Clinical characteristics and prognosis analysis of 53 cases of drowning in children / 中国小儿急救医学

Objective:To summarize the clinical characteristics and first aid measures of children with drowning，and to provide scientific basis for the treatment and prevention of drowning in children.Methods:The clinical data of drowning children admitted to the Children's Medical Center of the First Affiliated Hospital of Hunan Normal University（Hunan Provincial People's Hospital）from January 2011 to December 2021 were retrospectively summarized. Baseline characteristics，prehospital emergency care and prognosis of the included children were analyzed.According to the time span, drowning children were divided into two stages, the first stage (2011-2016) and the second stage (2017-2021). According to cerebral performance category assessment scale,drowning children with cardiac arrest were divided into two groups: a group with good neurological prognosis and a group with poor neurological prognosis. The baseline characteristics,pre-hospital emergency care, and prognosis of drowning children during different periods and with different prognosis were analyzed.Results:A total of 53 children were enrolled during the study period，with 24 cases in the first phase（2011-2016）and 29 cases in the second phase（2017-2021）.Boys accounted for 73.6%（39/53）of the cases, the age ranged from 1 month and 24 days to 14 years old，with 1-4 years old being the most common，accounting for 58.5%（31/53）, and the season in which drowning occurred was more common in the summer（39.6%, 21/53）.Six cases (11.3%) had significant neurological sequelae, and the mortality rate was 3.8%（2/53）.There was a decrease in the proportion of drowning with water control in the second stage compared to the first stage（37.5% vs. 13.79%, P=0.046）.Thirty-two（60.4%）children experienced on-site cardiopulmonary resuscitation(CPR) after drowning，with 24 cases in the group with good neurological prognosis and 8 cases in the group with poor neurological prognosis.Children in the poor neurological prognosis group required CPR for a long duration [10.00（1.50, 25.00）min]，had lower body temperature，Glasgow Coma Score，pH and higher blood glucose levels on admission（all P < 0.05）. Conclusion:Drowning is most common in preschool children，common in boys，and drowning prevention measures for young children deserve focused attention. Children found to be in cardiac arrest at the time of drowning have a long duration of drowning and CPR，which predicts a poor neurological prognosis，and timely and effective on-site CPR is the key to reducing the drowning rate.

Application of high flow nasal canula in patients with pulmonary edema caused by seawater drowning / 中华危重病急救医学

Objective:To investigate the therapeutic effect of high-flow nasal cannula oxygen therapy (HFNC) and non-invasive positive pressure ventilation (NPPV) on patients with pulmonary edema caused by seawater drowning.Methods:A retrospective analysis method was used. Based on the Utstein database of emergency drowning in the First Hospital of Qinhuangdao, the clinical data of patients with seawater drowning pulmonary edema admitted to the emergency medicine department of the First Hospital of Qinhuangdao from January 1, 2019 to December 31, 2022 were collected. The patients were divided into NPPV group and HFNC group according to different ventilation methods. The general data, endotracheal intubation rate in 7 days, arterial blood gas analysis indexes [arterial partial pressure of oxygen (PaO 2), arterial partial pressure of carbon dioxide (PaCO 2), arterial oxygen saturation (SaO 2)] and hemodynamic indexes (systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, blood lactic acid) before and after treatment, length of stay in intensive care unit (ICU), oxygen therapy comfort of the two groups were compared. Results:A total of 54 patients were enrolled, including 21 patients in the NPPV group and 33 patients in the HFNC group. There were no significant differences in gender, age, state of consciousness and other general information between the two groups. Compared with NPPV group, the rate of endotracheal intubation in HFNC group within 7 days was significantly lower [24.2% (8/33) vs. 33.3% (7/21), P < 0.05]. Before treatment, there were no significant differences in arterial blood gas analysis and hemodynamics between the two groups. After treatment, the above indexes in both groups were significantly improved compared with those before treatment, and PaO 2, SaO 2, systolic blood pressure, diastolic blood pressure and mean arterial pressure in HFNC group were significantly higher than those in NPPV group [PaO 2 (mmHg, 1 mmHg≈0.133kPa): 93.56±6.37 vs. 82.14±6.25, SaO 2: 1.02±0.09 vs. 0.95±0.11, systolic blood pressure (mmHg): 117.37±8.43 vs. 110.42±8.38, diastolic blood pressure (mmHg): 79.43±7.61 vs. 72.21±4.32, mean arterial pressure (mmHg): 92.34±6.32 vs. 85.12±5.38], PaCO 2, heart rate and blood lactic acid were significantly lower than those in NPPV group [PaCO 2 (mmHg) : 34.26±5.63 vs. 37.24±6.22, heart rate (times/min): 73.38±7.56 vs. 86.25±5.41, blood lactic acid (mmol/L): 1.38±0.36 vs. 2.25±1.14], and the differences were statistically significant (all P < 0.05). In addition, the length of ICU stay in HFNC group was significantly shorter than that in NPPV group (days: 13.30±2.38 vs. 16.27±4.26), and the comfort rate of oxygen therapy was significantly higher than that in NPPV group [66.7% (22/33) vs. 42.8% (9/21)], with statistical significance (all P < 0.05). Conclusion:HFNC can improve the oxygenation of patients with pulmonary edema caused by seawater drowning, improve hemodynamics, reduce the rate of tracheal intubation, shorten the length of ICU stay, and improve the comfort of oxygen therapy, which has certain clinical application value.

