Epidemiological analysis of intramuscular hemorrhage of respiratory and accessory respiratory muscles in fatal drowning cases

Abstract

The postmortem diagnosis of drowning death and understanding the mechanisms leading to drowning require a comprehensive judgment based on numerous morphological findings in order to determine the pathogenesis and epidemiological characteristics of the findings. Effortful breathing during the drowning process can result in intramuscular hemorrhage in respiratory and accessory respiratory muscles. However, the characteristics of this phenomenon have not been investigated. We analyzed the epidemiological characteristics of 145 cases diagnosed as drowning, in which hemorrhage, not due to trauma, was found in the respiratory muscles and accessory respiratory muscles. Hemorrhage was observed in 31.7% of these cases, and the incidence did not differ by gender or drowning location. The frequency of hemorrhage was significantly higher in months with a mean temperature below 20°C than in months above 20°C, suggesting a relationship between the occurrence of hemorrhage and low environmental temperature. Moreover, the frequency of hemorrhage was significantly higher in the elderly (aged ≥65 years) compared to those <65 years old. In the elderly, the weakening of muscles due to aging may contribute to the susceptibility for intramuscular hemorrhage. Moreover, these intramuscular hemorrhages do not need to be considered in cases of a potential bleeding tendency due to disease such as cirrhosis or medication such as anticoagulants. Our results indicate that intramuscular hemorrhage in respiratory and accessory respiratory muscles can serve as an additional criterion to differentiate between fatal drowning and other causes of death, as long as no cutaneous or subcutaneous hematomas above the muscles with hemorrhages are observed. In addition, the epidemiological features that such intramuscular hemorrhage is more common in cold environments and in the elderly may provide useful information for the differentiation.

Fig 1. Representative photographs of intramuscular hemorrhage in accessory respiratory muscles obtained from study samples.

(a) Sternocleidomastoid muscle of female in her late 60s. (b) Pectoralis minor muscle of male in his early 70s.

Fig 2

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) by gender. All values represent the mean ± SEM. No statistically significant differences due to gender were noted.

Fig 3

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) between victims <65 years old and ≥65 years old. All values represent the mean ± SEM. *p<0.05.

Fig 4

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) at the drowning site. All values represent the mean ± SEM.

Fig 5

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) by season. All values represent the mean ± SEM. *p<0.05.

Fig 6

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) between monthly mean temperature below 20°C and monthly mean temperature above 20°C. All values represent the mean ± SEM. *p<0.05.

Fig 7

Comparison of the frequency of intramuscular hemorrhage (a) and the number of muscles with hemorrhage (b) between victims with or without a potential bleeding tendency. All values represent the mean ± SEM. *p<0.05.