To evaluate partial pressure of oxygen in arterial blood/fractional percentage of inspired oxygen (PaO2/FiO2) and SaO2/FiO2 ratios (where SaO2 is percentage of oxyhemoglobin saturation in arterial blood), and the correlation between PaO2/FiO2 and SaO2/FiO2, in healthy dogs recovering postoperatively on room air versus nasal oxygen insufflation.Design
University veterinary teaching hospital.Animals
Nineteen dogs.Measurements and Main Results
Medical records were retrospectively evaluated for data from a previous prospective study of dogs undergoing ovariohysterectomy, subsequently randomized to receive 100 mL/kg/min of nasal oxygen insufflation (estimated 37% FiO2, n = 9) or room air (estimated 21% FiO2, n = 10) for 2 hours postoperatively. Baseline information was obtained 1 hour intraoperatively, followed by three postoperative time points (10, 60, and 120 min). Data recorded for each time point included FiO2, PaO2, SaO2, PaO2/FiO2, SaO2/FiO2, partial pressure of carbon dioxide in arterial blood (PaCO2), rectal temperature, and arterial blood pH. The PaO2/FiO2 in dogs recovering on supplemental oxygen was significantly higher compared to dogs recovering on room air (516 ± 28 vs. 359 ± 10, P < 0.0001), whereas the SaO2/FiO2 ratio in dogs recovering on supplemental oxygen was significantly lower compared to dogs recovering on room air (268 ± 0.5 versus 448 ± 1.4, P < 0.0001). The PaO2/FiO2 and SaO2/FiO2 ratios demonstrated excellent correlation for both groups at each postoperative time point. In dogs breathing room air, PaO2/FiO2 and SaO2/FiO2 correlation coefficients were 0.90, 0.95, and 0.93 (P < 0.001). In dogs receiving supplemental oxygen, PaO2/FiO2 and SaO2/FiO2 correlation coefficients were 0.94, 0.93, and 0.90 (P < 0.001).Conclusions
In this population of postoperative dogs breathing either room air or with nasal oxygen insufflation, PaO2/FiO2 and SaO2/FiO2 had excellent correlation. Further evaluation into the correlation between SaO2/FiO2 or pulse oximeter oxygen saturation (SpO2)/FiO2 with PaO2/FiO2 in both healthy dogs, and dogs with pulmonary dysfunction is warranted.