Performance of the Medical Priority Dispatch System® in Identifying Patients Requiring Chest Compressions at Overdose Prevention Services: A Retrospective Cohort Study

BACKGROUND AND AIMS

The Medical Priority Dispatch System (MPDS)® is used to triage 9-1-1 calls according to acuity, with certain coding receiving telecommunicator cardiopulmonary resuscitation (T-CPR) for suspected out-of-hospital cardiac arrest (OHCA). However, this may be challenging for those with drug poisoning emergencies, who may resemble OHCA. We sought to examine the performance of the system to correctly identify cases requiring T-CPR, specifically at overdose prevention services (OPS).

METHODS

This retrospective cohort study included patients attended by the provincial emergency medical system (EMS) (May 1, 2019-January 31, 2023). We calculated the diagnostic performance of MPDS® assessment of whether the case required T-CPR instructions against the gold standard of whether the patient was found pulseless on EMS clinician arrival. We compared performance among subgroups, specifically OPS vs other locations and drug poisoning-classified cases vs other case classifications.

RESULTS

Comparing OPS to other locations, the sensitivity of MPDS® was similar (66.7% vs 62.4%, p = 0.4), with lower specificity (87.3% vs 98.1%, p < 0.01) and positive predictive value (0.3% vs 35.7%, p < 0.01) and higher negative predictive value (99.9% vs 99.4%, p < 0.01). The negative likelihood ratio of MPDS® was 0.381 at OPS locations, compared with 0.383 at other locations, while the positive likelihood ratio was 5.24, compared with 32.36. In patients with drug poisoning emergencies, compared with other 9-1-1 events, MPDS® had higher sensitivity (83.6% vs 60.6%, p < 0.01) but lower specificity (77.6% vs 98.9%, p < 0.01) and positive predictive value (10.5% vs 48.5%, p < 0.01), and similar negative predictive value (99.33% vs 99.35%, p = 0.03). The negative likelihood ratio of MPDS® was 0.212 in drug poisoning emergencies compared with 0.398 for all other presentations, and the positive likelihood ratio was 3.73 compared with 57.88.

DISCUSSION AND CONCLUSIONS

The ability of MPDS® to correctly identify patients needing telecommunicator cardiopulmonary resuscitation instructions differed between OPS settings and other locations, frequently recommending T-CPR for patients not suffering OHCA at an OPS. Different strategies developed in collaboration with people who use substances are required to better tailor dispatch instructions prior to EMS arrival to avoid delays in life-saving interventions.

Informing Utstein-style reporting guidelines for prehospital thrombolysis: A scoping review

BACKGROUND

Rural Australians with acute myocardial infarction (AMI) face higher mortality rates due to limited access to specialised cardiac services. Paramedic-administered prehospital thrombolysis (PHT) has emerged as an alternative to primary percutaneous intervention (pPCI) for patients facing barriers or delays to cardiac care. There is variability in PHT practices among Australian ambulance services, lacking standardised definitions and outcome measures. The aim of this scoping review was to identify quality indicators and influencing factors associated with outcomes for patients receiving PHT.

METHODS

A systematic search of literature in SCOPUS and Academic Search Complete, CINAHL and Health Source: Nursing/Academic Edition databases via EBSCO (Health) was conducted following the Joanna Briggs Institute methodology. Peer-reviewed studies from the past decade were screened using search criteria relevant to prehospital thrombolysis and quality indicators. Data extraction was performed and themed using five domains from the Utstein-style template commonly known for standardised prehospital cardiac arrest reporting.

RESULTS

After removing duplicates, the search yielded 3596 articles with 28 empirical studies meeting inclusion criteria for the review. These were primarily retrospective cohort studies performed in Australia, Canada and the United States. The scoping review identified 24 clinical quality indicators and factors related to Emergency Medical Service (EMS) systems, AMI recognition and ambulance dispatch, patient variables, PHT processes and patient outcomes. These findings correlate to the Donabedian structure-process-outcome quality of care model and have utility to inform future PHT reporting guidelines for jurisdictional ambulance services.

