AP 2 Test 1 Flashcards
How long must a patient be ventilator dependent to be classified as having respiratory failure
Greater than 48 hours after surgery
What is the most important risk factor for post-op pulmonary complication?
High risk surgical site
The risk of pulmonary complications increase as the surgical incision gets closer to what muscle?
The diaphragm
What procedures are high risk for pulmonary complications post operatively?
Aortic, thoracic, upper abdominal procedures
Other than the surgical site, what are other surgical risks for post-op pulmonary problems? (4)
Emergency surgery, surgery greater than 3 hours, general anesthesia, multiple transfusions
What are the 2 major patient related risk factors for post-op pulmonary complications?
Increasing age (over 60) and increasing ASA status
Other than age and ASA status, what other patient risk factors for post-op pulmonary complications are supported by good evidence? (3)
CHF, COPD, functional dependency
What patient related risk factors for post-op pulmonary complications are supported by fair evidence? (4)
Unintentional weight loss, smoking cigarettes, alcohol use, abnormal chest CT
What 4 risk factors have been proved to not be a risk factor for post-op pulmonary complications?
Controlled asthma, obesity, hip surgery, GU/gynecologic surgery
Which of the following have recently been identified as risk factors for post-op pulmonary complications?
A. Epidural Anesthesia B. Insulin-treated diabetes C. Obstructive sleep apnea D. Immobility E. Pulmonary Hypertension
C and E
In patients with OSA, how many desaturations per hour predicted high risk of pulmonary complications?
Greater than 5 desaturations during nocturnal oximetry
What was the percentage of respiratory failures in patients with pulmonary hypertension?
20-28%
What neuraxial anesthesia procedure has been proved to reduce post-op pulmonary complications?
Post-up thoracic epidural anesthesia - reduced complications by 1/3 to 1/2
What 2 strategies for risk reduction of pulmonary complications post up are supported by good evidence?
Post-op lung expansion modalities and post-op epidural anesthesia
What 5 diseases are classified as obstructive lung diseases?
Emphysema, cystic fibrosis, chronic bronchitis, asthma, COPD
How does obstructive airway disease affect airway resistance?
Increases resistance
How does restrictive airway disease affect airway compliance?
Decreases compliance
How does the diameter of the airways affect resistance
Smaller the diameter, less flow. Larger diameter, more flow
If airway diameter is reduced by half, how is resistance affected
Increases by a factor of 16
If you change the density of a gas, you’re essentially changing what?
The driving pressure of the gas
When is heliox most commonly used?
When the large airways are narrowed due to upper airway obstructions such as tumors, foreign bodies, or vocal cord dysfunction
Patients with what 3 comorbidities usually have “medium” upper airways?
Croup, asthma, copd
Where does laminar flow occur in the airways?
In the smaller airways
Where does turbulent flow occur in the airway?
Nose, mouth, larger airways
What happens to resistance when lung volume is reduced
Airway resistance rises rapidly
What may happen to the smaller airways at very low lung volumes
They may completely close
What size of bronchi have the most resistance?
Mid-sized bronchi
Obstructive vs Restrictive Diseases - what anatomy is affected in each?
Obstructive: airways
Restrictive: lung tissue or thorax
Obstructive vs Restrictive Diseases - what phase of breathing does the difficulty occur?
Obstructive - expiration
Restrictive - inspiration
Obstructive vs Restrictive Diseases - what does the pulmonary function test indicate in each?
Obstructive - decreased airway flow rates
Restrictive - decreased airway flow rates or capacity
Do patients with obstructive lung diseases have trouble inspiring or expiring?
Expiring
What is the primary problem in asthma?
Airway inflammation and hyper-irritability
What is presented clinically in patients with asthma?
Episodic attacks of dyspnea, coughing, wheezing
What are the causes of airway obstruction in patients with asthma?
Bronchial smooth muscle contraction, edema, increased secretions
What types of things can precipitate airway obstruction in patients with asthma?
Airborne substances, ingestion, exercise, emotional excitement, viral infections
What medications/agents can trigger an asthma attack in asthmatic patients?
Aspirin, NSAIDS, sulfiting agents, yellow dye (tartrazine)
Upon being exposed to an asthma triggering agent, what occurs?
Release of inflammatory mediators
What inflammatory mediators are released when asthma is triggered? [Hey, taylor likes peanut butter]
Histamine, tryptase, leukotrienes, prostaglandins, bradykinin
What mediators are involved in the early-phase asthmatic response, and what do they cause?
DIRECT mediators, cause acute bronchoconstriction
What mediators are involved in the late-phase asthmatic response, what white blood cells are involved, and what is the result?
