Restrictive Lung Disease Flashcards
What is the basic physiology with restrictive lung disease?
- Decreased lung volumes and compliance- multiple causes
- skeletal structure
- weakened muscles of respiration
- abdominal wall or contents can affect mobility of diaphragm and thoracic cage
- obesity, pregnancy
- creates a V/Q mismatch
Describe the flow volume loop seen in restrictive lung disease
- Same shape as normal, but much smaller
- This is not a disease of flow b/c flow is adequate, it is a disease of compliance and volume
What will pulmonary function tests show in a pt with restrictive lung disease?
- Reduction in:
- total lung capacity- used to classify severity of the restrictive dx
- mild: 65-80%
- moderate: 50-65%
- severe: <50%
- FRC
- Reserve volume
- vital capacity
- FEV1 (forced expiratory volume in 1 second)
- FVC (forced vital capacity)
- total volume exhaled
- total lung capacity- used to classify severity of the restrictive dx
-
NO change in FEV1: FVC ratio
- b/c it is not a disease of flow, it is a disease of compliance
Reduced lung compliance leads to _______ and _______.
decreased FRC and arterial hypoxemia due to V/Q mismatch.
AND
increased WOB and dyspnea
What does the breathing pattern look like for a pt with restrictive lung disease?
- Rapid and shallow, which increases dead space ventilation
What are the different classifications of restrictive lung disease?
- Acute intrinsic
- pulmonary edema
- ards
- Chronic intrinsic
- diseased lung parenchyma- sarcoidosis (inflammatory disease)
- Chronic Extrinsic
- chest wall, intraabdominal, and neuromuscular diseases
- Disorders of the pleura and mediastinum
What is Pulmonary edema?
Classification?
Causes?
Diagnosis?
- Leakage of IVF from the pulmonary vasculature into the lung interstitium and into the alveoli
- Acute intrinsic restrictive lung disease
- Causes:
- increased capillary hydrostatic pressure (cardiogenic pulm edema)
- increased capillary permeability (inflammatory process)
- Diagnosed:
- bilateral symmetrical opacity on CXR
- If cardiogenic, will see accompanying dyspnea, tachypnea, SNS activation
What is aspiration pneumonitis?
Classification?
Symptoms?
- Aspirate is rapidly distributed throughout lungs and gastric fluid destroys the surfactant-producing cells and injurs the endothelium of the capillaries
- Causes capillary permeability with atelectasis and edema formation
- Acute intrinsic classification
- Symptoms:
- arterial hypoxemia
- tachypnea
- bronchospasm
- pulmonary vascular constriction can develop into pulmonary HTN
- CXR changes 6-12 hrs after event.
- usually right lower lobe
How is Aspiration pneumonitis treated?
- deliver increased FiO2
- Give PEEP
- Beta2 agonists for bronchospasm
- prophylactic anitbiotics and steroid use not supported
What is Negative Pressure Pulmonary edema?
Classification?
Causes?
- Occurs minutes to 3 hours after acute upper airway obstruction in a spontaneously breathing patient due to high negative intrapleural pressures against a closed glottis/upper airway
- Acute Intrinsic
- Causes:
- post-extubation laryngospasm
- OSA
- hiccups
- epiglottitis
- Tumors
In negative pressure pulmonary edema:
What do the highly negative intrapleural pressures cause?
What does this result in?
- Decreased interstitial hydrostatic pressure
- increased venous return
- increased afterload on left ventricle
- increased SNS outflow- HTN, central displacement of blood volume
- *Results in acute pulmonary edema
- **the high negative pressures can only be caused by a pt spontaneously breathing
How does a pt with Negative pressure pulmonary edema present?
How long does it last?
Treatment?
- Presents with:
- tachypnea
- cough
- failure to maintain SaO2 > 95%
- Most commonly seen in muscular men- b/c they can generate strong neg pressures
- Duration: usually self limited, lasting 12-24 hours
- Treatment:
- supplemental O2
- maintenance of patent upper airway
- occasionally mechanical ventilation is required for a brief period
What is Sarcoidosis?
Classification?
Where is it often found?
- Systemic granulomatous disorder that changes the intrinsic properties of the lung due to pulmonary fibrosis and results in pulm HTN and cor pulmonale–> results in more fibrosis and loss of pulmonary vasculature
- Chronic Intrinsic
- Often found in the thoracic lymph nodes and lungs
What is a potential problem with a laryngeal sarcoid?
a Myocardial sarcoid?
- Laryngeal sarcoid
- can interfere with the passage of an adult sized tube
- Myocardial sarcoid
- rare conduction defects ( heart block, dysrhythmias, restrictive cardiomyopathy
How do patients with Sarcoidosis present?
What kind of procedure are they probably getting
How should you consider?
