Power contrast injections through a totally implantable venous power port: A retrospective multicenter study

Abstract

Objectives

To evaluate the feasibility and safety of power injection of contrast media through totally implantable venous power ports during computed tomography scans in oncologic patients.

Methods

The study population consisted of 417 patients who underwent computed tomography scan through a totally implantable venous power port. Clinical data were examined. Logistic regression analysis was used to assess the associations between clinical covariables and computed tomography scan failure.

Results

Successful computed tomography scans were achieved in 534 of 540 examinations (98.9%). Logistic regression analysis showed that contrast media above a 350 concentration was significantly associated with computed tomography scan failure (95% confidence interval: 1.01–1.13, p = 0.012). No major complications were noted.

Conclusions

Power injection of contrast media through a totally implantable venous power port for computed tomography examination is feasible and safe. This procedure provides an acceptable alternative in oncologic patients with inadequate peripheral intravenous access when computed tomography examination with contrast enhancement is needed.

Keywords

Computed tomography power injector venous port

Introduction

For more than 20 years, totally implantable venous access ports have been used in patients with cancer or chronic diseases.^1,2 Patients with a totally implantable venous access port often undergo a computed tomography (CT) scan with contrast media (CM) injection for clinical examination or follow-up, usually with easy and safe peripheral IV access. However, in some patients, peripheral IV access is difficult, and the implanted venous port is the only access route.³

Power injection of CM for CT scans is beneficial because of enhanced quality and low complication rates.⁴ Recently, high-powered automated injectors and implanted venous power ports capable of withstanding power injectors have been used for high pressure injections.^5,6 However, there are currently no definitive guidelines for injecting CM through this modality.² It is unclear how CM injection via the implantable venous power port was initiated in clinical practice, but contrast enhanced CT has been performed with a power-injectable port system within the manufacturer’s guidelines.^3,4 A few studies have assessed high pressure contrast injection through a totally implantable venous power port (TIVPP).^7–9 Therefore, the aim of this study was to evaluate the feasibility and safety of power injection of CM through a TIVPP.

Materials and methods

Patients

This retrospective multicenter study was approved by the Institutional Review Board of all of the participating hospitals, and the need for informed consent was waved. We retrospectively reviewed the medical records of all 420 oncologic patients who underwent CT scan through a TIVPP between January 2015 and September 2018. A total of 540 CT examinations were performed at three institutions. Patient age ranged from 29 to 86 years (mean age: 60 years; 198 men and 219 women).

The inclusion criteria were as follows: (i) ≥29 years, (ii) jugular vein accessed under sonographic guidance, (iii) implantation of a TIVPP in the chest, and (iv) CT scan performed more than once via a TIVPP. The exclusion criteria were as follows: (i) patients that did not have low resistance flushing or blood returning from the port prior to CT scanning and (ii) use of TIVPP for chemotherapy outside the included clinics. Patient characteristics, used TIVPP, and types of performed CT scans are summarized in Table 1.

Table 1.

Basic patient characteristics.

Variables	Value (range)
Mean age (years)	60 (29–86)
Gender
Male	198 (47.5%)
Female	219 (52.5%)
Type of malignancy (n = 417)
Colon cancer	104 (25%)
Breast cancer	89 (21%)
Stomach cancer	63 (15%)
Lymphoma	54 (13%)
Lung cancer	44 (11%)
Head and neck cancer	17 (4%)
Esophageal cancer	13 (3%)
Biliary cancer	13 (3%)
Others	20 (5%)
Type of TIVPP (n = 417)
DistricAth®	242 (58%)
Celsite®	121 (29%)
Dignity®	54 (13%)
Type of CT scan performed (n = 534)
Portal phase	504 (94%)
Venous phase	16 (3%)
Arterial phase	4 (1%)
Triphasic phase	10 (2%)

CT: computed tomography; TIVPP: totally implantable venous power port.

Values are presented as number (range).

We assessed technical success and complications associated with power injection of CM through a TIVPP during CT examination. Feasibility was defined as the percentage of patients with CM injected successfully through the TIVPP during CT examination. Safety was evaluated by assessing complications in the power injection of CM through the TIVPPs during CT examination. The catheter tip levels were evaluated by comparing all available radiological images (primary chest radiograph, additional CT scans, fluoroscopies, and spine radiographs) of patients that were taken before and after the CT examination. Catheter migration was defined as a ≥3 cm difference in distance of the catheter tip before and after the CT exam in all available radiological images.

TIVPP

The devices (DistricAth® Districlass Medical SA, Saint-Etienne, France; Celsite® B. Braun Medical, Boulogne Cedex, France; Dignity® MedComp, Harleysville, PA, USA) used in this study are approved for high pressure CM injections up to a 5 ml/s infusion rate and a maximum of 300 psi for 19 and 20 gauge needles under the manufacturer’s guideline. The port characteristic specifications are summarized in Table 2.

Table 2.

Port characteristics.

