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BackgroundPrehospital neuroprotective strategies aim to prevent secondary insults (SIs) in traumatic brain injury (TBI). This includes haemodynamic optimisation in addition to oxygenation and ventilation targets achieved through rapid sequence intubation (RSI).The primary aim was to report the incidence and prevalence of SIs (prolonged hypotension, prolonged hypoxia and hyperventilation) and outcomes of patients with TBI who were intubated in the prehospital setting.MethodsA retrospective cohort study of adult patients with TBI who underwent RSI by a metropolitan road-based service in South-East Queensland, Australia between 1 January 2017 and 31 December 2020. Patients were divided into two cohorts based on the presence or absence of any SI sustained. Prolonged SIs were defined as occurring for ≥5 min. The association between SIs and mortality was examined in multivariable logistic regression and reported with adjusted ORs (aORs) and 95% CIs.Results277 patients were included for analysis. Median ‘Head’ Abbreviated Injury Scale and Injury Severity Score were 4 (IQR: 3–5) and 26 (IQR: 17–34), respectively. Most episodes of prolonged hypotension and prolonged hypoxia were detected with the first patient contact on scene. Overall, 28-day mortality was 26%. Patients who sustained any SI had a higher mortality than those sustaining no SI (34.9% vs 14.7%, pConclusionSIs were common in the early phase of prehospital care. The association of prolonged hypoxia and mortality in TBI is potentially more significant than previously recognised, and if corrected early, may improve outcomes. There may be a greater role for bystander intervention in prevention of early hypoxic insult in TBI.

Objective Rapidly and safely managing severe acute behavioural disturbance (ABD) in the prehospital setting is important for the welfare of both patient and prehospital clinician alike. We investigated the safety and effectiveness of ketamine as rescue sedation in patients with severe ABD. Methods This prospective observational study investigated ketamine use by a state ambulance service as rescue sedation for patients with severe ABD who remained agitated following droperidol administration. The primary outcome was the proportion of adverse events (vomiting, hypersalivation, emergence, over-sedation, airway obstruction, laryngospasm, hypoxia, bradypnoea and intubation). Secondary outcomes included time to sedation, requirement for additional sedation and rate of successful sedation. Results There were 105 presentations (males 69/102 [69%]; median age 31 years (16-83 years). The commonest causes of ABD were illicit drug (39%) and alcohol (33%) intoxication. The median total dose of intramuscular ketamine was 200 mg (interquartile range [IQR] 150-200 mg). There were 64 adverse events in 40 (38%) patients. Four had vomiting, two had hypersalivation, two had emergence, 15 were oversedated, four had hypoxia, three had bradypnoea and 16 were intubated. Sedation was achieved in 103 (98%) patients at a median time post-ketamine of 8 min (IQR 5-13 min). Additional sedation was administered to 41 patients (nine prehospital and 37 within 1 h of arriving to hospital). In 44 (42%) patients, ketamine successfully sedated the patient with no adverse effects and no ongoing sedation requirement. Conclusion The use of ketamine as rescue sedation in prehospital patients with severe ABD is effective. Adverse events are common but can be managed supportively.

Primary postpartum hemorrhage (PPH) is a life-threatening obstetric emergency that can be mitigated through the administration of a uterotonic to actively manage the third stage of labor. This study describes the prehospital administration of oxytocin by paramedics following attendance of out-of-hospital (OOH) births.A retrospective analysis was undertaken of all OOH births between the 1In total, 350 OOH births were included in this study with the majority involving multigravidas women (94.3%) and all but two involving singleton pregnancies. Oxytocin was administered following 222 births (63.4%), while 67 patients (19.1%) declined administration preferring a physiological third stage of labor, and in 61 cases (17.4%) oxytocin was withheld by the attending paramedic. There were no documented adverse events or side effects following administration. Oxytocin administration occurred on average 14 minutes (interquartile range 9-25) following the time of birth. The median time from oxytocin administration to placenta delivery was 10 minutes (interquartile range 5-22).Oxytocin is well accepted and safe treatment adjunct for the management of the third stage of labor in OOH births and should be considered for routine practice by other emergency medical services.

