CARDIOPULMONARY EFFECTS OF POSITIONING PREGNANT COWS IN DORSAL RECUMBENCY DURING THE 3RD TRIMESTER

The uterine hemodynamic response to maternal positioning in dorsal rec umbency was evaluated in 7 conscious pregnant cows during the third tr imester. Anesthetic or sedative drugs were not administered. Uterine a rtery flow was measured, using a previously implanted ultrasonic flow probe. Catheters implanted in the uterine artery and vein were used fo r measurement of blood pressure and for blood sample collections. Hear t rate, systemic arterial pressure, uterine arterial blood flow, arter ial and venous oxygen and carbon dioxide tensions, and pH were measure d in cows in standing position. Cows were cast with ropes and position ed in dorsal recumbency, then measurements were repeated at 15 and 30 minutes. Compared with standing measurements, dorsal recumbency caused 50% increase in heart rate and 44% increase in arterial blood pressur e. Uterine artery flow did not change significantly. Despite increased ventilation, arterial oxygenation was reduced during dorsal recumbenc y. There were minimal differences between measurements at 15 and 30 mi nutes of dorsal recumbency.