Abstract
Postoperative pulmonary complications (PPCs) represent some of the most common, morbid, deadly, and costly surgical complications. This chapter details the latest knowledge regarding risk factors for PPC. As well as providing tools for identifying high-risk patients, a discussion of procedure details is also provided. Strategies for preoperative and postoperative patient management are also reviewed. Urologists should identify and inform patients who smoke of the associated risk factors for pulmonary complications as well as for urothelial cancer. The chapter provides extensive discussion regarding specific complications including atelectasis, pneumothorax, and pulmonary embolism. A review of more recent information regarding the risks of obstructive sleep apnea and novel risk stratification tools are also detailed. Additionally, the chapter examines specific approaches to common urologic procedures and their associated pulmonary risks including percutaneous nephrolithotomy and laparoscopic urologic surgery. Strategies for prevention and management of these complications are provided.
Keywords
Postoperative pulmonary complications, Pneumothorax, Hydrothorax, Atelectasis, Percutaneous nephrolithotomy, Laparoscopic surgery, Chylothorax, Pleural effusion, Pneumonia
Chapter Outline
Preoperative Pulmonary Assessment
Postoperative Management for Patients With Obstructive Sleep Apnea
Complications Involving the Pleural Space
Pulmonary Complications of Open and Laparoscopic Urologic Surgery
Pulmonary Complications of Percutaneous Nephrolithotomy
Patients With Prior Bleomycin Chemotherapy
[CR]
Key Points
- 1.
Accurate preoperative identification of patients at risk for developing postoperative pulmonary complications optimizes preoperative testing and ideally minimizes occurrence of postoperative complications.
- 2.
Risk factors for respiratory complications stem from patient-related factors as well as from procedure-related factors including surgical site, duration of surgery, and type of anesthesia. Procedure-related factors carry the highest risk for postoperative pulmonary complications.
- 3.
Urologists should identify and inform patients who smoke of the associated risk factors for pulmonary complications as well as for urothelial cancer. Cigarette smoking cessation should be 4 weeks or more prior to surgery to begin to provide benefit.
- 4.
Multiple new preoperative risk calculators are available to assist in assessing risk stratification. The most important patient-related risk factor is age, increasing significantly over the age of 50.
- 5.
Recommendations for patients undergoing major urologic procedures include intermittent pneumatic compression, use of graduated compression stockings, early and frequent ambulation, in addition to pharmacologic venous thromboembolism (VTE) prophylaxis when possible.
Multiple studies evaluating complications following noncardiac surgery demonstrate that postoperative pulmonary complications (PPCs) occur at similar frequency and result in similar rates of morbidity and mortality as cardiovascular complications. The reported rates of PPCs range from 5% to 40%, dependent upon procedure risk, with PPC-associated mortality risks ranging from 10% to 25%. Data from the National Surgical Quality Improvement Program (NSQIP) demonstrate that PPCs are the most costly of postoperative complications and result in the longest hospital length of stay.
Although there is no exact definition of what constitutes a PPC, most literature includes conditions such as atelectasis, infection (pneumonia, bronchitis), respiratory failure requiring prolonged mechanic respiratory support, acute respiratory distress syndrome (ARDS), and hypoxemia. For the purposes of this chapter, we have also included discussion regarding pulmonary embolism and additional surgical complications such as pneumothorax. The economic impact of PPCs has been estimated to account for 3.4 billion dollars in health care costs in the United States. Ultimately, prevention of PPC requires careful assessment of risk factors, both from patient characteristics and procedure-associated factors. Proper identification of these risk factors aids development of strategies to prevent these complications.
Preoperative Pulmonary Assessment
Identifying the primary risk factors associated with PPCs assists with accurate risk stratification prior to surgery and informs strategies to reduce morbidity and mortality. Pulmonary risks factors stem from two sources, preexisting patient characteristics as well as procedure-associated factors.
