COPD Flashcards
Definition
Os a common preventable and treatable disease. It is characterized by airflow obstruction that is usually progressive and associated with enhanced chronic inflammatory response in the airway and the lung to noxious particles.
Chronic bronchitis and emphysema
The terms are now included within the COPD diagnosis
*Chronic bronchitis: chronic, productive cough for 3 months in each of two successive years in patient whom other causes of cough excluded.
( small airway inflammation causes obstruction and air trapping which results in V/Q mismatch & poor respiratory muscle mechanics.)
*Emphysema:: is a histological diagnosis of a abnormal and permanent enlargement of the airspace distal to the terminal bronchioles without obvious fibrosis.
((Loss of alveolar integrity leads to decrease gas transfer and V/Q mismatch))
Diagnosis of COPD
There is no single diagnostic test for COPD. Diagnosis relies on combination of history,examination and conformation of airflow obstruction using spirometry.
- NICE and GOLD provide guidelines for diagnosis and assessment of COPD
- Diagnosis of COPD should be considered in patient over 35, who have risk factor( generally smoker) and who present with exertional dyspnea, chronic cough, regular sputum production, frequent winter bronchitis or wheeze.
*The presence of airway obstruction should be confirmed with post-bronchodilator spirometry.
Airway obstruction defined by FEV1/FVC <0.7
What are the risk factors???
The most important is cigarettes smoking.
*occupational exposure to dust and atmospheric pollution, poor socioeconomic status, repeated viral infection, alpha 1 antitrypsin deficiency. Genetic factor may be implicated.
Severity assessment??
There is no single test. Degree of airflow obstruction, the level of disability, FEV1, TLCO, the degree of breathlessness, exercise tolerance and BMI
General considerations
- patient with a diagnosis of COPD have an increased risk of perioperative pulmonary complications.
- copd isn’t an absolute contraindication to any surgery.
- The further the procedure from diaphragm the lower the complications rate.
- COpD is associated with other co-morbidities as lung cancer and pulmonary hypertension.
Preoperative assessment
1- preoperative assessment should include a careful history, physical examination and functional capacity.
2- Close attention should be paid to a history of smoking, dyspnea, cough and sputum production.
3- Establish the exercise tolerance
4- Frequency of exacerbation, timing the most recent course of antibiotics and hospital admission and previous requirement of invasive and non-invasive ventilation.
5- assess the nutritional status. Poor nutritional status with serum albumin <30g/dl is a strong predictor fo postop complication.
6- Decreased breath sounds, prolonged expiration, and wheeze are predictive of postop respiratory complications.
7- surgery should if possible, be postponed and appropriate ttt started if symptoms of an active respiratory infection found.
What are the investigations???
1-preop spirometry if clinical evaluation cannot determine whether the patient is at their best baseline and the airflow obstruction is optimally reduced. It also aid severity of COPD.
2- Check ABGs in moderate to severe COPD. Useful to determine post-op respiratory parameters.
3- ECG may reveal RV hypertophy or strain.consider echo.
4- CXR is not mandatpry. Ot should be considered of there evidence of current infection or recent deterioration in symptoms.
Preoperative optimization
*Every effort should be made to assist patients in stopping smoking.
Smoking cessation at least 8 wks is optimal.
*All patients with symptomatic COPD receive daily inhaled ipratropium.
- Inhaled b2 agonist should be used, as needed, for symptoms and wheezing in preop period.
- Continue patients’ usual inhaled medication.
- Patients with persistent wheeze and functional limitation despite bronchodilator should be treated with glucocorticoids and to be seen by respiratory physician.
- If patients have severe COPD, postop respiratory failure is likely after abdominal or upper thoracic surgery. Plan for elective ICU admission.
- Consider preop physiotherapy in ptnt with copious sputum production.
- Consider the need fro preop nutritional supplementation.
Conduct of Anaesthesia
- gA, and in particular tracheal intubation and IPPV, is associated with adverse outcomes in patients with COPD. Such patients are prone to bronchospasm, laryngospasm, CVS instability, barotrauma, hypoxaemia, and increased rates of post-operative pulmonary complications.
- Consider avoiding gA by using a regional anaesthetic technique, where possible. this may be limited by some patients’ inability to lieflat.
- Consider using an arterial line for both beat-to-beat BP analysis and repeated blood gas analysis.
- Where gA cannot be avoided, preoxygenation should be used in any patient who is hypoxic on air prior to induction.
- Avoid intubation where possible. Some patients, however, are unsuitable for a spontaneously breathing technique (particularly those who are obese, breathless, and require long operations). Patients with heavy sputum production may benefit from endotracheal toilet.
- If using IPPV, consider using PEEP and allowing more time for exhalation by decreasing the respiratory rate or the I:E ratio (typically 1:3–1:5). these approaches may help to reduce air trapping and the development of intrinsic PEEP, both of which can cause an increase in intrathoracic pressure, which can lead to CVS instability. Harmful effects of air trapping include pulmonary barotrauma, hypercapnia, and acidosis.
- Ensure the neuromuscular agent is fully reversed, the patient is warm and well oxygenated, and has a PaCO2 close to the patient’s normal preoperative values prior to extubation.
- Extubate in the sitting position.
- Bronchodilator treatment may be helpful peri-extubation.
- Extubation of the high-risk patient directly onto non-invasive ventilation may reduce the work of breathing and air trapping
Postoperative care
- those patients with severe disease or significant co-morbidities should be managed in a high-dependency setting capable of regular ABg measurements and the provision of non-invasive ventilation.
- Hypoventilation as a result of residual anaesthesia or opioids should be avoided, as this may lead to hypercapnia and hypoxia.
- Encourage early mobilization.
- Use of saline nebulization, suctioning, and physiotherapy are useful to prevent atelectasis and to encourage sputum production
- Continue with nebulized salbutamol (2.5mg qds) and ipratropium (500 micrograms qds) until fully mobile. Change back to inhalers at least 24hr before discharge.
- Effective analgesia is a significant determinant of post-operative pulmonary function. Epidural anaesthesia is an attractive option, as it reduces the risk of respiratory failure because of excessive sedation from opioids. It should therefore be considered, if appropriate
