Incidence and outcomes of dysnatremia in crush injury patients admitted to Türkiye’s largest hospital following the Kahramanmaraş earthquake

Abstract

Objectives

Dysnatremia is a critical electrolyte disturbance that can significantly impact the prognosis of trauma patients by influencing fluid balance, neurological function, and hemodynamics. Although sodium disorder is common in hospitalized patients, few studies have specifically examined the incidence of dysnatremia in patients presenting to the emergency department for post-earthquake trauma. The aim of this study is to evaluate the incidence of dysnatremia and the prognosis of patients with dysnatremia in trauma patients admitted to our center after the Kahramanmaraş earthquake.

Materials and methods

Between February 6th, 2023 and February 20th, 2023, a total of 422 patients with earthquake-related crush injuries after the Kahramanmaras earthquake were retrospectively analyzed. Patients were divided into two groups: the survivor group and the exitus group. Then, patients with dysnatremia were evaluated. Age, gender, the city where patients came from, type of presentation, injured organ systems and extremities, laboratory findings, ward admission, intensive care admission, GCS, MESS, ISS, RTS, TRISS, and hemodialysis sessions were analyzed.

Results

A total of 422 earthquake victims with crush injuries were included in the study. Dysnatremia was present in 28% of the patients, and these patients had a longer hospital stay. GCS was lower, MESS and ISS values were higher, and survival rates according to TRISS were lower. Multiple extremity trauma, crush syndrome, and dialysis rates were more common in the dysnatremia group. Additionally, fasciotomy, amputation and mortality rates were higher in the dysnatremia group.

Conclusion

Dysnatremia is a common finding in patients with crush injuries and is associated with more severe trauma and poorer clinical outcomes. This study highlights the need for close monitoring and management of sodium disturbances in trauma patients, not only in the context of earthquakes but across various disaster scenarios. Recognizing and addressing dysnatremia can contribute to improved patient outcomes in disaster and emergency settings.

Introduction

On February 6, 2023, at 04:17, a 7.7 magnitude earthquake struck in Kahramanmaraş province of Türkiye, followed by another earthquake of 7.6 magnitude nine hours later at 13:24 on the same day. According to the Mercalli intensity scale, the intensity of the tremors was determined as XII (Catastrophic), the highest value on the scale. These earthquakes caused significant damage across 11 provinces in Türkiye. While hundreds of people lost their lives under the rubble, many others died due to trauma and related complications [1]. According to official figures, approximately 9.1 million people in Türkiye were affected, around 50,000 people died, and at least 115,000 were injured [2, 3].

Earthquakes are natural disasters that cause massive destruction, severe traumas, and sudden deaths. Fatalities that occur immediately at the earthquake site are often due to traumatic causes, including entrapment under debris, severe impact, and crush injuries. Among individuals who survive the immediate aftermath of the earthquake, especially those who remain under the rubble for extended periods, crush injuries and the subsequent development of crush syndrome are frequently observed [4, 5]. Crush syndrome is a clinical condition that develops due to prolonged compression of skeletal muscles, leading to the breakdown of muscle tissue and the release of systemic toxic substances into the bloodstream. This condition can result in severe complications such as acute kidney failure, hypovolemic shock, and hyperkalemia. Hyperkalemia is one of the most significant and fatal consequences of crush syndrome and requires urgent treatment [6]. However, among the electrolyte imbalances observed in crush syndrome, sodium disturbances are also present, although the data on this issue are more limited compared to hyperkalemia, and their effects on clinical outcomes are not yet fully clarified [7, 8].

Sodium plays a vital role in maintaining fluid balance and cellular function, which are critical in trauma patients. In crush injury, disturbances in sodium levels can affect essential parameters such as fluid management, tissue perfusion, and neurological status, potentially influencing patient outcomes. Therefore, the aim of this study is to determine the incidence of sodium disturbances in patients presenting to the hospital with crush injuries due to trauma following an earthquake and to evaluate the the prognosis of patients with dysnatremia.

