Brain Injury Associated Shock: An Under-Recognized and Challenging Prehospital Phenomenon.

OBJECTIVE: Hemodynamic collapse in multi-trauma patients with severe traumatic brain injury (TBI) poses both a diagnostic and therapeutic challenge for prehospital clinicians. Brain injury associated shock (BIAS), likely resulting from catecholamine storm, can cause both ventricular dysfunction and vasoplegia but may present clinically in a manner similar to hemorrhagic shock. Despite different treatment strategies, few studies exist describing this phenomenon in the early post-injury phase. This retrospective observational study aimed to describe the frequency of shock in isolated TBI in prehospital trauma patients and to compare their clinical characteristics to those patients with hemorrhagic shock and TBI without shock. METHODS: All prehospital trauma patients intubated by prehospital medical teams from New South Wales Ambulance Aeromedical Operations (NSWA-AO) with an initial Glasgow Coma Scale (GCS) of 12 or less were investigated. Shock was defined as a pre-intubation systolic blood pressure under 90mmHg and the administration of blood products or vasopressors. Injuries were classified from in-hospital computed tomography (CT) reports. From this, three study groups were derived: BIAS, hemorrhagic shock, and isolated TBI without shock. Descriptive statistics were then produced for clinical and treatment variables. RESULTS: Of 1,292 intubated patients, 423 had an initial GCS of 12 or less, 24 patients (5.7% of the original cohort) had shock with an isolated TBI, and 39 patients had hemorrhagic shock. The hemodynamic parameters were similar amongst these groups, including values of tachycardia, hypotension, and elevated shock index. Prehospital clinical interventions including blood transfusion and total fluids administered were also similar, suggesting they were indistinguishable to prehospital clinicians. CONCLUSIONS: Hemodynamic compromise in the setting of isolated severe TBI is a rare clinical entity. Current prehospital physiological data available to clinicians do not allow for easy delineation between these patients from those with hemorrhagic shock.

Factors Associated With Desaturation in Prehospital Rapid Sequence Intubation in a Helicopter Emergency Medical Service.

OBJECTIVE: Desaturation during prehospital rapid sequence intubation (RSI) is common and is associated with patient morbidity. Past studies have identified oxygen saturations at induction, the grade of laryngoscopy, and multiple attempts to intubate as being associated with desaturation. This study aimed to investigate whether there are other factors, identifiable before RSI, associated with desaturation. METHODS: This was a study of a physician-paramedic critical care team operating as Aeromedical Operations, NSW Ambulance. Prehospital RSIs (using paralysis) were studied retrospectively via patient case notes, monitor data, and an airway database. The review occurred between April 1, 2016, and December 31, 2018. Desaturation was defined as monitor recordings of saturations ≤ 92%. Logistic regression was performed for factors likely to be associated with desaturation. RESULTS: Desaturation occurred in 67 of 350 (19.1%) RSIs. Factors significantly associated with desaturation included male sex, a chest injury, increased weight, and lower saturations pre-RSI. CONCLUSION: Increased weight, chest injuries, and lower oxygen saturations are associated with desaturation at RSI. The variable male sex may be a surrogate for other as-yet unidentified factors.

Clinical outcomes of traumatic pneumothoraces undergoing conservative management following detection by prehospital physicians.

OBJECTIVE: To describe the clinical and transport characteristics of patients diagnosed with a suspected traumatic pneumothorax and managed conservatively by prehospital medical teams including secondary deterioration during transfer and the subsequent rate of in-hospital tube thoracostomy. METHODS: Retrospective observational study of all adult trauma patients diagnosed with a suspected pneumothorax on ultrasound and managed conservatively by their treating prehospital medical team between 2018 and 2020. Descriptive analysis was performed comparing patients who did and did not receive in-hospital tube thoracostomy. RESULTS: In total, 181 patients were diagnosed with suspected traumatic pneumothoraces on prehospital ultrasound of which 75 (41.4%) were managed conservatively by their treating medical team whilst 106 (58.6%) underwent pleural decompression. There were no recorded cases of emergent pleural decompression required in transit. Of the 75 conservatively managed patients, 42 (56%) had an intercostal catheter (ICC) placed within four hours of hospital arrival and another nine (17.6%) had an ICC placed between four- and 24-hours post-hospital arrival. There was no significant difference in prehospital clinical characteristics between patients who did and did not receive an in-hospital ICC. The detection of a pneumothorax on the initial chest x-ray and larger pneumothorax volume visualised on computed tomography imaging were significantly more common in patients receiving in-hospital ICCs. Aviation factors including flight altitude and duration of flight were not associated with subsequent in-hospital tube thoracostomy. CONCLUSION: Prehospital medical teams can safely identify patients who have a traumatic pneumothorax and can be transported to hospital without pleural decompression. Patient characteristics at the time of hospital arrival combined with the size of pneumothorax identified on imaging appear most likely to influence subsequent urgent in-hospital tube thoracostomy placement.

