Increased survival for resuscitated Utstein-comparator group patients conveyed directly to cardiac arrest centres in a large rural and suburban population in England.

AIM: The cohort of patients in which cardiac arrest centres (CAC) in rural and suburban populations confer the greatest survival benefit remains unclear. The aim of this study was to assess whether the transfer of resuscitated Utstein-comparator out-of-hospital cardiac arrest (OHCA) patients direct to a CAC was associated with improved survival to hospital discharge compared to patients conveyed to non-specialist centres. METHODS: A consecutive sample of adult (≥18 years old) Utstein-comparator patients (witnessed collapse and initial shockable rhythm) were included from the East of England Ambulance Service NHS Trust Utstein resuscitation registry; 2018-2022. Logistic regression was used to compare survival to discharge in patients transported to CACs compared with patients transported to non-specialist centres. RESULTS: During the study period, resuscitation was attempted in 18,276 OHCA patients. N = 2448 (13.4%) met the Utstein-comparator definition and 1151 patients were included in the final analysis; per protocol. Survival was greater for patients conveyed directly to a CAC (n = 768, 60.7%) compared to non-specialist centres (n = 383, 47.3%); adjusted OR 1.44 (95%CI 1.07-1.94),p = 0.017. Amongst the centres analysed in this study, there was significant inter-hospital variability in survival between CACs (p = 0.017). There was no association between patient volume and survival (p = 0.850). CONCLUSION: Direct transport to a cardiac arrest centre was associated with a 44% increase in the odds of survival compared to conveyance to a non-specialist centre for resuscitated adult patients presenting with witnessed collapse and initial shockable OHCA rhythm.

The Efficacy of Whole Blood Resuscitation During Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) to Mitigate Post-occlusion Circulatory Collapse: A Translational Model in Large Swine.

INTRODUCTION: Uncontrolled torso hemorrhage is the primary cause of potentially survivable deaths on the battlefield. Zone 1 Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA), in conjunction with damage control resuscitation, may be an effective management strategy for these patients in the prehospital or austere phase of their care. However, the effect of whole blood (WB) transfusion during REBOA on post-occlusion circulatory collapse is not fully understood. MATERIALS AND METHODS: Yorkshire male swine (n = 6 per group, 70-90 kg) underwent a 40% volume-controlled hemorrhage. After a 10-minute hemorrhagic shock period, a REBOA balloon was inflated in Zone 1. Fifteen minutes after inflation, 0, 1, or 3 units (450 mL/unit) of autologous WB was infused through the left jugular vein. Thirty minutes after initial balloon inflation, the balloon was deflated slowly over 3 minutes. Following deflation, normal saline was administered (up to 3,000 mL) and swine were observed for 2 hours. Survival (primary outcome), hemodynamics, and blood gas values were compared among groups. Statistical significance was determined by log-rank test, one-way ANOVA, and repeated measures ANOVA. RESULTS: Survival rates were comparable between groups (P = .345) with 66% of control, 33% of the one-unit animals, and 50% of the 3-unit animals survived until the end of the study. Following WB infusion, both the 1-unit and the 3-unit groups had significantly higher blood pressure (P < .01), pulmonary artery pressure (P < .01), and carotid artery flow (P < .01) compared to the control group. CONCLUSIONS: WB transfusion during Zone 1 REBOA was not associated with increased short-term survival in this large animal model of severe hemorrhage. We observed no signal that WB transfusion may mitigate post-occlusion circulatory collapse. However, there was evidence of supra-normal blood pressures during WB transfusion.

The association between prehospital post-return of spontaneous circulation core temperature and survival after out-of-hospital cardiac arrest.

