Restrictive Lung Disease '24 Flashcards
What do restrictive lung diseases affect?
Lung expansion and compliance
What is the hallmark of restrictive lung disease?
Inability to increase lung volume with alveolar pressure
What are some causes of restrictive lung disease?
Connective tissue diseases, environmental factors, pulmonary fibrosis, etc.
What do restrictive lung diseases lead to?
Reduced surface area for gas diffusion and hypoxia
Why do patients with RLD become symptomatic?
Due to hypoxia, inability to clear secretions, and hypoventilation
What is affected in restrictive lung diseases?
FEV1, FVC, TLC
What happens to FEV1:FVC ratio in restrictive lung diseases?
Normal or increased
What is reduced in restrictive lung diseases?
DLCO
What is the principal feature of Restrictive Lung Disease?
Decrease in TLC
How is Restrictive Lung Disease classified based on TLC?
Mild, moderate, severe
What TLC range is considered for mild disease in RLD?
65-80% predicted
What TLC range is considered for moderate disease in RLD?
50-65% predicted
What TLC range is considered for severe disease in RLD?
<50% predicted
What causes pulmonary edema?
Intravascular fluid leakage
What can acute pulmonary edema be caused by?
Increased capillary pressure or permeability
What is ‘capillary stress failure’?
Result of increased capillary pressure or permeability
How does pulmonary edema appear on CXR?
Bilateral, symmetric perihilar opacities
What pattern is more commonly seen with increased capillary pressure?
Butterfly fluid pattern
What characterizes pulmonary edema due to increased capillary permeability?
High concentration of protein and secretory products
What lung condition is associated with increased-permeability pulmonary edema?
ARDS
Cardiogenic pulmonary edema: What is it associated with?
Acute decompensated heart failure
Cardiogenic pulmonary edema: What are the common characteristics?
Marked dyspnea, tachypnea, elevated cardiac pressures, SNS activation
Cardiogenic pulmonary edema: When should it be suspected?
If a patient has decreased systolic or diastolic cardiac function
Cardiogenic pulmonary edema: What conditions increase the risk?
Conditions that increase preload (acute aortic regurgitation, acute mitral regurgitation), afterload (LV outflow tract obstruction, mitral stenosis) or SVR (reno-vascular HTN)
What is another name for Negative pressure pulmonary edema?
Post-obstructive pulmonary edema
What causes Negative pressure pulmonary edema?
Laryngospasm, epiglottitis, tumors, obesity, hiccups, OSA
What is necessary to create negative pressure in Negative pressure pulmonary edema?
Spontaneous ventilation
What are common signs of Negative pressure pulmonary edema that may be confused with aspiration or pulmonary embolism?
Tachypnea, cough, failure to maintain Sp02 >95%
How does negative intrapleural pressure contribute to the pathogenesis of Negative pressure pulmonary edema?
Decreases interstitial hydrostatic pressure, increases venous return
What is the treatment for Negative Pressure Pulmonary Edema?
Supplemental O2 and patent airway
When may mechanical ventilation be needed in Negative Pressure Pulmonary Edema?
Occasionally for a brief period
How long does it take for radiographic evidence of NPPE to resolve?
12-24 hours
When does Neurogenic Pulmonary Edema occur?
Minutes-hours after CNS injury
What causes Neurogenic Pulmonary Edema?
Massive SNS impulses from injured CNS
What leads to fluid transfer into the interstitium and alveoli in Neurogenic Pulmonary Edema?
Increased pulmonary capillary pressure
What can also injure blood vessels in the lungs in Neurogenic Pulmonary Edema?
Pulmonary HTN and hypervolemia
What is REPE?
Rapid expansion of a collapsed lung
What factors contribute to the risk of REPE?
Amount of air/liquid, duration of collapse, speed of re-expansion
Why does the high protein content of pulmonary edema fluid matter?
Enhanced capillary membrane permeability
How is REPE treated?
Supportive care
What drugs can cause acute noncardiogenic pulmonary edema?
Opioids and cocaine
What is the high protein concentration in pulmonary edema fluid suggestive of?
High-permeability pulmonary edema
What effects does cocaine have on the pulmonary system?
