Physiology Of Drowning: A Review

Increasing ventilation in drowning resuscitation - A cross-over randomized simulation study of ventilation during automated external defibrillator analysis pauses

Objective

The aim of this study was to analyze the feasibility of a new resuscitation strategy in which breaths are provided during automated external defibrillator (AED) rhythm analysis, and to evaluate its impact on chest compressions (CC) quality and the peri-analysis time.

Method

A randomized simulation study, comparing two cardiopulmonary resuscitations strategies, has been conducted: the standard strategy (S1) with strategy involving ventilation during AED analysis (S2). Thirty lifeguards have performed both strategies in a cross-over study design during 10 min of CPR.

Results

The number of ventilations per 10 min increases from 47 (S1) to 72 (S2) (p < 0.001). This results in the delivery of an additional 17.1 L of insufflated air in S2 compared to S1 (p < 0.001). There have been no significant changes in frequency and total number of CC. These findings correspond to a reduction of the non-ventilation period from 176 s (S1) to 48 s (S2).

Conclusions

This simulation study suggests that it is feasible to increase the number of ventilations during resuscitation following drowning, without affecting the quantity and quality of chest compressions. The results of this study may serve as a foundation for further investigation into optimal ventilation strategies in this context.

A case of haemoglobinuria in a cat after near-drowning

The aim of this study is to describe a case of haemoglobinuria in a cat after near-drowning. A 6-year-old male neutered domestic short hair cat weighing 6.5 kg with a pre-existing seizure disorder presented to an emergency hospital after near-drowning in a swimming pool during a seizure episode. On presentation, the patient was obtunded, dyspnoeic, bradycardic and hypothermic. Imaging revealed evidence of severe bilateral pulmonary infiltrates. Treatment with intravenous diazepam, amoxicillin, fluid therapy, active warming and oxygen therapy was administered. The cat developed haemoglobinuria approximately 6 h after nearly drowning. Despite improvements in mentation, pulse quality and heart rate, respiratory compromise and poor oxygen saturation persisted, prompting euthanasia approximately 10 h after admission. To the author's knowledge, this is the first reported clinical case of haemoglobinuria following near-drowning in veterinary medicine.

Postmortem CT analysis of paranasal sinuses using an experimental model of drowning

Fluid-filled paranasal sinuses are suggested to be a valuable tool to distinguish between drowning and non-drowning postmortem, yet the mechanisms governing fluid entry remains unknown. We investigate if fluid-filled paranasal sinuses are caused by a passive influx from submersion or an active aspiration mechanism during drowning. The ovine nasal cavity and maxillary sinuses are remarkably similar anatomically to humans, and have been used for endoscopic surgical training in recent decades. We submerged 15 decapitated ovine heads from agricultural waste at a depth of 2 m in flowing water for 1, 8, and 24 h and 7 days. Paranasal sinuses were CT imaged and compared pre- and post-submersion to non-submerged controls. Furthermore, we examined the paranasal sinuses of a single homicide case of a non-drowned submerged subject. Results demonstrate that fluid passively enters the maxillary sinus postmortem in the non-drowned ovine heads following 1 h of submersion. Fluid volume was independent of submersion time and influenced by time out of water as well as handling, since volume was reduced between consecutive CT scans. In contrast to our hypothesis, the filling of the paranasal sinuses is due to passive influx of fluid from submersion rather than an active aspiration during drowning. The observation that paranasal sinuses were fluid-filled in a single medico-legal case of postmortem submersion supports the finding of passive influx. Consequently, careful interpretation of fluid-filled paranasal sinuses is required when bodies are found in water, as the finding cannot distinguish between postmortem submersion and drowning.

Beyond drowning: Characteristics, trends, the impact of exposure on unintentional non-drowning coastal fatalities between 2012 and 22

OBJECTIVES

Drowning has been the focus of coastal safety, but a notable proportion of coastal mortality is due to other causes of death. This study describes that burden and quantifies the impact of exposure on Australian unintentional coastal fatalities not due to drowning.

METHODS

Analyses of Australian non-drowning coastal fatalities (NDCF) between July 2012 and June 2022 were conducted. Population and exposure-based rates were calculated for Australians 16+ years and compared to all-cause mortality rates. Time series analysis was performed using Joinpoint regression.

RESULTS

616 NDCFs were recorded (0.27/100,000 pop.), with a decreasing average annual percent change of -5.1% (95% CI:-9.5 to -0.4). Cardiac conditions were the primary causal factor, involved in 52% of deaths. Higher fatality rates were seen among men and for incidents occurring in rural and remote areas. Fatality rates were disproportionately high among young adults when compared to all-cause mortality.

CONCLUSIONS

Men, young adults, and those living in/visiting regional and remote areas represent high-risk populations. Proximity to emergency services and extended response times represent major determinants of NDCF.

IMPLICATIONS FOR PUBLIC HEALTH

Due to the high prevalence of NDCF, coastal safety practitioners should expand their attention beyond drowning to consider the broader range of coastal hazards and fatality types.

Drowning and Nonfatal Drowning in Children and Adolescents: A Subsequent Retrospective Data Analysis

Fatal and nonfatal drowning are among the leading causes of death and lifelong severe neurological impairment among children and adolescents. This study aimed to complement research from Leipzig 1994-2008 to seek trends within risk factors, treatments, and outcomes throughout the last decade. We retrospectively investigated data of 47 inpatients aged 0-18 admitted to Leipzig University Department of Pediatrics who matched ICD-10 code T75.1 from 2008 to 2020 and compared them to a preceding study at the same institution. We also examined the prognostic value of parameters regarding the patients' outcomes. There were three median incidents per annum. The median age was 2.75 years; 76% of incidents happened in males. An accumulation was seen during the summer months and weekends. Most drowning incidents occurred in private ponds or pools (48.9%). Thirty-nine children were discharged without resulting morbidity, four showed neurological impairment, and three died. Risk factors concerning age, sex, and incident characteristics were confirmed. Special supervision needs still apply to 1-3-year-old male children or children with pre-existing health conditions around private pools and ponds. Hospitalization duration shortened, and morbidity and lethality decreased since the previous study. There was structural improvement in primary care and medical documentation. Parameters suggesting good outcomes include a submersion time < 5 min, GCS > 3 points, spontaneous movement upon admission, remaining pupillary light response, the absence of cardiovascular arrest, body temperature ≥ 32 °C, pH > 7, blood glucose < 15 mmol/L, lactate < 14 mmol/L, base excess ≥ -15 mmol/L, and the absence of ARDS. Clear legislation can contribute to improved private home water safety. Further studies should include a broad in- and outpatient spectrum and standardized incident documentation presupposing Utstein-style reporting. Regular reinvestigation of consistent geographical regions facilitates process evaluations of drowning epidemiology and therapy evolution.