BACKGROUND AND IMPORTANCE: Following the return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest (OHCA), a low body temperature on arrival at the hospital and on admission to the ICU is reportedly associated with increased mortality. Whether this association exists in the prehospital setting, however, is unknown. OBJECTIVE: The objective of this study was to investigate whether the initial, prehospital core temperature measured post-ROSC is independently associated with survival to hospital discharge in adult patients following OHCA. DESIGN, SETTING AND PARTICIPANTS: This retrospective observational study was conducted at East Anglian Air Ambulance, a physician-paramedic staffed Helicopter Emergency Medical Service in the East of England, UK. Adult OHCA patients attended by East Anglian Air Ambulance from 1 February 2015 to 30 June 2023, who had post-ROSC oesophageal temperature measurements were included. OUTCOME MEASURE AND ANALYSIS: The primary outcome measure was survival to hospital discharge. Core temperature was defined as the first oesophageal temperature recorded following ROSC. Multivariable logistic regression evaluated the adjusted association between core temperature and survival to hospital discharge. MAIN RESULTS: Resuscitation was attempted in 3990 OHCA patients during the study period, of which 552 patients were included in the final analysis. The mean age was 61 years, and 402 (72.8%) patients were male. Among them, 194 (35.1%) survived to hospital discharge. The mean core temperature was lower in nonsurvivors compared with those who survived hospital discharge; 34.6 and 35.2 °C, respectively (mean difference, -0.66; 95% CI, -0.87 to -0.44; P < 0.001). The adjusted odds ratio for survival was 1.41 (95% CI, 1.09-1.83; P = 0.01) for every 1.0 °C increase in core temperature between 32.5 and 36.9 °C. CONCLUSION: In adult patients with ROSC following OHCA, early prehospital core temperature is independently associated with survival to hospital discharge.

Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK helicopter emergency medical service- a retrospective observational review of practice.

BACKGROUND: Accurate haemodynamic monitoring in the prehospital setting is essential. Non-invasive blood pressure measurement is susceptible to vibration and motion artefact, especially at extremes of hypotension and hypertension: invasive arterial blood pressure (IABP) monitoring is a potential solution. This study describes the largest series to date of cases of IABP monitoring being initiated prehospital. METHODS: This retrospective observational study was conducted at East Anglian Air Ambulance (EAAA), a UK helicopter emergency medical service (HEMS). It included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 and 20th April 2023. The following data were retrieved for all patients: sex; age; aetiology (medical cardiac arrest, other medical emergency, trauma); site of arterial cannulation; operator role (doctor/paramedic); time of insertion and, where applicable, times of pre-hospital emergency anaesthesia, and return of spontaneous circulation following cardiac arrest. Descriptive analyses were performed to characterise the sample. RESULTS: 13,556 patients were attended: IABP monitoring was initiated in 1083 (8.0%) cases, with a median age 59 years, of which 70.8% were male. 546 cases were of medical cardiac arrest: in 22.4% of these IABP monitoring was initiated during cardiopulmonary resuscitation. 322 were trauma cases, and the remaining 215 were medical emergencies. The patients were critically unwell: 981 required intubation, of which 789 underwent prehospital emergency anaesthesia; 609 received vasoactive medication. In 424 cases IABP monitoring was instituted en route to hospital. CONCLUSION: This study describes over 1000 cases of prehospital arterial catheterisation and IABP monitoring in a UK HEMS system and has demonstrated feasibility at scale. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting.

Agreement between arterial and end-tidal carbon dioxide in adult patients admitted with serious traumatic brain injury.

