Medical Priority Dispatch System Protocol Research Articles

Dispatch Categories as Indicators of Out-of-Hospital Time Critical Interventions and Associated Emergency Department Outcomes

Objectives Emergency medical services (EMS) systems increasingly grapple with rising call volumes and workforce shortages, forcing systems to decide which responses may be delayed. Limited research has linked dispatch codes, on-scene findings, and emergency department (ED) outcomes. This study evaluated the association between dispatch categorizations and time-critical EMS responses defined by prehospital interventions and ED outcomes. Secondarily, we proposed a framework for identifying dispatch categorizations that are safe or unsafe to hold in queue. Methods This retrospective, multi-center analysis encompassed all 9-1-1 responses from 8 accredited EMS systems between 1/1/2021 and 06/30/2023, utilizing the Medical Priority Dispatch System (MPDS). Independent variables included MPDS Protocol numbers and Determinant levels. EMS treatments and ED diagnoses/dispositions were categorized as time-critical using a multi-round consensus survey. The primary outcome was the proportion of EMS responses categorized as time-critical. A non-parametric test for trend was used to assess the proportion of time-critical responses Determinant levels. Based on group consensus, Protocol/Determinant level combinations with at least 120 responses (∼1 per week) were further categorized as safe to hold in queue (<1% time-critical intervention by EMS and <5% time-critical ED outcome) or unsafe to hold in queue (>10% time-critical intervention by EMS or >10% time-critical ED outcome). Results Of 1,715,612 EMS incidents, 6% (109,250) involved a time-critical EMS intervention. Among EMS transports with linked outcome data (543,883), 12% had time-critical ED outcomes. The proportion of time-critical EMS interventions increased with Determinant level (OMEGA: 1%, ECHO: 38%, p-trend < 0.01) as did time-critical ED outcomes (OMEGA: 3%, ECHO: 31%, p-trend < 0.01). Of 162 unique Protocols/Determinants with at least 120 uses, 30 met criteria for safe to hold in queue, accounting for 8% (142,067) of incidents. Meanwhile, 72 Protocols/Determinants met criteria for unsafe to hold, accounting for 52% (883,683) of incidents. Seven of 32 ALPHA level Protocols and 3/17 OMEGA level Protocols met the proposed criteria for unsafe to hold in queue. Conclusions In general, Determinant levels aligned with time-critical responses; however, a notable minority of lower acuity Determinant level Protocols met criteria for unsafe to hold. This suggests a more nuanced approach to dispatch prioritization, considering both Protocol and Determinant level factors.

Emergency medical dispatchers’ experiences of using the Medical Priority Dispatch System telephone triage to identify maternity emergencies: a qualitative focus group study

ObjectivesThe ambulance service plays a pivotal role in the provision of care in out-of-hospital maternity emergencies. Telephone triage of this patient group is complex and must be sensitive to an...

Association between initial presenting level of consciousness and patient acuity – A potential application for secondary triage in emergency ambulance calls

IntroductionConscious state assessment is important for the triage of emergency patients. In this study, we measured the association between ambulance patients’ conscious state and high versus lower acuity, with a view to informing telephone triage assessment of conscious state. MethodsData were analysed from one year of emergency ambulance incidents in Perth, Western Australia. Patient conscious state at the time of paramedic arrival was compared to acuity (based on paramedic assessment and management). We determined the proportion of high-acuity patients across six levels of consciousness (Alert, Confused, Drowsy, Voice Response, Pain Response, Unresponsive) overall, and within individual protocols of the Medical Priority Dispatch System (MPDS). ResultsThe proportion of high acuity patients increased with each step across the consciousness scale. Applying conscious state as a binary predictor of acuity, the largest increases occurred moving the threshold from Alert to Confused (22.0–48.6% high acuity) and Drowsy to Voice Response (61.9–89.5% high acuity). The Area Under the Curve (AUC) of the Receiver Operating Characteristic was 0.65. Within individual protocols, the highest AUC was in Cardiac Arrest (0.89), Overdose/Poisoning (0.81), Unknown Problem (0.76), Diabetic Problem, (0.74) and Convulsions/Fitting (0.73); and lowest in Heart problems (0.55), Abdominal Pain (0.55), Breathing Problems (0.55), Back Pain (0.53), and Chest Pain (0.52). ConclusionBased on these proportions of high acuity patients, it is reasonable to consider patients with any altered conscious state a high priority. The value of conscious state assessment for predicting acuity varies markedly between MPDS protocols. These findings could help inform secondary triage of ambulance patients during the emergency call.