Pulmonary vasoconstriction
Is naloxone effective in speeding up the resolution of opioid-induced pulmonary edema?
No evidence
What is another condition to consider in the differential diagnosis of drug-induced pulmonary edema?
Diffuse alveolar hemorrhage (DAH)
What is likely if pulmonary edema on chest x-ray does not respond to diuretics?
DAH
What is the treatment approach for drug-induced pulmonary edema?
Supportive, may include intubation and mechanical ventilation
What is high-altitude pulmonary edema (HAPE)?
Fluid accumulation in the lungs at high altitudes
At what heights does HAPE typically occur?
2500-5000m
What may influence the development of HAPE?
Rate of ascent to altitude
When does the onset of HAPE usually occur at high altitudes?
Within 48-72 hours
How is hypoxic pulmonary vasoconstriction related to HAPE?
Increases pulmonary vascular pressure
What is a treatment for HAPE?
02 administration and quick descent
How can oxygenation be improved in HAPE?
Inhalation of nitric oxide
When should elective surgery be delayed in patients with pulmonary edema?
Delay in such cases
What may be needed for large pleural effusions?
Drainage may be necessary
What may be required for persistent hypoxemia?
Mechanical ventilation and PEEP
What is recommended for ventilation in patients to keep end-inspiratory plateau pressure <30 cmH2O?
Low TV & RR 14-18
What is suggested for optimizing lung compliance?
Careful PEEP titration with inspiratory pause
How do patients with restrictive lung disease typically breathe?
Rapid, shallow breathing
Should tachypnea alone be used as a criterion for delaying extubation?
No, consider gas exchange and other factors
What are some symptoms of chemical pneumonitis?
Abrupt onset dyspnea, tachycardia, decreased SP02
How can aspiration of gastric fluid lead to lung injury?
Destroys surfactant-producing cells and pulmonary capillary endothelium
What is a common recommendation to decrease aspiration risk during intubation and extubation?
Keep the head of the bed elevated
What might be seen on CXR in cases of aspiration pneumonitis?
May not demonstrate evidence for 6-12 hrs
Where is evidence of aspiration most likely to be found in the lungs if a patient aspirated in the supine position?
Superior segment of the right lower lobe
What should be done if aspiration is noted in a patient?
Suction oropharynx, turn to side
Can Trendelenburg position prevent aspiration of gastric contents?
No, after contents in pharynx
How long should patients be monitored after an aspiration episode?
24-48 hrs
Why is measurement of gastric fluid pH useful?
Reflects pH of aspirated fluid
How is aspiration pneumonitis best treated?
Supplemental O2 & PEEP
When may antibiotics be considered in aspiration pneumonitis?
Symptomatic after 48 hrs, positive culture
What is EVALI?
Form of ALI associated with vaping
What are some additives associated with EVALI?
THC, vitamin E acetate, nicotine
What are common symptoms of EVALI?
Dyspnea, cough, N/V/D
What are radiologic findings seen in EVALI?
Similar to diffuse alveolar damage in ARDS
What are the mainstays of therapy for EVALI?
Antibiotics, systemic steroids, supportive care
What is a common finding in survivors of severe acute SARS-CoV-2?
Drop in diffusion capacity
What are some long-term pulmonary complications faced by severe COVID-19 survivors?
Decreased exercise capacity, hypoxia, opacities on CT
What puts patients at the highest risk for long-term pulmonary complications?
Mechanical ventilation
What is one criteria for the presence of Acute Respiratory Failure?
Pa02 <60 mmHg despite 02 supplementation and no intracardiac shunt
How can the relationship of PaC02 to arterial pH help distinguish between acute and chronic respiratory failure?
In ARF, abrupt increases in PaC02 and decreases in pH are typical
What are the three treatment goals of Acute Respiratory Failure?
Patent airway, hypoxemia correction, removal of excess CO2
How can oxygen be provided?
NC, venturi mask, nonrebreather, T-piece
At what point is continuous positive airway pressure (CPAP) initiated?
When PaO2 <60 mmHg
What is the goal of maintaining oxygenation levels?