Patient Factors
Identifying factors that predispose to the development of PPC requires an understanding of the principal patient-related risk factors as well as an understanding of the degree of risk associated with these factors. The American College of Physicians (ACP) provides guidelines for assessing PPC risk factors for noncardiopulmonary surgery. These guidelines stem from a systematic review of the existing literature performed by Smetana and colleagues. This work, published in 2006, remains the largest evidence-based source of information regarding PPC. From these data, the primary patient-related factors associated with increased risk of PPCs and are detailed in Table 2.1 .
| Risk Factor | Odds Ratio for PPC | 95% Confidence Interval |
|---|---|---|
| Age | ||
| 50–59 | 1.50 | 1.31–1.71 |
| 60–69 | 2.09 | 1.65–2.64 |
| 70–79 | 3.04 | 2.11–4.39 |
| ≥ 80 | 5.63 | 4.63–6.85 |
| ASA Score ≥2 | 4.87 | 3.34–7.10 |
| Congestive heart failure | 2.93 | 1.02–8.03 |
| Total functional dependence | 2.51 | 1.99–3.15 |
| COPD | 2.36 | 1.90–2.93 |
| Cigarette use | 1.40 | 1.17–1.69 |
The most important patient-related risk factors found by this review are patient age and presence of an increased American Society of Anesthesiologist’s (ASA) score. Age confers an increasing level of risk for PPC for each decade over 50. Ultimately, as age increases beyond 80, the odds ratio increases to 5.63 as compared to patients younger than 50. Given that the population requiring major urologic surgery is often in this age range, this risk factor becomes especially pertinent to consider during urologic preoperative evaluation.
The existence of chronic lung diseases such as chronic obstructive pulmonary disease (COPD) warrants special consideration when assessing PPC risk. In fact, the presence of chronic lung disease represents the most common risk factor identified by Smetana and colleagues. However, the degree of this risk factor varies widely upon the degree of pulmonary impairment. Consequently, the presence of preoperative congestive heart failure (CHF) confers a higher risk for PPC than COPD (OR 2.93 vs 2.36, respectively).
Additional significant risk factors for PPC include active cigarette use and decreased overall functional dependence. More recently, data regarding obstructive sleep apnea (OSA) indicate that OSA confers an increased risk for immediate airway management complications as well as for PPC. Patients should thus be screened for signs and symptoms of OSA prior to undergoing anesthesia. Several tools for assessing for OSA have been published and assist with assessing level of OSA risk.
Interestingly, this systematic review did not find strong evidence demonstrating an increased risk of pulmonary complications amongst patients with obesity and controlled asthma, findings corroborated by additional studies. However, obesity remains a risk factor for development of venous thromboembolic complications including pulmonary embolism and thus remains an important patient factor clinicians should consider when assessing risk.
While the ACP guideline provides a necessary evidence-based framework for assessing risk for PPC, the data have not been systematically updated for nearly 10 years. More recent data indicate that additional risk factors include respiratory infections within 1 month prior to surgery, diabetes, preoperative hypoxemia, and preoperative anemia. Currently, prospective studies are under way to improve PPC definition and identify more accurate risk factors.
Given that most patients requiring urologic intervention are over the age of 50, and many patients undergoing procedures associated with urothelial carcinoma have a history of significant tobacco use, the risk of PPC in this patient cohort warrants special attention. Prior exposure to bleomycin presents an additional urologic-specific patient risk factor that will be discussed in more detail later in the chapter.
Cigarette Smoking
When considering patient-related factors, cigarette smoking warrants additional commentary. Smoking tobacco is a well-known risk factor for cardiac, vascular, infectious, and respiratory complications. Many PPCs occur at a higher rate in smokers, conferring an increased risk with an odds ratio of 1.4 to 4.3. Tobacco smoking confers additional risk for urologic malignancies, increasing the risk of renal cell carcinoma and urothelial carcinoma, and continued tobacco use is associated with disease progression and recurrence.