INDIRECT mediators direct EOSINOPHILS and NEUTROPHILS to the airway, this causes epithelial damage, edema, extra mucus secretion, and hyper responsiveness
What division of the nervous system plays a major role in maintaining normal bronchial tone, and is overactive in patients with asthma?
Parasympathetic
Vagal activation can be triggered by what substances/actions?
Histamine, noxious stimuli, cold air, irritants, instrumentation
What does reflex vagal activation result in?
Bronchoconstriction
What mediates the bronchoconstriction cause by reflex vagal activation?
Intracellular cyclic GMP
In acute asthma attacks, residual volume increases by ___% and FRC increases by ___%
400%, 100%
In acute asthma attacks, the number of alveoli with low V/Q ratio increases, resulting in what?
Hypoxemia
In acute asthma attacks, increased breathing leads to what?
Hypocapnia
Why should you worry about a normal or high PaCO2 in patients with acute asthma attacks?
This indicates the patient can no longer maintain work of breathing, respiratory failure is impending
As asthma attacks resolve, airway resistance is first normalized in what region of the airways?
The larger airways
What classes of drugs are used to treat asthma (6) [Betty Met Gino At Lowe’s Monday]
Beta-adrenergic agonists, methylxanthines, glucocorticoids, anticholinergics, leukotriene blockers, mast cell stabilizing agents
Why are methylxanthines not used frequently to treat asthma?
They have a narrow therapeutic range so patients often complain of PONV and anxiety
What is the only available IV preparation of methylxanthines to treat asthma?
Aminophylline
What effects do glucocorticoids cause that helps in the treatment of asthma?
Anti-inflammatory and membrane stabilizing effects
Drugs such as beclomethasone, triamcinolone, flutasone, and budesonide are used as maintenance therapy for what obstructive lung disease?
Asthma - used in maintenance dosed inhalers
What drugs are given IV for severe asthma attacks
Hydrocortisone/methylprednisolone
Why are anticholinergics used to treat asthma
They produce bronchodilation
What drug, that acts like atropine, can be given by MDI or aerosol to treat asthma
Ipratropium
What class of drugs PREVENT asthma?
Inhaled corticosteroids
What class of drugs CONTROL asthma?
Long acting beta 2 agonists
What class of drugs RELIEVE asthma?
Short acting beta 2 agonists
What special considerations should be assessed pre-operatively when going over the history of a patient with asthma
Recent course of the disease, whether the patient has been hospitalized for an attack
What preoperative considerations would NOT be helpful in a patient with a history of asthma? A) Clinical history B) Current state of the disease C) CBC test D) Xray E) PFTs (pulmonary function tests
CBC tests - the other options should be considered
How should you treat an active bronchospasm for emergent surgery?
Give oxygen, aerosol beta 2 agonists, give IV glucocorticoids
From an arterial blood gas sample, what would indicate an asthma attack
Hypoxemia, hypocapnia
What common drugs used perioperatively by anesthetists can trigger a bronchospasm due to histamine release?
Sux, morphine, demerol
What might you consider during emergence in a patient with asthma?
Deep extubation or a lidocaine bolus
What 2 diseases are encompassed in COPD?
Chronic bronchitis and emphysema
The prevalence of COPD increases with what?
Age
COPD is mainly associated with what habit?
Smoking
What gender is most at risk for COPD?
Men - up to 20% of men have COPD
What produces the airway obstruction that causes chronic bronchitis
Secretions for enlarged bronchial glands, mucosal edema
How does chronic bronchitis affect residual volume
Increases residual volume
What is caused by the prominent intrapulmonary shunting that occurs with chronic bronchitis
Hypoxemia
What 3 things can hypoxemia lead to if left untreated?
Erythrocytosis, pulmonary hypertension, RV failure
What gas drives ventilation in patients with chronic bronchitis?
Oxygen
Why do you want to limit FiO2 in patients with chronic bronchitis?
Since their ventilatory drive is based on O2 instead of CO2, increased oxygen could reduce their drive to breath
What disease causes “Blue Bloater” syndrome, and why does it occur?
Chronic bronchitis - their FRC increases and causes the bloating, and the severe hypoxemia causes the bluish tint
How is emphysema diagnosed?
By CT of the chest showing irreversible enlargement of the airways distal to the terminal bronchioles and destruction of alveolar septa
Although emphysema is mostly associated with smoking, it can also be due to a deficiency in what?
Alpha 1-antitrypsin
In patients with emphysema, what is caused by the loss of dynamic recoil in smaller airways
Airway collapse during exhalation
What is caused by the destruction of pulmonary capillaries in patients with emphysema
Decreased carbon monoxide diffusion capacity, leads to pulmonary hypertension
What is a prominent feature of large cystic bullae/blebs in patients with emphysema
Increased dead space
What lung volumes are increased in patients with emphysema
Residual volume, total lung capacity, FRC
What disease causes the “Pink Puffer” syndrome and why does it occur?