Enzymatic Digestion Method Coupled with Artificial Intelligence Techniques in Forensic Drowning Diatom Detection / 中山大学学报(医学科学版)

ObjectiveArtificial intelligence （AI） full smear automated diatom detection technology can perform forensic pathology drowning diatom detection more quickly and efficiently than human experts.However， this technique was only used in conjunction with the strong acid digestion method， which has a low extraction rate of diatoms. In this study， we propose to use the more efficient proteinase K tissue digestion method （hereinafter referred to as enzyme digestion method） as a diatom extraction method to investigate the generalization ability and feasibility of this technique in other diatom extraction methods. MethodsLung tissues from 6 drowned cadavers were collected for proteinase K ablation and made into smears， and the smears were digitized using the digital image matrix cutting method and a diatom and background database was established accordingly.The data set was divided into training set， validation set and test set in the ratio of 3：1：1， and the convolutional neural network （CNN） models were trained， internally validated， and externally tested on the basis of ImageNet pre-training. ResultsThe results showed that the accuracy rate of the external test of the best model was 97.65 %， and the area where the model features were extracted was the area where the diatoms were located. The best CNN model in practice had a precision of more than 80 % for diatom detection of drowned corpses. ConclusionIt is shown that the AI automated diatom detection technique based on CNN model and enzymatic digestion method in combination can efficiently identify diatoms and can be used as an auxiliary method for diatom detection in drowning identification.

Clinical and epidemiological aspects of victims of maritime accidents on the Mar Grande-Salvador crossing, Bahia, Brazil: a case series study

ABSTRACT BACKGROUND: Maritime transportation is an activity of vital importance for societies. The Mar Grande-Salvador crossing is an intercity waterway transport line in Brazil that transports 3,500 passengers/day, including residents and tourists. In 2017, an accident on this crossing was considered to be the biggest maritime tragedy in Bahia in the last decade. OBJECTIVE: To describe the clinical and epidemiology characteristics of victims of this maritime accident, with analysis on bodily injuries, causes of death and means/instruments that caused the fatal injuries. DESIGN AND SETTING: Case-series study at the Forensic Medical Institute of Bahia, Brazil. METHODS: Reports on 73 victims who were examined for bodily injury or were necropsied by the Forensic Medical Institute were analyzed. This study was approved by the institution's Research Ethics Committee (protocol 04012218.1.0000.5032). RESULTS: The victims' mean age was 33.0 years [95% confidence interval, CI, 26.3-47.0]. The mean age of those who died was 43.0 years [95% CI, 30.5-53.5]. Bodily injuries were found in 74% of the victims. The most frequent bodily injuries were ecchymoses among females (69.7%) and abrasions among males (76.2%). Blunt instruments produced most bodily injuries (85.2%). Among the victims who died, 68.4% were female. Mechanical asphyxiation through drowning was the leading cause of death (89.4%). The overall lethality rate was 26%, and this was higher among females (28.2%). CONCLUSION: Women were the main victims of this maritime accident. Bodily injuries occurred more frequently than death, but these injuries proved to be quite significant, thus demonstrating the importance of measures to improve the safety of navigation.

