Patient and Prehospital Predictors of Hospital Admission for Patients With and Without Histories of Diabetes Treated by Paramedics for Hypoglycemia: A Health Record Review Study.

OBJECTIVES: The objectives of this study were to describe the characteristics, management, and outcomes of patients treated by paramedics for hypoglycemia, and to determine the predictors of hospital admission for these patients within 72 hours of the initial hypoglycemia event. METHODS: We performed a health record review of paramedic call reports and emergency department records over a 12-month period. We queried prehospital databases to identify cases, which included all patients ⩾18 years with prehospital glucose readings of <72 mg/dl (<4.0 mmol/L) and excluded terminally ill and cardiac arrest patients. We developed and piloted a standardized data collection tool and obtained consensus on all data definitions before initiation of data extraction by trained investigators. Data analyses included descriptive statistics univariate and logistic regression presented as adjusted odds ratios (aOR) with 95% confidence intervals (95%CI). RESULTS: There were 791 patients with the following characteristics: mean age 56.2, male 52.3%, type 1 diabetes 11.6%, on insulin 43.3%, median initial glucose 54.0 mg/dl (3.0 mmol/L), from home 56.4%. They were treated by advanced care paramedics 80.1%, received intravenous D50 37.8%, intramuscular glucagon 17.8%, oral complex carbs/protein 25.7%, and accepted transport to hospital 70.2%. Among those transported, 134 (24.3%) were initially admitted and four more were admitted within 72 hours. One patient was admitted, discharged, and admitted again within 72 hours. Patients without documented histories of diabetes (aOR 2.35, CI 1.13-4.86), with cardiovascular disease (aOR 1.81, CI 1.10-3.00), on corticosteroids (aOR 4.63, CI 2.15-9.96), on oral hypoglycemic agent(s) (aOR 1.92, CI 1.02-3.62), or those given glucagon (aOR 1.77, CI 1.07-2.93) on scene were more likely to be admitted to hospital, whereas patients on insulin (aOR 0.49, CI 0.27-0.91), able to tolerate complex oral carbs/protein (aOR 0.22, CI 0.10-0.48), with final GCS scores of 15 (aOR 0.53, CI 0.34-0.83), or from public locations (aOR 0.40, CI 0.21-0.75) were less likely to be admitted. CONCLUSIONS: There are several patient and prehospital management characteristics which, in combination, could be incorporated into a safe clinical decision tool for patients who present with hypoglycemia.

Oxygen therapy in the pre-hospital setting for acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a global leading cause of morbidity and mortality, characterised by acute deterioration in symptoms. During these exacerbations, people are prone to developing alveolar hypoventilation, which may be partly caused by the administration of high inspired oxygen concentrations. OBJECTIVES: To determine the effect of different inspired oxygen concentrations ("high flow" compared to "controlled") in the pre-hospital setting (prior to casualty/emergency department) on outcomes for people with acute exacerbations of COPD (AECOPD). SEARCH METHODS: The Cochrane Airways Group Specialised Register, reference lists of articles and online clinical trial databases were searched. Authors of identified randomised controlled trials (RCTs) were also contacted for details of other relevant published and unpublished studies. The most recent search was conducted on 16 September 2019. SELECTION CRITERIA: We included RCTs comparing oxygen therapy at different concentrations or oxygen therapy versus placebo in the pre-hospital setting for treatment of AECOPD. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trial quality and extracted data. The primary outcome was all-cause and respiratory-related mortality. MAIN RESULTS: The search identified a total of 824 citations; one study was identified for inclusion and two studies are awaiting classification. The 214 participants involved in the included study were adults with AECOPD, receiving treatment by paramedics en route to hospital. The mean age of participants was 68 years. A reduction in pre/in-hospital mortality was observed in favour of the titrated oxygen group (two deaths in the titrated oxygen group compared to 11 deaths in the high-flow control arm; risk ratio (RR) 0.22, 95% confidence interval (CI) 0.05 to 0.97; 214 participants). This translates to an absolute effect of 94 per 1000 (high-flow oxygen) compared to 21 per 1000 (titrated oxygen), and a number needed to treat for an additional beneficial outcome (NNTB) of 14 (95% CI 12 to 355) with titrated oxygen therapy. Other than mortality, no other adverse events were reported in the included study. Wide confidence intervals were observed between groups for arterial blood gas (though this may be confounded by protocol infidelity in the included study for this outcome measure), treatment failure requiring invasive or non-invasive ventilation or hospital utilisation. No data were reported for quality of life, lung function or dyspnoea. Risk of bias within the included study was largely unclear, though there was high risk of bias in domains relating to performance and attrition bias. We judged the evidence to be of low certainty, according to GRADE criteria. AUTHORS' CONCLUSIONS: The one included study found a reduction in pre/in-hospital mortality for the titrated oxygen arm compared to the high-flow control arm. However, the paucity of evidence somewhat limits the reliability of these findings and generalisability to other settings. There is a need for robust, well-designed RCTs to further investigate the effect of oxygen therapies in the pre-hospital setting for people with AECOPD.