Epidemiology of emergency ambulance service calls related to COVID-19 in Scotland: a national record linkage study

BackgroundCOVID-19 has overwhelmed health services across the world; its global death toll has exceeded 5.3 million and continues to grow. There have been almost 15 million cases of COVID-19 in the UK. The need for rapid accurate identification, appropriate clinical care and decision making, remains a priority for UK ambulance service. To support identification and conveyance decisions of patients presenting with COVID-19 symptoms the Scottish Ambulance Service introduced the revised Medical Priority Dispatch System Protocol 36, enhanced physician led decision support and prehospital clinical guidelines. This study aimed to characterise the impact of these changes on the pathways and outcomes of people attended by the SAS) with potential COVID-19.MethodsA retrospective record linkage cohort study using National Data collected from NHS Scotland over a 5 month period (April–August 2020).ResultsThe SAS responded to 214,082 emergency calls during the study time period. The positive predictive value of the Protocol 36 to identify potentially COVID-19 positive patients was low (17%). Approximately 60% of those identified by Protocol 36 as potentially COVID-19 positive were conveyed. The relationship between conveyance and mortality differed between Protocol 36 Covid-19 positive calls and those that were not. In those identified by Protocol 36 as Covid-19 negative, 30 day mortality was higher in those not conveyed (not conveyed 9.2%; conveyed 6.6%) but in the Protocol 36 Covid-19 positive calls, mortality was higher in those conveyed (not conveyed 4.3% conveyed 8.8%). Thirty-day mortality rates of those with COVID-19 diagnosed through virology was between 28.8 and 30.2%.ConclusionThe low positive predictive value (17%) of Protocol 36 in identifying potential COVID-19 in patients emphasises the importance of ambulance clinicians approaching each call as involving COVID-19, reinforcing the importance of adhering to existing policy and continued use of PPE at all calls. The non-conveyance rate of people that were categorised as COVID-19 negative was higher than in the preceding year in the same service. The reasons for the higher rates of non-conveyance and the relationship between non conveyance rates and death at 3 and 30 days post index call are unknown and would benefit from further study.

Using a category to accomplish resistance in the context of an emergency call

We report a single case analysis of a recorded emergency call with particular reference to the use of the non-recognitional categorical person reference ‘a personal doctor’ in the sequential context created by the Medical Priority Dispatch System (MPDS) protocol routinely used by the emergency services. We describe both the position and the composition of the turn in which this categorical person reference is deployed in order to analyse the action accomplished by its selection. We show how this category reference is selected to support the action in which the speaker is otherwise engaged, which is to resist the sequential trajectory proposed by his interlocutor (giving instructions for cardiopulmonary resuscitation). Our analysis makes two key contributions: 1) it provides a concrete detailed exemplar of how analysts can ground claims about category-bound inferences in the empirical practices of talk in interaction and 2) it extends existing work on emergency calls by relating their sequential structure to the MPDS protocol.

Analysis of Emergency Medical Services Triage and Dispatch Errors by Registered Nurses in Italy

IntroductionThe major elements of an effective emergency medical services (EMS) system include a single telephone access number, accurate assessment of the urgency of the health problem, and timely dispatch of appropriate personnel and equipment. In Italy, EMS calls are managed by emergency operations centers by registered nurses who have received specialized education in this function. The nurses determine the criticality of the situations and assign an EMS response priority level identified by a color code, ranging from red (very critical) to green (not critical). At times, the severity of a situation may be underestimated, resulting in assignment of a lower EMS response priority and the potential for patient death (code black). The purpose of this study was to analyze factors associated with registered nurse under-triage of EMS calls subsequently found to be associated with deaths, termed “green-black code” cases. MethodsWe carried out a retrospective qualitative analysis of EMS telephone conversations using Fele’s conversation analysis method. The characteristics of green-black code calls were compared with the characteristics of the population of all EMS calls during the study period. ResultsThe study patients were older, with a mean age of 81.6 years. The callers were individuals calling on behalf of the patients, rather than the patients themselves. The callers reported symptoms that were not life-threatening. Nurse operators did not always inquire about the patients’ vital signs as required by the Medical Priority Dispatch System protocol. The phone conversations were shorter than normal (54.26 seconds vs 65 seconds). DiscussionAlthough the importance of dispatch system protocols is wellknown, it is also important that nurse triage operators have proper training to ensure that major parameters such as vital signs and symptomatology are obtained and to reduce caller stress level.