- Patients present with:
- dyspnea/cough
- rapid, shallow breathing
- sometimes asymptomatic but diagnosed by abnormal CXR
- Procedure: mediastinoscopy for diagnosis via lymph node tissue
- Patients are often treated with corticosteroids, consider need for stress dose
What are some causes of chronic extrinis restrictive lung disease?
What does this do to the lungs?
- Disorders of the thoracic cage that inhibit lung expansion
- skeletal deformities: scoliosis, kyphosis, ankylosing spondylitis
- Neuromuscular disorders
- Lungs are compressed and volumes are reduced; WOB increased
- May cause compression of pulmonary vasculature and lead to RV dysfunction
- recurrent pulmonary infection and cough are common
What is the one acute extrinisc restrictive lung disorder mentioned?
Flail chest, seen in traumas
How do neuromuscular disorders cause restrictive lung disease?
- they cause the inability to generate normal inspiratory and expiratory respiratory pressures
- Also have:
- impaired cough/clearance of secretions; often leading to frequent infection and COPD
- impaired swallow leading to aspiration
- PNA
- These pts are very sensitive to CNS depressants
What are the problems that come along with mediastinal tumors?
What should you do before the case?
- Progressive airway obstruction
- loss of lung volumes
- Compression of pulmonary artery myocardium or SVC
- obstruction of venous pressure–>JVD
- conjunctival edema, increased ICP
-
May occlude airway in supine positions and/or if given muscle relaxant
- may require awake fiberoptic intubation
- Requires CXR, CT scan, PFT, and clinical evaluation for tracheobronchial compression before case
How should you assess a pt with restrictive lung disease preoperatively?
What might indicate higher risk?
- Assessment:
- Exercise tolerance and baseline dyspnea
- PFTs, flow-volume loops
- ABG
- Factors that signal increased risk:
- decrease in VC < 15 ml/kg
- resting hypercarbia
How can you optimize a pt with restrictive lung disease before a procedure?
- Treat any pulmonary infection
- improve sputum clearance
- treat cardiac dysfunction
- attempt to improve respiratory muscle strength w/respiratory therapy techniques
- Incentrive spirometry
- smoking cessation
How should you ventilate a patient with restrictive lung disease while under anesthesia?
- Mechanical ventilation with ETT
- Pre-oxygenation is very important
- SaO2 will drop quickly d/t low FRC
- Lower TV (4-8 ml/kg) and higher RR (14-18 BPM)
- because positive pressure ventilation results in high airway pressures in order to expand stiff lungs
- attempt to keep end-inspiratory plateau pressure <30 cmH2O
- Consider risk for Barotrauma
What are some anesthetic considerations for a pt with restrictive lung disease?
pre-induction
regional
N2O
Maintenance
-
Pre-induction: titrate pre-meds carefully to avoid respiratory depression
- especially b/c they depend on high rate and low TV
- Regional: if block is above T10 level, pt will have loss of accessory respiratory muscles which may have a huge affect on their spontaneous ventilation
- N2O should be used with caution due to risk of barotrauma (pneumothorax). Just avoid in this pt population
- Maintenance: use shorter acting agents to prevent post-op resp. depression
How will pts with restrictive lung disease respond to volatile agents?
- They will have an accelerated uptake due to decreased FRC and increased RR
What criteria do pts with restrictive lung disease need to meet for extubation?
- Adequate PaO2 >60 mmHg
- PaCO2 < 50 mmHg
- RR < 30 bpm
- TV > 300 ml (at least 6 ml/kg)
- VC > 10-15 ml/kg
- Adequate level of consciousness and muscle strength
- sustained head lift >5 sec
- Full reversal of NMB
What affects do surgery and anesthesia have on VC and FRC in a normal healthy patient?
- VC decreases 40% after upper abdominal surgery and can take up to 14 days to return to normal
- FRC decreases 10-15% in supine, healthy, spontaneously breathing pts
- General anesthesia decreases FRC another 5-10%
- FRC requires 3-7 days to recover after upper abdominal procedures
- **wil be much worse in a pt with restrictive lung disease!
What are some post-anesthetic pulmonary problems a pt with restrictive lung disease might experience?
- Decreased lung volumes
- abdominal surgery may impinge movement of diaphragm
- abnormal respiratory pattern- shallow and rapid
- impaired cough (in neuromuscular disorders) leads to post operative respiratory failure
- always give O2 for transport
- treat pain adequately but avoid resp. depression
- More likely to require post-op mechanical ventilation- have low threshold
If emergency surgery is indicated for a pt with acute restrictive and critically ill patient, what can you do to optimize them?
- Diuretic therapy for fluid overload
- vasodilators and inotropes for cardiac failure
- consider drainage of pleural effusions/ascites pre-op
- may require ICU ventilator
- use aggressive hemodynamic monitoring
- art line, CVP, PA
What else can cause a restrictive picture?
obesity
pregnancy
liver disease with ascites