Does adjunctive hemoadsorption provide benefit in the management of ischemia-reperfusion syndrome following near-drowning? A case report

Drowning remains a significant global health concern, claiming over 300,000 lives annually, with a disproportionate impact on young individuals in low-and middle-income countries. Conventional mechanical ventilation, while common, falls short in addressing the hypoxemia and hypercapnia often observed in severe near-drowning cases. Veno-venous extracorporeal membrane oxygenation (vvECMO) emerges as a critical intervention for cardiopulmonary failure post-drowning. This case report delves into the pivotal role of ischemia-reperfusion injury (IRI) in a near-drowning-related pathology. Following the initial insult, reoxygenation exacerbates the inflammatory cascade, resulting in a surge of pro-inflammatory mediators. In this context, CytoSorb®, a hemoadsorption cartridge, demonstrates promise by effectively removing these mediators from circulation. This report outlines its application in a critically ill adolescent patient who experienced near-drowning, presenting a compelling case for CytoSorb as an adjunctive therapy in managing IRI-induced hyperinflammation.

Transient changes in the ST-T waveform mimicking myocardial infarction in a child with near-drowning: a case report

Drowning is a common cause of childhood morbidity and mortality worldwide. Anoxia, hypothermia, and metabolic acidosis are mainly responsible for this morbidity. Drowning may lead to multiple organ damage, especially cardiac damage, in cases in which severe hypothermia and hypoxemia occur. We report a case of a 4-year-old girl who was admitted to our hospital's Emergency Department because of drowning. She had elevated troponin I concentrations and ST-segment elevation with T wave inversion. However, cardiovascular computed tomography showed no obvious abnormalities in the coronary arteries. We suggest that cardiac damage in this situation is caused by coronary artery spasms. To the best of our knowledge, this is the first case of cardiac damage with electrocardiographic changes after drowning in a preschool child.

Association between air temperature and unintentional drowning risk in the United Kingdom 2012-2019: A nationwide case-crossover study

OBJECTIVE

Drowning is a leading cause of death. The World Health Organization (WHO) and United Nations (UN) emphasise the need for population-level data-driven approaches to examine risk factors to improve water safety policies. Weather conditions, have the potential to influence drowning risk behaviours as people are more likely to spend time around water and/or undertake risky activities in aquatic spaces as a behavioural thermoregulatory response (e.g., seeking coolth).

METHODS

A case-crossover approach assessed associations between changes in daily maximum air temperature (data from the nearest weather station to each drowning event) and unintentional drowning risk using anonymous data from the validated UK Water Incident Database 2012-2019 (1945 unintentional deaths, 82% male). Control days were selected using a unidirectional time-stratified approach, whereby seven and 14 days before the hazard day were used as the controls.

RESULTS

Mean maximum air temperature on case and control days was 15.36 °C and 14.80 °C, respectively. A 1 °C increase in air temperature was associated with a 7.2% increase in unintentional drowning risk. This relationship existed for males only. Drowning risk was elevated on days where air temperature reached 15-19.9 °C (Odds Ratio; OR: 1.75), 20-24.9 °C (OR: 1.87), and ≥ 25 °C (OR: 4.67), compared with days <10 °C. The greatest elevations in risk appeared to be amongst males and when alcohol intoxication was suspected. Precipitation showed no significant association with unintentional drowning risk.

CONCLUSIONS

Identifying such relationships highlights the value of considering weather conditions when evaluating environmental risk factors for drowning, and may inform water safety policy and allocating resources to prevention and rescue.

Hypothesized mechanisms of death in swimming: a systematic review

BACKGROUND

The study aims to update the specific classification of mechanisms of death in swimming and to demonstrate these categories are reasonable, by analyzing more characteristics of death cases, evaluating the available evidence and determining their quality.

METHODS

Original articles were queried from PubMed, Web of Science, Embase databases, Cochrane Library, and Scopus. Included studies, which were evaluated as level 4 evidence or higher according to the Oxford Centre for Evidence-Based Medicine, discussed hypothesized mechanisms of death in swimming. Parameters analyzed in this study included decedents' characteristics, outcome measures, findings, methodological index for non-randomized studies (MINORS), and critical evaluation of each study classified by death mechanism.

RESULTS

A total of twenty-five studies were included for further analysis: fourteen were associated with cardiovascular diseases, two were about cerebrovascular diseases, two contained respiratory diseases, seven were about hazardous conditions and three contained other drownings, which provided evidence for mechanisms of death.

CONCLUSIONS

It is found that cardiovascular disease is the main cause or contributing factor of death in swimming. Respiratory diseases and cerebrovascular diseases are difficult to be definitive mechanism categories due to insufficient evidence. Hazardous conditions appear to be one of the possible risk factors because there are more cases of deaths from unsafe environments in swimming, but further statistics and research are still needed to support this view. Our study may have important implications for developing potential prevention strategies for sports and exercise medicine.

TRIAL REGISTRATION

PROSPERO ID (CRD42021267330). Registered Aug 13th 2021.

A quest for an integrated management system of children following a drowning incident: A review of the literature

PURPOSE

Management of children following a drowning incident is based on specific interventions which are used in the prehospital environment, the emergency department (ED) and the Paediatric Intensive Care Unit (PICU). This paper presents a review of the literature to map and describe the management and interventions used by healthcare professionals when managing a child following a drowning incident. Of specific interest was to map, synthesise and describe the management and interventions according to the different clinical domains or practice areas of healthcare professionals.

DESIGN AND METHODS

A traditional review of the literature was performed to appraise, map and describe information from 32 relevant articles. Four electronic databases were searched using search strings and the Boolean operators AND as well as OR. The included articles were all published in English between 2010 and 2022, as it comprised a timeline including current guidelines and practices necessary to describe management and interventions.

RESULTS

Concepts and phrases from the literature were used as headings to form a picture or overview of the interventions used for managing a child following a drowning incident. Information extracted from the literature was mapped under management and interventions for prehospital, the ED and the PICU and a figure was constructed to display the findings. It was evident from the literature that management and interventions are well researched, evidence-informed and discussed, but no clear arguments or examples could be found to link the interventions for integrated management from the scene of drowning through to the PICU. Cooling and/or rewarming techniques and approaches and termination of resuscitation were found to be discussed as interventions, but no evidence of integration from prehospital to the ED and beyond was found. The review also highlighted the absence of parental involvement in the management of children following a drowning incident.

PRACTICE IMPLICATIONS

Mapping the literature enables visualisation of management and interventions used for children following a drowning incident. Integration of these interventions can collaboratively be done by involving the healthcare practitioners to form a link or chain for integrated management from the scene of drowning through to the PICU.

Differences in volume, density, electrolyte concentration, and total proteins in the fluid of the paranasal sinuses of freshwater and saltwater drowning victims: a systematic review and meta-analysis

This study summarized the available evidence on the differences in volume, density, electrolyte concentration, and total proteins in paranasal sinus fluid between freshwater and saltwater drowning victims. A systematic search was conducted in electronic databases and gray literature, resulting in the inclusion of five studies with 234 drowning victims (92 saltwater incidents and 142 freshwater incidents). Meta-analyses using the inverse-of-variance method and a random-effects model were performed, reporting effect sizes as standardized mean differences (SMD) with 95% confidence intervals (CI). The findings showed a significantly higher sinus density in saltwater drowning cases compared to freshwater drowning cases (SMD 0.91, 95% CI 0.50 to 1.32). However, no significant differences were observed in sinus fluid volume. Saltwater drowning victims exhibited higher electrolyte concentrations (sodium: SMD 3.77, 95% CI 3.07 to 4.48; potassium: SMD 0.78, 95% CI 0.07 to 1.49; chloride: SMD 3.48, 95% CI 2.65 to 4.31; magnesium: SMD 4.01, 95% CI 3.00 to 5.03) and lower total protein concentrations (SMD - 1.20, 95% CI - 1.82 to - 0.58) in sinus fluid compared to freshwater drowning victims. This meta-analysis highlights the importance of analyzing the characteristics and composition of sinus fluid in forensic investigations of drowning cases. While no differences were found in sinus fluid volume, saltwater drowning victims exhibited higher sinus density, elevated electrolyte concentrations, and lower total protein concentrations compared to freshwater drowning victims.

