Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines.

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3 h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1ß (IL-1ß), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

Nrf2 protects against seawater drowning-induced acute lung injury via inhibiting ferroptosis.

BACKGROUND: Ferroptosis is a new type of nonapoptotic cell death model that was closely related to reactive oxygen species (ROS) accumulation. Seawater drowning-induced acute lung injury (ALI) which is caused by severe oxidative stress injury, has been a major cause of accidental death worldwide. The latest evidences indicate nuclear factor (erythroid-derived 2)-like 2 (Nrf2) suppress ferroptosis and maintain cellular redox balance. Here, we test the hypothesis that activation of Nrf2 pathway attenuates seawater drowning-induced ALI via inhibiting ferroptosis. METHODS: we performed studies using Nrf2-specific agonist (dimethyl fumarate), Nrf2 inhibitor (ML385), Nrf2-knockout mice and ferroptosis inhibitor (Ferrostatin-1) to investigate the potential roles of Nrf2 on seawater drowning-induced ALI and the underlying mechanisms. RESULTS: Our data shows that Nrf2 activator dimethyl fumarate could increase cell viability, reduced the levels of intracellular ROS and lipid ROS, prevented glutathione depletion and lipid peroxide accumulation, increased FTH1 and GPX4 mRNA expression, and maintained mitochondrial membrane potential in MLE-12 cells. However, ML385 promoted cell death and lipid ROS production in MLE-12 cells. Furthermore, the lung injury became more aggravated in the Nrf2-knockout mice than that in WT mice after seawater drowning. CONCLUSIONS: These results suggested that Nrf2 can inhibit ferroptosis and therefore alleviate ALI induced by seawater drowning. The effectiveness of ferroptosis inhibition by Nrf2 provides a novel therapeutic target for seawater drowning-induced ALI.

Emerging concept of vitreous concentrations of proteins and lipids as discriminant of fresh water drowning death.

BACKGROUND: Drowning is the leading cause of unintentional death in the world, with about 372,000 drowning deaths reported annually. Forensic opinion of drowning is considered one of the most difficult tasks in confirming the exact cause of death. Drowning is now possibly patronized to cover up intentional crimes. This study was aimed at utilizing concentrations of vitreous proteins and lipids in making inroad into the inquest of true drowning. Twelve albino rabbits constituted the sample size. The rabbits were divided into three groups; control death (CD), post-mortem submersion death (PSD) and truly drowned death (TDD). Vitreous humor was extracted from the eyes of all the rabbits and centrifuged for biochemical analysis. The biochemical parameters analyzed included vitreous total protein (TP), albumin (ALB), globulin (GLO), albumin/globulin (A/G) ratio, immunoglobulin G (IgG), immunoglobin M (IgM) total cholesterol (TC), triacylglycerol (TG), high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL) and glucose (GLU) using standard methods. RESULT: The mean concentrations of vitreous parameters amongst the groups were compared using one-way anova (pos hoc-LSD). The findings revealed that the concentrations of vitreous TP, GLO, IgG, IgM, TG, TC, TG, HDL, VLDL and GLU were significantly elevated (p < 0.05), whereas ALB and A/G ratio decreased significantly amongst the drowned death group compared to that either CD or PSD. CONCLUSION: The findings have indicated that some vitreous protein and lipid parameters could aid in discriminating deaths that truly emanated from true drowning from that of post-mortem drowning and suffocation.

Effect of tidal volume on gas exchange during rescue ventilation.

Tidal volume VT required for mouth-to-mouth (MTM) and bag-valve-mask (BVM) rescue ventilation remains debatable owing to differences in physiology and end-point objectives. Analysis of gas transport may clarify minimum necessary VT and its determinants. Alveolar and arterial O2 and CO2 responses to MTM and air BVM ventilation for VT between 0.4 and 1.2 liters were computed using a model of gas exchange that incorporates inspired gas concentrations, airway dead space, cardiac output, pulmonary shunt, blood gas dissociation curves, tissue compartments, and metabolic rate. Parameters were adjusted to match published human data. Steady state arterial oxygen saturation reached plateaus at VT above 0.7 liters with MTM and 0.6 liters with air ventilation at 12 breaths per minute. Increasing shunt shifted oxygenation plateaus downward, but larger tidal volumes did not improve oxygen saturation. Carbon dioxide retention occurred at VT below 2.3 liters for MTM ventilation and 0.6 liters for air ventilation. Results establish a physiological foundation for tidal volume requirements during resuscitation.

