Deadspace ventilation: A waste of breath!

Pratik Sinha, Oliver Flower, Neil Soni

Research output: Contribution to journalReview articlepeer-review

43 Scopus citations


Problems with ventilatory efficiency results in abnormal CO2 clearance. Measuring deadspace ventilation should be the most reliable method of monitoring ventilatory efficiency in mechanically ventilated patients. Since its first description by Bohr in the late 19th century to the current use of single-breath test for volumetric CO2, our understanding of the physiological deadspace has vastly improved. Yet indices of oxygenation seem to be the mainstay when instigating or fine-tuning ventilatory strategies. Deadspace and with it ventilatory efficiency has been largely forgotten. Recently though there has been a resurgence of interest in ventilatory efficiency. Several indices have been described that either predict deadspace or track ventilatory efficiency at the bedside. Thus making it more accessible and easy to monitor and study in large groups of patients, factors which have perhaps resulted in its under-utilisation in critical care. This review revisits the physiological concepts and methods of measuring deadspace. Described are the various clinical applications of deadspace measurements in the critically unwell. The potential reasons that have led to the variable being under-used are also examined. Finally we describe the indices currently available to track ventilatory efficiency at the bedside.

Original languageEnglish
Pages (from-to)735-746
Number of pages12
JournalIntensive care medicine
Issue number5
StatePublished - May 2011


  • ALI
  • ARDS
  • Dead space
  • Deadspace
  • Ventilatory efficiency


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