Physician-staffed Helicopter Research Articles

Clinical impact of helicopter transport with a physician in cardiogenic shock complicating acute coronary syndrome

Abstract Introduction Cardiogenic shock (CS) remains the leading cause of death in patients with acute coronary syndrome (ACS). Helicopter transport with a physician may improve the prognosis through reduction of the ischemic time and an early critical care. However, the impact of transfer of a physician-staffed helicopter and outcomes of CS complicating ACS is uncertain. Purpose The aim of the present study was to evaluate compare the clinical characteristics and long-term outcome between helicopter transport with a physician and ground transport in CS complicating ACS patients. Methods We retrospectively investigated 2324 consecutive patients with ACS who underwent primary percutaneous coronary intervention (pPCI) in our institution from January 2004 to December 2017. The primary outcome was cardiovascular (CV) death. Results Among the 2324 eligible patients, 273 ACS patients (11.7%) were complicated by CS. Of 273 CS complicating ACS, a total of 81 (29.7%) patients were transported by helicopter, 166 (60.8%) patients were transported by ambulance, and 26 (9.5%) patients did not use emergency medical service. The mean age was 71 years, 75% of patients were male, STEMI was seen in 87%, and mechanical circulatory support was used in 64%. Kaplan-Meier analysis showed that CV mortality up to 30 days was significantly lower with helicopter transport group compared those with ground transport (P = 0.0407). The rate of long-term CV death was comparable between groups (P = 0.19). Multivariate Cox regression analysis showed helicopter transport was significantly associated with lower 30-day CV mortality (adjusted HR 0.56, 95%CI 0.32-0.99, P = 0.0447). Conclusions Helicopter transport with a physician may improve cardiovascular outcomes of CS complicating ACS.Figure 1.Figure 2.

Convulsive Patients Transported by a Physician-staffed Helicopter in Japan Had Better Outcomes in the Keyword-triggered Dispatch Compared to Postcontact Emergency Medical Technician-triggered Dispatch

Abstract Introduction: We retrospectively analyzed convulsive patient outcomes transported by a physician-staffed Helicopter Emergency Medical Service (doctor helicopter [DH]) using the keyword-triggered dispatch with data from the Japan DH Registry System (JDRS). Upon receiving an emergency call containing critical keywords, such as an ongoing convulsion at the firefighting central command room, immediate dispatch of the DH is requested, in addition to dispatching an ambulance. The keyword-triggered dispatch relied on data obtained from the JDRS. Methods: Details from the JDRS database included patient age, sex, cardiac arrest presence upon DH contact, vital signs, DH dispatch timing (keyword-triggered dispatch/emergency medical technician [EMT]-triggered dispatch), medical intervention details, and 1-month outcomes (cerebral performance category [CPC]; CPC1, 2: Good; CPC 3–5: Poor). Subjects were divided into keyword (keyword-triggered dispatch) and control (EMT-triggered dispatch) groups for comparison. Results: Of 1201 patients, all evacuated from the scene, 617 were in the keyword group, and 584 in the control group. No significant differences existed between groups for cardiac arrest, respiratory and heart rates, CPC, or mortality. The keyword group had lower average age, systolic blood pressure, and medical intervention ratio but a higher median Glasgow Coma Scale and good outcome ratio. Conclusion: This first report on the keyword-triggered dispatch as a prognostic factor for convulsive patients evacuated by DH using the JDRS.

A scenario based approach to optimizing cost-effectiveness of physician-staffed Helicopter Emergency Medical Services compared to ground-based Emergency Medical Services in Finland

