Effects of tidal volume, ventilatory frequency, and oxygen insufflation flow on the fraction of inspired oxygen in cadaveric horse heads attached to a lung model.
OBJECTIVE
To measure the effects of tidal volume, ventilatory frequency, and oxygen insufflation flow on the fraction of inspired oxygen in cadaveric horse heads attached to a lung model.


METHODS
8 heads of equine cadavers.


METHODS
Each cadaveric horse head was intubated with a nasotracheal tube that extended into the proximal portion of the trachea. Oxygen was delivered through an oxygen catheter contained within and extending to the tip of the nasotracheal tube. The trachea was connected to the lung model by use of a spiral-wound hose with a sampling adaptor. Eight treatment combinations involving 2 tidal volumes (5 and 8 L), 2 ventilatory frequencies (6 and 12 mechanical breathes/min), and 2 insufflation rates (10 and 15 L/min) were applied to each head. Hand-drawn inspired gas samples were collected and analyzed for oxygen concentrations.


RESULTS
The fraction of inspired oxygen (measured at mid trachea) ranged from 26.8% to 39.4%. Fraction of inspired oxygen was significantly higher with a smaller tidal volume, lower ventilatory frequency, and higher insufflation rate.


CONCLUSIONS
In the study model, measured fraction of inspired oxygen varied with ventilatory pattern as well as oxygen insufflation rate. Clinically, this information could be beneficial for interpretation of data regarding arterial blood gases and hemoglobin saturation and in making appropriate oxygen insufflation decisions for anesthetized horses that are breathing room air.
Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA. mariana.crumley@yahoo.com
Mariana N
MN
Crumley
David S
DS
Hodgson
Scott E
SE
Kreider
D000818:Animals; D002102:Cadaver; D006257:Head / Q000502:physiology; D006736:Horses / Q000502:physiology*; D007320:Inspiratory Capacity; D007327:Insufflation / Q000662:veterinary; D008168:Lung / Q000502:physiology*; D008954:Models, Biological; D010100:Oxygen / Q000008:administration & dosage* / Q000032:analysis; D012123:Pulmonary Ventilation; D013990:Tidal Volume; D013997:Time Factors
D010100:Oxygen