Materials and methods

Data collection

Ankara Etlik City Hospital is the largest hospital in Türkiye. It is fully equipped for surgical procedures and has a hyperbaric unit and a helicopter ambulance landing pad. The facility has a capacity of 4,050 beds, 1,000 outpatient clinics, 125 operating rooms, 869 intensive care unit (ICU) beds, and a total enclosed area of 1,145,129 m². Some patients were transferred from the earthquake zone to the hospital by air ambulances or ground transportation, while others arrived by their means. All patients arriving from the earthquake zone were initially admitted to the emergency department of our hospital and assessed in a dedicated trauma area reserved for these patients. Emergency physicians first evaluated patients and were subsequently assessed by specialists from all surgical branches, internal medicine, and intensive care subspecialists. The collective decisions of all involved physicians guided the management of the patients. All patients were registered in the hospital information management system with the ‘Earthquake Victim ICD-X34’ code. All patient records are recorded in the hospital information management system in a computer environment and can be accessed anytime. Whether the patients had crush injuries was analyzed based on the emergency room physicians’ notes, consultation notes in hospital records, and imaging findings (x-ray, computed tomography, etc.). The diagnosis of crush syndrome was made by the internal medicine physicians after the internal medicine consultation and was recorded in the consultation notes.

Inclusion criteria

• Patients presenting to the emergency department with physical trauma due to the earthquake.

• Patients presenting to the emergency department with the ‘Earthquake Victim ICD-X34’ code.

• Age over 18 years.

Exclusion criteria

• Patients arriving from the earthquake zone but presenting for non-traumatic reasons.

• Patients for whom data from the retrospective study form were unavailable.

• Patients without sodium and concurrent glucose values.

Definitions

Dysnatremia

The initial serum sodium concentration was adjusted according to the concurrently measured serum glucose level in this analysis. The relationship between serum sodium and hospital mortality is non-linear and U-shaped. Therefore, serum sodium was treated as a categorical variable. Hyponatremia was categorized as borderline (130 ≤ Na < 135 mmol/L), mild (125 ≤ Na < 130 mmol/L), or severe (< 125 mmol/L). Hypernatremia was also categorized as borderline (145 < Na ≤ 150 mmol/L), mild (150 < Na ≤ 155 mmol/L), or severe (> 155 mmol/L). Normal serum sodium (135 ≤ Na ≤ 145 mmol/L) was the reference category. All values outside the normal range were classified as dysnatremia [9].

Crush injury

An injury resulting from the direct physical impact of a heavy object on the muscles.

Crush syndrome

Crush syndrome is defined as the systemic manifestations resulting from crush injury and can lead to organ dysfunction (primarily acute kidney injury (AKI), but multisystem organ damage may also occur) or death [2,3,4,5]. The symptoms of crush syndrome are typically systemic consequences of muscle damage, particularly rhabdomyolysis, which often results in AKI. This condition, also known as rhabdomyolysis, involves a series of metabolic changes caused by severe injury to skeletal muscles, disrupting cellular integrity and releasing intracellular contents into circulation. Serum creatine kinase (CK) levels above 1000 IU/L and associated clinical features are typically considered indicators of crush syndrome. The normal range is 25–175 U/L; levels usually rise 2 to 12 h after the crush injury, peak within 1 to 3 days, and decline after 3 to 5 days [10, 11].

Calculation of prognostic scores

Glasgow coma scale (GCS)

GCS developed in 1974, is a widely used tool for assessing a patient’s level of consciousness. It scores three parameters—eye response, verbal response, and motor response—ranging from 3 (worst) to 15 (best).

Mangled extremity severity score (MESS)

MESS was developed 25 years ago at Harborview Medical Center in Seattle by Johansen and colleagues in an attempt to create a tool that accurately predicts the need for amputation [12]. MESS considers the degree of skeletal and soft tissue injury, limb ischemia, the presence of shock, patient age, and the duration of ischemia. The score ranges from 1 to 14, with scores of 7 or higher predicting a low likelihood of limb viability.

Injury severity score (ISS)

ISS divides the body into six regions corresponding to major injuries: head or neck, face, chest, abdomen, extremities, and external. Each region is assigned an injury severity score ranging from 0 to 6. The ISS is calculated as the sum of the squares of the highest injury scores from the three most severely affected regions, resulting in a total score ranging from 1 to 75. Notably, any injury with a severity score of 6 automatically results in an ISS of 75 [13]. The ISS was developed by trained staff at the United States Army Institute of Surgical Research according to the methods described by the Association for the Advancement of Automotive Medicine Abbreviated Injury Scale, 1998 Revision [14].

