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

Abstract

Calves that have undergone a dystocia are often hypoxic and acidemic, which can result in reduced vigor and subsequent mortality. Methods of field resuscitation of apneic newborn calves are often ineffective and therefore underutilized. This proof-of-concept study aimed to determine the efficacy of the laryngeal mask airway (LMA) as well as the current industry standard method of ventilation, the McCulloch Calf Aspirator/ Resuscitator (MMR) for positive pressure ventilation of neonatal calves. Five LMA models of various sizes were first tested in cadaver heads to assess anatomical fit. Three LMA models in two sizes each were then tested in two anesthetized calves to determine the model best suited to ventilate calves. Next, the selected LMA and the MMR were both assessed for efficacy of ventilation. Six anesthetized calves had hypoventilation induced by administering alfaxalone intravenously. Calves were ventilated for 3 min with the LMA, allowed a brief washout period, then given a second administration of alfaxalone prior to ventilation with the MMR. Serial arterial blood gas analyses were performed prior to ventilation (baseline), at 1, 2, and 3 min during ventilation, and 1 min after ventilation had ceased. Success of ventilation was assessed by monitoring partial pressure of oxygen (PaO2), partial pressure of carbon dioxide (PaCO2), bicarbonate (HCO3-), pH, L-lactate, and hemoglobin saturation (SaO2) in arterial blood. A one-way ANOVA for repeated measures with Bonferroni correction was used to assess the efficacy of ventilation of each device compared to baseline. For the LMA, PaO2, SaO2, and pH were significantly higher than baseline throughout ventilation and PaCO2 was significantly lower than baseline at 1 min of ventilation. For the MMR, PaO2 and SaO2 were significantly higher and PaCO2 and HCO3- were significantly lower than baseline for 1 to 2 min of ventilation. This proof-of-concept study showed the LMA is an effective means of ventilating neonatal calves, as was the MMR.

Size selection of the Ambu AuraOnce laryngeal mask in Chinese men weighing >70 kg: a pilot study

“…[6][7][8] Additionally, various LMA selection methods may be used to choose the most suitable LMA for the patient's laryngeal anatomy. [1][2][3][4] An unsuitable LMA may lead to leaks, unsatisfactory ventilation, or injury. [1][2][3][4] The LMA size in adults is usually determined by weight, but this method could be inappropriate for Chinese men who weigh >70 kg.…”

“…[1][2][3][4] An unsuitable LMA may lead to leaks, unsatisfactory ventilation, or injury. [1][2][3][4] The LMA size in adults is usually determined by weight, but this method could be inappropriate for Chinese men who weigh >70 kg. [1][2][3][4] In the present study, we used the Ambu AuraOnce laryngeal mask.…”

“…[1][2][3][4] The LMA size in adults is usually determined by weight, but this method could be inappropriate for Chinese men who weigh >70 kg. [1][2][3][4] In the present study, we used the Ambu AuraOnce laryngeal mask. It is a first-generation supraglottic airway device constructed from a singlepiece polyvinyl chloride mold and incorporates a 70 preformed curvature that better approximates the airway anatomy.…”

“…A laryngeal mask airway (LMA) is a supraglottic device (either single-use or reusable) that is used to temporarily maintain an open airway for the administration of anesthesia or during life-saving procedures. [1][2][3][4] An LMA is designed to be inserted blindly into the hypopharynx through the mouth (as the hypopharyngeal space where the device will be seated cannot be directly observed 5 ) and to create a seal immediately above the glottis opening. [1][2][3][4] Diverse methods of LMA size selection are available, including methods based on the patient's actual weight, standard weight, sex, height, distance between the nose and chin, tongue width, 6 distance between the mandibular second molars, 7 or distance between the cricoid cartilage and chin.…”

“…[1][2][3][4] An LMA is designed to be inserted blindly into the hypopharynx through the mouth (as the hypopharyngeal space where the device will be seated cannot be directly observed 5 ) and to create a seal immediately above the glottis opening. [1][2][3][4] Diverse methods of LMA size selection are available, including methods based on the patient's actual weight, standard weight, sex, height, distance between the nose and chin, tongue width, 6 distance between the mandibular second molars, 7 or distance between the cricoid cartilage and chin. 8 Sorbello and Petrini 5 found that an important determinant of choosing the correct size of LMA is the patient's height before (or together with) their weight.…”