2023 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

The International Liaison Committee on Resuscitation engages in a continuous review of new, peer-reviewed, published cardiopulmonary resuscitation and first aid science. Draft Consensus on Science With Treatment Recommendations are posted online throughout the year, and this annual summary provides more concise versions of the final Consensus on Science With Treatment Recommendations from all task forces for the year. Topics addressed by systematic reviews this year include resuscitation of cardiac arrest from drowning, extracorporeal cardiopulmonary resuscitation for adults and children, calcium during cardiac arrest, double sequential defibrillation, neuroprognostication after cardiac arrest for adults and children, maintaining normal temperature after preterm birth, heart rate monitoring methods for diagnostics in neonates, detection of exhaled carbon dioxide in neonates, family presence during resuscitation of adults, and a stepwise approach to resuscitation skills training. Members from 6 International Liaison Committee on Resuscitation task forces have assessed, discussed, and debated the quality of the evidence, using Grading of Recommendations Assessment, Development, and Evaluation criteria, and their statements include consensus treatment recommendations. Insights into the deliberations of the task forces are provided in the Justification and Evidence-to-Decision Framework Highlights sections. In addition, the task forces list priority knowledge gaps for further research. Additional topics are addressed with scoping reviews and evidence updates.

Cardiovascular and mood responses to an acute bout of cold water immersion

Cold water immersion (CWI) may provide benefits for physical and mental health. Our purpose was to investigate the effects of an acute bout of CWI on vascular shear stress and affect (positive and negative). Sixteen healthy adults (age: 23 ± 4 y; (9 self-reported men and 7 self-reported women) completed one 15-min bout of CWI (10 °C). Self-reported affect (positive and negative) was assessed at pre-CWI (Pre), 30-min post-immersion, and 180-min post-immersion in all participants. Brachial artery diameter and blood velocity were measured (Doppler ultrasound) at Pre, after 1-min and 15-min of CWI, and 30-min post-immersion (n = 8). Total, antegrade, and retrograde shear stress, oscillatory shear index (OSI), and forearm vascular conductance (FVC) were calculated. Venous blood samples were collected at Pre, after 1-min and 15-min of CWI, 30-min post-immersion, and 180-min post-immersion (n = 8) to quantify serum β-endorphins and cortisol. Data were analyzed using a one-way ANOVA with Fisher's least significance difference and compared to Pre. Positive affect did not change (ANOVA p = 0.450) but negative affect was lower at 180-min post-immersion (p < 0.001). FVC was reduced at 15-min of CWI and 30-min post-immersion (p < 0.020). Total and antegrade shear and OSI were reduced at 30-min post-immersion (p < 0.040) but there were no differences in retrograde shear (ANOVA p = 0.134). β-endorphins did not change throughout the trial (ANOVA p = 0.321). Cortisol was lower at 180-min post-immersion (p = 0.014). An acute bout of CWI minimally affects shear stress patterns but may benefit mental health by reducing negative feelings and cortisol levels.

Outcomes of patients admitted for drowning

According to the latest Utstein-style consensus, drowning is defined as the primary respiratory impairment resulting from submersion or immersion in a liquid medium.1 Patients may experience hypothermia, acute respiratory distress syndrome and shock.1 The pathophysiology is poorly understood, but could relate to physiological responses to temperature, water swallowing and electrolyte disturbances.2 Globally, more than 500,000 deaths from drowning are reported every year.3 Poor prognostic factors include low Glasgow Coma Scale (GCS) score and cardiorespiratory arrest. Treatment is largely supportive. Most preventative measures are centred on aquatic safety education and swimming lessons. Based on the National Sport Participation Survey 2018–2022, swimming has consistently ranked among the 5 most popular sports in Singapore.4 This study aimed to describe the outcomes of patients admitted for drowning.

[Ice Swimming]

Ice Swimming Abstract: Just a few years ago, no one could imagine that ice swimming could evolve into a competitive sport. In the past, people swimming in ice-cold water were called madmen and, at best, were studied as scientific objects. Today regular competitions in ice swimming over different distances (ice mile, ice km, and shorter distances such as 50m, 100m, and 200m), and different disciplines are organized (freestyle, breaststroke, backstroke, butterfly). National championships, as well as continental and world championships, are also held, with new records set regularly. In this overview, we summarize the historical development of ice swimming up to a competitive sport and explore the risks in this nascent sports discipline.

Noncardiogenic pulmonary edema in small animals

OBJECTIVE

To review various types of noncardiogenic pulmonary edema (NCPE) in cats and dogs.

ETIOLOGY

NCPE is an abnormal fluid accumulation in the lung interstitium or alveoli that is not caused by cardiogenic causes or fluid overload. It can be due to changes in vascular permeability, hydrostatic pressure in the pulmonary vasculature, or a combination thereof. Possible causes include inflammatory states within the lung or in remote tissues (acute respiratory distress syndrome [ARDS]), airway obstruction (post-obstructive pulmonary edema), neurologic disease such as head trauma or seizures (neurogenic pulmonary edema), electrocution, after re-expansion of a collapsed lung or after drowning.

DIAGNOSIS

Diagnosis of NCPE is generally based on history, physical examination, and diagnostic imaging. Radiographic findings suggestive of NCPE are interstitial to alveolar pulmonary opacities in the absence of signs of left-sided congestive heart failure or fluid overload such as cardiomegaly or congested pulmonary veins. Computed tomography and edema fluid analysis may aid in the diagnosis, while some forms of NCPE require additional findings to reach a diagnosis.

THERAPY

The goal of therapy for all types of NCPE is to preserve tissue oxygenation and reduce the work of breathing. This may be achieved by removing the inciting cause (eg, airway obstruction) and cage rest in mild cases and supplemental oxygen in moderate cases and may require mechanical ventilation in severe cases.

PROGNOSIS

Prognosis is generally good for most causes of veterinary NCPE except for ARDS, although data are scarce for some etiologies of NCPE.

Addressing gaps in our understanding of the drowning patient: a protocol for the retrospective development of an Utstein style database and multicentre collaboration

INTRODUCTION

This retrospective observational study aims to create a comprehensive database of the circumstances of drowning (including care provided and outcomes of care) to report against the Utstein style for drowning (USFD) for patients presenting to the emergency department (ED). Four areas will be examined: a feasibility study of the USFD; a comparison of classification and prognostication systems; examination of indications and efficacy of different ventilation strategies; and differences in the circumstances, severity, treatment and outcomes of drowning by sex and gender.