ObjectivesSince Helicopter Emergency Medical Services (HEMS) is an expensive resource in terms of unit price compared to ground-based Emergency Medical Service (EMS), it is important to further investigate which methods would allow for the optimization of these services. The aim of this study was to evaluate the cost-effectiveness of physician-staffed HEMS compared to ground-based EMS in developed scenarios with improvements in triage, aviation performance, and the inclusion of ischemic stroke patients.MethodsIncremental cost-effectiveness ratio (ICER) was assessed by comparing health outcomes and costs of HEMS versus ground-based EMS across six different scenarios. Estimated 30-day mortality and quality-adjusted life years (QALYs) were used to measure health benefits. Quality-of-Life (QoL) was assessed with EuroQoL instrument, and a one-way sensitivity analysis was carried out across different patient groups. Survival estimates were evaluated from the national FinnHEMS database, with cost analysis based on the most recent financial reports.ResultsThe best outcome was achieved in Scenario 3.1 which included a reduction in over-alerts, aviation performance enhancement, and assessment of ischemic stroke patients. This scenario yielded 1077.07–1436.09 additional QALYs with an ICER of 33,703-44,937 €/QALY. This represented a 27.72% increase in the additional QALYs and a 21.05% reduction in the ICER compared to the current practice.ConclusionsThe cost-effectiveness of HEMS can be highly improved by adding stroke patients into the dispatch criteria, as the overall costs are fixed, and the cost-effectiveness is determined based on the utilization rate of capacity.

Development and internal validation of an algorithm for estimating mortality in patients encountered by physician-staffed helicopter emergency medical services

BackgroundSeverity of illness scoring systems are used in intensive care units to enable the calculation of adjusted outcomes for audit and benchmarking purposes. Similar tools are lacking for pre-hospital emergency medicine. Therefore, using a national helicopter emergency medical services database, we developed and internally validated a mortality prediction algorithm.MethodsWe conducted a multicentre retrospective observational register-based cohort study based on the patients treated by five physician-staffed Finnish helicopter emergency medical service units between 2012 and 2019. Only patients aged 16 and over treated by physician-staffed units were included. We analysed the relationship between 30-day mortality and physiological, patient-related and circumstantial variables. The data were imputed using multiple imputations employing chained equations. We used multivariate logistic regression to estimate the variable effects and performed derivation of multiple multivariable models with different combinations of variables. The models were combined into an algorithm to allow a risk estimation tool that accounts for missing variables. Internal validation was assessed by calculating the optimism of each performance estimate using the von Hippel method with four imputed sets.ResultsAfter exclusions, 30 186 patients were included in the analysis. 8611 (29%) patients died within the first 30 days after the incident. Eleven predictor variables (systolic blood pressure, heart rate, oxygen saturation, Glasgow Coma Scale, sex, age, emergency medical services vehicle type [helicopter vs ground unit], whether the mission was located in a medical facility or nursing home, cardiac rhythm [asystole, pulseless electrical activity, ventricular fibrillation, ventricular tachycardia vs others], time from emergency call to physician arrival and patient category) were included. Adjusted for optimism after internal validation, the algorithm had an area under the receiver operating characteristic curve of 0.921 (95% CI 0.918 to 0.924), Brier score of 0.097, calibration intercept of 0.000 (95% CI -0.040 to 0.040) and slope of 1.000 (95% CI 0.977 to 1.023).ConclusionsBased on 11 demographic, mission-specific, and physiologic variables, we developed and internally validated a novel severity of illness algorithm for use with patients encountered by physician-staffed helicopter emergency medical services, which may help in future quality improvement.

Effect of Daytime versus Nighttime on Prehospital Care and Outcomes after Severe Traumatic Brain Injury.