Heme oxygenase-1 attenuates seawater drowning-induced acute lung injury through a reduction in inflammation and oxidative stress.

OBJECTIVE: Heme oxygenase-1 (HO-1) plays a critical protective role in various insults-induced acute lung injury (ALI) through its strong anti-inflammatory, anti-oxidant, and anti-apoptotic properties, but its protective role and mechanism on seawater aspiration-induced acute lung injury remains unclear. This study aimed to explore the therapeutic potential and mechanism of HO-1 to attenuate seawater aspiration-induced ALI in vivo and in vitro. METHODS: The viability and invasion of A549 cell were analyzed through cell counting kit-8 and lactate dehydrogenase release assay; the transcriptional level of inflammatory cytokines (TNF-α, IL-6, IL-8 and MCP-1) and cell proliferation-related cytokines (FoxM1, Ccnb1 and Cdc25C) in seawater-treated A549 cell were tested by qPCR; apoptotic cells were analyzed by flow cytometryd; HO-1mRNA and protein were determined by qPCR and western blotting; the fluorescent indicators (DCFH-DA, dihydroethidium, MitoSox Red and Fluo-4) were used to monitor generation of ROS and mitochondrial function. The lung wet/dry weight radio and lactate dehydrogenase activity, Sirius red staining, TUNEL assay and immunohistochemical staining with anti-pan Cytokeratin antibody were analyzed in seawater-drowning mice. The role of HO-1 on seawater-drowning pulmonary injury was explored via HO-1 activity inhibitors (Zinc protoporphyrin) in vitro and in vivo. RESULTS: Seawater exposure decreased the cellular viability, increased the production of pro-inflammatory cytokines (IL-6, IL-8 and TNF-α), induced cellular apoptosis and inhibited the expression of cell proliferation-related cytokines (FoxM1, Ccnb1 and Cdc25C). Moreover, seawater exposure led to mitochondrial dysfunction in A549 cells. Supplement of HO-1 sepcific inducer (heme) or its catalytic product (biliverdin) significantly attenuated seawater-induced A549 damage and promoted cell proliferation. However, Zinc protoporphyrin abolished the beneficial effects of HO-1 on seawater drowning-induced pulmonary tissue injury. CONCLUSION: HO-1 attenuates seawater drowning-induced lung injury by its anti-inflammatory, anti-oxidative, and anti-apoptosis function.

Postmortem water contents of major organs with regard to the cause of death.

The water contents of individual organs are maintained in a narrow range, but altered in morbidity owing to a disturbance of water equilibrium. The present study investigated the tissue water contents of major organs with regard to the cause of death in serial autopsy cases within 3 days postmortem (n = 329; 223 males, 106 females; age range, 1-100 years). Individual tissue water contents differed markedly across organs, but no significant postmortem or survival-period dependence, gender-related difference, or age dependence was observed. However, the lung water contents were higher in drowning cases, especially in saltwater cases (p < 0.05), and in strangulation among the acute mechanical asphyxiation cases. The brain water contents were higher in hypothermia cases (cold exposure) and tended to be higher in hyperthermia cases (heatstroke). The kidney water contents were higher in drowning and acute cardiac cases than in fatal intoxication and fire fatality cases, but tended to be higher in fresh- and bathwater drowning cases than in saltwater cases (p > 0.05). The spleen water contents were higher in bathwater drowning than in saltwater and freshwater cases, but did not differ among other the causes of death. These findings suggest that the postmortem tissue water content of individual organs, especially the lungs and/or kidney, depends on the cause of death and particularly contributes to differentiation between saltwater and freshwater drowning, respectively. This work therefore provides insight into the investigation of varied tissue water imbalances during the death process. In conclusion, we recommend the measurement of tissue water content because it is easy to perform and appears to be useful for evaluating the pathophysiology of systemic circulatory failure.