In their prospective study of 200 patients undergoing coronary artery bypass surgery, Warner and associates demonstrated that patients who had stopped smoking ≥8 weeks preoperatively had a significantly lower risk of pulmonary complications than did patients who were active smokers (14.5% vs 33%). Moreover, patients who had stopped smoking for >6 months had pulmonary complication rates similar to those patients who had never smoked (11.1% vs 11.9%). Surprisingly, patients who had quit smoking <8 weeks preoperatively experienced more untoward pulmonary events than did active smokers (57% vs 33%). This appears to be due to increased airway reactivity and sputum production that occur in the initial period after smoking cessation. Recent studies have corroborated these findings, indicating that smoking cessation ultimately benefits patients but requires 4 to 6 weeks to provide benefit.
Given the important role cigarette smoking plays both in the pathophysiology of urologic malignancies and on the risk of PPC as well as other major postoperative complications, the urologist is in a unique position to intervene and provide guidance on smoking cessation. In addition, observational studies indicate that patients may be more receptive to quitting during the perioperative period. A recent prospective study within a urology clinic demonstrated the efficacy of this approach.
Patients who smoke should be identified preoperatively. The duration and amount of smoking should be quantified. These patients should be informed that smoking increases the perioperative risk and also that quitting can decrease this risk. Preoperative abstinence should be recommended for a minimum period of 4–6 weeks prior to surgery.
Procedure Factors
Procedure-related factors associated with risks for PPC are displayed in Table 2.2 and are adapted from the ACP guideline. In terms of risk assessment, procedure relegated factors represent the most significant predictors for development of PPC.
| Risk Factor | Odds Ratio for PPC | 95% Confidence Interval |
|---|---|---|
| Surgical site | ||
| Aortic | 6.90 | 2.74–17.3 |
| Thoracic | 4.24 | 2.89–6.23 |
| Any abdominal | 3.01 | 2.43–3.72 |
| Upper abdominal | 2.91 | 2.35–3.60 |
| Emergency surgery | 2.21 | 1.57–3.11 |
| Surgery >3 hours | 2.26 | 1.47–3.47 |
Surgical Approach and Anatomic Considerations
Special consideration should be paid toward surgical anatomic location. While certain surgical sites (aortic, thoracic, neurologic) are not common in urologic procedures, it is important to note that abdominal surgical location confers an odds ratio of 3.01 and thus is a critical factor to be considered as risk factor for PPC. Regardless of proximity to the diaphragm, surgical trauma to the abdomen impacts respiratory function. Abdominal incisions decrease lung volumes in a restrictive pattern, resulting in reduction in vital capacity of 50–60% and functional residual capacity by approximately 30%. Incisional pain limits respiratory motion, often subconsciously, promoting development of atelectasis and pleural effusions. Manipulation of the intestines during transperitoneal dissection can result in phrenic nerve stimulation, which further impairs normal respiratory function.
Urologic procedures that involve, or are in close proximity to, the diaphragm represent a high-risk group. This category includes surgical approaches utilizing flank, subcostal, and thoraco-abdominal incisions. Additionally, minimally invasive renal surgery, upper retroperitoneal dissection, and percutaneous renal access present anatomic risk to the pulmonary space. Proximity to the diaphragm and pleural cavity may result in both obvious and discrete injury to the diaphragm and entry into pleural space. While these injuries are often recognized and managed intraoperatively, opportunity for occult injury should still be considered and postoperative assessment should address this risk.
Additional procedure-related factors include prolonged surgical time (>3 hours) and emergent procedures.
Anesthesia
Evidence also supports that general anesthesia represents an independent risk factor for PPC. Induction of general anesthesia results in an immediate development of atelectasis due to collapse of lung tissue, ventilation-perfusion mismatch, creation of respiratory dead-space, hypoxemia, and decreased surfactant function. Narcotics, sedatives, and other centrally acting drugs may depress respiratory drive and further increase risk for PPC.
