From the Research
The normal range of capillary pH for newborns is typically between 7.25 and 7.35, which may be slightly lower than the normal range for arterial pH in adults due to the stress of delivery and transition to extrauterine life. This range is based on the most recent and highest quality study available, which suggests that a pH <7.20 is considered academic in newborns, with 7% to 9% of newborns having a pH <7.20 1. When interpreting capillary pH in newborns, it's essential to consider the infant's age in hours, clinical condition, and other blood gas parameters such as PCO2 and bicarbonate levels for a complete assessment of acid-base status.
- Key factors to consider when evaluating capillary pH in newborns include:
- The infant's age in hours, as pH values may be slightly lower in the first hours of life
- Clinical condition, such as the presence of respiratory or metabolic disturbances
- Other blood gas parameters, such as PCO2 and bicarbonate levels
- Capillary blood samples are often used in neonates as they are less invasive than arterial samples, though they may read slightly lower (by approximately 0.02-0.04 pH units) than arterial values 1.
- Persistent pH values outside the normal range may indicate respiratory or metabolic disturbances requiring clinical intervention, and the risk of adverse outcomes increases with lower pH values, particularly below 6.9 2.