Association of admission serum potassium abnormalities and short -term outcomes in patients with major trauma in Mulago National Referral Hospital

Abstract

Background: Injuries are a major cause of morbidity and mortality worldwide, with more than 90 % of injury deaths occurring in Low- and Middle-income countries (LMIC). Trauma causes changes which are known as metabolic response to injury. These metabolic changes can lead to extracellular potassium abnormalities which can cause various clinical problems in trauma patients. In Mulago National Referral Hospital, patient resuscitation to correct hypotension from volume loss still majorly relies on use of physiological parameters such as blood pressure, pulse rate, respiratory rate, urine output, and oxygen saturation. However, use of these parameters may not be sufficient to detect occult tissue hypoxia, and the accompanying metabolic derangements. Blood potassium levels increase in trauma as a response to hemorrhagic shock hence can be used as a marker in injury scoring and management of trauma. There is also a reduction in serum potassium in trauma due to release of adrenaline. Commonly used injury scoring tools like the Kampala Trauma Score do not use serum potassium as a means of stratifying injury but rather focus on anatomical and physiological parameters that fail to detect electrolyte derangements that may contribute to morbidity and mortality. This study explored the relationship between severity of trauma with potassium as a biomarker of tissue damage and how this biomarker relates to short- term clinical outcomes.

Objective: To determine the admission potassium abnormalities and their association with outcomes among major trauma patients in MNRH.

Methods: This was an observational prospective study involving major trauma patients admitted to MNRH between September and November 2021. Major trauma patients admitted in MNRH were assessed against the exclusion criteria and participants in the research selected. Also, data on sociodemographic characteristics, clinical characteristics, serum potassium levels, KTS- II score, and outcomes of major trauma such as death, surgery, ICU admission was collected. Data was entered in Epidata version 3.1 and analysis was conducted using STATA version 14.1. Descriptive analysis involved obtaining means and medians for continuous variables and proportions and percentages of categorical variables. Association with mortality was assessed using logistic regression and odds ratio (OR) and Hazard Ratio (HR) reported with their corresponding 95 % CI and level of significance set at alpha 0.05. This was a prospective observational nonintervention study and the recruited patients were followed up for 7 days. The admission venous serum potassium findings were associated with the patient’s clinical outcome. Utility of Findings: The study findings will be used to accurately triage major trauma patients and tailor resuscitation protocols and improve clinical outcomes of patients.

Results: Of the 900 participants seen at the Mulago A & E Department during the study period, 123 had major trauma. The male to female ratio was 5:1 and mean age was 34 (SD12).

Of the participants, 120 met the inclusion criteria and had venous potassium blood samples drawn for measurement of admission serum potassium (normal range 3.5 - 5.5mmol/l). Mean initial potassium was 4.3 and mean follow up value was 4.4 for men, mean value for women was 4.1. Range was 2.6 - 6.7mmol/l.

Among the participants, 9(7.5%) had ICU admission and 45 (37.5%) had emergency surgery done. Ninety seven (97) participants (80.3%) had accidents as cause of injury with the biggest percentage having at least craniocerebral injury. Of the 120 participants, 38 (31.7 %) had admission serum potassium abnormalities. There was an overall mortality of 33 (27.5 %). Among the participants that died, 60.7% had admission serum potassium abnormalities. Patients with low admission serum potassium levels were 6.26 times at risk of death compared to those with normal potassium level. Those with high potassium levels had 8.5 times risk of death compared to those with normal potassium.

Conclusion: There is a strong association between admission serum potassium abnormalities and outcomes and thus admission serum potassium levels may be considered as an alternative marker of injury severity among critically ill patients.