Preoperative Patient Evaluation
The evaluation of preoperative pulmonary risk begins with a detailed history and physical examination. Patients with a smoking history should be identified and efforts included to quantify duration and amount of smoking. A history of chronic lung disease should also be identified. A recent history of an upper respiratory infection, including influenza, should also be identified. A thorough pulmonary evaluation such as exercise intolerance, chronic cough, sputum production, previous pulmonary surgery, previous chemotherapy (see later), dyspnea at rest or on exertion, wheezing, rales, cyanosis, or weakness or debilitation assist in identifying patients at risk. Evaluation for signs of sleep apnea may also help with risk stratification.
A chest radiograph should be obtained in all patients with any of the above risk factors or over the age of 50. However, clear evidence supporting a benefit from obtaining routine chest radiographs does not currently exist.
Evidence indicates that preoperative pulmonary function testing (PFT) does not accurately predict PPC, and consequently these tests are overused. Debate continues regarding the value of PFT. The ACP systematic review concluded that PFT is reasonable for patients with COPD or asthma in whom clinical evaluation is unclear and in patients with unexplained dyspnea or exercise intolerance.
As preoperative hypoalbuminemia predicts PPC, recognition of patients with severe malnourishment should be identified, and it is reasonable to recommend preoperative nutritional supplementation.
Several risk calculators have been developed to provide quantitative assessment for pulmonary risk and are available online. One example is the ARISCAT risk score, which was developed and validated from European surgical databases and uses five risk factors to predict risk of PPC. This is shown in Table 2.1 . Implementation of these risk calculators offers numerical risk evaluations that may assist with clinical decision making.
Preoperative Strategies
Once a patient is identified as having a higher risk for PPC, several strategies may be employed to decrease that risk. As stated above, urologists should instruct and guide current smokers to stop smoking and provide tools and referrals for patients that are willing to attempt cessation.
Patients with chronic lung disease who do not appear to be in optimal status should have surgery deferred until their pulmonary status has been medically optimized. Patients with a history of asthma should also be assessed for how well their asthma is controlled. At the time of surgery these patients should be free of wheezing and should use beta-agonist inhalers prior to intubation and during the perioperative period. Any signs of a recent upper respiratory infection, even for patients without a history of lung impairment, should prompt further workup and delay in surgical timing until recovery from respiratory infection is complete.
Preoperative pulmonary physical therapy has been shown to reduce postoperative atelectasis and hospital stay in patients undergoing cardiac surgery. Preoperative teaching with incentive spirometry for all patients undergoing elective abdominal surgery results in improved understanding of the techniques and perioperative use. It is our practice to provide this teaching and to reinforce incentive spirometry in the perioperative period.
Postoperative Strategies
The strategy for postoperative pulmonary rehabilitation differs from preoperative approaches in that postoperative tactics apply to every patient, regardless of preoperative risk level. These strategies focus on maneuvers aimed to counteract the surgical and anesthesia impairments on respiratory function. Adequate pain control and lung expansion through incentive spirometry (IS), coughing, and early ambulation comprise the cornerstone of such strategies.
Incentive Spirometry and Deep Breathing Exercises
While a few small trials demonstrate that utilizing postoperative IS and deep breathing exercises (DBE) reduces PPC and length of stay, a recent Cochrane review found no evidence that IS prevented PPC. The authors concluded that the evidence for this conclusion is of low quality and that higher quality trials are needed to evaluate the efficacy of IS.
It remains our practice to employ incentive spirometry in both the immediate postoperative and perioperative period.
Early Mobilization
Facilitating early ambulation improves fluid mobilization and increases respiratory utilization. While very few studies provide guidance on the impact of mobilization, one study demonstrated an increase in PPC for each additional day of delay in mobilization following abdominal surgery. It remains our practice to encourage ambulation and routinely employ the assistance of physical therapists for patients that require assistance.
Pain Control
Adequate pain control ameliorates the pulmonary functional depression induced by surgical incisions and assists with early ambulation. However, use of opioid efficacy is limited by subsequent depression of the respiratory drive. Epidural anesthesia has been associated with fewer PPCs, including in patients with COPD undergoing abdominal surgery. Intercostal nerve blockade may also help reduce PPC in patients undergoing subcostal or upper abdominal incisions. For patients with risk factors for PPC, consideration of epidural anesthesia or intercostal nerve block should be considered when applicable.