BACKGROUND: Low-normal levels of arterial carbon dioxide (PaCO2) are recommended in the acute phase of traumatic brain injury (TBI) to optimize oxygen and CO2 tension, and to maintain cerebral perfusion. End-tidal CO2 (ETCO2) may be used as a surrogate for PaCO2 when arterial sampling is less readily available. ETCO2 may not be an adequate proxy to guide ventilation and the effects on concomitant injury, time, and the impact of ventilatory strategies on the PaCO2-ETCO2 gradient are not well understood. The primary objective of this study was to describe the correlation and agreement between PaCO2 and ETCO2 in intubated adult trauma patients with TBI. METHODS: This study was a retrospective analysis of prospectively-collected data of intubated adult major trauma patients with serious TBI, admitted to the East of England regional major trauma centre; 2015-2019. Linear regression and Welch's test were performed on each cohort to assess correlation between paired PaCO2 and ETCO2 at 24-hour epochs for 120 hours after admission. Bland-Altman plots were constructed at 24-hour epochs to assess the PaCO2-ETCO2 agreement. RESULTS: 695 patients were included, with 3812 paired PaCO2 and ETCO2 data points. The median PaCO2-ETCO2 gradient on admission was 0.8 [0.4-1.4] kPa, Bland Altman Bias of 0.96, upper (+2.93) and lower (-1.00), and correlation R2 0.149. The gradient was significantly greater in patients with TBI plus concomitant injury, compared to those with isolated TBI (0.9 [0.4-1.5] kPa vs. 0.7 [0.3-1.1] kPa, p<0.05). Across all groups the gradient reduced over time. Patients who died within 30 days had a larger gradient on admission compared to those who survived; 1.2 [0.7-1.9] kPa and 0.7 [0.3-1.2] kPa, p<0.005. CONCLUSIONS: Amongst adult patients with TBI, the PaCO2-ETCO2 gradient was greater than previously reported values, particularly early in the patient journey, and when associated with concomitant chest injury. An increased PaCO2-ETCO2 gradient on admission was associated with increased mortality.

Critical hypertension in trauma patients following prehospital emergency anaesthesia: a multi-centre retrospective observational study.

BACKGROUND: Critical hypertension in major trauma patients is associated with increased mortality. Prehospital emergency anaesthesia (PHEA) is performed for 10% of the most seriously injured patients. Optimising oxygenation, ventilation, and cerebral perfusion, whilst avoiding extreme haemodynamic fluctuations are the cornerstones of reducing secondary brain injury. The aim of this study was to report the differential determinants of post-PHEA critical hypertension in a large regional dataset of trauma patients across three Helicopter Emergency Medical Service (HEMS) organisations. METHODS: A multi-centre retrospective observational study of consecutive adult trauma patients undergoing PHEA across three HEMS in the United Kingdom; 2015-2022. Critical hypertension was defined as a new systolic blood pressure (SBP) > 180mmHg within 10 min of induction of anaesthesia, or > 10% increase if the baseline SBP was > 180mmHg prior to induction. Purposeful logistical regression was used to explore variables associated with post-PHEA critical hypertension in a multivariable model. Data are reported as number (percentage), and odds ratio (OR) with 95% confidence interval (95%CI). RESULTS: 30,744 patients were attended by HEMS during the study period; 2161 received PHEA and 1355 patients were included in the final analysis. 161 (11.9%) patients had one or more new episode(s) of critical hypertension ≤ 10 min post-PHEA. Increasing age (compared with 16-34 years): 35-54 years (OR 1.76, 95%CI 1.03-3.06); 55-74 years (OR 2.00, 95%CI 1.19-3.44); ≥75 years (OR 2.38, 95%CI 1.31-4.35), pre-PHEA Glasgow Coma Scale (GCS) motor score four (OR 2.17, 95%CI 1.19-4.01) and five (OR 2.82, 95%CI 1.60-7.09), patients with a pre-PHEA SBP > 140mmHg (OR 6.72, 95%CI 4.38-10.54), and more than one intubation attempt (OR 1.75, 95%CI 1.01-2.96) were associated with post-PHEA critical hypertension. CONCLUSION: Delivery of PHEA to seriously injured trauma patients risks haemodynamic fluctuation. In adult trauma patients undergoing PHEA, 11.9% of patients experienced post-PHEA critical hypertension. Increasing age, pre-PHEA GCS motor score four and five, patients with a pre-PHEA SBP > 140mmHg, and more than intubation attempt were independently associated with post-PHEA critical hypertension.

The SWiFT trial (Study of Whole Blood in Frontline Trauma)-the clinical and cost effectiveness of pre-hospital whole blood versus standard care in patients with life-threatening traumatic haemorrhage: study protocol for a multi-centre randomised controlled trial.