Serratus Anterior Plane Block for Clinically Suspected Rib Fractures in Prehospital and Retrieval Medicine.

Objective: To describe the use of the serratus anterior plane block (SAPB) in the prehospital and retrieval environment including the ability to accurately identify those patients with thoracic trauma and clinically suspected rib fractures who would benefit from this procedure.Methods: This is a retrospective case series of all patients with thoracic trauma and clinically suspected rib fractures who received SAPB by a prehospital and retrieval medical team in New South Wales, Australia, between 2018 and 2021. The primary outcome was to identify the proportion of patients who received appropriate blocks based on the criteria of reporting moderate pain after receiving adequate pre-block analgesia. Secondary outcomes included the proportions of patients with rib fractures identified on thoracic imaging, concomitant time-critical pathology, radiologist identification of fluid adjacent to the serratus anterior muscle, and local anesthetic systemic toxicity.Results: Of the 2004 patients who sustained thoracic trauma, only 13 received a SAPB. Nine (69.2%) met the predetermined definition of appropriate selection. Of the four patients who did not meet this criteria, three reported less than moderate pain and one did not receive adequate pre-block analgesia. There was no significant effect on median scene interval when compared to other thoracic trauma patients who did not receive a SAPB. Ten patients had rib fractures identified on in-patient imaging (chest x-ray or computed tomography (CT)) with a median (IQR) number of ribs fractured of 5 (interquartile range 2-10). Three of these patients had radiological flail segments. Prespecified time-critical pathology was identified in three patients (23.1%) on initial hospital imaging. Five out of eight patients with post-SAPB CT imaging (62.5%) available for radiologist review had fluid identified adjacent to the serratus anterior muscle. None of the 13 patients had local anesthetic systemic toxicity.Conclusion: The SAPB can be safely and successfully performed in the prehospital and retrieval environment, where clinicians can appropriately identify patients with thoracic trauma and clinically suspected rib fractures who would benefit from this technique. Further research is required to identify the ideal patient population to perform the SAPB upon and compare its performance to current analgesic options.

A multicenter evaluation of the accuracy of prehospital eFAST by a physician-staffed helicopter emergency medical service.

PURPOSE: The purpose of this study is to report the relative accuracy of prehospital extended focused assessment with sonography in trauma (eFAST) examinations performed by HEMS physicians. METHODS: Trauma patients who received prehospital eFAST by HEMS clinicians between January 2013 and December 2017 were reviewed. The clinician's interpretations of these ultrasounds were compared to gold standard references of CT imaging or operating room findings. The outcomes measured include the calculated accuracy of eFAST for detecting intraperitoneal free fluid (IPFF), pneumothorax, hemothorax, and pericardial fluid compared to available gold standard results. RESULTS: Of the 411 patients with adequate data for comparison, the median age was 39.5 years with 73% male and 98% sustaining blunt force trauma. For the detection of IPFF, eFAST had a sensitivity of 25% (95% CI 16-36%) and specificity of 96% (95% CI 93-98%). Sensitivities and specificities were calculated for pneumothorax (38% and 96% respectively), hemothorax (17% and 97% respectively), and pericardial effusion (17% and 100% respectively). These results did not change significantly when reassessed with several sensitivity analyses. CONCLUSION: Prehospital eFAST is reliable for detecting the presence of intraperitoneal free fluid. This finding should inform receiving trauma teams to prepare for early definitive care in these patients. The low sensitivities across all components of the eFAST highlight the importance of cautiously interpreting negative studies while prompting the need for further studies. TRIAL REGISTRATION: ACTRN12618001973202 (Registered on 06/12/2018).