Lie Sui An1,2, Loy Shun Ting2, Lee Cheng Chuan3, Kim Soo Joang3, Soh Chai Rick3. 1. Corresponding author: Department of Anaesthesiology, Singapore General Hospital, Outram Road, Singapore 169608. liesuian@gmail.com. 2. Department of Anaesthesiology, Singapore General Hospital, Singapore. 3. Hyperbaric and Diving Medicine Centre, Singapore General Hospital, Singapore.
Abstract
INTRODUCTION: The management of mechanically ventilated patients in the hyperbaric environment requires knowledge of how the physical properties of gases change under pressure and how this affects the operation of the ventilator. The primary objective of this study was to test the performance of the Dräger Oxylog 1000® ventilator in a hyperbaric environment. METHODS: Each of two ventilators was connected to a mechanical test lung system with an in-built pressure gauge. We used a Wright's respirometer to measure the tidal volumes. The same ventilator settings were tested under varying environmental pressures from ambient (101.3 kPa) to 18 meters' sea water (284 kPa) in a multiplace hyperbaric chamber. RESULTS: A decrease was found in tidal volume, decrease in airway pressure and increase in respiratory rate delivered by the Dräger Oxylog 1000 portable ventilator with increasing pressures to 284 kPa. DISCUSSION: These findings can be explained by the operating principles of the Oxylog 1000, which is a time-controlled, constant-volume ventilator that functions as a flow chopper. Even between the two Oxylog 1000 ventilators tested there were different absolute changes in tidal volume, airway pressures and respiratory rates at various depths. Hence, the trend of changes in these variables is probably more important than absolute values. CONCLUSION: In summary, understanding the trend of changes in ventilator variables will allow clinicians to make appropriate corrections in ventilator settings and carefully monitor adequacy of ventilation to prevent adverse ventilator-associated events. The Dräger Oxylog 1000 portable ventilator is an adequate back-up ventilator for use with straight-forward, ventilator-dependent patients undergoing hyperbaric treatment. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.
INTRODUCTION: The management of mechanically ventilated patients in the hyperbaric environment requires knowledge of how the physical properties of gases change under pressure and how this affects the operation of the ventilator. The primary objective of this study was to test the performance of the Dräger Oxylog 1000® ventilator in a hyperbaric environment. METHODS: Each of two ventilators was connected to a mechanical test lung system with an in-built pressure gauge. We used a Wright's respirometer to measure the tidal volumes. The same ventilator settings were tested under varying environmental pressures from ambient (101.3 kPa) to 18 meters' sea water (284 kPa) in a multiplace hyperbaric chamber. RESULTS: A decrease was found in tidal volume, decrease in airway pressure and increase in respiratory rate delivered by the Dräger Oxylog 1000 portable ventilator with increasing pressures to 284 kPa. DISCUSSION: These findings can be explained by the operating principles of the Oxylog 1000, which is a time-controlled, constant-volume ventilator that functions as a flow chopper. Even between the two Oxylog 1000 ventilators tested there were different absolute changes in tidal volume, airway pressures and respiratory rates at various depths. Hence, the trend of changes in these variables is probably more important than absolute values. CONCLUSION: In summary, understanding the trend of changes in ventilator variables will allow clinicians to make appropriate corrections in ventilator settings and carefully monitor adequacy of ventilation to prevent adverse ventilator-associated events. The Dräger Oxylog 1000 portable ventilator is an adequate back-up ventilator for use with straight-forward, ventilator-dependent patients undergoing hyperbaric treatment. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.
Authors: Jacek Kot; Jordi Desola; Antonio Gata Simao; Roly Gough-Allen; Robert Houman; Jean-Luis Meliet; Francois Galland; Christian Mortensen; Peter H J Mueller; Seppo Sippinen Journal: Int Marit Health Date: 2004