BACKGROUND: Early blood transfusion improves survival in patients with life-threatening bleeding, but the optimal transfusion strategy in the pre-hospital setting has yet to be established. Although there is some evidence of benefit with the use of whole blood, there have been no randomised controlled trials exploring the clinical and cost effectiveness of pre-hospital administration of whole blood versus component therapy for trauma patients with life-threatening bleeding. The aim of this trial is to determine whether pre-hospital leukocyte-depleted whole blood transfusion is better than standard care (blood component transfusion) in reducing the proportion of participants who experience death or massive transfusion at 24 h. METHODS: This is a multi-centre, superiority, open-label, randomised controlled trial with internal pilot and within-trial cost-effectiveness analysis. Patients of any age will be eligible if they have suffered major traumatic haemorrhage and are attended by a participating air ambulance service. The primary outcome is the proportion of participants with traumatic haemorrhage who have died (all-cause mortality) or received massive transfusion in the first 24 h from randomisation. A number of secondary clinical, process, and safety endpoints will be collected and analysed. Cost (provision of whole blood, hospital, health, and wider care resource use) and outcome data will be synthesised to present incremental cost-effectiveness ratios for the trial primary outcome and cost per quality-adjusted life year at 90 days after injury. We plan to recruit 848 participants (a two-sided test with 85% power, 5% type I error, 1-1 allocation, and one interim analysis would require 602 participants-after allowing for 25% of participants in traumatic cardiac arrest and an additional 5% drop out, the sample size is 848). DISCUSSION: The SWiFT trial will recruit 848 participants across at least ten air ambulances services in the UK. It will investigate the clinical and cost-effectiveness of whole blood transfusion versus component therapy in the management of patients with life-threatening bleeding in the pre-hospital setting. TRIAL REGISTRATION: ISRCTN: 23657907; EudraCT: 2021-006876-18; IRAS Number: 300414; REC: 22/SC/0072, 21 Dec 2021.

Predictors of post-intubation hypotension in trauma patients following prehospital emergency anaesthesia: a multi-centre observational study.

BACKGROUND: Post-intubation hypotension (PIH) after prehospital emergency anaesthesia (PHEA) is prevalent and associated with increased mortality in trauma patients. The objective of this study was to compare the differential determinants of PIH in adult trauma patients undergoing PHEA. METHODS: This multi-centre retrospective observational study was performed across three Helicopter Emergency Medical Services (HEMS) in the UK. Consecutive sampling of trauma patients who underwent PHEA using a fentanyl, ketamine, rocuronium drug regime were included, 2015-2020. Hypotension was defined as a new systolic blood pressure (SBP) < 90 mmHg within 10 min of induction, or > 10% reduction if SBP was < 90 mmHg before induction. A purposeful selection logistic regression model was used to determine pre-PHEA variables associated with PIH. RESULTS: During the study period 21,848 patients were attended, and 1,583 trauma patients underwent PHEA. The final analysis included 998 patients. 218 (21.8%) patients had one or more episode(s) of hypotension ≤ 10 min of induction. Patients > 55 years old; pre-PHEA tachycardia; multi-system injuries; and intravenous crystalloid administration before arrival of the HEMS team were the variables significantly associated with PIH. Induction drug regimes in which fentanyl was omitted (0:1:1 and 0:0:1 (rocuronium-only)) were the determinants with the largest effect sizes associated with hypotension. CONCLUSION: The variables significantly associated with PIH only account for a small proportion of the observed outcome. Clinician gestalt and provider intuition is likely to be the strongest predictor of PIH, suggested by the choice of a reduced dose induction and/or the omission of fentanyl during the anaesthetic for patients perceived to be at highest risk.

Intubation success in prehospital emergency anaesthesia: a retrospective observational analysis of the Inter-Changeable Operator Model (ICOM).