Background/Objectives: Severe traumatic brain injury (TBI) is a frequent cause of morbidity and mortality worldwide. In the Netherlands, suspected TBI is a criterion for the dispatch of the physician-staffed helicopter emergency medical services (HEMS) which are operational 24 h per day. It is unknown if patient outcome is influenced by the time of day during which the incident occurs. Therefore, we investigated the association between the time of day of the prehospital treatment of severe TBI and 30-day mortality. Methods: A retrospective analysis of prospectively collected data from the BRAIN-PROTECT study was performed. Patients with severe TBI treated by one of the four Dutch helicopter emergency medical services were included and followed up to one year. The association between prehospital treatment during day- versus nighttime, according to the universal daylight period, and 30-day mortality was analyzed with multivariable logistic regression. A planned subgroup analysis was performed in patients with TBI with or without any other injury. Results: A total of 1794 patients were included in the analysis, of which 1142 (63.7%) were categorized as daytime and 652 (36.3%) as nighttime. Univariable analysis showed a lower 30-day mortality in patients with severe TBI treated during nighttime (OR 0.74, 95% CI 0.60-0.91, p = 0.004); this association was no longer present in the multivariable model (OR 0.82, 95% CI 0.59-1.16, p = 0.262). In a subgroup analysis, no association was found between mortality rates and the time of prehospital treatment in patients with combined injuries (TBI and any other injury). Patients with isolated TBI had a lower mortality rate when treated during nighttime than when treated during daytime (OR 0.51, 95% CI 0.34-0.76, p = 0.001). Within the whole cohort, daytime versus nighttime treatments were not associated with differences in functional outcome defined by the Glasgow Outcome Scale. Conclusions: In the overall study population, no difference was found in 30-day mortality between patients with severe TBI treated during day or night in the multivariable model. Patients with isolated severe TBI had lower mortality rates at 30 days when treated at nighttime.

The characteristics and clinical outcomes of trauma patients transferred by a physician-staffed helicopter emergency medical service in Korea: a retrospective study.

Helicopter transport with medical teams has been proven to be effective, with improvements in patient survival rates. This study compared and analyzed the clinical characteristics and treatment outcomes of trauma patients transported by doctor helicopters according to whether patients were transferred after a clinical evaluation or without a clinical evaluation. This study retrospectively reviewed data from the Korean Trauma Data Bank of trauma patients who arrived at a regional trauma center through doctor helicopters from January 1, 2014, to December 31, 2022. The patients were divided into two groups: doctor helicopter transport before evaluation (DHTBE) and doctor helicopter transport after evaluation (DHTAE). These groups were compared. The study population included 351 cases. At the time of arrival at the trauma center, the systolic blood pressure was significantly lower in the DHTAE group than in the DHTBE group (P=0.018). The Injury Severity Score was significantly higher in the DHTAE group (P<0.001), and the accident to trauma center arrival time was significantly shorter in the DHTBE group (P<0.001). Mortality did not show a statistically significant between-group difference (P=0.094). Surgical cases in the DHTAE group had a longer time from the accident scene to trauma center arrival (P=0.002). The time from the accident to the operation room or from the accident to angioembolization showed no statistically significant differences. DHTAE was associated with significantly longer transport times to the trauma center, as well as nonstatistically significant trends for delays in receiving surgery and procedures, as well as higher mortality. If severe trauma is suspected, air transport to a trauma center should be requested immediately after a simple screening test (e.g., mechanism of injury, Glasgow Coma Scale, or Focused Assessment with Sonography in Trauma), which may help reduce the time to definitive treatment.

Prehospital Care of Severely Intoxicated Patients by a Dutch Physician-Staffed Helicopter Emergency Medical Services: A Retrospective Study

ObjectiveIntoxicated patients are often encountered by emergency medical services (eg, in cases of recreational drug use, accidental ingestion, or inhalation of toxic substances or [attempted] suicide). Earlier research showed that a physician-staffed helicopter emergency medical service (P-HEMS) is regularly dispatched for intoxicated patients. However, it is still unclear if there is added value of P-HEMS compared with standard care provided by an ambulance crew. The aim of this study was to analyze the contribution of additional expertise and equipment that P-HEMS brings to the prehospital scene. MethodsIn this retrospective study, we searched the database of the helicopter emergency medical service Lifeliner 1 serving the northwestern quadrant of the Netherlands for cases that involved intoxications from January 2013 to July 2020. Patients were included in this study if the primary reason for P-HEMS dispatch was intoxication. The types of intoxication were categorized as (illicit/recreational) drug related, suicide attempt, or accidental. The agents were categorized as stimulants, depressants, hallucinogenic, cannabinoids, and other substances such as bleach or insulin. Patient characteristics, vital signs, and the therapeutic interventions performed were recorded for analysis. ResultsIn our study period, P-HEMS was dispatched 23,878 times. Of these dispatches, a total of 259 cases were included for further analysis. The majority of patients were male (64.5%). Sixty-six patients (25.5%) had an intoxication of depressant agents alone, whereas 60 patients (23.2%) had an intoxication with a combination of agents. With 159 (61.4%) patients, the majority of cases involved recreational drug intoxications. Unintentional intoxications were treated in 27 (10.4%) patients, whereas 73 (28.2%) cases involved suicide attempts. In 159 patients (61.4%), prehospital endotracheal intubation was required; the vast majority was performed by the helicopter emergency medical service physician. Specific antidotes were administered in 56 (21.6%) of the cases. ConclusionIn this study, we found that P-HEMS crews might complement usual prehospital care by ambulance crews for patients with severe intoxications by bringing advanced skills (eg, airway management and specific antidotes) to the scene.

