You are in: eMedicine Specialties > Perioperative Care > Perioperative Care Perioperative Pulmonary ManagementArticle Last Updated: Jun 30, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Sat Sharma, MD, FRCPC, Professor and Head, Division of Pulmonary Medicine, Department of Internal Medicine, University of Manitoba; Site Director, Respiratory Medicine, St. Boniface General Hospital Sat Sharma is a member of the following medical societies: American Academy of Sleep Medicine, American College of Chest Physicians, American College of Physicians-American Society of Internal Medicine, American Thoracic Society, Canadian Medical Association, Royal College of Physicians and Surgeons of Canada, Royal Society of Medicine, Society of Critical Care Medicine, and World Medical Association Editors: Helen M Hollingsworth, MD, Director, Adult Asthma and Allergy Services, Associate Professor, Department of Internal Medicine, Division of Pulmonary and Critical Care, Boston Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Donna Leco Mercado, MD, Director of Medical Consultation, Department of Internal Medicine, Baystate Medical Center; Assistant Professor, Tufts University School of Medicine; Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine; William A Schwer, MD, Professor, Department of Family Medicine, Rush Medical College; Chairman, Department of Family Medicine, Rush-Presbyterian-St Luke's Medical Center Author and Editor Disclosure Synonyms and related keywords: pulmonary complications, ventilation management, perioperative morbidity, perioperative mortality, atelectasis, bronchitis, pneumonia, prolonged mechanical ventilation, respiratory failure, chronic lung disease, bronchospasm, adverse effects of anesthesia, diaphragm dysfunction, diaphragmatic dysfunction, chronic obstructive pulmonary disease, COPD, PE, pulmonary embolism, DVT, deep vein thrombosis, deep venous thrombosis BACKGROUNDSection 2 of 11
  Postoperative pulmonary complications contribute significantly to overall perioperative morbidity and mortality rates. Pulmonary complications occur much more often than cardiac complications in patients undergoing elective surgery to the thorax and upper abdomen. The frequency rate of these complications varies from 5-70%. Postoperative pulmonary complications prolong the hospital stay by an average of 1-2 weeks. Postoperative pulmonary complication is defined as an abnormality that produces identifiable disease or dysfunction, is clinically significant, and adversely affects the clinical course. Complications may arise from atelectasis, infection (eg, bronchitis, pneumonia), prolonged mechanical ventilation and respiratory failure, exacerbation of an underlying chronic lung disease, and bronchospasm. Several published studies include complications that have no clinical significance. However, recent studies define postoperative pulmonary complications as the events influencing outcome following surgery. These include complications either known to prolong the hospital stay or known to be responsible for morbidity and mortality. PERIOPERATIVE PULMONARY PHYSIOLOGYSection 3 of 11
Respiratory effects of general anesthesia Anesthetic agents are associated with marked alterations in respiratory drive. Agents cause a diminished response to both hypercapnia and hypoxemia. In combination with neuromuscular blockers, anesthetic agents cause diaphragm and chest wall relaxation, which results in a marked reduction in the functional reserve capacity and, thereby, thoracic volume. This decrease in lung volume promotes atelectasis in the dependent lung regions and persists for more than 24 hours in 50% of patients. Consequently, arterial hypoxemia occurs from ventilation perfusion mismatch and increased shunt fraction. Postoperative respiratory physiology in upper abdominal and thoracic surgery Thoracic and upper abdominal surgery is associated with a reduction in vital capacity by 50% and functional residual capacity by 30%. Diaphragmatic dysfunction, postoperative pain, and splinting cause these changes. Following upper abdominal surgery, patients shift to a breathing pattern with which ribcage excursions and abdominal expiratory muscle activities increase. This shift is attributed to decreased central nervous system output to the phrenic nerves, thus inhibiting diaphragmatic stimulation. A reflex mechanism arising from the sympathetic, vagal, or splanchnic receptors is thought to be responsible. In humans, this reflex inhibition is partially reversed by epidural anesthesia. Following upper abdominal and thoracic surgery, patients maintain adequate minute volume, but the tidal volume is smaller and the respiratory rate increases (ie, rapid shallow breathing). These breathing patterns, along with the residual effects of anesthesia and postoperative narcotics, inhibit cough, impair mucociliary clearance, and contribute to the risk of postoperative pneumonia. Other factors that may contribute to increased respiratory complications include electrolyte imbalance (eg, hypokalemia, hypophosphatemia, hypocalcemia), general debilitation, and underlying lung disease (eg, chronic obstructive pulmonary disease [COPD]). PATIENT- AND PROCEDURE-RELATED RISK FACTORSSection 4 of 11
