Download Anesthesia for Patients with Respiratory Disease

Anesthesia for Patients with Respiratory Disease
Patients with pre-operative pulmonary impairment are at increased risk for greater
intra-operative alterations in pulmonary function and more post-op pulmonary
complications.
Risk factors for post-op pulmonary complications
 Pre-existing pulmonary disease, especially history of dyspnea

Thoracic and upper abdominal surgery
o Diaphragm dysfunction
o FRC  60% after upper abdominal surgery, lasts 7 days
o Rapid shallow breathing with ineffective cough
o Impaired muco-ciliary clearance
o All leads to atelectasis,  lung volume,  shunt, hypoxemia

Smoking history

Obesity -  FRC,  work of breathing

Age -  incidence of pulmonary disease,  closing capacity
Obstructive pulmonary disease
Asthma, emphysema, chronic bronchitis, cystic fibrosis, bronchiectasis, bronchiolitis

Primary problem is resistance to airflow.
o Air trapping and prolonged expiratory times due to elevated
resistance to airflow
o Noisy breathing (wheezing, ronchi) due to turbulent air flow
o  Work of Breathing
o Impairment of respiratory gas exchange
o FEF 25-75 <70%; later FEV1 and FEV1/FVC <70%

Asthma
o Main problem is airway inflammation and hyper-reactivity
o Airway obstruction results from bronchial smooth muscle
constriction, airway edema, and  secretions
o Symptoms: wheezing, dyspnea, coughing
o Signs: delayed rise in CO2 during expiration on capnograph, indicating
airflow obstruction,  peak inspiratory pressures and incomplete
exhalation when obstruction is severe.
o Anesthetic considerations with asthma:
 Review the recent course of the disease with the patient. Have
they ever been hospitalized for asthma? Are they using
bronchodilators regularly? What bronchodilators? Do they
smoke? Have they had a recent URI?

Optimally, no wheezing, no cough, no dyspnea

Continue bronchodilators pre-operatively

Consider regional anesthesia or general anesthesia via LMA
because the biggest risk is instrumentation of the airway

Avoid histamine-releasing drugs: atracurium, morphine,
meperidine

Deepen anesthesia prior to intubation or surgical stimulation
with volatile anesthetic or lidocaine 1-2 mg/kg IV or sprayed in
trachea

Maintenance with volatile anesthetic for bronchodilating effect

Use airway humidification devices

Use smaller tidal volume with prolonged expiratory times. May
need to accept higher PCO2.

Treat intra-op bronchospasm by deepening anesthesia, giving
a -agonist (e.g. albuterol) by mist in the inspiratory limb of
the breathing circuit

Extubate deep if practical. Can precede extubation with more
lidocaine.

COPD
Patients are usually asymptomatic early, with  MMEF
o Chronic bronchitis
 Chronic productive cough

Airflow obstruction from secretions and airway inflammation

RVH, intra-pulmonary shunting, and hypoxemia are common

In advanced stages, chronic hypoxemia, pulmonary
hypertension, RV failure (“blue bloater”)

CO2 retention, blunting of respiratory drive from CO2

Respiration may be depressed by supplemental oxygen
o Emphysema
 Irreversible enlargement of distal airways and destruction of
alveolar septa causing increased dead space

Elastic recoil that normally supports small airways by radial
traction is lost, causing premature airway collapse during
exhalation

Patients often purse their lips on expiration (self-PEEP) to
delay closure of small airways (“pink puffer”)
o Anesthesia considerations with COPD
 Stop smoking 6 – 8 weeks if possible. Even stopping for 24
hours will  CO levels, improve oxygen carrying capacity, and
improve muco-ciliary clearance

Review PFTs, chest Xray, ABGs

Consider bronchodilators pre-op if they improved PFTs

High FiO2 – may abolish hypoxic respiratory drive

May need post-op ventilatory support

Volatile anesthetics help with any bronchospastic component,
but not with expiratory obstruction

Use reduced tidal volumes, slow RR to allow time for expiration
Restrictive pulmonary disease
Primary problem is  lung compliance,  lung volumes, and normal flow indices

Acute intrinsic pulmonary disorders:
o ARDS
o Infectious pneumonia
o Aspiration pneumonitis

Chronic intrinsic pulmonary disorders—cause chronic inflammation of the
alveolar walls and surrounding tissues:
o Interstitial lung diseases
o Hypersensitivity pneumonitis
o Radiation pneumonitis
o Sarcoidosis
o Auto-immune diseases

Extrinsic pulmonary disorders—interfere with lung expansion:
o Pleural effusion
o Pneumothorax
o Mediastinal masses
o Kyphoscoliosis
o Pectus excavatum
o  Abdominal pressure from pregnancy, ascites, or bleeding

Anesthesia management of restrictive lung disease
o Smaller tidal volumes, higher RR
o Maximize gas exchange, minimize hypoxemia
o Diuretics and inotropes for heart failure
o Relieve external pressure if possible