- Email: [email protected]
Postoperative Respiratory Failure
Thorac Surg Clin 16 (2006) 235–241
Postoperative Respiratory Failure John R. Roberts, MD, MBA The Surgical Clinic, The Sarah Cannon Cancer Center, 2400 Patterson Street, Suite 309, Nashville, TN 37203, USA
Postoperative respiratory failure is the most common perioperative cause of death after thoracic surgery in adult patients; however, ‘‘respiratory failure’’ is a broad descriptor and can include pneumonia, aspiration, adult respiratory distress syndrome (ARDS), and pulmonary emboli, among others. This general definition prevents understanding the causes of postoperative respiratory failure and limits actions that could decrease its incidence. When Medicare data are reviewed, the postoperative mortality rate after thoracic procedures ranges from 4% for a wedge resection to 12% for pneumonectomies to 18% for some esophageal procedures [1,2]. Recent data (2005) from the National Cancer Database are similar [2], as are collected data from a California registry [3] and a European registry [4]. The studies that have compared 30-day mortality with in-hospital mortality have found that in-hospital mortality is higher [5]; therefore, in-hospital mortality rather than 30-day mortality should be reported. Ginsberg and coworkers [6] analyzed perioperative mortality among the centers participating in the Lung Cancer Study Group in 1983. They found a perioperative mortality rate of 2.9% for lobectomy and a greater than 6% rate for pneumonectomy in these more experienced centers. A comparison of Ginsberg’s (1983) and Little’s (2005) data suggests that no improvement in perioperative mortality has occurred in 20 years. In contrast, the postoperative mortality rate for coronary artery bypass has decreased from around 6% at the institution of the Society of Thoracic Surgeons database to 1% to 2%. We can do better. The following analysis differentiates, rather than lumps, the different causes of postoperative E-mail address: [email protected]
respiratory failure. The discussion breaks down respiratory failure in thoracic patients into two distinct groups, aspiration and pneumonia, promoting actions to prevent respiratory failure. The goal is develop different strategies to avoid postoperative respiratory failure. In that way, the approach will be active (what can be done in the management of patients undergoing lung resection to prevent problems) rather than passive (what patient factors caused problems after surgery). Before that analysis, the operative risks after lung resections (lobectomies, pneumonectomies, elderly patients) and esophagectomies are reviewed to understand the data about operative risk. ‘‘Pure’’ respiratory failure Pure or primary respiratory failure (pneumonia, aspiration, and ARDS) is different from the other (secondary) types of respiratory failure in significant ways (Fig. 1). Many patients who are sick will require intubation even though they have no pulmonary illnesses. Most patients who are sick from sepsis, ketoacidosis, and renal failure may require intubation owing to an increased acid load. They require an increased minute ventilation to clear this increased acid load but otherwise have relatively normal respiratory function. If the causes remain untreated, these patients can develop pulmonary injury in the form of ARDS. Patients who have congestive heart failure (CHF) have normal pulmonary architecture with the superimposed fluid congestion due to depressed cardiac function. No intrinsic pulmonary injury is present, and correcting the cardiac function quickly corrects the pulmonary dysfunction.
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236
ROBERTS
Pain Postoperative Respiratory Failure
Pneumonia
Aspiration
Others (CHF, sepsis, renal failure, pulmonary emboli)
Fig. 1. Types of pure respiratory failure.
Prevention or prediction of respiratory failure A Medline search to identify articles on the prevention of postoperative respiratory failure yielded one citation [7]. This finding fits with the mind-set many of us were taught, that is, respiratory failure ‘‘just happens’’ after thoracic surgery and is difficult to prevent. A similar search on the prediction of postoperative respiratory failure/mortality yielded more than 200 articles. The literature has focused on identifying patients with enough respiratory reserve to recover from an episode of respiratory failure and not on ways to prevent pneumonia or aspiration. In fact, textbooks usually have chapters on the management of postoperative respiratory failure that do not include ways to prevent it. A primary error results from this approach. First, although an increased likelihood of postoperative mortality can be predicted by many different factors, most of the patients who die after thoracic surgery are not identified by preoperative factors [8]. Kohman and colleagues [9] described this problem accurately. Their study of 476 patients who underwent resection for lung cancer analyzed 37 preoperative risk factors and found that these factors accounted for only 12% of the operative mortality. Most of the operative mortality (60%) resulted from random or undefined factors. Focusing on preoperative factors does not help to identify factors to prevent respiratory failure; it only helps to identify those unlikely to recover from respiratory failure. Greater respiratory reserve is needed to recover from respiratory failure than to live an ordinary life. The exclusive focus herein is on patients who have primary respiratory failure, that is, pneumonia and aspiration. Separate causes of the two diseases and ways to prevent life-threatening complications are identified.