METHODS AND ANALYSIS

This protocol outlines retrospective data collection for all patients presenting to EDs of the Sunshine Coast Hospital and Health Service in Queensland, Australia with the presenting problem or discharge diagnosis of drowning or immersion between 2015 and 2022. Patients computerised health records (emergency medical service record, pathology, radiology results, medical and nursing notes for ED, inpatient units and intensive care units) will be used to extract data for entry into an USFD database. Descriptive (eg, median, IQR) and inferential statistical analyses (eg, analysis of variance) will be used to answer the separate research questions. Development of an International Drowning Registry using the USFD dataset and the Research Electronic Data Capture (REDCap) web application is discussed.

ETHICS AND DISSEMINATION

This study has been approved by Metro North Human Research and Ethics Committee (Project No: 49754) and James Cook University Human Research Ethics Committee (H8014). It has been endorsed by national drowning prevention organisations Royal Life Saving Society Australia (RLSSA) and Surf Life Saving Australia (SLSA). Study findings will provide data to better inform clinical management of drowning patients and provide an evidence base on sex and gender differences in drowning. Results will be disseminated through peer review publications, conference presentations and media releases. Results will also be disseminated through RLSSA and SLSA membership of the Australian and New Zealand Resuscitation Council and the Australian Water Safety Council.

Thermoregulation and thermal sensation during whole-body water immersion at different water temperatures in healthy individuals: A scoping review

BACKGROUND

Severe thermal discomfort may increase risk of drowning due to hypothermia or hyperthermia from prolonged exposure to noxious water temperatures. The importance of using a behavioral thermoregulation model with thermal sensation may predict the thermal load that the human body receives when exposed to various immersive water conditions. However, there is no thermal sensation "gold standard" model specific for water immersion. This scoping review aims to present a comprehensive overview regarding human physiological and behavioral thermoregulation during whole-body water immersion and explore the feasibility for an accepted defined sensation scale for cold and hot water immersion.

METHODS

A standard literary search was performed on PubMed, Google Scholar, and SCOPUS. The words "Water Immersion," "Thermoregulation," "Cardiovascular responses" were used either as independent searched terms and MeSH terms (Medical Subject Headings) or in combination with other text words. The inclusion criteria for clinical trials terms to thermoregulatory measurements (core or skin temperature), whole-body immersion, 18-60 years old and healthy individuals. The prementioned data were analyzed narratively to achieve the overall study objective.

RESULTS

Twenty-three published articles fulfilled the review inclusion/exclusion criteria (with nine measured behavioral responses). Our outcomes illustrated a homogenous thermal sensation in a variety of water temperatures ranges, that was strongly associated with thermal balance, and observed different thermoregulatory responses. This scoping review highlights the impact of water immersion duration on human thermoneutral zone, thermal comfort zone, and thermal sensation.

CONCLUSION

Our findings enlighten the significance of thermal sensation as a health indicator for establishing a behavioral thermal model applicable for water immersion. This scoping review provides insight for the needed development of subjective thermal model of thermal sensation in relation to human thermal physiology specific to immersive water temperature ranges within and outside the thermal neutral and comfort zone.

Effect of Vitamin C Infusion on Cerebral Oximetry During General Anesthesia for Carotid Endarterectomy in Diabetic Patients

Background

There is conflicting information about the effect of vitamin C on brain oxygenation during anesthesia.

Objectives

The current study was designed and performed to assess the effect of vitamin C infusion and brain oxygenation with cerebral oximetry on improving brain perfusion during general anesthesia in vascular surgery of diabetic patients.

Methods

This randomized clinical trial was performed on patients candidates for endarterectomy under general anesthesia and referred to Taleghani Hospital in Tehran, Iran, during 2019 - 2020. Considering inclusion criteria, the patients were divided into placebo and intervention groups. The patients in the placebo group received 500 mL of isotonic saline. In the intervention group, the patients received 1 g of vitamin C diluted in 500 mL of isotonic saline by infusion half an hour before anesthesia induction. Patients' oxygen levels were continuously measured by a cerebral oximetry sensor. The patients were put in a supine position for 10 minutes before and after anesthesia. At the end of the surgery, the indicators considered in the study were evaluated.

Results

No considerable difference was observed between systolic and diastolic blood pressure, heart rate, mean arterial pressure, partial pressure of carbon dioxide, oxygen saturation, regional oxygen saturation, supercritical carbon dioxide, and end-tidal carbon dioxide in total and between the two groups in the three stages before and after anesthesia induction and at the end of surgery (P > 0.05). Additionally, there was no significant difference between blood sugar (BS) levels in the study groups (P > 0.05) but in BS levels at three stages before and after anesthesia induction and at the end of the surgery, with a significant difference (P < 0.05).

Conclusions

The amount of perfusion in the two groups and, therefore, in total at the three stages before and after anesthesia induction and at the end of surgery is not different.

Assessing animal welfare impact of fourteen control and dispatch methods for house mouse (Mus musculus), Norway rat (Rattus norvegicus) and black rat (Rattus rattus)

Population control of the house mouse (Mus musculus), Norway rat (Rattus norvegicus) and black rat (Rattus rattus) is common practice worldwide. Our objective was to assess the impact on animal welfare of lethal and non-lethal control methods, including three dispatch methods. We used the Sharp and Saunders welfare assessment model with eight experts scoring eleven control methods and three dispatch methods used on the three species. We presumed the methods were performed as prescribed, only taking into account the effect on the target animal (and not, for example, on non-target catches). We did not assess population control efficacy of the methods. Methods considered to induce the least suffering to the target animal were captive-bolt traps, electrocution traps and cervical dislocation, while those with the greatest impact were anticoagulants, cholecalciferol and deprivation. Experts indicated considerable uncertainty regarding their evaluation of certain methods, which emphasises the need for further scientific research. In particular, the impact of hydrogen cyanide, chloralose and aluminium phosphide on animal welfare ought to be investigated. The experts also stressed the need to improve Standard Operating Procedures and to incorporate animal welfare assessments in Integrated Pest Management (IPM). The results of our study can help laypeople, professionals, regulatory agencies and legislators making well-informed decisions as to which methods to use when controlling commensal rodents.

Combining Oxidative Stress Markers and Expression of Surfactant Protein A in Lungs in the Diagnosis of Seawater Drowning

BACKGROUND AND OBJECTIVES

The diagnosis of seawater drowning (SWD) remains one of the most complex and contentious. It is one of the leading causes of unintentional death around the world. In most cases, the forensic pathologist must reach an accurate diagnosis from the autopsy findings and a series of complementary tests such as histopathological, biological, and chemical studies. Despite the lung being the most affected organ in death by submersion, there are few studies on this type of death's impact on this organ. The aim was to investigate human lung cadavers of forensic cases due to different causes of death, the concentration of the oxidative stress markers malondialdehyde (MDA) and γ-glutamyl-l-cysteinyl glycine (GSH), and the relationship with the expression of surfactant protein A (SP-A) to try to discriminate SWD from other types of causes of death.

MATERIALS AND METHODS

A total of 93 forensic autopsy cases were analyzed. Deaths were classified into three major groups based on the scene, cause of death, and autopsy findings (external foam, frothy fluid in airways, overlapping medial edges of the lungs): (a) drowning in seawater (n = 35), (b) other asphyxia (n = 33), such as hangings (n = 23), suffocations (n = 6), and strangulation (n = 4), and (c) other causes (n = 25), such as multiple suffocations. Oxidative stress markers (MDA and GSH) and the immunohistochemical expression of SP-A were determined in both lungs.

