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Tip Position of Long-Term Central Venous Access Devices Used for Parenteral Nutrition  
From the * Nutrition Support Team and Departments
of Correspondence: Robert DeChicco, MS, RD, CNSD, Nutrition Support Team TT22, Cleveland Clinic, Cleveland, OH 44145. Electronic mail may be sent to dechicb{at}ccf.org. Background: Venous thrombosis is a potential postplacement complication of a central venous access device (VAD). Improper catheter tip position is a predisposing factor, especially when the device is used to administer parenteral nutrition (PN). American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) guidelines recommend that a central VAD used for PN be placed with its tip in the superior vena cava (SVC) adjacent to the right atrium (RA). The purpose of this study is to determine the prevalence of improper central VAD tip position and factors associated with malpositioning. Methods: All adult patients with a longterm VAD (ie, tunneled central venous catheter, peripherally inserted central catheter [PICC], or implanted port) placed before the current admission who were scheduled to receive PN also received chest x-rays to evaluate position of the catheter tip. Position was determined by a staff radiologist. A catheter with its tip ranging from the middle third of the SVC to the RA was considered acceptable; a catheter with its tip in any other position was considered malpositioned. Subjects with multiple VADs or multiple evaluations for the same catheter had the first placement and last evaluation considered. A logistic regression analysis was used to study the univariable and multivariable associations of these factors with tip malposition. Results: Data were collected for catheters in 124 patients, including 74 tunneled catheters (71 Hickman, 2 Broviac, 1 Groshong), 38 PICCs, and implanted ports. Most of the catheters were placed for (81.9%) or chemotherapy (14.5%). Median catheter duration was 1.6 months at time of evaluation. Of 138 catheters ied, 15.9% (95% confidence interval, 10.2–23.1) were sitioned at time of evaluation. According to univariable ysis, factors associated with malpositioned catheters included shorter catheter duration (p = .001), greater ber of lumens (p = .029), venous entry site on the arm (p .001) and catheters placed at institutions other than Cleveland Clinic (p = .007). Additionally, PICCs were likely to be malpositioned at time of evaluation compared with other long-term VADs combined (34.2% vs 9.0%; p .001). Conclusions: A high percentage of long-term VADs improperly positioned for PN in the present study. were more likely to be malpositioned at time of evaluation compared with tunneled catheters and implanted These findings suggest the tip position of long-term should be confirmed before infusing PN. Catheter-related thrombosis, a deep venous thrombosis (DVT) associated with a venous access device (VAD), is a common clinical problem. In a review of the literature, Kuter et al1 reported symptomatic catheter-related thromboses in an average of 12% (range, 5%–41%) of cancer patients with long-term VADs. In studies that included asymptomatic thromboses, the average incidence increased to 41% (range, 12%–74%). The majority of these thromboses are believed to develop within the first few days after catheter placement.2 Although upper extremity venous thrombosis was originally viewed as a relatively benign event, it is now known that significant complications can arise, including septic thrombophlebitis, superior vena cava (SVC) syndrome, loss of vascular access, and pulmonary embolism. Monreal et al3 reported that 13/79 (16.5%) patients with a catheter-related venous thrombosis of the upper extremity developed a pulmonary embolism, and 2/13 (15.4%) subsequently died in spite of adequate heparin therapy. There are several known mechanisms responsible for catheter-related thrombosis, including injury to the endothelial layer of the vein that occurs during catheter placement, which leads to activation of clotting factors and platelets. Risk factors associated with catheter-related venous thrombosis include traumatic catheter insertion, history of central VAD, history of DVT, presence of malignancy, dehydration, catheter size and composition, and catheter tip location.1,4,5 Incidence of venous thrombosis is higher in patients with a catheter tip located in the upper SVC compared with the lower SVC or right atrium (RA).6–8 Current guidelines from the American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) recommend a central VAD used for PN be placed with its tip in the SVC adjacent to the RA.9,10 Proper catheter tip position is critical with a longterm VAD (ie, tunneled catheter, peripherally inserted central catheter [PICC], or implanted port) used for PN because the device is designed to remain in place for an extended period of time. For hospitalized patients, catheter tip position can be easily verified if the device was placed during the current admission by reviewing the placement report or radiograph. However, determining initial tip position of catheters placed before the current admission can be problematic, especially if the device was placed at another institution or in the distant past. It may be assumed a long-term VAD is safe to use for PN if the tip was properly positioned at time of placement and there is no evidence of dislodgement or migration, but our clinical experience tells us differently. Even if a catheter's tip position at time of placement is acceptable, it may migrate over time. The purpose of this study is to determine the prevalence of improper catheter tip position in PN patients with long-term central VADs.
