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We take a break from our regularly scheduled CriticalCareNow “Vitals” content to dive deeper into a topic previously covered on this site. But don’t worry, we’ll be back with more critical care fundamentals next Friday!
Pre-brief:
In a previous post, we covered the basics of trauma-induced coagulopathy (TIC). This condition is influenced by a long list of factors, including the Lethal Triad (Diamond?) of Trauma, dilution of blood products by crystalloids, severe tissue injury, and others. TIC is usually diagnosed with laboratory evaluation, including the elusive thromboelastography. But what if we could identify which patients have TIC right at the site of injury before we even begin medical treatment?
Article: Gaessler, Holger MD; Helm, Matthias PhD, MD; Kulla, Martin PhD, MD; Hossfeld, Bjoern MD; Schmid, Uta MD; Kerschowski, Juergen MD; Bretschneider, Ingeborg MD Prehospital evaluation and detection of induced coagulopathy in trauma: The PREDICT study, Journal of Trauma and Acute Care Surgery: August 2021 – Volume 91 – Issue 2 – p 344-351 doi: 10.1097/TA.0000000000003246. PMID: 34397955.
What did they do?
- Single-center, prospective, observational study
- August 2015 to February 2018
- Population
- Inclusion
- All injured patients who were medically treated by the Helicopter EMS Christoph 22, Ulm, and transported to one of the two level 1 trauma centers at Ulm, Germany
- HEMS Christoph 22 is deployed within a radius of 70km
- Pilot, EMS physician, and paramedic team
- No blood or coagulation products were available for prehospital treatment during the study period
- All severities of injury included
- All injured patients who were medically treated by the Helicopter EMS Christoph 22, Ulm, and transported to one of the two level 1 trauma centers at Ulm, Germany
- Exclusion
- Younger than 18 years
- Pregnant women
- Patients with preexisting coagulation disorders or receiving coagulation-influencing drugs in long-term therapy
- Patients who had already received TXA from ground EMS
- Time interval between prehospital blood sampling and ROTEM assay of >120 minutes
- Inclusion
- Intervention
- On arrival of HEMS crew, the first blood sample was taken from the patient (as long as it did not delay urgent treatment). Samples obtained for:
- Blood gas analysis (transported in a thermo-insulated sample container with ice water)
- ROTEM
- Plasma coagulation analysis
- Patient was then transported to the hospital and all vital signs and treatments were documented
- On arrival at the ED, another blood sample was obtained for the same tests; again, vitals of the patient, treatments given, and medications administered in the ED were documented.
- After 28 days, final data collection was performed and included:
- Hospital discharge diagnoses
- Discharge status
- Survival until hospital discharge or 28-day survival
- On arrival of HEMS crew, the first blood sample was taken from the patient (as long as it did not delay urgent treatment). Samples obtained for:
- Outcomes
- Primary: Detection of early coagulopathy after trauma
- Secondary:
- TIC-associated changes in blood gas analyses
- Transfusion requirement
- 28-day mortality in patients with TIC and Hyperfibrinolysis (HF)
- Estimated sample of 150 to 200 patients to provide 80% power, two-sided significance level of 5%
- Performed a subgroup analysis of patients with TICCS of at least 10 points
Results
- 194 patients with 46 exclusions → 148 patients ultimately enrolled in the study
- Mean age 45+/-19 years, 76.4% male; both age and sex were equally matched across the groups (no coagulopathy vs TIC vs TIC & HF)
- Mean ISS 22.1+/-17.1
- Time between trauma and first blood sample was approximately equal in all groups
- Average 28-day mortality was 7.4%
- 24.3% (36/146) had a TIC with changes in EXTEM and FIBTEM
- 6.1% (9/146) had hyperfibrinolysis as well (TIC and HF)
- 21 patients had TICCS≥10 points
- 10/21 showed a TIC at T0
- 6/21 had hyperfibrinolysis
- Similar amounts of crystalloids infused at the scene, but statistically significant differences in colloids infused (TIC and HF and TICCS≥10 subgroup had more colloid used)
- Here are the data highlights (just a subset of the data presented in the original paper; yellow boxes indicate statistically significant differences):
- ROTEM parameters also had significant between-group differences that mirrored the data shown above.
