Aspiration pneumonitis (Mendelson's syndrome) as perianaesthetic complication occurring in two horses: A case report

Abstract

Summary No published reports on the occurrence of Mendelson's syndrome (pneumonitis caused by aspiration during anaesthesia) in horses were found in the literature. Although the peculiar anatomy of the equine stomach makes horses less prone than other species to regurgitate, gastric reflux may still occur in horses with colic under certain circumstances. The colic horses in this report had in common stomach impaction, abdominal distention and preanaesthetic placement of a nasogastric tube, which was not withdrawn prior to induction. In both cases, a significant volume of gastric reflux was noted pouring from the endotracheal tube during general anaesthesia for exploratory laparotomy. It was hypothesised that the cause of gastric reflux was the combination of increased intra‐abdominal pressure and patency of the cardia, and that inhalation of gastric content occurred at induction, before tracheal intubation. Treatment, which failed to improve oxygenation, consisted of repositioning of the horses to facilitate passive drainage of gastric content from the airways, active suction through the endotracheal tubes, ventilation strategies, improvement of haemodynamics to increase the pulmonary perfusion, and administration of bronchodilators. One horse was subjected to euthanasia owing to poor prognosis. Aspiration pneumonitis should be regarded as a life‐threatening, although rare, perianaesthetic complication in equine colic cases. Patency of the cardia and increased intra‐abdominal pressure are possible predisposing factors. Partial or even total withdrawal of the nasogastric tube prior to anaesthetic induction and tracheal intubation performed with the horse positioned in sternal recumbency may be undertaken as preventive measures in patients at high risk of developing Mendelson's syndrome.

Response to: ‘Are gastric contents usually regarded as sterile?’

“…). Nevertheless, these authors agree with Dr Freeman that broad‐spectrum antimicrobials should be given to equine patients in which aspiration has been observed or strongly suspected, as it was the case for the second horse of the report object of discussion (Monticelli and Adami ).…”

“…Indeed, inflammation and lung injury caused by the acidic gastric content have the potential to dramatically alter alveolar integrity and function even in the absence of bacteria (Marik 2001); in this scenario, the use of antimicrobials is regarded as debatable in humans (Raghavendran et al 2011). Nevertheless, these authors agree with Dr Freeman that broad-spectrum antimicrobials should be given to equine patients in which aspiration has been observed or strongly suspected, as it was the case for the second horse of the report object of discussion (Monticelli and Adami 2019…”

“…We apologise for the potentially misleading information in our article 'Aspiration pneumonitis (Mendelson's syndrome) as perianaesthetic complication occurring in two horses: A case report' (Monticelli and Adami 2019) and we would like to use this opportunity for a further discussion. In human beings, the gastric content is regarded as sterile owing to the presence of gastric acids and therefore low pH that, under normal conditions, prevent the bacterial growth (Marik 2001).…”

Aspiration pneumonitis: Can we prevent it?

“…The case report in this issue by Monticelli and Adami describes two cases of aspiration pneumonitis (Monticelli and Adami ). It is a condition well recognised in human patients (Engelhardt and Webster ; Marik ) and aspiration of gastro‐oesophageal reflux associated with anaesthesia has been reported in other veterinary species (Kogan et al .…”

Are gastric contents usually regarded as sterile?

“…Aspiration of gastric contents by horses under general anaesthesia for colic surgery is an important anaesthetic complication and was discussed in a meaningful manner in a recent report (Monticelli and Adami 2019) and in the accompanying Clinical Commentary (Bennell and Senior 2019).…”