RESULTS

MDA levels were statistically higher in both lungs in cases of SWD than in other causes of death (p = 0.023). Similarly, significantly higher levels of GSH were observed in SWD compared to the rest of the deaths (p = 0.002), which was more significant in the right lung. Higher immunohistochemical expression of SP-A was obtained in the cases of SWD than in the other causes of death, with higher levels in both lungs. The correlation analysis between the levels of oxidative stress (MDA and GSH) in the lung tissue and the expression level of SP-A showed positive and significant results in SWD, both in the alveolar membrane and the alveolar space.

CONCLUSIONS

Determining the levels of MDA and GSH in lung tissue and the expression level of SP-A can be of great importance in diagnosing SWD and the circumstances of death. A better understanding of the physiology of submersion is essential for its possible repercussions in adopting measures in the approach to patients who have survived a submersion process. It is also necessary for forensic pathology to correctly interpret the events that lead to submersion.

Treating exertional heat stroke: Limited understanding of the female response to cold water immersion

According to an expansive body of research and best practice statements, whole-body cold water immersion is the gold standard treatment for exertional heat stroke. However, as this founding evidence was predominantly drawn from males, the current guidelines for treatment are being applied to women without validation. Given the recognised differences in thermal responses experienced by men and women, all-encompassing exertional heat stroke treatment advice may not effectively protect both sexes. In fact, recent evidence suggests that hyperthermic women cool faster than hyperthermic men during cold water immersion. This raises the question of whether overcooling is risked if the present guidelines are followed. The current mini-review examined the literature on women's response to cold water immersion as a treatment for exertional heat stroke and aimed to clarify whether the current guidelines have appropriately considered research investigating women. The potential implications of applying these guidelines to women were also discussed.

Post-Mortem Computed Tomography Pulmonary Findings in Harbor Porpoises (Phocoena phocoena)

Simple Summary

The use of cross-sectional imaging techniques to examine the cause of death and health status of deceased animals is increasing in both veterinary and wildlife conservation programs, including species of whales and dolphins. Lung disease is common in harbor porpoises (Phocoena phocoena), a small whale species that regularly washes up on the coast in North Sea-bordering countries. This study aimed to describe lung changes visible in computed tomographic (CT) images of recently deceased harbor porpoises before pathological dissection was performed, including comparison of these two examination methods. Despite frequently visible signs of body decomposition, several lung abnormalities (collapsed lung, fluid in the airways, lung mineralization) were more often seen on the CT images. In general, lung changes could be described in more detail compared to gross dissection. CT images of lungs of recently deceased harbor porpoises can therefore be used to guide gross dissection, leading to more specific findings and potentially a more complete understanding of the circumstances leading to the death of the porpoise, assessment of the population, and ultimately, ecosystem health.

Abstract

The application of whole-body post-mortem computed tomography (PMCT) in veterinary and wildlife post-mortem research programs is advancing. A high incidence of pulmonary pathology is reported in the harbor porpoise (Phocoena phocoena). In this study, the value of PMCT focused on pulmonary assessment is evaluated. The objectives of this study were to describe pulmonary changes as well as autolytic features detected by PMCT examination and to compare those findings with conventional necropsy. Retrospective evaluation of whole-body PMCT images of 46 relatively fresh harbor porpoises and corresponding conventional necropsy reports was carried out, with a special focus on the respiratory tract. Common pulmonary PMCT findings included: moderate (24/46) to severe (19/46) increased pulmonary soft tissue attenuation, severe parasite burden (17/46), bronchial wall thickening (30/46), and mild autolysis (26/46). Compared to conventional necropsy, PMCT more frequently identified pneumothorax (5/46 vs. none), tracheal content (26/46 vs. 7/46), and macroscopic pulmonary mineralization (23/46 vs. 11/46), and provided more information of the distribution of pulmonary changes. These results indicate that PMCT adds information on pulmonary assessment and is a promising complementary technique for necropsy, despite the frequent presence of mild autolytic features.

Epidemiology and autopsy findings of 500 drowning deaths

INTRODUCTION

Drowning is a significant public health problem worldwide and the WHO reported that drowning is the world's third leading unintentional injury death. Nevertheless, there is still uncertainty regarding the estimate of local and global drowning deaths. In addition, the postmortem diagnosis of drowning is challenging and the physiological mechanisms of death by drowning are complex and not very well understood.

PURPOSE

To analyze a large series of bodies retrieved from the water in Connecticut (U.S.) in order to compare epidemiologic and toxicological data with those of the literature, as well as to examine the weights of the lungs and brains in drowning deaths.

MATERIAL AND METHOD

We conducted a descriptive, retrospective, population-based analysis of all bodies retrieved from the water and subjected to a forensic autopsy at the Office of the Chief Medical Examiner in Connecticut (2008-2020, n = 500). Variables collected were sex, age, date of death, location of drowning, season, type of water, cause of death, manner of death, circumstances of death, signs of decomposition, BMI, brain weight, lung weight, presence of pulmonary edema, stomach contents, and toxicological analysis.

RESULTS

The death rates of drownings in Connecticut ranges from 0.75 to 1.28/100,000/year. They occurred predominantly in males (73.4%) and most were accidents (75.6%), though this gender difference diminishes in suicides (55.4% of males). Sex distribution is also different in bathtub drownings, where women drown more frequently (67.3%). Weights of the brains (p = 0.013) and lungs (p < 0.001) were higher in saltwater drownings.

CONCLUSIONS

Drowning is more frequently an accident involving men, except for suicides where there is only a slight difference among sex. Heavy lungs and cerebral edema continue to be identified in numerous drowning deaths. These anatomic findings, however, must still be interpreted in the context of the entire case investigation. Weights of the brains and lungs are higher in salt water, although these organs' weights are mostly dependent on other variables such as BMI and decomposition.

Dynamic changes of the hemoglobin index during resuscitation in patients with out-of-hospital cardiopulmonary arrest due to freshwater drowning: A retrospective observational study

Background

The hemoglobin index (HbI) represents the amount of hemoglobin, which reflects the regional tissue blood volume. The HbI is calculated by a regional oxygen saturation monitor. In freshwater drowning, inhaled water is immediately absorbed into the blood causing hemodilution. We hypothesized that this blood dilution could be observed in real time using HbI values in patients with out-of-hospital cardiac arrest (OHCA) due to freshwater drowning.

Methods

In this single-center retrospective, observational study, we examined the HbI in patients with OHCA due to freshwater drowning from April 2015 to May 2020. Patients with OHCA due to hanging were selected as a control group.

Results

Thirty-two patients in the freshwater drowning group and 21 in the control group were eligible for inclusion. In the freshwater drowning group, the HbI values in the return of spontaneous circulation (ROSC) group were significantly decreased in comparison to the non-ROSC group (-0.28 [IQR -0.55, -0.12] vs. -0.04 [IQR -0.16, 0.025]; p = 0.024). In the control group, the change of HbI during resuscitation in the ROSC and non-ROSC groups was not significantly different (0.11 [IQR -0.3525, 0.4225] vs. -0.02 [IQR -0.14, 0.605]; p = 0.8228). In each patient with ROSC in the freshwater drowning group, the HbI value after ROSC was significantly decreased in comparison to before ROSC (1.2±0.5 vs. 0.9±0.5]; p = 0.0156). In contrast, this difference was not observed in patients with an ROSC in the control group (3.7±1.3 vs. 3.8±1.4]; p = 0.7940).

