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Mammals (other)
Inadvertent activation of a PEEP valve leading to potentially severe cardiopulmonary complications in a horse
  1. Inga-Catalina Cruz Benedetti,
  2. Martina Argano,
  3. Nina Küls and
  4. Attilio Rocchi
  1. Department of Anaesthesiology and Perioperative Intensive-Care Medicine, Veterinarmedizinische Universitat Wien, Wien, Austria
  1. Correspondence to Inga-Catalina Cruz Benedetti; inga-catalina.cruz-benedetti{at}


A five-year-old Austrian thoroughbred mare underwent anaesthesia and was mechanically ventilated using a Smith respirator L.A.-90. Shortly after commencing, capnography displayed a curve compatible with airway obstruction and haemoglobin saturation decreased progressively. Unexpectedly, positive-end expiratory pressure and peak inspiratory pressure reached 20 cm H2O and 50 cm H2O, respectively. The ventilator was disconnected and the patient ventilated manually, promptly correcting capnography and saturation. A later inspection of the ventilator identified two problems. The expiratory flow regulator, made of two overriding metal rings, was inadvertently rotated, preventing gas from escaping the system during expiration. Additionally, the poorly labelled knob limiting PIP had been left on 50 cm H2O. The authors describe a critical incident due to both, some specific features and limitations of the Smith Respirator L.A.-90, and the lack of familiarity of the anaesthetists with the ventilator. Implementing checklists may guide inexperienced users through the safe use of equipment.

  • Critical incident
  • Anaesthesia
  • Auto-PEEP
  • Anaesthetic equipment
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  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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