Barriers to Self-Reporting Patient Safety Incidents by Paramedics: A Mixed Methods Study.

BACKGROUND: A minimal amount of research exists examining the extent to which patient safety events occur within paramedicine and even fewer studies investigating patient safety systems for self-reporting by paramedics. The purpose of this study was to identify barriers to paramedic self-reporting of patient safety incidents (PSIs). METHODS: We randomly distributed paper-based surveys among 1,153 paramedics in an Ontario region in Canada. The survey described one of 5 different PSI clinical scenarios (near miss, adverse event, and minor, major or critical patient care variances) and listed 18 potential barriers to self-reporting PSIs as statements presented for rating on a 5-point Likert scale (very significant = 1 - very insignificant = 5). We invited comments on PSI self-reporting with 2 open-ended questions. We analyzed data with descriptive statistics, chi-square tests and Kruskal-Wallis H test. We used an inductive approach to qualitatively analyze emerging themes. RESULTS: We received responses from 1,133 paramedics (98.3%). Almost one third (28.4%) were Advanced Care Paramedics and 45.1% had >10 years' experience. The top 5 barriers to PSI self-reporting (very significant or significant, %) were the fear of being: punished (81.4%), suspended (79.6%), terminated (79.1%), investigated by Ministry of Health and Long-Term Care (78.4%), and decertified (78.0%). Overall, 64.1% responded they would self-report a given PSI. Intention to self-report a PSI varied according to scenario (22.8% near miss, 46.6% adverse event, 74.4% minor, 92.6% major, 95.6% critical). No association was found between level of training (p = 0.55) or years of experience (p = 0.10) and intention to self-report a PSI. Seven themes to improve PSI self-reporting by paramedics emerged from the qualitative data. CONCLUSIONS: A high proportion of fear-based barriers to self-reporting of PSIs exist among this study population. This suggests that a culture change is needed to facilitate the identification of future patient safety threats.

Evaluation of a prehospital endovascular therapy stroke bypass program.

INTRODUCTION: Prehospital stroke endovascular therapy bypass transports patients with suspected large vessel occlusion directly to an endovascular therapy capable center. Our objective was to determine if an endovascular therapy bypass protocol improved access to stroke treatments. Secondary objectives were to determine safety, effectiveness, and rate of subsequent interfacility transfers. METHODS: Endovascular therapy bypass in 2018 was implemented in Eastern Ontario, for patients with a Los-Angeles-Motor-Scale ≥ 4 (positive large vessel occlusion screen) with a 90-min transport time if < 6 h from last seen well. A before-after health record review was conducted from Dec 1, 2017 to Nov 30, 2019. A piloted data form was used to extract demographics, times, primary outcomes (endovascular therapy and intravenous (IV) tissue plasminogen activator (tPA) rate), and secondary outcomes (redirect to closer hospital, airway intervention, and subsequent interfacility transfer). We present descriptive statistics and odds ratios (OR) with 95% confidence intervals (CI) from multivariable logistic regression. RESULTS: We included 379 stroke patients (165 pre and 214 post-implementation). The endovascular therapy rate between groups was similar (14.1% vs 15.1%). The bypass had an OR of 0.98 (95% CI 0.54-1.78) for receiving endovascular therapy. IV tPA was given to 25.4% of patients pre vs 27.4% post-implementation (OR 1.06, 95% CI 0.65-1.74). No patients became unstable during transport, only one patient had an intubation attempt. The inappropriate bypass (false positive) rate was 12.7% pre vs 12.8% post-implementation (positive predictive value 87%). The bypass protocol had an OR of 1.06 (95% CI 0.58-1.95) for subsequent interfacility transfer with a mean of 2.7 h at the community site before transfer. CONCLUSIONS: Endovascular therapy stroke bypass with 90-min transport radius and Los-Angeles-Motor-Scale ≥ 4 was safe and well executed by paramedics. Our study did not show any difference in endovascular therapy rate from its implementation. The IV tPA rate was similar between groups despite potentially bypassing thrombolysis capable centers.

