Immune Cells Characteristics and Their Prognostic Effects in Exertional Heatstroke Patients: A Retrospective Cohort Study

A nomogram based on InLDH and InNLR for predicting disseminated intravascular coagulation in patients with heat stroke

Background

Heat stroke (HS), a potentially fatal heat-related illness, is often accompanied by disseminated intravascular coagulation (DIC) early, resulting in a poorer prognosis. Unfortunately, diagnosis by current DIC scores is often too late to identify DIC. This study aims to investigate the predictors and predictive model of DIC in HS to identify DIC early.

Methods

This retrospective study analyzed clinical data of patients with HS in a tertiary hospital from January 1, 2008 to December 31, 2020. Univariate and multivariate logistic regression analyses were employed to identify the risk factors for DIC in HS. The predictive models based on these risk factors were constructed and externally validated, and their predictive efficacy was evaluated using receiver operating characteristic curves.

Results

A total of 219 HS patients, including 49 with DIC, were included. The independent risk factors for DIC were identified as follows: neutrophil percentage (Neu%), lymphocyte count, lymphocyte percentage (Lym%), creatine kinase-MB (CKMB), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and rhabdomyolysis (RM). After logarithmization, the final predictive model based on the logarithm of lactate dehydrogenase (InLDH; odds ratio (OR) = 9.266, 95% confidence interval (95%CI; 4.379-19.607), p < 0.0001) and the logarithm of neutrophil-lymphocyte ratio (InNLR; OR = 3.393, 95%CI (1.834-6.277), p < 0.0001) was constructed with the largest area under the curve (0.928). A nomogram incorporating InLDH and InNLR was developed and showed excellent discrimination and calibration capabilities.

Conclusion

Nine independent risk factors were identified for the occurrence of DIC in HS patients. The predictive model based on InLDH and InNLR can effectively predict the incidence of DIC. A nomogram based on InLDH and InNLR was developed to facilitate early identification and timely treatment of DIC in HS patients.

Nomogram model for predicting secondary infection in critically ill patients with heatstroke: A pilot study from China

OBJECTIVE

In this retrospective analysis, we explored the clinical characteristics and risk factors of secondary infections in patients with severe heatstroke with the aim to gain epidemiological insights and identify risk factors for secondary infections.

METHOD

The study included 129 patients with severe heatstroke admitted to the General Hospital of the Southern Theater Command of the PLA between January 1, 2011, and December 31, 2021. Patients were divided into an infection group (n = 24) and a non-infection group (n = 105) based on infection occurrence within 48 h of intensive care unit (ICU) admission. Clinical indicators, infection indicators, and clinical outcomes within 24 h of ICU admission were collected and compared between the groups. Independent risk factors for infection in patients with severe heatstroke were analyzed using univariate and multivariate analyses. A nomogram model was constructed, evaluated, and validated.

RESULT

Among the 129 patients with heatstroke, 24 developed secondary infections. Infections occurred between days 3 and 10 post-ICU admission, primarily affecting the lungs. Multivariate analysis identified vasopressor use, serum creatinine level, and gastrointestinal dysfunction at admission as independent risk factors, while elevated lymphocyte count (odds ratio [OR] = 0.167; 95% confidence interval [CI] 0.049-0.572; P = 0.004) was protective against severe heatstroke. Infected patients required longer durations of mechanical ventilation (OR = 2.764; 95% CI, 1.735-4.405; P = 0.044) and total hospital stay than those in the non-infection group. The nomogram model demonstrated clinical feasibility.

CONCLUSION

Increased lymphocyte count is an independent protective factor against infections in patients with severe heatstroke. Vasopressor use, gastrointestinal dysfunction, and elevated serum creatinine levels are independent risk factors. These indicators can aid clinicians in assessing infection risk in patients with severe heatstroke.

Management of Heat-Related Illness and Injury in the ICU: A Concise Definitive Review

OBJECTIVES

The increasing frequency of extreme heat events has led to a growing number of heat-related injuries and illnesses in ICUs. The objective of this review was to summarize and critically appraise evidence for the management of heat-related illnesses and injuries for critical care multiprofessionals.

DATA SOURCES

Ovid Medline, Embase, Cochrane Clinical Trials Register, Cumulative Index to Nursing and Allied Health Literature, and ClinicalTrials.gov databases were searched from inception through August 2023 for studies reporting on heat-related injury and illness in the setting of the ICU.

STUDY SELECTION

English-language systematic reviews, narrative reviews, meta-analyses, randomized clinical trials, and observational studies were prioritized for review. Bibliographies from retrieved articles were scanned for articles that may have been missed.

DATA EXTRACTION

Data regarding study methodology, patient population, management strategy, and clinical outcomes were qualitatively assessed.