Clinical and microbiological characteristics of children with drowning-associated aspiration pneumonia / 中国当代儿科杂志

OBJECTIVES@#To study the clinical and microbiological characteristics of children with drowning-associated aspiration pneumonia, so as to provide a reference for empirical selection of antibacterial agents.@*METHODS@#A retrospective analysis was performed on the medical data of 185 children with drowning-associated aspiration pneumonia who were admitted to Children's Hospital of Chongqing Medical University from January 2010 to October 2020. According to the drowning environment, these children were divided into four groups: fecal group (n=44), freshwater group (n=69), swimming pool group (n=41), and contaminant water group (n=31). The clinical characteristics and pathogen detection results were reviewed and compared among the four groups.@*RESULTS@#The 185 children had an age of 4 months to 17 years (median 34 months). Sputum cultures were performed on 157 children, and 103 were tested positive (65.6%), with 87 strains of Gram-negative bacteria (68.5%), 37 strains of Gram-positive bacteria (29.1%), and 3 strains of fungi (2.4%). Gram-negative bacteria were the main pathogen in the fecal group and the contaminant water group, accounting for 88.2% (30/34) and 78.3% (18/23), respectively. The freshwater group had a significantly higher detection rate of Gram-positive bacteria than the fecal group (P<0.008), and the swimming pool group had an equal detection rate of Gram-negative bacteria and Gram-positive bacteria.@*CONCLUSIONS@#For pulmonary bacterial infection in children with drowning in feces or contaminant water, antibiotics against Gram-negative bacteria may be applied empirically, while for children with drowning in a swimming pool or freshwater, broad-spectrum antibiotics may be used as initial treatment, and subsequently the application of antibiotics may be adjusted according to the results of the drug sensitivity test.

Incidence, mortality and trends of drowning among children aged 0-14 years in China, 1990-2019 / 中国学校卫生

Objective@#To understand the incidence and mortality of drowning and secular trend among children aged 0-14 from 1990 to 2019 in China, so as to provide reference for drowning intervention among children in China.@*Methods@#Based on data of drowning incidence and death in 0-14 years old children in China in 1990-2019 years Global Burden of Disease (GBD 2019) database, the standardized rate was calculated by the world standard population, and the trend of incidence rate and mortality rate was fitted by Joinpoint regression model respectively.@*Results@#From 1990 to 2019, the overall incidence of drowning among children aged 0-14 years in China decreased from 37.17/100 000 to 12.54/100 000, a relative decrease of 66.26%; the standardized incidence rate decreased from 21.78/100 000 to 14.98/100 000, a relative decrease of 31.22%. The incidence rate and standardized incidence rate of drowning in children showed an increasing after decreasing trend, with decreasing mortality and standardized mortality rate. Joinpoint regression showed that the incidence rate of standardized AAPC for child drowning was -1.3, -2.5 for males and 0 for females. The overall standardized mortality rate of drowning was -3.9, male was -3.6, female was about -4.5 , the trend changes were statistically significant ( P <0.05). The incidence rate and mortality rate of male were higher than that of female, and there was significant difference between male and female groups ( P <0.05).@*Conclusion@#Significant progress has been made in child drowning prevention and control, with substantial decreasing in the incidence rate of child drowning. However, considering recent slight increase in drowning incidence, effective measures should be developmed including risk factors, vulnerable population to further control the incidence and mortality of child drowning.

Trends in mortality and life lost due to drowning in Huzhou City from 2012 to 2021 / 预防医学

