Pinch off Syndrome: A Complication of Implantable Subclavian Venous Access Devices

Pinch off Syndrome:
A Complication of Implantable Subclavian Venous Access Devices1

David H Hinke, MD
Debra A. Zandt-Stastny, MD
Lawrence R. Goodman, MD
Edward J. Quebbeman, MD, PhD
Elizabeth A. Krzywda, RN
Deborah A. Andris, RN

Implantable central venous access deviced place via the subclavian vein may become obstructed by thrombosis, impingement against a vein wall or compression between the clavicle and the first rib. The latter has been termed pinch-off syndrome (POS). Eleven patients with POS were studied, including one whose catheter had fractured and one whose catheter had fragmented. They were compared with 22 matched control patients and 100 consecutive routine clinic patients. Each catheter was graded: 0 = normal, 1 = abrupt change in course with no luminal narrowing, 2 = luminar narrowing, and 3 = complete catheter fracture. POS was present in most (eight of 11) cases within 3 weeks after placement. A grade 1 catheter was common (33%) among control subjects, but grades 2 and 3 were uncommon (1%). Catheter fracture or fragmentation was seen in two of five cases with long-term (> 3 weeks) pinching (grade 2 catheter). The following conclusions were reached: Grade 2 represents significant catheter compression and the potential for serious complications. Grade 1 is of uncertain clinical significance, due to its high prevalence in control subjects.

Abbreviation: ISVAD = implantable subclavian venous access device. POS = pinch-off syndrome.

Long-term venous access is a necessity in many chronically ill patients for the administration of chemoherapy, antibiotics, blood products, and nutritional support. Implantable central venous access deviced become a patient’s lifeline. Major complications include infection and obstruction to flow. The latter may be due to thrombosis, impingement of the catheter port against the vein wall, or catheter compression between the clavicle and first rib if the cathetet was placed via the subclavian vein. Catheter compression, a potentially serious complication, is termed pinch-off syndrome (POS) (1). In this scenario, the catheter is obstructed during administration or withdrawal of fluids, and a chest radiograph demonstrates narrowing of the catheter lumen as is passes between the clavicle and first rib. The obstruction can often be relieved by positional changes of the patient’s shoulder. Not only is the catheter sometimes rendered useless, but, ultimately, catheter fracture and subsequent embolization can occur 1, 2, 3, 4, 5, 6. The raiographic finding of a compromised lumen is important in differentiating POS from other causes of catheter malfunction.

This article review our experience with POS over a 6-year period. We have provided guidelines to help recognize and, we hope, minimize this complication of implantable subclavian venous access devices (ISVADs).

We studied 11 cases of POS from a total of 987 patients in whom Silastic (Dow Corning, Midland, Mich) ISVADs were implanted at our institution between 1982 and 1988. They were classified as having POS by fulfilling the following criteria: (a) there was intermittent inability to administer and withdraw fluids through the catheter that was altered by patient positioning and (b) here were radiographic signs of any narrowing of the lumen of the catheter as it passes between the clavicle and first rib. Two control patients for each case were matched for age ( ą 5 years), sex, and duration of the indwelling catheter (ą 14 days). Catheters in both groups were of various brands and calibers and were either single or double lumen. Catheters were implanted by several different staff surgeons using a percutaneous (800 patents) or cutdown (187 patients) subclavian vein route. Three chest radiographs from each patient with a POS and each control subject were selected for analysis (Table). These included the first postplacement radiograph, one obtained near the midpoint of the period during which the catheter was in placed, and final radiograph obtained before the removal of the malfunctioning device. All radiographs analyzed were obtained with the patient upright and with use of either anteroposterior or posteroanterior projections.

We devised the following radiographic scale of catheter distortion: Grade 0 catheters run a smooth curved course in the region of the clavicle and first rib with no narrowing. Grade 1 catheters show any degree of bending or deviation from a single curved course but no luminal narrowing. Grade 2 catheters show some degree of luminal narrowing while passing beneath the clavicle. The diameter of the narrowed segment was measured and compared with the adjacent normal diameter. Grade 3 catheters have been transected between the first rib and clavicle and have subsequently become embolized (Fig 1).

