Transport Time Interval Research Articles

Abstract Su605: Return of Spontaneous Circulation after Transport with Ongoing Cardiopulmonary Resuscitation: Is Transport Always Futile?

Introduction: Despite validated Termination of Resuscitation (TOR) rules for Out of Hospital Cardiac Arrest (OHCA) some OHCA patients are transported prior to Return of Spontaneous Circulation (ROSC), sometimes with long transport times. There are certain therapies unavailable in the prehospital setting which could make transport prior to ROSC beneficial for some OHCA patients. Hypothesis: We hypothesized that longer transport times for patients with ongoing Cardiopulmonary Resuscitation (CPR) would be associated with progressively lower probability of achieving ROSC. Aims: To determine if there is a transport time interval beyond which ROSC becomes so unlikely that transport time could be determinant factor for TOR. Methods: We performed a retrospective study of the 2020-2022 NEMSIS national prehospital dataset. We included adult OHCA patients that did not have ROSC prehospital, were transported to the hospital, and had outcome and timestamp data available. We calculated transport time for each encounter and stratified encounters into 5-minute transport time intervals. We defined our outcome as ROSC after transport. We used multivariable logistic regression evaluating the association between 5-minute increases in transport time and ROSC. We performed a secondary analysis of patients that met termination of resuscitation (TOR) criteria (unwitnessed OHCA with no CPR or AED placement prior to EMS arrival). Results: Of 1,409,692 OHCAs, we included 137,957 OHCAs that were transported without prehospital ROSC. The median transport time was 8.9 minutes (IQR 5.4-13.8), and 17,957 (13.1%) had ROSC after hospital arrival. In 5-minute intervals from 0-30 minutes, ROSC rates were 13.5%, 13.1%, 12.0%, 11.1%, 12.1%, and 13.9%. Odds of ROSC per 5-minute increase in transport time was 1.00 (95% CI 1.00-1.00). For patients that met field TOR criteria, rates of ROSC for each 5-minute interval from 0-30 minutes were 9.2%, 8.7%, 7.6%, 5.9%, 6.1%, 4.2%, 7.5%. Odds of ROSC per 5-minute increase in transport time was 0.93 (95% CI 0.88-0.98). Conclusion: In this dataset we were unable to identify a transport time interval up to 30 mins beyond which transport is futile, even in patients who were transported despite meeting the universal TOR rule. Decision to transport based on case-by-case OHCA characteristics could have influenced results. Further research is needed to identify the subset of patient in whom transport prior to ROSC may be beneficial.

Association of transport time interval with neurologic outcome in out-of-hospital cardiac arrest patients without return of spontaneous circulation on scene and the interaction effect according to prehospital airway management.

ObjectiveThis study analyzed the association of transport time interval (TTI) with survival rate and neurologic outcome in out-of-hospital cardiac arrest (OHCA) patients without return of spontaneous circulation (ROSC) and the interaction effect of TTI according to prehospital airway management.MethodsA retrospective observational study based on the nationwide OHCA database from January 2013 to December 2017 was designed. Emergency medical service (EMS)-treated OHCA patients aged ≥18 years were included. TTI was categorized into four groups of quartiles (≤4, 5–7, 8–11, ≥12 minutes). The primary outcome was favorable neurologic outcome at discharge. The secondary outcome was survival to discharge from the hospital. Multivariable logistic regression was used to analyze outcomes according to TTI. A different effect of TTI according to the administration of prehospital EMS advanced airway was evaluated.ResultsIn total, 83,470 patients were analyzed. Good neurologic recovery decreased as TTI increased (1.0% for TTI ≤4 minutes, 0.9% for TTI 5–7 minutes, 0.6% for TTI 8–11 minutes, and 0.5% for TTI ≥12 minutes; P for trend <0.05). The adjusted odds ratio of prolonged TTI (≥12 minutes) was 0.73 (95% confidence interval, 0.57–0.93; P<0.01) for good neurologic recovery. However, the negative effect of prolonged TTI on neurological outcome was insignificant when advanced airway or entotracheal intubation were performed by EMS providers (adjusted odds ratio, 1.17; 95% confidence interval, 0.42–3.29; P=0.76).ConclusionEMS TTI was negatively associated with the neurologic outcome of OHCA without ROSC on scene. When advanced airway was performed on scene, TTI was insignificantly associated with the outcome.

Association of prehospital airway management technique with survival outcomes of out-of-hospital cardiac arrest patients.