Nasogastric Tube
Routine use of postoperative nasogastric tube (NGT) increases PPC including pneumonia and atelectasis, although on Cochrane review this trend was insignificant (p = 0.07). We do not recommend routine postoperative NGT and employ this only in situations when worsening postoperative nausea, distention, or bilious vomiting develop due to postoperative ileus.
Bronchospasm
Bronchospasm in the postoperative setting may occur due to histamine release from perioperative medications, aspiration, and exacerbation of underlying pulmonary disease such as asthma or COPD. Management rests upon the identification of an underlying cause and treating it appropriately. Removal of offending drugs or allergens and addressing asthma or COPD with inhaled bronchodilators represent first-line strategies. For refractory cases, consider employing systemic steroids.
Atelectasis
Atelectasis commonly occurs following abdominal surgery, affecting patients in all ranges. A consequence of surgical and anesthetic effects, atelectasis develops when dependent airways collapse, ultimately leading to changes in the compliance of lung tissue, decreased ventilation in these regions, and reduced movement of airway secretions. These changes result in decreased oxygen exchange and increase respiratory effort and hypoxemia. In younger healthy patients, these changes may result in little to no clinical effect but may significantly alter the clinical course for patients with impaired lung function or comorbidities such as CHF.
Atelectasis develops in the early postoperative course with symptoms of hypoxemia typically becoming apparent approximately 48–60 hours following surgery and continuing for several days. Hypoxemia that develops earlier than this time course (i.e., in the postanesthesia recovery unit) should prompt urgent investigation into alternative PPC including pneumothorax, upper airway edema, and anesthesia effects. Atelectasis in the postoperative setting is most commonly nonobstructive in nature and typically results from loss of contact between the parietal and visceral pleurae or compression of the lower and middle lobes, often due to pleural effusion.
Within the appropriate clinical time course, atelectasis should be suspected when findings such as tachypnea, dyspnea, and hypoxemia are noted. Patients should be assessed for abundant sputum production and secretions, evident as rhonchi on auscultation or frequent productive cough. Obtaining a chest radiograph or chest computed tomography (CT) often confirms the diagnosis.
Management of atelectasis through methods to reverse the process of lung volume collapse can prevent further PPC. Strategies for managing atelectasis differ depending upon the level of airway secretions. For those without abundant secretions, implementation of supplemental oxygen, DBE, and IS remains the mainstay of initial management. Patients without secretions that remain hypoxic and with continued increased respiratory effort may benefit from positive airway pressure (CPAP). Squadrone et al. reported results of a randomized multicenter controlled trial of CPAP versus supplemental oxygen alone and demonstrated a decrease in intubation, pneumonia, and sepsis for patients receiving CPAP. For patients with significant secretions, frequent chest physiotherapy and suctioning (nasogastric if the patient is not able to expectorate) should be implemented. In patients who fail to improve with these methods, consider pulmonary consultation for consideration of possible bronchoscopy and other techniques aimed to improve secretion clearance.
Pleural Effusion
Limited data suggest that pleural effusion detected on chest radiograph occurs in up to 49% of patients’ surgery when evaluated between 48 to 72 hours following abdominal surgery. Pleural effusion appears to occur more commonly following upper abdominal surgery. Management of effusion is primarily conservative, as most of effusions resolve spontaneously. Pulmonary toilet with DBE and IS as well as early and frequent ambulation may serve to hasten resolution.
In the setting of persistent effusion or clinical concern, diagnostic evaluation of an effusion requires thoracentesis. Thoracentesis can be performed at the bedside, and analysis can help establish diagnoses including malignancy, empyema, chylothorax, urinothorax, hemothorax, and infection.
