Pulmonary edema is not specific to drowning and is seen in natural (e.g., heart disease) and other unnatural deaths (e.g., acute opiate intoxication, epilepsy [4,5,8,14]). Lung findings must be correlated with circumstances (22). Voluminous or overinflated congested lungs are seen in wet drownings (6,16,138). Lungs can bulge from opened thorax, and rib markings are seen on the pleural surface. Dependent congestion suggests a postmortem finding (8). Petechiae may be seen on the visceral pleura (16). Superficial bullae (subpleural emphysema) are sometimes observed (3,16,138). Frothy fluid (edema) is expressed from the cut surface of the lungs (see Fig. 6 and ref. 16). A minimum total lung weight of 1000 g in adults (>18 yr) is significant in distinguishing between drowning and nondrowning cases; however, this cut-off weight may be arbitrary with the realization that variable amounts of water are inhaled (138,140). Other studies have shown:
• Combined weight of lungs = 1411 (avg.) ± 396.4 g in drowning; 994 ± 133.0 g in 20 controls (age >18 yr; time interval in water <24 h; controls, gunshot wound to head ).
• Combined weight of lungs = about 1400 g (avg.); 780 g in 50 controls (age >18 yr; controls, gunshot to head ).
Fig. 6. Congested lungs from drowning death. Note frothy edema fluid on cut surface of lung (arrows).
No difference in lung weights between fresh and saltwater drownings has been observed (20,22,24,138).
A minority of cases (up to 20% in 2 studies) have lung weights less than 1000 g (20,22,24,138,140). The inference is that these cases could have been dry drowning cases, but the exact circumstances are not always described (3). There is no significant correlation between submersion time and lung weights; however, 13% of witnessed non-putrified cases in a Finnish series had lung and "exudate" weights less than 1000 g compared with 35.6% of witnessed decomposed cases (3,24). Another study of recovered bodies showed a mean combined lung weight of 1439 g (range 720-2740 g) in preserved bodies and an average of 1049 g (range 380-1900 g) in severely decomposed bodies (5). The percentage of "dry" lungs (<1000 g) in nonputrefied compared with decomposed cases was 17% and 51%, respectively. A similar observation—i.e., decreased lung weights following a longer interval in the water—was made in another series (22).
The increase in the average lung weight is greater than expected in drownings compared with other types of asphyxial deaths when body recovery time is short (<6 h); however, distinguishing between drowning and asphyxiation prior to being dumped in the water, based on total lung weight, is not possible unless the lungs are severely congested (e.g., combined weight >2500 g [141 ]).
Frothy fluid, which can be blood-tinged, is seen in the larynx, trachea, and bronchi (see Heading 9; Fig. 7; and ref. 16). This is an antemortem reaction (22). Froth is an admixture of edema fluid, surfactant, and bronchial secretion (3,90). Edema fluid in freshwater drowning tends to be bloody because the hypotonic medium ruptures red
blood cells (8). In saltwater drowning, red blood cells tend to retain their integrity (8). The diagnosis of drowning may be more tenuous without the presence of froth (8). Foreign material from the drowning medium may be observed in the upper respiratory tract and lung parenchyma, but finding water or debris in the mouth or upper airway is not sufficient to diagnose drowning (Fig. 8; refs. 2, 16, 21, and 142). Froth can be seen after only a few minutes of immersion (22). Froth disappears as the postmortem interval increases (143). In one study of 1590 submersions, the presence of external foam, froth in the airways, and overlap of the medial edges of the lungs were found, respectively, in 17.3, 46.5, and 42.1% of cases submerged less than 1 d. These findings were still seen in
bodies submerged up to 1 wk, and then began to disappear (3). At 3 mo, these changes were not evident (e.g., only 4% showed overlap of lung tissue in one study ). Resuscitation obscures lung findings in drowning (e.g., emphysema, edema ).
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