Objective@#To investigate the mortality and years of life lost due to drowning in Huzhou City from 2012 to 2021, so as to provide insights into drowning prevention and control.@*Methods@#The mortality surveillance data on drowning in Huzhou City from 2012 to 2021 were collected from the Zhejiang Chronic Disease Surveillance Information Management System. The crude mortality and standardized mortality of drowning by the 2010 population census data in 2010, years of potential life lost (YPLL) and working years of potential life lost (WYPLL) due to drowning were calculated. In addition, the annual percent change (APC) was used to analyze the trends in drowning mortality and the rate of YPLL and WYPLL in Huzhou City from 2012 to 2021.@*Results@# A total of 1 681 deaths occurred due to drowning in Huzhou City from 2012 to 2021, accounting for 9.11% of total injury deaths. The overall mortality and standardized mortality of drowning were 6.35/105 and 4.70/105, respectively, and mortality and standardized mortality of drowning were 6.95/105 and 5.44/105 in men and 5.76/105 and 3.98/105 in women, respectively. The highest mortality of drowning was found in residents at ages of 65 years and older (16.04/105 to 27.02/105), followed by in residents at ages of less than 5 years (2.54/105 to 16.37/105). The overall mortality of drowning was 5.29/105 to 7.21/105 among residents in Huzhou City from 2012 to 2021, and no significant change tendency was seen (APC=-2.18%, t=-2.085, P=0.071). The standardized mortality of drowning reduced from 6.10/105 to 3.69/105 (APC=-4.88%, t=-4.215, P=0.003). In addition, the YPLL and rate of YPLL, and WYPLL and the rate of WYPLL due to drowning mortality were 22 620.50 person-years, 0.10%, 17 956.50 person-years and 0.08% in Huzhou City from 2012 to 2021, respectively, and the rates of YPLL (APC=-6.95%, t=-3.203, P=0.016) and WYPLL (APC=-7.60%, t=-3.126, P=0.014) both appeared a tendency towards a decline from 2012 to 2021. @*Conclusions@#The standardized mortality of drowning and rate of YPLL appeared a tendency towards a decline among residents living in Huzhou City from 2012 to 2021, and residents at ages of 65 years and older and less than 5 years are high-risk populations for management of drowning mortality.

Changes of cognitive function in non-fatal drowning rats after blast-induced traumatic brain injury / 中华创伤杂志

Objective:To investigate the changes of cognitive function in non-fatal drowning rats after blast-induced traumatic brain injury (bTBI).Methods:Eighty SD rats were divided into normal group, bTBI group, drowning group and bTBI plus drowning group according to the random number table, with 20 rats per group. Rats in normal group were not injured. In bTBI group, bTBI was established in a BST-I biological shock tube with a pressure of 4.0 MPa in the driving section. In drowning group, rats were subjected to non-fatal drowning by falling into the water with temperature of 18 ℃ and depth of 30 cm from the height of 1 m and were taken out quickly after swimming to exhaustion. After being injured in a biological shock tube, rats in bTBI plus drowning group were immediately forced to drowning using the same method. On day 3 post-injury, the neurocognitive function was evaluated by elevated plus maze and Morris water maze tests. Morphological changes of neurons in CA1 and CA3 regions of hippocampus were observed by Nissl staining, and the number of surviving neurons were counted. The concentrations of hippocampal neurotransmitters glutamate, γ-aminobutyric acid (GABA), glycine and endoplasmic reticulum stress (ERS) related glucose-regulated protein 78 (GRP78) and caspase-12 were examined by ELISA analysis. Levels of B-cell lymphoma-2 (Bcl-2), Bcl-2 associated protein (Bax) and caspase-3 were detected by Western blotting. The ratio of Bcl-2 to Bax was calculated as well.Results:In elevated plus maze test, the percentage of open arm entry and number of head-dipping behaviour were decreased in bTBI plus drowning group compared with normal and bTBI groups at 3 days after injury ( P<0.05 or 0.01), with no statistical difference from those in drowning group ( P>0.05). The number of head-dipping behaviour in drowning group was lower than that in bTBI group ( P<0.05). In Morris water maze test, bTBI plus drowning group showed increased target latency on the third and fourth days of spatial acquisition training and decreased number of crossing the target area and percentage of swimming time in the target quadrant during probe trials as compared with normal group ( P<0.05 or 0.01), but there was no statistical difference among bTBI, drowning and normal groups (all P>0.05). Nissl staining showed that the neurons in the CA1 and CA3 regions of hippocampus in normal group were arranged neatly with clear Nissl bodies at 3 days after injury, while the other groups showed different degrees of injury. In contrast with normal group, the neurons in the CA1 and CA3 regions of hippocampus in all other groups were decreased with the lowest number in bTBI plus drowning groups ( P<0.05 or 0.01). In ELISA analysis, the level of hippocampal glutamate in bTBI plus drowning group was higher than that in all other groups at 3 days after injury and the level in bTBI injury and drowning groups was higher than that in normal group ( P<0.05 or 0.01); the level of hippocampal glycine in bTBI plus drowning group was lower than that in normal group ( P<0.05), but there was no statistical difference among bTBI, drowning or normal groups (all P>0.05); the concentration of hippocampal GABA had no statistical difference among all groups (all P>0.05). In addition, the concentration of GRP78 in bTBI injury, drowning and bTBI injury plus drowning groups were increased compared with normal group ( P<0.05 or 0.01), but did not statistically differ from each other (all P>0.05). The concentration of caspase-12 in drowning and bTBI plus drowning groups were increased compared with normal group ( P<0.05 or 0.01), but was not statistically different from each other ( P>0.05), and its concentration in bTBI plus drowning group was increased compared with bTBI group ( P<0.05). In Western blotting, the level of Bcl-2 in bTBI plus drowning group was decreased compared with all other groups at 3 days after injury, and the level in bTBI and drowning groups were decreased compared with normal group, but a much lower level was observed in drowning group than that in bTBI group ( P<0.05 or 0.01); the level of Bax in bTBI plus drowning group was increased compared with all other groups at 3 days after injury, and the level in drowning group was increased compared with normal group ( P<0.05 or 0.01), with no statistical difference between bTBI and drowning groups ( P>0.05). The ratio of Bcl-2 to Bax in bTBI plus drowning group was decreased compared with all other groups, while the ratio in bTBI and drowning groups were decreased compared with normal group, showing a much lower level in drowning group than that in bTBI group ( P<0.05 or 0.01). Also, the level of caspase-3 in drowning and bTBI plus drowning groups were increased compared with normal and bTBI groups ( P<0.05 or 0.01), but there was no statistical difference between drowning and bTBI plus drowning groups ( P>0.05). Conclusions:Non-fatal drowning can aggravate hippocampal neuron damage in bTBI rats and cause memory, emotion and other cognitive dysfunction. The mechanism may involve the imbalance of hippocampal neurotransmitters glutamate and glycine, which activates the downstream pro-apoptotic pathway through ERS in the early stage of injury to induce hippocampal neuron apoptosis.