ABSTRAIT: INTRODUCTION: Le pontage de la thérapie endovasculaire pré-hospitalière transporte les patients présentant une occlusion suspectée de gros vaisseaux directement vers un centre capable de thérapie endovasculaire. Notre objectif était de déterminer si un protocole de pontage endovasculaire améliore l'accès aux traitements d'AVC. Les objectifs secondaires étaient de déterminer l'innocuité, l'efficacité et le taux des transferts d'interfacilité subséquents. MéTHODES: Le pontage par thérapie endovasculaire en 2018 a été mis en œuvre dans l'Est de l'Ontario, pour les patients ayant un test Los-Angeles-Motor-Scale 4 (test positif d'occlusion des gros vaisseaux) avec un temps de transport de 90 minutes si < 6 heures après la dernière observation. Un examen du dossier de santé avant-après a été effectué du 1er décembre 2017 au 30 novembre 2019. Un formulaire de données pilote a été utilisé pour extraire les données démographiques, les heures, les résultats primaires (traitement endovasculaire et taux d'activation du plasminogène par voie intraveineuse (IV) et les résultats secondaires (réorientation vers un hôpital plus proche, intervention sur les voies respiratoires et transfert d'interfacilité subséquent). Nous présentons des statistiques descriptives et des rapports de cotes (RC) avec des intervalles de confiance (IC) à 95 % à partir d'une régression logistique multivariée. RéSULTATS: Nous avons inclus 379 AVC (165 avant et 214 après la mise en œuvre). Le taux de traitement endovasculaire entre les groupes était similaire (14,1 % vs 15,1 %). Le pontage avait un RC de 0,98 (IC à 95 %, 0,54-1,78) pour le traitement endovasculaire. Le tPA IV a été administré à 25,4% des patients avant vs 27,4% après la mise en œuvre (OR 1,06, 95%CI 0,65-1,74). Aucun patient n'est devenu instable pendant le transport, seulement 1 patient a eu une tentative d'intubation. Le taux de pontage inapproprié (faux positif) était de 12,7 % avant et de 12,8 % après la mise en œuvre (valeur prédictive positive de 87 %). Le protocole de contournement avait un RC de 1,06 (IC à 95 % 0,58-1,95) pour le transfert d'interfacilité ultérieur avec une moyenne de 2,7 heures sur le site de la communauté avant le transfert. CONCLUSIONS: Le pontage d'AVC de thérapie endovasculaire avec un rayon de transport de 90 minutes et Los-Angeles-Motor-Scale 4 était sûr et bien exécuté par les ambulanciers. Notre étude n'a montré aucune différence dans le taux de thérapie endovasculaire par rapport à sa mise en œuvre. Le taux de tPA IV était similaire entre les groupes malgré le fait que les centres capables de contourner la thrombolyse étaient potentiellement contournés.

Variation in Survival After Out-of-Hospital Cardiac Arrest Between Emergency Medical Services Agencies.