IntroductionDespite numerous studies on airway management in out-of-hospital cardiac arrest (OHCA) patients, the choice of prehospital airway management technique remains controversial. Our study aimed to investigate the association between prehospital advanced airway management and survival outcomes according to a transport time interval (TTI) using nationwide OHCA registry database in Korea.MethodsThe inclusion criteria were patients with OHCA aged over 18 years old with a presumed cardiac etiology between January 2015 and December 2018. The primary outcome was survival to hospital discharge. The main exposure was the prehospital airway management technique performed by the emergency medical technicians (EMTs), classified as bag-valve mask (BVM), supraglottic airway (SGA), or endotracheal intubation (ETI).We performed multivariable logistic regression analysis and interaction analysis between the type of airway management and TTI for adjusted odds ratios (aORs) and 95% confidence intervals (CIs).ResultsOf a total of 70,530 eligible OHCA patients, 26,547 (37.6%), 38,391 (54.4%), and 5,592 (7.9%) were managed with BVM, SGA, ETI, respectively. Patients in the SGA and ETI groups had a higher odds of survival to discharge than BVM groups (aOR, 1.11 (1.05–1.16) and 1.13 (1.05–1.23)). And the rates of survival to discharge with SGA and ETI were significantly higher in groups with TTI more than 8 minutes (1.17 (1.08–1.27) and 1.38 (1.20–1.59)).ConclusionThe survival to discharge was significantly higher among patients who received ETI and SGA than in those who received BVM. The transport time interval influenced the effect of prehospital airway management on the clinical outcomes after OHCA.

P149 Association of prehospital airway management technique with survival outcomes of out-of-hospital cardiac arrest patients according to transport time interval

P149 Association of prehospital airway management technique with survival outcomes of out-of-hospital cardiac arrest patients according to transport time interval

Association between Survival and Time of On-Scene Resuscitation in Refractory Out-of-Hospital Cardiac Arrest: A Cross-Sectional Retrospective Study.

It is estimated that over 60% of out-of-hospital cardiac arrest (OHCA) patients with a shockable rhythm are refractory to current treatment, never achieve return of spontaneous circulation, or die before they reach the hospital. Therefore, we aimed to identify whether field resuscitation time is associated with survival rate in refractory OHCA (rOHCA) with a shockable initial rhythm. This cross-sectional retrospective study extracted data of emergency medical service (EMS)-treated patients aged ≥ 15 years with OHCA of suspected cardiac etiology and shockable initial rhythm confirmed by EMS providers from the OHCA registry database of Korea. A multivariable logistic regression analysis was conducted for survival to discharge and good neurological outcomes in the scene time interval groups. The median scene time interval for the non-survival and survival to discharge patients were 16 (interquartile range (IQR) 13–21) minutes and 14 (IQR 12–16) minutes, respectively. In this study, for rOHCA patients with a shockable rhythm, continuing CPR for more than 15 min on the scene was associated with a decreased chance of survival and good neurological outcome. In particular, we found that in the patients whose transport time interval was >10 min, the longer scene time interval was negatively associated with the neurological outcome.

Spatiotemporal access to emergency medical services in Wuhan, China: accounting for scene and transport time intervals

BackgroundAccess as a primary indicator of Emergency Medical Service (EMS) efficiency has been widely studied over the last few decades. Most previous studies considered one-way trips, either getting ambulances to patients or transporting patients to hospitals. This research assesses spatiotemporal access to EMS at the shequ (the smallest administrative unit) level in Wuhan, China, attempting to fill a gap in literature by considering and comparing both trips in the evaluation of EMS access.MethodsTwo spatiotemporal access measures are adopted here: the proximity-based travel time obtained from online map services and the enhanced two-step floating catchment area (E-2SFCA) which is a gravity-based model. First, the travel time is calculated for the two trips involved in one EMS journey: one is from the nearest EMS station to the scene (i.e. scene time interval (STI)) and the other is from the scene to the nearest hospital (i.e. transport time interval (TTI)). Then, the predicted travel time is incorporated into the E-2SFCA model to calculate the access measure considering the availability of the service provider as well as the population in need. For both access measures, the calculation is implemented for peak hours and off-peak hours.ResultsBoth methods showed a marked decrease in EMS access during peak traffic hours, and differences in spatial patterns of ambulance and hospital access. About 73.9% of shequs can receive an ambulance or get to the nearest hospital within 10 min during off-peak periods, and this proportion decreases to about 45.5% for peak periods. Most shequs with good ambulance access but poor hospital access are in the south of the study area. In general, the central areas have better ambulance, hospital and overall access than peripheral areas, particularly during off-peak periods.ConclusionsIn addition to the impact of peak traffic periods on EMS access, we found that good ambulance access does not necessarily guarantee good hospital access nor the overall access, and vice versa.