Review and Prospect of Diagnosis of Drowning Deaths in Water / 法医学杂志

Drowning is the death caused by asphyxiation due to fluid blocking the airway. In the practice of forensic medicine, it is the key to determine whether the corpse was drowned or entered the water after death. At the same time, the drowning site inference and postmortem submersion interval (PMSI) play an important role in the investigating the identity of the deceased, narrowing the investigation scope, and solving the case. Based on diatoms testing, molecular biology, imaging and artificial intelligence and other technologies, domestic and foreign forensic scientists have done relative research in the identification of the cause of death, drowning site inference and PMSI, and achieved certain results in forensic medicine application. In order to provide a reference for future study of bodies in the water, this paper summarizes the above research contents.

Research Progress of Automatic Diatom Test by Artificial Intelligence / 法医学杂志

Diatom test is the main laboratory test method in the diagnosis of drowning in forensic medicine. It plays an important role in differentiating the antemortem drowning from the postmortem drowning and inferring drowning site. Artificial intelligence (AI) automatic diatom test is a technological innovation in forensic drowning diagnosis which is based on morphological characteristics of diatom, the application of AI algorithm to automatic identification and classification of diatom in tissues and organs. This paper discusses the morphological diatom test methods and reviews the research progress of automatic diatom recognition and classification involving AI algorithms. AI deep learning algorithm can assist diatom testing to obtain objective, accurate, and efficient qualitative and quantitative analysis results, which is expected to become a new direction of diatom testing research in the drowning of forensic medicine in the future.

Application Progress of High-Throughput Sequencing Technology in Forensic Diatom Detection / 法医学杂志

Diatom detection is an important method for identifying drowning and throwing corpses after death and inferring the drowning sites in forensic examination of corpses in water. In recent years,high-throughput sequencing technology has achieved rapid development and has been widely used in research related to diatom taxonomic investigations. This paper reviews the research status and prospects of high-throughput sequencing technology and its application in forensic diatom detection.