Patient-related risk factorsAge Despite early suggestions of an increased risk of pulmonary complications with advanced age, this is not an independent risk factor for pulmonary complications. In a study of patients older than 80 years, the overall 30-day mortality rate was 6.2% and the mortality rate for patients who belonged to American Society of Anesthesiologists (ASA) class II was less than 1% (Djokovic, 1979). Several other studies have shown that age is not a predictor for postoperative pulmonary complications; therefore, surgery should not be declined because of advanced age alone. Obesity Obesity decreases the expiratory reserve volume and functional residual capacity of lungs; morbid obesity causes restrictive lung disease, decreases thoracic compliance, and leads to alveolar hypoventilation. In severe cases, obesity is associated with pulmonary hypertension, cor pulmonale, and hypercapnic respiratory failure (pickwickian syndrome). Obesity causes a reduction in lung volume, ventilation-perfusion mismatch, and relative hypoxemia, which are accentuated after surgery. Obesity (ie, body mass index of >27 kg/m2) increases the risk of postoperative pulmonary complications and respiratory failure in patients undergoing abdominal surgery, but it may not be a risk factor in thoracic surgery. In a recent review article (Smetana, 1999), the risk of postoperative pulmonary complications was not excessive in 7 studies of obese patients who underwent abdominal or peripheral procedures. Several other studies have also reported no association between obesity and postoperative pulmonary complications. Another recent study (Phillips, 1994) did not report excessive pulmonary complications in individuals who were obese and underwent laparoscopic cholecystectomy. General health status The ASA classification and the Goldman Cardiac Risk Index have helped successfully predict pulmonary risk. Patients who have poor exercise capacity are at increased risk of developing postoperative pulmonary complications. In a study by Gerson et al in 1990, an inability to raise the heart rate with simple exercise predicted a pulmonary complication rate of 79%. Smoking Patients who currently smoke have a 2-fold increased risk of postoperative complications, even in the absence of COPD. The risk is highest in patients who smoked within the last 2 months. Patients who quit smoking for more than 6 months have a risk similar to those who do not smoke. In 1989, Warner et al prospectively investigated the role of preoperative smoking cessation on postoperative pulmonary complications in patients undergoing coronary artery bypass surgery. Those who currently smoked developed postoperative complications at a rate of 33%, compared with 57% for individuals who quit for less than 8 weeks. The complication rates were 11.9% in persons who never smoked and 14.5% in patients who had quit for more than 8 weeks. Postoperative morbidity was not decreased in patients who quit smoking for less than 8 weeks. The beneficial effects of smoking cessation, including improvement in ciliary and small airway function and a decrease in sputum production, occur gradually over several weeks. The increased incidence of postoperative complications in patients who recently stopped smoking has not been shown in other studies. The likely mechanism is that abrupt absence of the irritant effect of cigarette smoke in the postoperative period inhibits coughing and leads to retention of secretions and small airway obstruction. Chronic obstructive pulmonary disease This is one of the most important risk factors. Patients with severe COPD (forced expiratory volume in 1 s [FEV1] <40% predicted) are 6 times more likely to have a major postoperative complication. Despite the increased risk, a prohibitive level of pulmonary function for an absolute contraindication is not apparent. The benefits of surgery must be weighed against these complications. A careful preoperative evaluation of patients with COPD should include identification of high-risk patients and aggressive treatment. Elective surgery should be deferred in patients who are symptomatic, have poor exercise capacity, or have acute exacerbation. Asthma Inadequate control of asthma preoperatively may increase the risk of postoperative complications. Optimal asthma control is defined as