Figure 1. Examples of catheter grades. (a) Grade 0 is a catheter with a smooth curved course. (b) Grade 1 catheter shows an abrupt bend in the region of the clavicle and first rib but no luminal compromise. (c) Grade 2 catheter shows actual luminal narrowing (arrow). (d) Grade 3 catheters are completely transected at costoclavicular site (open arrow). Embolized distal catheter fragment is seen in the right atrium (solid arrows). Same patient as in c (4 weeks later).

A second set of 100 control patients was obtained to determine the appearance of these devices in a larger population. These cases were collected from the daily reading in the chest radiology section. All control patients were asymptomatic. The same grading scale was used to analyze one chest radiograph per patient. A singe patient (not included in this study) with POS was examined under fluoroscopy. Spot radiographs were taken of the shoulder in various positions to document changes in catheter deformation. A small amount of contract medium was also injected through the affected port to document obstruction (Fig 2).

Results

The number of Silastic implanted subclavian venous access catheters implanted at our institution during a 6-year period from 1982 to 1988 totaled 987. Eleven cases (1.1%) fulfilled the criteria for POS. Although the catheter of all 11 patients were inserted percutaneously, no significant difference between the percutaneious and surgical cutdown techniques was found with use of a x2 test with a 2 x 2 contingency table (P<.11). Most of these cases (eight of 11[73%]) were discovered within 3 weeks of catheter placement (Fig 3). Seven of the eight cases showed grade 2 catheter deformation on the initial postoperative chest radiograph. The eighth patient’s catheter was initially grade 0 but changed to grad 2 at approximately 3 weeks, coincidental with onset of the patient’s clinical symptoms of POS. Delayed appearance of POS was seen in the remaining three cases, at 12, 24, and 37 weeks. In these cases, the catheters were all of grade 1 after insertion but eventually progressed to grade 2. Mean narrowing of the lumen in a grade 2 catheter was 60% (ą standard deviation = 10%).

Figure 2. Intermittent catheter obstruction based on shoulder position. A patient with POS who had an intermittently malfuctioning ISVAD was examined with fluoroscopy. Contrast material outlines the affected (superior) lumen. (a) This lumen was completely obstructed to flow (arrow) when the patient’s arms were at rest while she was upright or supine (a grade 2 deformation). (b) Flow was restored and lumen returned to normal diameter (grade 0) if the patient shrugged her shoulders or elevated her arm (arrow).

Figure 3. Time of presentation with symptoms of POS by each patient. Most patients presented shortly after catheter placement (<3 weeks). Delayed presentation was observed in three cases.

Six of the 11 catheters were removed within 1 - 2 weeks after onset of clinical signs and the radiographic changes. However, the other five patients’ catheters were not removed until much later (range, 3 - 35 weeks), even though the syndrome was present. A single case of catheter fracture (grade 3) and subsequent embolization occurred 5 weeks after placement. In this case, the initial radiograph showed a grade 2 deformation. Another patient’s catheter, which was left in for 21 weeks after the initial grade 2 deformation was seen on a chest radiograph, was found to be fragmented but not completely transected at the time of removal.

Among the matched control patients, the over prevalence of grade 0 catheters was 95%; of grade 1, 5%; and of grade 2, 0%. In the larger series of 100 consecutive control patients, the overall prevalence of grade 0 catheters was 69%; of grade 1, 30% (total among matched control patients and consecutive control patients, 33%); and of grade 2, 1%. None of the control patents had clinical signs of POS.

The statistical significance of number of catheter lumens, site of placement or sex of patient could not be inferred due to the small sample size.

Discussion

POS is a recognized complication of ISADs. It can be recognized on a chest radiograph by oberving luminal narrowing as the catheter passes between the clavicle and first rib. The anatomy in this region explains the cause of this complications. The region of interest is referred to as the costoclavicular space or cervicoaxillary canal (1). It is bounded anteriorly by the clavicle, subclavius muscle, and costocoracoid ligament. Posterior borders are defined by the first rib and anterior scalene muscle. Medially, the clavicle and first rib are joined by the costoclavicular ligament. A malpositioned catheter passes through this space outside the subclavian vein before it pierces the vessel medially. This anteromedial portion of the canal is smaller than the posterolateral region, which contains the subclavian vein. Thus, a catheter located in this areolar tissue is more susceptible to compression between the clavicle and first rib. Furthermore, compromise in the dimensions of the costoclavicular space is caused by movement at the sternoclavicular joint. A properly placed catheter, however, traverses the costoclavicular space within the subclavian vein. This vessel lies in a more capacious region, and thus by geometric considerations it is protected from compression (Fig 4).