Comparison among Four Deep Learning Image Classification Algorithms in AI-based Diatom Test / 法医学杂志

OBJECTIVES@#To select four algorithms with relatively balanced complexity and accuracy among deep learning image classification algorithms for automatic diatom recognition, and to explore the most suitable classification algorithm for diatom recognition to provide data reference for automatic diatom testing research in forensic medicine.@*METHODS@#The "diatom" and "background" small sample size data set (20 000 images) of digestive fluid smear of corpse lung tissue in water were built to train, validate and test four convolutional neural network (CNN) models, including VGG16, ResNet50, InceptionV3 and Inception-ResNet-V2. The receiver operating characteristic curve (ROC) of subjects and confusion matrixes were drawn, recall rate, precision rate, specificity, accuracy rate and F1 score were calculated, and the performance of each model was systematically evaluated.@*RESULTS@#The InceptionV3 model achieved much better results than the other three models with a balanced recall rate of 89.80%, a precision rate of 92.58%. The VGG16 and Inception-ResNet-V2 had similar diatom recognition performance. Although the performance of diatom recall and precision detection could not be balanced, the recognition ability was acceptable. ResNet50 had the lowest diatom recognition performance, with a recall rate of 55.35%. In terms of feature extraction, the four models all extracted the features of diatom and background and mainly focused on diatom region as the main identification basis.@*CONCLUSIONS@#Including the Inception-dependent model, which has stronger directivity and targeting in feature extraction of diatom. The InceptionV3 achieved the best performance on diatom identification and feature extraction compared to the other three models. The InceptionV3 is more suitable for daily forensic diatom examination.

Evaluation of Inspection Efficiency of Diatom Artificial Intelligence Search System Based on Scanning Electron Microscope / 法医学杂志

OBJECTIVES@#To explore the application values of diatom artificial intelligence (AI) search system in the diagnosis of drowning.@*METHODS@#The liver and kidney tissues of 12 drowned corpses were taken and were performed with the diatom test, the view images were obtained by scanning electron microscopy (SEM). Diatom detection and forensic expert manual identification were carried out under the thresholds of 0.5, 0.7 and 0.9 of the diatom AI search system, respectively. Diatom recall rate, precision rate and image exclusion rate were used to detect and compare the efficiency of diatom AI search system.@*RESULTS@#There was no statistical difference between the number of diatoms detected in the target marked by the diatom AI search system and the number of diatoms identified manually (P>0.05); the recall rates of the diatom AI search system were statistically different under different thresholds (P<0.05); the precision rates of the diatom AI system were statistically different under different thresholds(P<0.05), and the highest precision rate was 53.15%; the image exclusion rates of the diatom AI search system were statistically different under different thresholds (P<0.05), and the highest image exclusion rate was 99.72%. For the same sample, the time taken by the diatom AI search system to identify diatoms was only 1/7 of that of manual identification.@*CONCLUSIONS@#Diatom AI search system has a good application prospect in drowning cases. Its automatic diatom search ability is equal to that of experienced forensic experts, and it can greatly reduce the workload of manual observation of images.

Virtual Autopsy Morphological Features of Drowning / 法医学杂志

OBJECTIVES@#To explore the application value of virtual autopsy to obtain key evidence information on drowned corpses and its application value of virtual autopsy in the diagnosis of drowning.@*METHODS@#In this study, 7 corpses were selected as the research objects. The image data of corpses were collected by computed tomography (CT) before conventional autopsy. The characteristics of corpses were observed through image reading, combined with virtual measurement indexes, and compared with 15 non-drowned corpses.@*RESULTS@#The postmortem CT of drowning showed the more fluid in respiratory tract than the non-drowning, and ground-glass opacities in the lung. The statistical volume of fluid in the sinus (maxillary sinus and sphenoid sinus) was (10.24±4.70) mL in drowning cases and (2.02±2.45) mL in non-drowning cases. The average CT value of fluid in the sinus, left atrial blood and gastric contents in drowning cases were (15.91±17.20), (52.57±9.24) and (10.33±12.81) HU, respectively, which were lower than those in non-drowning cases (P<0.05).@*CONCLUSIONS@#The comprehensive consideration of multiple characteristic image manifestations and the virtual measurement indexes are helpful to the forensic pathological diagnosis of drowning. Virtual autopsy can be used as an auxiliary method in the forensic diagnosis of drowning.