Importance: Emergency medical services (EMS) deliver essential initial care for patients with out-of-hospital cardiac arrest (OHCA), but the extent to which patient outcomes vary between different EMS agencies is not fully understood. Objective: To quantify variation in patient outcomes after OHCA across EMS agencies. Design, Setting, and Participants: This observational cohort study was conducted in the Resuscitation Outcomes Consortium (ROC) Epistry, a prospective multicenter OHCA registry at 10 sites in North America. Any adult with OHCA treated by an EMS from April 2011 through June 2015 was included. Data analysis occurred from May 2017 to March 2018. Exposure: Treating EMS agency. Main Outcomes and Measures: The primary outcome was survival to hospital discharge. Secondary outcomes were return of spontaneous circulation at emergency department arrival and favorable functional outcome at hospital discharge (defined as a modified Rankin scale score ≤3). Multivariable hierarchical logistic regression models were used to adjust confounders and clustering of patients within EMS agencies, and calculated median odds ratios (MORs) were used to quantify the extent of residual variation in outcomes between EMS agencies. Results: We identified 43 656 patients with OHCA treated by 112 EMS agencies. At EMS agency level, we observed large variations in survival to hospital discharge (range, 0%-28.9%; unadjusted MOR, 1.43 [95% CI, 1.34-1.54]), return of spontaneous circulation on emergency department arrival (range, 9.0%-57.1%; unadjusted MOR, 1.53 [95% CI, 1.43-1.65]), and favorable functional outcome (range, 0%-20.4%; unadjusted MOR, 1.54 [95% CI, 1.40-1.73]). This variation persisted despite adjustment for patient-level and EMS agency-level factors known to be associated with outcomes (adjusted MOR for survival 1.56 [95% CI 1.44-1.73]; adjusted MOR for return of spontaneous circulation at emergency department arrival, 1.50 [95% CI, 1.41-1.62]; adjusted MOR for functionally favorable survival, 1.53 [95% CI, 1.37-1.78]). After restricting analysis to those who survived more than 60 minutes after hospital arrival and including hospital treatment characteristics, the variation persisted (adjusted MOR for survival, 1.49 [95% CI, 1.36-1.69]; adjusted MOR for functionally favorable survival, 1.34 [95% CI, 1.20-1.59]). Conclusions and Relevance: We found substantial variations in patient outcomes after OHCA between a large group of EMS agencies in North America that were not explained by documented patient-level and EMS agency-level variables.

A comparison of the universal TOR Guideline to the absence of prehospital ROSC and duration of resuscitation in predicting futility from out-of-hospital cardiac arrest.

INTRODUCTION: The Universal Termination of Resuscitation (TOR) Guideline accurately identifies potential out-of-hospital cardiac arrest (OHCA) survivors. However, implementation is inconsistent with some Emergency Medical Service (EMS) agencies using absence of return of spontaneous circulation (ROSC) as sole criterion for termination. OBJECTIVE: To compare the performance of the Universal TOR Guideline with the single criterion of no prehospital ROSC. Second, to determine factors associated with survival for patients transported without a ROSC. Lastly, to compare the impact of time to ROSC as a marker of futility to the Universal TOR Guideline. DESIGN: Retrospective, observational cohort study. PARTICIPANTS: Non-traumatic, adult (≥18 years) OHCA patients of presumed cardiac etiology treated by EMS providers. SETTING: ROC-PRIMED and ROC-Epistry post ROC-PRIMED databases between 2007 and 2011. OUTCOMES: Primary outcome was survival to hospital discharge and the secondary outcome was functional survival. We used multivariable regression to evaluate factors associated with survival in patients transported without a ROSC. RESULTS: 36,543 treated OHCAs occurred of which 9467 (26%) were transported to hospital without a ROSC. Patients transported without a ROSC who met the Universal TOR Guideline for transport had a survival of 3.0% (95% CI 2.5-3.4%) compared to 0.7% (95% CI 0.4-0.9%) in patients who met the Universal TOR Guideline for termination. The Universal TOR Guideline identified 99% of survivors requiring continued resuscitation and transportation to hospital including early identification of survivors who sustained a ROSC after extended durations of CPR. CONCLUSION: Using absence of ROSC as a sole predictor of futility misses potential survivors. The Universal TOR Guideline remains a strong predictor of survival.

Prehospital traumatic cardiac arrest: Management and outcomes from the resuscitation outcomes consortium epistry-trauma and PROPHET registries.

BACKGROUND: Traumatic arrests have historically had poor survival rates. Identifying salvageable patients and ideal management is challenging. We aimed to (1) describe the management and outcomes of prehospital traumatic arrests; (2) determine regional variation in survival; and (3) identify Advanced Life Support (ALS) procedures associated with survival. METHODS: This was a secondary analysis of cases from the Resuscitation Outcomes Consortium Epistry-Trauma and Prospective Observational Prehospital and Hospital Registry for Trauma (PROPHET) registries. Patients were included if they had a blunt or penetrating injury and received cardiopulmonary resuscitation. Logistic regression analyses were used to determine the association between ALS procedures and survival. RESULTS: We included 2,300 patients who were predominately young (Epistry mean [SD], 39 [20] years; PROPHET mean [SD], 40 [19] years), males (79%), injured by blunt trauma (Epistry, 68%; PROPHET, 67%), and treated by ALS paramedics (Epistry, 93%; PROPHET, 98%). A total of 145 patients (6.3%) survived to hospital discharge. More patients with blunt (Epistry, 8.3%; PROPHET, 6.5%) vs. penetrating injuries (Epistry, 4.6%; PROPHET, 2.7%) survived. Most survivors (81%) had vitals on emergency medical services arrival. Rates of survival varied significantly between the 12 study sites (p = 0.048) in the Epistry but not PROPHET (p = 0.14) registries.Patients in the PROPHET registry who received a supraglottic airway insertion or intubation experienced decreased odds of survival (adjusted OR, 0.27; 95% confidence interval, 0.08-0.93; and 0.37; 95% confidence interval, 0.17-0.78, respectively) compared to those receiving bag-mask ventilation. No other procedures were associated with survival. CONCLUSIONS: Survival from traumatic arrest may be higher than expected, particularly in blunt trauma and patients with vitals on emergency medical services arrival. Although limited by confounding and statistical power, no ALS procedures were associated with increased odds of survival. LEVEL OF EVIDENCE: Prognostic study, level IV.

