vascular resistance and influence the direction and degree of intracardiac shunts, potentially leading to congestive heart failure Target saturations for this population should be discussed with a cardiologist It is important to note that pulse oximetry measures are dependent on adequate pulse pressure, and so any low perfusion state may lead to falsely low pulse oximetry readings Pulse oximetry is also unable to detect significant hyperoxia or severe hypoxemia The presence of other hemoglobin forms, such as methemoglobin or carboxyhemoglobin, may not be detected by pulse oximetry In any of these circumstances, arterial blood sampling for PaO2 and cooximetry for carboxyhemoglobin or methemoglobin may be needed to better understand the infant’s respiratory physiology Blood Pressure Blood pressure monitoring in the newborn requires specific equipment and interpretation Most commonly, indirect blood pressure monitoring utilizes an occlusive cuff device that functions identically to pediatric and adult cuffs Neonatal blood pressure cuff width should measure approximately 50% of the extremity circumference A cuff that is too loose can result in inaccurate measurement of blood pressure To increase accuracy, the cuff should be placed at the same level as the heart, typically in the upper extremity Normal ranges for blood pressure increase within the first few hours to days of life and are dependent on the infant’s weight and gestational age at birth, and should be interpreted accordingly ( Figs 96.2 and 96.3 )