BACKGROUND: Pre hospital emergency anaesthesia (PHEA) is a complex procedure with significant risks. First-pass intubation success (FPS) is recommended as a quality indicator in pre hospital advanced airway management. Previous data demonstrating significantly lower FPS by non-physicians does not distinguish between non-physicians operating in isolation or within physician teams. In several UK HEMS, the role of the intubating provider is interchangeable between the physician and critical care paramedic-termed the Inter-Changeable Operator Model (ICOM). The objectives of this study were to compare first-pass intubation success rate between physicians and critical care paramedics (CCP) in a large regional, multi-organisational dataset of trauma PHEA patients, and to report the application of the ICOM. METHODS: A retrospective observational study of consecutive trauma patients ≥ 16 years old who underwent PHEA at two different ICOM Helicopter Emergency Medical Services in the East of England, 2015-2020. Data are presented as number (percentage) and median [inter-quartile range]. Fisher's exact test was used to compare proportions, reported as odds ratio (OR (95% confidence interval, 95% CI)), p value. The study design complied with the STROBE (Strengthening The Reporting of Observational studies in Epidemiology) reporting guidelines. RESULTS: In the study period, 13,654 patients were attended. 674 (4.9%) trauma patients ≥ 16 years old who underwent PHEA were included in the final analysis: the median age was 44 [28-63] years old, and 502 (74.5%) were male. There was no significant difference in the FPS rate between physicians and CCPs-90.2% and 87.4% respectively, OR 1.3 (95% CI 0.7-2.5), p = 0.38. The cumulative first, second, third, and fourth-pass intubation success rates were 89.6%, 98.7%, 99.7%, and 100%. Patients who had a physician-operated initial intubation attempt weighed more and had a higher heart rate, compared to those who had a CCP-operated initial attempt. CONCLUSION: In an ICOM setting, we demonstrated 100% intubation success in adult trauma patients undergoing PHEA. There was no significant difference in first-pass intubation success between physicians and CCPs.

Prehospital determinants of successful resuscitation after traumatic and non-traumatic out-of-hospital cardiac arrest.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is prevalent in the UK. Reported survival is lower than in countries with comparable healthcare systems; a better understanding of outcome determinants may identify areas for improvement. METHODS: An analysis of 9109 OHCA attended in East of England between 1 January 2015 and 31 July 2017. Univariate descriptives and multivariable analysis were used to understand the determinants of survival for non-traumatic cardiac arrest (NTCA) and traumatic cardiac arrest (TCA). Two Utstein outcome variables were used: survival to hospital admission and hospital discharge. RESULTS: The incidence of OHCA was 55.1 per 100 000 population/year. The overall survival to hospital admission was 27.6% (95% CI 26.7% to 28.6%) and the overall survival to discharge was 7.9% (95% CI 7.3% to 8.5%). Survival to hospital admission and survival to hospital discharge were both greater in the NTCA group compared with the TCA group: 27.9% vs 19.3% p=0.001, and 8.0% vs 3.8% p=0.012 respectively.Determinants of NTCA and TCA survival were different, and varied according to the outcome examined. In NTCA, bystander cardiopulmonary resuscitation (CPR) was associated with survival at discharge but not at admission, and the likelihood of bystander CPR was dependent on geographical socioeconomic status. An air ambulance was associated with increased survival to both hospital admission and discharge in NTCA, but only with survival to admission in TCA. CONCLUSION: NTCA and TCA are clinically distinct entities with different predictors for outcome-future OHCA reports should aim to separate arrest aetiologies. Determinants of survival to hospital admission and discharge differ in a way that likely reflects the determinants of neurological injury. Bystander CPR public engagement may be best focused in more deprived areas.

The outcome of patients in traumatic cardiac arrest presenting to deployed military medical treatment facilities: data from the UK Joint Theatre Trauma Registry.

