Management of accidental hypothermia: A narrative review

Identifying hypothermia death in a mouse model by ATR-FTIR

The identification of hypothermia death (HD) is difficult for cadavers, especially the distinction from death due to alternative causes. A large number of studies have shown that brown adipose tissue (BAT) plays critical roles in thermoregulation of mammals. In this study, BAT of mice was used for the discrimination of HD using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). A modified mouse HD model conducted by Feeney DM was used in this study to obtain infrared spectra of BAT. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to establish discrimination models. The PLS-DA and OPLS-DA models exhibit prominent discriminative efficiency, and the accuracy of HD identification using fingerprint regions and ratios of absorption intensity is near 100% in both the calibration and validation sets. Our preliminary study suggests that BAT may be an extremely effective target tissue for identification of cadavers of HD, and ATR-FTIR spectra combined with chemometrics have also shown potential for cadaver identification in forensic practice in a fast and accurate manner.

Therapeutic donor hypothermia following brain death to improve the quality of transplanted organs

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

This review aims to examine the benefits and harms of therapeutic donor hypothermia in recipients or organs donated after brain death.

The Value of Myocardium and Kidney Histopathological and Immunohistochemical Findings in Accidental Hypothermia-Related Fatalities

Background and Objectives: The post-mortem diagnosis of hypothermia is challenging in forensics. The aim of our study was to detect the kidney and heart histopathological changes that occurred in a group of hypothermia-related fatalities. Materials and Methods: The cohort included 107 cases identified in the database of our department between 2007 and 2021, which have been associated with extreme cold stress. Demographic and clinicopathological data were collected from the medico-legal reports. Archived tissue samples were evaluated to identify the histopathological features, in routine haematoxylin-eosin (H&E), Periodic acid-Schiff (PAS), and Masson's trichrome stainings, while cardiac sirtuin1 (SIRT1) and renal ubiquitin (Ub) immunostaining have been performed. Results: The majority of cases exposed to low temperatures were males (76%) from rural regions (68.2%) during the cold season. Paradoxical undressing was documented in 9.3% of cases. The common comorbidities included alcoholism (50.5%), neuropsychiatric diseases (10.3%), diabetes mellitus (3.7%), and lung tuberculosis (4.7%). The microscopic heart exam revealed areas of myocardial degeneration (100%), contraction bands (95.3%), fatty change (13.1%) and focal wavy contractile myocardial cells. Basal vacuolisation of renal tubular epithelial cells (Armanni-Ebstein lesions) (21.5%), focal tubular necrosis (7.5%), tubular renal cysts (7.5%), interstitial haemorrhages (5.6%), diabetic kidney disease (3.7%), background benign nephroangiosclerosis (42.1%), variable thickening of tubules and corpuscles basement membranes, capsular space amorphous material, and intratubular casts were identified in kidney tissue samples. Myocardial cells displayed SIRT1 weak expression, with a loss of immunopositivity correlated with areas with contraction bands, while a variable Ub expression was observed in renal corpuscles capsules, proximal, distal, and collecting renal tubules, Henle's loops, urothelium, and intratubular casts. Conclusions: In the context of the current concept that death associated with hypothermia is still a diagnosis of exclusion, our findings suggest that the microscopic exam provides relevant data that support the diagnosis of hypothermia-related fatalities in appropriate circumstances of death. A deeper insight into the histopathologic findings in hypothermic patients may lead to new therapeutic approaches in these cases.

Effects of Different Types of Early Restrictive Fluid Resuscitation on Immune Function and Multiorgan Damage on Hemorrhagic Shock Rat Model in a Hypothermic Environment

Objective

This study was aimed at investigating the effects of different types of fluid restriction fluid resuscitation on the immune dysfunction and organ injury of hemorrhagic shock rats under a hypothermic environment.

Methods

SD rats were divided into sham operation group (SHAM), hemorrhagic shock model group (HS), crystal liquid limited resuscitation group (CRLLR), colloidal liquid limited resuscitation group (COLLR), and nonlimited resuscitation group (NLR); rats in each group were placed in a low-temperature environment of 0-5°C for 30 min, and then, a hemorrhagic shock rat model was prepared. Sodium lactate Ringer's restricted resuscitation solution, hydroxyethyl starch restricted resuscitation solution, and hydroxyethyl starch were used for resuscitation, and hemodynamic examination was performed. The mortality rate, inflammatory factors, oxidative stress factors, and immune function were detected by ELISA. The dysfunction and injury of the intestinal, lung, liver, and kidney were examined by histological methods.

Results

Hemorrhagic shock resulted in decreased immune function and activation of inflammation. Unrestricted fluid infusion further activated the inflammatory response. The crystalloid-restricted fluid infusion performed effectively to regulate inflammatory response, promote antioxidative activity, and reduce the immunosuppressive reaction. Rehydration could regulate the coagulation. The hydroxyethyl starch reduced the expression of platelet glycoproteins Ib and IIb/IIIa and blocked the binding of fibrinogen to activated platelets, thereby inhibiting intrinsic coagulation and platelet adhesion and aggregation. Rats in the CRLLR group showed to relieve the injury of the lung, liver, kidney, and intestine from hemorrhagic shock in low-temperature environment.

Conclusion

The early application of restrictive crystalloid resuscitation in hemorrhagic shock rats in hypothermic environment showed the best therapy results. Early LR-restrictive fluid replacement promotes the balance of inflammatory response and the recovery of immunosuppressive state, resists oxidative stress, stabilizes the balance of coagulation and fibrinolysis, improves coagulation function, and relieves organ injury.