Thoracic Anesthesia Flashcards
When are thoracic surgeries indicated?
- Malignancy
- pulmonary
- esophageal
- mediastinal
- Infections
- empyema
- lung absess
- End stage lung disease
- lung volume reduction
- lung transplantation
- ***An operable person is someone who can tolerate the proposed resection with acceptable risk
What are the common complications?
What are the risk factors for complications?
- Complications
- 3-4%mortality
- atelectasis
- pneumonia
- respiratory failure
- cardiac (arrhythmia and ischemia
- Risk factors
- advanced age
- poor general health
- COPD
- BMI > 30
- low FEV1
- low PPO (predictive post-op function
Small cell carcinoma:
prognosis?
treatment?
How does it originate?
- Poor prognosis, usually not resectable and metastatic on presentation
- survival is about 3 months after diagnosis
- Usually not candidates for surgery
- chemo/radiation
- Neuroendocrine origin
- Lambert-Eaton Myasthenic syndrome
- SIADH- hyponatremia
- Hypercortisolism
What is Lambert-Eaton Myasthenic Syndrome?
- paraneoplastic syndrome caused by impaired release of acetylcholine from nerve terminals
- presents as proximallower limb weakness and fatigability that may temporarily improve with exercise
- Pts are extremely sensitive to nondepolarizing muscle relaxants
- Respond poorly to acetylcholinesterase inhibitors such as neotigmine
- diaphragm and muscles of respiration may be involved.
- **Thoracic epidural can be used in these pts without complication
- Neuromuscular fxn may improve after resection of lung cancer
Non-Small cell lung cancer
types?
prognosis?
- Types:
- squamous cell
- adenocarcinoma
- **Can have big masses->SVC syndrome
- Prognosis is variable; cancer is slow growing
- surgery usually considered
- <50% survive 5 years
What are the anesthetic considerations for different types of lung cancer? (table)
Squamous cell
Adenocarcinoma
Large cell
Small cell
Carcinoid
- **of note, SCLC carcinoid tumors are the most malignant form of carcinoid tumors
- be prepared to deal with severe hypotension that will not respond to usual drugs
- be prepared to treat with octreotide or somatostatin
What should be included in your pre-op assessment for all thoracic surgery patients?
What are your anesthetic considerations for pts with lung cancer?
What are the problems with pts how took these medications?
Bleomycin?
doxorubicin?
cisplatin?
- Bleomycin- can have oxygen toxicity, keep O2 low
- Doxorubicin- can have cardiac toxicity
- Cisplatin- can have renal toxicity
What types of symptoms might a pt with a lung tumor have?
- Bronchopulmonary
- involvement of the lung: cough, dyspnea
- Extrapulmonary intrathoracic- tumor growth beyond the confines of the lung
- pleural effusion, chest wall pain, dysphagia
- Extrathoracic Metastatic- tumor spread outside the thorax
- brain, skeletal, kidney, lymph, skin
- Extrathoracic Non-metastatic- paraneoplastic syndrome
- endocrine or endocrine -like syndrome, Cushings disease, hypercalcemia, SIADH, Lambert-Eaton
- Non-specific
- weight loss, anemia, anorexia, malaise, vague cold-like symptoms
What should be included on the pre-op physical assessment?
- Physical exam: inspection, palpation, auscultation, percussion
- Exercise tolerance: primary determinant of outcome in older pts
- Laboratory tests:
- routine labs
- sputum gram stain
- culture and cytology
- LFTs
- ABGs
- Chest radiograph
- PFTs
- pre-op bronchoscope
Which CXR findings have specific anesthesia implications?
(6)
- Tracheal deviation and obstuction-
- difficulty with intubation or ventilation
- Mediastinal mass-
- difficulty with intubation and ventilation
- SVC syndrome compression of PA
- Pleural effusions
- decreased VC and FRC
- Cardiac enlargement
- susceptible to depressant effects of the heart
- Bullous cyst
- prone to rupture
- Parenchymal reticulation consolidation
- prone to atelectasis edema
Wha is the three legged stool of pre-thoracotomy respiratory assessment? (chart)
Who needs PFTs?
- Pts with evidence of COPD
- smokers with hx of persistant cough
- Pts with hx of wheezing or DOE
- Restrictive lung dx: chest wall or spinal deformities
- morbidly obese
- upper abdominal surgery candidates
- thoracic surgery candidates
- pts >70 yrs
What are the different lung volumes and capacities?