Pathway of Diatoms Enter Experimental Rabbits through the Lymphatic System of the Digestive Tract / 法医学杂志

OBJECTIVES@#To study whether diatoms can enter the body through the lymphatic system of the digestive tract.@*METHODS@#Twenty experimental rabbits were divided into the test group and the control group randomly, and intragastric administration was performed with 20 mL water sample from the Pearl River and 20 mL ultrapure water, respectively. After 30 min, lymph, lungs, livers and kidneys were extracted for the diatom test. The concentration, size and type of diatoms were recorded.@*RESULTS@#The concentration of diatoms of the test group was higher than that of the control group (P<0.05). In the test group, Stephanodiscus, Coscinodiscus, Cyclotella, Melosira, Nitzschia, Synedra, Cymbella, and Navicula were detected; in the control group, Stephanodiscus, Coscinodiscus and Cyclotella were detected. The long diameter and the short diameter of diatoms of the test group were higher than those of the control group (P<0.05). In the test group, 1-2 diatoms were detected in 3 lung samples and 2 liver samples, which were Stephanodiscus or Cyclotella, and no diatoms were detected in the kidney samples; in the control group, 1-2 diatoms were detected in 2 lung samples and 3 liver samples, which were Stephanodiscus or Coscinodiscus, and no diatoms were detected in the kidney samples.@*CONCLUSIONS@#Diatoms can enter the body through the lymphatic fluid, which is one of the reasons for the presence of diatoms in tissues and organs of non-drowning cadavers.

Assisting Role of Pulmonary Hypostasis Phenomenon in Diagnosis of Drowning / 法医学杂志

OBJECTIVES@#To study the phenomenon of pulmonary hypostasis in corpses of various causes of death, and to explore the potential value of this phenomenon in assisting forensic pathological diagnosis of drowning.@*METHODS@#A total of 235 cases with clear cause of death through systematic autopsy were collected from January 2011 to June 2021 in Guangzhou. According to the location of body discovery, the cases were divided into the water body group (97 cases) and the non-water body group (138 cases), and the water body group was further divided into the water drowning group (90 cases) and the water non-drowning group (7 cases). Non-water body group was further divided into the non-water drowning group (1 case) and the non-water non-drowning group (137 cases). Three senior forensic pathologists independently reviewed autopsy photos to determine whether there was hypostasis in the lungs. The detection rate of pulmonary hypostasis was calculated.@*RESULTS@#The detection rate of pulmonary hypostasis in the water drowning group (90 cases) was 0, and the negative rate was 100%. The detection rate of pulmonary hypostasis in the water non-drowning group (7 cases) was 100% and the negative rate was 0. The detection rate of pulmonary hypostasis in the water body group and in the non-water body group (after excluding 2 cases, 136 cases were calculated) was 7.22% and 87.50%, respectively. There were statistically significant differences in the detection rate of pulmonary hypostasis between water body group and non-water body group, and between water drowning group and water non-drowning group (P<0.05).@*CONCLUSIONS@#The disappearance of pulmonary hypostasis can be used as a specific cadaveric sign to assist in the forensic pathological diagnosis of drowning.

Relationship between Water Temperature and Floating Time of Aquatic Cadavers / 法医学杂志

OBJECTIVES@#To study the relationship between water temperature and floating time of aquatic cadavers, providing a reference for more precise positioning and searching for floating corpses.@*METHODS@#The floating model of guinea pig after drowning at 17-30 ℃ was established, and the floating times of carcasses were recorded. The collected data of 32 floating corpse cases in the Pearl River were sorted out and analyzed according to the floating time of corpses corresponding to each degree of water temperature. The relationship models between water temperature and the floating time of guinea pig carcass, and between that and the floating time of real cases were established.@*RESULTS@#The floating time of the cadaver was negatively correlated with water temperature. The power function fitting equation of the relationship between floating time and water temperature of guinea pig carcass was y=1×1015x-10.530(R2=0.871, P<0.01), and the power function fitting equation of the relationship between corpse floating time and water temperature was y=3×106x-3.467(R2=0.802, P<0.01).@*CONCLUSIONS@#It is found that average floating cadaver time has a power function with water temperature, which provides a reference for locating floating cadavers and establishing search models.