Postmortem Vitreous Humor Magnesium Does Not Elevate in Salt Water Drowning When the Immersion Time Is Less Than an Hour.

BACKGROUND: Elevation in postmortem vitreous humor sodium and chloride (PMVSC) in salt water drowning (SWD) when the immersion time is less than 1 hour (SWD1) is hypothesized to result from electrolyte changes in blood from salt water inhalation/ingestion during drowning. After approximately 1 hour after death, electrolytes may diffuse into the vitreous humor via the eye coverings. Another abundant element in salt water is magnesium, which is approximately 50 times higher in concentration than the blood and vitreous humor magnesium levels. Magnesium is able to diffuse across the eye coverings but not as easily through the blood-ocular barrier. With these properties, we hypothesize that postmortem vitreous magnesium (PMVM) would not be elevated in SWD1 but become elevated in SWD with immersion times greater than 1 hour (SWD>1). AIM: The aim of this article was to investigate the differences in PMVM and PMVSC between nonimmersion deaths, SWD1, and SWD>1. METHODS: This is a 1-year retrospective study comparing PMVM and PMVSC in nonimmersion deaths, SWD1, and SWD>1. RESULTS: Postmortem vitreous magnesium is significantly higher in SWD>1 than SWD1 and nonimmersion deaths, with no significant difference between SWD1 and nonimmersion deaths. Postmortem vitreous humor sodium chloride is statistically higher in SWD1 and SWD>1 than nonimmersion deaths. CONCLUSIONS: As a conclusion, PMVSC elevates and PMVM does not elevate in SWD1.

Metabolic recovery from drowning by insect pupae.

Many terrestrial insects live in environments that flood intermittently, and some life stages may spend days underwater without access to oxygen. We tested the hypothesis that terrestrial insects with underground pupae show respiratory adaptations for surviving anoxia and subsequently reestablishing normal patterns of respiration. Pupae of Manduca sexta were experimentally immersed in water for between 0 and 13 days. All pupae survived up to 5 days of immersion regardless of whether the water was aerated or anoxic. By contrast, fifth-instar larvae survived a maximum of 4 h of immersion. There were no effects of immersion during the pupal period on adult size and morphology. After immersion, pupae initially emitted large pulses of CO2 After a subsequent trough in CO2 emission, spiracular activity resumed and average levels of CO2 emission were then elevated for approximately 1 day in the group immersed for 1 day and for at least 2 days in the 3- and 5-day immersion treatments. Although patterns of CO2 emission were diverse, most pupae went through a period during which they emitted CO2 in a cyclic pattern with periods of 0.78-2.2 min. These high-frequency cycles are not predicted by the recent models of Förster and Hetz (2010) and Grieshaber and Terblanche (2015), and we suggest several potential ways to reconcile the models with our observations. During immersion, pupae accumulated lactate, which then declined to low levels over 12-48 h. Pupae in the 3- and 5-day immersion groups still had elevated rates of CO2 emission after 48 h, suggesting that they continued to spend energy on reestablishing homeostasis even after lactate had returned to low levels. Despite their status as terrestrial insects, pupae of M. sexta can withstand long periods of immersion and anoxia and can reestablish homeostasis subsequently.

Evaluation of procalcitonin postmortem levels in some models of death: An experimental study.

Post-mortem determination of biochemical parameters, especially for obscure cases, has been recognized useful in diagnosis of the underlying causes of death. Procalcitonin (PCT) is known to rise in a response to any proinflammatory stimulus. The present study aims to estimate postmortem PCT levels in serum and kidney, liver, brain; and whether it is similar in different causes of death models (trauma, drowning and freezing) models or not. The study was performed on 60 male rabbits. Rabbits were divided into four different death induced models (15 rabbit each): trauma, infection, drowning and freezing models. At the end of the study, all rabbits were sacrificed; blood samples, kidneys, livers and brains were collected. PCT was measured using ELISA assay. Results showed highly significant increase in PCT levels in all tested samples in different models of death. The infection induced model showed the highest levels in all tested samples compared to other groups mainly in liver; followed by trauma model and drowning model which were increased mainly in brain's samples. The least model which showed increased PCT levels was the freezing model mainly in liver samples. Post Hoc multiple comparisons test showed significant differences between groups in most of liver, brain and kidney samples, while PCT serum blood samples were significant only between trauma and infection groups. It was concluded that PCT can differentiate between sepsis and non-sepsis related deaths and that organs like liver, kidney and brain PCT levels could be an alternative to serum PCT for the diagnosis of postmortem sepsis.

