The Forensic Pathology of Drowning and Pulmonary Overexpansion Injury

Abstract

Drowning deaths are commonly seen in most forensic pathology practices. Experienced forensic pathologists perform autopsies and assign a cause and manner of death in such cases as a matter of routine. Deaths due to pulmonary overexpansion injury and subsequent air embolism are far less common and typically involve individuals who have been breathing compressed gas at depth, generally SCUBA (self-contained underwater breathing apparatus) divers. This review outlines the pathophysiological basis of these two forensic pulmonary issues and recommends an approach to performing and interpreting the results of a forensic autopsy when faced with such cases.

Pulmonary barotrauma in SCUBA diving-related fatalities: a histological and histomorphometric analysis

“…PBt/AGE is one of the most serious diving accidents that can occur during SCUBA diving ascent if the breath is held and retained inside the lungs while environmental pressure is reduced. Some authorities describe or refer to this as parenchymal haemorrhage, segmental or lobe rupture and even lung bursts [ 9 , 14 , 39 ]. In our series of autopsies, only one case of alveolar haemorrhage was identified.…”

“…Currently, different terms have been used to refer to a PBt. These include pulmonary overexpansion injury, pulmonary over-inflation syndrome, extra-alveolar air syndrome and intrathoracic hypopressive syndrome [ 9 , 11 – 13 ]. However, each of these diagnoses has different clinical manifestations such as subcutaneous emphysema, pneumomediastinum, pneumothorax, pneumoperitoneum or AGE, including the death of the diver within minutes [ 8 , 9 , 14 – 16 ].…”

“…Although drowning is the main cause of death, arterial gas embolism following pulmonary barotrauma (PBt/AGE) during exposure to reduced environmental pressure (PBt of ascent) has been described in 13–24% of cases [ 17 , 18 ], and this is well documented in diving medical texts [ 2 , 9 , 19 – 21 ]. According to Boyle’s law, when a SCUBA diver ascends to the surface too quickly without exhaling appropriately, the gas retained in their lungs increases the intrapulmonary pressure while external pressure decreases rapidly [ 12 , 14 , 15 , 22 , 23 ].…”

“…This increase in intrapulmonary lung tension results in a pulmonary histopathological pattern characterized by over-distension of the air spaces (AS) distal to the terminal bronchiole and this leads to bronchoalveolar emphysema with rupture of the alveolar air sacs. Therefore, gas is then introduced into the blood vessels which are no longer intact [ 8 , 9 , 13 , 24 ]. Currently, it is agreed that alveolar tears could provide the avenue for entrance of air into the stroma of the lung.…”