Comparing the neurologic outcomes of patients with out-of-hospital cardiac arrest according to prehospital advanced airway management method and transport time interval.

ObjectiveThe incidences of prehospital advanced airway management by emergency medical technicians in South Korea are increasing; however, whether this procedure improves the survival outcomes of patients experiencing out-of-hospital cardiac arrest remains unclear. The present study aimed to investigate the association between prehospital advanced airway management and neurologic outcomes according to a transport time interval (TTI) using the Korean Cardiac Arrest Research Consortium database.MethodsWe retrospectively analyzed the favorable database entries that were prospectively collected between October 2015 and December 2016. Patients aged 18 years or older who experienced cardiac arrest that was presumed to be of a medical etiology and that occurred prior to the arrival of emergency medical service personnel were included. The exposure variable was the type of prehospital airway management provided by emergency medical technicians. The primary endpoint was a favorable neurologic outcome.ResultsOf 1,871 patients who experienced out-of-hospital cardiac arrest, 785 (42.0%), 121 (6.5%), and 965 (51.6%) were managed with bag-valve-mask ventilation, endotracheal intubation (ETI), and supraglottic airway (SGA) devices, respectively. SGAs and ETI provided no advantage in terms of favorable neurologic outcome in patients with TTIs ≥12 minutes (odds ratio [OR], 1.37; confidence interval [CI], 0.65–2.87 for SGAs; OR, 1.31; CI, 0.30–5.81 for ETI) or in patients with TTI <12 minutes (OR, 0.57; CI, 0.31–1.07 for SGAs; OR, 0.63; CI, 0.12–3.26 for ETI).ConclusionNeither the prehospital use of SGA nor administration of ETI was associated with superior neurologic outcomes compared with bag-valve-mask ventilation.

Mechanical Chest Compression Device for Out-Of-Hospital Cardiac Arrest: A Nationwide Observational Study.

There are few studies on the use of a mechanical chest compression (meCC) device during transport in patients with out-of-hospital cardiac arrest (OHCA). The aim of our study was to compare the performance of an meCC device with that of manual chest compression during transport after OHCA. This study used data from the national cardiac arrest registry of patients with OHCA of presumed cardiac etiology. The primary exposure was the use of an meCC device by an Emergency Medical Services provider while transporting a patient to the emergency department. The primary endpoint was good cerebral performance category at discharge. We compared survival and neurologic outcomes between an meCC device group and a manual chest compression group. We also performed an interaction analysis to assess changes in study outcomes of meCC device use by the initial electrocardiogram (ECG) and transport time interval (TTI). Among 30,021 adult patients after OHCA with presumed cardiac etiology, an meCC device was used in 2357 (7.6%). After adjustment for possible confounders, there were no significant differences with respect to good neurologic recovery in the outcomes of patients who were treated with an meCC device and those who received manual chest compression (adjusted odds ratio [AOR] 0.66; 95% confidence interval [CI] 0.43-1.02) and survival to discharge (AOR 0.83; 95% CI 0.64-1.06). In the interaction model, the AOR of the meCC device study outcome did not interact with the initial ECG and TTI. The meCC device did not show better study outcomes than manual compression.

A Comparison of Pre-Hospital Emergency Medical Services’ Response and Duration Times in Urban versus Rural Areas of Saudi Arabia

Background Response impacts on treatment outcomes, particularly for time-sensitive illnesses, including trauma. This study compares key outcome measures for emergency medical services (EMS) operating in urban versus rural areas in the Riyadh region of Saudi Arabia. Methods A cross-sectional study of EMS users was conducted using a random sampling method. Primary outcome measures were response time, on-scene time, transport time interval and survival rates. Secondary outcomes were the length of stay in the intensive care unit and hospital. Data were compared between the urban and rural groups using the t-test and chi-square test. Results Eight-hundred patients (n=400 urban, n=400 rural) were included in the final analysis. Cases in rural areas had significantly higher response times and duration times (median response 15 vs. 22 minutes, median duration 43 vs. 62 minutes). Response times were significantly longer for rural areas for MVC, industrial accidents, medical incidents and trauma, but there was no significant difference in duration time for industrial accidents. While urban areas had significantly shorter response times for all incident types, there was no difference with rural areas in duration time for chest injury, gastrointestinal, neurological or respiratory problems. Conclusion The findings indicate that response time and duration differs between urban and rural locations in a number of key areas. The factors underlying these differences need to be the subject of specific follow-up research in order to make recommendations as to the best way to improve EMS in Saudi Arabia and to close the gap in rural and urban service delivery.