PaO2 >60 mmHg or SpO2 >90%
What is the variable that changes in volume-cycled ventilation (VCV)?
Inflation pressure
What happens when inflation pressure exceeds a set value in VCV?
Pressure relief valve prevents further gas flow
What does it indicate if there’s a significant increase in peak airway pressure in VCV?
Worsening pulmonary edema, pneumothorax, kinked ETT, or a mucous plug
Can tidal volume be maintained with small changes in peak airway pressure in VCV?
Yes
What is a disadvantage of VCV?
Inability to compensate for leaks
What are the primary modes of VCV?
Assisted/controlled ventilation (A/C) and synchronized intermittent mandatory ventilation (SIMV)
What does A/C ventilation ensure?
Set RR and delivered tidal volume
What does SIMV allow while providing a predefined minute ventilation?
Spontaneous ventilation
What are the advantages of SIMV over A/C ventilation?
Continued use of respiratory muscles, lower pressures, prevention of alkalosis, improved coordination
How does pressure-cycled ventilation work?
Provides flow until preset airway pressure is reached
What is the most important predisposing factor for developing nosocomial pneumonia in patients with acute respiratory failure on mechanical ventilation?
Intubation
What is the primary cause of ventilator-associated pneumonia?
Micro-aspiration of contaminated secretions around the ETT cuff
What condition is strongly related to the presence of a nasotracheal tube?
Nosocomial sinusitis
What are the treatments for nosocomial sinusitis?
Antibiotics, replacing nasal tubes with oral tubes, decongestants, head elevation
What may barotrauma present as in mechanically ventilated patients?
Subcutaneous emphysema, pneumomediastinum, pneumoperitoneum, pneumopericardium, arterial gas embolism, tension pneumothorax
What usually causes the various manifestations of extra-alveolar air seen in barotrauma?
Dissection or passage of air from overdistended and ruptured alveoli
How does infection increase the risk of barotrauma in mechanically ventilated patients?
By weakening pulmonary tissue
Common cause of hypoxemia during mechanical ventilation
Atelectasis
Initial checks for acute hypo-oxygenation in mechanically ventilated patients
ETT migration, kinks, mucous plugs
Is hypoxemia due to atelectasis responsive to an increase in FiO2?
No
Sudden hypoxemia in mechanically ventilated patients can also be caused by
Tension pneumothorax and pulmonary embolism
Possible accompaniment of tension pneumothorax and PE in ventilated patients
Hypotension
Potential method to remove mucous plugs in mechanically ventilated patients
Bronchoscopy
How can atelectasis be identified on bedside lung ultrasound?
Presence of static air bronchograms
What reflects the adequacy of oxygen exchange across alveolar capillary membranes?
PaO2
How is the efficacy of oxygen exchange measured?
Difference between calculated alveolar PaO2 and measured PaO2
Why is calculating the difference between Alveolar PaO2 and measured PaO2 useful?
For evaluating gas exchange and distinguishing causes of arterial hypoxemia
When does significant desaturation of arterial blood occur in mechanical ventilation?
PaO2 <60mmHg
What are the 3 main causes of arterial hypoxemia in mechanical ventilation?
V/Q mismatch, right-to-left shunting, hypoventilation
Will increasing inspired O2 concentration likely improve PaO2 in cases of significant right-to-left pulmonary shunting?
No
What compensatory responses are seen in arterial hypoxemia when PaO2 is <60 mmHg?
Stimulated responses
What responses are seen in chronic hypoxemia when PaO2 is <50?
Carotid body-induced increase, hypoxic vasoconstriction, increased SNS activity
What does chronic hypoxemia lead to an increase in?
RBC mass
What does the PaCO2 reflect?
Adequacy of alveolar ventilation relative to CO2 production
What does the VD:VT ratio reflect?
Efficacy of CO2 transfer across alveolar capillary membranes
What is described as wasted or dead space in the lungs?
Ventilation to alveoli with adequate ventilation but inadequate or no pulmonary blood flow
Normal value of VD:VT ratio?
<0.3
What could cause an increased VD:VT ratio?
ARF, decreased COP, pulmonary embolism
What is hypercarbia defined as?