The Cleveland Clinic is a tertiary referral center with a 1000-bed hospital that cares for both pediatric and adult patients. The Nutrition Support Team (NST) is involved in the care of all adult inpatients that require PN and manages nearly 1400 patients each year. It is our practice to obtain radiographic confirmation of tip position in all long-term central VADs used for PN. We began to collect data on tip position for long-term VADs after recognizing a modestly high rate of tip malposition in patients referred from other healthcare facilities. Maintenance of this database was approved by the institutional review board. The following data are part of a prospective case series study, with the inception of data collection starting at time of consultation for PN. Confirmation of catheter tip position at time of placement was obtained retrospectively. A detailed catheter history was obtained in all adult patients with long-term VADs who were scheduled to receive PN. Information on catheters placed at outside institutions was obtained by reviewing procedural records, if available. Catheter history included date of catheter placement, type of catheter and number of lumens, method and reason for placement, location of venous entry, catheter tip position at time of placement, and institution where the catheter was placed. For tunneled catheters, the location of the exit site, whether the catheter was sutured at time of placement and, if so, whether the suture was still present at time of evaluation for PN were recorded. VAD tip position at time of placement was noted to be in one of the following locations: RA, lower third of the SVC, middle third of the SVC, upper third of the SVC, other, or unknown. Demographic information for each patient included age, gender, primary diagnosis, and reason for PN. Chest x-ray confirmation of tip placement was performed before central PN infusion in all patients with a long-term VAD if the catheter was placed before the current admission. An existing chest x-ray was used for confirmation, providing it was performed during the current admission and the location of the catheter tip was clearly visible. If one was not available, a standing upright chest x-ray with both posteroanterior and lateral views was ordered. All films were interpreted by an NST fellow and one of several staff radiologists whose primary responsibility is to read a variety of thoracic studies. Catheter tip position at time of evaluation was categorized as one of the following: RA, lower third of the SVC, middle third of the SVC, upper third of the SVC, innominate, subclavian, internal jugular, or other. Although some of these films were ordered to document VAD tip position, the radiologists were unaware of the ongoing survey. If catheter location was not clearly stated on the x-ray report or the study was equivocal, an NST fellow reviewed the film in person with a staff radiologist. If catheter tip location could still not be determined, a new film was ordered. The main purposes of this study were to assess how often long-term central VADs were improperly positioned before PN infusion and to determine if catheter or patient characteristics were associated with malpositioning. We defined acceptable catheter tip position to range from the middle to lower third of the SVC or RA. Any other catheter tip position was defined as malpositioned.