Hypertonicity contributes to seawater aspiration-induced lung injury: Role of hypoxia-inducible factor 1α.

Drowning is an important public health problem, but the mechanism of acute lung injury induced by near-drowning is rarely reported. The aim of this study is to investigate the role of hypertonicity and HIF-1α in seawater aspiration-induced lung injury. Diverse solutions were used to study the effect of hypertonicity on hypoxia, inflammation, vascular leakage, edema, and HIF-1α expression in lungs of rats. The relationship between hypertonicity and hypoxia, when they induced HIF-1α, was studied and the roles of ATM, PI3K, and p38 in the course of hypertonicity inducing HIF-1α were investigated. At last, our conclusion was verified with HIF-1α inhibitor and inducer in seawater aspiration rats. The results showed that hypertonicity, but not isotonicity and hypotonicity, promoted hypoxia, inflammation, vascular leakage, edema, and HIF-1α expression in lungs. Hypertonicity not only induced HIF-1α in a time- and dose-dependent manner but also could increase HIF-1α synergistically with hypoxia in AEC. Furthermore, hypertonicity increased HIF-1α by promoting its mRNA expression through both ATM and PI3K activation and by suppressing its protein degradation through p38 activation. During hyperosmotic stress, the increased HIF-1α promoted the production of the inflammatory cytokines in NR8383 and elevated monolayer permeability through increasing VEGF in RLMVEC. In conclusion, hypertonicity induced by aspirated seawater aggravated lung injury through increasing HIF-1α which promoted inflammation and edema in lung tissues in rats.

Diagnosis of drowning by summation of sodium, potassium and chloride ion levels in pleural effusion: differentiating between freshwater and seawater drowning and application to bathtub deaths.

Although electrolyte analysis of pleural effusion at autopsy is useful for the diagnosis of water aspiration (i.e., drowning), the method of comparing each level of sodium (Na(+)), potassium (K(+)), and chloride (Cl(-)) ions does not clearly differentiate between freshwater drowning, seawater drowning, and non-drowning. Therefore, here we introduce the summation of Na(+), K(+), and Cl(-) levels, that is SUM(Na+K+Cl), as a modified diagnostic indicator. In 21 autopsy cases of freshwater drowning, 32 cases of seawater drowning, and 43 non-drowning controls (with pleural effusion), mean SUM(Na+K+Cl) differed significantly between the groups (188.8±33.2, 403.5±107.9, and 239.3±21.7 mEq/L, respectively). We defined a SUM(Na+K+Cl) cut-off value of <195.9 mEq/L as strongly suggestive of freshwater aspiration and that of >282.7 mEq/L as strongly suggestive of seawater aspiration. When these values were applied to the two drowning groups, 15 cases (71%) of freshwater drowning and 29 cases (91%) of seawater drowning were diagnosed correctly. This new approach may be more valid than previous methods in cases found >2 days after death or those with substantial pleural effusion (>100 mL). For an additional 15 bathtub deaths, mean SUM(Na+K+Cl) was 198.8±40.0 mEq/L, and in 14 of these cases (93%) the relationship between cause of death and SUM(Na+K+Cl) could be explained using this method. Forensic pathologists should not depend exclusively on chemical findings and should consider also typical pathological indicators of drowning. This new method may be useful as a supplementary diagnostic tool when used alongside consideration of the pathological findings.

3,5,4'-Tri-O-acetylresveratrol attenuates seawater aspiration-induced lung injury by inhibiting activation of nuclear factor-kappa B and hypoxia-inducible factor-1α.