Dispatchers impression plus Medical Priority Dispatch System reduced dispatch centre times in cases of out of hospital cardiac arrest. Pre-alert – A prospective, cluster randomized trial

Aim of the studyDispatch centre processing times for out-of-hospital cardiac arrest or critically ill patients should be as short as possible. A modified ‘pre-alert’ dispatch workflow might be able to improve the processing time. MethodsBetween October 2010 and May 2011 dispatch events, suspicious for cardiac arrest, were prospectively randomized in 24h clusters. The emergency medical service of the intervention group got, based on the dispatchers impression, a ‘pre-alert’ alarm-message followed by the standard Medical Priority Dispatch System query whereas the control group did not. ResultsIn 225 clusters 1500 events were eligible for analysis. Data are presented as median and 25–75 interquartile ranges. Per-protocol analysis demonstrated for the intervention group on ‘pre-alert’ days a median processing time of 143s (109–187; n=256) versus 198s (167–255; n=502) in the control group on non ‘pre-alert’ days, with a difference of 0.23 log-seconds (p<0.001; 95% CI 0.74–0.28). In critical ill patients, intention-to-treat analysis showed for the intervention group a median of 168s (131–264; n=153) versus 239s (176–309; n=164) in the control group, with a difference of 1.4 log-seconds (p<0.001; 95% CI 1.25–1.55). ConclusionDispatch times can effectively be reduced in cases of out-of-hospital cardiac arrest or critical ill patients with a ‘pre-alert’ dispatch workflow in combination with the Medical Priority Dispatch System protocol. This might play an important role in improving patient care.

Medical Priority Dispatch System Breathing Problems Protocol Key Question Combinations are Associated with Patient Acuity

The Breathing Problems Chief Complaint (CC) protocol in the Medical Priority Dispatch System (MPDS) was the system's most frequently used protocol. While "severe breathing problems" is a significant predictor of cardiac arrest (CA), previous data have demonstrated that the DELTA-level determinant codes in this CC contain patients across a wide spectrum of acuity. The hypothesis in this study was that certain combinations of caller answers to the breathing problems protocol key questions (KQs) are correlated with different but specific patient acuities. This was a retrospective study conducted at one International Academies of Emergency Dispatch (IAED) Accredited Center of Excellence. Key Question combinations were generated and analyzed from 11 months of dispatch data, and extracted from MPDS software and the computer assisted dispatch system. Descriptive statistics were used to evaluate measures between study groups. Forty-two thousand cases were recorded; 52% of patients were female and the median age was 61 years. Overall, based on the original MPDS Protocol (before generating KQ combinations), patients with abnormal breathing and clammy conditions were the youngest. The MPDS DELTA-level constituted the highest percentage of cases (74.0%) and the difficulty speaking between breaths (DSBB) condition was the most prevalent (50.3%). Ineffective breathing and not alert conditions had the highest cardiac arrest quotient (CAQ). Based on the KQ combinations, the CA patients who also had the not alert condition were significantly older than other patients. The percentage of CA outcomes in asthmatic patients was significantly higher in DSBB plus not alert; DSBB plus not alert plus changing color; and DSBB plus not alert plus clammy conditions cases, compared to asthmatic abnormal breathing cases. The study findings demonstrated that MPDS KQ answer combinations relate to patient acuity. Cardiac arrest patients are significantly less likely to be asthmatic than those without CA, and vice versa. Using a prioritization scheme that accounts for the presence of either single or multiple signs and/or symptom combinations for the Breathing Problems CC protocol would be a more accurate method of assigning DELTA-level cases in the MPDS.