Postoperative Pneumonia
The incidence of postoperative pneumonia ranges from 1.5% to 50%, depending on a wide array of conditions including type of anesthesia, surgical details, and patient risk factors. Postoperative pneumonia can present similarly to other conditions, such as atelectasis, pulmonary edema, and pulmonary embolism. However, postoperative pneumonia requires accurate diagnosis as it is associated with mortality rates from 1.5% to 10%.
Postoperative pneumonia should be considered in patients with fevers, increased white blood cell count, and chest imaging demonstrating new onset pulmonary infiltrates. Clinical symptoms of fever, tachypnea, dyspnea, and hypoxemia typically develop within the first five postoperative days. Risk factors such as COPD, altered lung defenses, and active smoking should increase clinical suspicion.
Successful management of postoperative pneumonia requires accurate pathogen identification and appropriate antibiotics. These infections, primarily nosocomial in origin, frequently result from resistant organisms, although multiple organisms may be identified. One study demonstrated that the most common pathogens were gram-negative bacteria (e.g., Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter species), Staphylococcus aureus, and Streptococcus pneumoniae. Prolonged intubation and exposure to antibiotics as well as COPD may increase risk for pneumonia due to organisms such as Pseudomonas aeruginosa, Acinetobacter, or methicillin-resistant S. aureus (MRSA). Postoperative treatment requires accurate collection of respiratory culture and prompt empiric antibiotics.
Aspiration pneumonia during the postoperative period may result in patients with risk factors for decreased protection of their airways. These include neurologic disorders, impaired cough reflex, impaired mental status following surgery leading to dysfunctional swallowing, and postoperative vomiting. Introduction of gastric fluids or particulate matter into the lower airways may stimulate an inflammatory response and subsequent chemical pneumonitis, bacterial infection, or mechanical obstruction.
Chemical pneumonitis occurs quickly after aspiration of gastric contents and may lead to dyspnea and respiratory distress. Clinical symptoms include abrupt dyspnea, cyanosis, severe hypoxemia, and infiltrates on chest imaging. The inflammatory response may rapidly progress to acute respiratory distress syndrome (ARDS) and lead to respiratory failure. As ARDS develops, inflammation of the lung parenchyma results in systemic release of inflammatory mediators and frequently results in multisystem organ failure. Treatment of ARDS involves mechanical ventilation, treatment of underlying causes, supportive care, and antibiotic coverage if indicated.
Gupta and colleagues have developed and validated a risk calculator for predicting postoperative pneumonia. This tool is available for free download at surgicalriskcalculator.com .
Postoperative Management for Patients With Obstructive Sleep Apnea
More than half of patients with clinically important obstructive sleep apnea (OSA) present for surgery without formal diagnosis of OSA. As the prevalence of obesity continues to rise, the rates of undiagnosed OSA in surgical patients will likely continue to increase. As a result of the large number of patients that are undiagnosed, heightened vigilance for postoperative complications in patients with risk factors for OSA, such as obesity, should be considered.
Hypoventilation, periods of central apnea and upper airway obstruction combine to lead to rapid hypoxemia for patients with OSA. Consequently, careful monitoring of blood oxygen saturation both in the postanesthesia recovery unit, and also during postoperative hospital stays, is prudent. Patients who use CPAP at home should resume as soon as possible following surgery. The evidence does not demonstrate a clear benefit for initiating CPAP in patients with OSA who have not used this preoperatively unless these patients are at high risk for PPC. For patients demonstrating hypoxemia or hypoventilation following surgery, implementation of CPAP should be considered on an individual basis.
Complications Involving the Pleural Space
Injury involving the pleural cavity can occur during abdominal surgery, although risk is highest during surgery in the upper abdomen or upper retroperitoneum. These injuries occur both during open and laparoscopic procedures. Oftentimes violation of the pleural space is noted intraoperatively and should be suspected during laparoscopic surgery when excessive diaphragm motion, or billowing, is noted. During open procedures, bubbling noted in the operative field may indicate an occult violation of the diaphragm and pleural cavity. Occult injuries should be considered when hypoxemia or dyspnea is discovered in the postanesthesia recovery unit. However, clinical manifestation of pleural space injury is variable, ranging from an asymptomatic small apical pneumothorax to a large tension pneumothorax that may lead to hemodynamic instability.