Emphysema - vascular beds are destroyed so the body hyperventilates to compensate (puffing), and these patients have less V/Q mismatch than blue bloaters, causing a pink appearance
How could you use a patient’s PaCO2 to decipher if they had chronic bronchitis or emphysema
Patients with CB will have an elevated PaCO2 over 40mmhg, whereas patients with emphysema will have normal PaCO2
Which disease encompassed under COPD is associated with copious sputum production
Chronic bronchitis
Which disease encompassed under COPD is associated with elevated hematocrit
Chronic bronchitis
What is the most important intervention for COPD treatment
Tell the patient to stop smoking
What drug therapy is useful in COPD treatment
Bronchodilator therapy with b2 agonists, glucocorticoids, ipratropium
How is cor pulmonale (right ventricular failure) prevented in the treatment of COPD
Diuretics are used to control peripheral edema
What anesthetic technique is best to use for COPD patients and why?
Regional, minimizes the use of airway instrumentation
How should the I:E ratio be adjusted for patients with COPD
Increase expiratory time
What gas should be avoided in patients with bullae and pulmonary htn?
Nitrous oxide
How should you adjust tidal volumes in patients with COPD
Small to moderate tidal volumes (6cc/kg)
Patients with pulmonary bullae have a high risk of developing what?
Pneumothorax
What extubation technique is usually best for patients with COPD?
Deep - decreases risk of reflex bronchospasm
Patients with FEV1 less than __% are most likely to require post-op ventilation
50%
For every 10% increase in FiO2, how much does PaO2 increase?
50-60mmHg
What is indicated by a decreased pH and increase pCO2?
Respiratory acidosis
What is the normal CO2 content?
22-26mEg/L
What premedications could be considered in a patient with asthma and COPD?
Albuterol, versed, benadryl, glycopyrrolate
What airway device should be used in a patient with asthma and COPD?
LMA because it requires less instrumentation
What volatile agent should be used in a patient with asthma and COPD?
Sevo
What would you NOT use to control pain in a patient with asthma and COPD?
NSAIDs like toradol, ofirmev, etc
What is the limit on FiO2 you should use in a patient with asthma and COPD?
40%
What cavity sits above the diaphragm, and what structures does it hold?
Thoracic cavity - contains heart, trachea, esophagus, thymus, lungs
What cavity sits below the diaphragm, and what major structures does it hold?
Abdominopelvic cavity - contains liver, pancreas, GI tract, spleen, GU tract
Where does the upper respiratory tract begin and end
Mouth to larynx
Where does the lower respiratory tract being and end
Larynx to alveoli
What type of flow occurs in the upper airways
Convection
Where do the conducting airways begin and end
Trachea to terminal bronchioles
What part of the upper airway is most vulnerable to foreign particles?
Right main stem
What are the 3 basic functions of the upper respiratory tract?
Warm, humidify, filter
What receptors are responsible for the sympathetic innervation of the conducting airways?
B2 receptors
What receptors are responsible for the parasympathetic innervation of the conducting airways?
Muscarinic receptors
Which receptors lead to constriction of the smooth muscle lining the airways?
Muscarinic receptors of the parasympathetic ns
Where does the respiratory zone of the airways begin and end?
Respiratory bronchioles to alveoli
What is the function of the respiratory zone of the airways
Gas exchange
What is the function of alveolar type I cells?
Help establish the structure of the alveoli
What is the function of alveolar type II cells?
Secrete surfactant
What is the function of surfactant
Lowers surface tension on the alveoli to help equalize pressure and keep alveoli open
How much blood does each ventricle pump per minute
5.5 L/min
Does the pulmonary circulation have low or high resistance and pressure?
Low resistance, low pressure
What 2 things are the main determinants of pulmonary blood flow?
Gravity and HPV (hypoxic vasoconstriction)
Gravity is responsible for uneven blood flow in the lungs. What is the blood flow like when a patient is supine?
Uniform
What is blood flow distribution like when a patient is standing?
Lowest flow at the apex, highest at the base of the lung
In Zone 1 of the lung, which pressure is highest and how is blood flow to the area?
Alveolar pressure is highest which compresses capillaries and decreases blood flow
In Zone 2 of the lung, which pressure is highest and why?
Arterial pressure is highest and progressively increases as you go down the lung because of hydrostatic pressure and gravity
In Zone 3, which pressure is highest and which is lowest?