Many of the life-threatening complications in patients undergoing thoracic surgery result from poor pain management. Patients may have insufficient treatment for pain, fail to cough, and experience pneumonia from slow clearance of secretions. On the other hand, patients may be overtreated for pain, become too sedated, experience an ileus, fail to protect their airway during vomiting, and experience aspiration. Of course, this premise ignores all of the nonpulmonary causes of postoperative death, but they are relatively rare compared with the respiratory causes. The diagram in Fig. 2 describes a common clinical scenario. A patient complains of pain but may still be disoriented from anesthesia or narcotics received in the recovery room. Because of the pain or disorientation, the patient is treated with narcotics. The patient may then become disoriented and, at the same time, develop an ileus. The combination of drugs causes further sedation and can cause disorientation. The nurse then calls about an agitated patient and asks for sedation. The cycle can crank several times until the sedated patient vomits and aspirates. With this hypothesis, pain management becomes paramount in the treatment of patients undergoing thoracic surgery. Medicare data demonstrate that epidural use can decrease postoperative mortality [10]. Other data have suggested that minimally invasive surgery can decrease
Patient complains of pain
Patient becomes agitated due to disorientation
Patient receives sedatives or narcotics
Patient becomes disoriented, develops an ileus
Fig. 2. Clinical cycle of pain.
POSTOPERATIVE RESPIRATORY FAILURE
operative mortality because it decreases pain at the source. Secondarily, managing the gastrointestinal tract to prevent ileus and preventing oversedation will help to prevent aspiration. Alert patients can protect their airways during episodes of vomiting, whereas sedated patients cannot. Background ARDS or acute lung injury (ALI) is a wellknown factor in postoperative mortality after surgery of any type in adult patients [11]. Manuscripts on ARDS sometimes sound like ghost stories or vampire movies; they are dangerous, and you cannot see them coming or going [12]. Bayadi and coworkers [13] described ARDS in two patients who underwent limited wedge resection and could identify no cause; these patients almost surely aspirated. Many agents (bleomycin [14]) and processes (hypotension, blood transfusion, aspiration) are known to contribute to the likelihood of ARDS. Treatment is supportive only, with intubation, antibiotics, and management of secretions the mainstays. The use of steroids has been controversial but may be beneficial. Nitric oxide can be used to increase oxygenation immediately in patients failing standard treatment but has not been shown to increase survival [15]. Prediction of respiratory failure after lung resection Forced expiratory volume Numerous investigators have studied postoperative respiratory failure after lung resections to identify predictive factors. Some of the early work focused on the preoperative forced expiratory volume in 1 second (FEV1 or FEV1%) and found that patients with a low FEV1% had a greater risk of perioperative complications [16–20]. Ferguson and coworkers [21] compared the predictive value of FEV1% with diffusing capacity and found that diffusing capacity was more accurate. Pierce and colleagues [22] combined FEV1% and diffusing capacity to generate a parameter (predicted postoperative lung function) that would predict postoperative mortality. Diffusing capacity Ferguson has written most about the superiority of diffusing capacity over lung volumes to predict operative risk [21]. Patients with severe interstitial disease have the greatest loss of diffusing capacity, and these patients have been found to
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have a higher risk of respiratory failure and a poorer long-term survival when compared for stage [23]. Wang and coworkers [24] found that low diffusing capacity did predict perioperative mortality but did not predict long-term survival. Scoring systems Physiologic scoring systems focused on organs other than the lungs have been evaluated. Brunelli and coworkers [25,26] compared the POSSUM scoring system (Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity) with FEV1% in patients undergoing lung surgery. They found that the two systems gave an identical prediction of the risk of operative mortality. Pneumonectomy The high perioperative mortality after pneumonectomy (typically ranging from 6% to 12%) has led to increased scrutiny to factors that might predict a poor outcome. Patients undergoing pneumonectomy at M.D. Anderson had a perioperative mortality rate of 7% and a greater risk of death with a lower FEV1, right pneumonectomy, and extended resections [27]. Patel and coworkers [19] found that poor pulmonary function and smoking up to the time of surgery increased perioperative mortality. Patients undergoing pneumonectomy at Veterans’ Administration hospitals had a 30-day mortality rate of 11.5% that increased with dyspnea or poor nutritional status [28]. Alexiou and coworkers [29] found an operative mortality rate after pneumonectomy of 6.8% that increased in older patients and in those in whom a bronchopleural fistula developed. A Mayo Clinic series found an operative mortality rate of 7.0% and reported that preoperative chemotherapy, poor diffusing capacity, and right pneumonectomies were all associated with a higher risk [30]. A second study from the same institution found an operative mortality rate of 20.6% for completion pneumonectomies [31]. A University of Illinois study found an operative mortality rate of 10.5% [32], a European series found a 30-day mortality rate of 5.7% [20], and a Swiss study found an operative mortality of 9.3% [33], all in patients undergoing pneumonectomy. Martin and colleagues at Sloan-Kettering studied the impact of neoadjuvant chemotherapy on the risk of pneumonectomy [34]. They found an operative mortality rate of 11.6% for all patients undergoing pneumonectomy after
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ROBERTS
preoperative chemotherapy that increased to 23.6% for right pneumonectomies. Bernard and coworkers [30] also found that preoperative chemotherapy increased the risk of operative death after pneumonectomy. Not all studies have found pneumonectomy to be dangerous. A Chinese study emphasized limiting water-loading and reported no operative deaths [35].
Gibb [43] reported better results (operative mortality rate of 2.8%), although fewer than 50% of the patients presenting with esophageal cancer were considered healthy enough to undergo resection. Liedman and coworkers [44] found an increased risk with thoracoabdominal surgery when compared with laparatomy (12.5% versus 6.7%) and in patients whose maximum work capacity was less than 80 W.