DATA SYNTHESIS

Several risk factors and prognostic indicators for patients diagnosed with heat-related illness and injury have been identified and reported in the literature. Effective management of these patients has included various cooling methods and fluid replenishment. Drug therapy is not effective. Multiple organ dysfunction, neurologic injury, and disseminated intravascular coagulation are common complications of heat stroke and must be managed accordingly. Burn injury from contact with hot surfaces or pavement can occur, requiring careful evaluation and possible excision and grafting in severe cases.

CONCLUSIONS

The prevalence of heat-related illness and injury is increasing, and rapid initiation of appropriate therapies is necessary to optimize outcomes. Additional research is needed to identify effective methods and strategies to achieve rapid cooling, the role of immunomodulators and anticoagulant medications, the use of biomarkers to identify organ failure, and the role of artificial intelligence and precision medicine.

Clinical relevance of neutrophil/lymphocyte ratio combined with APACHEII for prognosis of severe heatstroke

We evaluated clinical implication of neutrophil-lymphocyte ratio (NLR) for severe heatstroke and predictive value of combined acute physiology and chronic health evaluation (APACHEII) score for prognosis of severe heatstroke. Retrospectively, we studied 185 individuals that have been admitted at emergency department for severe heatstroke. On the basis of their prognosis, we sorted the patients into two categories, namely non-survival (n = 43) and survival groups (n = 142). The primary outcome was 30-day mortality. A considerably higher NLR was observed among the non-survivors compared to survivors (P < 0.05). After correction for confounders, statistical analysis using multi-variable Cox regression indicated NLR as an independent risk factor for patient death (HR = 1.167, 95%CI = 1.110-1.226, P < 0.001). Through receiver-operating characteristics (ROC) curve, we estimated area-under the curve (AUC) of NLR to be 0.7720 (95% CI [0.6953, 0.8488]). Also, transformation of NLR into a profile type analysis showed that the marker remained a risk factor for death, which showed trend variation (P for trend <0.001). Subgroup forest plot analysis showed robustness in the predictive ability of NLR after exclusion of confounders. Besides, we demonstrated through Kaplan-Meier (KM) survival analysis curve that high risk NLR mortality substantially exceeded low risk NLR. The combined prediction of NLR and APACHEII achieved higher efficacy than NLR and APACHEII alone (AUC = 0.880, 95% CI [0.8280, 0.9290]). Additionally, Delong test indicated that the combined prediction demonstrated a significantly greater ROC than NLR and APACHEII alone, while DCA showed a considerably higher clinical net benefit rate. Increased NLR is a high risk factor and has predictive value for death in individuals with severe heatstroke. Suggestively, combination of NLR and APACHEII have greater predictive value.

Heatstroke-induced acute kidney injury and the innate immune system

Heatstroke can cause multiple organ failure and systemic inflammatory response syndrome as the body temperature rises beyond the body's ability to regulate temperature in a hot environment. Previous studies have indicated that heatstroke-induced acute kidney injury (AKI) can lead to chronic kidney disease. Therefore, there is an urgent need to elucidate the mechanism of heatstroke-induced AKI and to establish methods for its prevention and treatment. Recent reports have revealed that innate immunity, including neutrophils, macrophages, lymphocytes, and mast cells, is deeply involved in heat-induced AKI. In this review, we will discuss the roles of each immune cell in heat-induced renal injury and their potential therapeutic use.

A nomogram based on lymphocyte percentage for predicting hospital mortality in exertional heatstroke patients: a 13-year retrospective study

BACKGROUND

Exertional heatstroke (EHS) is a life-threatening disease without ideal prognostic markers for predicting hospital mortality.

METHODS

This is a single-center retrospective study. Clinical data from EHS patients admitted to the Intensive Care Unit (ICU) of the General Hospital of Southern Theatre Command between January 1, 2008, and December 31, 2020, were recorded and analyzed. Univariate and multivariate logistic regression were used to identify the factors for mortality. The prediction model was developed with the prognostic markers, and a nomogram was established.

RESULTS

The study ultimately enrolled 156 patients, and 15 (9.6%) of patients died before discharge. The lymphocyte count (Lym) and percentage (Lym%) were significantly lower in non-survivors (P<0.05). The univariate and multivariate logistic regression analyses indicated that Lym% at the third day of admission (Lym% D3) (OR=0.609, 95%CI: 0.454-0.816) and hematocrit (HCT) (OR=0.908, 95%CI: 0.834-0.988) were independent protective factors for hospital mortality. A nomogram incorporating Lym% D3 with HCT was developed and demonstrated good discrimination and calibration ability. The comparison between the prediction model and scoring systems revealed that the prediction model had the largest area under the curve (AUC) (0.948, 95%CI: 0.900-0.977), with 100.00% sensitivity and 83.69% specificity, and a greater clinical net benefit.

CONCLUSION

Severe EHS patients had a higher risk of experiencing prolonged lymphopenia. A nomogram based on Lym% D3 and HCT was developed to facilitate early identification and timely treatment of patients with potentially unfavorable prognoses.