The Accuracy of Emergency Medical Dispatcher-Assisted Layperson-Caller Pulse Check Using the Medical Priority Dispatch System Protocol

Knowing the pulse rate of a patient in a medical emergency can help to determine patient acuity and the level of medical care required. Little evidence exists regarding the ability of a 911 layperson-caller to accurately determine a conscious patient's pulse rate. Hypothesis The hypothesis of this study was that, when instructed by a trained emergency medical dispatcher (EMD) using the scripted Medical Priority Dispatch System (MPDS) protocol Pulse Check Diagnostic Tool (PCDxT), a layperson-caller can detect a carotid pulse and accurately determine the pulse rate in a conscious person. This non-randomized and non-controlled prospective study was conducted at three different public locations in the state of Utah (USA). A healthy, mock patient's pulse rate was obtained using an electrocardiogram (ECG) monitor. Layperson-callers, in turn, initiated a simulated 911 phone call to an EMD call-taker who provided instructions for determining the pulse rate of the patient. Layperson accuracy was assessed using correlations between the layperson-caller's finding and the ECG reading. Two hundred sixty-eight layperson-callers participated; 248 (92.5%) found the pulse of the mock patient. There was a high correlation between pulse rates obtained using the ECG monitor and those found by the layperson-callers, overall (94.6%, P < .001), and by site, gender, and age. Layperson-callers, when provided with expert, scripted instructions by a trained 911 dispatcher over the phone, can accurately determine the pulse rate of a conscious and healthy person. Improvements to the 911 instructions may further increase layperson accuracy.

Utilization of Prehospital Dispatch Protocols to Identify Low-Acuity Patients

Objectives. To describe the experience of a U.S. emergency medical services (EMS) agency utilizing a dispatch algorithm to identify low-acuity patients and determine whether secondary telephone triage by a nurse was associated with subsequent hospital admission among those patients. Methods. This was a retrospective study of all patients meeting the low-acuity Omega classification by the Medical Priority Dispatch System (MPDS) in a large urban EMS system, conducted in two phases. Patients were excluded from the study if a refusal for transport was obtained, the call was received from a third-party caller, the MPDS system was not used, the patient was being referred from a skilled nursing facility, school, or university nursing office or physician's office, or if the call was referred to the Carolina Poison Center. Patients were enrolled over two phases using two different versions of the MPDS protocol, and in phase 2 patients were offered the option of speaking with an advice-line nurse. The outcome of interest was emergency department disposition, classified as hospital admission or discharge home. Admission to an intensive care unit (ICU) bed was also collected as a subcategory of hospital admission. Results. Of the 1,862 patients in phase 1, 69.3% were discharged home from the emergency department, whereas in phase 2, 73.0% of the 1,078 patients were discharged home. Individuals were most frequently admitted to the hospital across both phases if they had a dispatch determinant of pregnancy, psychiatric/behavioral, fall, sick person. Hospital admission was also associated with receiving an EMS or emergency department procedure. There were 530 patients in phase 2 who underwent secondary triage by an advice-line nurse. Among this cohort of patients, 134 (25.3%) required subsequent hospital admission, with a further three (2.2%) requiring an ICU admission. Conclusions. This study identified a method for classifying patients during the dispatch period as low-acuity while attempting to ensure that those individuals received the medical care that they needed. Key words: emergency medical services; emergency medical dispatch; triage.

Time to First Compression Using Medical Priority Dispatch System Compression-First Dispatcher-Assisted Cardiopulmonary Resuscitation Protocols