the absence of symptoms and an FEV 1 of more than 80% of predicted or personal best. Sleep apnea Patients with sleep apnea are at increased risk of developing deterioration of sleep disordered breathing, severe hypoxemia, and hypercapnia in the postoperative period. Individuals with sleep apnea who are also obese may present difficulties with endotracheal intubation or early postoperative upper airway obstruction, requiring reintubation or other therapies. In patients with known or possible sleep apnea, the intraoperative and postoperative use of sedatives and narcotics should be minimized. Careful monitoring in the postoperative period is required for worsening of sleep apnea, development of airway obstruction, or carbon dioxide retention. In patients who may have sleep apnea, the diagnosis should be confirmed and the severity should be assessed preoperatively with a formal polysomnographic sleep study. The severity of sleep apnea is judged based on the apnea-hypopnea index and the lowest oxygen saturation value during sleep. Whenever possible, patients should be adequately treated with nasal continuous positive airway pressure (CPAP) therapy preoperatively. Further, patients with sleep apnea often benefit from regional anesthesia rather than general anesthesia. Procedure-related risk factorsSurgical site The incidence of complications is inversely related to the distance of the surgical incision from the diaphragm. The complication rates for upper abdominal surgery range from 17-76%. For lower abdominal surgery, the rate is 0-5%. For thoracic surgery, the rate is 19-59%. Laparoscopic cholecystectomy is associated with a lower incidence of complications; the mean decrease in forced vital capacity (FVC) was reported at 23%, as compared to 50% with laparotomy. Duration of surgery Patients undergoing procedures lasting longer than 3-4 hours have a higher incidence rate of pulmonary complications compared to those undergoing surgeries lasting shorter than 2 hours (40% vs 8%). Type of anesthesia Data are inconsistent about whether the complication rate is lower with spinal or epidural anesthesia compared to general anesthesia. A study published in 1984 (Celli, 1984) reported no difference in patients anesthetized with spinal or general anesthesia for abdominal surgery. A study of high-risk patients shows that the rate of respiratory failure is significantly higher with general anesthesia (Tarhan, 1973). Several other studies (Yeager, 1987; Pedersen, 1990) found high rates of respiratory failure and other postoperative complications in patients undergoing general anesthesia compared to spinal or epidural anesthesia. The spinal or epidural anesthesia is safe and should be considered in high-risk patients. Regional nerve block is associated with a low risk and should be considered whenever possible for high-risk patients. Keyhole surgery Laparoscopic abdominal surgery, particularly the cholecystectomy, is associated with fewer postoperative pulmonary abnormalities and a shorter hospital stay. These techniques use small incisions, and the reduced manipulation of visceral organs minimizes the adverse effects on respiratory muscles. Laparoscopic surgery leads to a 23% decrease in FVC and a 16% decrease in FEV1 (Torrington, 1996); therefore, patients with severe COPD can tolerate surgery. Video-assisted thoracoscopic surgery uses much smaller incisions; consequently, the hospitalization time is substantially reduced. Smaller incisions, performed without separation of the ribs and resulting in less postoperative pain, lead to early ambulation and reduced pulmonary complications. PREOPERATIVE RISK ASSESSMENTSection 5 of 11
HistoryObtain a complete history and perform a complete physical examination to help identify risk factors. Seek any history of smoking, exercise intolerance, unexplained dyspnea, or cough. Note evidence of COPD, such as decreased breath sounds, wheezes, crackles, or a prolonged expiratory phase. WorkupPulmonary function tests Several retrospective studies of routine preoperative pulmonary function test (PFT) results found only a marginal benefit in predicting postoperative complications in patients, other than those undergoing lung resection. Therefore, the results from PFTs should not be the sole reason to alter plans for necessary surgery. These could be used to identify high-risk patients for whom aggressive perioperative management is warranted. The American College of Physicians consensus statement suggests the following indications for preoperative PFTs:
Additionally, indications for preoperative PFTs have been suggested as follows:
Data from studies by Kroenke et al (1993) and Wong et al (1995) led to the conclusion that patients with severe COPD, classified as very high risk, may undergo surgery and will have a moderate risk of postoperative complications (29%). PFT results do not help identify either the high-risk patients or the severity of dysfunction when the risk of surgery is forbidding. Therefore, surgery should never be withheld based on results from PFTs. Spirometry Bedside spirometry is an often underused but extremely useful tool for objectively evaluating the respiratory status of patients preoperatively. Spirometry can be used to predict postoperative complications and to guide optimization of airflow obstruction in preparation for surgery. Gass and Olsen (1986) suggested high postoperative risk in patients who had an FEV1 of less than 70% predicted, an FVC of less than 70% predicted, and FEV1-to-FVC ratio of less than 65%. Arterial blood gases A PaCO2 of more than 45 mm Hg often occurs in persons with severe COPD and indicates a high risk, although it is not necessarily prohibitive for surgery. Hypoxemia is not a significant predictor of complications. Patients undergoing cardiac or abdominal surgery who have dyspnea or who smoke and patients undergoing thoracic surgery should have arterial blood gas analyses. Chest radiograph Chest x-ray studies add little to the clinical evaluation in healthy patients. Preoperative chest x-ray is the most frequently ordered radiological test. A systematic review of the literature on the value of screening chest x-rays to establish evidence to support guidelines for its use was recently performed. Out of this review, 14 studies met both inclusion criteria and exclusion criteria and identified chronic disorders, such as cardiomegaly and chronic obstructive pulmonary disease, in up to 65%. The rate of subsequent investigations was highly variable (4-47%). The findings led to a change in management in 10% of investigated patients. Postoperative pulmonary complications were also similar between patients who had preoperative chest x-rays (12.8%) and patients who did not (16%). The current recommendation from the Guidelines Association Committee that routine chest x-rays should not be performed routinely for preoperative evaluation in patients without risk factors is supported by this study (Joo et al, 2005). Risk indicesPulmonary Risk Index/Cardiopulmonary Risk Index A combined Cardiopulmonary Risk Index is proposed for risk stratification of pulmonary complications. Pulmonary risk factors have been added to the Goldman Cardiac Risk Index; patients with a combined score of greater than 4 points (out of a total of 10) are 17 times more likely to develop complications. These pulmonary risk factors include the following:
Lawrence Risk Index The test to determine this index is based on clinical information such as abnormal findings from the physical examination chest radiograph. This index needs further validation in prospective studies. American Society of Anesthesiology classification This score is based on simple clinical criteria and is easy to quantify. Although subjective, a score of 2-5 indicates an increased level of severity and increased postoperative morbidity. The ASA classification, along with examples of each class, is described below:
A systematic review of the performance of variables commonly used in the prediction of postoperative pulmonary complications in patients undergoing nonthoracic surgery was performed. Seven studies fulfilled the inclusion criteria, and the incidence of postoperative pulmonary complications varied from 2-19%. Of the 28 preoperative or operative risk factors that were evaluated in the 7 studies, 16 were associated significantly with postoperative pulmonary complications. Only 2 (duration of anesthesia and postoperative nasogastric tube placement) were significant in more than one study. However, these 16 variables had only modest predictive value. Neither hypercarbia nor reduced spirometry values were independently associated with an increased risk of postoperative pulmonary complications (Fisher et al, 2002). A prospective cohort study where postoperative pulmonary complications ascertained by an investigator blinded to perioperative variables was conducted to determine the risk factors for pulmonary complications after elective nonthoracic surgery. Of 1055 consecutive patients, 28 (2.7%) suffered a postoperative pulmonary complication within 7 days of surgery; 13 developed respiratory failure requiring ventilatory support; 9 developed pneumonia; 5 developed atelectasis requiring bronchoscopic intervention; and 1 developed pneumothorax requiring intervention. Multivariate analyses revealed that 4 were independently associated with increased risk of pulmonary complications: age (odds ratio [OR] 5.9 for age 65 years or older), positive cough test (OR 3.8), perioperative nasogastric tube (OR 7.7), and duration of anesthesia (OR 3.3 for operations lasting at least 2.5 h) (McAlister et al, 2005). PREOPERATIVE EVALUATION: THORACIC SURGERYSection 6 of 11