Arterial pressure is highest, alveolar pressure is lowest
How does hypoxia affect blood vessels?
It causes vasoconstriction
What is inspiratory reserve volume?
The extra volume the comes with a forced inspiration
What is expiratory reserve volume?
Extra volume that comes out with a forced expiration
What is residual volume?
Volume that is always left in the lungs, even after forced expiration
Which volume cannot be measured with spirometry?
Residual volume
What 2 lung volumes make up inspiratory capacity?
Tidal volume and inspiratory reserve volume
What 2 lung volumes make up functional residual capacity?
Expiratory reserve volume and residual volume
What is the definition of functional residual capacity
Volume remaining in the lungs after an expired tidal volume
What is the definition of vital capacity
The most volume you can ever expire, with forced inspiration and forced expiration - maximal breath
What 3 lung volumes make up vital capacity
Inspiratory reserve, tidal volume, expiratory reserve
What populations have increased vital capacities?
Males, large body sizes, physically conditioned
What causes vital capacity to decrease over time?
Age
What is dead space
Volume in the airways that does not participate in gas exchange
What is anatomic dead space and how much volume does it hold
Volume of the conducting airways, holds about 150ml
What is physiologic dead space
Volume of the lungs that does not participate in gas exchange
What creates functional dead space
V/Q mismatch
In normal patients, how does physiologic dead space volumes compare to anatomic dead space volumes
The 2 volumes are equal
What muscles are involved in inspiration
Diaphragm, external intercostals, accessory muscles
What is the intrapleural space
Space between the visceral and parietal pleura
What are the 4 parts of the pleura lining the thoracic cavity?
Cervical, costal, diaphragmatic, mediastinal
What 2 forces hold the thoracic wall and lungs in close opposition?
The intrapleural fluid cohesiveness and the negative intrapleural pressure
What is transmural pressure, and is it normally negative or positive?
Difference between alveolar and intrapleural pressure, normally negative
What 2 things cause lung compliance to increase?
Emphysema, age
What 3 things cause lung compliance to decrease?
Fibrosis, lack of surfactant, increases in pulmonary venous pressure
What is alveoli interdependence
If alveoli start to collapse, surrounding alveoli are stretched and then recoil, which exerts expanding forces to open the collapsing alveoli
What forces help keep alveoli open?
Transmural pressure gradient, surfactant, interdependence
What forces promote alveolar collapse?
Elasticity of pulmonary connective tissue, surface tension on alveoli
How are elasticity and compliance related
Elasticity is the inverse of compliance
What is a pneumothorax
Air in the pleural space
How does a pneumothorax affect lung pressures
It abolishes the transmural pressure gradient
What happens to the lungs when transmural pressure is abolished
They collapse
What 3 main factors affect airway resistance
Bronchial smooth muscle, lung volume, viscosity/density of inspired gas
What gas laws affect gas exchange in the alveoli
Dalton’s law, Fick’s law of diffusion, Boyle’s law
What 2 main ways is O2 transported throughout the body
Dissolved in solution or bound to hemoglobin
What is each molecule of hemoglobin made up
4 polypeptide chains (2 alpha, 2 beta) and 4 hemes
What is oxyhemoglobin
Ferrous iron plus O2
What is deoxyhemoglobin
Ferrous iron, no O2
What does the oxygen dissociation curve depict?
The effect of pO2 on unloading/loading
What does a shift to the right on an oxygen dissociation curve mean?
That hemoglobin has a reduced affinity to bind oxygen, meaning oxygen is unloaded at tissues
What things can cause the O2 curve to shift right
Increased temperature, increased 2-3 DPG, increased H+ (low pH)
What does a shift to the left on an oxygen dissociation curve mean?
Affinity of hemoglobin to bind oxygen increases
What things can cause O2 curve to shift left
Decreased temp, decreased 2-3 DPG, decreased H+ (high pH), carbon monoxide
Which direction does smoking cause the O2 dissociation curve to shift
Left
What 3 forms is CO2 carried in
Bicarbonate, dissolved, carbaminohemoglobin
How is most CO2 in the body transported
Bicarbonate ion
What is the “chloride shift”
Bicarbonate leaves red blood cells and diffuses into plasma, making the rbc become more positive and attract a chloride ion in
Where is the chloride shift reversed?
In the pulmonary capillaries
Where are the respiratory centers located in the brain?
Medulla oblongata and pons
What 2 cranial nerves control sensory input involved in breathing?
Vagus, glossopharyngeal
What nerve controls motor output involved in breathing?