Introduction. Without bystander cardiopulmonary resuscitation (CPR), cardiac arrest survival decreases 7%–10% for every minute of delay until defibrillation. Dispatcher-assisted CPR (D-CPR) has been shown to increase the rates of bystander CPR and cardiac arrest survival. Other reports suggest that the most critical component of bystander CPR is chest compressions with minimal interruption. Beginning with version 11.2 of the Medical Priority Dispatch System (MPDS) protocols, instructions for mouth-to-mouth ventilation (MTMV) and pulse check were removed and a compression-first pathway was introduced to facilitate rapid delivery of compressions. Additionally, unconscious choking and third-trimester pregnancy decision-making criteria were added in versions 11.3 and 12.0, respectively. However, the effects of these changes on time to first compression (TTFC) have not been evaluated. Objective. We sought to quantify the TTFC of MPDS versions 11.2, 11.3, and 12.0 for all calls identified as cardiac arrest on call intake that did not require MTMV instruction. Methods. Audio recordings of all D-CPR events for October 2005 through May 2010 were analyzed for TTFC. Differences in TTFC across versions were compared using the Kruskal-Wallis test. Results. A total of 778 cases received D-CPR. Of these, 259 were excluded because they met criteria for MTMV (pediatric patients, allergic reaction, etc.), were missing data, or were not initially identified as cardiac arrest. Of the remaining 519 calls, the mean TTFC was 240 seconds, with no significant variation across the MPDS versions (p = 0.08). Conclusions. Following the removal of instructions for pulse check and MTMV, as well as other minor changes in the MPDS protocols, we found the overall TTFC to be 240 seconds with little variation across the three versions evaluated. This represents an improvement in TTFC compared with reports of an earlier version of MPDS that included pulse checks and MTMV instructions (315 seconds). However, the MPDS TTFC does not compare favorably with reports of older, non-MPDS protocols that included pulse checks and MTMV. Efforts should continue to focus on improving this key, and modifiable, determinant of cardiac arrest survival. Key words: emergency medical dispatch; emergency medical services; prehospital; paramedic; cardiac arrest; CPR

Comparative Evaluation of Stroke Triage Algorithms for Emergency Medical Dispatchers (MeDS): Prospective Cohort Study Protocol

BackgroundStroke is a major cause of death and leading cause of disability in the United States. To maximize a stroke patient's chances of receiving thrombolytic treatment for acute ischemic stroke, it is important to improve prehospital recognition of stroke. However, it is known from published reports that emergency medical dispatchers (EMDs) using Card 28 of the Medical Priority Dispatch System protocols recognize stroke poorly. Therefore, to improve EMD's recognition of stroke, the National Association of Emergency Medical Dispatchers recently designed a new diagnostic stroke tool (Cincinnati Stroke Scale -CSS) to be used with Card 28. The objective of this study is to determine whether the addition of CSS improves diagnostic accuracy of stroke triage.Methods/DesignThis prospective experimental study will be conducted during a one-year period in the 911 call center of Santa Clara County, CA. We will include callers aged ≥ 18 years with a chief complaint suggestive of stroke and second party callers (by-stander or family who are in close proximity to the patient and can administer the tool) ≥ 18 years of age. Life threatening calls will be excluded from the study. Card 28 questions will be administered to subjects who meet study criteria. After completion of Card 28, CSS tool will be administered to all calls. EMDs will record their initial assessment of a cerebro-vascular accident (stroke) after completion of Card 28 and their final assessment after completion of CSS. These assessments will be compared with the hospital discharge diagnosis (ICD-9 codes) recorded in the Office of Statewide Health Planning and Development (OSHPD) database after linking the EMD database and OSHPD database using probabilistic linkage. The primary analysis will compare the sensitivity of the two stroke protocols using logistic regression and generalizing estimating equations to account for clustering by EMDs. To detect a 15% difference in sensitivity between the two groups with 80% power, we will enroll a total of 370 subjects in this trial.DiscussionA three week pilot study was performed which demonstrated the feasibility of implementation of the study protocol.

Predictive Ability of Emergency Medical Priority Dispatch System Protocols Should Be Assessed at the Atomic Level of the Determinant Code

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Compliance With and Use of Up-to-Date National Academies of Medical Dispatch Medical Priority Dispatch System Protocols in Dispatch Practice and Research Studies Must Be a Requirement

To the Editor: We observed significant omissions and errors in the study’s methods/design, findings, and conclusions in the recent paper by Buck et al,1 which we respectfully want to point out. First, the National Academies of Emergency Dispatch Medical Priority Dispatch System (MPDS) protocol version (Version 11.1, valid from 2001 to 2004) used in this study1 is significantly outdated. Three subsequent versions (Version 11.2, valid from 2004 to 2006; Version 11.3, valid from 2006 to 2008; and Version 12.0, valid from 2008 to date) have been issued, each containing significant clinically predictive modifications in the stroke protocol (Protocol 28). Using an outdated protocol is unsafe in a communication center, not the standard of dispatch practice, and misleads readers about the “current” effectiveness of the state of the art of an evolving protocol system. In the MPDS Version 11.1 protocol’s rules at that time, a …