PaC02 >45mmHg
What is permissive hypercapnia?
Allowing PaC02 to increase to ≥55 to avoid intubation
What are the symptoms of hypercarbia related to?
Level and rate of C02 increase
What happens with acute increases in PaC02?
Increased CBF and ICP
What occurs with extreme increases in PaC02 to >80mmHg?
CNS depression
What does the difference between Pv02 and Ca02 - Cv02 reflect?
Adequacy of COP relative to tissue oxygen extraction
When does Pv02 <30 mmHg or Ca02 - Cv02 >6 mL/dL indicate the need to increase COP?
To facilitate oxygenation
What does a pulmonary artery catheter allow for?
Sampling mixed venous blood and measuring Pv02
What is intrapulmonary shunt?
Perfusion of nonventilated alveoli
How does right-to-left pulmonary shunting affect PaO2?
Decreases PaO2
Why do we calculate the shunt fraction?
Assessment of V/Q matching and response to interventions
What percentage does a physiologic shunt typically account for in COP?
2-5%
How is the passage of pulmonary arterial blood to the left side of circulation through the veins reflected?
Reflects right-to-left pulmonary shunt
What does determination of shunt fraction in pts breathing <100% O2 reflect?
Contribution of V/Q mismatching and intrapulmonary shunting
How does calculating the shunt fraction with 100% O2 breathing affect V/Q mismatching?
Eliminates contribution of V/Q mismatching
What are some essential considerations when determining if a patient can be safely weaned from ventilation?
Alert, cooperative, tolerate SV trial
What guidelines have been proposed for discontinuing mechanical ventilation?
VC >15 mL/kg, A-a gradient <350, PaO2 >60 mmHg on <50% FiO2, NIP >-20 cmH2O, normal pH, RR <20, VD:VT <0.6
What does breathing at rapid rates with low tidal volumes usually signify during vent weaning?
Inability to tolerate extubation
What are the 3 options considered when a patient is ready for a trial of vent withdrawal?
SIMV, Intermittent trials, Pressure support ventilation
What may deterioration in oxygenation after vent withdrawal indicate?
Progressive alveolar collapse
What can be used to respond to progressive alveolar collapse after vent withdrawal?
CPAP or NIPPV
What may interfere with successful extubation?
Workload on respiratory muscles, hyperinflation, secretions, bronchospasm, increased lung water, increased C02 production
What is the role of Noninvasive ventilation in vent weaning?
A bridge involving early extubation with immediate application
What are potential benefits of using NIV in vent weaning?
Decrease incidence of nosocomial pneumonia, shorten ICU stay, reduce mortality
What are the potential drawbacks of using NIV in vent weaning?
Impaired ability to clear airway secretions, inadequate minute ventilation
When should extubation be considered during vent weaning?
After tolerating 30min of SV with CPAP of 5 cm H2O without deterioration
What are the criteria for PaO2 and FiO2 during vent weaning?
PaO2 >60 mmHg, FiO2 <50%
What are the criteria for PaCO2 and pH during vent weaning?
PaCO2 <50mmHg, pH >7.30
What are some additional criteria for vent weaning before extubation?
PEEP <5cmH2O, RR <20, VC >15mL/kg
What considerations should be made regarding the patient before extubation?
Alert, active laryngeal reflexes, effective cough
Why is oxygen supplementation often needed after extubation?
Due to V/Q mismatching
How is oxygen weaning achieved?
Gradually decreasing inspired O2, monitoring PaO2 or SpO2
What is the cause of ARDS?
Inflammatory injury to the lung
What is a major risk factor for ARDS?
Sepsis
What are the hallmarks of ARDS?
Rapid-onset respiratory failure, arterial hypoxemia, CXR like cardiogenic edema
How do proinflammatory cytokines contribute to ARDS?
Increase alveolar capillary membrane permeability
What are some complications of ARDS?
Fibrosing alveolitis with persistent hypoxemia
What is included in the supportive care for ARDS?
Ventilation, antibiotics, stress ulcer prophylaxis, DVT prophylaxis, early enteral feeding
What are proposed therapies for life-threatening refractory hypoxemia in ARDS management?
