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
  • Diaphragm dysfunction
  • FRC  60% after upper abdominal surgery, lasts 7 days
  • Rapid shallow breathing with ineffective cough
  • Impaired muco-ciliary clearance
  • 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.
  • Air trapping and prolonged expiratory times due to elevated resistance to airflow
  • Noisy breathing (wheezing, ronchi) due to turbulent air flow
  •  Work of Breathing
  • Impairment of respiratory gas exchange
  • FEF 25-75 <70%; later FEV1 and FEV1/FVC <70%
  • Asthma
  • Main problem is airway inflammation and hyper-reactivity
  • Airway obstruction results from bronchial smooth muscle constriction, airway edema, and  secretions
  • Symptoms: wheezing, dyspnea, coughing
  • Signs: delayed rise in CO2 during expiration on capnograph, indicating airflow obstruction,  peak inspiratory pressures and incomplete exhalation when obstruction is severe.
  • 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

  • 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
  • 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”)
  • 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:
  • ARDS
  • Infectious pneumonia
  • Aspiration pneumonitis
  • Chronic intrinsic pulmonary disorders—cause chronic inflammation of the alveolar walls and surrounding tissues:
  • Interstitial lung diseases
  • Hypersensitivity pneumonitis
  • Radiation pneumonitis
  • Sarcoidosis
  • Auto-immune diseases
  • Extrinsic pulmonary disorders—interfere with lung expansion:
  • Pleural effusion
  • Pneumothorax
  • Mediastinal masses
  • Kyphoscoliosis
  • Pectus excavatum
  •  Abdominal pressure from pregnancy, ascites, or bleeding
  • Anesthesia management of restrictive lung disease
  • Smaller tidal volumes, higher RR
  • Maximize gas exchange, minimize hypoxemia
  • Diuretics and inotropes for heart failure
  • Relieve external pressure if possible