Preoperative evaluation - Lung resection Surgical resection remains the only potential curative therapy for patients with localized non–small-cell lung cancer. These patients often have COPD from a long history of smoking. Development of COPD is considered a risk factor for bronchogenic carcinoma. The first successful pneumonectomy for the treatment of lung cancer was performed by Graham and Singer in 1933. Complete resection of stage I and II non–small-cell lung cancer is associated with a 5-year survival of rate approximately 70%. The overall 5-year survival rate from lung cancer is dismal, at 14%. Hence, every patient with limited lung cancer should be rigorously evaluated for potential resectability and cure. Preoperative assessment helps identify patients at greatest risk for postoperative complications and those patients with severe impairment, in whom surgery is prohibitive. A multicenter study found an in-hospital patient mortality rate of 3.8% after wedge resection, 3.7% after segmental resection, 4.2% after lobectomy, and 11.6 % after pneumonectomy (Romano, 1992). The significant predictors of mortality were age older than 60 years, extended resection, chronic heart or lung disease, and low FEV1. Some suggest measuring preoperative pulmonary function, the calculation of predicted postoperative pulmonary function, gas exchange, and exercise capability. Preoperative pulmonary function FEV1 is the primary value used to determine resectability. FEV1 predicts pulmonary reserve and is a strong predictor of postoperative complications. For full pneumonectomy, a preoperative FEV1 of greater than 2 L/s is required, whereas the suggested threshold value for lobectomy is 1 L/s. In female patients, absolute numbers may be less helpful than percent predicted values. Measuring diffusion capacity is a noninvasive method to assess pulmonary circulation. Findings reflect the volume of the pulmonary capillary bed. Diffusion capacity is reportedly a good predictor of morbidity and mortality after lung resection. A diffusion capacity of below 60% predicted is associated with a patient mortality rate of 24%. A diffusion capacity of less than 40% with borderline FEV1 values is associated with high mortality and morbidity, and surgery may be prohibitive (Markos, 1989). Linden et al (2005) conducted a study to determine the morbidity, mortality, and feasibility of lung resection in patients with tumors and a preoperative FEV1 of less than 35% predicted. One hundred consecutive patients with respectable lung tumors and with a preoperative FEV1 of less than 35% predicted and surgery for curative intent were included. Average preoperative predicted FEV1 was 26%; 16% were oxygen dependent preoperatively. Minimally invasive surgical techniques and intensive pulmonary care resulted in a very low mortality and a very low incidence of ventilator dependence. Other serious complications, such as pneumonia, myocardial infarction, and bleeding, are uncommon, but an extended hospital stay and a high incidence of prolonged air leak should be expected. Postoperative pulmonary function can be predicted using the following formula: Predicted postoperative function = (preoperative function) X (percent of function contributed by the lung that will remain postoperatively) This measurement should improve the predictive value of preoperative testing. Based on a combination of spirometry and quantitative perfusion lung scan findings, a predicted postpneumonectomy FEV1 of greater than 0.8 L/s is suggested as the lower limit. A postpredicted FEV1 of greater than 0.8 L/s as a measure of resectability is based on a study by Segall and Butterworth (Segall, 1966) that showed hypercapnia (PaCO2 >45 mm Hg) developed in patients with an FEV1 of less than 0.8 L/s. The percentage of predicted value is a better measure because it reflects differences in size, age, sex, and race. The predicted postoperative FEV1 of 40% or more is associated with the least mortality. A predicted FEV1 of 40% predicted is required for performance of minimal activities of daily living without dyspnea. Lung resection leaving the patient with a lower functioning lung certainly leads to a respiratory invalid. FEV1 of less than 30% is associated with a survival rate of 20-30%. Therefore, a decline in the postoperative FEV1 to less than 30% not only causes immediate postoperative morbidity and mortality but also results in excessive longer-term mortality. Radionuclide lung scanning is required to help calculate this value. If the predicted postoperative FEV1 is less than 0.8 L/s or less than 40% predicted, the patient is unresectable. Radionuclide quantitative lung scanning