The Effect of Transport Time Interval on Neurological Recovery after Out-of-Hospital Cardiac Arrest in Patients without a Prehospital Return of Spontaneous Circulation.

BackgroundLonger transport adversely affects outcomes in out-of-hospital cardiac arrest (OHCA) patients who do not return to spontaneous circulation (ROSC). The aim of this study was to determine the association between the transport time interval (TTI) and neurological outcomes in OHCA patients without ROSC.MethodsWe analyzed adult OHCA patients with presumed cardiac etiology and without prehospital ROSC from 2012 to 2015. The study population was divided into 2 groups according to STI (short STI [1–5 minutes] and long STI [≥ 6 minutes]). The primary exposure was TTI, which was categorized as short (1–5 minutes), intermediate (6–10 minutes), or long (≥ 11 minutes). The primary outcome was a good neurological recovery at discharge. Multiple logistic regression analysis was used in each STI group.ResultsAmong 57,822 patients, 23,043 (40%), 20,985 (36%), and 13,794 (24%) were classified as short, intermediate, and long TTI group. A good neurological recovery occurred in 1.0%, 0.6%, and 0.3% of the patients in the short, intermediate and long TTI group, respectively. Among 12,652 patients with short STI, a good neurological recovery occurred in 2.2%, 1.0%, and 0.4% of the patients in the short, intermediate and long TTI group, respectively. Among 45,570 patients with long STI, a good neurological recovery occurred in 0.7%, 0.5%, and 0.3% of the patients in the short, intermediate and long TTI group, respectively. When short TTI was used as a reference, the adjusted odds ratios (AOR) of TTI for good neurological recovery was different between short STI group and long STI group (AOR [95% confidence interval, 0.46 [0.32–0.67] vs. 0.72 [0.59–0.89], respectively, for intermediate TTI and 0.31 [0.17–0.55] vs. 0.49 [0.37–0.65], respectively, for long TTI).ConclusionA longer TTI adversely affected the likelihood of a good neurological recovery in OHCA patients without prehospital ROSC. This negative effect was more prominent in short STI group.

Road traffic injuries in Uganda: pre-hospital care time intervals from crash scene to hospital and related factors by the Uganda Police

A cross-sectional survey was conducted to collect primary data prospectively on pre-hospital care time intervals of Road Traffic Crash (RTC) victims that had been rescued by the Uganda police and to determine what factors were related to those intervals. The survey was conducted between 1 May 2015 and 31 May 2015. The Police responses to 96 RTCs were recorded, but only 74 of them were considered serious enough to warrant hospital transfer, and those 74 are the subject of the analysis. Pre-hospital care time ranged between 10 and 220 min. Seventy-two per cent of the calls were completed within 1 h of call initiation. The scene to hospital transport interval was the longest with a mean of 19.07 min (SD 10.11). Activation time was the shortest interval with a mean of 4.58 min (SD 5.67). Key factors for delays included: understaffing, lack of skills and long distances. A toll-free Universal Access Number, a law mandating provision of free basic emergency medical services at every health facility and gazetting of lanes for emergency services and might decrease on pre-hospital care time and could reduce on the notification and transport time interval respectively.

Implementation trial of the basic life support termination of resuscitation rule: Reducing the transport of futile out-of-hospital cardiac arrests