The revised trauma score (RTS)

RTS is a physiological scoring system based on a patient’s initial vital signs. It comprises three categories: GCS, systolic blood pressure (SBP), and respiratory rate (RR). The scores obtained from these three main parameters (GCS, SBP, RR) are then used to calculate a weighted sum using the formula: “RTS = 0.9368 GCS + 0.7326 SBP + 0.2908 RR.” The RTS score ranges from 0 to 7.8408. RTS was developed specifically for patients with major head trauma without multisystem injuries or significant physiological changes. It is recommended that patients with an RTS < 4 be evaluated at a trauma centre. The RTS is inversely correlated with clinical outcomes, indicating that as the score decreases, the clinical condition worsens. This scoring system is also used in patient triage [15]. Low RTS and ISS scores greater than 16 (ranging from 16 to 75) are associated with high mortality rates.

The Trauma score and injury severity score (TRISS)

TRISS adjusts for age and the nature of the trauma (penetrating or blunt). It combines RTS and ISS through a statistical model to determine the probability of survival. Higher scores are associated with an increased likelihood of survival [15,16,17,18,19]. The scores were calculated based on emergency physicians’ notes and consultation notes from hospital records, as well as imaging findings (X-ray, Computed tomography, e.g.). The Ethics Committee of Ankara Etlik City Hospital (AEŞH-BADEK-2024063) approved the study. The study was conducted by the Ethical Principles of the Declaration of Helsinki by the World Medical Association.

Statistical analysis

Continuous variables were expressed as median ± quartiles (IQR), while categorical variables were presented as numbers and percentages. The normality assumption for numerical variables was evaluated both analytically (Kolmogorov-Smirnov test, the Shapiro-Wilk test) and graphically (histogram). The chi-square test was used to compare categorical variables for bivariate analysis, while the Kruskal-Wallis test will be utilized to compare two or more independent variables. Since the data did not follow a normal distribution, The Mann-Whitney U test was used for the binary group comparison of numerical variables, and the Kruskal-Wallis test was used for comparisons involving three or more groups. SPSS version 23.0 statistical software package (IBM, Armonk, NY, USA) was used to analyze the research data. A two-sided p-value of less than 0.05 was considered to be statistically significant.

Results

A total of 2,528 patients presented to our hospital following the earthquake. 659 patients were excluded due to missing data. 1,447 patients were excluded because they presented for non-traumatic reasons or due to duplicate records. As a result, 422 patients who met the inclusion criteria were analyzed in this study. Of these patients, 152 (36%) were from Hatay, 120 (28.4%) from Kahramanmaraş, 110 (26.1%) from Adıyaman, 20 (4.7%) from Gaziantep, 9 (2.1%) from Adana, 8 (1.9%) from Malatya, 2 (0.5%) from Şanlıurfa, and 1 (0.2%) from Osmaniye.

303 (71.8%) patients were transported by air and ground ambulances directly from the scene or local hospitals where initial interventions had been performed. In contrast, 119 (28.2%) patients arrived at our hospital from the earthquake zone by their means. Among the 422 patients included in the study, 25 patients were discharged directly from the emergency department, 229 were admitted to the general wards, and 168 required ICU admission. A total of 48 (11.4%) patients underwent hemodialysis due to crush syndrome, and mortality was observed in 19 patients (4.5%).”

31 (7.3%) patients who had undergone amputations at local hospitals in the earthquake zone were transferred to our facility, while 31 (7.3%) patients underwent amputations at our hospital. Additionally, 78 (18.5%) patients underwent fasciotomy, and 106 (25.1%) patients received other surgical procedures related to their extremities, including soft tissue debridement, internal fixation, external fixation, and local flaps.

Vital signs and many laboratory parameters in the mortality group were significantly worse, and all prognostic scores were statistically significantly poorer in the mortality group. Table 1 summarizes the characteristics of the study population at admission according to their outcomes. Additionally, Appendix Table A1: Detailed Laboratory Parameters and Injured Body Part has been provided.

Table 1 Comparison of variables in “Mortality” groups

Patients with dysnatremia had a longer hospital stay. GCS scores were lower, while MESS and ISS scores were higher in the dysnatremia group, and survival rates according to TRISS were lower. Multiple extremity trauma, crush syndrome, and dialysis rates were more prevalent in the dysnatremia group. Additionally, the rates of fasciotomy and amputation were higher among patients with dysnatremia. Detailed data are shown in Table 2.