is used extensively in the evaluation of possible pulmonary embolism. This technique has also been used to quantitate the function of a lung or a lobe that will be resected. Therefore, the function of the remaining lung can be calculated. Olsen et al (Olsen, 1974) reported that a postpneumonectomy FEV1 of less than 0.8 L/s was associated with prohibitive risk. Another study concluded that a predicted postoperative FEV1 of greater than 0.8 L/s resulted in acceptable survival following pneumonectomy. A threshold value of predicted postoperative FEV1 of 35% is suggested (Gass, 1986), but this has not been tested either retrospectively or prospectively. Measurement of gas exchange Gas exchange is assessed by measuring the diffusing capacity and arterial blood gas values. High morbidity and mortality have been associated with a postoperative diffusion capacity of less than 40% predicted. A low resting PaO2 is not a strong predictor, but hypercapnia (PaCO2 >45 mm Hg) has been considered a significant risk factor, although not proven. Exercise testing A comprehensive physiologic evaluation is dependent on the interaction among pulmonary function, cardiovascular function, and oxygen use. This may take the form of stair climbing or complete cardiopulmonary exercise testing. Values from stair climbing tests, although poorly standardized, have been shown to help identify patients at increased risk for lung resection. Patients capable of climbing 3 or more flights of stairs have lower complication rates. Complete cardiopulmonary exercise testing may help identify patients who achieve a maximal oxygen consumption (VO2 max) of less than 1 L/min. These patients have high mortality rates. Expressing VO2 max as mL/kg may be more useful. A VO2 max of more than 20 mL/kg/min is associated with the fewest postoperative complications, whereas a value of less than 10 mL/kg/min may be prohibitive because of the high morbidity and mortality rates. The patients who exercise to a VO2 max of 10-20 mL/kg/min may have an increased but acceptable risk. Several different studies have established that perioperative complications can be predicted by stratifying preoperative VO2 max. Patients with a VO2 max of greater than 20 mL/kg/min are not at an increased risk of complications or death; a VO2 max of less than 15 mL/kg/min indicates an increased risk of perioperative complications; and patients with a VO2 max of less than 10 mL/kg/min have a very high risk for postoperative complications. Alternative types of exercise testing include stair climbing, the shuttle walk, and the 6-minute walk. Although often not performed in a standardized manner, stair climbing can predict a VO2 max. In general terms, patients who can climb 5 flights of stairs have a VO2 max of greater than 20 mL/kg/min; the patients who cannot climb 1 flight of stairs have a VO2 max of less than 10 mL/kg/min. Evidence on the shuttle walk and 6-minute walk is limited, but patients who cannot complete 25 shuttles on 2 occasions will have a VO2 max of less than 10 mL/kg/min. Desaturation during an exercise test has been associated with an increased risk for perioperative complications. Caution: Patients who do not meet these criteria should not be summarily refused surgery if they are willing to accept the possibility of earlier death or prolonged disability over the certainty of cancer death. Preoperative evaluation - Cardiac surgery The incidence of left lower lobe atelectasis has been reported in up to 90% of patients, which may increase the postoperative morbidity and prolong the hospital stay. The incidence is attributed to phrenic nerve injury and may last from 30 days to 2 years. Operative factors associated with this complication are a longer bypass time, entrance into the pleural cavity, direct injury during mobilization of the internal mammary artery, and cold cardioplegia. The overall incidence of pulmonary complications after coronary bypass surgery is 7.5%. Patients with abnormal results from PFTs are more likely to have prolonged mechanical ventilation and postoperative pneumonia. No studies indicate a value of pulmonary function below which cardiac surgery is precluded. Fuster et al (2006) evaluated the effect of chronic lung diseases by correlating preoperative pulmonary function tests to postcardiac surgery outcome. Out of 1412 included in the study, an abnormal preoperative pulmonary function test was found in 39% of patients: obstructive in 26% (FEV1/FVC <0.7), restrictive in 9%, and combined obstructive-restrictive in 4%. In-hospital mortality was higher in patients with an abnormal test: 6.5% versus 0.9%. Mortality was clearly related with the severity of lung disease: 0.9% in patients with FEV1 of greater than 80%, 0.4% in patients with FEV1 of 60-80%, 10.8% in patients with FEV1 of 40-59%, and 54% in patients with FEV1 of less than 40%. COPD was not an independent predictor of mortality, but FEV1 of less than or equal to 60% was significantly associated with death (24.6% vs 1.4%). PREPARATION FOR SURGERYSection 7 of 11