CONCLUSIONS

Given the variability in prehospital practice across Australian ambulance services, standardised reporting on quality indicators for PHT is needed. The Utstein-style template used to report data on pre-hospital cardiac arrest, trauma and airway management could be used for quality improvement in PHT. This review presents 24 quality indicators representing system, recognition and response, patient, process, and outcomes related to PHT. These results could be used to inform a future Delphi study and Utstein-like reporting guideline for prehospital thrombolysis.

Impact of the COVID-19 pandemic on Canadian emergency medical system management of out-of-hospital cardiac arrest: A retrospective cohort study

AIM

We sought to describe the impact of the COVID-19 pandemic on the care provided by Canadian emergency medical system (EMS) clinicians to patients suffering out of hospital cardiac arrest (OHCA), and whether any observed changes persisted beyond the initial phase of the pandemic.

METHODS

We analysed cases of adult, non-traumatic, OHCA from the Canadian Resuscitation Outcome Consortium (CanROC) registry who were treated between January 27th, 2018, and December 31st, 2021. We used adjusted regression models and interrupted time series analysis to examine the impact of the COVID-19 pandemic (January 27th, 2020 - December 31st, 2021)on the care provided to patients with OHCA by EMS clinicians.

RESULTS

There were 12,947 cases of OHCA recorded in the CanROC registry in the pre-COVID-19 period and 17,488 during the COVID-19 period. We observed a reduction in the cumulative number of defibrillations provided by EMS (aRR 0.91, 95% CI 0.89 - 0.93, p < 0.01), a reduction in the odds of attempts at intubation (aOR 0.33, 95% CI 0.31 - 0.34, p < 0.01), higher rates of supraglottic airway use (aOR 1.23, 95% CI 1.16-1.30, p < 0.01), a reduction in vascular access (aOR for intravenous access 0.84, 95% CI 0.79 - 0.89, p < 0.01; aOR for intraosseous access 0.89, 95% CI 0.82 - 0.96, p < 0.01), a reduction in the odds of epinephrine administration (aOR 0.89, 95% CI 0.85 - 0.94, p < 0.01), and higher odds of resuscitation termination on scene (aOR 1.38, 95% CI 1.31 - 1.46, p < 0.01). Delays to initiation of chest compressions (2 min. vs. 3 min., p < 0.01), intubation (16 min. vs. 19 min., p = 0.01), and epinephrine administration (11 min. vs. 13 min., p < 0.01) were observed, whilst supraglottic airways were inserted earlier (11 min. vs. 10 min., p < 0.01).

CONCLUSION

The COVID-19 pandemic was associated with substantial changes in EMS management of OHCA. EMS leaders should consider these findings to optimise current OHCA management and prepare for future pandemics.

Paradoxical worsening of bradycardia following atropine administration

Introduction

Bradyarrhythmias are a common entity in both emergency and out-of-hospital (OOH) medicine. In unstable bradycardic patients, paramedics will often initiate life-saving therapies in the OOH setting. Clinical guidelines for bradyarrhythmias are largely consistent across the globe, with intravenous (IV) atropine recommended as a first-line therapy, escalating to IV adrenaline or isoprenaline and transcutaneous pacing where atropine is unsuccessful. In this case report, we describe a case in the OOH setting of ventricular standstill following the administration of atropine to a patient with bradycardia and 2:1 heart block.

Case presentation

The patient was a 77-year-old female presenting with a symptomatic 2:1 heart block. Following a single dose of 600 micrograms IV atropine, the patient deteriorated into ventricular standstill with a loss of consciousness and decorticate posturing. The patient was successfully managed with an IV infusion of adrenaline and subsequently received an implanted pacemaker in hospital.