Profile of Emergency Medical Dispatch Calls for Breathing Problems within the Medical Priority Dispatch System Protocol

A common chief complaint to emergency dispatch communication centers worldwide is "breathing problems". The chief complaint of breathing problems represents a wide spectrum of underlying diseases, patient conditions, and onset types. The current debate is on the potential ability of a dispatch protocol to safely and with high specificity, differentiate patients with minor or non-critical conditions from those conditions that pose risk to the patient and require advanced life support evaluation and care. This issue also has extended into the paramedic prehospital evaluation realm. The objective of this study was to describe the distribution of Medical Priority Dispatch System (MPDS) codes representing the spectrum of clinical descriptions within the breathing problems chief complaint and their associated outcomes, at the scene and during transport, as determined by [UK] paramedics. A retrospective, one-year study (September 2005 to August 2006) of a de-identified aggregate dataset from the London Ambulance Service (LAS) Trust was evaluated. A profile of the distribution of calls, incidents, patients, and outcomes (cardiac arrest [CA] and blue-in [BI] high acuity i.e., patients transported with lights and siren based on paramedic protocol) for the breathing problems chief complaint was evaluated. Odds ratios and 95% confidence intervals (CI) were used to quantify associations between the MPDS priority level's concurrent asthmatic conditions and outcomes. Two-sided Fisher's exact p-values were obtained to determine statistically significant associations, at a level of0.05. Sixteen percent (95,848/599,093) of all the patients were classified under the breathing problems chief complaint. Of these 95,848 patients, 367 (0.38%) were CA outcomes, and 7.82% (n = 7,493) were BI outcomes.The Cardiac Arrest Quotient (i.e., the number of CA cases as a percentage of the number of patients) for the ECHO priority level was 46 times higher than was that of non-ECHO priority levels: DELTA and CHARLIE (17.05% vs. 0.37%). Asthmatics were associated with CA outcome (OR(95%CI): 0.60(0.47,0.77), p <0.001), but not with BI outcome. The MPDS coding yielded a richer mix of severe outcomes in the higher priority levels.The Severe Respiratory Distress coding had the greatest number of patients and severe outcomes. Future studies that help refine the Severe Respiratory Distress code in the MPDS by more specific subgroups of patients would be beneficial.

Effect of a Medical Priority Dispatch System key question addition in the seizure/convulsion/fitting protocol to improve recognition of ineffective (agonal) breathing

To investigate the impact of a new assessment question in the Medical Priority Dispatch System (MPDS) seizure protocol on the ability of the Emergency Medical Dispatchers (EMDs) to identify the presence of agonal or ineffective breathing. A retrospective comparative study was conducted using two datasets-each representing two versions of the MPDS protocols (version 10.4 and version 11.2) at the London Ambulance Service (LAS). The "before" dataset (April 2004 to March 2005, version 10.4) did not have a specific assessment Key Question to identify the presence of irregular/agonal breathing. The question was added in the "after" dataset (April 2005 to March 2006, version 11.2). The datasets comprised the number of patients, calls, responses, incidents, and outcome (i.e., cardiac arrest [CA] and blue-in [BI]) parameters categorized using MPDS determinant codes. A distribution of these parameters was stratified by protocol version. Two-by-two contingency tables to determine association between ("before" and "after") protocols and CA outcome were generated. The likelihood of classifying CA outcome under the "Not fitting now and breathing regularly (verified)"-protocol 12 ALPHA-level 1 (12-A-1) and combined DELTA descriptor codes, was established. Odds ratios (OR) and p-values at significance level of 0.05 cut-off were used to determine any significant associations. For both datasets, the percentage of the emergency parameters increased with increasing determinant level from ALPHA to DELTA. The percentage of CA outcome in the 12-A-1 descriptor code in protocol version 11.2 was lower than that in version 10.4 (0.18% vs. 0.24%). Within protocol version 11.2, CA outcome was twice more likely in the combined DELTA descriptor codes when compared to other protocol 12 descriptor codes (OR(95%CI): 2.10(1.30, 1.40), p=0.002). The addition of the new assessment question for "breathing regularly" to the dispatch question sequence in the MPDS seizure protocol provides a valuable tool for identifying true cardiac arrest patients. Most of these cases appeared to be specifically captured by the new code 12 DELTA-level 3 (12-D-3): "Irregular Breathing".