Operative risk in older patients As operative techniques became safer, resection became more reasonable in elderly patients. In general, the risk is greater in elderly patients, although more recent studies suggest that it may be similar. Birim and coworkers [36] found an equivalent operative risk of 3.2% but a lower than expected medium-term survival in a comparison with younger patients. Roberts [37] found that thoracoscopic techniques eliminated the increased operative risk expected in elderly patients.
The importance of hospital (or surgeon) volume on complications
Exercise tolerance/oxygen consumption testing The use of exercise testing is intuitively satisfying. These modalities measure the function of the lungs and heart combined; however, as is true for FEV1% and diffusing capacity, exercise testing measures the ability of the system to recover from an insult, whether pneumonia or ARDS, and does not focus on the prevention of respiratory failure. Nonetheless, these tests have been popular. Miyoshi and coworkers [38] found no difference in FEV1% in patients who survived thoracotomy and those who died from thoracotomy; however, the two groups had markedly different oxygen consumption. Epstein and coworkers [39] found that patients who could not perform bicycle ergonometry had a mortality rate approaching 80%. Prediction of complications after esophagectomy Esophagectomy has always been a relatively dangerous procedure. Although patients undergoing esophagectomy may die from respiratory failure, they more often die from multi-system organ failure [40]. Nevertheless, some data suggest that respiratory failure contributes to postoperative mortality in esophagectomy patients. Tribble and coworkers [41] found that preoperative chest radiotherapy increased respiratory failure in patients undergoing esophagectomy. In the 1970s, limited 5-year survivals and high perioperative mortality were common. Conti and coworkers [42] described a 5-year survival rate of 4% and a 23% operative mortality. Ellis and
Esophagectomy was one of the first procedures found to have an increased risk in lower volume centers [45]. Several procedures are safer at high volume hospitals, including esophagectomy [46] and lobectomies and pneumonectomies [47]. Law and coworkers [48] found that increased surgical experience within their institution markedly decreased perioperative risk. The random nature of acute lung injury and adult respiratory distress syndrome It is well known that ARDS (previously called hyaline membrane disease) contributes to perioperative mortality after lung surgery [11]. As noted previously, Kohman demonstrated that most postoperative mortality after lung resections could not be predicted by analyzing preoperative factors. Others have found that the development of postoperative ALI/ARDS does not depend upon age, preoperative lung function, staging, and preoperative radiotherapy [49]. Ruffini further found that only 2.2% of a large cohort of lung resection patients experienced ARDS [49]. This finding illuminates a common problemd how to establish which patients will sustain pneumonia and which patients will sustain aspiration. Roberts and colleagues [50] chose to identify a subset of patients who experienced respiratory failure and grew no dominant organism in a group of patients who had aspirated.
Summary of literature about prediction of respiratory failure Lung volumes, diffusing capacity, and exercise oximetry can all be used to predict which patients will be more likely to have respiratory failure. Of these modalities, diffusing capacity may be the most accurate. Nevertheless, all of these factors are poor predictors in that most patients dying after thoracic surgery are not identified by these
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POSTOPERATIVE RESPIRATORY FAILURE
predictors. Most of the causes of death cannot be identified by preoperative or perioperative factors; therefore, we need to look for other factors (eg, aspiration) to understand these random risks.
Prevention Methods designed to prevent perioperative death should focus on respiratory failure (pneumonia, aspiration, and ARDS), cardiac disease, and pulmonary disease. Most physicians attempt to prevent pulmonary emboli with subcutaneous heparin and sequential devices and give perioperative antibiotics to prevent wound infection but do nothing to prevent respiratory failure and cardiac failure in patients undergoing lung surgery, except to refuse to do surgery. Although preventing cardiac failure is not addressed herein, many physicians treat pain in ways that diminish cardiac afterload and thus decrease the chance of cardiac failure (epidural placement). The prevention of respiratory failure has perhaps been made more difficult by the focus on pain as the fifth vital sign. Nurses are now trained to identify (and perhaps over identify) patients who feel pain and to urge additional narcotics as needed. Although in many cases this action is appropriate, in some patients it can lead to sedation, oversedation, ileus, vomiting, failure to protect the airway, and then aspiration. I propose that many patients who are otherwise stable after their resections experience pulmonary failure for no reason other than oversedation (usually from narcotics) that leads to vomiting when they are too sedated to protect their airway. Combining the evaluation of mental status and gastrointestinal tract management The author and his colleagues first proposed that gastrointestinal tract management is important to prevent respiratory failure in patients undergoing thoracotomy. In our study, two cohorts of patients were compareddone with nasogastric tubes placed after the induction of general anesthesia and one without the tubes (Fig. 3) [50]. A significant decrease in respiratory mortality occurred in the patients whose stomachs were kept empty overnight. Several members of the audience indicated that they managed the gastrointestinal tracts of their patients in similar fashions. Since this study, others have found evidence of tracheal aspiration during lateral positioning and have
Adequate Pain Management
Sedated
Not Sedated
GI tract management to prevent vomiting
GI tract management not necessary
Fig. 3. Pain management in sedated and nonsedated patients.
recommended nasogastric tubes during thoracotomy [51]. We have since modified our management somewhat and now place nasogastric tubes on induction and keep them in place until patients are completely awake. Those who remain sedated overnight have gastric drainage overnight, whereas those awaking early have their tubes removed (Fig. 3). With this strategy, we have been able to eliminate middle of the night episodes of acute hypoxia leading to intubation.
