Laser Speckle – Wearable Detects Postpartum Hemorrhage

Researchers have created a wearable optical device to detect bleeding during or after delivery early. This severe, profuse bleeding, responsible for about 30% of maternal fatalities worldwide, can be difficult to identify before it becomes an emergency. According to studies, the greatest strategy to avoid mortality from postpartum hemorrhage is to diagnose and treat the condition as soon as possible. The new device is meant to be worn on the wrist, where it continually scans for a drop in blood flow, which might be a clue that significant bleeding is occurring elsewhere in the body. It does this by using laser speckle imaging.

The team has created the wearable device. It employs a laser speckle flow index (LSFI) to detect peripheral vasoconstriction caused by bleeding. LSFI uses a laser and a camera to measure changes in speckle patterns that occur in space and time due to light interacting with moving blood cells to extract information about blood flow. Despite the development of wearable laser speckle imaging sensors for real-time cardiovascular physiology and blood flow monitoring, the researchers still had to devise a wireless, wrist-worn, battery-operated laser speckle system. They also created a rapid speckle processing mechanism to process visual data onboard.

Using a tissue-imitating phantom, researchers tested a wearable laser speckle imaging sensor and saw an almost perfect linear response to blood flow rate. Then, using a swine animal model, they researched bleeding and resuscitation and found a consistent drop in blood flow with an average correlation of 0.94. The laser speckle imaging sensor may follow a patient’s reaction to resuscitation attempts and look for any early indications of postpartum hemorrhage.

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