Image-guided central vascular port placement is a commonly performed procedure in the interventional radiology suite. The complication rate of all image-guided central vascular access approaches 7%,1 with the type of complications highly dependent on patient population (ie, infection, thrombosis, hematoma, pneumothorax, arrhythmias, and catheter malposition).2 One of the most commonly cited and studied complications is infection, the rate of which has been shown to be affected by a number of variables, including greater number of lumens,3,4 inpatient status at the time of port placement,5 thrombocytopenia, leukocytopenia, presence of a hematologic malignancy,6–8 treatment with palliative chemotherapy,7 and type of sutures used for wound closure.9,10 Infection is a complication that tends to happen more frequently and occurs earlier than other catheter-associated complications.11
In 2012, Salazar et al12 studied 465 patients who underwent port placement (467 ports) to compare complication rates based on time of port access and found no significant difference in infection rates. This study was limited by a small sample size with only 1 infection out of 467 port placements, making it difficult to generalize the findings. Given the lack of definitive data on the subject, this study aimed to evaluate a larger data set to provide evidence for the development of port access guidelines.
MATERIALS AND METHODS
A retrospective chart review of image-guided chest port placement procedures in the interventional radiology department of a single institution between October 15, 2003, and June 10, 2015, was conducted. Approval was obtained from the institutional review board. The study was compliant with the Health Insurance Portability and Accountability Act, and the need for informed consent was waived. Procedures were identified via a database maintained by the interventional radiology department,13 yielding 3322 port placements (female:male ratio = 1979:1343) with a mean age of 58 years (range, 15–88 y). Procedure reports were reviewed to determine the side of access, the type of port placed (1 vs 2 lumens), and the type of final layer of closure material (Dermabond, Ethicon, Inc., Somerville, NJ; Steristrips, 3M Health Care, Maplewood, MN; Surgiseal, Pfizer, New York, NY; or Dermabond and Steristrips). There were 1172 dual lumen (35%) and 2150 single lumen (65%) port placements. The majority of ports were placed on the right side of the body (2654 [80%]). After deep dermal and subcuticular sutures, the majority of operators applied Dermabond (n = 2081), with the remaining operators using Surgiseal (n = 650), Steristrips (n = 586), and Dermabond and Steristrips in combination (n = 5) as a final closure layer.
All of the port placement procedures were performed in the interventional radiology suite by 5 experienced interventional radiologists (3–22 years of experience; 12.4 years mean). Intravenous (IV) sedation was administered with fentanyl and midazolam in all cases. Antibiotic prophylaxis of 1g IV cefazolin (or 500 mg vancomycin in the setting of penicillin allergy or 600 mg clindamycin as last line) was given preprocedure. Jugular venous access was performed under ultrasound guidance. Port pocket incisions were closed with interrupted deep dermal stitches with 2-0 synthetic absorbable braided suture material followed by running subcuticular stitches with 4-0 synthetic absorbable braided suture material.
The health record and procedure report were reviewed for each placement to determine the time of initial port access. Initial port access was defined as immediate (in the procedure room for use on the same calendar day) versus nonimmediate (all other time frames). Immediate access was noted by the attending interventional radiologist in their dictated procedure report. Immediate access was always obtained under the original sterile field in which port placement occurred. This was done by the operating team. By these criteria, 945 ports underwent immediate access, and the remaining 2377 ports underwent nonimmediate access.
Nonimmediate access was obtained by a variety of practitioners, ranging from infusion center nurses to inpatient oncology nurses. If the practitioner was from the medical center at which this study was conducted, they adhered to the standards of practice of the facility. This includes having both online training and in-person, on-the-job training from experienced practitioners on how to access a port under sterile conditions. Competency is assessed yearly. The technique for accessing and deaccessing a port adheres to the Infusion Nurses Society (INS) Infusion Therapy Standards of Practice (the Standards).14
Primary end point of infection was defined by criteria adapted from existing Centers for Disease Control and Prevention surgical site infection classification guidelines15 and was continually reviewed throughout the study period with updated criteria.16,17 All of the records were searched for 30 days after placement for the presence of a positive blood culture drawn from a port and for presentation with signs and symptoms of port pocket infection, both of which were considered evidence of infection. Cultures were drawn within 30 days of port placement to qualify for analysis in this study. Positive cultures documented as a contaminant were excluded. The need for removal of the port was deemed unnecessary as a criterion for the primary end point of infection. All infectious organisms (including coagulase negative staphylococcus) were documented. A total of 64 ports (1.93%) met 1 or both criteria of infection within 30 days of placement.
Secondary end point of infection requiring port explantation was reviewed. Of the 64 ports that met the primary end point criteria for infection, 23 (35.9% of infected ports, 0.69% of overall ports) required explantation. Twelve of these ports were immediately accessed, and 11 underwent delayed access.
The study subjects and distribution of variables of interest were evaluated by descriptive analysis. Clinical and demographic information was compared between patients with immediate access and those with later access using the Statistical Analysis Software Frequency (SAS FREQ, IBM, Armonk, NY) procedure to generate data tables, including χ2 analysis, Fisher exact test, and likelihood ratios. Logistic regression and analysis was used to account for confounders between the different variables and measure true effect of the 5 variables of interest (patient age, patient sex, type of port [1 vs 2 lumens], side of port placement, and time of initial port access).