References [1] Whittle J, Steinberg EP, Anderson GF, et al. Use of Medicare claims data to evaluate outcomes in elderly patients undergoing lung resection for lung cancer. Chest 1991;100:729–34. [2] Little AG, Rusch VW, Bonner JA, et al. Patterns of surgical care of lung cancer patients. Ann Thorac Surg 2005;80(6):2051–6 [discussion: 2056]. [3] Romano PS, Mark DH. Patient and hospital characteristics related to in-hospital mortality after lung cancer resection. Chest 1992;101:1332–7. [4] Damhuis RA, Schutte PR. Resection rates and postoperative mortality in 7899 patients with lung cancer. Eur Respir J 1996;9:7–10. [5] Watanabe S, Asamura H, Suzuki K, et al. Recent results of postoperative mortality for surgical resections in lung cancer. Ann Thorac Surg 2004;78: 999–1002 [discussion: 1002–3]. [6] Ginsberg RJ, Hill LD, Eagan RT, et al. Modern thirty-day operative mortality for surgical resections in lung cancer. J Thorac Cardiovasc Surg 1983;86: 654–8. [7] Goodstein RS. Prevention of postoperative respiratory failure. J Am Osteopath Assoc 1980;79:406–8. [8] Canver CC, Chanda J. Intraoperative and postoperative risk factors for respiratory failure after coronary bypass. Ann Thorac Surg 2003;75:853–7 [discussion: 857–8]. [9] Kohman LJ, Meyer JA, Ikins PM, et al. Random versus predictable risks of mortality after
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thoracotomy for lung cancer. J Thorac Cardiovasc Surg 1986;91:551–4. Wu CL, Hurley RW, Anderson GF, et al. Effect of postoperative epidural analgesia on morbidity and mortality following surgery in Medicare patients. Reg Anesth Pain Med 2004;29:525–33 [discussion: 515–29]. Holland RH, Capers TH. Pulmonary hyaline membrane disease in adults: a cause of post-thoracotomy mortality. Am Rev Respir Dis 1961;84:719–24. Kanto WP Jr, Kuhns LP, Borer RC Jr, et al. Failure of serial chest radiographs to predict recovery from respiratory distress syndrome. Am J Obstet Gynecol 1978;131:757–60. el Bayadi S, Ettensohn DB, Yashar J. Adult respiratory distress syndrome after limited resection of adenocarcinoma of the lung. Thorax 1990;45:901–2. Goldiner PL, Carlon GC, Cvitkovic E, et al. Factors influencing postoperative morbidity and mortality in patients treated with bleomycin. BMJ 1978;1: 1664–7. Mathisen DJ, Kuo EY, Hahn C, et al. Inhaled nitric oxide for adult respiratory distress syndrome after pulmonary resection. Ann Thorac Surg 1998;66: 1894–902. Keagy BA, Lores ME, Starek PJ, et al. Elective pulmonary lobectomy: factors associated with morbidity and operative mortality. Ann Thorac Surg 1985; 40:349–52. Nakahara K, Ohno K, Hashimoto J, et al. Prediction of postoperative respiratory failure in patients undergoing lung resection for lung cancer. Ann Thorac Surg 1988;46:549–52. Markos J, Mullan BP, Hillman DR, et al. Preoperative assessment as a predictor of mortality and morbidity after lung resection. Am Rev Respir Dis 1989; 139:902–10. Patel RL, Townsend ER, Fountain SW. Elective pneumonectomy: factors associated with morbidity and operative mortality. Ann Thorac Surg 1992;54: 84–8. Myrdal G, Gustafsson G, Lambe M, et al. Outcome after lung cancer surgery: factors predicting early mortality and major morbidity. Eur J Cardiothorac Surg 2001;20:694–9. Ferguson MK, Little L, Rizzo L, et al. Diffusing capacity predicts morbidity and mortality after pulmonary resection. J Thorac Cardiovasc Surg 1988;96: 894–900. Pierce RJ, Copland JM, Sharpe K, et al. Preoperative risk evaluation for lung cancer resection: predicted postoperative product as a predictor of surgical mortality. Am J Respir Crit Care Med 1994;150:947–55. Chiyo M, Sekine Y, Iwata T, et al. Impact of interstitial lung disease on surgical morbidity and mortality for lung cancer: analyses of short-term and longterm outcomes. J Thorac Cardiovasc Surg 2003; 126:1141–6.
