Description

Yifan L, Wenwu L, Haoze Z, Chenglong L, Jia H, Shifeng W. Assessment of Lung Injury Based on the

Decompression Scheme of Lung Toxicity Dose Unit and K Value. Undersea Hyperb Med. 2026 Third

Quarter; 53(3):433-442.

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.

Keywords: diving; equivalent water surface oxygen time; K index; pulmonary oxygen toxicity; pulmonary

oxygen toxicity dose unit