Pre-hospital thoracotomy

The London Helicopter Emergency Medical Service provides a physician / paramedic team to victims of trauma. One of the interventions performed by their physicians is pre-hospital resuscitative thoracotomy to patients with cardiac arrest due to penetrating thoracic trauma. They have published the outcomes from this procedure over a 15 year period which show an 18% survival to discharge rate, with a high rate of neurologically intact survivors1.

The article was submitted for publication on February 1, 2010, and in the discussion mentions a further two survivors from the procedure performed after conducting the study. It is likely therefore in the year and a half since submission still more patients have been saved. It will be interesting to read future reports from this team as the numbers accumulate; penetrating trauma missions are sadly increasing in frequency.

Having worked for these guys and performed this procedure in the field a few times myself, I can attest to the training and governance surrounding this system. The technique of clamshell thoracotomy is well described 2 and one I would recommend for the non-surgeon.

BACKGROUND: Prehospital cardiac arrest associated with trauma almost always results in death. A case of survival after prehospital thoracotomy was published in 1994 and several others have followed. This article describes the result of prehospital thoracotomy in a physician-led system for patients with stab wounds to the chest who suffered cardiac arrest on scene.

METHODS: A 15-year retrospective prehospital trauma database review identified victims of stab wounds to the chest who suffered cardiac arrest on scene and had thoracotomy performed according to local standard operating procedures.

RESULTS: Overall, 71 patients met inclusion criteria. Thirteen patients (18%) survived to hospital discharge. Neurologic outcome was good in 11 patients and poor in 2. Presenting cardiac rhythm was asystole in four patients, pulseless electrical activity in five, and unrecorded in the remaining four. All survivors had cardiac tamponade. The medical team was present at the time of cardiac arrest for six survivors (good neurologic outcome): arrived in the first 5 minutes after arrest in three patients (all good neurologic outcome), arrived 5 minutes to 10 minutes after arrest in two patients (one poor neurologic outcome), and in one patient (poor neurologic outcome) the period was unknown. Of the survivors, seven thoracotomies were performed by emergency physicians and six by anesthesiologists.

CONCLUSIONS: Prehospital thoracotomy is a well-established procedure in this physician-led prehospital service. Results from this and other similar systems suggest that when performed for the subgroup of patients described, significant numbers of survivors with good neurologic outcome can be expected.

1. Thirteen Survivors of Prehospital Thoracotomy for Penetrating Trauma: A Prehospital Physician-Performed Resuscitation Procedure That Can Yield Good Results
J Trauma. 2011 May;70(5):E75-8

2. Emergency thoracotomy: “how to do it”
Emerg Med J. 2005 January; 22(1):22–24
Full text available here

Exsanguinating cardiac arrest not always fatal

The British Military has developed a reputation for aggressive pre-hospital critical care including (but not limited to) the use of blood products and tourniquets, and coordinated field hospital trauma care. They now report the outcomes for patients with traumatic cardiac arrest, mainly from improvised explosive devices. Of 52 patients, 14 (27%) demonstrated return of spontaneous circulation (ROSC), of whom four (8%) survived to hospital discharge with a neurologically good recovery. Resuscitative thoracotomy (RT) was performed on 12 patients (8 in the ED), including all four survivors. RT enabled open-chest CPR, release of pericardial tamponade, lung resection and compression of the descending thoracic aorta for haemorrhage control.
No patients who arrested in the field survived, although one of the neurologically well-recovered survivors arrested during transport to hospital and was in cardiac arrest for 24 minutes. The authors propose this individual’s survival was in part due to ‘the high level of care that he received during retrieval, including haemorrhage control, tracheal intubation and transfusion of blood products‘.
Asystole was universally associated with death but agonal / bradycardic rhythms were not. In keeping with other studies, cardiac activity on ultrasound was associated with ROSC.

AIM: To determine the characteristics of military traumatic cardiorespiratory arrest (TCRA), and to identify factors associated with successful resuscitation.

METHODS: Data was collected prospectively for adult casualties suffering TCRA presenting to a military field hospital in Helmand Province, Afghanistan between 29 November 2009 and 13 June 2010.

