Obstructive lung disease Flashcards
Preoperative pulmonary testing is indicated for which of the following patients?
A. A patient with a baseline NaHCO3 35 mEq/L
B. A patient undergoing a planned pneumonectomy
C. A patient with hypoxemia on room air (PaO2 < 60 mmHg)
D. A patient with suspected pulmonary hypertension
E. All these patients should undergo preoperative pulmonary testing.
E.
What is obstructive lung disease?
pulmonary conditions characterized by airflow limitation
can be inside the lumen, bronchial wall, or peri bronchial region- reversible vs. non-reversible
Orthostatic sleep apnea is a
mechanical obstruction of breathing that occurs during sleep when pharyngeal muscles relax
Risk factors for OSA include:
occurs in 24% of males & 9% of females
obesity is most significant precipitating factor
increasing incidence in pediatric cases
OSA is an independent risk factor for
increased morbidity
With OSA obstructed airways lead to
chronic hypoxemia and hypercarbia
results in inflammatory state, other pathologies such as atherosclerosis, HTN, stroke, insulin resistance and diabetes; Low FRC
Clinical features of OSA include
hallmark of OSA is habitual snoring, fragmented sleep, and daytime somnolence
Patients with OSA present with comorbidities related to
obesity, hypoxemia
systemic & pulmonary hypertension, ischemic heart disease, and CHF
Diagnosis of OSA can be done through
polysomnography- records the number of abnormal respiratory events/ Hr (the apnea plus hypo apnea index, AHI)
If a patient has OSA, there is no evidence that
delaying a case will improve outcomes
For AHI & OSA diagnosis,
> 5 associated with sleep-related symptoms
15 is diagnosis for moderate OSA
30 severe OSA
What does STOP BANG stand for?
Snore loudly daytime Tiredness Observed stop breathing High blood Pressure BMI> 35kg/m^2 Age> 50 years Neck circumference >40 cm Gender- male
FEV1 is the
volume of air forcefully exhaled in one second (80-120% of predicted value)
FVC is the
volume of air forcefully exhaled after a deep inhalation (3.7L females, 4.8 L in males
The normal FEV1 to FVC ratio is
75-80%
The most clinically useful test of lung function includes
spirometry
FEV 25-75% is
measurement of air flow at midpoint of a forced exhalation
The Maximum voluntary ventilation (MVV) is the
maximum amount of air that can be inhaled and exhaled in 1 minute
males 140-180 and females 80-120 L/min respectively
The diffusing capacity or DLCO is
the volume of carbon monoxide transferred across the alveoli into the blood per minute per unit of alveolar partial pressure
normal value is 17-25 mL/min/mmHg
a single breath of 0.3% CO and 10% helium is held for 20 seconds
The “common cold” results in
22 million doctor visits annually
-infectious (viral or bacterial) nasopharyngitis accounts for 95%
Diagnosis of acute upper respiratory infection is based on
signs & symptoms- non-productive cough, sneezing, and rhinorrhea
bacterial infections more serious and include- fever purulent nasal damage, productive cough and malaise, patient may present with tachypnea and wheezing
Pediatric patients with acute upper respiratory infection are at higher risk for
complications when actively sick, have history of reactive airway disease, ETT intubation, and airway surgery
The urgency of surgery should be determined to decide the case should be cancelled or not
If a case is cancelled due to acute upper respiratory infection it should not be rescheduled for
six weeks
The anesthetic management for acute upper respiratory infection includes
hydration, reducing secretions, limited airway manipulation, and LMA vs. ETT
Adverse respiratory events with acute upper respiratory infection include:
bronchospasm, laryngospasm, airway obstruction, postoperative croup, desaturation
Asthma is a
reversible airway obstruction characterized by: bronchial hyperreactivity, bronchoconstriction, and chronic inflammation of the lower airways
The development of asthma is due to
multifactorial- genetic or environmental
Describe the pathophysiology of asthma.
activation of the inflammatory pathway leads to infiltration of airway mucosa with:
-eosinophils, neutrophils, mast cells, T cells and B Cells
inflammatory mediators include: histamine, prostaglandin D, and leukotrienes
airway edema results and there is thickening of the basement membrane
simultaneous edema and repair
Signs and symptoms of asthma include
episodic disease with symptom-free periods with acute exacerbations- episodes may last minutes to hours but patiently completely recovers
phases of daily attacks with some degree of obstruction
Clinical manifestations of asthma include
wheezing, productive and nonproductive cough, dyspnea and chest discomfort leading to air hunger, eosinophilia
Status asthmaticus is an
asthma exacerbation that persists despite treatment
Diagnosis of asthma is dependent on
symptoms- wheezing, chest tightness, shortness of breath, airflow obstruction that is partially reversible with bronchodilators AND
pulmonary function testing
Patients with asthma have these changes on a pulmonary function test
FEV1 less than 35% of normal
downward “scooping” of expiratory limb of loop
Increase in FRC, but TLC remains within normal limits
DLCO is uncahnged
Arterial blood gases for patients with asthma are
normal in mild disease
hypocarbia and respiratory alkalosis are common- reflects neural reflex changes in lungs, not hypoxemia
For patients with severe asthma obstruction, the arterial blood gases are associated with
PaO2 less than 60 mmHg
rises in PaCO2 noted when FEV1 is less than 25%- fatigue in accessory muscles contributes to hypercarbia
Discuss the chest radiograph appearance for patients with asthma.
may be normal
-with severe asthma they may have hyperinflation or hilar congestion due to mucus plugging and pulmonary hypertension
The EKG of patients with asthma may show
right ventricular strain associated with increased pulmonary pressures
T wave inversion in right precordial leads (V1-4) and inferior leads (II, III, and aVF)
Status asthmaticus is a
life threatening emergency in which bronchospasm does not respond to treatment
Treatment of status asthmaticus includes:
IV corticosteroids, supplemental oxygen, IV magnesium sulfate to cause relaxation, oral leukotriene inhibitor, and administration of B2 agonists- metered dose inhaler, nebulizer, injection (IV or subcutaneous)
For patients with status asthmaticus who are resistant to treatment, think
airway edema and secretion
The treatment of patients with asthma is focused on
treating inflammation and bronchospasm
Drugs that are used to treat asthma include:
corticosteroids- beclomethasone long-acting bronchodilators- salmeterol; combination- Symbicort and Advair Leukotriene modifiers- singular Anti-IgE monoclonal antibody- omalizumab Methylxathines- theophylline mast cell stabilizer- cromolyn
For patients with asthma who have PFT’s performed,
it an be useful in determining treatment response
FEV1 is greater than 50% of normal= symptom free
For patients with asthma, it is important to investigate this in the preoperative period.
preoperative history- assessment of disease severity & treatment effectiveness
includes:
severity and characteristics of asthma- used of accessory muscles, active wheezing?
previous ICU admission or intubation required?- two or more in the past year?
eosinophil counts (inflammatory process)
PFT results- FVC <70% or Fev1/FVC <65% increases perioperative risk
presence of coexisting diseases
Should also assess for additional preoperative therapy