BACKGROUND: The UK military was continuously engaged in armed conflict in Iraq and Afghanistan between 2003 and 2014, resulting in 629 UK fatalities. Traumatic cardiac arrest (TCA) is a precursor to traumatic death, but data on military outcomes are limited. In order to better inform military treatment protocols, the aim of this study was to define the epidemiology of TCA in the military population with a particular focus on survival rates and injury patterns. METHODS: A retrospective database analysis of the UK Joint Theatre Trauma Registry was undertaken. Patients who were transported to a UK deployed hospital between 2003 and 2014 and suffered TCA were included. Those patients injured by asphyxiation, electrocution, burns without other significant trauma and drowning were excluded. Data included mechanism of injury, Injury Severity Score (ISS), Abbreviated Injury Scale (AIS) for each body region and survival to deployed (Role 3) field hospital discharge. RESULTS: 424 TCA patients were identified during the study period; median age was 23 years, with a median ISS of 45. The most common mechanism of injury was explosive (55.7%), followed by gunshot wound (38.9%), road traffic collision (3.5%), crush (1.7%) and fall (0.2%). 45 patients (10.6% (95% CI 8.0% to 13.9%)) survived to deployed (Role 3) hospital discharge. The most prevalent body region with a severe to maximum AIS injury was the head, followed by the lower limbs, thorax and abdomen. Haemorrhage secondary to abdominal and lower limb injury was associated with survival; traumatic brain injury was associated with death. CONCLUSIONS: This study has shown that short-term survival from TCA in a military population is 10.6%. With appropriate and aggressive early management, although unlikely, survival is still potentially possible in military patients who suffer traumatic cardiac arrest.

A comparison of Selective Aortic Arch Perfusion and Resuscitative Endovascular Balloon Occlusion of the Aorta for the management of hemorrhage-induced traumatic cardiac arrest: A translational model in large swine.

BACKGROUND: Survival rates remain low after hemorrhage-induced traumatic cardiac arrest (TCA). Noncompressible torso hemorrhage (NCTH) is a major cause of potentially survivable trauma death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) at the thoracic aorta (Zone 1) can limit subdiaphragmatic blood loss and allow for IV fluid resuscitation when intrinsic cardiac activity is still present. Selective Aortic Arch Perfusion (SAAP) combines thoracic aortic balloon hemorrhage control with intra-aortic oxygenated perfusion to achieve return of spontaneous circulation (ROSC) when cardiac arrest has occurred. METHODS AND FINDINGS: Male Yorkshire Landrace cross swine (80.0 ± 6.0 kg) underwent anesthesia, instrumentation for monitoring, and splenectomy. TCA was induced by laparoscopic liver lobe resection combined with arterial catheter blood withdrawal to achieve a sustained systolic blood pressure <10 mmHg, cardiac arrest. After 3 min of arrest, swine were allocated to one of three interventions: (1) REBOA plus 4 units of IV fresh whole blood (FWB), (2) SAAP with oxygenated lactated Ringer's (LR), 1,600 mL/2 min, or (3) SAAP with oxygenated FWB 1,600 mL/2 min. Primary endpoint was survival to the end of 60 min of resuscitation, a simulated prehospital phase. Thirty animals were allocated to 3 groups (10 per group)-5 protocol exclusions resulted in a total of 35 animals being used. Baseline measurements and time to cardiac arrest were not different amongst groups. ROSC was achieved in 0/10 (0%, 95% CI 0.00-30.9) REBOA, 6/10 (60%, 95% CI 26.2-87.8) SAAP-LR and 10/10 (100%, 95% CI 69.2-100.0) SAAP-FWB animals, p < 0.001. Survival to end of simulated 60-minute prehospital resuscitation was 0/10 (0%, 95% CI 0.00-30.9) for REBOA, 1/10 (10%, 95% CI 0.25-44.5) for SAAP-LR and 9/10 (90%, 95% CI 55.5-99.7) for SAAP-FWB, p < 0.001. Total FWB infusion volume was similar for REBOA (2,452 ± 0 mL) and SAAP-FWB (2,250 ± 594 mL). This study was undertaken in laboratory conditions, and as such may have practical limitations when applied clinically. Cardiac arrest in this study was defined by intra-aortic pressure monitoring that is not feasible in clinical practice, and as such limits the generalizability of findings. Clinical trials are needed to determine if the beneficial effects of SAAP-FWB observed in this laboratory study will translate into improved survival in clinical practice. CONCLUSIONS: SAAP conferred a superior short-term survival over REBOA in this large animal model of hemorrhage-induced traumatic cardiac arrest with NCTH. SAAP using an oxygen-carrying perfusate was more effective in this study than non-oxygen carrying solutions in TCA. SAAP can effect ROSC from hemorrhage-induced electrocardiographic asystole in large swine.