Pneumothorax
Gas may enter the pleural cavity through several routes. These range from patent congenital diaphragm defects to direct injuries to the diaphragm, chest wall, or via musculofascial planes of the diaphragm and mediastinum during insufflation with carbon dioxide (CO 2 ). The volume of gas that enters the pleural cavity determines the degree of pneumothorax (PTX). Small amounts of gas often do not increase the pressure in the pleural cavity above atmospheric pressure, and thus clinical symptoms may not develop. Often these PTX are detected on chest radiograph and do not demonstrate mediastinal shift or represent clinically significant entities. As the amount of gas increases, the pressure in the affected pleural space increases above atmospheric pressure, eventually compressing the ipsilateral lung. Mediastinal shift to the contralateral hemithorax and flattening of the ipsilateral hemidiaphragm are classically noted on radiograph.
Reported rates of PTX following urologic surgeries range from 0.6% to 25%. The rates for PTX following laparoscopic surgeries appear lower (0.6% to 8.5%).
Management of PTX begins with clinical suspicion. When noted intraoperatively, the anesthesiologist should be informed to confirm hemodynamic and respiratory stability. Once established, repair of diaphragm injury should be performed using running, absorbable suture. Prior to closure of this suture, a red rubber catheter can be introduced into the pleural space with its distal end submerged under water or saline. The anesthesiologist then ventilates the patient in order to evacuate gas from the pleural space via the catheter until no further bubbles are noted from the red rubber catheter. The catheter is removed when the diaphragm suture is tied down. This approach can be performed with equal effectiveness for both open and laparoscopic procedures and is necessary when repairing diaphragmatic incisions used during thoraco-abdominal approaches. In the case of a diaphragmatic excision due to malignancy, successful mesh replacement of the diaphragmatic defect secured with nonabsorbable sutures has been reported.
Despite the low rates of these injuries, clinical suspicion for occult injury should remain. Postoperative hypoxemia or dyspnea should be investigated with chest radiography. If central venous catheterization was performed for intraoperative fluid management, postoperative chest radiography should be performed. Routine use of postoperative chest imaging may identify small PTX without clinical sequelae. These can be safely managed conservatively and followed with serial chest radiograph. In the event that a large PTX is noted, management with a tube thoracostomy is recommended.
Chylothorax
Chyle accumulation within the pleural space is a rare complication. Case reports describe chylothorax following retroperitoneal surgeries; however, these occur in conjunction with chylous ascites and subsequent communication into the pleural space. Management includes diagnosis through thoracentesis and treatment of the underlying lymph leakage. Successful pleural space drainage and sclerotherapy have been reported.
Hemothorax
Accumulation of blood within the pleural space following urologic surgery is also a rare complication, with only a few case reports available. Abreu et al. report one case (0.08%) in their review of 1129 patients undergoing laparoscopic urologic surgery. In this case, an intercostal artery was injured, and repair required emergent open thoracotomy. Additional case reports describe hemothorax following laparoscopic pyeloplasty, laparoscopic cryoablation of renal masses, and percutaneous nephrolithotomy. Management requires identification of the bleeding source and possible tube thoracostomy.
Hydrothorax
Iatrogenic instillation of irrigation fluid into the pleural space may result in hydrothorax. Hydrothorax has been reported as a complication following percutaneous nephrolithotomy. Supracostal percutaneous nephrolithotomy may result in higher risk than standard approaches. Management may require tube thoracostomy. For additional discussion of hydrothorax, please refer to the section below regarding percutaneous nephrolithotomy.
