Diagnosis and Management of Thoracic Complications of Percutaneous Renal Surgery

34
Diagnosis and Management of Thoracic Complications of Percutaneous Renal Surgery

John R. Bell¹ & Stephen Y. Nakada²

¹ Department of Urology, University of Kentucky, Lexington, KY, USA

² Departments of Urology, Radiology and Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA

Introduction

Percutaneous nephrolithotomy (PCNL) is the recommended treatment modality for renal stones greater than 20 mm in size, staghorn stones, infection‐based stones, and a variety of other indications such as percutaneous renal tumor treatment, stones in kidneys with utereropelvic junction (UPJ) configuration, and for treating stones in patients with urinary diversions [1, 2]. The concept of percutaneous stone surgery was first described by Rupel and Brown in 1941. The authors inserted a cystoscope through a percutaneous nephrostomy tube track in order to treat a renal stone in a solitary kidney [3]. Fernström and Johannson later described the technique of using serial dilation to percutaneously treat a renal stone in 1976 [4]. Since these early descriptions, experience and techniques have expanded and now PCNL is widely performed worldwide. The percutaneous approach means there is a certain risk of injury to structures surrounding the kidney. Therefore, successful utilization of this approach relies on methods to minimize complications and maximize the ability to treat the pathology. Percutaneous access to the kidney is obtained for a number of other indications aside from stone management, such as antegrade management of UPJ obstruction, antegrade management of upper tract urothelial cancer, and percutaneous ablation of renal masses.

There are many possible complications with this approach, yet the proximity of the kidneys to the diaphragm and pleura make thoracic complications a unique and important complication to consider. This chapter discusses the type of thoracic complications that are possible as a result of percutaneous renal surgery. We also review the relevant literature regarding the incidence and management of thoracic complications so that the reader gains an updated management algorithm.

Anatomic considerations

The kidneys are located in the superior aspect of the retroperitoneum, in close proximity to the diaphragm and pleura. The superior pole of the right kidney is typically located slightly superior to the 12th rib, while the superior aspect of the left kidney is often located just beneath the 11th rib [5]. The intercostal spaces are located between the ribs and are named for the rib superior to the space. Therefore, the 11th intercostal space is located between the 11th and 12th ribs. Figure 34.1 demonstrates the anatomic relationships between the kidneys, ribs, and parietal pleura.

Image described by caption. — **Figure 34.1** Relationship of the kidneys, pleura, and ribs. (a) CT image in sagittal section showing the pleural reflection extending down to the 12th rib. Notice that supracostal access would violate the pleura in this patient. (b) Three‐dimensional CT reconstruction of the same patient showing the relationship of the pleura, ribs, and kidneys. The parietal pleura has been colored pink, and the kidneys are gray. Notice that the pleura crosses the 12th rib approximately half‐way along its length.

The lungs are enveloped by two layers of a thin, serous, membrane called the pleura. The parietal pleura lines the internal aspect of the thoracic cavity while the visceral pleura directly surrounds each lung. These two layers of pleura are generally in close proximity with only a small amount of pleural fluid between them that serves as a lubricant, allowing the two layers to slide past each other with minimal friction. The potential space between these two layers is called the pleural space. Thoracic complications arise when significant air or fluid fills the pleural space, causing irritation or compression of the lungs [6].

Posteriorly, in the midscapular line, the parietal pleura attaches to the internal aspect of the 12th rib [7]. At the midaxillary line, the pleural is approximately at the level of the 10th rib and anteriorly, the parietal pleura is approximately at the level of the 8th rib. Posteriorly, the 12th rib curves downward, yet the pleura continues in a relatively horizontal plane, crossing the 12th rib at the lateral border of the erector spinae muscles of the back. In some individuals, the 12th rib is difficult to palpate through the subcutaneous layers, making accurate identification on physical exam difficult [6].

The relative levels of the kidneys and parietal pleura in relation to the ribs means that in many patients the superior aspects of the kidneys are covered by parietal pleura posteriorly [6]. This relationship is an important consideration since many urologists approach percutaneous surgery of the kidney from the posterior aspect.

Incidence, etiology, and risk factors of thoracic complications

Percutaneous nephrolithotomy techniques have improved since the early descriptions, with modern data showing an incidence of Clavien grade III or higher complications of about 5% [8–10]. There is variability in the reporting of thoracic complications. Some studies report all complications detected, many of which are incidentally discovered on postoperative imaging, while others report only complications that were diagnosed based on symptoms. One multicenter study reported the outcomes of 197 patients who underwent PCNL and showed that 111 (56%) had CT evidence of chest pathology on routine follow‐up imaging. However, 88 of these were atelectasis that resolved with conservative measures and only one patient required a chest tube for a hydrothorax [11]. Nevertheless, thoracic complications constitute a significant percentage of the overall complication rate following percutaneous renal surgery with an incidence of 1.8–3.1% [8–10, 12]. The etiology of thoracic complications involves the introduction of air or fluid into the pleural space during or following the procedure.

