Low-cost compact diffuse speckle contrast flowmeter using small laser diode and bare charge-coupled-device.

We report a low-cost compact diffuse speckle contrast flowmeter (DSCF) consisting of a small laser diode and a bare charge-coupled-device (CCD) chip, which can be used for contact measurements of blood flow variations in relatively deep tissues (up to ∼ 8 mm). Measurements of large flow variations by the contact DSCF probe are compared to a noncontact CCD-based diffuse speckle contrast spectroscopy and a standard contact diffuse correlation spectroscopy in tissue phantoms and a human forearm. Bland­Altman analysis shows no significant bias with good limits of agreement among these measurements: 96.5%±2.2% (94.4% to 100.0%) in phantom experiments and 92.8% in the forearm test. The relatively lower limit of agreement observed in the in vivo measurements (92.8%) is likely due to heterogeneous reactive responses of blood flow in different regions/volumes of the forearm tissues measured by different probes. The low-cost compact DSCF device holds great potential to be broadly used for continuous and longitudinal monitoring of blood flow alterations in ischemic/hypoxic tissues, which are usually associated with various vascular diseases.

Cost-Effectiveness of Laser Doppler Imaging in Burn Care in The Netherlands: A Randomized Controlled Trial.

BACKGROUND: In patients with burns, an early accurate diagnosis of burn depth facilitates optimal treatment. Laser Doppler imaging combined with clinical assessment leads to an accurate estimate of burn depth. However, the actual effects of the introduction of laser Doppler imaging on therapeutic decisions, clinical outcomes, and costs are unknown. METHODS: A randomized controlled trial was conducted in the Dutch burn centers, including 202 patients with burns of indeterminate depth. In the standard care group, estimation of burn depth was based on clinical assessment only; in the laser Doppler imaging group, clinical assessment and laser Doppler imaging were combined. Primary outcome was time to wound healing. Furthermore, therapeutic decisions and cost-effectiveness were analyzed. RESULTS: Mean time to wound healing was 14.3 days (95 percent CI, 12.8 to 15.9 days) in the laser Doppler imaging group and 15.5 days (95 percent CI, 13.9 to 17.2 days) in the standard care group (p = 0.258). On the day of randomization, clinicians decided significantly more often on operative or nonoperative treatment in the laser Doppler imaging group (p < 0.001), instead of postponing their treatment choice. Analyses in a subgroup of admitted patients requiring surgery showed a significant earlier decision for surgery and a shorter wound healing time in the laser Doppler imaging group. Mean total costs per patient were comparable in both groups. CONCLUSIONS: Laser Doppler imaging improved therapeutic decisions. It resulted in a shorter wound healing time in the subgroup of admitted patients requiring surgery and has the potential for cost savings of €875 per scanned patient.

A comparison of laser Doppler imaging with other measurement techniques to assess burn depth.

Evaluation of burn depth is crucial in supporting treatment decisions, yet none of the commonly used methods offer clinicians the desired level of accuracy. This article reviews the literature to determine the advantages of laser Doppler imaging.

New, angle-independent, low cost Doppler system to measure blood flow.

BACKGROUND: A new Doppler flowmeter using a special transducer forming two ultrasound beams to insonate vessels was developed. This low-cost flowmeter allows the flow to be measured independently of the angle of insonation. METHODS: Sixty-five flow determinations were made in the carotid arteries of five pigs. The flowmeter measured the flow in an artery bled into a calibrated vessel. Results were compared with the true volume of the blood captured. RESULTS: On average, 13 measurements per animal were made at different flow rates (80 to 600 mL/min). The flowmeter measured flow-volume rates in mL/min were found to be within +/- 15% of the cylinder captured volume. CONCLUSIONS: The accuracy of the angle-independent flowmeter is comparable with that of flowmeters currently used clinically. The small size and portability, low operator dependency, and low cost suggest potential for continuous acute and chronic-flow monitoring and a potential for an implantable flow-monitoring device.

Reduced cost of extremity free flap monitoring.

We analyzed the results and cost-effectiveness of our protocol for free flap monitoring in extremity patients. Of 70 consecutive free flaps to the upper and lower extremity that were monitored by laser Doppler flowmeter, 62 were managed on the hospital ward immediately after recovery from general anesthesia. The duration of laser Doppler monitoring was 5 days. Perfusion compromise occurred in three flaps, two of which occurred in the recovery room and were initially detected by the laser Doppler and successfully salvaged by early exploration. The average equipment cost for the use of the laser Doppler flowmeter for 5 days was significantly less than the cost of an intensive care unit bed for a single day. Our experience confirms that monitoring free flaps with laser Doppler is cost-effective and indicates that a specialized care bed after the recovery room is not necessary in routine extremity cases. Since no vascular complication occurred beyond the second postoperative day, this study suggests that the duration of laser Doppler monitoring can be discontinued on the third postoperative day.