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* From the Division of Pulmonary and Critical Care Medicine, Stanford University Medical Center, Stanford, CA.
Correspondence to: Ramona L. Doyle, MD, FCCP, Stanford University Medical Center, Division of Pulmonary/Critical Care Medicine, H3147, Stanford, CA 94305-5236
| Abstract |
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| Introduction |
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Identifying patients at risk for pulmonary complications is the first step. The second, and perhaps more perplexing step, is figuring out how, or if, that risk once identified can be impacted. In the extreme, risk modification may involve canceling an operation, but clearly the type of operation planned, whether it is emergent or elective, the surgical site, and the fitness of the patient must influence this decision. Modifying the risk of postoperative pulmonary complications may involve anything from postponement of surgery and changes in the planned anesthetic technique to simple instructions to patients (ie, stop smoking, lose weight) and the educated use of simple interventions (eg, bronchodilators and incentive spirometry).
| Identifying Risk Factors |
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The anatomic site of surgery is significant in the development of postoperative pulmonary complications.2 11 Abdominal surgery appears to pose a particularly high risk for pulmonary complications. Pulmonary complications have been reported in 20 to 70% of patients undergoing upper abdominal and thoracic operations3 12 13 14 compared with a 4% incidence of pulmonary complications after urologic or orthopedic surgery.15 In one study, the pulmonary complication rate for all abdominal operations was 10.3% compared with a rate of 0.6% for nonabdominal and nonthoracic operations.14 One study showed the rate of postoperative pulmonary complications to be 25% for upper abdominal incisions vs 19% for thoracotomies.3 In thoracic resection, the complication rate relates to the amount of functional lung that has been resected.16 While risk based on site of operation might seem relatively immutable, newer operative techniques may change this. The use of laparoscopic techniques in particular may enhance recovery and reduce the risk of pulmonary complications by causing less pain and less disruption of abdominal and diaphragmatic muscle activity and allowing for more rapid recovery following an operation.17 18
The duration of anesthesia19
20
also has been shown to be
an independent predictor of postoperative pulmonary
complications.8
21
Postoperative pneumonia is more common
in operations lasting
4 h regardless of the site of
operation.2
Improvements in anesthetic techniques,
including the use of regional vs general anesthesia,22
better postoperative pain management,23
and the use
anesthetic agents with shorter elimination half-lives24
may decrease the risk of many surgical procedures.
Patient Characteristics and Assessment of Pulmonary Function
Although age alone does not confer an independent risk of
postoperative pulmonary complications,2
the fastest
growing group of patients with cardiopulmonary disease is the
elderly.25
The number of surgical procedures in elderly
patients is on the rise and thus patient age may represent a
recognizable if unalterable risk. Elderly patients have generally
higher rates of treatment-related risks and also have a shorter life
expectancy, thus the risk of surgery may compete more closely with the
risk of not performing surgery in this group of
patients.26
Chronic lung disease poses the most significant patient-related risk for post-operative pulmonary complications. Distinguishing patients with lung disease from those without it is an important step in identifying the risk of postoperative pulmonary complications. Pulmonary function tests can assess the presence and the severity of lung disease, but the ability of different tests of pulmonary function to predict pulmonary complications has been variable. In terms of identifying patients with lung disease, minimal changes in pulmonary function test results alone may be no more sensitive as indicators of occult pulmonary disease than the information gathered from a careful history and physical examination.27 Thus, the wholesale use of pulmonary function tests as a preoperative screen for the presence of pulmonary disease in patients without a suggestive clinical history or examination is unwarranted. And in this circumstance, pulmonary function tests are of limited use in predicting individual outcomes. However, in patients undergoing lung resection, pulmonary function tests serve to establish a baseline from which to estimate the impact of surgery on respiratory function.
In patients with known underlying pulmonary disease such as COPD and asthma, pulmonary function tests can estimate disease severity and prompt interventions that may reduce risk. COPD patients have an overall increased rate of postsurgical complications that may range from 26 to 78%3 13 ; thus, pulmonary function test results may identify patients who are at a prohibitively high risk of postoperative mortality. Patients with asthma who are symptomatic at the time of surgery have an increased risk of morbidity from anesthesia28 ; thus, it is ideal that surgery be performed in asthmatic patients when they are symptom free.
Measurement of arterial blood gases is indicated in patients with lung disease prior to surgery for two reasons. First, patients with hypercapnia have been found to have an increased incidence of postoperative pulmonary complications in several series13 16 29 and, secondly, the development of hypercapnia in patients with COPD is associated with a shortened life expectancy independent of the risk of surgery.30 Persistently elevated PaCO2 values of > 45 mm Hg predict a high risk for pulmonary complications or death.9 16 Arterial hypoxemia (PaO2 < 50 mm Hg) may also be a relative contraindication to surgery. While a high PaCO2 or low PaO2 may not absolutely contraindicate surgery, they can highlight the necessity of providing intense and careful preoperative support in high-risk patients. Nevertheless, the risk of an elective surgery in patients with severe lung disease, hypoxemia, and hypercapnia may in some instances prove to be unacceptable.