Prone positioning and ECMO
How does prone positioning help in ARDS management?
Exploits gravity to recruit lung units
When can ECMO be considered in ARDS management?
Severe hypoxemic and/or hypercapnic respiratory failure
What is the aim of using ECMO in ARDS management?
Rest the lungs until severe hypoxemia and respiratory acidosis resolve
What are some additional supportive therapies in ARDS management?
Optimal fluid mgmt, NMB, inhaled nitric oxide, etc.
What is ILD?
Group of diseases with similar presentation and CXR findings causing restrictive physiology
What are some examples of ILDs?
Sarcoidosis, Hypersensitivity Pneumonia, Pulmonary Langerhans Cell Histiocytosis, Pulmonary Alveolar Proteinosis, Lymphangioleiomyomatosis
How do patients with ILD usually present?
With dyspnea and nonproductive cough
What complications can develop in ILD?
Pulmonary hypertension and cor pulmonale due to progressive pulmonary fibrosis
What is common in some ILDs like asbestosis and idiopathic pulmonary fibrosis?
Digit clubbing
What is a marker that has been studied in sarcoidosis?
serum amyloid A
What test is used to detect sarcoidosis and is similar to a tuberculin test?
Kveim test
What procedures may be necessary to provide tissue or bronchoalveolar lavage for diagnosing sarcoidosis?
mediastinoscopy, endobronchial/transbronchial ultrasound, bronchoscopy
What is the treatment for suppressing symptoms of sarcoidosis and treating hypercalcemia?
Corticosteroids
What can advanced pulmonary fibrosis lead to?
pulmonary hypertension
What is Hypersensitivity Pneumonitis characterized by?
Interstitial granulomatous in the lungs after inhalation of specific dust
What are the possible presentations of Hypersensitivity Pneumonitis?
Acute, subacute, chronic
What symptoms may patients experience with Hypersensitivity Pneumonitis?
Dyspnea & cough 4-6 hrs post exposure, leukocytosis, eosinophilia, hypoxemia
What might a CT scan show in a patient with Hypersensitivity Pneumonitis?
Ground-glass opacities in mid to upper lung zones
What procedures might patients with Hypersensitivity Pneumonitis present for?
Bronchoscopy, biopsy, cryobiopsy
What can repeated episodes of Hypersensitivity Pneumonitis lead to?
Pulmonary fibrosis
How is Hypersensitivity Pneumonitis treated?
Antigen avoidance, glucocorticoids, lung transplant
What is another name for Pulmonary Langerhans Cell Histiocytosis?
Eosinophilic granuloma
Where does the inflammation typically occur in Pulmonary Langerhans Cell Histiocytosis?
Around smaller bronchioles
What imaging technique can be diagnostic for Pulmonary Langerhans Cell Histiocytosis?
CT
What cells are found in inflammatory lesions around the bronchioles in Pulmonary Langerhans Cell Histiocytosis?
Langerhans cells, eosinophils, lymphocytes, neutrophils
What is a strong associated factor with Pulmonary Langerhans Cell Histiocytosis?
Smoking tobacco
What is the treatment for Pulmonary Langerhans Cell Histiocytosis?
Smoking cessation, glucocorticoids, symptomatic support
What is Pulmonary Alveolar Proteinosis (PAP)?
Lipid-rich proteinaceous materials in alveoli
What are common symptoms of PAP?
Dyspnea and hypoxemia
How is severe PAP treated?
Whole-lung lavage under GA
What can CXR show in PAP?
Batwing distribution of alveolar opacities
What may be required for airway management during lung lavage?
DLT for each lung separately
What is Lymphangioleiomyomatosis?
Rare multisystem disease
Who does Lymphangioleiomyomatosis mostly affect?
Women of reproductive age
What do PFTs show in Lymphangioleiomyomatosis?
Restrictive and obstructive disease with decreased diffusing capacity
What symptoms are associated with Lymphangioleiomyomatosis?
Dyspnea, hemoptysis, recurrent pneumothorax, pleural effusions
What treatment is indicated in symptomatic patients with progressive Lymphangioleiomyomatosis?
