Continuous Spirometry: An Aid to Monitoring Ventilation During Operation

Abstract

We present six case-reports of patients who experienced inadequate ventilation as a result of endobronchial or oesophageal intubation, or obstruction to the tracheal tube or airway and were monitored with on-line spirometry. The continuously displayed pressure-volume or flow-volume loops may be compared with previously recorded baseline loops. The changing configuration of the curves offers additional and instantaneous information about the cause of increased inspiratory airway pressure, decreased compliance or increased airway resistance. Monitoring flow-volume and pressure-volume loops in conjunction with currently available techniques provides a comprehensive method of monitoring ventilation.

Clinical application of continuous spirometry with a pitot‐based flow meter during equine anaesthesia

“…The loops registered in horses resembled in essence the loops registered during human anaesthesia (Bardoczky et al . 1993).…”

“…The loops registered in horses resembled in essence the loops registered during human anaesthesia (Bardoczky et al 1993). Unlike in human anaesthesia loops registered during equine anaesthesia regularly failed to close completely despite an airtight seal of the cuff.…”

“…During clinical large animal anaesthesia the use of spirometry to monitor ventilation is not routine because of the lack of a reliable and practical method adapted to large animals. In human anaesthesia, technology referred to as side stream spirometry 1 has been used since 1991 and is now commonly applied (Hufmann 1991;Bardoczky et al 1993). This spirometer uses a pitot tube-based flow sensor with an integrated respiratory gas sample port and a dedicated host monitor.…”

In vitro validation of a Pitot‐based flow meter for the measurement of respiratory volume and flow in large animal anaesthesia

“…During large animal anaesthesia, the use of spirometry to monitor ventilation is not routine because of the lack of a reliable and practical method adapted to large animals. In human anaesthesia, technology referred to as side stream spirometry (Datex‐Ohmeda, Helsinki, Finland) has been used since 1991, and is now commonly applied (Hufmann 1991; Bardoczky et al. 1993).…”

Model-based detection of partially obstructed endotracheal tube*

“…During mechanical ventilation, an obstruction is first manifest by elevated inspiratory airway pressure (Paw) during volumecontrolled ventilation or reduced tidal volume during pressure-controlled ventilation (5). However, similar changes in Paw and tidal volume can also be caused by constriction of bronchial airways (6) or chest wall stiffness (7). The low specificity of Paw and tidal volume monitoring hinders the clinician when making a differential diagnosis of bronchospasm.…”