The proximity of the kidneys to the diaphragm and pleura directly correlate to the risk of thoracic complications. Therefore, the risk of injury to the pleura increases with higher intercostal space access to the kidney. Table 34.1 shows the results of selected studies demonstrating the risk of thoracic complications in relation to the level of access. Munver et al. categorized thoracic complications by site of entry, showing a rate of pleural injury of 4.5% for subcostal access versus 16% for supracostal access. In the supracostal group, 35% of the patients with access above the 11th rib had a pleural injury [13]. Lojanapiwat and Prasopsuk reported a 15.3% hydrothorax rate for supracostal access versus 1.4% for subcostal access. However, only 10 of these patients required drainage. In contrast, nine (5%) of the patients in the supracostal group required drainage [14]. The Clinical Research Office of the Endourological Society (CROES) published data from 5803 patients across 96 worldwide centers showing an overall rate of thoracic complications of 1.8%, all of which were hydrothoraces [10]. These data were then analyzed to evaluate the risk of thoracic complications between patients with upper pole access versus patients with lower pole access. The upper pole access group had a hydrothorax rate of 5.8% whereas the lower pole access group had a hydrothorax rate of 1.5%. This equated to a hydrothorax odds ratio of 0.4 (0.19–0.85) for lower pole versus upper pole access. The odds ratio of hydrothorax for access above the 11th rib versus above the 12th rib was 5.6 (1.97–15.8) [15].

Table 34.1 Review of selected publications regarding thoracic complications following percutaneous renal surgery.

Reference	Study years	Number of patients	Pleural complications	Findings
De la Rosette et al. [10] CROES Data	2007–2009	5660 Total 948 Supracostal 4712 Subcostal	104 (1.8%)	All hydrothoraces
Tefekli et al. [15] CROES Data	2007–2009	3515 Total 403 Upper pole 3112 Lower pole		Lower pole access has 60% lower odds of hydrothorax vs. upper pole Access above the 11th rib has a 5.6× higher risk of hydrothorax compared to access above the 12th rib
Semins et al. [11]	2007–2008	197 Total	17 (8.6%)	Only 1 pt required a chest tube
Bell et al. [16] Lojanapiwat and Prasopsuk [14]	2006–2014 2006 (publication date)	491 Total 346 Supracostal 145 Subcostal 464 Total 170 Supracostal 294 Subcostal	24 (4.9%) 22 (6.4%) 2 (1.4%) 30 (6.5%) 26 (15.3%) 4 (1.4%)	13 Hydrothoraces 11 Pneumothoraces Hydrothorax in 26 pts (15%) with supracostal vs. 4 pts (1.4%) with subcostal access 10 pts (2.2%) required drainage
Muslumanolgu et al. [17]	2002–2004	275 Total 23 Supracostal 252 Subcostal	2 (0.7%) 2 (8.4%) 0	Both hydropneumothoraces
Sukumar et al. [18]	2000–2007	565 Total 110 Supracostal 455 Subcostal	10 (1.8%) 10 (9.1%) 0	All hydrothoraces
Mousavi‐Bahar et al. [19]	2000–2006	671 Total 199 Supracostal 472 Subcostal	5 (0.7%) 5 (2.5%) 0	Pneumothorax (n = 3) Hemothorax (n = 2)
El‐Assmy et al. [20]	1999–2003	1121 Total 141 Supracostal 980 Subcostal	2 (0.2%) 2 (1.4%) 0	Both hydrothoraces
Netto et al. [21]	1995–2000	119 Total 300 Total 98 Supracostal 202 Subcostal	2 (1.7%) 8 (2.7%) 7 (7.1%)` 1 (0.5%)	1 Pneumothorax and 1 hydrothorax
Munver et al. [13]	1993–1999	119 Total 300 Total 98 Supracostal 202 Subcostal	2 (1.7%) 8 (2.7%) 7 (7.1%)` 1 (0.5%)	5 Hydrothoraces (4 in pts with supracostal access) 2 Nephropleural fistulas (both with supracostal access) 1 Pneumothorax (supracostal access)
Desai et al. [12]	1991–2008	773 Total	5 (0.6%)	All pneumothoraces

These data have led some surgeons to prefer lower pole access when possible as it has a much lower rate of thoracic complications and flexible nephroscopy can be used to treat upper and middle calyceal stones [22]. Proponents of upper calyceal access cite improved access to the ureter and better stone clearance rates. Upper pole access is often preferred to treat urinary stones in the proximal ureter, stones associated with UPJ obstruction, upper calyceal diverticulum stones, renal anomalies, and complex staghorn stones [14, 15, 23]. However, the benefits of upper calyceal access must be weighed against the risk of thoracic complications, as upper calyceal access requires a supracostal approach in approximately 70% of patients [15].

When access superior to the 12th rib is preferred, staying lateral to the midscapular line may reduce the risk of pleural injury. Recall that the 12th rib curves downward, while the pleura maintains a mostly horizontal course along the posterior chest. Therefore, staying lateral to the paraspinal muscles may allow supracostal access while decreasing the incidence of pleural injury.

