Real-Time Tissue Perfusion Monitors

Using T-Stat in Critical Care

Neonatology Brochure

Using T-Stat in Neonatology

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)

•  Anemia

•  Increased metabolism (fever, stress, sepsis)

•  Changes in drips, medications, or ventilator 

   settings that worsen perfusion