Smoking cessation Instruct patients undergoing elective surgery to abstain from smoking for 8 weeks before surgery. Counseling, nicotine replacement therapies, bupropion (Zyban), and varenicline (Chantix) improve the quit rate and should be used aggressively. Recent data show that preoperative smoking abstinence of at least 4 weeks is necessary for patients who undergo pulmonary surgery to reduce the incidence of PPCs. However, in patients undergoing thoracotomy for primary or secondary lung tumors, there is no evidence of a paradoxical increase in pulmonary complications among those who quit smoking within 2 months of undergoing surgery. Smoking cessation can safely be encouraged prior to surgery. Chronic obstructive pulmonary disease Aggressively treat patients with COPD to achieve the best possible baseline function. Bronchodilators, smoking cessation, antibiotics, and chest physical therapy may help significantly reduce pulmonary complications. Treat patients who have a persistent wheeze, functional limitation, or severe air flow obstruction with perioperative steroids. Asthma Optimize asthma control prior to surgery. Perioperative systemic corticosteroids are recommended for persistent symptoms if the peak flow rate and FEV1 are less than 80% predicted or previous best. The safety of perioperative corticosteroid use is well established in patients with asthma. Perioperative steroids are not associated with death, serious infections, or adrenal suppression. Hypothalamic-pituitary-adrenal axis suppression should be assumed to be present in patients who have received systemic steroids for more than 3 weeks in the past 6 months. These patients should receive stress-dose coverage perioperatively (hydrocortisone 100 mg IV q8h). Preoperative antibiotics Indiscriminate use of prophylactic antibiotics does not lead to a reduction in pulmonary complications. These drugs may be used in patients with a clinically apparent respiratory infection. Cancel elective surgery if the patient has an active infection. Patient education Lung expansion, deep breathing and coughing, and incentive spirometry are best taught to the patient prior to surgery. For excellent patient education resources, visit eMedicine's Lung and Airway Center and Circulatory Problems Center. Also, see eMedicine's patient education articles Pulmonary Embolism, Bronchitis, Bacterial Pneumonia, Chronic Obstructive Pulmonary Disease (COPD), and Blood Clot in the Legs. Summary The following preoperative measures help minimize pulmonary complications in at-risk patients:
INTRAOPERATIVE STRATEGIESSection 8 of 11
Type of anesthesia The type of anesthesia and neuromuscular blockage affect the incidence of postoperative pulmonary complications. Intermediate- and shorter-acting agents (eg, vecuronium, rocuronium) are preferred because residual neuromuscular blockade from longer-acting agents may contribute to pulmonary complications. Based on available literature, spinal anesthesia may be safer than general anesthesia; therefore, spinal anesthesia should be considered for high-risk patients. Depending on the type and duration of surgery, endotracheal intubation and mechanical ventilation may be preferable because of the ability to monitor and control the respiratory rate and tidal volume. Type of neuromuscular blockade Pancuronium, a long-acting neuromuscular blocker, may lead to residual effects, cause hypoventilation, and increase complications. Use the intermediate-acting agents (eg, vecuronium, atracurium) in high-risk pulmonary patients. Duration and type of surgery When available, a less ambitious, shorter procedure should be considered in extremely high-risk patients. The duration of the surgical procedure is known to affect rate of postoperative complications. Because upper abdominal and thoracic operations carry the greatest risk, a percutaneous (laparoscopic) procedure should be substituted for an open procedure if possible. POSTOPERATIVE STRATEGIESSection 9 of 11