Conclusion

Blood dilution induced by freshwater drowning might be detected in real time using the HbI. To prove the validity of this research's result, further prospective large study is needed.

The experience of drowning

Internationally, drowning is a leading cause of accidental death that features in many legal cases. In these cases, possible mitigations and the ‘pain and suffering’ in terms of the duration and subjective experience of drowning are often pivotal in determining levels of compensation and outcome. As a result, there is a requirement to understand the stages of the drowning process, and the duration and physiological and subjective responses associated with each stage. In this short review we focus on these issues.

The water incident database (WAID) 2012 to 2019: a systematic evaluation of the documenting of UK drownings

Background

Death by drowning is a leading cause of accidental death in the United Kingdom (UK) and worldwide. The World Health Organization (WHO) states that effective documentation of drowning is required to describe drowning frequency and to underpin effective drowning prevention intervention, thus improving the quality of data describing drowning frequency represents a key initiative. The water incident database (WAID) has been used to document UK fatal and non-fatal water-based incidents since 2009. WAID has not undergone a systematic evaluation of its data or data collection procedures to establish if the database meets the WHO requirements. The present study investigated the characteristics of UK fatal drowning incidents and audited current WAID data capture procedures.

Methods

Data for the fatal drowning cases recorded between 2012 and 2019 were reviewed. Descriptive data were generated 1) to describe fatal drownings in the UK’s WAID in this period; 2) a sub-set of drownings were audited i) for completeness of data entry and, based on source documents, ii) for quality of data entry; 3) these processes were used to make recommendations for onward revisions to WAID.

Results

A total of 5051 fatalities were recorded between 2012 and 2019. Drowning was most frequent amongst males aged 35 to 60 years (n = 1346), whilst suspected accidents and suicides accounted for 44 and 35% of fatalities. Suicide by drowning was at a peak in the most recent year of data analysed (i.e., 2019; 279 cases) highlighting an urgent need for targeted intervention. Audit part 2i) indicated that 16% of all fields were incomplete, thus indicating potential redundancy, duplication, or the need for onward review. Audit part 2ii) indicated high levels of agreement (80 ± 12%) between audited cases and the ‘true’ WAID entries.

Conclusions

This study confirms WAID as a rigorous, transparent and effective means of documenting UK drownings thereby meeting WHO requirements for data quality; yet future improvements are recommended. Such findings allow researchers and policy makers to use WAID to further investigate UK drowning with a view to improving public safety measures and drowning prevention interventions. Observations alongside several expert recommendations have informed a revised version of WAID.

Treatment of the lung injury of drowning: a systematic review

Background

Drowning is a cause of significant global mortality. The mechanism of injury involves inhalation of water, lung injury and hypoxia. This systematic review addressed the following question: In drowning patients with lung injury, what is the evidence from primary studies regarding treatment strategies and subsequent patient outcomes?

Methods

The search strategy utilised PRISMA guidelines. Databases searched were MEDLINE, EMBASE, CINAHL, Web of Science and SCOPUS. There were no restrictions on publication date or age of participants. Quality of evidence was evaluated using GRADE methodology.

Results

Forty-one papers were included. The quality of evidence was very low. Seventeen papers addressed the lung injury of drowning in their research question and 24 had less specific research questions, however included relevant outcome data. There were 21 studies regarding extra-corporeal life support, 14 papers covering the theme of ventilation strategies, 14 addressed antibiotic use, seven papers addressed steroid use and five studies investigating diuretic use. There were no clinical trials. One retrospective comparison of therapeutic strategies was found. There was insufficient evidence to make recommendations as to best practice when supplemental oxygen alone is insufficient. Mechanical ventilation is associated with barotrauma in drowning patients, but the evidence predates the practice of lung protective ventilation. There was insufficient evidence to make recommendations regarding adjuvant therapies.

Conclusions

Treating the lung injury of drowning has a limited evidentiary basis. There is an urgent need for comparative studies of therapeutic strategies in drowning.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03687-2.

The Circulatory Effects of Increased Hydrostatic Pressure Due to Immersion and Submersion

Increased hydrostatic pressure as experienced during immersion and submersion has effects on the circulation. The main effect is counteracting of gravity by buoyancy, which results in reduced extravasation of fluid. Immersion in a cold liquid leads to peripheral vasoconstriction, which centralizes the circulation. Additionally, a pressure difference usually exists between the lungs and the rest of the body, promoting pulmonary edema. However, hydrostatic pressure does not exert an external compressing force that counteracts extravasation, since the increased pressure is transmitted equally throughout all tissues immersed at the same level. Moreover, the vertical gradient of hydrostatic pressure down an immersed body part does not act as a resistance to blood flow. The occurrence of cardiovascular collapse when an immersed person is rescued from the water is not explained by removal of hydrostatic squeeze, but by sudden reinstitution of the effect of gravity in a cold and vasoplegic subject.

Lung transplantation from swimming pool drowning victims: A case series

The use of donor lungs from victims of drowning remains a rare occurrence, given concerns over lung parenchymal injury and microbial contamination secondary to aspiration. Given this infrequency, there is a relative paucity of literature surrounding the use of organs from drowned donors, with the few that exist on this subject focusing primarily on cases of drowning in naturally occurring bodies of water (i.e., drowning at sea). Little is known regarding the outcomes of utilizing donor lungs from victims of drowning in artificial bodies of water (i.e., swimming pools). Here, we describe three cases of bilateral lung transplantation from donors who drowned in swimming pools, with good short- and long-term outcomes. These cases lend further evidence to the feasibility of using such organs that have traditionally been viewed with much trepidation. With continually growing demand for donor organs, the use of drowned donor lungs may serve as a means to expand the donor pool and lessen the burden of waitlist mortality.

Trace elements in forensic human lung: A new approach to the diagnosis of seawater drowning. A preliminary study

The diagnosing of drowning remains one of the most challenging activities for the forensic pathologist. There is little information on the impact on the lung as a target organ in death by drowning. We aimed to investigate the concentration of trace elements in the lungs of people who had suffered different types of death to evaluate the discriminating ability of trace elements to identify seawater drowning (SWD). A total of 11 trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry in 74 forensic cases. Sampler scanning electron microscopy and Energy Dispersive X-ray spectroscopy (EDX) were used to identify ultrastructural lung alterations. A Principal Component Analysis (PCA) of trace elements was carried out. The trace elements in SWD lungs were detected in the following order of concentration: Br˃Zn˃Sr˃Cr˃Cu˃As˃Pb˃Se˃Mn˃Ni˃Cd. Our results showed significantly higher concentrations of Br and Sr (P = 0.010 and P = 0.000) and significantly lower concentrations of Zn, Pb, Cu, Cd, and Se in SWD compared with other causes of death. After adjusting by confounder factors, Sr and Br remained as predictive independent factors for diagnosis of drowning (p = 0.042, in both cases). These results were confirmed by PCA, which revealed a wide separation between SWD and the rest of the causes of death. Our SWD cohort was characterized by high concentrations of the trace elements Br and Sr and low concentrations of Zn, Pb, Cu, Cd, and Se in lung tissue, while PCA showed its discriminatory capacity to identify death by seawater drowning. These findings, together with those obtained using other techniques, can be of great importance in the diagnosis of SWD.