Sirolimus (immunosuppressive)
What are some physiologic changes in the lungs associated with aging?
Decreased chest wall compliance, decreased elastic recoil
How does aging affect residual volume and vital capacity?
Increased residual volume, decreased vital capacity
What happens to the functional residual capacity (FRC) in geriatric patients?
Increased FRC
What effect does aging have on the chest wall and diaphragm efficiency?
Kyphosis increases, chest AP diameter increases, diaphragm efficiency decreases
How does lung function decline in aging patients with regards to FEV1 and FVC?
Rapid decline in FEV1 and FVC
What happens to lung function decline in patients with increased airway reactivity and aging?
Even more rapid decline
What are the causes of chronic extrinsic restrictive lung disease?
Disorders of the thoracic cage
Which deformities can interfere with lung expansion in chronic extrinsic restrictive lung disease?
Deformities of sternum, ribs, vertebrae
How does chronic extrinsic restrictive lung disease affect the work of breathing?
Increased airway resistance
What can thoracic deformities lead to in chronic extrinsic restrictive lung disease?
Right ventricular dysfunction
Why do patients with chronic extrinsic restrictive lung disease have a poor ability to cough?
Increased airway resistance
What are the 2 types of costovertebral skeletal deformities seen in chronic extrinsic restrictive lung disease?
Scoliosis and kyphosis
What is the combination of scoliosis and kyphosis called?
Kyphoscoliosis
What can kyphoscoliosis lead to in terms of lung function?
Severe restrictive impaired lung function
What are the main causes of kyphoscoliosis?
Idiopathic, neuromuscular disorders, congenital vertebral malformations
When does kyphoscoliosis commonly begin and progress?
Late childhood/early adolescence, periods of rapid skeletal growth
How does kyphoscoliosis related to a neuromuscular disorder differ in respiratory compromise compared to idiopathic kyphoscoliosis?
More respiratory compromise
What are the effects of kyphoscoliosis on respiratory function?
Decreased ventilatory capacity & increased work of breathing
What correlates with the severity of respiratory compromise in kyphoscoliosis?
Degree of spinal curvature
What is pleural effusion?
Fluid in pleural space
How is pleural effusion diagnosed?
CXR, CT, or bedside US
What is pneumothorax?
Gas in the pleural space
What causes a pneumothorax?
Disruption of the parietal or visceral pleura
What demographic is most affected by idiopathic spontaneous pneumothorax?
Tall, thin men age 20-40
What causes secondary pneumothorax?
COPD, pulmonary malignancies, cystic fibrosis, lung abscesses
What is tension pneumothorax?
Gas enters pleural space, can’t escape
What are the symptoms of tension pneumothorax?
Respiratory distress, tachypnea, SOB, hypoxia, chest pain
How can tension pneumothorax be identified in physical examination?
Deviation of trachea, decreased/absent breath sounds
What can be observed in a ventilated patient with tension pneumothorax?
Increased airway pressures, decreased TV
What is the immediate life-saving treatment for tension pneumothorax?
Evacuation with needle or catheter
What may follow hemothorax, empyema, or surgical pleurodesis?
Pleural fibrosis
When is surgical decortication considered for restrictive lung disease?
When very symptomatic
What can cause acute mediastinitis?
Bacterial contamination after esophageal perforation
How is acute mediastinitis treated?
Broad-spectrum abx & surgical drainage
What are examples of anterior mediastinal masses?
Thymomas, germ cell tumors, lymphomas
What are examples of middle mediastinal masses?
Tracheal masses, bronchogenic cysts
What are examples of posterior mediastinal masses?
Neurogenic tumors, meningoceles
What are some treatment options for a mediastinal mass?
Surgery, radiation, chemotherapy, surveillance
What is involved in the preoperative evaluation of a mediastinal mass?
Flow-volume loop measurement, chest imaging, clinical evaluation for airway compression
How can the size of a mediastinal mass and tracheal compression be determined?
CT scan
What can be useful for evaluating the degree of airway obstruction in mediastinal masses?
Flexible fiberoptic bronchoscopy under topical anesthesia
Is the severity of preoperative pulmonary symptoms predictive of intraoperative respiratory compromise?
