Surgery in the COPD Patient
In patients with COPD and reduced airflow, complication rates vary with the region of the body upon which surgery is performed. The further the procedure from the diaphragm, the lower the risk [1, 2, 9].
In general, these procedures carry a low mortality rate (<1%) . However, cough may be of concern to the ophthalmologist because of increased ocular pressure. Conversely, excessive suppression of cough may lead to retained secretions, atelectasis, pneumonitis and problems in gas exchange. Topical, ophthalmologic, β-blocker medications, used to reduce intraocular pressure, may precipitate bronchospasm and cardiorespiratory failure .
Procedures involving the airway carry an increased risk of postoperative pneumonia .
Management of secretions in the patient who has undergone laryngectomy may require early postoperative humidification.
Orthopedic procedures are associated with a relatively high frequency of venous thromboembolism . In the patient with COPD, pulmonary embolism is associated with greater mortality .
Lower abdominal/pelvic surgery
In general, COPD does not increase the risk of perioperative risk with lower abdominal procedures.
Upper abdominal surgery
Patients who undergo surgery in the upper abdomen are at risk for perioperative pulmonary complications [1, 9]. COPD independently increases this risk . Complications are particularly liable to occur in persons with predisposing factors such as morbid obesity, cigarette smoking, heart disease and advanced age [1, 3].
Laparoscopic procedures appear to decrease perioperative pulmonary complications .
COPD is a common cause of perioperative pulmonary dysfunction in patients undergoing cardiac surgery . Screening for COPD in this patient population is particularly important because COPD has been associated with prolonged intubation after cardiac surgery .
Abdominal vascular surgery
Patients who undergo elective major abdominal vascular surgery are at high risk of postoperative pulmonary complications . Patients with COPD are at particularly high risk . Factors associated with the need for prolonged mechanical ventilation include a history of heavy cigarette smoking, preoperative arterial hypoxaemia and major intraoperative blood loss .
Preoperative pulmonary function studies have a well-documented role in the evaluation of patients who are to undergo lung surgery [18, 19].
Thoracotomy has a reversible (several months) adverse effect on lung function . Thoracoscopy is less invasive and better tolerated than open thoracotomy .
Lobectomy results in an additional ?10% reduction in forced vital capacity (FVC) at 6 months after surgery .
Pneumonectomy usually causes a permanent reduction of about 30% in all lung function. This decrement in lung function can prove devastating to COPD patients .
In select cases, wedge resection, lobectomy or pneumonectomy may actually improve lung function if the resected areas of lung are significantly destroyed by emphysema and the nonresected areas are significantly spared from emphysema (see Lung volume reduction surgery).
If the region resected has no function, then no loss other than that temporary decrement attributable to the thoracotomy should result. This approach forms the basis of the regional physiological assessment of lung function via ventilation or perfusion scintigraphy .
All patients undergoing lung resection should undergo spirometry and determination of diffusing capacity of the lungs . The risk of postoperative respiratory insufficiency or death is greater in patients undergoing a pneumonectomy with a preoperative forced expiratory volume in one second (FEV1) <2 L or 50% of predicted, a maximal voluntary ventilation <50% predicted or carbon monoxide diffusing capacity of the lung <60% predicted .
Patients at high risk for poor outcomes due to poor underlying lung function should undergo further physiological evaluation . The two general areas of evaluation are: 1) regional distribution of lung function; and 2) functional capacity of the patient. An algorithm has been proposed that incorporates these concepts (fig. 1). Although this algorithm has been prospectively validated [23, 24, 26], several issues remain controversial. A second, simpler algorithm has also been proposed, but not validated (fig. 2).
Fig. 1. - A validated algorithm for pre-operative testing for lung resection. ECG: electrocardiogram; FEV1: forced expiratory volume in one second; DL,CO: carbon dioxide diffusing capacity of the lung; V'O2,max: maximum oxygen consumption; ppo: predicted postoperative.
Fig. 2. - A simplified algorithm for pre-operative testing for lung resection. DL,CO: carbon dioxide diffusing capacity of the lung; FEV1: forced expiratory volume in one second; ppo: predicted postoperative; V'O2,max: maximum oxygen consumption.
Lung volume reduction surgery (LVRS) has altered the preoperative assessment for thoracic resection in some of these patients (see Lung volume reduction surgery). Patients with severe pulmonary dysfunction may undergo simultaneous resection of a pulmonary nodule and LVRS [19, 27]. Some patients have successfully had lobectomy in the setting of severe obstructive lung disease [28, 29].
If the patient has cardiovascular risk factors an appropriate cardiovascular evaluation should be undertaken [30, 31].
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