Phrenic
What are central chemoreceptors sensitive to and how do they affect breathing
Sensitive to decreases in the pH of CSF, cause increase in breathing
What molecules/ions in the body do central chemoreceptors detect
CO2 and H+
Where are peripheral chemoreceptors located
Carotid and aortic bodies
What molecule do peripheral chemoreceptors respond to
Low levels of O2
How low must PaO2 get before peripheral chemoreceptors respond
Below 60
Where are lung stretch receptors
Smooth muscles of the airway
What is the Hering-Breurer Reflex
Dissension of the airways causes decrease in breathing frequency
Where are irritant receptors located and how are they stimulated
In airway epithelial cells, stimulated by noxious stimuli - dust/pollen
Where are J receptors located and how do they affect breathing
Located in walls of alveoli, engorgement of capillaries causes rapid breathing
How are joint/muscle receptors activated
During movement of limbs, exercise
With Restrictive Lung Diseases, what aspect of lung function is affected and what aspects remain normal?
Lung expansion is restricted, but airway resistance and expiratory flow rates are normal
How are lung volumes and compliance changed in a patient with a restrictive lung disease?
Decreased lung volumes, decreased compliance
Restrictive lung diseases include diseases affecting what 4 parts of the body?
1) Lung parenchyma
2) Pleura
3) Chest wall
4) Neuromuscular system
Low lung volumes, seen in patients with restrictive lung disease, can lead to what 3 events?
Atelectasis, V/Q mismatch, and hypoxemia
In patients with a restrictive lung disease, what 2 changes in lung mechanics causes especially rapid desaturation?
They have decreased oxygen diffusion and a reduced FRC
What problems can restrictive lung disease lead to if it becomes severe enough?
Pulmonary hypertension and cor pulmonale (pulmonary heart disease, right ventricle enlargement and failure)
How does the body of a patient with restrictive lung disease compensate to maintain minute ventilation?
Increase respiratory rate - rapid, shallow breathing
What is the gold standard definition of Restrictive Lung Disease
A spectrum of disorders characterized by a decrease in Total Lung Capacity
What is Total Lung Capacity, and how much must it be affected to be considered a severe problem?
It is the maximum volume of air in lungs - including vital capacity and residual volume. A reduction greater than 50% is considered severe
What 2 methods are used to measure a person’s total lung capacity?
1) Helium dilution
2) Body plethysmography
How are FEV1, FVC, and FEV1/FVC values changed in patients with RLD?
FVC (forced vital capacity) and FEV1 (forced expiratory volume in 1 second) are decreased, but the FEV1/FVC ratio is normal
What is affected in Intrinsic Restrictive Lung Diseases?
Pulmonary parenchyma or airspace (i.e. lung problem)
What is affected in Extrinsic Restrictive Lung Diseases?
Lung expansion is impaired but lungs are normal (i.e. extrapulmonary problem)
RLDs are subcategorized into what 2 etiologies?
Acute and chronic
How are acute intrinsic RLDs defined?
Reduced lung compliance due to an increase in extravascular lung water, either from an increase in pulmonary capillary pressure or increase in pulmonary capillary permeability
What are some examples of acute intrinsic RLDs?
ARDS, aspiration pneumonitis, infectious pneumonia, LV failure, many variations of pulmonary edema
Should a patient with an acute intrinsic RLD have an elective surgery?
No, it should be delayed until cardiorespiratory function has been treated and optimized
How should you set the ventilator to provide lung protective ventilation to your patient with an acute intrinsic RLD?
Low tidal volume, high respiratory rate, peak inspiratory pressures below 30, PEEP
What extra monitor should be included in your intraop care of a patient with an acute intrinsic RLD?
Invasive hemodynamic monitoring
What is Acute Respiratory Distress Syndrome?
An acute inflammatory response to the lung resulting in noncardiogenic pulmonary edema
What are the 4 criteria for diagnosing a patient with ARDS?
Acute onset, bilateral infiltrates on chest X ray, PaO2/FiO2 less than 200, pcwp less than 18
What is the purpose of the ARDSNet Ventilatory Protocol?
Avoids volutrauma and barotrauma in patients with ARDS
List the appropriate values set by the ARDSNet Ventilatory Protocol for each of the following: Tidal Volume: PEEP: SpO2: PaO2: Plateau pressures: Peak pressures:
TV: 6cc/kg PEEP: 5mmHg SpO2: 88-95% PaO2: 55-80 Plateau pressures: Below 30mmhg Peak pressures: below 35mmhg
Why do with optimize FiO2/PEEP in patients with ARDS?
To reduce O2 toxicity
To maintain pH in patients with ARDS, we employ _______ ________
Permissive hypercapnia
What is the goal pH during permissive hypercapnia of patients with ARDS, and what is the lowest allowable pH?