Device	Size (Fr)	Internal diameter (mm)	Pressure limit (psi)	Flow rate (ml/s)
DistricAth®	6	1.3	300	5
Celsite®	6.5	1.1	325	5
Dignity®	6.6	1.35	300	5

Contrast administration protocols

The most recent chest radiograph was evaluated to confirm correct localization of the catheter tip. All TIVPPs were accessed using an aseptic technique and were flushed with a heparinized saline solution before and after CT examination. The ports were accessed with 19-gauge hook-type port needles (Huber needle, Green Medical Supply Co., Gyeonggido, Korea) and connected to power injectors (CT Exprès®, Bracco Injeneering, Lausanne, Swiss; Stellant®, MedRad, Warrendale, PA, USA). All examinations were performed using MDCT scanners (Somatom Definition AS⁺ or flash, Siemens Medical Solutions, Forchheim, Germany). Contrast materials with Iomeprol 350 (Iomeron 350, Bracco Imaging, Milan, Italy), Iobitridol 350 (XenetiX 350, Guerbet, Aulnay-Sous-Bois, France), Iopamidol 300 (Scanlux 300, Sanochemia Pharmazeutika AG, Vienna, Austria), and Iopamidol 370 (Scanlux 370, Sanochemia Pharmazeutika AG, Vienna, Austria) were administered through TIVPPs at rates between 1.2 and 4.0 ml/s, followed by a 20 ml saline flush for CT examinations. We set the pressure cutoff between 150 and 250 psi. The arterial phase was bolus-triggered after the attenuation value reached 100 Hounsfield units in the thoracic aorta. Contrast agent characteristics are shown in Table 3.

Table 3.

Contrast media.

Ingredients	Volume (ml)	Viscosity (mPa s)	Total dose of iodine (g)	Osmolality (mOsmol/kg)
Ingredients	Volume (ml)	At 37°C	Total dose of iodine (g)	Osmolality (mOsmol/kg)
Iomeron® 350	150	7.5	52.5	620
XENETIX® 350	150	10	52.5	915
Scanlux® 300	140	4.7	42	620
Scanlux® 370	150	9.4	75.5	800

Statistical analysis

Statistical analysis was performed with SPSS software, version 21.0 (IBM, Inc., Chicago, IL, USA). Results are presented as means and SDs (range). Logistic regression analysis was used to calculate odds ratios with 95% confidence intervals (CIs) for the associations between clinical covariables and CT scan failure. Statistical significance was defined as p < 0.05.

Results

The success rate of CT scans with injection of CM through the TIVPP was 98.9%. CT scans failed in six patients due to CM leakage through the catheter in one patient and device disconnection between the port capsule and the needle in five patients. Of the 417 patients, 328 (78.66%) underwent 1, 66 (15.83%) underwent 2, 13 (3.12%) underwent 3, 9 (2.16%) underwent 4, and 1 (0.24%) underwent 5 CT scans through a TIVPP. There were two catheter tip retractions greater than 3 cm after CT examination, with injection of CM through the TIVPP. Port chamber malrotation in the subcutaneous pocket was not observed after power injections. No patients reported TIVPP malfunction immediately after contrast administration; all patients received one or more chemotherapeutic infusions, and all underwent successful blood sampling after the power injections. Most complications were minor contrast reactions, with one allergy reaction, three nausea, and one mild vomiting. No major complications related to power injection of CM through the TIVPP during CT scans were noted. The results are summarized in Table 4.

Table 4.

Power injection of contrast media through a totally implantable venous power port.

Variables	N = 540
Successful CT scan (%)	534 (98.9%)
Contrast concentration (mg/ml)	315.38 ± 21.680 (300–370)
Flow rate (ml/s)	2.098 ± 0.4379 (1.2–4.0)
Pressure (psi)	138.39 ± 29.359 (70–250)
Used contrast volume (ml)	128.41± 21.748 (50–150)
Time interval from port insertion to CT scan (day)	127.85 ± 130.316 (0–601)
Patients who experienced complication due to contrast media (n = 534)	5 patients (0.9%)
Patients with catheter migration (n = 534)	2 patients (0.4%)
Failed CT scan (%)	6 (1.1%)

CT: computed tomography.

Values are presented as mean ± SD (range).

As shown in Table 5, in unadjusted analysis, the odds of CT scan failure for CM above a 350 mg/ml concentration were 11.93 relative to that for a less than 300 concentration of CM (95% CI = 1.21–117.49). This association was statistically significant (p = 0.034). However, flow rate, pressure, and volume used were not associated with CT scan failure.

Table 5.

Crude odds ratios for CT examination failures.

Variables	COR (95% CI)	p-value
CT scan failure
Sex
Male versus female	0.90 (0.12–6.48)	0.915
Age (yrs)
65≥ versus <65	1.03 (0.94–1.13)	0.480
Height (cm)	1.02 (0.91–1.14)	0.730
Weight (kg)	0.92 (0.82–1.03)	0.132
Contrast concentration (mg/ml)300 versus ≤350	11.93 (1.21–117.49)	0.034
Flow rate (ml/s)	2.83 (0.49–16.44)	0.248
Pressure (psi)	1.04 (0.99–1.09)	0.133
Volume (ml)	1.04 (0.92–1.16)	0.545
Duration (days)	0.99 (0.97–1.01)	0.266

CI: confidence interval; COR: crude odds ratio; CT: computed tomography.