Conclusion

The paradoxical worsening of this patient's bradycardia following atropine administration may have been related to the location of the heart block. It has been shown that patients with atrioventricular blocks at the level of the His-Purkinje fibres (infranodal) are at an increased risk of adverse events following atropine administration, while those at the nodal level or secondary to increased vagal tone are more likely to respond favourably. Paramedics should be prepared to manage unexpected adverse events secondary to atropine administration in patients with heart block.

PP41 British columbia emergency health services assess, see treat and refer palliative clinical pathway

Background/Research Objectives

Paramedic services have experienced a steadily increasing demand from palliative patients accessing 911 during times of acute crisis, and not wishing subsequent conveyance to ED. Early data indicates that many of these patients are NOT already connected to palliative care teams.

To address this demand and to connect patients to care, BCEHS introduced the Assess, See, Treat and Refer (ASTAR)-Palliative Clinical Pathway. Objectives are to reduce patient conveyance to ED, reduce hospitalizations and improve patient care through referral after non-conveyance.

Intervention

Paramedic activation of the ASTaR Palliative Clinical Pathway results in referral of non-conveyed palliative patients to local Home and Community Care teams and BCEHS paramedics. The referral occurs within 1-6 hours of paramedic contact and follow up occurs over the next 24-48 hours by telephone. This referral action provides safe, effective, patient-centred care for non-conveyed patients, and also fills a gap for connecting patients to local palliative care teams.

Impact

A retrospective case review of 183 cases was conducted. Symptom improvement was achieved in 70% of cases, the ED non-conveyance rate was 19%, and the time on task when palliative patients were treated at home and not conveyed was 37% less (52 minutes) than if palliative patients were transported (82 minutes). All 183 patients were connected to either the local home and community care team or BCEHS Rural Advanced Care Community Paramedics (RACCP).

Lessons Learned

Palliative patients frequently call 911 for help during acute crisis events and many of these patients do not wish conveyance to ED. The introduction of the ASTaR palliative clinical pathway provided safety netting and referral to appropriate care teams.

Chemical sedation of excited delirium in the pre-hospital setting

A 30-year-old male presents to emergency medical services profoundly combative with a Richmond Agitation‐Sedation Scale of +4 after reported use of intravenous methamphetamines. A preliminary diagnosis of excited delirium syndrome is made based on the history obtained and the decision is made to chemically sedate the patient. While preparing for sedation, you wonder which pharmacological agent will produce the fastest and safest sedation in this patient population.

A growth regulatory factor that can both inhibit and stimulate growth

A growth inhibitor that is produced by BSC-1 cells (African green monkey kidney epithelial cells) has been isolated from conditioned medium. It has been purified by gel chromatography and high performance liquid chromatography. It appears to be a protein with a relative molecular mass (Mr) of 24 000. It is extremely active as a growth inhibitor with some cells, but not with others. Approximately 50% inhibition of thymidine incorporation is observed with CCL64 cells at 0.05 ng/ml and with BSC-1 cells at 1 ng/ml. The growth inhibitor induces BSC-1 cells to synthesize and secrete a glycoprotein of approximately 48 000 Mr. It inhibits Na+ accumulation in BSC-1 cells. Recently, in collaboration with R. F. Tucker, G.D. Shipley and H. L. Moses (Mayo Foundation & Medical School), we have found that the growth inhibitor is very similar to and may be identical with transforming growth factor beta (TGF-beta). Our growth inhibitor stimulates colony formation in soft agar by AKR-2B cells, and it competes with TGF-beta in binding to cell surface receptors. TGF-beta, from human platelets, is extremely active as an inhibitor of thymidine incorporation by BSC-1 cells and CCL64 cells. The growth inhibitor/TGF-beta can, therefore, stimulate or inhibit growth, depending on the cells and the growth conditions.