RESULTS: Data was available for 52 patients meeting the inclusion criteria. The mean age (range) was 25 (18-36) years. The principal mechanism of injury was improvised explosive device (IED) explosion, the lower limbs were the most common sites of injury and exsanguination was the most common cause of arrest. Fourteen (27%) patients exhibited ROSC and four (8%) survived to discharge. All survivors achieved a good neurological recovery by Glasgow Outcome Scale. Three survivors had arrested due to exsanguination and one had arrested due to pericardial tamponade. All survivors had arrested after commencing transport to hospital and the longest duration of arrest associated with survival was 24min. All survivors demonstrated PEA rhythms on ECG during arrest. When performed, 6/24 patients had ultrasound evidence of cardiac activity during arrest; all six with cardiac activity subsequently exhibited ROSC and two survived to hospital discharge.

CONCLUSION: Overall rates of survival from military TCRA were similar to published civilian data, despite military TCRA victims presenting with high Injury Severity Scores and exsanguination due to blast and fragmentation injuries. Factors associated with successful resuscitation included arrest beginning after transport to hospital, the presence of electrical activity on ECG, and the presence of cardiac movement on ultrasound examination.

Outcomes following military traumatic cardiorespiratory arrest: A prospective observational study
Resuscitation. 2011 Sep;82(9):1194-7

Trauma mortality and systolic BP

Here’s some further evidence that a ‘lowish’ – as opposed to a low – systolic blood pressure is a reason to be vigilant in trauma. In this study, it was BP measurement in the ED (rather than pre-hospital) that was assessed:

Introduction: Non-invasive systolic blood pressure (SBP) measurement is often used in triaging trauma patients. Traditionally, SBP < 90 mmHg has represented the threshold for hypotension, but recent studies have suggested redefining hypotension as SBP < 110 mmHg. This study aims to examine the association of SBP with mortality in blunt trauma patients.

Methods: This is an analysis of prospectively recorded data from adult (≥16 years) blunt trauma patients. Included patients presented to hospitals belonging to the Trauma Audit and Research Network (TARN) between 2000 and 2009. The primary outcome was the association of SBP and mortality rates at 30 days. Multivariate logistic regression models were used to adjust for the influence of age, gender, Injury Severity Score (ISS) and Glasgow Coma Score (GCS) on mortality.

Results: 47,927 eligible patients presented to TARN hospitals during the study period. Sample demographics were: median age: 51.1 years (IQR=32.8–67.4); male 60% (n=28,694); median ISS 9 (IQR = 8–10); median GCS 15 (IQR = 15–15); and median SBP 135 mmHg (IQR = 120–152). We identified SBP < 110 mmHg as a cut off for hypotension, where a significant increase in mortality was observed. Mor- tality rates doubled at <100 mmHg, tripled at <90 mmHg and were 5- to 6-fold at <70 mmHg, irrespective of age.

Conclusion: We recommend triaging adult blunt trauma patients with a SBP < 110 mmHg to resuscitation areas within dedicated trauma units for close monitoring and appropriate management.

Systolic blood pressure below 110mmHg is associated with increased mortality in blunt major trauma patients: Multicentre cohort study
Resuscitation. 2011 Sep;82(9):1202-7

Score to predict traumatic coagulopathy

Acute traumatic coagulopathy (ATC) is present in up to 25% of major trauma patients by the time they arrive in hospital. A predictive tool called the coagulopathy of severe trauma (COAST) score was retrospectively derived and then prospectively validated in major trauma patients in the state of Victoria, Australia. The definition of ATC was INR > 1.5 (1.0–1.3) or aPTT of > 60 s (25–38 s) on hospital presentation.

The study claims that a subgroup of patients with acute traumatic coagulopathy can be accurately identified based on simple observations in the pre-hospital phase or immediately on presentation to the ED, and that this could improve the feasibility of prospective interventional studies. Perhaps this will lead on to evaluation of pre-hospital tranexamic acid or even blood products?

At the cutoff score of ≥3, 40 coagulopathic patients would have been missed with 60 patients correctly predicted. The authors argue that while the low sensitivity of the score missed these coagulopathic patients, they had significantly better outcomes (and contained a significantly higher proportion of patients with isolated severe head injury).

Introduction: The inability to accurately predict acute traumatic coagulopathy (ATC) has been a key factor in the low level of evidence guiding its management. The aim of this study was to develop a tool to accurately identify patients with ATC using pre-hospital variables without the use of pathology or radiological testing.