[24] Wang J, Olak J, Ferguson MK. Diffusing capacity predicts operative mortality but not long-term survival after resection for lung cancer. J Thorac Cardiovasc Surg 1999;117:581–6 [discussion: 586–7]. [25] Brunelli A, Fianchini A, Xiume F, et al. Evaluation of the POSSUM scoring system in lung surgery: Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity. Thorac Cardiovasc Surg 1998;46:141–6. [26] Brunelli A, Fianchini A, Gesuita R, et al. POSSUM scoring system as an instrument of audit in lung resection surgery: physiological and operative severity score for the enumeration of mortality and morbidity. Ann Thorac Surg 1999;67:329–31. [27] Wahi R, McMurtrey MJ, DeCaro LF, et al. Determinants of perioperative morbidity and mortality after pneumonectomy. Ann Thorac Surg 1989;48: 33–7. [28] Harpole DH Jr, DeCamp MM Jr, Daley J, et al. Prognostic models of thirty-day mortality and morbidity after major pulmonary resection. J Thorac Cardiovasc Surg 1999;117:969–79. [29] Alexiou C, Beggs D, Rogers ML, et al. Pneumonectomy for non-small cell lung cancer: predictors of operative mortality and survival. Eur J Cardiothorac Surg 2001;20:476–80. [30] Bernard A, Deschamps C, Allen MS, et al. Pneumonectomy for malignant disease: factors affecting early morbidity and mortality. J Thorac Cardiovasc Surg 2001;121:1076–82. [31] Miller DL, Deschamps C, Jenkins GD, et al. Completion pneumonectomy: factors affecting operative mortality and cardiopulmonary morbidity. Ann Thorac Surg 2002;74:876–83 [discussion: 883–4]. [32] Joo JB, DeBord JR, Montgomery CE, et al. Perioperative factors as predictors of operative mortality and morbidity in pneumonectomy. Am Surg 2001; 67:318–21 [discussion: 321–2]. [33] Licker M, Spiliopoulos A, Frey JG, et al. Risk factors for early mortality and major complications following pneumonectomy for non-small cell carcinoma of the lung. Chest 2002;121:1890–7. [34] Martin J, Ginsberg RJ, Abolhoda A, et al. Morbidity and mortality after neoadjuvant therapy for lung cancer: the risks of right pneumonectomy. Ann Thorac Surg 2001;72:1149–54. [35] Cui Y, Zhou D, Peng W, et al. Determinants of perioperative morbidity and mortality after pneumonectomy. Thorac Cardiovasc Surg 2004;52:45–8. [36] Birim O, Zuydendorp HM, Maat AP, et al. Lung resection for non-small-cell lung cancer in patients older than 70: mortality, morbidity, and late survival compared with the general population. Ann Thorac Surg 2003;76:1796–801. [37] Roberts JR. Thoracoscopic resection eliminates the increased operative risk normally seen in elderly patients treated for lung cancer. Proc Am Soc Clin Oncol 2005.
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[38] Miyoshi S, Nakahara K, Ohno K, et al. Exercise tolerance test in lung cancer patients: the relationship between exercise capacity and postthoracotomy hospital mortality. Ann Thorac Surg 1987;44:487–90. [39] Epstein SK, Faling LJ, Daly BD, et al. Inability to perform bicycle ergometry predicts increased morbidity and mortality after lung resection. Chest 1995;107:311–6. [40] Griffin S, Desai J, Charlton M, et al. Factors influencing mortality and morbidity following oesophageal resection. Eur J Cardiothorac Surg 1989;3: 419–23 [discussion: 424]. [41] Tribble CG, Flanagan TL, Christensen CP, et al. The influence of preoperative radiation therapy on morbidity and mortality for transhiatal esophagectomy. Am Surg 1991;57:716–9. [42] Conti S, West JP, Fitzpatrick HF. Mortality and morbidity after esophagogastrectomy for cancer of the esophagus and cardia. Am Surg 1977;43:92–6. [43] Ellis FH Jr, Gibb SP. Esophagogastrectomy for carcinoma: current hospital mortality and morbidity rates. Ann Surg 1979;190:699–705. [44] Liedman BL, Bennegard K, Olbe LC, et al. Predictors of postoperative morbidity and mortality after surgery for gastro-oesophageal carcinomas. Eur J Surg 1995;161:173–80. [45] Swisher SG, Deford L, Merriman KW, et al. Effect of operative volume on morbidity, mortality, and
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hospital use after esophagectomy for cancer. J Thorac Cardiovasc Surg 2000;119:1126–32. Metzger R, Bollschweiler E, Vallbohmer D, et al. High volume centers for esophagectomy: what is the number needed to achieve low postoperative mortality? Dis Esophagus 2004;17:310–4. Urbach DR, Bell CM, Austin PC. Differences in operative mortality between high- and low-volume hospitals in Ontario for 5 major surgical procedures: estimating the number of lives potentially saved through regionalization. CMAJ 2003;168:1409–14. Law S, Wong KH, Kwok KF, et al. Predictive factors for postoperative pulmonary complications and mortality after esophagectomy for cancer. Ann Surg 2004;240:791–800. Ruffini E, Parola A, Papalia E, et al. Frequency and mortality of acute lung injury and acute respiratory distress syndrome after pulmonary resection for bronchogenic carcinoma. Eur J Cardiothorac Surg 2001;20:30–6 [discussion: 36–7]. Roberts JR, Shyr Y, Christian KR, et al. Preemptive gastrointestinal tract management reduces aspiration and respiratory failure after thoracic operations. J Thorac Cardiovasc Surg 2000;119:449–52. Agnew NM, Kendall JB, Akrofi M, et al. Gastroesophageal reflux and tracheal aspiration in the thoracotomy position: should ranitidine premedication be routine? Anesth Analg 2002;95:1645–9.