Case report: massive postpartum transfusion of Jr(a+) red cells in the presence of anti-Jra

Jr(a) is a high-prevalence antigen. The rare Jr(a-) individuals can form anti-Jr(a) after exposure to the Jr(a) antigen through transfusion or pregnancy. The clinical significance of anti-Jr(a) is not well established. This study reports a case of a 31-year-old woman with a previously identified anti-Jr(a) who required massive transfusion of RBCs after developing life-threatening postpartum disseminated intravascular coagulopathy. Despite the emergent transfusion of 15 units of Jr(a) untested RBCs, she did not develop laboratory or clinical evidence of acute hemolysis. The patient's anti-Jr(a) had a pretransfusion titer of 4 and a monocyte monolayer assay (MMA) reactivity of 68.5% (reactivity > 5% is considered capable of shortening the survival of incompatible RBCs). The titer increased fourfold to 64 and the MMA reactivity was 72.5% on Day 10 posttransfusion. Review of laboratory data showed evidence of a mild delayed hemolytic transfusion reaction by Day 10 posttransfusion. Despite rare reports of hemolytic transfusion reactions due to anti-Jr(a) in the literature, most cases, including this one, report that this antibody is clinically insignificant or causes only mild delayed hemolysis. Clinicians should be advised to balance the risks of withholding transfusion with the small chance of significant hemolysis after transfusion of Jr(a+) RBCs in the presence of anti-Jr(a).

Current assessment of thromboembolic disease and pregnancy

This study was undertaken to assess incidence of deep venous thrombosis and pulmonary emboli in an inner-city pregnant population. Thromboembolic disease is believed to occur in 0.05 to 0.1 per cent of all pregnancies. Historically, postpartum thromboembolic disease was more common; decreased hospital stay may shift the thromboembolic disease to the antepartum period. A 5-year retrospective review of 4910 births assessed for incidence of thromboembolic disease, methods of diagnosis and treatment, and risk factors. A total of 4910 deliveries with 3978 transvaginal resulted in 30 episodes of deep venous thrombosis and five pulmonary emboli. All incidences of deep venous thrombosis but one were left-sided; four of five pulmonary emboli were postpartum. Of the epidsodes of deep venous thrombosis 17 per cent were first trimester, 50 per cent second trimester, 27 per cent third trimester, and 6 per cent postpartum. The diagnosis was confirmed by duplex scan in 24 of 30 patients. Heparin was the standard treatment. Deep venous thrombosis in pregnancy is most common in the second trimester; pulmonary emboli remain most common postpartum.

Amino acid sequence of the BSC-1 cell growth inhibitor (polyergin) deduced from the nucleotide sequence of the cDNA

The complete amino acid sequence of the BSC-1 cell growth inhibitor, including its precursor polypeptide, is reported. The sequence was deduced from the nucleotide sequence of the cDNA. The N-terminal amino acid sequence of the mature bioactive BSC-1 cell growth inhibitor is identical with the N-terminal sequences of the factors that have been called type beta 2 transforming growth factor and cartilage-inducing factor B, suggesting that these are identical. The complete amino acid sequence of the mature BSC-1 cell growth inhibitor differs from that of human type beta transforming growth factor in 32 of the 112 amino acids. Polyergin is proposed as the name for the BSC-1 cell growth inhibitor.

Activity of a kidney epithelial cell growth inhibitor on lung and mammary cells

A kidney epithelial cell growth inhibitor, isolated from BSC-1 cell-conditioned medium, has been found to be active on certain lung and mammary gland cell lines in culture. The most responsive cell observed thus far is the CCL64 mink lung cell line. With CCL64 cells, 60% inhibition of [3H]thymidine incorporation is observed at a 0.1 nanogram/ml concentration of the growth inhibitor, and approximately 95% inhibition at 1 nanogram/ml. A human mammary tumor cell line, Hs578T, shows 75% inhibition of [3H]thymidine incorporation, in cell culture. Preliminary studies indicate that injection of the kidney epithelial cell growth inhibitor in vivo into human mammary carcinomas growing in nude mice inhibits [3H]thymidine incorporation in the tumors.