Resveratrol is a phytoalexin synthesized by a wide variety of plants, which has been proven to be effective in suppressing oxidative stress and inflammation. The aim of the present study was to investigate the effect of Resveratrol's prodrug: 3,5,4'-tri-O-acetylresveratrol, on seawater drowning-induced acute lung injury (SWD-ALI). Histological changes were assessed to study lung injuries; cytokines in lung samples were monitored by ELISA to reflect inflammation; T-SOD and MDA activity were detected to examine oxidative stress in lung tissues. Besides, we also tested the expression of NF-κB and HIF-1α to probe the possible protecting mechanism of 3,5,4'-tri-O-acetylresveratrol on AWD-ALI. The results showed that pretreatment with different doses of 3,5,4'-tri-O-acetylresveratrol improved seawater-induced lung histopathologic changes, alleviated lung edema, reduced the production of inflammatory mediators including TNF-α and IL-1ß, inhibited MDA activity, and enhanced T-SOD activity, which was possibly associated with inhibition of NF-κB and HIF-1α. In conclusion, the current study demonstrated that 3,5,4'-tri-O-acetylresveratrol exhibited a protective effect on SWD-ALI by inhibiting of the inflammatory response, which may also involve the suppression of oxidative stress in lung tissues.

Seawater induces apoptosis in alveolar epithelial cells via the Fas/FasL-mediated pathway.

Our previous study showed that seawater can cause lung tissue cell apoptosis; in the present study, the immunohistochemistry and Western blot analysis results demonstrated that Fas, FasL, and cleaved caspase-8 and caspase-3 were up-regulated in the rat lungs exposed to seawater. We found that seawater-induced human lung alveolar epithelial A549 cell apoptosis was concentration and time dependent. Moreover, seawater increased the expression of Fas, FasL, and cleaved caspase-8 and caspase-3 in A549 cells. The incubation of A549 cells in the presence of FasL-neutralising antibody (NOK-2) or caspase-8 inhibitor (Z-IETD-FMK) resulted in a decrease of seawater-induced cell apoptosis. NOK-2 inhibited Fas/FasL interaction and reduced the cleavage of caspase-8 and caspase-3, and Z-IETD-FMK blocked caspase-8 and caspase-3 activation. Seawater similarly produced a significant increase in rat alveolar type II cell apoptosis and expression of Fas and cleaved caspase-8. In summary, the Fas/FasL pathway involved in alveolar epithelial cell (AEC) apoptosis could be important in the pathogenesis of seawater-induced acute lung injury (SW-ALI).

Molecular pathology of pulmonary surfactants and cytokines in drowning compared with other asphyxiation and fatal hypothermia.

Drowning involves complex fatal factors, including asphyxiation and electrolyte/osmotic disturbances, as well as hypothermia in cold water. The present study investigated the molecular pathology of pulmonary injury due to drowning, using lung specimens from forensic autopsy cases of drowning (n = 21), acute mechanical asphyxia due to neck compression and smothering (n = 24), and hypothermia (cold exposure, n = 11), as well as those of injury (n = 23), intoxication (n = 13), fire fatality (n = 18), and acute cardiac death (n = 9) for comparison. TaqMan real-time reverse transcription polymerase chain reaction was used to quantify messenger RNA (mRNA) expressions of pulmonary surfactant-associated proteins A and D (SP-A and SP-D), tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-10. SP-A and SP-D mRNA levels were lower for drowning, mechanical asphyxiation, fire fatality, and acute cardiac deaths than for hypothermia and injury. TNF-α, IL-1ß, and IL-10 mRNA levels were higher for drowning or for drowning and injury than for other groups; there was no significant difference between fire fatality, involving airway injury due to inhalation of hot/irritant gases, and other control groups. These observations suggest characteristic molecular biological patterns of pulmonary injury involving suppression of pulmonary surfactants and activation of early-phase mediators of inflammation in drowning, with high mRNA expression levels of pulmonary surfactants in fatal hypothermia; however, there was no significant difference among these markers in immunohistochemical detection, except for SP-A. These mRNA expressions can be used as markers of pulmonary injury to assist in investigations of the pathophysiology of drowning and fatal hypothermia in combination with other biochemical and biological markers.

