MaintenanceIPPV to healthy lungLung with fistula may benefit from small VT
ventilation or CPAP below critical pressure for fistula or HFJV
EmergenceAvoid high airway pressures if fistula has been
repaired Hand ventilation or SIMV
PostoperativeEpidural analgesiaHDU monitoring post-op
High incidence of arrhythmia post-thoracotomy
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