In high-risk patients undergoing pneumonectomy (those with an FEV1 < 2 L) in addition to full pulmonary function tests, postoperative lung function should be estimated by split-perfusion lung scanning.31 A predicted postoperative FEV1 of > 80 mL has been associated with an operative mortality of approximately 15%, but it is believed to represent an acceptable cutoff for reasonable postoperative pulmonary function.27
A chest radiograph is a type of preoperative assessment of pulmonary function. Just as pulmonary function tests are rarely abnormal in patients without risk factors for lung disease,32 33 chest radiographs rarely reveal anything that might change the decision to perform an operation in patients without other risk factors. A chest radiograph is indicated in patients with evidence of new or changing lung disease or in patients believed to be at high risk for pulmonary complications.
| Reducing the Risk |
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Smoking Cessation
The risk of developing postoperative pulmonary complications has
been shown to decrease significantly after 8 weeks of smoking
cessation,35
and it is increased in patients who continue
to smoke.14
16
20
This time period correlates with the
time it takes for improvements in tracheobronchial clearance and small
airway function. Heavy smokers have a higher rate of pulmonary
complications than patients who have smoked less, and heavy smokers
tend to have significantly increased levels of carboxyhemoglobin that
can cause decreases in arterial
PaO2.36
The half-life for
carboxyhemoglobin is approximately 6 h; therefore, there is a
theoretical, if unproven, benefit to advising all patients,
particularly heavy smokers, that smoking cessation, even a day before
surgery, may be worthwhile.
Obesity
Overall life expectancy is decreased in obese
patients,37
but surgical mortality has not been shown to
be increased.38
Obese patients, however, are at increased
risk for postoperative pulmonary complications such as
atelectasis.20
In one study, a loss of
9 kg even in a
patient remaining 23% above ideal body weight was shown to lower the
risk of pulmonary complications.39
In the case of the
morbidly obese patient, delaying surgery until some weight loss can be
achieved will likely reduce the risk of postoperative complications.
Chest Physiotherapy
Several therapies that can be loosely classified as chest
physiotherapy have been studied in relation to their ability to reduce
postoperative pulmonary complications. These therapies have included
deep breathing exercises in conjunction with chest percussion and
postural drainage,40
perioperative intermittent positive
pressure breathing,3
13
and incentive
spirometry.41
As adjuncts to postoperative care, these
therapies appear to be of some benefit in reducing pulmonary
complications but are essentially of equivalent efficacy. Given the
relatively low cost and simplicity of self-administered incentive
spirometry, it is likely that incentive spirometry is the most
reasonable intervention among these therapies for reducing the risk of
pulmonary complications. It is important to note that preoperative
instruction in the use of incentive spirometry is key to its effective
use by the patient after surgery.
Antibiotics, Bronchodilators, and Steroids
Although 50% of the pneumonias diagnosed in hospital are in
surgical patients,2
prophylactic antibiotic use in
patients facing surgery should be reserved for patients with evidence
of infected sputum.13
In patients with COPD and an
increased cough with phlegm, a 10-day course of antibiotic therapy may
reduce the risk of postoperative pneumonia.2
Elective
surgical procedures should be delayed until a full course of antibiotic
therapy is concluded in such patients.
In patients with symptomatic COPD and asthma, bronchodilators and steroids can prevent bronchospasm and reverse any reversible component of ongoing bronchospasm.36 ß-Agonist medications are the first-line medications and can be administered via nebulizer or metered-dose inhaler. In one study of patients with COPD, those given a preoperative conditioning regimen, which included bronchodilators, had fewer postoperative pulmonary complications than historical control subjects.3 Another prospective study found that the use of bronchodilators and steroids decreased the risk of postoperative pneumonia in patients with COPD.2 In symptomatic asthmatic patients and patients with severe COPD, steroids may be beneficial,42 but they should be given at least 12 h before the operation because they can take > 6 h to take effect. If steroids are given, they should be given in high doses for only a few days and then tapered gradually over the first postoperative week or longer. The pace of the taper will depend largely on the patients history of lung disease and the role steroids have played in it, as well as on their postoperative course. In addition to being a good bronchodilator, theophylline has been shown to improve respiratory muscle function.43 Its use preoperatively as a bronchodilator should be limited to patients in whom it has been of proven benefit and/or those in whom severe bronchospasm persists despite the optimal use of inhaled bronchodilators and steroids.
| Conclusion |
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| References |
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This article has been cited by other articles:
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G. Varela, E. Ballesteros, M. F. Jimenez, N. Novoa, and J. L. Aranda Cost-effectiveness analysis of prophylactic respiratory physiotherapy in pulmonary lobectomy Eur. J. Cardiothorac. Surg., February 1, 2006; 29(2): 216 - 220. [Abstract] [Full Text] [PDF] |
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J. Weindler and R.-T. Kiefer The Efficacy of Postoperative Incentive Spirometry Is Influenced by the Device-Specific Imposed Work of Breathing Chest, June 1, 2001; 119(6): 1858 - 1864. [Abstract] [Full Text] [PDF] |
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