The Medical Priority Dispatch System's ability to predict cardiac arrest outcomes and high acuity pre-hospital alerts in chest pain patients presenting to 9-9-9

To establish emergency medical dispatcher (EMD) predictability of cardiac arrest (CA) and high acuity (blue in - BI) outcomes in chest pain patients by using the Medical Priority Dispatch System's (MPDS) priority levels, and its more specific clinical determinant codes. A retrospective descriptive study was done on a one year's worth of aggregate 999 call data comprising number of patients, calls, incidences, and outcomes (as determined by paramedics) obtained from the London Ambulance Service (LAS). We used Fisher's exact test to establish and quantify associations (through odds ratios, 95% CI and p-values) between MPDS priority levels and patient outcomes, stratifying by various pairing of MPDS priority level determinant codes. 11.4% of the total calls were classified under the chest pain protocol (MPDS protocol 10). Of all the CA cases (n=3377), 3.1% (n=106) were classified under the chest pain protocol. MPDS priority levels were significantly associated with CA patient outcome (p=0.030) and BI patient outcome (p<0.001). Only the advanced life support response-levels CHARLIE/DELTA pairing was significantly associated with CA outcome (p=0.010) with CA outcome nearly twice more likely in the combined DELTA-priority level codes. ALPHA/CHARLIE and ALPHA/DELTA-level pairings were significantly associated with BI outcome (p<0.001 each), with increased odds of BI outcome in the CHARLIE and DELTA-priority levels. Clinically, the DELTA-level 4 code demonstrated reduced odds of CA and BI outcome when paired with CHARLIE-level patients, than the other DELTA-level patients. Significant associations existed between patient outcomes, as measured in this study, and the MPDS (UKE version) Protocol 10 (Chest Pain) priority levels and specific determinant codes. The (UKE version) DELTA-level 4 determinant code does not belong in the DELTA-priority level, and should be moved to the CHARLE-level, or eliminated altogether--to bring this protocol version in line with other international versions of the MPDS.

Ability of the Medical Priority Dispatch System Protocol to Predict the Acuity of “Unknown Problem” Dispatch Response Levels

Objective. To determine if Medical Priority Dispatch System's (MPDS's) Protocol 32–Unknown Problem interrogation-based differential dispatch coding distinguishes the acuity of patients as found at the scene by responders, when little (if any) clinical information is known. Methods. “Unknown problem” situations (i.e., all cases not fitting into any other chief complaint group) constitute 5–8% of all calls to dispatch centers. From the total patient encounters (n = 599,107) in the aggregate data of one year (September 2005 to August 2006), we examined 3,947 (0.7%) encounters initially coded as “unknown problem” by the London Ambulance Service Communications Center for the scene presence of cardiac arrest (CA) andparamedic-determined high-acuity (blue-in [BI]/“lights andsiren”) findings. Odds ratios (ORs) with 95% confidence intervals (95% CIs) andp-values were used to assess the degree of associations between determinant codes andcase outcomes (i.e., CA/BI). Results. Statistically significant association between clinical dispatch determinant codes andcase outcomes was observed in the “life status questionable” (LSQ; DELTA-1 [D-1]) andthe “standing, sitting, moving, or talking” (BRAVO-1 [B-1]) code pair for the CA outcome (OR [95% CI]: 0.11 [0, 0.63], p = 0.005) andfor the BI outcome (OR [95% CI]: 0.47 [0.28, 0.77], p = 0.003). The LSQ andall three code pairs (i.e., B-1; “community alarm notifications” [B-2]; and“unknown status” [B-3]) also demonstrated significant associations both with the CA outcome (OR [95% CI]: 0.43 [0.23, 0.81], p = 0.010) andwith the BI outcome (OR [95% CI]: 0.74 [0.56, 0.97], p = 0.033). All the determinant code levels yielded significant association between BI andCA cases. Conclusion. This dispatch protocol for unknown problems successfully differentiates dispatch coding of low-acuity andnon-CA patients only when specific situational information such as the patient's standing, sitting, moving, or talking can be determined during the interrogation process. Also, emergency medical dispatcher (EMD) reliance on caller-volunteered information to identify predefined critical situations does not appear to add to the protocol's ability to differentiate high-acuity andCA patients. LSQ proved to be a better predictor of both CA andBI outcomes, when compared with the BRAVO-level determinant codes within the “unknown problem” chief complaint. The B-3 (completely unknown) determinant code is a better predictor of severe outcomes than nearly all of the clinically similar BRAVO determinant codes in the entire MPDS protocol. Hence, the B-3 coding should be considered—in terms of its predictability for severe outcome—as falling somewhere between a typical DELTA anda typical BRAVO determinant code.