Goal is 7.3-7.45, lowest pH is 7.15
What diseases are categorized as Chronic Intrinsic RLD?
Interstitial lung diseases
What are the characteristics of interstitial lung diseases?
Insidious onset, chronic inflammation of alveolar walls and tissue, progressive pulmonary fibrosis
In ILDs, what does the chronic interstitial inflammation lead to?
Fibroblast activation –> pulmonary fibrosis –> decreased elasticity
What are the symptoms of patients with ILDs?
Dyspnea, dry cough, tachypnea
What appears on a chest x ray of a patient with an ILD?
“Ground glass” appearance, prominent reticulonodular markings, honeycomb appearance
What is a typical arterial blood gas in a patient with an ILD?
Hypoxemia, normocarbia
What is found on a physical exam that is consistent with ILD?
Dry crackles at lung base, clubbing, signs of RV failure such as ascites, hepatomegaly, anasarca
What is characteristic of pulmonary function tests of patients with an ILD?
Decreased FVC, normal FEV1/FVC, decreased DLCO
What kinds of treatments are available for patients with an interstitial lung disease?
Glucocorticoid, immunosuppressive, or supplemental oxygen therapy
What is Sarcoidosis?
Systemic granulomatous disease that involves many tissues but has predilection for lung fibrosis and thoracic lymph nodes
What anatomy is affected in patients with acute extrinsic RLD?
Pleura or mediastinum
What are some examples of acute extrinsic RLDs?
Pleural effusion, pneumothorax, pneumomediastinum
What causes chronic extrinsic RLDs?
Restriction of lung expansion by chest wall, diaphragm, abdominal contents, or neuromuscular disorders
What are the 3 main causes of reduced lung expansion in patients with chronic extrinsic RLDs?
Obesity, pregnancy, ascites
What airway problems occur in obese patients?
Difficult mask ventilation, difficult intubation
What chest wall abnormalities can cause reduced lung expansion in patients with chronic extrinsic RLDs?
Kyphoscoliosis, sternal deformities, ankylosing spondylitis, flail chest
A Cobb angle greater than ___ degrees is usually associated with respiratory failure
100 degrees
What is scoliosis
Lateral curvature of the spine
What is kyphosis
Anterior flexion of the spine
What neuromuscular disorders cause reduced lung expansion in patients with chronic extrinsic RLDs?
Spinal cord transection, Guillain-Barr, disorders of neuromuscular transmission (myasthenia gravis, ALS), muscular dystrophy
Patients with chronic extrinsic RLDs due to a neuromuscular disorder have the inability to generate what?
Normal respiratory pressures - they have weak cough, difficulty clearing secretions, aspiration
What medicines are patients with chronic extrinsic RLDs due to neuromuscular disorders sensitive to?
Respiratory depressants and paralytics
What lung capacity is an important indicator of the severity of RLD? What volume is considered severe?
Vital capacity, Less than 15cc/kg is considered severe (normal is 70cc/kg)
If the bulbar muscles are affected by a patient’s neuromuscular disease, what are they at high risk for?
Aspiration
What anesthetic consideration is key in managing your patient with a RLD?
Preoperative evaluation
What parts of a patient’s medical history should be targeted to assess severity of their RLD?
Exercise tolerance, nature of disease, recent infections, comorbidities, smoking hx
What is important in the physical exam of a patient with RLD to assess the severity?
Baseline pO2, breathing pattern, RR, auscultate lungs, cyanosis, body habitus
What ABG results are signs of respiratory failure/end stage disease?
Hypoxia, hypercapnia
What EKG manifestations help evaluate the severity of a patient with RLD
Right axis deviation, P pulmonate (waves higher than 2.5mm in lead 2), RVH, RBBB
What patient-related factors put them at high pulmonary risk?
Old age, ASA greater than 2, CHF, functional dependency, COPD, serum albumin less than 35g/L
What procedure-related factors put patients at high pulmonary risk?
Surgery greater than 3 hours, thoracic/abdominal/neuro surgery, head/neck surgery, aortic aneurysm repair, emergency surgery, general anesthesia
For preoperative risk reduction, encourage cessation of smoking for at least _ weeks
6
What are the benefits of general anesthesia in patients with a RLD?
Able to control oxygenation/ventilation, ability to suction airway, recruitment maneuvers
What can be expected after induction in patients with RLD?
Rapid desaturation due to their decreased FRC
What is the calculation for ideal body weight
Height in cm - 100 +/- 10%
What is the shortcut for calculating IBW for females
100 lbs + 5 lbs for every inch over 5 ft
What is the shortcut for calculating IBW for males
110 lbs + 5 lbs for every inch over 5 ft
What is the calculation for BMI
Weight in kg / height in meters squared
BMI over __ is defined as overweight
24
A BMI of 28-35 is defined as what?