Descriptive statistics were computed for all factors. These include
medians, 25th and 75th percentiles for continuous
factors, and frequencies for categorical factors. Rate of improperly placed
VAD tips was estimated by calculating the percent of improperly placed tips at
time of evaluation. The corresponding 95% confidence interval (CI) was also
estimated using the exact binomial method. Wilcoxon rank sum tests for
continuous factors and Pearson's
Data were analyzed starting from inception of the database in March 2005 through June 2006. Information was collected for a total of 151 tip placements in 125 distinct subjects. Of these 125 subjects, 1 was excluded due to data entry errors in placement/evaluation dates. If multiple evaluations per catheter were recorded, the last evaluation was considered. A total of 124 subjects were included in the analysis; 110 of these had 1 catheter placed and 14 had 2 placements, for a total of 138 VAD tip placements. Of these 124 subjects, 76 (61.3%) were women and 48 (38.7%) were men. The primary diagnosis was cancer in 40 (32.3%), inflammatory bowel disease in 35 (28.2%), ischemic gut in 7 (5.6%), obesity in 5 (4.0%), and other in 37 (29.8%) subjects, whereas the reason for PN was malabsorption in 33 (26.6%), obstruction/ileus in 47 (37.9%), fistula/leak in 25 (20.2%), and other in 19 (15.3%) subjects. VAD characteristics are illustrated in Table I. The primary indication for catheter placement was PN in 113 (81.9%), chemotherapy in 20 (14.5%), home IV antibiotics in 2 (1.4%), and other in 3 (2.2%) patients. The number of lumens for each device was single in 66 (47.8%), double in 59 (42.8%), and triple in 13 (9.4%). Median catheter duration was 1.6 months. Tunneled catheters (n = 74; 53.6%) made up the majority of devices followed by PICCs (n = 38; 27.5%) and implanted ports (n = 26; 18.8%). A nearly equal number of catheters were placed at our institution (n = 74; 53.6%) and in outside institutions (n = 64; 46.4%). VAD placement on the right side was more common, with the right internal jugular vein (n = 59; 42.8%) used most frequently for tunneled and implanted catheters. PICCs were placed most frequently via the basilic vein (34/38; 89.5%). Over half of the catheters were still sutured at the time of assessment (43/79; 54.4%). At time of evaluation, 116 (84.1%) of the catheter tips were in an acceptable position and 22 (15.9%; 95% CI, 10.2–23.1) were malpositioned.
A catheter tip was considered to be malpositioned if located anywhere other than the middle to lower third of the SVC or RA. Because of the number of categories and number of events within each category, venous entry was reorganized into 2 factors: arm/neck/chest/other and right/left. "Other" in this case was defined as venous entry via the femoral vein or inferior vena cava, with a catheter exit site on the leg, abdomen, or back. The interaction between these 2 factors was not statistically significant (p = .99), suggesting it was not necessary to use all 10 categories. In addition, there were only 3 Broviac or Groshong catheters, none of which were malpositioned, and 26 implanted ports, of which 3 were malpositioned. Because these low counts would have invalidated the regression model, this category was reorganized into PICC vs other after verifying that the associations of PICC vs Hickman and PICC vs implanted port/Broviac/Groshong were not significantly different. Also, because the number of catheters with an unknown position at time of placement was high, this factor was not included in the multivariable analysis. Information on tip position at time of placement was available for 78 catheters (Table II). Of these catheters, 51 had tips in the RA, 18 in the lower third of the SVC, and 2 in the middle third of the SVC. Seven (9.0%) of the 78 catheters were malpositioned at time of placement, including 3 with tips in the upper third of the SVC and 4 in other locations. Of the 71 catheters in an acceptable position at time of placement, 5 (7.0%) became malpositioned at time of evaluation: two of the 5 catheters had tips the upper third of the SVC, 1 was in the innominate, and 2 were in other locations.
The univariable analysis suggested catheters were more likely to be malpositioned with shorter catheter duration (p = .001), greater number of lumens (p = .029), and venous entry site on the arm (p < .001). PICCs were more likely to be malpositioned (p < .001) compared with all other long-term VADs combined. Of the 9 catheters malpositioned at time of evaluation that were not PICCs, 6 were Hickmans and 3 implanted ports. Last, catheters placed at outside institutions were more likely to be malpositioned at time of placement (p = .001). The type of catheter was significantly associated with the institution where it was placed (p < .001). At our institution, 85% of catheters placed were Hickman, whereas only 4% were PICCs. Conversely, 54.7% of catheters placed at other institutions were PICCs and 29.7% implanted ports. There was no significant association between malpositioning and venous entry location or side for PICCs (p = .33). The final model for multivariable logistic regression analysis consisted of type of catheter, number of lumens, institution where catheter was placed, and venous entry location (Table III). Adjusting for all factors in the model, the only factor found to be significantly associated with tip malpositioning was venous entry location. Compared with catheters placed on the neck, catheters placed in locations other than the arm, neck, or chest were 14.7 times (95% CI, 1.73–125.77) more likely to be malpositioned at time of evaluation (p = .01). The parameter estimate for arm venous entry was set to zero as it is a linear combination of the catheter parameter because only PICCs were placed in the arm.