No
What should be considered for malignant mediastinal masses to decrease their size preoperatively?
Preoperative radiation
What technique is best for symptomatic patients requiring a diagnostic tissue biopsy?
LA technique
What is Jeune syndrome?
Autosomal recessive disorder with skeletal dysplasia and cysts in various organs
How does fibrodysplasia ossificans develop?
Genetic variation in BMP type 1
What is a symptom of Poland syndrome?
Absent or partial pectoral muscles
What is a potential complication of Poland syndrome?
Paradoxic respiratory motion
What are extrathoracic causes of restrictive lung disease?
Neuromuscular disorders
How do neuromuscular disorders affect CNS input to skeletal respiratory muscles?
Cause interference
What do abnormalities of spinal cord, nerves, NMJ, or muscles result in?
Restrictive pulmonary defects
In neuromuscular disorders, what is the impact on effective cough compared to mechanical thoracic cage disorders?
Preserved in mechanical; prevented in neuromuscular
What are patients with severe neuromuscular disorders dependent on to maintain adequate ventilation?
State of wakefulness
What may develop during sleep in patients with severe neuromuscular disorders?
Hypoxemia and hypercapnia
In quadriplegic patients with injury below T4, how is breathing maintained?
Diaphragm
Higher levels of spinal cord injury can result in what?
Diaphragmatic paralysis
Why is coughing almost totally absent in quadriplegic patients with injury below T4?
Diaphragm active only during inspiration
What motion of the upper thorax occurs during inspiration in quadriplegic patients with diaphragmatic breathing?
Paradoxic inward motion
What causes mild degrees of bronchial constriction in quadriplegic patients?
Parasympathetic tone unopposed by sympathetic activity
How can the abnormal bronchial constriction in quadriplegic patients be reversed?
Anticholinergic bronchodilating drugs
How does obesity affect lung function?
decreases FEV1, FVC, FRC, ERV
What BMI value is associated with a decrease in residual volume and TLC?
BMI > 40 kg/m2
What happens to FRC in extreme clinical obesity?
may exceed closing volume and approach residual volume
What lung function ratio is usually preserved in obesity?
FEV1:FVC
What is a good indicator of impaired lung function in obesity?
increased waist-to-hip ratio and/or abdominal girth
How does obesity hinder lung function?
adipose tissue buildup hinders diaphragmatic movement and causes closure of lung units
What can adipose cells release that play a role in systemic inflammation triggered by obesity-related hypoxemia?
Adipocytokines
How can arterial hypoxemia lead to respiratory compromise in obese individuals?
Due to ventilation/perfusion abnormalities
How does pregnancy affect lung physiology?
Increased subcostal angle, chest wall circumference, and diaphragm movement
What causes stretching of lower rib cage ligaments in pregnancy?
Increased levels of relaxin
When do the changes in chest wall configuration peak during pregnancy?
37th week
How much does the enlarging uterus push the diaphragm up by?
About 4 cm
Which drugs should be avoided in anesthetic management due to prolonged respiratory depressant effects?
Drugs with prolonged respiratory depressant effects
What should be maintained to avoid pneumothorax and the need to discontinue nitrous oxide?
Vigilance
What facilitates optimal oxygenation during surgery?
Intraoperative mechanical ventilation
Why may increased inspiratory pressures be necessary during anesthesia for patients with poorly compliant lungs?
Lungs are poorly compliant
When is postoperative mechanical ventilation often needed for patients?
Impaired pulmonary function
What contributes to the risk of perioperative pulmonary complications?
Restrictive lung disease
What has generally replaced rigid bronchoscopy for visualizing the airways and obtaining samples?
Fiberoptic bronchoscopy
What is a major contraindication to pleural biopsy?
Coagulopathy
What percentage of patients may experience pneumothorax after transbronchial lung biopsy?
5-10%
How is mediastinoscopy typically performed?
Under GA through a small transverse incision
What are the risks associated with mediastinoscopy?
PTX, mediastinal hemorrhage, venous air embolism, RLN injury
What can the mediastinoscope exert pressure on, potentially causing loss of pulses in the right arm?
Right innominate artery