Cold Water Swimming-Benefits and Risks: A Narrative Review

Cold water swimming (winter or ice swimming) has a long tradition in northern countries. Until a few years ago, ice swimming was practiced by very few extreme athletes. For some years now, ice swimming has been held as competitions in ice-cold water (colder than 5 °C). The aim of this overview is to present the current status of benefits and risks for swimming in cold water. When cold water swimming is practiced by experienced people with good health in a regular, graded and adjusted mode, it appears to bring health benefits. However, there is a risk of death in unfamiliar people, either due to the initial neurogenic cold shock response or due to a progressive decrease in swimming efficiency or hypothermia.

Management for the Drowning Patient

Drowning is "the process of experiencing respiratory impairment from submersion or immersion in liquid." According to the World Health Organization, drowning claims the lives of > 40 people every hour of every day. Drowning involves some physiological principles and medical interventions that are unique. It occurs in a deceptively hostile environment that involves an underestimation of the dangers or an overestimation of water competency. It has been estimated that > 90% of drownings are preventable. When water is aspirated into the airways, coughing is the initial reflex response. The acute lung injury alters the exchange of oxygen in different proportions. The combined effects of fluid in the lungs, loss of surfactant, and increased capillary-alveolar permeability result in decreased lung compliance, increased right-to-left shunting in the lungs, atelectasis, and alveolitis, a noncardiogenic pulmonary edema. Salt and fresh water aspirations cause similar pathology. If the person is not rescued, aspiration continues, and hypoxemia leads to loss of consciousness and apnea in seconds to minutes. As a consequence, hypoxic cardiac arrest occurs. The decision to admit to an ICU should consider the patient's drowning severity and comorbid or premorbid conditions. Ventilation therapy should achieve an intrapulmonary shunt ≤ 20% or Pao₂:Fio₂ ≥ 250. Premature ventilatory weaning may cause the return of pulmonary edema with the need for re-intubation and an anticipation of prolonged hospital stays and further morbidity. This review includes all the essential steps from the first call to action until the best practice at the prehospital, ED, and hospitalization.

Proteomics in Deaths by Drowning: Diagnostic Efficacy of Apolipoprotein A1 and α-1Antitrypsin, Pilot Study

Drowning is one of the leading causes of death worldwide. The pathophysiology of drowning is complex and, sometimes, interpretation of the circumstances of death in the autopsy becomes the main source of information in its diagnosis. New advances in medical research, such as proteomics, especially in forensic pathology, are still in the development. We proposed to investigate the application of Mass Spectrometry-based technologies, to identify differentially expressed proteins that may act as potential biomarkers in the postmortem diagnosis of drowning. We performed a pilot proteomic experiment with the inclusion of two drowned and two control forensic cases. After applying restrictive parameters, we identified apolipoprotein A1 (ApoA1) and α-1 antitrypsin as differentially expressed between the two diagnostic groups. A validation experiment, with the determination of both proteins in 25 forensic cases (16 drowned and 9 controls) was performed, and we corroborated ApoA1 higher values in the drowning group, whereas α-1 antitrypsin showed lower levels. After adjusting by confounder factors, both remained as predictive independent factors for diagnosis of drowning (p = 0.010 and p = 0.022, respectively). We constructed ROC curves for biomarkers’ levels attending at the origin of death and established an ApoA1 cut-off point of 100 mg/dL. Correct classification based on the diagnosis criteria was reached for 73.9% of the cases in a discriminant analysis. We propose apolipoprotein A1 (with our cutoff value for correct classification) and α-1 antitrypsin as valuable biomarkers of drowning. Our study, based on forensic cases, reveals our proteomic approach as a new complementary tool in the forensic diagnosis of drowning and, perhaps, in clinical future implications in drowned patients. However, this is a pilot approach, and future studies are necessary to consolidate our promising preliminary data.

Land motor vehicle-related fatal drowning in Finland: A nation-wide population-based survey

OBJECTIVE

WHO mortality statistics overlook land motor-vehicle accident (LMVA)-related drowning. The aim of the study was to provide an overview of the prevalence and trends of fatal LMVA-related drowning in Finland, plus the main crash settings, victims' demographic characteristics, and contributing factors leading to such deaths.

METHODS

A descriptive, retrospective, population-based study of drowning deaths associated with LMVA among Finnish residents of all ages, 1971-2013. LMVA-related drownings and applicable variables were extracted from the Statistics Finland (SF) mortality database by cross-analysis of ICD injury- and external cause-of-death codes.

RESULTS

During the study period, 538 LMVAs leading to drowning occurred among Finnish residents (2.5/1 000 000/year; 4.9% of all unintentional drownings, 3.7% of all LMVA). Three main settings, ones responsible for over 95% of LMVA-related drownings, were recognized: traffic vehicle accidents involving a passenger car; non-traffic vehicle accident involving a snowmobile; and non-traffic accidents involving agricultural, industrial, or construction vehicles. Alcohol use was a contributing factor for death in > 40% of the victims, whereas severe injuries were reported in less than 6%.

CONCLUSION

Because transport safety is crucial to prevent any vehicle entering the water, placing LMVA-related drowning in the category of transport accidents is warranted. Once the vehicle becomes submersed, however, prevention measures to avoid death by drowning remains decisive.

The Mammalian Diving Response: Inroads to Its Neural Control

The mammalian diving response (DR) is a remarkable behavior that was first formally studied by Laurence Irving and Per Scholander in the late 1930s. The DR is called such because it is most prominent in marine mammals such as seals, whales, and dolphins, but nevertheless is found in all mammals studied. It consists generally of breathing cessation (apnea), a dramatic slowing of heart rate (bradycardia), and an increase in peripheral vasoconstriction. The DR is thought to conserve vital oxygen stores and thus maintain life by directing perfusion to the two organs most essential for life-the heart and the brain. The DR is important, not only for its dramatic power over autonomic function, but also because it alters normal homeostatic reflexes such as the baroreceptor reflex and respiratory chemoreceptor reflex. The neurons driving the reflex circuits for the DR are contained within the medulla and spinal cord since the response remains after the brainstem transection at the pontomedullary junction. Neuroanatomical and physiological data suggesting brainstem areas important for the apnea, bradycardia, and peripheral vasoconstriction induced by underwater submersion are reviewed. Defining the brainstem circuit for the DR may open broad avenues for understanding the mechanisms of suprabulbar control of autonomic function in general, as well as implicate its role in some clinical states. Knowledge of the proposed diving circuit should facilitate studies on elite human divers performing breath-holding dives as well as investigations on sudden infant death syndrome (SIDS), stroke, migraine headache, and arrhythmias. We have speculated that the DR is the most powerful autonomic reflex known.

