Aspects of respiration in anaesthetized newborn foals.

This research study investigates respiration in anaesthetized newborn horses, known as foals. The study found that newborn foals at higher altitudes (1300m above sea level) have noticeably lower arterial oxygen levels than ones at lower altitudes without causing any adverse effects even after being under prolonged anesthesia.

Arterial Oxygen Tension in Newborn Foals

• The research indicates that arterial oxygen tension (PaO2), which measures the pressure in the arteries due to dissolved oxygen, in newborn foals located 1300m above sea-level is much lower – less than 60 mmHg (millimeters of mercury). This is a significant deviation when compared to foals of the same age situated at lower altitudes.

Anesthesia and Its Effects

• The study further reveals that when these foals at 1300m are kept under prolonged pentobarbitone anæsthesia, a type of barbiturate anesthetic, the PaO2 decreases even more, i.e., to less than 50 mmHg.
• What is remarkable about this finding is that this further reduction in PaO2 doesn’t seem to produce any harmful consequences in the newborn foals.

Comparison Between Oxygen Dissociation in Newborn Foals and Adult Horses

• The research also took into account certain oxygen dissociation curves. An oxygen dissociation curve is a graph that plots the proportion of hemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis.
• In studying these curves, researchers observed that hemoglobin, the oxygen-carrying protein in red blood cells, becomes saturated at a lower blood oxygen tension in newborn foals compared to adult horses.
• This means, in simpler terms, the blood of newborn foals manages to utilize oxygen more efficiently than adult horses, even when available oxygen is at a lower level.