Medicinski Glasnik (Feb 2009)
Dry diving as a human model of pulmonary microembolization
Abstract
Aim The human model of pulmonary embolism is currently unavailable.The objective of this study was to evaluate whether venousinert gas lung embolization after diving simulation is a modelof pulmonary embolism.Methods Twelve recreational divers underwent two single aircompressions, each in different post-compression posture, in thechamber to 30 m/40 min bottom time with standard decompressionand ascent rates. Cardiopulmonary variables and precordialbubble grade were measured in sitting or lying supine before and40, 70 and 100 min after the respective compression.Results The volume of airways decreased post-compression in supine(24%, p<0.01), as well as in sitting posture (28%, p<0.05).As a sign of lung embolization, the alveolar dead space increasedsignificantly only in supine posture (from 27 to 65 mL, p<0.05).Transcutaneous arterial oxygen tension decreased post-compressionfrom 11,8 to 9,5 kPa in supine posture (p<0.01) and from 11,3to 9,72 kPa in sitting posture (p<0.005). Minute ventilation andbreathing frequency increased significantly only in sitting posture.Cardiovascular depression was suggested from reductions in systolicblood pressure (both postures), heart rate and pulse pressure(sitting posture) and from apparent, but not significant decreasesin cardiac output (both postures). Most of the signs were most pronouncedat 40 minutes post-compression and persisted at 100 minpost-compression.Conclusion Small, transient post-compression lung embolizationby inert gas bubbles induces some of the cardiopulmonary signsof pulmonary embolism, especially if the diver is lying after thecompression.