Obese
People who are __% over their IBW are defined as obese
20%
Waist size greater than __ in males and __ in females is defined as obese
40, 25
People who are __ times their ideal body weight are defined as morbidly obese
2x
A BMI over __ is classified as morbid obesity
40
Give some examples of diseases linked to obesity
Diabetes, CHD, hypertension, stroke, arthritis, GERD, cancer
Obese individuals are at greater risk of developing what 3 cardiovascular disorders
Hypertension, stroke, CAD
What are the 2 forms of stroke
Ischemic and hemorrhagic
When does an ischemic stroke occur
When an artery to the brain is blocked
What body characteristics increase the risk for ischemic strokes in men and women
Overweight and obesity
The risk of ischemic strokes are doubled in those with a BMI over __
30
When do hemorrhagic strokes occur
When a blood vessel in the brain erupts
Are hemorrhagic strokes affected by body weight?
No
What is coronary artery disease?
A type of atherosclerosis that occurs when the arteries supplying blood to the heart become hardened and narrowed due to plaque buildup
What is the most common bariatric procedure in the U.S?
Gastric restriction with bypass
Obese individuals are at greater risk of developing what 2 gastrointestinal disorders?
Colon cancer, gall stones
What is the second leading cause of cancer-related deaths in the US?
Colorectal cancer
What is the primary hepatobiliary pathology associated with overweight?
Cholelithiasis - presence of gallstones
Obese individuals are at greater risk of developing what 3 metabolic disorders?
Diabetes Mellitus, dyslipidemia, liver disease
What 3 things make up the triad of metabolic syndromes?
Obesity, hypertension, type II diabetes
A weight gain of __-__ pounds increases the risk of developing Type 2 diabetes
11-18 pounds
Over __% of people with Type 2 DM are overweight or obese
80%
What is dyslipidemia
An abnormal concentration of lipids or lipoproteins in the blood
What is the term given to describe a collection of liver abnormalities that are associate with obesity?
Nonalcoholic fatty liver disease (NAFLD)
What is steatosis
A pathological finding that means “fatty liver”
How is cortisol production changed in obese people?
Increased cortisol production
How are progesterone, testosterone, and growth hormone levels affected in obese people?
All are decreased
What should you assess for in a cardiac evaluation of your obese patient?
Prior MI, hypertension, angina, PVD
What are some indications of left ventricular dysfunction?
Limited exercise tolerance, history of orthopnea, paroxysmal nocturnal dyspnea
Severely obese total body water is __%, compared to normal body water percentage of __%
40%, 60-65%
Estimated blood volume in obese patients is __-__ mL/kg, compared to __mL/kg for the non-obese
45-55 ml/kg; 70ml/kg
What is the recommended volume of Hetastarch (Hespan) to administer?
20mL/kg
What should you use to replaced blood loss in obese patients?
Crystalloid 3:1 ratio
What should you avoid during volume replacement of obese patients?
Rapid rehydration
What can you use during volume replacement in obese patients to support circulatory volume and oncotic pressure?
Albumin 5% or 25%
What physiologic changes can be seen in obese patients with OHS?
Hypersomnolence, arterial hypoxemia, polycythemia, hypercarbia, respiratory acidosis, pulmonary htn, RV failure
What positions accentuate restrictive lung disease symptoms in obese patients?
Supine and trendelenberg
What occurs if a patients FRC falls below closing capacity
Alveolar collapse, V/Q mismatch
What 3 statements make up the Desaturation Theory
- FRC is reduced by 1.5L by positioning and general anesthesia
- FRC is usually 2-2.5L
- Under general anesthesia, FRC is about 1 L
How fast will a patient with a BMI over 43 desaturate
Less than 130 seconds
How are lung volumes (TV, IRV, and ERV) affected by obesity
TV normal or decreased, IRV decreased, ERV greatly decreased
Even after an 8 hour fast, most morbidly obese patients have gastric volumes over __ mL and gastric pH below ___
25mL, 2.5
What is the best treatment to prevent aspiration during surgeries on morbidly obese patients?
H2 blockers the night before surgery
What inhalation agent is the most resistant to hepatic degradation?
Desflurane
Why is desflurane the preferred inhalation agent in obese patients?
Low solubility, rapid washout, absence of hepatic/renal toxicity, supports blood pressure
What drugs can be given preoperatively to obese patients to decrease risk of aspiration pneumonitis
Metoclopramide, H2 antagonist
What labs should be assessed preoperatively for obese patients?