Pulmonary Embolism
Pulmonary embolism (PE) results from venous thromboembolism (VTE) and is a potentially fatal pulmonary complication. Prior to use of VTE prophylaxis, studies estimated the incidence of deep vein thrombosis (DVT) in hospitalized patients to range between 10% and 80%, with fatal PE ranging from 0.1% to 7% in patients undergoing elective surgery. While DVT prophylaxis has decreased these rates, VTE and PE remain serious postoperative complications.
Risk for postoperative patients varies depending upon multiple factors. Significant risk factors include age, prior VTE, history of malignancy, obesity, and hypercoaguable state (e.g., Factor V Leiden) as well as medical comorbidities. The American College of Chest Physicians provides guidelines to risk stratify surgical patients. Many urologic procedures fall into the moderate risk or higher categories.
Strategies for prevention of VTE aim to decrease risk of subsequent PE. Nonpharmacologic approaches employ frequent, early ambulation, compression stocking, and pneumatic compression devices and may be sufficient for patients who are very low or low risk. In patients who are moderate or higher risk, including pharmacologic prophylaxis is preferred. Pharmacologic prevention must be balanced with potential for bleeding complications in the perioperative period. Options for pharmacologic prevention include unfractionated heparin, low-molecular-weight heparin, fondaparinux, and novel oral antithrombotic agents (e.g., rivaroxaban, dabigatran, apixaban). Regional and spinal anesthesia should be considered for higher risk patients undergoing lower abdominal or pelvic urologic procedures as these have been associated with a decreased risk of PE when compared with general anesthesia.
The clinical presentation of PE is varied and nonspecific. Patients may be asymptomatic but may also experience sudden shock and death. The most common symptoms of PE, according to two large prospective studies, are dyspnea (73%), pleuritic chest pain (44%), cough (37%), orthopnea (28%), calf/thigh pain/swelling (44%), wheezing (21%), and hemoptysis (13%). Despite these clinical indicators, patients with large PE may report mild or no symptoms. The most common clinical signs include tachypnea (54%), calf/thigh swelling/edema/erythema (47%), tachycardia (24%), and rarely fever (3%). Unfortunately, given the nonspecific nature of this clinical presentation, the sensitivity and specificity for PE on clinical evaluation are 85% and 51%, respectively.
Clinical suspicion for PE in the postoperative phase prompts urgent investigation. Multiple clinical calculators may assist with stratifying patients to empiric therapy. For the majority of patients with suspicion for PE, the preferred diagnostic study is a computed tomographic pulmonary angiogram (CTPA). For patients unable to undergo CTPA, ventilation/perfusion (V/Q) scan remains a sensitive but poorly specific test that can be obtained. In addition, lower extremity duplex ultrasound should be obtained to assess for presence of DVT, and, if found, anticoagulation should be initiated.
Once clinical evaluation confirms suspicion for DVT or PE, empiric anticoagulation should be promptly initiated. In postoperative patients anticoagulation may result in bleeding. Absolute contraindications to heparin therapy are active bleeding, severe bleeding diathesis, a platelet count ≤20,000/mm 3 , neurosurgical or ocular surgical procedures performed within the past 10 days, or intracranial bleeding within the past 10 days. In essence these contraindications to anticoagulation serve as indications for placement of an IVC filter. Consideration may also be given to placement of an IVC filter in the setting of recurrent PE while therapeutic on anticoagulation or when bleeding risk outweighs risk of DVT or PE such as poor cardiopulmonary reserve.
If PE embolism results in hemodynamic instability, more aggressive treatment with thrombolytic therapy is indicated. Thrombolytic therapy should also be considered when patients are at high risk of bleeding from systemic anticoagulation or if systemic anticoagulation fails. Finally, for hemodynamically unstable patients who are not candidates for thrombolytic therapy, embolectomy via either catheter-based approaches or open surgical approaches may be warranted.
It is our practice to administer unfractionated heparin preoperatively (5000 units subcutaneously administered prior to surgery) and throughout the perioperative period for all patients undergoing pelvic surgery for urologic malignancy. This practice is also applied to patients undergoing retroperitoneal oncologic surgery when bleeding risk is deemed acceptable.
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