Respiratory Support for Pharmacologically Induced Hypoxia in Neonatal Calves

Abstract

Practical methods to provide respiratory support to bovine neonates in a field setting are poorly characterised. This study evaluated the response of healthy neonatal calves with pharmacologically induced respiratory suppression to nasal oxygen insufflation and to continuous positive airway pressure (CPAP) delivered via an off-the-shelf device. Ten calves were randomised to receive either nasal oxygen insufflation (Group 1, n = 5) or CPAP (Group 2, n = 5) as a first treatment after induction of respiratory depression by intravenous administration of xylazine, fentanyl, and diazepam. Calves received the alternate treatment after 10 minutes of breathing ambient air. Arterial blood gas samples were obtained prior to sedation, following sedation, following the first and second treatment, and after breathing ambient air before and after the second treatment. Oxygen insufflation significantly increased arterial oxygen partial pressure (PaO2) but was also associated with significant hypercapnia. When used as the first treatment, CPAP was associated with significantly decreased arterial partial pressure of carbon dioxide but did not increase PaO2. These results suggest that the use of CPAP may represent a practical method for correction of hypercapnia associated with inadequate ventilation in a field setting, and further research is required to characterise the use of CPAP with increased inspired oxygen concentrations.

Effects of continuous positive airway pressure on respiratory function in sedated foals

“…Alternatively, the administration of supplementary O 2 may enhance metabolic rate, and consequently increase CO 2 production . Previous studies by our group, of respiratory support in neonatal calves, demonstrated a similar increase in PaCO 2 associated with O 2 supplementation . This effect was attenuated by use of CPAP with ambient air, which was interpreted as suggestive of improved ventilatory efficiency and enhanced gas exchange across the alveolar membrane.…”

“…The experimental design in the current study was intended to control for possible effects associated with treatment order. Although no such effect was observed in Group 1 foals, our previous studies in calves have suggested that treatment order:time interactions are an important experimental consideration and indeed, in Group 2 foals, significant interactions were evident for respiratory rate and CO 2 extraction. Reasons for these differences were not investigated in the current study, but it is possible that cumulative effects of prolonged recumbency were more apparent at T4 than was the case at the earlier sampling time.…”

“…A single published report in dogs showed CPAP significantly increased PaO 2 in sedated animals . Studies by our group in calves have suggested that CPAP using ambient air effectively attenuated the hypercapnia observed in calves receiving nasal O 2 insufflation during pharmacologically induced respiratory suppression …”

Assessing the Efficacy of Ventilation of Anesthetized Neonatal Calves Using a Laryngeal Mask Airway or Mask Resuscitator

“…Calves that undergo a dystocia are born weak and are often unable to self-ventilate, resulting in respiratory acidosis, hypoxemia, hypothermia, and perinatal mortality ( 3 ). It is imperative that positive pressure ventilation is initiated to overcome the surface tension of unexpanded lungs ( 11 , 18 ). The LMA has been successfully used to ventilate the lungs of humans, cats, dogs, pigs, and rabbits ( 12 , 14 – 17 ).…”

“…Previously, a human continuous positive airway pressure machine with facial mask was assessed for use in newborn calves with pharmacologically-induced respiratory insufficiency, in a similar study design to the one presented here. However, it only provided modest benefit and required specialized equipment ( 18 ). The LMA and BVM system used in the present study effectively ventilated the calves and the equipment is easily acquired, compact, and portable, and requires minimal maintenance.…”