Cardiopulmonary reserve, ABG, EKG, PFT
What are patient risk factors for difficult bag/mask ventilation
Age over 55, beard, snoring history, edentulous, BMI over 26
What are the 6 Ds of physical signs of a difficult airway?
- Disproportion (tongue size)
- Distortion (neck mass)
- Decreased thyromental distance
- Decreased inter incisor gap
- Decreased range of motion
- Dental overbite
What is a simple clinical sign to assess jaw function and addresses D3 and D6 of the 6 Ds?
The bite test - ask patient to touch upper lip with lower teeth, protrudes the mandible and assesses thyromental distance and overbite
What is the “HELP” position
Head elevated laryngoscopy position - helps improve view during a DL of an obese patient, increases the time to desat, and facilitates rescue ventilation techniques
What is the best position for obese patients to optimize pulmonary function
Reverse trendelenberg
What does pleuritic chest pain indicate in patients coming in for thoracic surgery
The disease has spread to the pleura
What are the symptoms of Horner’s syndrome
Ptosis, miosis, anhidrosis, conjuctiva, flushing
What causes Horner’s syndrome
Apical lung tumor or venous congestion
A ppo FEV1 result under what percentage is assc. with increased morbidity/mortality
40%
A pop FEV1 result under what percentage is assc. with post-op ventilatory support
30%
What position are VATS and thoracotomy procedures typically done under?
Decubitus
What component of the ventilator could you use to limit V/Q mismatch in an anesthetized patient undergoing thoracic surgery
Add PEEP
What are 3 absolute indications for one lung ventilation
Contamination (i.e. pneumonia), control distribution of ventilation (fistula), bronchoalveolar lavage
What are the relative indications for one lung ventilation
Thoracic aneurysm, pneumonectomy, upper lobe procedures, esophagectomy, transplant
Why can one lung ventilation lead to hypoxemia?
V/Q mismatch, shunt, decreased fio2, inadequate ventilation, anemia, impaired diffusion
Patients usually tolerate which sided surgery requiring one lung ventilation
Left side because the right lung is bigger
How does hypoxic pulmonary vasoconstriction help in one lung ventilation
Decreases blood flow to the bad lung, reduces shunt fraction and improves oxygenation
What are some factors that can inhibit HPV
Vasodilators, PEEP, Ca2+ channel blockers, hypocapnia, hypercarbia/hypoxemia, hypothermia
Why is it more challenging to place a right sided double lumen tube?
The right upper lobe take off is much shorter than the left, have a small margin of error
When would a right sided double lumen tube be indicated
Patients with tumor in mainstream, left sided single lung transplant, anastomosis
What size ETT do we use with bronchial blockers?
Usually 8.0 or 8.5
What tidal volumes should you deliver to the ventilated lung during one lung ventilation
6-8ml/kg
What should you keep your peak pressures under during one lung ventilation
25cmH2O
What is the most common vent mode for one lung ventilation
Pressure support
Why should you cation CPAP to non ventilated lung
It can impair surgical exposure
Why should you caution PEEP in the ventilated lung during OLV
Could distort surgical field, also caution in patients w/ COPD, emphysema - could cause bullae to rupture or autoPEEP
Which lung resection procedure has the most morbidity and incidence of arrhythmias
Pneumonectomy (whole lung)
What is post-pneumonectomy syndrome
Mediastinal shift which causes stretching and compression of the tracheobronchial tree and esophagus
What is the main symptom of post-pneumonectomy syndrome
Shortness of breath
In which lung is post-pneumonectomy syndrome most common
Left pneumonectomy
What is the treatment for post-pneumonectomy syndrome
Saline filled implants in vacant hemithorax
Which lung has the highest incidence for post-pneumonectomy pulmonary edema
Right
What are the main etiologies of tracheal disease
Prolonged intubation, extrinsic airway compression, mass/tumor
Tracheal resections may need what types of special ventilation
Jet ventilation (low volume, high pressure), cross table ventilation
Which anesthetic method is best for a tracheal resection
TIVA
What should you consider for emergency/extubation in a tracheal resection
Deep extubation, using dexmetetomidine
What is LVRS
Lung volume reduction surgery
How should you manage ventilation/oxygenation in patients having a LVRS
No peep, long expiratory time to avoid breath stacking and ruptured bullae
What side should a pulse ox be placed for mediastinoscopy
Right side to monitor for nominate artery compression
What diseases indicate a lung transplant
End stage lung disease - COPD, cystic fibrosis, a1 antitrypsin deficiency, pulmonary HTN, pulmonary fibrosis
When are epidurals for thoracic surgeries indicated
Thoracotomies, patients with chronic pain
When should a paravertebral block be considered in thoracic surgery
In patients with contraindications to neuraxial methods