Difference in molecular pathology of natriuretic peptides in the myocardium between acute asphyxial and cardiac deaths.

In investigating death due to mechanical asphyxiation and drowning, a cardiac attack is important for discriminating between possible causes of death and as a contributory factor in death processes; however, general pathologies involving visceral congestion are often similar. The present study compared terminal cardiac dysfunction in these fatalities using the molecular pathology of atrial and brain natriuretic peptides (ANP and BNP) in the myocardium as markers of cardiac strain. Both mechanical asphyxiation (n=27) and drowning (n=23) showed significantly lower ANP and BNP mRNA expressions in bilateral ventricular walls than sudden cardiac deaths (n=36). In addition, right atrial wall BNP mRNA expression was lower in asphyxiation; however, immunostaining did not demonstrate any difference among these fatalities. Differences among the subtypes of asphyxiation or between fresh- and saltwater drowning were insignificant. These observations suggest a difference between primary heart failure in sudden cardiac death and terminal cardiac dysfunction secondary to fatal asphyxiation or drowning.

Tanshinone IIA ameliorates seawater exposure-induced lung injury by inhibiting aquaporins (AQP) 1 and AQP5 expression in lung.

Aquaporins (AQPs), a family of transmembrane water channels, mediate physiological response to changes of fluid volume and osmolarity. It is still unknown what role of AQPs plays in seawater drowning-induced acute lung injury (ALI) and whether pharmacologic modulation of AQPs could alleviate the severity of ALI caused by seawater aspiration. In our study, the results from RT-PCR and Western blotting showed that intratracheal installation of seawater up-regulated the mRNA and protein levels of AQP1 and AQP5 in lung tissues. Furthermore, we found that treatment of tanshinone IIA (TIIA, one of the main active components from Chinese herb Danshen) significantly reduced the elevation of AQP1 and AQP5 expression induced by seawater in rats, A549 cells and primary alveolar type II cells. Treatment of TIIA also improved lung histopathologic changes and blood-gas indices, and reduced lung edema and vascular leakage. These findings demonstrated that AQP1 and AQP5 might play an important role in the development of lung edema and lung injury, and that treatment with TIIA could significantly alleviate seawater exposure-induced ALI, which was probably through the inhibition of AQP1 and AQP5 over-expression in lungs.

[The analysis of pericardial fluid in forensic practice].

Pericardial fluid is a kind of serous fluid in pericardial cavity. Because blood undergoes postmortem changes such as autolysis and putrefaction, vitreous humor is limited,cerebrospinal fluid is easily mixed with blood, pericardial fluid, on the other hand, exists in a closed cavity and can be hardly contaminated by postmortem changes, and also is easily obtained. Pericardial fluid not only plays an important role in clinic practice, but also is widely applicable in forensic practice. This paper briefly presented the properties of pericardial fluid and its clinical significance. It reviewed biochemical changes in decedents died of heart diseases, drowning and asphyxia, and explored the significance in medico-legal investigation. Moreover, application of pericardial fluid in forensic serology, forensic toxicological analysis and other fields were also discussed. Pericardial fluid analysis may provide important information for determination of the cause of death with further investigation concerning forensic applicability of pericardial fluid.

Electrolyte analysis of pleural effusion as an indicator of drowning in seawater and freshwater.

It is important for forensic pathologists to determine the diagnosis of drowning as well as the site of drowning. In a previous study, we propose that analysis of electrolytes in pleural effusion from rats may be useful for determining whether drowning has occurred in seawater or freshwater. To test this proposal, we measured the concentration of sodium, potassium and chloride ions and total protein in pleural effusion from 40 autopsy cases: 24 involving seawater drowning, 9 freshwater drowning and 7 no drowning. The concentrations of sodium and chloride ions in pleural effusion showed a significant difference between seawater drowning and freshwater drowning. The concentration of potassium ions and total protein showed no difference between each group, although they increased in proportion to the postmortem interval in cases of both seawater and freshwater drowning. These results are almost same as our previous study and, thus, the quantitative analysis of electrolytes in pleural effusion may be useful for determining whether drowning has occurred in seawater or freshwater.