Postoperative Respiratory Failure John R. Roberts, MD, MBA The Surgical Clinic, The Sarah Cannon Cancer Center, 2400 Patterson Street, Suite 309, Nashville, TN 37203, USA
Postoperative respiratory failure is the most common perioperative cause of death after thoracic surgery in adult patients; however, ‘‘respiratory failure’’ is a broad descriptor and can include pneumonia, aspiration, adult respiratory distress syndrome (ARDS), and pulmonary emboli, among others. This general definition prevents understanding the causes of postoperative respiratory failure and limits actions that could decrease its incidence. When Medicare data are reviewed, the postoperative mortality rate after thoracic procedures ranges from 4% for a wedge resection to 12% for pneumonectomies to 18% for some esophageal procedures [1,2]. Recent data (2005) from the National Cancer Database are similar [2], as are collected data from a California registry [3] and a European registry [4]. The studies that have compared 30-day mortality with in-hospital mortality have found that in-hospital mortality is higher [5]; therefore, in-hospital mortality rather than 30-day mortality should be reported. Ginsberg and coworkers [6] analyzed perioperative mortality among the centers participating in the Lung Cancer Study Group in 1983. They found a perioperative mortality rate of 2.9% for lobectomy and a greater than 6% rate for pneumonectomy in these more experienced centers. A comparison of Ginsberg’s (1983) and Little’s (2005) data suggests that no improvement in perioperative mortality has occurred in 20 years. In contrast, the postoperative mortality rate for coronary artery bypass has decreased from around 6% at the institution of the Society of Thoracic Surgeons database to 1% to 2%. We can do better. The following analysis differentiates, rather than lumps, the different causes of postoperative E-mail address: [email protected]
respiratory failure. The discussion breaks down respiratory failure in thoracic patients into two distinct groups, aspiration and pneumonia, promoting actions to prevent respiratory failure. The goal is develop different strategies to avoid postoperative respiratory failure. In that way, the approach will be active (what can be done in the management of patients undergoing lung resection to prevent problems) rather than passive (what patient factors caused problems after surgery). Before that analysis, the operative risks after lung resections (lobectomies, pneumonectomies, elderly patients) and esophagectomies are reviewed to understand the data about operative risk. ‘‘Pure’’ respiratory failure Pure or primary respiratory failure (pneumonia, aspiration, and ARDS) is different from the other (secondary) types of respiratory failure in significant ways (Fig. 1). Many patients who are sick will require intubation even though they have no pulmonary illnesses. Most patients who are sick from sepsis, ketoacidosis, and renal failure may require intubation owing to an increased acid load. They require an increased minute ventilation to clear this increased acid load but otherwise have relatively normal respiratory function. If the causes remain untreated, these patients can develop pulmonary injury in the form of ARDS. Patients who have congestive heart failure (CHF) have normal pulmonary architecture with the superimposed fluid congestion due to depressed cardiac function. No intrinsic pulmonary injury is present, and correcting the cardiac function quickly corrects the pulmonary dysfunction.
1547-4127/06/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.thorsurg.2006.05.002
thoracic.theclinics.com
236
ROBERTS
Pain Postoperative Respiratory Failure
Pneumonia
Aspiration
Others (CHF, sepsis, renal failure, pulmonary emboli)
Fig. 1. Types of pure respiratory failure.
Prevention or prediction of respiratory failure A Medline search to identify articles on the prevention of postoperative respiratory failure yielded one citation [7]. This finding fits with the mind-set many of us were taught, that is, respiratory failure ‘‘just happens’’ after thoracic surgery and is difficult to prevent. A similar search on the prediction of postoperative respiratory failure/mortality yielded more than 200 articles. The literature has focused on identifying patients with enough respiratory reserve to recover from an episode of respiratory failure and not on ways to prevent pneumonia or aspiration. In fact, textbooks usually have chapters on the management of postoperative respiratory failure that do not include ways to prevent it. A primary error results from this approach. First, although an increased likelihood of postoperative mortality can be predicted by many different factors, most of the patients who die after thoracic surgery are not identified by preoperative factors [8]. Kohman and colleagues [9] described this problem accurately. Their study of 476 patients who underwent resection for lung cancer analyzed 37 preoperative risk factors and found that these factors accounted for only 12% of the operative mortality. Most of the operative mortality (60%) resulted from random or undefined factors. Focusing on preoperative factors does not help to identify factors to prevent respiratory failure; it only helps to identify those unlikely to recover from respiratory failure. Greater respiratory reserve is needed to recover from respiratory failure than to live an ordinary life. The exclusive focus herein is on patients who have primary respiratory failure, that is, pneumonia and aspiration. Separate causes of the two diseases and ways to prevent life-threatening complications are identified.
Many of the life-threatening complications in patients undergoing thoracic surgery result from poor pain management. Patients may have insufficient treatment for pain, fail to cough, and experience pneumonia from slow clearance of secretions. On the other hand, patients may be overtreated for pain, become too sedated, experience an ileus, fail to protect their airway during vomiting, and experience aspiration. Of course, this premise ignores all of the nonpulmonary causes of postoperative death, but they are relatively rare compared with the respiratory causes. The diagram in Fig. 2 describes a common clinical scenario. A patient complains of pain but may still be disoriented from anesthesia or narcotics received in the recovery room. Because of the pain or disorientation, the patient is treated with narcotics. The patient may then become disoriented and, at the same time, develop an ileus. The combination of drugs causes further sedation and can cause disorientation. The nurse then calls about an agitated patient and asks for sedation. The cycle can crank several times until the sedated patient vomits and aspirates. With this hypothesis, pain management becomes paramount in the treatment of patients undergoing thoracic surgery. Medicare data demonstrate that epidural use can decrease postoperative mortality [10]. Other data have suggested that minimally invasive surgery can decrease
Patient complains of pain
Patient becomes agitated due to disorientation
Patient receives sedatives or narcotics
Patient becomes disoriented, develops an ileus
Fig. 2. Clinical cycle of pain.