Large doses of intramuscular (IM) naloxone are commonly used in out-of-hospital settings to reverse opioid toxicity; however, they are used less commonly in hospitals because of concerns about opioid withdrawal, particularly agitation. We aimed to determine the frequency of severe agitation following a single 1.6 mg IM naloxone dose.We undertook a prospective study of adult (15 years) patients treated by an Australian state ambulance service with 1.6 mg IM administration of naloxone for respiratory depression (respiratory rate11 breaths/min and/or oxygen saturation93% in room air) caused by presumed opioid poisoning. The primary outcome was the proportion of presentations with severe agitation (Sedation Assessment Tool score1) within 1 hour of naloxone administration. Secondary outcomes were the proportion of presentations with acute opioid withdrawal (tachycardia [pulse rate100 beats/min], hypertension [systolic140 mm Hg], vomiting, agitation, seizure, myocardial infarction, arrhythmia, or pulmonary edema), and reversal of respiratory depression (respiratory rate10 breaths/min and saturation92% or Glasgow Coma Scale score 15).From October 2019 to July 2021, there were 197 presentations in 171 patients, with a median age of 41 years (range, 18 to 80 years); of the total patients, 119 were men (70%). The most common opioids were heroin (131 [66%]), oxycodone (14 [7%]), and morphine (11 [6%]). Severe agitation occurred in 14 (7% [95% confidence interval {CI} 4% to 12%]) presentations. Opioid withdrawal occurred in 76 presentations (39% [95% CI 32% to 46%]), most commonly in the form of tachycardia (18%), mild agitation/anxiety (18%) and hypertension (14%). Three presentations (1.5%) received chemical sedation for severe agitation within 1 hour of naloxone administration. A single 1.6 mg dose of naloxone reversed respiratory depression in 192 (97% [95% CI: 94% to 99%]) presentations.Severe agitation was uncommon following the administration of 1.6 mg IM naloxone and rarely required chemical sedation.

Objective: Acute behavioural disturbance in the elderly (≥65 years) is a significant issue for emergency medical services with increasing prevalence of dementia and aging populations. We investigated the pre-hospital safety and effectiveness of droperidol in the elderly with acute behavioural disturbance. Methods: This was a pre-hospital prospective observational 1-year study of elderly patients with acute behavioural disturbance. The primary outcome was proportion of adverse events (AEs) (airway intervention, oxygen saturation

One of the key ways in which quantum mechanics differs from relativity is that it requires a fixed background reference frame for spacetime. In fact, this appears to be one of the main conceptual obstacles to uniting the two theories. Additionally, a combination of the two theories is expected to yield non-classical, or "indefinite", causal structures. In this paper, we present a background-independent formulation of the process matrix formalism - a form of quantum mechanics that allows for indefinite causal structure - while retaining operationally well-defined measurement statistics. We do this by postulating an arbitrary probability distribution of measurement outcomes across discrete "chunks" of spacetime, which we think of as physical laboratories, and then requiring that this distribution be invariant under any permutation of laboratories. We find (a) that one still obtains nontrivial, indefinite causal structures with background independence, (b) that we lose the idea of local operations in distinct laboratories, but can recover it by encoding a reference frame into the physical states of our system, and (c) that permutation invariance imposes surprising symmetry constraints that, although formally similar to a superselection rule, cannot be interpreted as such., 8 pages + 3 page appendix

Introduction There are 10 government-regulated ambulance services (paramedic provider services) in Australasia who are members of the Council of Ambulance Authorities (CAA). These CAA-member services each produce clinical practice guidelines (CPGs), which guide the practice of their paramedics. Common to each set of CAA-member CPG is a guideline that addresses cardiac arrest due to ventricular fibrillation and pulseless ventricular tachycardia (pulseless VT/VF). This study sought to answer the question: ‘Are current CAA-member CPGs developed with sufficient methodological rigour to consistently produce guidelines that, according to validated, evidence-based best practices, can be recommended for clinical use?’ Methods This question was addressed by performing a comparison of existing CAA-member CPGs for pulseless VT/VF against the Appraisal of Guidelines for Research & Evaluation (AGREE II) instrument. All CPGs were anonymised and sent to each appraiser along with the AGREE II appraisal sheet. Appraisals were conducted independently for each CPG and returned to the lead author for collation. The anonymised results were then shared among all appraisers for consideration and discussion. Appraisers were free to change their appraisal after considering the comments from the other appraisers, and results were then converted into a final percent score for each CPG in accord with the recommended AGREE II instrument methodology. One appraisal question, in addition to the AGREE II criteria was added to each appraisal; the response to this was analysed separately. Results Nine CPGs were evaluated according to the AGREE II instrument. The appraisers gave passing marks to only two of the six domains in the AGREE II instrument: Domain 1 – Scope and Purpose (73%), and Domain 4 – Clarity of Presentation (74%). Less than passing marks were awarded for Domain 2 – Stakeholder Involvement (27%). Scores of less than 10% were awarded for Domain 5 – Applicability (8%) and Editorial Independence (1%). Conclusion Based on the findings of this paper, the authors conclude that it cannot be assumed that current CAA-member paramedic CPGs are developed with sufficient methodological rigour to consistently produce guidelines that, according to validated, evidence-based best practices can be recommended for clinical use. However, most of the authors agree that the CPGs reviewed could be recommended for clinical use with relatively minor modifications. It would be useful to determine whether end users of the CAA-member CPGs agree on the importance of characteristics of CPGs that the AGREE II instrument appraises.