Table 2 Characteristics of patients with and without dysnatremia

Seventy-two per cent of the patients had normal sodium levels. Patients with hypernatremia had a more extended ICU stay, while those with hyponatremia had a longer ward stay. Patients with severe hypernatremia had a median GCS of 8, and RTS was lower compared to other groups. According to TRISS, MESS and ISS were higher in hyponatremic and hypernatremic patients, and survival rates were lower in hypernatremic patients. Adverse outcomes such as crush syndrome, dialysis, fasciotomy, amputation, and mortality were higher in the hyponatremia group. Detailed data are shown in Table 3.

Table 3 Characteristics of patients with and without dysnatremia (hyponatremia/hypernatremia)

Discussion

This study described the incidence of dysnatremia in patients with crush injuries who were transferred to the largest hospital in Türkiye following the Kahramanmaraş earthquake. This study shows that dysnatremia is common in patients with crush injuries and accompanies more severe injuries and poor prognosis.

Sodium is a critical electrolyte for normal physiological function, and sodium disturbances are known to have adverse effects on cardiac, neurological, and renal functions. In general, the Association between dysnatremia and increased mortality is thought to be a combination of the effects of underlying organ dysfunction and the harmful consequences of dysnatremia itself. Patients with crush injuries resulting from earthquakes experience severe pain and extreme fear, which stimulates the release of vasopressin. Prolonged compression leads to muscle ischemia, and reperfusion further contributes to injury. The sarcolemma loses its functional integrity, leading to the development of intracellular oedema and a reduction in intravascular volume [20]. This also promotes the activation of the renin-angiotensin system, vasopressin, and the sympathetic nervous system, ultimately leading to the development of hyponatremia in patients. Westermann et al. found that vasopressin levels were significantly elevated in patients with multiple traumas [21]. Zhang et al. found that patients with hyponatremia had more severe traumatic injuries, and hyponatremia was independently associated with greater third-space fluid loss and the number of crushed extremities. [8] In our study, it was found that patients with dysnatremia had a higher incidence of multiple extremity injuries, higher injury severity scores such as MESS and ISS, and increased rates of fasciotomy, amputation, and dialysis. Additionally, the probability of survival, as indicated by the TRISS score, was significantly reduced. Among patients with hyponatremia, MESS and ISS scores, as well as the rates of amputation, dialysis, and mortality, were found to be higher. This supports the hypothesis in the literature that patients with sodium disturbances tend to have more severe injuries. While it is difficult to draw a definitive conclusion about the direct relationship between hyponatremia and mortality, the odds ratio in Zhang et al. [8]’s study remained highly significant even after adjusting for comorbidities, highlighting the link between hyponatremia and poor clinical outcomes. Therefore, our findings suggest that the diagnosis and management of dysnatremia are critical in trauma care. Close monitoring of sodium levels and prompt correction are essential for preventing complications in these patients.

In our study, we found that patients with sodium disturbances (dysnatremia) had longer ward stays, longer ICU stays, and more extended total hospital stays. This indicates that electrolyte imbalances severely disrupt body homeostasis and prolong recovery. This may be because both hyponatremia and hypernatremia can cause intracellular and extracellular fluid imbalances, negatively affecting organ functions, particularly leading to neurological, cardiac, and renal dysfunction. Additionally, hyponatremia, in particular, can exacerbate inflammation and tissue damage following trauma, worsening the severity of the injury. Hyponatremia is known to be the most common electrolyte disturbance in adult patients admitted to the ICU, with the prevalence of hyponatremia at ICU admission ranging from 13.7 to 17.7% [9, 22]. The risk of mortality at hospital admission was increased in patients admitted with hyponatremia compared to those with normonatremia [23]. Hyponatremia present at ICU admission is an independent risk factor for poor prognosis [9]. In our study, 36.9% of the patients admitted to the ICU had hyponatremia. The high prevalence observed in this study may be attributed to the fact that all of our patients were trauma patients, with a high severity of trauma and the release of vasopressin due to associated stress and pain. Additionally, this may be related to transferring more critically ill patients to our centre, as it is the largest hospital in Türkiye, from local hospitals in the surrounding earthquake-affected areas where their conditions could not be managed.