Factors affecting blood sample haemolysis: a cross-sectional study.

OBJECTIVE: To determine the effect of blood sampling through an intravenous catheter compared with a needle in Emergency Department blood sampling. METHODS: We undertook a prospective, cross-sectional study in a UK university teaching hospital Emergency Department. A convenience sample of 985 patients who required blood sampling via venepuncture was collected. A total of 844 complete sets of data were analysed. The median age was 63 years, and 57% of patients were male. The primary outcome measure was the incidence of haemolysis in blood samples obtained via a needle compared with samples obtained via an intravenous catheter. Secondary outcome measures defined the effect on sample haemolysis of the side of the patient the sample was obtained from, the anatomical location of sampling, the perceived difficulty in obtaining the sample, the order of sample tubes collected, estimated tourniquet time and bench time. Data were analysed with logistic regression, and expressed as odds ratios (95% confidence intervals; P-values). RESULTS: Blood samples obtained through an intravenous catheter were more likely to be haemolysed than those obtained via a needle, odds ratio 5.63 (95% confidence interval 2.49-12.73; P<0.001). CONCLUSION: Blood sampling via an intravenous catheter was significantly associated with an increase in the likelihood of sample haemolysis compared with sampling with a needle. Wherever practicable, blood samples should be obtained via a needle in preference to an intravenous catheter. Future research should include both an economic evaluation, and staff and patient satisfaction of separating blood sampling and intravenous catheter placement.

Prehospital and en route cricothyrotomy performed in the combat setting: a prospective, multicenter, observational study.

INTRODUCTION: Airway compromise is the third most common cause of potentially preventable combat death. Surgical cricothyrotomy is an infrequently performed but lifesaving airway intervention. There are limited published data on prehospital cricothyrotomy in civilian or military settings. Our aim was to prospectively describe the survival rate and complications associated with cricothyrotomy performed in the military prehospital and en route setting. METHODS: The Life-Saving Intervention (LSI) study is a prospective, institutional review board-approved, multicenter trial examining LSIs performed in the prehospital combat setting. We prospectively recorded LSIs performed on patients in theater who were transported to six combat hospitals. Trained site investigators evaluated patients on arrival and recorded demographics, vital signs, and LSIs performed. LSIs were predefined and include cricothyrotomies, chest tubes, intubations, tourniquets, and other procedures. From the large dataset, we analyzed patients who had a cricothyrotomy performed. Hospital outcomes were cross-referenced from the Department of Defense Trauma Registry. Descriptive statistics or Wilcoxon test (nonparametric) were used for data comparisons; statistical significance was set at p<.05. The primary outcome was success of prehospital and en route cricothyrotomy. RESULTS: Of the 1,927 patients enrolled, 34 patients had a cricothyrotomy performed (1.8%). Median age was 24 years (interquartile range [IQR]: 22.5-25 years), 97% were men. Mechanisms of injury were blast (79%), penetrating (18%), and blunt force (3%), and 83% had major head, face, or neck injuries. Median Glasgow Coma Scale score (GCS) was 3 (IQR: 3-7.5) and four patients had GCS higher than 8. Cricothyrotomy was successful in 82% of cases. Reasons for failure included left main stem intubation (n=1), subcutaneous passage (n=1), and unsuccessful attempt (n=4). Five patients had a prehospital basic airway intervention. Unsuccessful endotracheal intubation preceded 15% of cricothyrotomies. Of the 24 patients who had the provider type recorded, six had a cricothyrotomy by a combat medic (pre-evacuation), and 18 by an evacuation helicopter medic. Combat-hospital outcome data were available for 26 patients, 13 (50%) of whom survived to discharge. The cricothyrotomy patients had more LSIs than noncricothyrotomy patients (four versus two LSIs per patient; p<.0011). CONCLUSION: In our prospective, multicenter study evaluating cricothyrotomy in combat, procedural success was higher than previously reported. In addition, the majority of cricothyrotomies were performed by the evacuation helicopter medic rather than the prehospital combat medic. Prehospital military medics should receive training in decision making and be provided with adjuncts to facilitate this lifesaving procedure.