The association between catheter tip position and venous thrombosis is well established. Luciani et al6 performed monthly Doppler US screenings and chest x-rays every 3 months in cancer patients with implanted ports and receiving chemotherapy. Of 145 patients studied, 11.7% developed catheter-related venous thrombosis. Incidence of thrombosis was significantly lower in patients when the catheter tip was in the SVC or at the junction of the SVC and RA compared with "misplaced" tips (5.7% vs 46.2%; p < .001). Similarly, Cadman et al7 reported the incidence of catheter-related venous thrombosis as 2.6% when the tip was in the distal third of the SVC or RA, 5.3% when the tip was in the middle third of the SVC, and 41.7% when the tip was in the upper third of the SVC or thoracic inlet veins in cancer patients with tunneled catheters (p < .0005, proximal vs distal). A possible explanation for the association between catheter tip location and incidence of venous thrombosis is greater chance of damage to the blood vessel wall when the tip is located high in the SVC. This etiology seems to be supported by studies that demonstrate a higher incidence of venous thrombosis with left-sided compared with right-sided catheter placement.11,12 It is believed that the acute angle between the left innominate vein and the SVC increases the likelihood of damage to the blood vessel wall from catheter-induced trauma. Possible reasons for catheter tip malposition include incorrect positioning at time of placement and postplacement migration. Incorrect positioning at time of placement may be inadvertent due to operator error, or intentional, as when the intended use of the catheter is for a therapy other than PN. Postplacement catheter tip migration may be a result of dislodgement from an external event, such as the catheter being inadvertently pulled by the patient or caregiver, or internal relocation, as when a catheter tip spontaneously flips up from the SVC into the internal jugular vein. These findings suggest that both improper initial placement and postplacement migration contributed to catheter tip malposition. PICCs were significantly more likely to be malpositioned at time of evaluation compared with other longterm VADs combined (34.2% vs 9.0%; p < .001). This finding was not unexpected, because PICCs are not routinely sutured in place at our institution and are therefore more likely to be inadvertently dislodged, considering the exit site on the arm is more exposed than the torso. Also, tunneled catheters are anchored in place by a Dacron cuff and exit site suture, and implanted ports are placed into a subcutaneous pocket, making them less likely to be displaced. Increased prevalence of dysfunction among PICCs compared with other long-term VADs is supported by data from a nationwide study of more than 50,000 patients and 2.8 million catheter-days.13 In this study, the rate of total catheter dysfunction was 1.37 per 1000 catheter-days for PICCs, compared with 0.29 for tunneled central catheters and 0.21 for implanted ports. Although it was not surprising that PICCs were malpositioned more often than other long-term catheters, the incidence of malpositioned tunneled catheters (8.1%) and implanted ports (11.5%) was higher than expected. Because these catheters are less likely to migrate compared with PICCs, this implies that tips were incorrectly positioned at time of placement. Our data are unable to corroborate this due to incomplete information involving catheters placed at outside institutions. Regardless of the etiology, the relatively high percentage of improperly positioned tunneled catheters and implanted ports suggests tip position should be confirmed in these devices. Catheters placed at outside institutions were more likely to be malpositioned at time of evaluation compared with catheters placed at our institution (25.0% vs 8.1%; p = .007). Incomplete records from outside institutions make it difficult to determine whether malpositioned catheters were improperly placed or migrated postplacement. It is known that 54.7% of the catheters placed at outside institutions were PICCs compared with only 4% at our institution. Furthermore, 13 of the 16 (81.3%) PICCs placed at outside institutions were malpositioned at time of evaluation. The predominance of PICCs from outside institutions combined with the high prevalence of catheter dysfunction associated with PICCs seems to explain this finding. Shorter catheter duration and greater number of lumens were associated with catheter tip malposition in the present study. It seems intuitive that catheters are more rather than less likely to become malpositioned the longer they remain in place. While this is probably true, the finding suggests that malpositioned catheters in the present study were detected and replaced or repositioned before the patients were assessed for PN. It is also unclear why more lumens increased the risk of catheter tip malposition. An additional lumen would not affect catheter placement, but perhaps it increases the chance of inadvertent dislodgement during patient care activities. Using multivariable logistic regression analysis, the only factor in our study found to be significantly associated with catheter tip malposition was venous entry site in a position other than the chest, arm, or neck. The arm was not