Figure 4. The costoclavicular space. Anatomic (a) and diagrammatic (b) representations. If the catheter passes through the areolar tissue of this space outside the vessel lumen (a medical insertion), it is vulnerable to compression by the clavicle and first rib. (c) Repeated compressive and shearing forces act on the catheter as the shoulder is raised and lowered. (d) A more lateral insertion of the catheter allows it to travel within the subclavian vein. This vessel lies in a more capacious region, and thus by geometric considerations it is protected from compression. (Figures b, c, and d reprinted, with permission, from reference 1.)

The forces on a catheter were confirmed by fuoroscopic examination of a patient with POS. This patient had a double lumen catheter in which one of the two ports intermittently malfunctioned depending on the postion of the patient’s arm and shoulder. If the patient’s arms were at her sides while lying supine or standing, catheter luminal narrowing was present and obstruction to the flow of contract medium was noted durring injection into the affected port. However, if the shoulder was elevated or the arm raised above her head, the catheter caliber returned to normal and flow was restored.

Shoulder potitioning may explain the changes in catheter grades seen in patients 1 and 8 (Table). In addition, anecdotal reports of patients with some signs of POS but no radiographic evidence may be explained by this phenomenon. It thus seems logical to obtain chest radiographs of patients with ISVADs with the patient in an upright, arms-at-sides position. This reproduces the everyday shoulder position rather than the unnatural shoulders-rolled-forward potisiton assumed during the taking of a posteroanterior radiograph.

Unfortunately, when viewing a chest radiograph, one cannot determine the point at which the catheter enters the vein. Thus, the likelihood of associated or impending POS cannot be determined on this bases alone.

The important aspect of viewing the chest radiograph is to recognize the grade 2 deformation. This abnormaility was noted within 3 weeks after placement in eight of 11 (73%) cases. The remaining three cases progressed from grade 1 to grade 2 deformation over many weeks (range, 12 - 37). One control patient was noted to have definite grade 2 narrowing but had no clinical dysfunction at radiogrpahy or an 1-month follow-up shortly before the patient’s death. A possible explanation may be that the lumen of the catheter had not been compromised enough for the obstruction to be detected during use. The patient’s shoulder positioning during the taking of the radiograph may also have altered the radiographic appearance of the catheter.

The significance of a grade 1 catheter deformation is uncertain due to it high prevalence in the control patients.

Catheter fracture (grade 3) is a rare finding, with an overall prevalence of 0.1% among all of the Silastic ISVADs implanted in our study. Other insitutuion have reported a higher prevalence of approximately 1% (2,4). The single case of fracture occurred 5 weeks after placement (patient 11), and the case of fragmentation was discovered 21 weeks after placement (patient 7). Our study group contained five patients in whom a grade 2 catheter was left in place for longer than 3 weeks. Thus, fragmentation and/or complete transection occurred in two of the five cases (40%) with long-term (>3 weeks) catheter pinching. It is the repeated compressive and shearing forces on the catheter that are thought to result in fragmentation, with eventual complete fracture and subsequent embolization. According to unpublished accounts, similar fragmentation has also occurred with transvenous cardian pacer leads and other intravenous catheters.

In summary, POS is a phenomenon in which an ISVAD lumen becomes compromised by the mechanical forces acting on it between the clavicle and first rib. This radiographic finding, together with catheter malfunction, defines the syndrome. It is most commonly detected shortly after placement, although delayed presentation is seen. The significance of the syndrome is twofold. Not only is the patient’s lifeline often rendered useless, but, more importnat, the catheter may subsequently fragment and become embolized if left in place. We offer the following guidelines for monitoring patients with ISVADs: (a) Obtain an upright, arms-at-sides chest radiograph immediately after placement, at 1 month after placement, and anytime the catheter malfunctions; and (b) promptly remove catheters from all patients who fulfill the criteria for POS, as well as from patients with radiographic evidence of catheter compression alone.

Acknowledgments: The authors thank Syliva L. Bartz for her expertise and help in preparing the manuscript.
Repinted by permission of the Radiological Society of North America.

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