Lung expansion maneuvers Deep breathing exercises and incentive spirometry appear to be equally effective. These are components of chest physical therapy and have been shown to reduce postoperative pulmonary complications in high-risk patients. These maneuvers are greatly facilitated by regular visits with a physiotherapist. Although intermittent positive-pressure breathing was used commonly in the 1960s and 1970s, the postoperative complication rate with this is similar to that associated with deep breathing exercises. The cost and potential for abdominal distension makes the use of intermittent positive-pressure breathing unwarranted. CPAP therapy has been shown in the literature to be of benefit in a select group of patients as a secondary intervention for refractory atelectasis. When administered via a facemask, close patient supervision is required in case of vomiting or difficulty clearing secretions. Pain control Pain is a highly complex process involving specialized nociceptor fibers in the peripheral tissues; neurotransmitters and neuromodulators at all levels of neuraxis; integration of information in central nervous system; and learned behavior, affect, and cognitive status. Adequate postoperative pain control helps minimize pulmonary complications by encouraging earlier ambulation and performance of lung expansion maneuvers. Management of postoperative pain includes narcotics and narcoticlike medications administered peripherally into the epidural or intrathecal space. Intrathecal administration of narcotics is associated with a longer duration of analgesia (15-22 h), respiratory depression, and headaches. Intercostal nerve blocks have also been shown to be beneficial in upper abdominal surgery. Recent studies have popularized the use of epidural analgesia as an alternative to parenteral narcotics. In upper abdominal procedures, patients who received epidural analgesia had lower rates of pulmonary complications and a shorter duration of hospital stay. Epidural catheters can be used for patients undergoing thoracic or upper abdominal surgery by placing the catheter at the thoracic vertebral level. Epidural narcotics provide a longer duration of action, a lack of excessive sedation and respiratory depression, and a minimum of or no sensory motor loss. The addition of a local anesthetic provides a more rapid onset of action and may help localize correct catheter placement; however, hypotension and motor blockade are potential adverse effects. Epidural narcotics are morphine, fentanyl, sufentanil, and hydroxymorphine; the local anesthetics used for epidural analgesia are bupivacaine and ropivacaine. Adding small doses of local anesthetics to narcotics is a preferred approach. This potentiates pain relief, minimizes nerve blockade, and reduces adverse effects from both agents. Postoperative epidural analgesia and intercostal nerve blocks improve pain control and help reduce postoperative complications, with little risk. Cuschieri et al (1985) reported a postoperative pulmonary complication rate of 24% in postoperative patients receiving epidural analgesia, compared to a rate of 64% in those randomized to receive intramuscular morphine. Epidural hematoma is a rare complication, except when concomitant anticoagulation is prescribed. Epidural hematomas have been reported in patients receiving low molecular weight heparin (LMWH) who had epidural catheters. Warnings have been issued on this issue by the national advisory panels. A safe practice is to not place the epidural catheter for at least 12 hours after the last dose of LMWH. Perioperative use of nonsteroidal anti-inflammatory drugs may complement other pain management strategies. Nonsteroidal agents are known to decrease the narcotic requirement in the postoperative period. The newer agent ketorolac maybe administered intramuscularly as needed. Other nonsteroidal agents are given orally or rectally. Caution is advised in patients at risk for bleeding, with a history of peptic ulcer disease, and established renal dysfunction. Prevention of thromboembolism Prevention of deep venous thrombosis (DVT) and pulmonary embolism (PE) is important for all major surgeries but more so for hip or knee orthopedic procedures, in which the incidence rate may be as high as 50-60%. Risk is also high in elderly persons and in those patients with malignancies. Heparin prophylaxis (eg, a prophylactic strategy) can help significantly reduce the incidence of venous thrombosis, PE, and death in high-risk patients. Prevention of DVT in the lower extremities inevitably reduces the frequency of PE; therefore, populations at risk must be identified and safe and efficacious prophylactic modalities should be used. The risk groups identified in clinical practice and the prophylaxis recommended by the Sixth Consensus Conference on Antithrombotic Therapy is described in the following table: Prophylaxis Against Venous Thromboembolism
*Approximate risk without prophylaxis for all and/or proximal DVT or symptomatic PE Summary The following postoperative measures help minimize pulmonary complications in at-risk patients:
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REFERENCESSection 11 of 11
Perioperative Pulmonary Management excerpt Article Last Updated: Jun 30, 2006 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