compared with the other locations because only PICCs were placed in the arm, which excluded the other types of catheters. Perhaps the more meaningful finding is that PICCs were marginally associated with catheter tip malposition (p = .093) compared with tunneled catheters and implanted ports combined. Our practice is to reposition or replace malpositioned catheters before infusing central PN. Internal repositioning of catheters that have flipped up into the internal jugular vein can be attempted by having the patient take a deep breath and then vigorously flushing the device with 10 mL of normal saline. PICCs can be pulled back if the tip is too deep into the RA on initial placement. However, most malpositioned catheters require replacement either over a guidewire or to a new site. These procedures can be performed at bedside or in a radiology suite. At our institution, PICCs changed over a guidewire at the bedside require a chest x-ray to confirm tip position, but long-term catheters exchanged in a radiology suite do not. The major shortcoming of this study is missing data involving catheters placed at outside institutions, which comprised almost half of all devices studied. Without complete information on tip position at time of placement, conclusions made from these data should be tempered. Another shortcoming involves the inherent difficulties associated with determining precise catheter tip location. Determining tip position in a clinical setting is an inexact science due to variations in the quality of radiographs, anatomical differences between patients, and skill and experience of the examiner. With a PICC, the position of the arm that contains the catheter can affect tip position. The catheter can migrate down when the arm is elevated during an upright chest x-ray as opposed to a portable chest x-ray, when the arm is usually held along the side of the body. Forauer and Alonzo14 demonstrated that PICC tips moved caudally an average of 2.1 cm in 43 of 61 patients who changed their arm position from abduction to 90-degree adduction. It is also known that catheter tip position can vary depending on the position of the torso. Kowalski et al15 evaluated catheter tip position of long-term VADs, mostly implanted ports, immediately after placement on a supine chest x-ray and again within 24 hours on an upright chest x-ray. Although all catheter tips were in the RA or SVC at time of placement, 49 of 50 catheters migrated peripherally an average of 3.2 cm on the upright chest x-ray. Nazarian et al16 reported similar findings in patients receiving tunneled catheters. Catheter tip position was numbered from 1 to 8, with 1 representing the innominate/SVC junction and 8 representing the lower RA. Catheter tip position changed significantly (p < .0001) on follow-up upright chest x-ray an average of 1.5 catheter positions, usually from the mid-RA to the lower SVC. We attempted to minimize testing variability by ordering all chest x-rays as standing upright, with both a posteroanterior and lateral view, having each film reviewed by both a staff radiologist and NST fellow and reordering x-rays that were considered poor quality. Unfortunately, some of the chest x-rays were portable rather than standard and were performed with the patient in the supine or semiupright rather than the standing upright position. These differences, along with the lack of a gold standard for determining catheter tip position, detract from the precision of the findings. In the present study, a high percentage of long-term VADs was improperly positioned for PN at time of evaluation. Factors associated with malpositioning included type of catheter, shorter catheter duration, greater number of lumens, venous entry site on the arm or leg, and catheters placed at outside institutions. Both improper initial placement and postplacement migration contributed to catheter tip malposition. Considering the association between catheter tip position and catheter-related venous thrombosis and the potential for serious complications stemming from venous thrombosis, these findings support the practice of confirming the tip position on long-term central VADs before initiating PN. Received for publication December 13, 2006. Accepted for publication February 13, 2007.
Journal of Parenteral and Enteral Nutrition, Vol. 31, No. 5,
382-387 (2007)
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MATERIALS AND METHODS
RESULTS
2 or Fisher's exact tests for
categorical factors were used to assess whether there were statistically
significant differences between properly placed and malpositioned catheter
tips at time of evaluation. In order to adjust for possible confounders,
logistic regression analysis was used. The logistic regression analysis
modeled the likelihood of having a malpositioned catheter tip as opposed to a
properly placed tip at the time of evaluation. The final model was selected
using a stepwise selection method. This started with a model containing only 1
constant term, and was assessed by adding or deleting factors from the model
until no additional terms could enter the model based on a p value
> .50 with no factors being eliminated from the model based on a p
value < .20. A .05 significance level was used for all analyses. SAS
version 9.1 software (SAS Institute, Inc, Cary, NC) was used to perform all
analyses.