Methods: Retrospective data from the trauma registry on major trauma patients were used to identify vari- ables independently associated with coagulopathy. These variables were clinically evaluated to develop a scoring system to predict ATC, which was prospectively validated in the same setting.

Results: There were 1680 major trauma patients in the derivation dataset, with 151 patients being coagulopathic. Pre-hospital variables independently associated with ATC were entrapment (OR 1.85; 95% CI: 1.12–3.06), temperature (OR 0.60; 95% CI: 0.60–0.72), systolic blood pressure (OR 0.99; 95% CI: 0.98–0.99), abdominal or pelvic content injury (OR 2.0; 95% CI: 1.27–3.12) and pre-hospital chest decompression (OR 4.99; 2.77–8.99). The COAST score was developed, scoring points for entrapment, temperature <35 ◦ C, systolic blood pressure <100 mm Hg, abdominal or pelvic content injury and chest decompression. Prospectively validated using 1225 major trauma patients, a COAST score of ≥3 had a specificity of 96.4% with a sensitivity of 60.0%, with an area under the receiver operating characteristic curve of 0.83 (0.78–0.88).

Conclusions: The COAST score accurately identified a group of patients with ATC using pre-hospital obser- vations. This predictive tool can be used to select patients for inclusion into prospective studies examining management options for ATC. Mortality in these patients is high, potentially improving feasibility of outcome studies.

Still no cardiac arrest survival benefit from epinephrine?

A double blind randomised controlled trial showed significantly better rates of return of spontaneous circulation and hospital admission with the use of adrenaline (epinephrine) compared with placebo. This effect was observed with both shockable and non-shockable initial cardiac arrest rhythms. There was no statistically significant difference in the primary outcome of survival to hospital discharge.

Interesting but unfortunate political factors appear to have prevented recruitment to the required numbers of patients for this study so it is underpowered for its primary outcome of survival to hospital discharge, which in the adrenaline group was double that in the placebo group, although this did not reach statistical significance. What was supposed to be a multi-centre study became a single centre one and it was not possible to continue as the study drugs reached their expiry date and no additional funding was available.

So do ROSC and survival to admission matter? The authors make the following point:

While not the primary outcome of our study, ROSC is an increasingly important clinical endpoint as the influence of post resuscitation care interventions (i.e.: therapeutic hypothermia, managing underlying cause, organ perfusion and oxygenation) on survival to hospital discharge are recognised.

Optimum dose and timing of adrenaline remain unknown, along with whether it impacts on long-term outcomes.

BACKGROUND: There is little evidence from clinical trials that the use of adrenaline (epinephrine) in treating cardiac arrest improves survival, despite adrenaline being considered standard of care for many decades. The aim of our study was to determine the effect of adrenaline on patient survival to hospital discharge in out of hospital cardiac arrest.

METHODS: We conducted a double blind randomised placebo-controlled trial of adrenaline in out-of-hospital cardiac arrest. Identical study vials containing either adrenaline 1:1000 or placebo (sodium chloride 0.9%) were prepared. Patients were randomly allocated to receive 1ml aliquots of the trial drug according to current advanced life support guidelines. Outcomes assessed included survival to hospital discharge (primary outcome), pre-hospital return of spontaneous circulation (ROSC) and neurological outcome (Cerebral Performance Category Score – CPC).

RESULTS: A total of 4103 cardiac arrests were screened during the study period of which 601 underwent randomisation. Documentation was available for a total of 534 patients: 262 in the placebo group and 272 in the adrenaline group. Groups were well matched for baseline characteristics including age, gender and receiving bystander CPR. ROSC occurred in 22 (8.4%) of patients receiving placebo and 64 (23.5%) who received adrenaline (OR=3.4; 95% CI 2.0-5.6). Survival to hospital discharge occurred in 5 (1.9%) and 11 (4.0%) patients receiving placebo or adrenaline respectively (OR=2.2; 95% CI 0.7-6.3). All but two patients (both in the adrenaline group) had a CPC score of 1-2.

CONCLUSION: Patients receiving adrenaline during cardiac arrest had no statistically significant improvement in the primary outcome of survival to hospital discharge although there was a significantly improved likelihood of achieving ROSC.

Effect of adrenaline on survival in out-of-hospital cardiac arrest: A randomised double-blind placebo-controlled trial
Resuscitation. 2011 Sep;82(9):1138-43