Assessment of Lung Injury Based on the Decompression Scheme of Lung Toxicity Dose Unit and K Value.

INTRODUCTION

This study aimed to assess hyperoxic lung injury (HLI) during a heliox dive based on the unit pulmonary toxic dose (UPTD), K index, and equivalent surface oxygen time (ESOT).

METHODS

The UPTD, K index, and ESOT values of each schedule in the Helium-Oxygen Decompression Table of China were calculated. Based on the recommended thresholds, the risk of lung injury was analyzed, and suggestions were proposed to modify certain schedules.

RESULTS

The K index and ESOT were more conservative than UPTD in predicting HLI. After a deeper dive, the UPTD, K index, and ESOT values were generally higher than the recommended thresholds. For schedules in which the UPTD, K index, and ESOT values do not exceed the thresholds, we recommend prolonging time on oxygen with or without reducing time on air, or recommending oxygen inhalation after surfacing, which may improve safety without increasing the risk of lung injury. For most schedules, the lung injury may resolve within 12 hours after surfacing, according to the K index.

DISCUSSION: Decompression schedules can be adjusted in real time according to K or ESOT values, which may improve safety while effectively controlling the risk of HLI.