What should I normally see?
For healthy neonates, T-Stat normally reads 61-69%
T-Stat normals are very DIFFERENT than pulse oximeter normals. This is because the tissues of healthy patients normally remove enough oxygen from arterial blood to drop T-Stat levels 25-35% below the pulse oximeter. Even a well-perfused child with a cardiac mixing lesion (and a low pulse oximeter reading of 70-85%) will still have a T-Stat reading 25-35% below the pulse oximeter, or a T-Stat reading of about 40-55%.
What is abnormal, and what do these readings mean?
There are 2 important ways to think about abnormal T-Stat readings at the bedside. First, consider the T-Stat reading. T-Stat readings below 55% are rarely normal, and indicate an increased risk of inadequate oxygen delivery.
T-Stat values below 35% in children lead to metabolic acidosis by lactic acid production. If left untreated, T-Stat values below 30% may rapidly lead to ultimate failure.
Second, consider the gap between T-Stat and the Pulse Oximeter. The gap between tissue and pulse oximeter readings grows with impaired oxygen delivery.
A difference of 38% or more between T-Stat and Pulse Oximeter suggests an impaired delivery of oxygen to tissue.
Low T-Stat readings and widened Pulse-Tissue gaps
may be caused by:
• Decreased systemic blood flow
(hypovolemia, shock, heart dysfunction)
• Increased left-to-right shunts
(intracardiac, open ductus)
• Increased metabolism (fever, stress, sepsis)
• Changes in drips, medications, or ventilator
settings that worsen perfusion