(chart)
- TV- volume inhaled and exhaled with normal breath
- IRV- volume that can be maximally inhaled beyond nml TV
- ERV- maximal volume of air that can be exhaled beyond nml TV
- RV- volume of air that remains in the lung after maximal expiration
- TLC- sum or IRV, TV, ERV, and RV
- VC- sum of IRV, TV, and ERV
- IC- sum of IRV and TV
- FRC- volume of air in the lung at the end of a normal expiration and is the sum of RV and ERV
What are the different phases of PFT testing?
- Phase I- Whole lung test
- detect abnormalities of gas exchange
- detect abnormalities of lung size, chest wall, mechanical aspects of ventilation
- Phase II- Split lung testing
- details the fxn of each lung separately
- Phase III- Post0op condition of pt is simulated via temporary balloon occlusion of the majory pulmonary artery on that side
Vital capacity:
What is it?
What is normal?
What decreases VC?
- Vital capacity is deep maximal inspiration followed by maximal exhalation “slow and relaxed”
- VC = IRV + TV + ERV or VC = TLC - RV
- Normal is >/= 80% of predicted value (based on height, age, and gender)
- VC is decreased:
- going from sitting to supine position
- restrictive lung disease
- loss of distensible lung tissue
- whenever maximal inspiration or axhalation is not achieved
Forced Vital Capacity:
What is it?
How is it interpreted?
- Maximal inspiration followed by rapid forceful exhalation
- reflects flow resistance in the airway
- measured as volume/time
- Interpretation of % predicted:
- 80-120% normal
- 70-79% mild
- 50-69% moderate
- <50% severe
- ** little to no difference btwn VC and FVC in nml pts
- low FVC signifies airtrapping or small airway collapse
FEV1
What is it?
Normal?
- FEV1 is the forced expiratory volume in the first second of the FVC measurement
- Normal is 75-80% of FVC (declines with age)
-
Most valid test for postop respiratory complications is ppoFEV1
- ppoFEV1 %= preop FEV1 x (1-% functional lung tissue removed/100)
What are the lung lobe segments used to calculate ppoFEV1?
(pic)
How is the FEV1/FVC ratio interpreted?
How does this test differ between restrictive and obstructive disease?
- >75% = normal
- 60-70% = mild
- 50-59% = moderate
- <49% = severe obstruction
- ***FEV1/FVC ratio is normal in restrictive disease because both the FEV1 and FVC decrease, whereas in obstructive disease the ratio is usually low because the FEV1 is markedly decreased
What is FEF25-5%?
How is it interpreted?
- Forced expiratory flow 25-75%
- mean forced expiratory flow during middle of FVC
- may reflect effort independent expiration and the status of the small airways
- sensitive in early stages of obstructive disease
- more reliable than FEV1/FVC ratio
- Interpretation of % precicted:
- >60% normal
- 40-60% mild
- 20-40% moderate
- <10% severe obstruction
What would you expect to see for your FEV1, FVC, and FEV1/FVC values in:
Obstructive disease
restrive disease
muscle weakness
What is MVV?
- Maximum voluntary ventilation is the largest volume that can be breathed per minute by voluntary effort
- requires high rate of air flow, changes in aw resistance alter MVV
- MVV is reduced in obstructive disease, normal in restrictive disease
- MVV correlates to FEV1
- FEV1 x 35 ≈ MVV
- Normal is >50% of predicted values
What factors affect MVV?
- Patient effort (motivation, coordination)
- Elastic properties of the lung
- chest wall abnormalities
- Respiratory muscle strength
What is closing volume?
When do you see it elevated?
- Closing volume is the lung volume at which airways begin to close or stop contributing to the expired gas
- In the sitting position CV for health ppl is about 15-20% of VC
- CV is elevated in smokers!
- reflects the loss of elastic recoil and/or small airway pathology
PFTs in restrictive and obstructive lung disease: (table)
definition
FVC
FEV1
FEV1/FVC
FEF25-75%
FRC
TLC
What is a significant result regarding the maximum oxygen consumption (VO2max) during exercise testing?
What is DCLO?
- Decrease of 4% during exercise is considered high risk
- Pre-op VO2max < 15 ml/kg/min is high risk
- DLCO (diffusing capacity) is the ability of the lung to perform gas exchange (pt inhales CO)
- <40% of postop predicted value is high risk
- **DLCO is a better predictor of complications than FEV1 in pts who have received chemotherapy
How can we estimate the VO2max?
- 6 minute walk test in meters / 30
- ex. 6 minute walk of 450 meters/30 = 15 ml/kg/min
- Pts with decrease in Spo2 > 4% during exercise are also at increased risk