In the dysnatremia group, there was a significant increase in the need for dialysis. This may be an essential indicator of the frequency of co-occurrence of kidney injury and electrolyte imbalances, as well as the extent to which renal dysfunction worsens the prognosis. Consistent with a similar study in the literature, 62.5% of the patients requiring dialysis in this study had hyponatremia [8]. An important point is that patients with borderline hyponatremia constituted the largest group requiring dialysis. Even mild hyponatremia is known to be associated with increased mortality [23]. Considering that none of the patients arrived from the scene without receiving isotonic saline, this suggests that they may have had more severe underlying hyponatremia initially. The fact that 89.5% of the patients with fatal outcomes had either hyponatremia or normal sodium levels further supports this hypothesis.

Sodium disturbances, such as hyponatremia and hypernatremia, have different clinical effects. Hyponatremia can lead to intracellular fluid accumulation and cerebral oedema, causing neurological dysfunction, while hypernatremia is associated with dehydration, kidney failure, and cardiac arrhythmias. These conditions result in more severe complications and prolonged recovery times in trauma patients. In our study, patients with hyponatremia were observed to have longer ward stays, while those with hypernatremia had longer ICU stays. The median GCS of patients with severe hypernatremia was lower than that of other groups, and all patients in this group had multiple extremity injuries. While all patients with severe hyponatremia underwent fasciotomy, hyponatremic patients also had the highest rates of amputation. When considering crush syndrome, dialysis treatment, fasciotomy, amputation, and mortality, patients with hyponatremia and normal sodium levels had higher rates compared to the hypernatremic group. In the study by Rana et al. [24], although hypernatremic patients were proportionally higher in the mortality group, only 5 patients in the mortality group had hypernatremia, and there was no difference in sodium levels between the groups. In the limited number of similar studies in the literature, such as the study by Zhang et al. [8], hyponatremia was found to be more risky in terms of prognosis. In the study by Zhang et al., which evaluated 180 victims of the Wenchuan earthquake, only hyponatremic patients were assessed, and hyponatremia was observed in 50% of patients with crush injuries. Although the rate in our study was lower (22%), similarly, hyponatremic patients were more common compared to hypernatremic patients and represented a group at higher risk in terms of prognosis. In patients with crush injuries, hyponatremia occurs due to vasopressin release triggered by stress and pain, as well as intracellular edema resulting from muscle ischemia and the loss of functional integrity of the sarcolemma. Considering this pathophysiological process, we argue that hyponatremia is a more prevalent electrolyte disturbance in patients with crush injuries and is of greater significance in terms of prognosis.

This study has several limitations. First, due to the chaotic disaster conditions, there were some missing data in the retrospectively collected information. The patient distribution between the groups was not balanced. In our single-center study, sodium levels during hospital stays were not monitored. Furthermore, no data were obtained on prehospital oral or intravenous fluids, which could have influenced sodium levels in patients with crush injuries during the earthquake. However, since it is known that providing fluids from the moment of extrication can prevent the development of crush syndrome and related complications, nearly all patients should arrive at the hospital having received fluids.

It should be noted that the dysnatremias observed could have developed either despite the fluids administered or as a result of them. Therefore, we recommend controlled fluid replacement and close monitoring of sodium levels both in the prehospital care, emergency department and during ICU or ward follow-ups. Additionally, it should be remembered that patients with crush injuries experience vasopressin release due to pain and stress, and the analgesic medications administered may contribute to sodium balance.

Due to the limited sample size in our study, it was not feasible to perform logistic regression analysis to determine whether dysnatremia independently influences mortality. Although higher rates of dysnatremia were observed in the mortality group, this Association does not imply causation. Dysnatremia likely contributes to mortality, albeit not in isolation but rather in conjunction with numerous other factors previously documented in the literature. Verification of this Association would require logistic regression analysis with a larger sample size to yield statistically robust results.

Conclusion

Dysnatremia is a common finding in patients with crush injuries, often associated with more severe trauma and poorer clinical outcomes. This study highlights the critical importance of recognizing and managing dysnatremia in trauma patients to improve outcomes. Although this research was conducted in the context of the Kahramanmaraş earthquake, the findings underscore the broader relevance of monitoring and addressing dysnatremia in various disaster and trauma settings. Controlled fluid replacement and close monitoring of sodium levels are essential across all stages of care, including pre-hospital settings, emergency departments, and inpatient units. These results contribute to the understanding of dysnatremia’s role in trauma care and provide a foundation for future research in disaster medicine.