Study objective: Although uncommon, children ( = 2 determined by the attending paramedic. The primary outcome was the proportion of adverse effects (need for airway intervention, oxygen saturation

Objectives To describe the characteristics and outcomes of cardiopulmonary resuscitation (CPR)-induced consciousness patients from a large database of out-of-hospital cardiac arrest (OHCA). Methods Included were adult patients, attended between January 2007 and December 2018 by the Queensland Ambulance Service, where resuscitation was attempted by paramedics. Manual review of records was undertaken to identify CPR-induced consciousness cases. Patients exhibiting purposeful limb/body movement during CPR, with or without displaying other signs, were considered to be CPR-induced consciousness. Characteristics and outcomes of CPR-induced consciousness patients were compared to those without CPR-induced consciousness. Results A total of 23 011 OHCA patients were included; of these, 52 (0.23%) were CPR-induced consciousness. This translates into an incidence rate of 2.3 cases per 1000 adult resuscitation attempts over 12 years. Combativeness/agitation was the most common sign of CPR-induced consciousness, described in 34.6% (18/52) of patients. CPR-induced consciousness patients had numerically higher rates of return of spontaneous circulation on hospital arrival (51.9% vs 28.6%), discharge survival (46.2% vs 15.1%) and 30-day survival (46.2% vs 14.7%), than those without CPR-induced consciousness; however, CPR-induced consciousness was not found to be an independent predictor of survival. Higher proportions of CPR-induced consciousness patients had arrest witnessed by paramedics, occurring in public places, of cardiac aetiology and initial shockable rhythm, than patients without CPR-induced consciousness. Conclusions CPR-induced consciousness in OHCA appears to be associated with higher survival rates. Standardised guidelines on recognition and management of CPR-induced consciousness remain to be established.

Background Appropriate fluid administration in severe burns is a cornerstone of early burns management. The American Burns Association’s (ABA) recommendation is to administer 2 mL–4 mL × burnt Body Surface Area (BSA) × weight in the first 24 h with half administered in the first eight hours. Unfortunately, the calculations involved are complex and clinicians do not estimate the BSA or weight well, which can lead to errors in the amount of fluid administered. To simplify cognitive load to calculate the fluid resuscitation of early burns, the investigators derived the PHIFTEEN B (15-B) guideline. The 15-B guideline estimates the initial hourly fluid for adults ≥ 50 kg to be: 15 mL × BSA (to the nearest 10%) • If >100 kg add 200 mL/h. Aims To model and determine the accuracy of the 15-B calculated based on the characteristics of a retrospective cohort of patients admitted with ≥ 20% BSA to the Royal Brisbane and Women’s Hospital (RBWH) Intensive Care Unit (ICU). Methods The 15-B formula was retrospectively calculated on the prehospital BSA estimate on patients admitted to the RBWH ICU. In addition, the 15-B guideline was modelled against a variety of weights and BSAs. The fluid volume was deemed to be clinically significant if it was greater than 250 mL/h outside the ABA’s recommendations. Results The ICU cohort consisted of 107 patients (63.2% male, median age 37 years), with a median ICU estimated BSA of 40% and a median ICU weight estimation of 80 kg. In 43.9% of the cohort, the magnitude of the proportional difference between prehospital and ICU BSA estimate was greater than 25%. The 15-B formula accurately estimated the hourly fluid for all BSA (20%–100%) and weight combinations (50 kg–140 kg) in a BSA- weight matrix. When prehospital BSA estimate was utilized, 15-B guideline accurately estimated the fluid to be given within clinically significant limits for 97.2% of cases. Conclusions The 15-B formula is a simple, easy to calculate guideline which approximates the early fluid estimates in severely burned patients despite inaccuracy in prehospital BSA estimates.