Association of early withdrawal of life-sustaining therapy for perceived neurological prognosis with mortality after cardiac arrest.

BACKGROUND: Withdrawing life-sustaining therapy because of perceived poor neurological prognosis (WLST-N) is a common cause of hospital death after out-of-hospital cardiac arrest (OHCA). Although current guidelines recommend against WLST-N before 72h (WLST-N<72), this practice is common and may increase mortality. We sought to quantify these effects. METHODS: In a secondary analysis of a multicenter OHCA trial, we evaluated survival to hospital discharge and survival with favorable functional status (modified Rankin Score ≤3) in adults alive >1h after hospital admission. Propensity score modeling the probability of exposure to WLST-N<72 based on pre-exposure covariates was used to match unexposed subjects with those exposed to WLST-N<72. We determined the probability of survival and functionally favorable survival in the unexposed matched cohort, fit adjusted logistic regression models to predict outcomes in this group, and then used these models to predict outcomes in the exposed cohort. Combining these findings with current epidemiologic statistics we estimated mortality nationally that is associated with WLST-N<72. RESULTS: Of 16,875 OHCA subjects, 4265 (25%) met inclusion criteria. WLST-N<72 occurred in one-third of subjects who died in-hospital. Adjusted analyses predicted that exposed subjects would have 26% survival and 16% functionally favorable survival if WLST-N<72 did not occur. Extrapolated nationally, WLST-N<72 may be associated with mortality in approximately 2300 Americans each year of whom nearly 1500 (64%) might have had functional recovery. CONCLUSIONS: After OHCA, death following WLST-N<72 may be common and is potentially avoidable. Reducing WLST-N<72 has national public health implications and may afford an opportunity to decrease mortality after OHCA.

Comparison of amplification enzymes for Hepatitis C Virus quasispecies analysis.

BACKGROUND: Hepatitis C virus (HCV) circulates as quasispecies (QS), whose evolution is associated with pathogenesis. Previous studies have suggested that the use of thermostable polymerases without proofreading function may contribute to inaccurate assessment of HCV QS. In this report, we compared non-proofreading (Taq) with proofreading (Advantage High Fidelity-2; HF-2) polymerases in the sensitivity, robustness, and HCV QS diversity and complexity in the second envelope glycoprotein gene hypervariable region 1 (E2-HVR1) on baseline specimens from 20 patients in the HALT-C trial and in a small cohort of 12 HCV/HIV co-infected patients. QS diversity and complexity were quantified using heteroduplex mobility assays (HMA). RESULTS: The sensitivities of both enzymes were comparable at 50 IU/ml, although HF-2 was more robust and slightly more sensitive than Taq. Both enzymes generated QS diversity and complexity scores that were correlated (r = 0.68; p < 0.0001, and r = 0.47; p < 0.01; Spearman's rank correlation). QS diversity was similar for both Taq and HF-2 enzymes, although there was a trend for higher diversity in samples amplified by Taq (p = 0.126). Taq amplified samples yielded complexity scores that were significantly higher than HF-2 samples (p = 0.033). HALT-C patients who were HCV positive or negative following 20 weeks of pegylated IFN plus ribavirin therapy had similar QS diversity scores for Taq and HF-2 samples, and there was a trend for higher complexity scores from Taq as compared with HF-2 samples. Among patients with HCV and HIV co-infection, HAART increased HCV QS diversity and complexity as compared with patients not receiving therapy, suggesting that immune reconstitution drives HCV QS evolution. However, diversity and complexity scores were similar for both HF-2 and Taq amplified specimens. CONCLUSION: The data suggest that while Taq may overestimate HCV QS complexity, its use does not significantly affect results in cohort-based studies of HCV QS analyzed by HMA. However, the use of proofreading enzymes such as HF-2 is recommended for more accurate characterization of HCV QS in vivo.

