Clinical Assessment of Low Calcium In traUMa (CALCIUM)

Overview

Major trauma frequently occurs in the deployed, combat setting and is especially applicable in the recent conflicts with explosives dominating the combat wounded. In future near-peer conflicts we will likely face even more profound weapons including mortars and artillery. As such, the number of severely wounded will likely increase. Hypocalcemia frequently occurs after blood transfusions secondary to the preservatives in the blood products, however, recent data suggests that major trauma in and of itself is a risk factor for hypocalcemia. Calcium is a major ion involved in heart contractility and thus hypocalcemia can lead to poor contractility. Smaller studies have linked hypocalcemia to worse outcomes, but it remains unclear what causes hypocalcemia and if intervening could potentially save lives. We are seeking to address the following scientific questions, (1) Is hypocalcemia present following traumatic injury prior to transfusion during resuscitation? (2) Does hypocalcemia influence the amount of blood products transfused? (3) To what extent is hypocalcemia further exacerbated by transfusion? (4) What is the relationship between hypocalcemia following traumatic injury and mortality? The investigators will conduct a multicenter, prospective, observational study. The investigators will gather ionized calcium levels at 0, 3, 6, 12, 18, and 24 hours as part of scheduled calcium measurements. This will ensure that the investigators have accurate data to assess the early and late effects of hypocalcemia throughout the course of resuscitation and hemorrhage control. These data will be captured by a trained study team personnel at every site. Our findings will inform clinical practice guidelines and optimize the care delivered in the combat and civilian trauma setting.

OBJECTIVES/SPECIFIC AIMS/RESEARCH QUESTIONS The investigators will determine the incidence of hypocalcemia on hospital arrival and the association with survival. Aim 1: Overall incidence of hypocalcemia on ED arrival in major trauma patients Aim 2: Association of hypocalcemia with severity of hemorrhage Aim 3: Association of hypocalcemia with the number of blood products transfused and supplemental calcium administration Aim 4: The association of hypocalcemia with early and 24-hour mortality. RESEARCH PLAN Research Design: The investigators will conduct a prospective, multicenter, observational study. Subject Population(s) Trauma patients that are brought in as a trauma activation will be sought. Number of Subjects, Records, and/or Specimens- Approximately 391 Inclusion Criteria The Investigators will include any patient that meets trauma activation criteria for the amendment of our order set. However, for our primary outcome analysis the investigators will use the following inclusion criteria based on the "major trauma" activation criteria at the primary site (BAMC): Penetrating trauma to the head, neck, torso, or extremities (proximal to the elbow/knee) Traumatic arrest or CPR at any time Glasgow Coma Scale of 9 or less or deteriorating from initial arrival Systolic blood pressure \<100mmHg Respiratory rate \<10 or \>29 Intubated or requiring airway assistance (e.g. bag-valve mask, etc.) Any blood administered prehospital Vasopressors administered Pulseless, degloved, crushed, or mangled extremity proximal to the wrist Evidence of arterial bleeding with or without tourniquet application Amputations proximal to the wrist/ankle Chest needle decompression or chest thoracostomy Exclusion Criteria: The investigators will exclude patients that are known or suspected to be pregnant, less than , or prisoner status. Research Procedures 1\. Identification of Trauma Subjects (BAMC) Trauma patients for enrollment in the study will be identified using our trauma activation protocols in the emergency department. The decision to use trauma team activations will be solely at the discretion of the clinical team. All trauma patients coming in the emergency department that meet criteria for trauma activation will be potential subjects for capture in the study. The investigators will enroll a generally continuous sample by amending our current standard trauma order set which currently requires the following tubes be drawn on every trauma activation upon arrival: 1 green top (ionized calcium source) lavender top blue tops 1 pink top 1 red top 1 blood gas tube 1 TEG tube In addition to the order set change, the investigators will promote capture by way of staff education, staff reminders, staff-facing signage, and dissemination via routine department communications. 2\. Obtaining Trauma Subject Blood Samples (BAMC) All patients coming in as part of trauma activations have a standard blood panel order set that is placed as outlined above. Blood draw happens as part of routine clinical care for all trauma activations. As part of the study, the investigators will use existing blood that is drawn as part of routine clinical care, or when necessary, draw additional blood to obtain samples at 0, 3, 6, 12, 18, and 24 hours assessing ionized calcium, serum calcium, and magnesium. The investigators will strive to have draws occur within +/- 1 hour of the goal times. However, given that the blood draws will be performed by way of the clinical team and the unpredictable nature of trauma care, missed draws or draws out of the goal time frame will not be considered protocol violations. 3\. Storage of the Blood Samples (BAMC) The tubes of blood will be handled per the current standard operating procedures (SOP). The lab studies will be done based on the institutional equipment requirements and SOPs. No banking or repository of blood samples is planned for this study so all specimen storage and destruction will be based on the laboratory SOPs. 4\. Data Extraction Data extraction will occur via three methods: A study team member will perform manual data extraction by way of medical records review, and/or a study team member will submit the patient information along with the approved data extraction variable list to the designed point of contact within the information management division (IMD) for EMR data repository data extraction, and/or a study team member will submit the patient information along with the approved data extraction variable list to the designed point of contact within the local trauma registry team. 5\. Data Aggregation Data will be aggregated by a study team member into a local database. The data will be stored locally along with the master key that links all the data back to the patients in the event additional data is needed or data verification is required. De-identified data will be uploaded to the aggregate data within REDCap which will allow for aggregation among all the sites. Data Collection The blood draws will occur via the clinical staff. The current order set has blood draws at a minimum of every 6 hours (0, 6, 12, 18, 24). Additional lab studies are likely to be added based on how critical the patient. The investigators will modify the order set to include blood draws at 0, 3, 6, 12, 18, 24. The investigators will need a green top tube for the ionized calcium which is \<5mL per tube and the drawn tube will have multiple uses (e.g. metabolic panels, alcohol levels, etc.). Additional ionized calcium studies may be ordered solely at the discretion of the attending clinician and will be included in the analysis. . With regards to the clinical data, the investigators plan to capture the data after clinical care has occurred and includes the following: Demographics Injury Severity Scores Timing- date and time of injury, EMS arrival time, air transport arrival time, transferring center arrival time, trauma center arrival time Blood products infusion Laboratory Studies Medications Procedures Vital Signs Prehospital Medications Hospital Medications Imaging Studies Blood products and fluids Outcome data- discharge status, time to death, ventilator days, intensive care unit days, hospital days, discharge location, total blood products and fluids received, cardiac events Data analysis The investigators will primarily use descriptive and inferential statistics along with regression modeling. Significance for results will be established when p-values are less than 0.05. Categorical Data will be summarized using percentages and Chi-Squared tests or Fisher's exact test where appropriate. Means and standard deviations or medians and interquartile ranges will be used as summary statistics for continuous variables, and they will be analyzed using Student's t-test and ANOVA or Wilcoxon's Test where appropriate. Data may be log-transformed for normalization. The data analyst will use Discrete-Time (eg. Complementary Log-Log) or Cox Proportional Hazards to assess associations between baseline and time-dependent covariates with time-to-hypocalcemia. Treatment variables, such as blood product transfusion, will be measured at time-dependent covariates. Cox Proportional Hazards models will be used to assess associations between baseline covariates, time-dependent covariates (treatments and hypocalcemia), and mortality. The data analyst and investigators will analyze data using relevant statistical software including SAS (v9.4, Cary, North Carolina), JMP Statistical Discovery (v15, Cary, North Carolina), Microsoft Excel (v360, Redmond, Washington).