pHSpec: A paper-based method for accurately measuring blood pH levels and diagnosing perinatal asphyxia at low cost

Overview:

Birth asphyxia accounts for approximately 30% of the 5 million neonatal deaths globally each year and ranks as the second most important cause of neonatal death after neonatal infection. Furthermore, when it is survivable, there is significant morbidity associated with birth asphyxia, including cerebral palsy, cognitive impairment, epilepsy and chronic illness later in life. Accurate and timely diagnosis of PA can allow for appropriate treatment of the newborn in the first hours of life, when treatments can make the difference between life and death. Furthermore, diagnosis at the bedside immediately after birth can provide valuable insight to clinicians who can identify and prevent future causes of PA.

In the U.S., the testing of umbilical cord acid-base analysis is recommended for any newborn at risk for acidosis, due to asphyxia. Umbilical cord pH is the gold standard for diagnosing birth asphyxia and making decisions about care of the newborn after birth. When blood supply to the fetus is interupted, placental gas exchange is affected, respiratory acidosis occurs causing an accumulation of CO2 and a decrease in pH. A pH

We are investigating using spectrophotometric measurement of a small drop of blood applied to a lateral flow strip as a low-cost method of measuring blood pH and subsequently diagnosing and monitoring PA. We first aim to develop a lateral flow strip which incorporates a colorimetric indicator that is sensitive to pH changes. These color changes will then be detected by a low-cost spectroscopy system. Previous work in our lab has developed Bilispec, a low-cost spectrophotometric reader that can measure bilirubin levels and diagnose and monitor neonatal jaundice. With minor changes, such a system could be modified to also read pH levels from a single drop of blood.