Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals

Abstract

Objective—To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (Fio2) and other arterial blood gas variables in healthy neonatal foals. Animals—9 healthy neonatal (3- to 4-day-old) foals. Procedures—In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal Fio2, intratracheal end-tidal partial pressure of carbon dioxide, and arterial blood gas variables were measured before (baseline) and during unilateral and bilateral nasopharyngeal delivery of 50, 100, 150, and 200 mL of oxygen/kg/min. Results—No adverse reactions were associated with administration of supplemental oxygen except at the highest flow rate, at which the foals became agitated. At individual flow rates, significant and dose-dependent increases in Fio2, Pao2, and oxygen saturation of hemoglobin (Sao2) were detected, compared with baseline values. Comparison of unilateral and bilateral delivery of oxygen at similar cumulative flow rates revealed no differences in evaluated variables. Conclusions and Clinical Relevance—Results indicated that administration of supplemental oxygen via nasal cannulae appeared to be a highly effective means of increasing Fio2, Pao2, and Sao2 in neonatal foals. These findings may provide guidance for implementation of oxygen treatment in hypoxemic neonatal foals. (Am J Vet Med 2010;71:1081–1088)

Plasma pharmacokinetics and pharmacodynamics of alfaxalone in neonatal foals after an intravenous bolus of alfaxalone following premedication with butorphanol tartrate

“…Although f R s decreased, following induction of anaesthesia, they remained within the range of values for anaesthetised foals (Hubbell & Muir 2009) and apnoea was not reported. Values for arterial PaO 2 , partial pressure of carbon dioxide (PaCO 2 ) and pH in standing healthy foals receiving similar supplemental oxygen flows (approximately 100 mL kg )1 minute )1 ) via a unilateral nasopharyngeal catheter have been reported as 23.4 ± 1.9 kPa (175 ± 15 mmHg), 6.7 ± 0.3 kPa (51 ± 2 mmHg) and 7.42 ± 0.01 respectively (Wong et al 2010). The foals in this study exhibited hypoxaemia, mean ± SD PaO 2 being 10.7 ± 3.6 kPa (80 ± 27 mmHg), the lowest reaching 5.5 kPa (41 mmHg), during the first five minutes of anaesthesia and some hypercapnia at five and ten minute time points was noted.…”

Bi-level positive airway pressure (biPAP) for non-invasive respiratory support of foals

“…Increased PaCO 2 was observed in Group 3 foals following respiratory support, including hypercapnia (PaCO 2 > 60 mmHg) following O 2 administration (two foals) or biPAP (one foal). Hypercapnia has been reported in response to O 2 supplementation in human neonates (28) and foals (13, 29), and may be due to reduced respiratory drive, increased metabolic rate, hypoventilation due to sedation or effects of equipment dead space. As noted above, mask administration of supplementary O 2 was associated with the accumulation of CO 2 within equipment dead space (rebreathing) in the current study, but this was not observed during biPAP.…”

Pathophysiology, diagnosis and treatment of neonatal sepsis

“…Intranasal oxygen supplied via uni‐ or bilateral cannulas allows delivery of flow rates up to 20–30 l/min, which corresponds to an inspired oxygen fraction of 70–78% and greater (Wong et al . ). As oxygen toxicity is a threat with administration of a high FiO 2 for longer than 24 h, the lowest possible flow rate should be chosen.…”

“…Pulmonary dysfunction is a common problem in critically ill equine neonates and may include pulmonary immaturity and surfactant dysfunction, bacterial pneumonia, often associated with sepsis or aspiration, viral pneumonia, meconium aspiration or acute respiratory distress syndrome (Peek et al 2004;Wilkins 2004;Wilkins et al 2007). Intranasal oxygen supplied via uni-or bilateral cannulas allows delivery of flow rates up to 20-30 l/min, which corresponds to an inspired oxygen fraction of 70-78% and greater (Wong et al 2010). As oxygen toxicity is a threat with administration of a high FiO2 for longer than 24 h, the lowest possible flow rate should be chosen.…”