Strengths
- Prospective study in which only 7 patients had incomplete data sets. Prospective studies minimize bias and allow for better assessment for correlations.
- To date, this is the largest study evaluating TIC in the prehospital setting with 148 subjects. This was based on a rudimentary search of the literature, so leave a comment below if you found a larger study!
- Mean ISS was 22.1, representative of a fairly sick cohort of patients. This seems pretty representative of a level 1 trauma center.
- Study looked at a great patient-oriented outcome (POO): 28-day mortality rate.
- Investigators evaluated a subgroup of patients with potential for higher injury severity (TICCS≥10).
Limitations
- Single-center study of patients treated by a single HEMS unit. The external validity of the conclusions must be tested in studies that evaluate other settings.
- Study population was not large enough to allow for detailed subgroup analyses.
- As would be expected, blood collection was second priority to medical treatment. Patients, in whom the blood withdrawal could not be performed promptly, were excluded from the study.
- As an observational trial, we can only draw conclusions about correlation and not causation.
- There is no discussion about the use of colloids and statistically significant differences in the volume administered. Recent publications have called into question the benefits of using colloids in the acute phase of trauma resuscitation.
Discussion
This study really sets the stage with regards to establishing that trauma-induced coagulopathy and hyperfibrinolysis can occur at the site of injury, even before massive resuscitation efforts begin. This first step paves the way to discovering how we can impact patient care in the prehospital setting. The investigators evaluated a subgroup of patients with a TICCS of 10 or higher. Out of these patients, about half had TIC even before major resuscitation had begun. As demonstrated by numerous other studies, TIC is certainly influenced by and associated with higher levels of injury severity. While this certainly gives us valuable information, I would have liked to see a graphical relationship between TIC/HF vs TICCS for each individual score.
The authors did not address the association of low hemoglobin and low heart rate with TIC and HF. In patients who are acutely bleeding, the hemoglobin should stay relatively stable until crystalloids are administered. While the higher volume of colloids infused in these groups may account for the difference in hemoglobin, it is odd that the TIC and HF group have a significantly lower hemoglobin level as compared to patients without hyperfibrinolysis. Perhaps these patients had lower hemoglobin levels before the accident? Perhaps the baseline low hemoglobin alone has an association with hyperfibrinolysis? In a similar vein, heart rate would be expected to rise in hypovolemic shock. Perhaps the patients in this group were more likely to be on medications that impede the normal elevation in heart rate due to exsanguination? Unfortunately, we can’t answer these questions from this study alone.
Author’s Conclusion
In severely injured patients, TIC and HF can already be present at the site of incidence and do not only develop during medical treatment and transport. Significant changes in blood gas analysis parameters are associated with the presence of HF at the incidence site. In patients with TICCS of ≥10 points, TIC and HF are significantly more frequent. Future studies should investigate the predictive value of prehospital blood gas parameters and TICCS in terms of TIC and HF.
Our Conclusion
This study, with a moderately-sized subject population, demonstrated that patients with trauma-induced coagulopathy and hyperfibrinolysis can be identified at the site of injury. We look forward to seeing future studies that investigate the clinical impact of this information and how we can help more patients in the prehospital setting.
References
- Gaessler H, Helm M, Kulla M, Hossfeld B, Schmid U, Kerschowski J, Bretschneider I. Prehospital evaluation and detection of induced coagulopathy in trauma: The PREDICT study. J Trauma Acute Care Surg. 2021 Aug 1;91(2):344-351. doi: 10.1097/TA.0000000000003246. PMID: 34397955.
