Study Design, Setting, and Selection of Participants
This study was a prospective observational investigation of PIVC failure. The study was conducted at a large 1100 bed tertiary care center with an annual ED census of greater than 130,000 visits. The Beaumont Institutional Review Board (IRB) approved this study.
Study investigators recruited a convenience sample of ED patients meeting inclusion criteria. Patients aged at least 18 years with anticipated hospitalization of greater than 48 hours and a PIVC placed using direct visualization and/or palpation in the ED were eligible participants. Patients admitted to the high acuity progressive and intensive care units were specifically targeted to increase the likelihood of meeting the minimum hospital length of stay goal of 48 hours. Patients were excluded if they voluntary withdrew or were cognitively impairment. Additionally, if the PIVC was inserted with ultrasound guidance or if the first sonographic assessment could not be conducted within 24 hours of PIVC placement then the patient was not eligible for enrollment. Informed consent was obtained for all subjects prior to enrollment in the study. All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the Declaration of Helsinki.
Study Procedure
After patient enrollment, researchers performed an initial assessment of the patient. Pertinent demographic and clinical data was abstracted from the electronic medical record (EMR) and included age, body mass index, admission blood pressure, admission heart rate, gender, smoking history, pre-existing medical conditions (diabetes, deep vein thrombosis history, clotting disorder, cancer), and use of anticoagulant medications.
PIVC function was confirmed by clinical assessment (per institutional standard), in which a functional PIVC can be flushed without resistance and shows no external signs of unresolvable complication. PIVC complications include pain and/or tenderness, redness, and leaking or swelling around the PIVC site. PIVC failure was defined as failure of functionality based upon the clinical treatment team’s impression. Next, the investigator performed a sonographic evaluation of the PIVC and surrounding area using a uniform scanning technique that has been previously described in the literature.14 Study investigators trained in using ultrasound were responsible for obtaining images. The Mindray M7 Ultrasound Machine with a 14 MHz high frequency linear array transducer was used for all sonographic evaluations. After a small amount of sterile gel was placed on the non-bordered transparent dressing proximal to the PIVC insertion site, the PIVC and surrounding tissue was scanned proximally (towards the heart) 10 cm (length) x 5 cm (width) in short axis extending from the hub of the PIVC. Similar scanning was performed over the same area in the long axis. Appendix A demonstrates scan area. Adequate placement of the PIVC within the vein was confirmed using ultrasound. Gel was wiped off the dressing and skin after the imaging took place.
A series of cine clips (five seconds duration) of the scan area were recorded. All ultrasound images were saved and archived in QPath, a secure and Health Insurance Portability and Accountability Act (HIPPA) compliant storage warehouse for review and interpretation by the Emergency Ultrasound Director. The following measurements were made by post-processing of the original images: catheter-to-vein ratio, length of catheter in vein, angle of insertion, angle of distal tip against vessel wall, vein wall thickness, distance of catheter tip to vessel wall, degree of catheter kinking, and size of thrombus formation (Appendix B).
Investigators performed follow-up ultrasound and clinical assessments on all catheters daily for the life of the PIVC. At each follow-up interval, the researcher documented the time of evaluation and performed a sonographic assessment using the identical method as described above for the initial assessment. These images were also saved and archived similar to the index evaluation.
Clinical staff documents functional status of PIVCs in the EMR as a standard of care measure within our institution. Daily assessment of catheter function was accomplished by reviewing this documentation in the EMR for any notation of catheter failure and complications. If the investigators had any questions or concerns regarding the functionality of the PIVC, clinical staff was brought to the bedside to reassess functionality the PIVC. If the catheter failed or was removed prior to a follow-up assessment, the PIVC failure time, assessment of failure, and reason for line removal was obtained though EMR review and discussion with the nursing staff when possible.
Within 24 hours of PIVC placement, researchers used ultrasound to assess the PIVC site by measuring the diameter of the vein, length of the catheter in the vein, the angle of PIVC insertion, and the angle of the distal tip of the catheter to the vessel wall (Appendix B). After initial assessment of the PIVC, researchers continued to monitor the PIVC and surrounding tissue on a daily basis to follow the progression of the complication. Daily measurements included vein wall thickness, distance of catheter tip to vessel wall, degree of catheter kinking, as well as the assessment of thrombus or subcutaneous edema (Appendix C).
During every ultrasound evaluation, the insertion site was examined by the researcher and assessed using a standardize visual phlebitis scale.9 The participant was considered symptomatic if they received a score of grade 1 or greater based on a standardized phlebitis scale, which includes the presence of erythema, pain, and/or edema at the access site.9 All medications administered through each catheter was queried and cross referenced against known irritants and vesicants, as defined by the Infusion Nursing Society.15 Frequency of administration and dosages were recorded. Beyond vesicants and irritants, the number of overall catheter events were recorded. A catheter event was defined as any instance where fluid was administered through the catheter, including administration of a bolus, initiation of a drip, non-irritant medication administration. Flushing was considered a component of routine care and PIVC maintenance and was not considered an independent event.
Outcome Measures
The primary endpoint was to identify risk factors associated with premature PIVC failure.
Statistical Rationale and Analysis
Continuously measured variables were displayed in terms of mean/average with standard deviation while categorical variables were displayed as frequencies with percentages in parentheses. Univariate, or unadjusted, analysis was performed. Continuous variables were stratified by catheter failure and compared using a Two Samples Independent T-Tests. Categorical variables also were stratified by catheter failure and compared using Chi-Square tests. Odds Ratios (OR) with corresponding 95% Confidence Intervals (95% CI) also were displayed for categorical variables. In addition, univariate logistic regression models were used and results were displayed in terms of Odds Ratios (OR) with corresponding 95% CI and P-Values. Kaplan-Meier Curves were graphically generated to show the difference in time-to-event outcomes in selected characteristics.
Multivariate/adjusted models also were generated as part of this study. Variables included in these models were chosen by all authors based on clinical rationale and the univariate/unadjusted findings. Firth’s Penalized Likelihood was employed to mitigate the potential bias caused by the relatively small sample.16 A multivariate logistic regression model was used. Effect sizes were shown in terms of Adjusted Odds Ratios (AOR) with 95% CI and P-Values for the logistic model.
P-Value < 0.05 indicates a statistically significant finding. All significant findings represent associations as no formal attempts were made to identify cause-and-effect, or causal, relationships. All analysis was performed in SAS 9.4 (SAS Institute Inc., Cary, NC, USA).