Autonomic regulation of the heart and arrhythmogenesis in trained breath-hold divers

AbstractBreath-hold divers are known to develop cardiac autonomic changes and brady-arrthymias during prolonged breath-holding (BH). The effects of BH-induced hypoxemia were investigated upon both cardiac autonomic status and arrhythmogenesis by comparing breath-hold divers (BHDs) to non-divers (NDs). Eighteen participants (9 BHDs, 9 NDs) performed a maximal voluntary BH with face immersion. BHDs were asked to perform an additional BH at water surface to increase the degree of hypoxemia. Beat-to-beat changes in heart rate (HR), short-term fractal scaling exponent (DFAα1), the number of arrhythmic events [premature ventricular contractions (PVCs), premature atrial contractions (PACs)] and peripheral oxygen saturation (SpO₂) were recorded during and immediately following BH. The corrected QT-intervals (QTc) were analyzed pre- and post-acute BH. A regression-based model was used to split BH into a normoxic (NX) and a hypoxemic phase (HX). During the HX phase of BH, BHDs showed a progressive decrease in DFAα1 during BH with face immersion (p < 0.01) and BH with whole-body immersion (p < 0.01) whereas NDs did not (p > 0.05). In addition, BHDs had more arrhythmic events during the HX of BH with whole-body immersion when compared to the corresponding NX phase (5.9 ± 6.7 vs 0.4 ± 1.3; p < 0.05; respectively). The number of PVCs was negatively correlated with SpO₂ during BH with whole-body immersion (r = -0.72; p < 0.05). The hypoxemic stage of voluntary BH is concomitant with significant cardiac autonomic changes toward a synergistic sympathetic and parasympathetic stimulation. Co-activation led ultimately to increased bradycardic response and cardiac electrophysiological disturbances.

Diagnosis of Drowning and the Value of the Diatom Test in Veterinary Forensic Pathology

The detection of diatoms into the organs is considered an important “biological marker” for the diagnosis of drowning in human pathology, but it still has a high possibility for false positive results. The aims of this study were: (1) to evaluate the contribution of pathological examination in drowning cases and (2) to investigate the differences in the number and location of diatoms between animals who died in drowning and non-drowning conditions. For these purposes, 30 dead adult dogs were selected for the study and subdivided into five groups. The group A comprised six cadavers dead for drowning; the group B comprised six control animals; the groups C, D, and E comprised six animals dead for causes other than drowning and subsequently immersed in water for 24, 48, and 72 h, respectively. On each animal, a complete macroscopic and histological examination and diatom test were performed. Diatoms test and quantification were also performed on drowning mediums. Pathological findings of the animals in the group A showed pulmonary congestion, oedema, and hemorrages in the lung. However, similar injuries were also observed in control and experimentally submerged cadavers. In contrast, we observed a statistically differences between drowning animals and all experimentally submerged groups and control animals regarding diatom numbers recovered from organ tissue samples (p < 0.05). Therefore, these findings suggest that the number of diatoms may be used as a valid tool to differentiate animals who died in drowning and non-drowning conditions, even if the latter were found in an aquatic environment.

Circumstances, outcome and quality of cardiopulmonary resuscitation by lifeboat crews

BACKGROUND

Little is known regarding circumstances, outcomes and quality of cardiopulmonary resuscitation (CPR) and the use of automated external defibrillators (AEDs) performed by operational lifeboat crews. Our aim is to evaluate circumstances, outcomes and quality of CPR performed by the Royal Dutch Lifeboat Institution (KNRM) in out-of-hospital cardiac arrest (OHCA).

METHODS

The internal KNRM database has been used to identify and analyse all OHCA cases between July 2011 and December 2017. A limited set of AED data was available to study the quality of CPR.

RESULTS

In 37 patients the lifeboat crew members have performed CPR, of which 29 (78.4%) occurred under hostile conditions. The median response time to arrive at the location was 15min. In 11 (29.7%) patients return of spontaneous circulation was achieved at any moment during CPR and 3 (8.1%) patients were still alive after one month. The lifeboat AED was used in 12 patients. Their recordings show a high median compression frequency (120, IQR 111-131) and prolonged median interruption periods (pre-analysis pause 11s (IQR 10-13), post-analysis pause 4s (IQR 3-8), pre-shock pause 24s (IQR 19-26), post-shock pause 6s (IQR 6-11), ventilation pause 6s (IQR 4-8) and other pauses 9s (IQR 4-17)).

CONCLUSIONS

Compared to most out-of-hospital resuscitations, resuscitations by lifeboat crews have a low incidence, occur under difficult circumstances and in a younger population. AED's on lifeboats have not contributed to any of the survivals. Analysis of AED information can be used to study the quality of CPR and provide input for improving future training of lifeboat crews.

Post-Mortem Immunohistochemical Evidence of β2-Adrenergic Receptor Expression in the Adrenal Gland

The evidence from post-mortem biochemical studies conducted on cortisol and catecholamines suggest that analysis of the adrenal gland could provide useful information about its role in human pathophysiology and the stress response. Authors designed an immunohistochemical study on the expression of the adrenal β2-adrenergic receptor (β2-AR), a receptor with high-affinity for catecholamines, with the aim to show which zones it is expressed in and how its expression differs in relation to the cause of death. The immunohistochemical study was performed on adrenal glands obtained from 48 forensic autopsies of subjects that died as a result of different pathogenic mechanisms using a mouse monoclonal β2-AR antibody. The results show that immunoreactivity for β2-AR was observed in all adrenal zones. Furthermore, immunoreactivity for β2-AR has shown variation in the localization and intensity of different patterns in relation to the original cause of death. To the best of our knowledge, this is the first study that demonstrates β2-AR expression in the human cortex and provides suggestions on the possible involvement of β2-AR in human cortex hormonal stimulation. In conclusion, the authors provide a possible explanation for the observed differences in expression in relation to the cause of death.

The persistent problem of drowning - A difficult diagnosis with inconclusive tests

Although the diagnosis of drowning may appear straightforward the reality is that it is sometimes one of the most difficult in forensic pathology. To begin with, there is no universal agreement on what constitutes drowning with some definitions using the term in the absence of a lethal outcome. Next are the significant problems that arise in finding immersed bodies and in assessing the death scene. Prolonged post mortem intervals are associated with artefactual modifications of the body from putrefaction and post mortem animal predation. Both of these may create and disguise injuries. The absence of pathognomonic pathological features at autopsy and the presence of potentially life threatening underlying organic illnesses complicate determination of both the cause and manner of death. There may even be no autopsy findings to indicate that immersion had occurred. Finally, the unreliability of laboratory tests with significant overlap with control cases where death had no association with immersion presents further problems. Thus lethal drowning remains a complex event that requires the use of a wide variety of information sources, not just data gleaned from the dissection table.

Non-Traumatic Acute Subdural Hemorrhage Due To Cranial Venous Hypertension

Acute subdural hemorrhage is typically associated with a history of head trauma, and as such it is a finding with significant potential medicolegal consequences. In this article, 37 adult and post-infantile pediatric sudden death autopsy cases with small volume ("thin film" or "smear") acute subdural hemorrhage are presented-in which there is either no further evidence of head trauma or only features of minor head injury. The possible underlying pathophysiological mechanisms are explored, and it is concluded that a common thread in many of these cases is likely to have been cranial venous hypertension at around the time of death. These findings may have implications in instances where small volume subdural hemorrhage is identified in the absence of other evidence of significant head injury.