Cold light, heat burn

The use of near-infrared light for safe and effective visualization of subsurface blood vessels to facilitate blood withdrawal in children

Obtaining access to blood vessels can be difficult, especially in children. Visualization of subsurface blood vessels might be a solution. Ultrasound and visible light have been used to this purpose, but have some drawbacks. Near-infrared light might be a better option since subsurface blood vessels can be visualized in high contrast due to less absorption and scattering in tissue as compared to visible light. Our findings with a multispectral imaging system support this theory. A device, the VascuLuminator, was developed, based on transillumination of the puncture site with near-infrared light. The VascuLuminator was designed to meet the requirements of compact and safe use. A phantom study showed that the maximum depth of visibility (5.5mm for a 3.6mm blood vessel) is sufficient to visualize blood vessels in typical locations for peripheral venous and arterial access. A quantitative comparison of the VascuLuminator and to two other vessel imaging devices, using reflection of near-infrared light instead of transillumination, was conducted. The VascuLuminator is able to decrease failure at first attempt in blood withdrawal in pediatric patients from 10/80 (13%) to 1/45 (2%; P=.05).

Predictive factors for difficult intravenous cannulation in pediatric patients at a tertiary pediatric hospital

BACKGROUND

It is generally believed that certain patient characteristics (e.g., Body Mass Index and age) predict difficulty of intravenous cannulation in children, but there is not much literature evaluating these risk factors. In this study, we investigated predictive factors for success rate at first attempt and time needed for intravenous cannulation.

METHODS/MATERIALS

In a prospective cohort study, we observed characteristics of intravenous cannulations in pediatric patients at the operating room (n = 1083) and the outpatient care unit (n = 178) of a tertiary referral pediatric hospital. Time to successful intravenous cannulation, success at first attempt, and potential predictors for difficult cannulation (age, gender, skin color, BMI or weight-to-age z-score, the child being awake or anesthetized, operator profession and surgical specialty) were recorded. Regression models were constructed to find significant predictors.

RESULTS

Success at first attempt was 73% and 81%, respectively. In the operating room age, operator and surgical specialty were predictive for a successful first attempt and time to successful cannulation. No significant predictive factors were found for the outpatient care unit. BMI or weight-to-age was not related to difficult intravenous cannulation.

CONCLUSIONS

This study shows that in one-fifth to one-third of the patients, intravenous cannulation required more than one attempt. It is difficult to predict with accuracy the difficulty of intravenous cannulation solely with easily obtainable patient characteristics.

Visualizing veins with near-infrared light to facilitate blood withdrawal in children

INTRODUCTION

This study aims to evaluate for the first time the value of visualizing veins by a prototype of a near-infrared (NIR) vascular imaging system for venipuncture in children.

METHODS

An observational feasibility study of venipunctures in children (0-6 years) attending the clinical laboratory of a pediatric university hospital during a period of 2 months without (n = 80) and subsequently during a period of 1 month with a prototype of an NIR vascular imaging system (n = 45) was conducted. Failure rate (ie, more than 1 puncture) and time of needle manipulation were determined.

RESULTS

With the NIR vascular imaging system, failure rate decreased from 10/80 to 1/45 (P = .05) and time decreased from 2 seconds (1-10) to 1 second (1-4, P = .07).

CONCLUSION

This study showed promising results on the value of an NIR vascular imaging system in facilitating venipunctures.

Optical characterization of cutaneous transilluminators for eye safety

Cutaneous transilluminators are light-emitting devices used to localize blood vessels for various medical procedures. They are often used in populations that may be at increased risk for skin burns, such as neonates and the elderly. While there is a known potential for skin burns, little is known about the ophthalmic risk from the use of these devices. This paper will report on the laboratory evaluation of the potential ocular hazards from transilluminators (TIs). Our results indicate that transilluminators which incorporate white-light LEDs have emissions that have the potential for producing injury to the retina, especially in patients who may have a reduced aversion response.

Optical-thermal characterization of cutaneous transilluminators

In recent years, there has been an increase in the popularity of light-emitting diode (LED)-based, battery-powered transilluminators (BPTs) for facilitating transdermal vascular access in adults and neonates. BPTs are believed to have lower potential for inducing skin burns than prior devices based on high-power broadband lamps; however, the optical and thermal outputs of BPTs are not well documented and safety limits for these devices are not well established. In this study, we characterize and assess the optical and thermal outputs of six BPTs that incorporate red, orange and white LEDs. Optical measurements included spectral irradiance and peak local irradiance. Thermal measurements included transient temperature readings for an exposure time of 4 min in ambient air and ex vivo tissue pre-heated to physiological temperatures. The greatest mean temperature rise produced in tissue by a non-white-light diode BPT was 2.5 degrees C, whereas a mean temperature rise of 9.1 degrees C was measured in a BPT that incorporated white-light diodes with relatively high irradiance levels. The dominant cause of temperature rise was most likely heat generation within the devices. Thermal damage analyses based on temperature limits and the Arrhenius equation indicate that although some of the devices studied approach the threshold for damage, none appear to exceed it under normal operating conditions. The results demonstrated that ambient air measurements may be suitable for identifying worst-case BPT temperatures. This study highlights the potential risk of LED-based medical devices as well as the need for additional research on related issues such as neonatal thermal injury thresholds.

Clinical review: vascular access for fluid infusion in children

The current literature on venous access in infants and children for acute intravascular access in the routine situation and in emergency or intensive care settings is reviewed. The various techniques for facilitating venous cannulation, such as application of local warmth, transillumination techniques and epidermal nitroglycerine, are described. Preferred sites for central venous access in infants and children are the external and internal jugular veins, the subclavian and axillary veins, and the femoral vein. The femoral venous cannulation appears to be the most safe and reliable technique in children of all ages, with a high success and low complication rates. Evidence from the reviewed literature strongly supports the use of real-time ultrasound techniques for venous cannulation in infants and children. Additionally, in emergency situations the intraosseous access has almost completly replaced saphenous cutdown procedures in children and has decreased the need for immediate central venous access.