POSTOPERATIVE RESPIRATORY FAILURE
operative mortality because it decreases pain at the source. Secondarily, managing the gastrointestinal tract to prevent ileus and preventing oversedation will help to prevent aspiration. Alert patients can protect their airways during episodes of vomiting, whereas sedated patients cannot. Background ARDS or acute lung injury (ALI) is a wellknown factor in postoperative mortality after surgery of any type in adult patients [11]. Manuscripts on ARDS sometimes sound like ghost stories or vampire movies; they are dangerous, and you cannot see them coming or going [12]. Bayadi and coworkers [13] described ARDS in two patients who underwent limited wedge resection and could identify no cause; these patients almost surely aspirated. Many agents (bleomycin [14]) and processes (hypotension, blood transfusion, aspiration) are known to contribute to the likelihood of ARDS. Treatment is supportive only, with intubation, antibiotics, and management of secretions the mainstays. The use of steroids has been controversial but may be beneficial. Nitric oxide can be used to increase oxygenation immediately in patients failing standard treatment but has not been shown to increase survival [15]. Prediction of respiratory failure after lung resection Forced expiratory volume Numerous investigators have studied postoperative respiratory failure after lung resections to identify predictive factors. Some of the early work focused on the preoperative forced expiratory volume in 1 second (FEV1 or FEV1%) and found that patients with a low FEV1% had a greater risk of perioperative complications [16–20]. Ferguson and coworkers [21] compared the predictive value of FEV1% with diffusing capacity and found that diffusing capacity was more accurate. Pierce and colleagues [22] combined FEV1% and diffusing capacity to generate a parameter (predicted postoperative lung function) that would predict postoperative mortality. Diffusing capacity Ferguson has written most about the superiority of diffusing capacity over lung volumes to predict operative risk [21]. Patients with severe interstitial disease have the greatest loss of diffusing capacity, and these patients have been found to
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have a higher risk of respiratory failure and a poorer long-term survival when compared for stage [23]. Wang and coworkers [24] found that low diffusing capacity did predict perioperative mortality but did not predict long-term survival. Scoring systems Physiologic scoring systems focused on organs other than the lungs have been evaluated. Brunelli and coworkers [25,26] compared the POSSUM scoring system (Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity) with FEV1% in patients undergoing lung surgery. They found that the two systems gave an identical prediction of the risk of operative mortality. Pneumonectomy The high perioperative mortality after pneumonectomy (typically ranging from 6% to 12%) has led to increased scrutiny to factors that might predict a poor outcome. Patients undergoing pneumonectomy at M.D. Anderson had a perioperative mortality rate of 7% and a greater risk of death with a lower FEV1, right pneumonectomy, and extended resections [27]. Patel and coworkers [19] found that poor pulmonary function and smoking up to the time of surgery increased perioperative mortality. Patients undergoing pneumonectomy at Veterans’ Administration hospitals had a 30-day mortality rate of 11.5% that increased with dyspnea or poor nutritional status [28]. Alexiou and coworkers [29] found an operative mortality rate after pneumonectomy of 6.8% that increased in older patients and in those in whom a bronchopleural fistula developed. A Mayo Clinic series found an operative mortality rate of 7.0% and reported that preoperative chemotherapy, poor diffusing capacity, and right pneumonectomies were all associated with a higher risk [30]. A second study from the same institution found an operative mortality rate of 20.6% for completion pneumonectomies [31]. A University of Illinois study found an operative mortality rate of 10.5% [32], a European series found a 30-day mortality rate of 5.7% [20], and a Swiss study found an operative mortality of 9.3% [33], all in patients undergoing pneumonectomy. Martin and colleagues at Sloan-Kettering studied the impact of neoadjuvant chemotherapy on the risk of pneumonectomy [34]. They found an operative mortality rate of 11.6% for all patients undergoing pneumonectomy after
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preoperative chemotherapy that increased to 23.6% for right pneumonectomies. Bernard and coworkers [30] also found that preoperative chemotherapy increased the risk of operative death after pneumonectomy. Not all studies have found pneumonectomy to be dangerous. A Chinese study emphasized limiting water-loading and reported no operative deaths [35].
Gibb [43] reported better results (operative mortality rate of 2.8%), although fewer than 50% of the patients presenting with esophageal cancer were considered healthy enough to undergo resection. Liedman and coworkers [44] found an increased risk with thoracoabdominal surgery when compared with laparatomy (12.5% versus 6.7%) and in patients whose maximum work capacity was less than 80 W.