Low Acuity EMS Dispatch Criteria Can Reliably Identify Patients without High-Acuity Illness or Injury

Objective: This retrospective study evaluated the appropriateness of requests assigned the alpha determinant at the time of dispatch by Emergency Medical Dispatchers using the Medical Priority Dispatch System (MPDS). Methods: The primary end point was the proportion of EMS calls assigned the alpha dispatch determinant that resulted in a high-acuity patient encounter. Patient care reports from January 1 to June 30, 2004, were eligible for inclusion; reports with known errors in data entry or those that were not the result of caller interrogation via the 9-1-1 emergency medical dispatch center (EMDC) were excluded. High-acuity patients were defined as those who met trauma triage criteria or received treatment for acute coronary syndrome, respiratory distress, altered mental status, acute stroke, allergic reaction, or abnormal vital signs. Secondary end points included call-processing time, the proportion of included patients who were transported emergently to hospital, andthe adherence of the EMDC to National Academy of Emergency Dispatch (NAED) quality assurance guidelines. Results: There were 23,939 dispatches; 2,703 were recorded as alpha dispatches in the electronic patient care report (ECR), of which 582 were excluded. Twenty-one of 2,121 calls (< 1%) meeting inclusion criteria met high-acuity criteria andwere considered as inappropriate alpha dispatches. Fourteen of 2,121 (< 1%) were transported emergently to the hospital, eight of whom also met the high-acuity criteria. The call-processing time at the 90th percentile was 2 minutes and29 seconds. The EMDC demonstrated 99% compliance with NAED quality assurance standards. Conclusion: The use of standard MPDS protocols can successfully identify patients who do not demonstrate high-acuity illness or injury more than 99% of the time. Key words: emergency medical services communication system; transportation of patients; emergency medical services; triage of patients.

E FFECTIVENESS OF A M EDICAL P RIORITY D ISPATCH P ROTOCOL FOR A BDOMINAL P AIN

Objective. Medical Priority Dispatch System (MPDS) protocols are used to determine the appropriate level of emergency medical services (EMS) response that is sent to care for patients in the prehospital setting. The objective of this study was to determine the proportion of patients with abdominal pain who would benefit from advanced life support (ALS) when called for by these protocols. Methods. All 9-1-1 calls were processed using MPDS protocols to determine whether the patient required ALS or basic life support (BLS) services. Consecutive patients having an ALS response for a chief complaint of abdominal pain were included. Dispatch decisions that did not follow the MPDS protocols, and cases taken to facilities other than the primary study hospitals, were excluded. EMS run sheets and hospital records were reviewed to determine: 1) whether prehospital ALS interventions were required, 2) emergency department (ED) disposition, 3) hospital course, and 4) final diagnosis. Calls were classified according to the need for ALS and the seriousness of the subsequent diagnosis. Data analysis was performed by determining 95% confidence intervals (CIs). Results. Of the 343 patients classified as 1C1 or 1C2 who were transported by ALS during the time period, 227 (67%) were transported to the study hospitals. Nine (4%) were excluded because of inappropriate dispatch, leaving 218 for analysis. Hospital records were available for 186 (86%) cases, of which 12 (6%; CI 3%, 9%) were potentially life-threatening, requiring ALS intervention. Seventeen (9%; CI 5%, 1%) were non-life-threatening, but potentially benefited from ALS intervention. The remaining 157 (84%; CI 79%, 89%) were classified as not requiring ALS. Conclusions. Use of age- and gender-specific MPDS protocols for patients with a chief complaint of abdominal pain results in significant overtriage and overuse of ALS. Steps should be taken to develop key questions that provide more accurate classification of these patients that goes beyond age and gender classification alone.