Objective: Naloxone is an established antidote for the treatment of heroin poisoning; however, dosing regimens vary widely, with a current trend towards small titrated intravenous dosing. This study aims to characterise naloxone use in the treatment of patients presenting with suspected heroin poisoning. Methods: This was a retrospective review of poisoned patients presenting to a clinical toxicology unit in Brisbane from January 2015 to December 2017. Patient demographics, clinical effects, naloxone dosing, observation periods and complications were extracted from the patient's medical records. Results: There were 117 presentations accounted for by 108 patients. Prehospital naloxone was provided to 57 (49%) patients, 46 of which received a standardised 1.6 mg i.m. dose. The remaining 60 (51%) patients received their first naloxone in hospital, with 58 (97%) receiving this by titrated i.v. doses. A subsequent naloxone infusion was required significantly more often in those treated with i.v. titrated naloxone compared to i.m. dose (27/69 [39%] vs 5/48 [10%], P = 0.0006). The need for parenteral sedation to manage acute behavioural disturbance following naloxone provision was rare (3/117 [3%]). Conclusions: In this retrospective observational study, a single large i.m. dose of naloxone reversed the toxicity of suspected heroin overdose in the majority of patients. In addition, patients were less likely to require repeated intermittent doses or naloxone infusion than those treated solely with i.v. naloxone. Further comparison in a prospective study is warranted to validate these observations in confirmed heroin overdose. Requirement for sedation secondary to acute behavioural disturbance was rare regardless of the route.

Acute behavioral disturbance is a common problem for emergency medical services. We aimed to investigate the safety and effectiveness of droperidol compared to midazolam in the prehospital setting.This was a prospective before and after study comparing droperidol to midazolam for prehospital acute behavioral disturbance, when the state ambulance service changed medications. The primary outcome was the proportion of adverse effects (airway intervention, oxygen saturation90%, respiratory rate12, systolic blood pressure90 mmHg, sedation assessment tool score -3 and dystonic reactions) in patients receiving sedation. Secondary outcomes included time to sedation, requirement for additional sedation, staff and patient injuries, and prehospital time.There were 141 patients administered midazolam and 149 patients administered droperidol in the study. Alcohol was the most common cause of acute behavioral disturbance. Fewer patient adverse events occurred with droperidol (11/149) compared to midazolam (33/141) (7% vs. 23%; absolute difference 16%; 95% confidence interval [CI]: 8% to 24%; p = 0.0001). Median time to sedation was 22 min (interquartile range [IQR]:18 to 35 min) for droperidol compared to 30 min (IQR:20 to 45 min) for midazolam. Additional prehospital sedation was required in 6/149 (4%) droperidol patients and 20/141 (14%) midazolam patients, and 11 (7%) droperidol and 59 (42%) midazolam patients required further sedation in the emergency department. There were no differences in patient or staff injuries, or prehospital time.The use of droperidol for acute behavioral disturbance in the prehospital setting is associated with fewer adverse events, a shorter time to sedation, and fewer requirements for additional sedation.

To describe the characteristics, clinical interventions and the outcomes of patients administered packed red blood cells (pRBCs) by a metropolitan, road based, doctor-paramedic trauma response team (TRT).A retrospective cohort study examining 18 months of historical data collated by the Queensland Ambulance Service TRT, the Pathology Queensland Central Transfusion Laboratory, the Royal Brisbane and Women's Hospital and the Princess Alexandra Hospital Trauma Services was undertaken.Over an 18-month period (1 January 2011 to 30 June 2012), 71 trauma patients were administered pRBCs by the TRT. Seven patients (9.9%) died on scene and 39 of the 64 patients (60.9%) transported to hospital survived to hospital discharge. 57 (89.1%) of the transported patients had an Injury Severity Score (ISS) 15, with a mean ISS, Revised Trauma Score (RTS) and Trauma-Injury Severity Score of 32.11, 4.70 and 0.57, respectively. No patients with an RTS 2 survived to hospital discharge. 53 patients (82.8%) received additional pRBCs in hospital with 17 patients (26.6%) requiring greater than 10 units pRBCs in the first 24 h. 47 patients (73.4%) required surgical or interventional radiological procedures in the first 24 h.There is a potential role for prehospital pRBC transfusions in an integrated civilian trauma system. The RTS calculated using the initial set of observations may be a useful tool in determining in which patients the administration of prehospital pRBC transfusions would be futile.

Objective To evaluate the feasibility, limitations and costs involved in providing prehospital trauma teams with packed red blood cells (pRBCs) for use in the prehospital setting. Methods A retrospective cohort study, examining 18 months of historical data collated by the Queensland Ambulance Service Trauma Response Team (TRT) and the Pathology Queensland Central Transfusion Laboratory was undertaken. Results Over an 18-month period (1 January 2011–30 June 2012), of 500 pRBC units provided to the TRT, 130 (26%) were administered to patients in the prehospital environment. Of the non-transfused units, 97.8% were returned to a hospital blood bank and were available for reissue. No instances of equipment failure directly contributed to wastage of pRBCs. The cost of providing pRBCs for prehospital use was $A551 (£361) for each unit transfused. Conclusions It is feasible and practical to provide prehospital trauma teams with pRBCs for use in the field. Use of pRBCs in the prehospital setting is associated with similar rates of pRBC wastage to that reported in emergency departments.