Values are presented as mean ± SD (range).

The rate of infection was 5.5%. Time to TIVPP extraction ranged from 10 to 1167 days (mean day: 420 days).

Discussion

Totally implantable venous access ports are widely used in patients with cancer or chronic diseases to administer chemotherapy, parenteral nutrition, and fluid replacement.² Oncologic patients usually undergo a CT scan with CM injection in the staging process and clinical follow-up. In our study, 86 patients underwent repeated CT scans, and all CT scans were technically successful. In one patient, five CT scans were successfully performed without complication or port tip migration. A CT scan through a TIVPP does not require additional vascular access, so this approach could improve the quality of life in patients undergoing repeated chemotherapy.

Previous in vitro studies have shown that injection of CM according to the manufacturer’s guidelines is technically feasible and safe for CT examination using a power injector.¹⁰ Even though there are differences by manufacturers, it is recommended that CT scans be performed so that the injection pressure does not exceed 300 psi and the flow rate does not exceed 5 ml/s. In our study, during the CT scans, the maximum injection pressure was 250 psi, and the maximum flow rate was 4 ml/s, which did not deviate from the manufacturer’s recommendations. The success rate of CT examination in our study was 98.9%. This is consistent with a high success rate in other studies.^2,7,8 This high rate of success can be attributed to the performance of CT scans in accordance with the manufacturer’s guidelines.

However, CT scans with CM injection through a TIVPP failed in six patients in our study. One patient failed the CT scan because of CM leakage through the catheter. The patient had a history of acupuncture in the neck, and acupuncture damage to the lumen of the catheter was identified through a port removal procedure. Although low resistance flushing was identified and blood return was performed through the catheter prior to the CT scan, it is important to recognize that minor damage to the catheter is not easily detectable and, as in this case, could impact procedure integrity. This approach also failed five patients with device disconnections between the port capsule and the needle, after which a conventional type power injector with constant injection pressure was used. After the power injector was replaced with a device that could change injection pressure according to the patient’s condition, no further device disconnection occurred. Therefore, we presumed that a convention type power injector could be one of the causes of CT scan failure, because sudden strong and constant pressure was applied to the port chamber with a small space, and the Huber needle was pushed backward and eventually separated from the port chamber.

The incidence of spontaneous migration of an implantable port catheter is about 0.9–1.8%.¹¹ In this study, the incidence of catheter tip migration was 0.4%. The causes of catheter tip migration are thought to be triggered by changing posture, movement, inherent flexibility of the catheter, high intrathoracic pressure, catheter flushing, and a high infusion flow rate, especially in obese patients or in female patients with large breasts.¹¹ Our study showed that patients with catheter tip migration had a history of breast cancer, and the average infusion rate was not as high as 2.10 ml/s. Therefore, it is possible that there is an association between chest contour change and catheter tip migration associated with breast cancer treatment, because the port chamber is located in the chest cavity with the breast tissue.

Our study showed that CM above a 350 mg/ml concentration was associated with CT scan failure (95% CI =1.01–1.13), and this result was statistically significant (p = 0.012). In general, the viscosity of the high iodine concentration in CM was higher than the viscosity of low iodine concentration in CM; low viscosity fluids distribute more evenly in vessels than do high viscosity fluids.¹² Therefore, it is possible to detach a port device when a strong pressure is applied to the port chamber with a relatively high concentration of contrast agent.

No major complications were observed during the CT scan. Five (0.9%) immediate complications were associated with CM. An allergic reaction was reported in one patient, nausea was reported in three, and vomiting was reported in one. No delayed complications associated with CM were noted. The rate of complications was not significantly different from the incidence of commonly reported CM-related side effects.¹³ Our study shows that power injection of CM through a TIVPP for CT scans does not increase CM-related side effects and is a safe procedure.

There were several limitations to our study. First, the retrospective nature of the study design may have reduced the power of this study. Second, as a multicenter study, the injection protocol was not formalized. Third, there was a patient selection bias because only patients with an interventionally placed TIVPP were enrolled in this study. Therefore, additional analysis and a large prospective study of power injection with CM are needed.

In the future, a power injection of CM through implantable ports may become a common clinical practice, and serious complications could arise. Therefore, institutions should work to establish a consistent protocol and to apply power injection protocols for patient safety and optimal outcomes.

In conclusion, power injection of CM through a TIVPP for CT examinations is feasible and safe. This procedure provides an acceptable alternative in oncologic patients with inadequate peripheral IV access when CT examination with contrast enhancement is needed.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethical Approval

The ethics committee of all of the participating hospitals approved this study (SCMC 2017-10-001).

Guarantor

JHY.

Contributorship

JHY and YGS designed research; RSS, JHY, and JJ collected data; JHY, G-SJ, B-HP, and YGS performed research; G-SJ and B-HP reviewed the statistical methods; RSS wrote the paper; all authors reviewed and approved the final manuscript.

Acknowledgements

We would like to acknowledge Mi Hyeon Jin’s assistance with statistical analysis (Department of Biostatistics, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine).

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