Erroneous tidal volume measurement due to malfunctioned spirolog flow sensor

Abstract

Received: June 10, 2015; Accepted: July 27, 2015; Published: August 10, 2015 An 60 year-old obese class I woman (weight 80 kg, height 160 cm, body mass index 31.25) was mechanically ventilated for an abdominal surgery, using Fabius GS anesthesia machine (Draeger Medical, AG &Co, Lubeck, Germany). Before usage, the anesthesia machine had undergone a standard morning operational check up in which all apparatus components passed. A set tidal volume (TV) of 600 ml was installed. Although the expected TV administered to the patient was supposed to be within the range of the predetermined values (600 ml), the actual TV that had been measured by the Spirolog flow sensor fluctuated between 270 to 290 ml only. Physical examination including inspection of gross chest movement and lung auscultation revealed a fairly ventilated patient. End tidal CO2 was around 35 mmHg, peak inspiratory pressure 23-35mmHg and the state of muscle relaxation adequate. Raising the fresh gas flow to 6 liters per minute, switching to manual ventilation mode and compressing the inflated breathing bag with semi-closed adjustable pressure limiting valve to check for leaks did not unveil the reason for a leak neither within the anesthesia machine nor in the breathing circuit and airways surroundings. To rule out an unnoticed miniature puncture in the disposable circle tubing, it was replaced by a new kit and a second leak test was made, which again passed without revealing the source to any faulty element.