Time on the scene and interventions are associated with improved survival in pediatric out-of-hospital cardiac arrest.

BACKGROUND: Survival is less than 10% for pediatric patients following out-of-hospital cardiac arrest. It is not known if more time on the scene of the cardiac arrest and advanced life support interventions by emergency services personnel are associated with improved survival. AIM: This study was performed to determine which times on the scene and which prehospital interventions were associated with improved survival. METHODS: We studied patients aged 3 days to 19 years old with out-of-hospital cardiac arrest, using the Resuscitation Outcomes Consortium cardiac arrest database from 11 North American regions, from 2005 to 2012. We evaluated survival to hospital discharge according to on-scene times (<10, 10 to 35 and >35 min). RESULTS: Data were available for 2244 patients (1017 infants, 594 children and 633 adolescents). Infants had the lowest rate of survival (3.7%) compared to children (9.8%) and adolescents (16.3%). Survival improved over the 7 year study period especially among adolescents. Survival was highest in the 10 to 35 min on-scene time group (10.2%) compared to the >35 min. group (6.9%) and the <10 min. group (5.3%, p=0.01). Intravenous or intra-osseous access attempts and fluid administration were associated with improved survival, whereas advanced airway attempts were not associated with survival and resuscitation drugs were associated with worse survival. CONCLUSIONS: In this observational study, a scene time of 10 to 35 min was associated with the highest survival, especially among adolescents. Access for fluid resuscitation was associated with increased survival but advanced airway and resuscitation drugs were not.

Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial.

OBJECTIVES: To compare standard high flow oxygen treatment with titrated oxygen treatment for patients with an acute exacerbation of chronic obstructive pulmonary disease in the prehospital setting. DESIGN: Cluster randomised controlled parallel group trial. SETTING: Ambulance service in Hobart, Tasmania, Australia. PARTICIPANTS: 405 patients with a presumed acute exacerbation of chronic obstructive pulmonary disease who were treated by paramedics, transported, and admitted to the Royal Hobart Hospital during the trial period; 214 had a diagnosis of chronic obstructive pulmonary disease confirmed by lung function tests in the previous five years. INTERVENTIONS: High flow oxygen treatment compared with titrated oxygen treatment in the prehospital (ambulance/paramedic) setting. MAIN OUTCOME MEASURE: Prehospital or in-hospital mortality. RESULTS: In an intention to treat analysis, the risk of death was significantly lower in the titrated oxygen arm compared with the high flow oxygen arm for all patients (high flow oxygen n=226; titrated oxygen n=179) and for the subgroup of patients with confirmed chronic obstructive pulmonary disease (high flow n=117; titrated n=97). Overall mortality was 9% (21 deaths) in the high flow oxygen arm compared with 4% (7 deaths) in the titrated oxygen arm; mortality in the subgroup with confirmed chronic obstructive pulmonary disease was 9% (11 deaths) in the high flow arm compared with 2% (2 deaths) in the titrated oxygen arm. Titrated oxygen treatment reduced mortality compared with high flow oxygen by 58% for all patients (relative risk 0.42, 95% confidence interval 0.20 to 0.89; P=0.02) and by 78% for the patients with confirmed chronic obstructive pulmonary disease (0.22, 0.05 to 0.91; P=0.04). Patients with chronic obstructive pulmonary disease who received titrated oxygen according to the protocol were significantly less likely to have respiratory acidosis (mean difference in pH 0.12 (SE 0.05); P=0.01; n=28) or hypercapnia (mean difference in arterial carbon dioxide pressure -33.6 (16.3) mm Hg; P=0.02; n=29) than were patients who received high flow oxygen. CONCLUSIONS: Titrated oxygen treatment significantly reduced mortality, hypercapnia, and respiratory acidosis compared with high flow oxygen in acute exacerbations of chronic obstructive pulmonary disease. These results provide strong evidence to recommend the routine use of titrated oxygen treatment in patients with breathlessness and a history or clinical likelihood of chronic obstructive pulmonary disease in the prehospital setting. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Register ACTRN12609000236291.