BackgroundThe basic life support (BLS) termination of resuscitation (TOR) rule recommends transport and continued resuscitation when cardiac arrest is witnessed by EMT-Ds, or there is a return of spontaneous circulation, or a shock is given, and prior studies have suggested the transport rate should fall to 37%. Methods and resultsThis real-time prospective multi-center implementation trial evaluated the BLS TOR rule for compliance, transport rate and provider and physician comfort. Both provider and physician noted their decision-making rationale and ranked their comfort on a 5-point Likert scale. Functional survival was measured at discharge. Of 2421 cardiac arrests, 953 patients were eligible for the rule, which was applied correctly for 755 patients (79%) of which 388 were terminated. 565 patients were transported resulting in a reduction of the transport rate from 100% (historical control) to 59% (p<0.001). The BLS TOR rule was not followed in 198 eligible patients (21%) and they were all transported despite meeting the criteria to terminate. Providers cited 241 reasons for non-compliance: family distress, short transport time interval, younger age and public venue. All 198 transported patients, non-compliant with the rule, died. Both providers and physicians were comfortable with using the rule to guide TOR (median [IQR] of 5 [4,5]; p<0.001). ConclusionsThis implementation trial confirmed the accuracy of the BLS TOR rule in identifying futile out-of-hospital cardiac arrest (OHCA) resuscitations, significantly reduced the transport rate of futile OHCA and most providers and physicians were comfortable following the rule's recommendations.

Does out-of-hospital EMS time affect trauma survival?

To determine if out-of-hospital emergency medical services (EMS) time intervals are associated with unexpected survival and death in urban major trauma, a retrospective review was conducted of major trauma cases entered into an urban trauma system by an EMS system during a one-year period. Patients with unexpected death or unexpected survival were identified using TRISS methodology. The EMS response, on-scene time, transport time, and total EMS out-of-hospital time intervals were compared for the two groups using the unpaired t test (two-tailed analysis). Of 848 major trauma cases, there were 13 (1.5%) unexpected survivors and 20 (2.4%) unexpected deaths. Of those patients with complete EMS times, the mean out-of-hospital response time interval was significantly shorter for the unexpected survivors (3.5 +/- 1.2 minutes v 5.9 +/- 4.3 minutes; P = .04). The mean EMS on-scene time interval (7.8 +/- 4.1 minutes v 11.6 +/- 6.5 minutes; P = .06) and the mean transport time interval (9.5 +/- 4.4 minutes v 11.7 +/- 4.0 minutes; P = .17) also favored the unexpected survivor group. Overall, the total EMS time interval was significantly shorter for unexpected survivors (20.8 +/- 5.2 minutes v 29.3 +/- 12.4 minutes; P = .02). It was concluded that a short overall out-of-hospital time interval may positively affect patient survival in selected urban major trauma patients.

Modeling kinetic non-equilibrium using the first two moments of the residence time distribution

A method for simulating field scale transport of kinetically adsorbing solutes is described. The non-equilibrium adsorption is modeled as a birth and death process and is coupled with the particle tracking approach using the first two moments of the distribution of the particle residence time, i.e., the time that a solute particle stays in the liquid phase. A single residence time distribution, regardless of the initial and final phase, is demonstrated to yield an accurate description of chemical kinetics in the vast majority of field scale problems. The first two moments of the residence time distribution are derived as a function of chemical reaction rates and the transport time interval Δt. It is shown that the first moment of the residence time represents a measure of the speed of the chemical reaction relative to the transport time scale Δt which is chosen depending on the velocity field. The second moment of the residence time reflects the relative importance of the chemical kinetics versus local equilibrium conditions for the given transport time step Δt. The simulated spatial moments of the contaminant plume are compared in the one-dimensional case with available analytical solutions to demonstrate the accuracy of the proposed technique. A two-dimensional case for stratified formations is presented to study the transport behavior for heterogeneous velocity fields and variable distribution coefficient, hypothesized as being negatively correlated with hydraulic conductivity. The results show that the enhanced plume spreading and the statistics of the arrival time distribution appear to be more sensitive to the spatially variable distribution coefficient than to the kinetics alone. In fact, the second spatial moment was almost doubled in the case of spatially variable distribution coefficient.

A derivation of the macroscopic solute transport equation for homogeneous, saturated, porous media

The macroscopic transport equation for a conservative solute in a homogeneous, water‐saturated porous medium is derived on the basis of a rigorous cumulant expansion applied to the equation of mass balance. The essential physical concept underlying the derivation is that of a local volume‐averaged solute velocity which fluctuates on a time scale that is orders of magnitude smaller than its autocorrelation time scale, which, in turn, is much smaller than the time scale of interest in a typical solute transport experiment. This clear separation of time scales is illustrated with representative data on solute transport in homogeneous, water‐saturated soils and is employed to justify the truncation of an exact cumulant expansion of the divergence of the volume‐averaged solute mass flux density. With the cumulant expansion terminated at first order in the ratio of the solute velocity autocorrelation time to the macroscopic solute transport time interval, an expression for the macroscopic solute mass flux density is produced which is the same as Fick's Law extended to porous media.