• Steeve Giguère, L Chris Sanchez, Andre Shih, Nancy J Szabo, Ariel Y Womble, and Sheilah A Robertson.
• Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0136, USA.
• Am. J. Vet. Res. 2007 Dec 1; 68 (12): 1407-16.

ObjectiveTo determine and compare the effects of caffeine and doxapram on cardiorespiratory variables in foals during isoflurane-induced respiratory acidosis.Animals6 clinically normal foals (1 to 3 days old).ProceduresAt intervals of > or = 24 hours, foals received each of 3 IV treatments while in a steady state of hypercapnia induced by isoflurane anesthesia (mean +/- SD, 1.4 +/- 0.3% endtidal isoflurane concentration). After assessment of baseline cardiorespiratory variables, a low dose of the treatment was administered and variables were reassessed; a high dose was then administered, and variables were again assessed. Sequential low- and high-dose treatments included doxapram (loading dose of 0.5 mg/kg, followed by a 20-minute infusion at 0.03 mg/kg/min and then 0.08 mg/kg/min), caffeine (5 mg/kg and 10 mg/kg), and saline (0.9% NaCl) solution (equivalent volumes).ResultsAdministration of doxapram at both infusion rates resulted in a significant increase in respiratory rate, minute ventilation, arterial blood pH, PaO(2), and arterial blood pressure. These variables were also significantly higher during doxapram administration than during caffeine or saline solution administration. There was a significant dose-dependent decrease in PaCO(2) and arterial bicarbonate concentration during doxapram treatment. In contrast, PaCO(2) increased from baseline values after administration of saline solution or caffeine. The PaCO(2) value was significantly lower during doxapram treatment than it was during caffeine or saline solution treatment.Conclusions And Clinical RelevanceResults indicated that doxapram restored ventilation in a dose-dependent manner in neonatal foals with isoflurane-induced hypercapnia. The effects of caffeine on respiratory function were indistinguishable from those of saline solution.

20 keywords...

hide…