Operative risk in older patients As operative techniques became safer, resection became more reasonable in elderly patients. In general, the risk is greater in elderly patients, although more recent studies suggest that it may be similar. Birim and coworkers [36] found an equivalent operative risk of 3.2% but a lower than expected medium-term survival in a comparison with younger patients. Roberts [37] found that thoracoscopic techniques eliminated the increased operative risk expected in elderly patients.
The importance of hospital (or surgeon) volume on complications
Exercise tolerance/oxygen consumption testing The use of exercise testing is intuitively satisfying. These modalities measure the function of the lungs and heart combined; however, as is true for FEV1% and diffusing capacity, exercise testing measures the ability of the system to recover from an insult, whether pneumonia or ARDS, and does not focus on the prevention of respiratory failure. Nonetheless, these tests have been popular. Miyoshi and coworkers [38] found no difference in FEV1% in patients who survived thoracotomy and those who died from thoracotomy; however, the two groups had markedly different oxygen consumption. Epstein and coworkers [39] found that patients who could not perform bicycle ergonometry had a mortality rate approaching 80%. Prediction of complications after esophagectomy Esophagectomy has always been a relatively dangerous procedure. Although patients undergoing esophagectomy may die from respiratory failure, they more often die from multi-system organ failure [40]. Nevertheless, some data suggest that respiratory failure contributes to postoperative mortality in esophagectomy patients. Tribble and coworkers [41] found that preoperative chest radiotherapy increased respiratory failure in patients undergoing esophagectomy. In the 1970s, limited 5-year survivals and high perioperative mortality were common. Conti and coworkers [42] described a 5-year survival rate of 4% and a 23% operative mortality. Ellis and
Esophagectomy was one of the first procedures found to have an increased risk in lower volume centers [45]. Several procedures are safer at high volume hospitals, including esophagectomy [46] and lobectomies and pneumonectomies [47]. Law and coworkers [48] found that increased surgical experience within their institution markedly decreased perioperative risk. The random nature of acute lung injury and adult respiratory distress syndrome It is well known that ARDS (previously called hyaline membrane disease) contributes to perioperative mortality after lung surgery [11]. As noted previously, Kohman demonstrated that most postoperative mortality after lung resections could not be predicted by analyzing preoperative factors. Others have found that the development of postoperative ALI/ARDS does not depend upon age, preoperative lung function, staging, and preoperative radiotherapy [49]. Ruffini further found that only 2.2% of a large cohort of lung resection patients experienced ARDS [49]. This finding illuminates a common problemd how to establish which patients will sustain pneumonia and which patients will sustain aspiration. Roberts and colleagues [50] chose to identify a subset of patients who experienced respiratory failure and grew no dominant organism in a group of patients who had aspirated.
Summary of literature about prediction of respiratory failure Lung volumes, diffusing capacity, and exercise oximetry can all be used to predict which patients will be more likely to have respiratory failure. Of these modalities, diffusing capacity may be the most accurate. Nevertheless, all of these factors are poor predictors in that most patients dying after thoracic surgery are not identified by these
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predictors. Most of the causes of death cannot be identified by preoperative or perioperative factors; therefore, we need to look for other factors (eg, aspiration) to understand these random risks.
Prevention Methods designed to prevent perioperative death should focus on respiratory failure (pneumonia, aspiration, and ARDS), cardiac disease, and pulmonary disease. Most physicians attempt to prevent pulmonary emboli with subcutaneous heparin and sequential devices and give perioperative antibiotics to prevent wound infection but do nothing to prevent respiratory failure and cardiac failure in patients undergoing lung surgery, except to refuse to do surgery. Although preventing cardiac failure is not addressed herein, many physicians treat pain in ways that diminish cardiac afterload and thus decrease the chance of cardiac failure (epidural placement). The prevention of respiratory failure has perhaps been made more difficult by the focus on pain as the fifth vital sign. Nurses are now trained to identify (and perhaps over identify) patients who feel pain and to urge additional narcotics as needed. Although in many cases this action is appropriate, in some patients it can lead to sedation, oversedation, ileus, vomiting, failure to protect the airway, and then aspiration. I propose that many patients who are otherwise stable after their resections experience pulmonary failure for no reason other than oversedation (usually from narcotics) that leads to vomiting when they are too sedated to protect their airway. Combining the evaluation of mental status and gastrointestinal tract management The author and his colleagues first proposed that gastrointestinal tract management is important to prevent respiratory failure in patients undergoing thoracotomy. In our study, two cohorts of patients were compareddone with nasogastric tubes placed after the induction of general anesthesia and one without the tubes (Fig. 3) [50]. A significant decrease in respiratory mortality occurred in the patients whose stomachs were kept empty overnight. Several members of the audience indicated that they managed the gastrointestinal tracts of their patients in similar fashions. Since this study, others have found evidence of tracheal aspiration during lateral positioning and have
Adequate Pain Management
Sedated
Not Sedated
GI tract management to prevent vomiting
GI tract management not necessary
Fig. 3. Pain management in sedated and nonsedated patients.
recommended nasogastric tubes during thoracotomy [51]. We have since modified our management somewhat and now place nasogastric tubes on induction and keep them in place until patients are completely awake. Those who remain sedated overnight have gastric drainage overnight, whereas those awaking early have their tubes removed (Fig. 3). With this strategy, we have been able to eliminate middle of the night episodes of acute hypoxia leading to intubation.
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