Distribution of Diatoms in the Navigable Sections of Beijing-Hangzhou Grand Canal / 法医学杂志

OBJECTIVES@#To establish a diatom database by analyzing the quatity, species distribution and differences of diatom in water samples of the whole navigable sections of the Beijing-Hangzhou Grand Canal, to provide a reference for the inference of the drowning site.@*METHODS@#Water samples were collected at 22 sites in the navigable sections of the Beijing-Hangzhou Grand Canal (Jining section to Yangzhou Section), and the diatoms at each site were qualitatively and quantitatively analyzed by using graphite digestion-scanning electron microscopy.@*RESULTS@#Sampling site T (Laohuaijiang River Line, Gaoyou City, Yangzhou City, Jiangsu Province) had the highest number of diatoms, while sampling site O (Siyang County, Suqian City, Jiangsu Province) had the lowest number of diatoms, with a large gap of 68 times. At sampling site Q (Jiangpu District, Huaian city, Jiangsu Province), there were 19 species of diatoms. The sampling site O had the least diatoms, with 7 species. There were no significant differences in species evenness and species diversity at each sampling site (P>0.05). Some sampling sites have characterized diatoms, such as Caloneis at station A (Taibai Lake, Weishan County, Shandong Province), Rhoicosphenia at station B (Nanyang Town, Weishan County, Shandong Province), Amphora at station I (Taierzhuang District, Zaozhuang City, Shandong Province) and Epithemia at station J (Pizhou 310 national highway, Xuzhou City, Jiangsu Province).@*CONCLUSIONS@#The species richness of diatoms gradually increased from north to south. Diatom species richness and species diversity might be higher in areas with complex environments and large population flow. Climate type has a certain influence on the distribution of diatoms.

Change Rule of Diatom in Zhangweixin River in Dezhou / 法医学杂志

OBJECTIVES@#To study the annual variation of diatoms in Zhangweixin River, to provide theoretical support by using diatom examination to estimate the time and place of the corpse entering water, and to establish a diatom database.@*METHODS@#Samples were taken from 4 sampling sites in Decheng section of Zhangweixin River for 12 consecutive months. Non-metric multi-dimensional scaling (NMDS) analysis was performed on the species and content of diatom samples. Based on the sampling site of Tianqu Road, Sprensen similarity coefficient analysis was conducted with the data of other 3 sites in Decheng section and Leling section of Zhangweixin River and Ningjin section in previous studies.@*RESULTS@#The number of diatom species was positively correlated with diatom content. The average diatom content in different months ranged from 1 054 to 13 041/10 mL, and the species composition ranged from 8 to 16, with differences in dominant species. The similarity coefficient of diatom species within 2 km were all higher than 0.956 52, which could not be distinguished effectively. The similarity coefficients of Leling section and Ningjin section were 0.736 84 and 0.588 24 respectively, which could be effectively distinguished.@*CONCLUSIONS@#The species and content of diatom vary in different months in Zhangweixin River, and the composition of diatom species is different in different basins, which can provide reference for estimating the time and place of the corpse entering water in the river.

Bibliometrics Analysis in English and Chinese Literature on Drowning in Forensic Medicine from 1991 to 2020 / 法医学杂志

OBJECTIVES@#To explore the research hotspots and development trends of the field of forensic drowning from 1991 to 2020 by bibliometrics methods.@*METHODS@#Based on Web of Science, CNKI database, Wanfang Data knowledge service platform, python 3.9.2, CiteSpace 5.8.R3, Gephi 0.9.2, etc. were used to analyze the publishing trends, countries/regions, institutions, authors and topics of the study on drowning.@*RESULTS@#A total of 631 English literature were obtained, including 59 articles from Chinese authors, and 386 Chinese literature were obtained. The Chinese and English journals with the largest number of related literatures were Chinese Journal of Forensic Science (80 articles) and Forensic Science International (106 articles), respectively. Japan published the most articles in English, and China ranked third. Osaka City Univ (Japan, 28 articles) published the most English articles, and Guangzhou Forens Sci Inst (China, 22 articles) ranked second. Among Chinese literature, Guangzhou Forens Sci Inst (32 articles) published the most. The topic analysis of Chinese and English literature showed that diatom examination, virtual autopsy, postmortem biochemical examination, the nature of death, and postmortem submersion interval were the hot spots of current research, but English literature had more studies on new technologies and methods, while Chinese literature was more inclined to practice, application and experience summary.@*CONCLUSIONS@#The number of literature in forensic medicine on drowning is relatively stable. The scope of international and domestic collaborations in this field is still limited. The automated examination of diatoms, the establishment of diatom DNA barcodes and virtual autopsy will be the most important research hotspots in the coming period and are expected to achieve breakthroughs in drowning diagnosis, drowning location inference, postmortem submersion interval estimation, etc.