Fluid Resuscitation Optimization in Surgical Trauma Patients (FROST)

The aim of this study is to determine if the incidence of post-operative complications can be decreased by the implementation of intra-operative, minimally invasive hemodynamic monitoring (MIHM) via FloTrac™ and EV1000™ in trauma patients.

Numerous factors are known to contribute to post-traumatic morbidity and mortality. Acute blood loss, hypovolemia, and systemic inflammatory response syndrome can often develop following severe traumatic injury and are, frequently, further exacerbated by the presence of pre-existing health conditions. The culmination of these insults and/or pre-existing conditions can precipitate an imbalance in oxygen delivery and consumption leading to tissue ischemia and resultant organ dysfunction.

Tissue ischemia precipitates a disruption in the balance of oxygen delivery and consumption often yielding a conversion from aerobic to anaerobic processes in order to maintain metabolic functionality. The conversion to anaerobic processes leads to the production of lactic acid and a resulting consumption of the body's basic buffers. Clinically, the consumption of the body's basic buffers is frequently referred to as the development of a base deficit. Both the production of lactic acid and the development of a base deficit have been positively linked to the increased morbidity and mortality in multiple critically ill patient populations, including those with traumatic injuries.

Multiple studies have linked the rate at which base deficit corrects or lactic acid clears to the likelihood of survival. Accordingly, hemodynamic monitoring can provide vital information concerning cardiovascular function including vascular volume, vascular capacitance, and cardiac performance. Obtaining this information enables clinicians to tailor interventions to target specific components of the cardiovascular system in order to most effectively reverse the cause of tissue hypoxia, elevation in lactic acid, and base deficit, while simultaneously decreasing the likelihood of causing harm through unnecessary or unwarranted changes in management.

Advancements in hemodynamic monitoring technology now allow clinicians to obtain data by using minimally invasive techniques. Devices utilizing this technology can be connected to vascular access routinely utilized in the intensive care setting such as arterial lines. These devices provide parameters such as systolic pressure variation (SPV), pulse pressure variation (PPV) and stroke volume variation (SVV) to predict fluid responsiveness of critically ill, mechanically ventilated patients. Studies evaluating these parameters have shown them to have a 84-94% positive predictive value for fluid responsiveness. In addition, higher variability in studied parameters were indicative of patients who were more likely to be responsive to fluid challenges.

Modern clinical management in critically ill patients with cardiovascular dysfunction hinges on reversal of the underlying cause of cardiovascular dysfunction. Recent management strategies have used a multi-faceted approach in which multiple processes of potential dysfunction can be monitored and managed simultaneously. Management is goal directed with clearly defined endpoints for the management of vascular volume, cardiac performance as well as maintenance of vascular capacitance. Hemodynamic monitoring technology is essential in providing data that will allow clinical interventions to be tailored to patient-specific physiology and provide goals for titration of therapy.

In recent years, data has emerged using goal directed therapy in the surgical patient population with favorable outcomes suggesting a decrease in post-operative organ dysfunction, ICU and hospital length of stay, however, there is limited data in the trauma patient population. This study endeavors to determine if the implementation of intra-operative monitoring will decrease the incidence of post-operative complications such as acute lung injury, infections, thromboembolism, cerebral vascular accident, acute kidney injury, myocardial infarction; in addition to the traditional outcome measures of mortality and length of stay.

Eligibility Criteria:
Inclusion Criteria:

1. 18 years of age or older
2. Injury Severity Score \> 15 (indicator of anticipated trauma mortality)
3. Admission to Surgical-Trauma ICU (STICU)
4. Anticipated surgery within 72 hours of admission
5. American Society of Anesthesiology patient classification status (ASA) 2-5
6. Lactic acid \> 2.5 within 24 hours of surgical procedure or Base deficit ≥ - 5 mmol/L, or persistent requirement for vasopressor support within 24 hours of surgical procedure
7. Patient requires mechanical ventilation prior to consenting surgery
8. Vascular devices that include a minimum of an arterial line
9. Minimally invasive hemodynamic monitoring initiated prior to first surgical procedure unless patient is taken emergently, e.g. OR from trauma bay
10. Patients requiring emergent initial operative procedures will be eligible for consenting if above criteria are met prior to their second surgical procedure
11. Anticipated operative procedure precipitating evaluation and/or consenting for study must be \> 30 minutes in duration

    * Procedures \< 30 minutes would not result in significant metabolic stress necessitating a continuation of MIHM

Exclusion Criteria:

1. Pregnancy
2. Exclusions due to limitations with respect to accuracy of MIHM:

   * Patients not intubated prior to surgical procedure
   * Patients requiring an open thoracotomy
   * Patients with known history of surgical intervention for peripheral vascular disease
   * Patients with pre-existing atrial arrhythmias
   * Patients who are on cardiopulmonary bypass
3. Isolated acute cerebral injury and/or traumatic cerebral injury

   * Hemodynamic management in this patient population does not always follow typical/standard endpoints due to nuances of managing intracranial pressures
4. Cardiac arrest prior to enrollment
5. Patients with pre-existing, dialysis dependent, renal failure upon admission

   * Hemodynamic management in this patient population does not always follow typical/standard endpoints due to nuances of managing renal failure
6. Patients with pre-existing cirrhosis

   * Hepatic failure results in abnormal clearance of lactic acid
7. Patients with no survival injuries, e.g. gunshot wound to the head