A systematic review of Magnetic Resonance Imaging and Spectroscopy in brain injury after drowning.

PRIMARY OBJECTIVE: To report Magnetic Resonance Imaging (MRI) and/or Magnetic Resonance Spectroscopy (MRS) findings in subjects with hypoxic encephalopathy caused by drowning in recent literature and to compare them with non-specific hypoxic encephalopathy. METHOD: Systematic review of the Medline Database for bibliographic citations from 1996 to 2008. RESULTS: The studies included in this review described a total of 68 victims of drowning. From those, 58 performed MRS with a decrease of N-Acetyl-Aspartate/Creatine ratio in 75.86% (n = 44), and presence of lactate in 65.52% (n = 38) of the cases. MRI data was available in 46 cases. The main finding was brain edema in 78.26% (n = 36) and abnormalities of MRI signal in basal ganglia in 75% (n = 27) of the cases. Worse clinical outcomes were reported in conjunction with degree of MRI and MRS alterations. The findings were more consistent in the latter. Comparing these results with literature from non-specific hypoxic brain injury, the drowning process is apparently more variable. CONCLUSIONS: We found a trend to a more variable pattern of brain injury as seen by MRI/MRS in victims of drowning, which may reflect the nature of the aggression. Possibly there are different mechanisms involved in aquatic submersion, such as temperature, not present in pure hypoxic injury.

[Differences between seawater- and freshwater-induced lung injuries].

OBJECTIVE: To investigate the differences between the lung injuries induced by seawater and freshwater drowning in a rabbit model. METHODS: Forty-two New Zealand rabbits were divided randomly into three groups: control group (C, n = 18), freshwater drowning group (F, n = 12), seawater drowning group (S, n = 12). The drowning model was established by pouring seawater or freshwater (2 ml/kg) into the respiratory tract through a tracheal catheter. Mean arterial pressure (MAP) and heart rate (HR) were monitored continually. Respiratory rate (RR), blood gas analysis and electrolyte contents of every rabbit were observed at different time. The lung wet to dry weight (W/D) ratio and lung permeability index (LPI) were calculated. The contents of malondialdehyde (MDA), myeloperoxidase (MPO) and superoxide dismutase (SOD) were measured by biochemical method. The expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) were detected by enzyme linked immunosorbent assay (ELISA). At the same time, the changes in pathology were studied with by hematoxylin eosin (HE) staining, and lung pathologic score (LPS) was calculated. RESULTS: There was no significant difference in blood electrolyte contents and HR among the three groups (all P > 0.05). In freshwater drowning, there was a temporary increase of MAP at 5 minutes, RR increased immediately, and partial pressure of carbon dioxide in artery (PaCO(2)) and base excess (BE) were persistently decreased (P < 0.05 or P < 0.01). Oxygenation index (PaO(2)/FiO(2)) fell to (297.8+/-81.3) mm Hg (1 mm Hg = 0.133 kPa) at 0.5 hour, then elevated to over 300 mm Hg rapidly, and then reverted to initiative level in around 2 hours. There were several edematous and petechial areas on the dependent region of the lung. Alveolar collapse and parenchymal congestion were the main pathological features. W/D ratio and LPI showed no remarkable change. In lung tissue, the level of LPS, MPO, MDA, TNF-alpha and IL-1 beta had a significant increase, while SOD had a significant decrease (P < 0.05 or P <0.01). In S group, respiratory symptoms were more serious; edematous and congestive areas of the lung were more extensive, and the dependent region showed hepatization changes. W/D ratio and LPI consisted of elevated significantly (all P < 0.01). The pathological characteristics were massive inflammatory cell infiltration and more serious alveolar edema. Compared with F group, the extent of up- or down-regulation of RR, MAP, PaO(2)/FiO(2), PaCO(2), BE, inflammatory media and cytokines in S group was more prominent and steady, and S 6-hour group had a higher pathological score than S 3-hour group and F group (P < 0.05 or P < 0.01). CONCLUSION: Seawater and freshwater drowning could not only injure pulmonary parenchymal cells directly, but also induce acute inflammatory reaction. Lung injury induced by seawater is severer than that by freshwater.