Of the 3322 ports placed, 64 met the primary end point of infection within 30 days of placement (1.93% infection rate). Twenty-three ports met the secondary end point of infection requiring port explantation (0.69%). There was no significant effect of sex and side of port placement on infection (P = .237 and .972, respectively). Infection rates were significantly higher in dual lumen devices compared with single lumen devices (P = .006). There was a higher rate of infection in ports immediately accessed as compared with those with delayed access (P = .001; Table 1). In addition, ports immediately accessed were more likely to require explantation due to infection (1.32%) as compared with ports with delayed access (0.47%; P = 0.01).
Blood cultures were obtained from 64 ports (Table 2), with 1 port demonstrating 2 separate positive blood cultures. The most common causative organisms were Staphylococcus aureus (n = 15), coagulase negative Staphylococcus species (n = 13), Klebsiella species (n = 6), and Pseudomonas species (n = 6).
Time of access and number of lumens were further confirmed to confer a significant independent effect on infection rates when accounting for confounding variables through use of logistic regression analysis. As demonstrated in Table 3, only number of lumens and time of access were significant. Closure material, sex, and side of placement did not show significance. According to the logistic regression, adjusting for sex, side of placement, and closure material, immediate access (odds ratio [OR] = 2.102; 95% confidence interval [CI], 1.263–3.497) and dual lumen (OR = 2.071; 95% CI, 1.24–3.459) are associated with greater odds of infection.
Venous ports are placed for a multitude of reasons, including sickle cell disease, benign hematologic diseases, and cancer. In 2020, more than 1 800 000 patients in the United States will have been newly diagnosed with cancer.18 Many of these patients will require vascular access in the form of port placement for therapy. Many oncology patients already possess multiple risk factors for infection related to port placement, including thrombocytopenia, leukopenia,5 and exposure to previous chemotherapy.7 Often, at the time of port placement, there is a presumed urgent need for venous access, making immediate initial access attractive. However, there are limited data on the optimal time to access newly placed chest ports.15 Reliable guidelines for optimal time to initial port access is necessary to minimize morbidity and mortality in this already vulnerable patient population.
When calculating the independent effects of access time and controlling for the other confounders present, it was determined that the sex of the patient, side of placement, and top layer closure material used did not have any statistically significant effect on the rate of infection of a subcutaneously placed port. Previous studies have found that dual lumen devices confer an increased infection rate.3,4 This study has confirmed this finding, with a possible explanation being an effectively doubled risk of infection when accessing the 2 reservoirs of a dual lumen port compared with a single lumen port.
Port explantation was not considered as the primary end point of infection criteria in the current study. Other studies have used only port removal as a clinically relevant end point in the setting of port infection. The broader definition of port infection used in the current study likely contributed to the higher reported port infection rate as compared with previous studies in the literature, which report rates of less than 1%. When analyzing the secondary end point of infection requiring explantation, the intervention rate is 0.69%. Thus, this study demonstrates that even when using the narrower definition of infection (ie, port explantation alone), immediate access remains a statistically significant contributor to infection rate.
Despite the findings of this study, there are some limitations to the data analyzed. The study was a retrospective, single-centered study performed during a period of time when the institution transitioned from paper to electronic health record. This resulted in occasional incomplete or illegible scanned documentation, prohibiting collection of other potentially confounding clinical variables (ie, white blood cell counts, absolute neutrophil count, diabetic status, immunosuppression, and chemotherapy status). Another limitation presented by the health record system was the inability to document exactly when a port was first accessed if it was not within a 24-hour window of placement. This drove the classification of what could be defined as immediate versus nonimmediate access and prevented further temporal stratification of data. In addition, this study did not have a way to account for any port access that was obtained within the first 30 days of placement at any referring/outside facilities. As such, adherence to standards of care for port access cannot be assured, if such access was obtained.
Future studies can be aimed at addressing these limitations, with focus on a wider analysis of the known confounding variables that were not able to be analyzed in this study. In addition, prospective trials can be undertaken to better control for the type of access and consistency of access obtained after 24 hours of placement, which was not obtainable in our study. This would provide further standardization and assurance of adherence to quality guidelines, including the Standards, while also allowing for further stratification of the timeframe in which first access becomes a statistically significant contributor to infection rate.
This study found a higher rate of infection in ports immediately accessed compared with ports with access deferred to later than 24 hours after placement. This data confirmed the previously reported finding that dual lumen ports confer an inherently increased infection rate. In addition, it found a significant additive effect of a dual lumen port and immediate access on infection risk.
This study also demonstrated an increased infection rate with immediate access; however, it did not investigate possible etiologies. Although the underlying cause for an increased infection rate in immediately accessed ports is currently unknown, one possible explanation is an expected increased amount of extracellular matrix proteins within the port pocket immediately after placement due to disruption of tissues during pocket creation. Several studies in other subspecialties hypothesize that Staphylococcus spp., the main causal organism found in this study, use extracellular matrix proteins (glycosaminoglycans, fibronectin, collagen, elastin, etc) to produce a biofilm and subsequent infection in the setting of recently implanted medical devices.19–21 In addition, other studies have demonstrated that Staphylococcus aureus does have significant associations with early infection.22 Additional studies are necessary to elucidate this relationship with respect to ports.
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