Another risk factor for the development of a hydrothorax is premature withdrawal of the percutaneous access sheath. The percutaneous renal access sheath offers several advantages, it diverts urine and irrigation from the renal collecting system through the center of the sheath and out of the body. This helps to decrease the intrarenal pressures while operating and helps to minimize extravasation of fluid out of the kidney into the retroperitoneum. In terms of thoracic complications, if a pleural injury occurs and fluid is allowed to extravasate, this can travel through the pleural defect and accumulate in the pleural space. This can be done inadvertently when the nephroscope is withdrawn during the procedure. Therefore, care must be taken to ensure that the sheath is not displaced during the surgery. Occasionally the sheath is withdrawn to allow access to nearby calyces. It is recommended that this be done near the end of the procedure to help minimize any extravasation that may occur.

There does not appear to be a significant difference in the rate of thoracic complications for access obtained by a urologist versus a radiologist. El‐Assmy et al. performed a retrospective review of 1121 PCNL surgeries; 661 (52%) were obtained by a urologist at the time of the PCNL and 612 (48%) were obtained by an interventional radiologist prior to the PCNL. There were two hydrothoraces requiring drainage in the cohort, with one being in the urologist access group and the other in the radiology access group. The small numbers of pleural complications did not demonstrate statistical significance between the groups. Interestingly, the urologist group used multiple access points in 230 of the cases and performed a supracostal access in 112 (17%) of the cases. In contrast, the radiologist access group obtained supracostal access in only 29 (4.7%) of the cases [24]. Watterson et al. performed a retrospective review during a similar time frame. The study included 103 patients with 54 patients who had access obtained by an interventional radiologist and 49 patients who had access obtained by a urologist. Again, each group demonstrated one pleural complication during the study which did not show a statistical significant difference between the urologist‐guided group versus the radiologist‐guided group [25]. In studies of this nature, one criticism is that interventional radiologists may be asked to obtain access in the more complicated patients. In addition, in some of the patients who had access obtained by interventional radiologists this may have been done to drain the kidney and not necessarily to access the kidney in a way to best treat the offending stone. However, it is notable that in both studies mentioned, the urologists obtained a higher number of accesses and in the El‐Assmy study did so using a supracostal approach and yet maintained the same complication rate.

The risk of bleeding and hemothorax is similarly increased by supracostal access as thoracic bleeding is often caused by intercostal vessels. Since the neurovascular bundle runs just inferior to each rib, if supracostal access is used, needle access should be done on the superior aspect of the rib below to minimize bleeding [26]. Multiple puncture sites have also been shown to have a higher incidence of bleeding, which may contribute to a hemothorax [17].

There are data to support that operative time, fluoroscopy time, and even overall complication rate decreases with surgeon experience. However, it is unclear if the rate of thoracic complications specifically is affected by surgeon experience [27–29]. There does not seem to be a correlation between dilation method and rate of thoracic complications [30].

Body mass index (BMI) does not appear to have an impact in thoracic complications. Fuller et al. analyzed the CROES database and found no difference in pulmonary complications in relation to patient BMI [31]. Other studies have also corroborated these results [32, 33], and some data have even shown that increasing BMI corresponds to a lower risk of thoracic complications [16]. This is likely because the higher amounts of visceral fat push the kidneys more cephalad, thus creating a greater distance between the diaphragm in the collecting system. Patients who have certain anatomic variations such as horseshoe kidney, pelvic kidney, and malrotation tend to have lower risks of thoracic complications as the kidney is located more caudad [34]. In a study of 54 cases done on horseshoe kidneys, none of them experienced a thoracic complication [35].

Special consideration should be given to patients that have alteration of normal anatomical landmarks such as patients with severe scoliosis, spinal cord injury, and other musculoskeletal deformities. It is often difficult to position these patients on the operating table and the relationship of the pleura to the kidneys is often distorted due to their physical deformities. CT or ultrasound imaging should be considered when obtaining access in these patients to decrease thoracic complications [36].

The risks of a thoracic complication are higher when upper pole access is used as this often violates the pleura. However, this approach offers many ergonomic advantages and allows for superior access for a multitude of conditions. The risks of upper pole access must be carefully weighed against the benefits of this approach. Each patient should be assessed for the optimal access carefully and no one approach will work for every patient.

Descriptions of thoracic complications

Pneumothorax

Pneumothorax is the accumulation of air within the pleural space (Figure 34.2). A pneumothorax results from the introduction of external air into the pleural space as a result of a pleural violation during surgery. Most commonly this occurs during the surgical procedure as air is introduced during renal access or tracks along the access sheath during the procedure. In this instance the source of the air is from outside of the patient’s body. Rarely, injury to the lung parenchyma can occur when obtaining percutaneous renal access. This can result in a tension pneumothorax where air continues to escape from the bronchial tree or alveoli that becomes trapped in the pleural space. Both etiologies can generate a compressive effect against the lung parenchyma if air continues to accumulate in the relatively fixed space of the thoracic cavity.