Outcomes of patients with head injuries transported by a physician-staffed helicopter using the keyword method in Japan.

Outcomes of patients with head injuries transported by a physician-staffed helicopter using the keyword method in Japan.

The Estimated Cost-Effectiveness of Physician-Staffed Helicopter Emergency Medical Services Compared to Ground-Based Emergency Medical Services in Finland

ObjectiveBecause the unit cost of helicopter emergency medical services (HEMS) is higher than traditional ground-based emergency medical services (EMS), it is important to further investigate the impact of HEMS. The aim of this study was to evaluate the cost-effectiveness of physician-staffed HEMS compared with ground-based EMS in Finland under current practices. MethodsThe incremental cost-effectiveness ratio was evaluated using the differences in outcomes and costs between HEMS and ground-based EMS. The estimated mortality within 30 days and quality-adjusted life years (QALYs) were used to measure health benefits. Quality of life was estimated according to the EuroQoL scale, and a 1-way sensitivity analysis was conducted on the QALY indexes ranging from 0.6 to 0.8. Survival rates were calculated according to the national HEMS database, and the cost structure was estimated at 48 million euros based on financial statements. ResultsHEMS prevented the 30-day mortality of 68.1 patients annually, with an incremental cost-effectiveness ratio of €43,688 to €56,918/QALY. Fixed costs accounted for 93% of HEMS expenses because of 24/7 operations, making the capacity utilization rate a major determinant of total costs. ConclusionHEMS intervention is cost-effective compared with ground-based EMS and is acceptable from a societal willingness-to-pay perspective. These findings contribute valuable insights for health care management decision making and highlight the need for future research for service optimization.

Prehospital interventions and outcomes in traumatic cardiac arrest: a population-based cohort study using the Danish Helicopter Emergency Medical Services data.

Traumatic cardiac arrest is associated with poor prognosis, and timely evidence-based treatment is paramount for increasing survival rates. Physician-staffed helicopter emergency medical service use in major trauma has demonstrated improved outcomes. However, the sparsity of data highlights the necessity for a comprehensive understanding of the epidemiology of traumatic cardiac arrest. The primary objective of the present study was to evaluate survival and return of spontaneous circulation (ROSC) and to investigate the characteristics of patients with traumatic cardiac arrest assessed by the Danish HEMS. This was a population-based cohort study based on data from the Danish helicopter emergency medical service database. The study included all patients assessed by the Danish helicopter emergency medical services between 2016 and 2021. Data were analysed using descriptive statistics, non-parametric testing and logistic regression analyses. Descriptive analysis of prehospital interventions included cardiopulmonary resuscitation, defibrillation, airway management, administration of blood products, and thoracic decompression. The primary outcome was 30-day survival, and the key secondary outcome was prehospital ROSC. A total of 223 patients with TCA were included. The median age was 54 years (IQR 34-68), and the majority were males. Overall, 23% of patients achieved prehospital ROSC, and the 30-day survival rate was 4%. Factors associated with an increased likelihood of ROSC were an initial shockable cardiac rhythm, odds ratio (OR) of 3.78 (95% CI 1.33-11.00) and endotracheal intubation, OR 7.10 (95% CI 2.55-22.85). This study highlights the low survival rates observed among patients with traumatic cardiac arrest assessed by helicopter emergency medical services. The findings support the positive impact of an initial shockable cardiac rhythm and endotracheal intubation in improving the likelihood of ROSC. The study contributes to the limited literature on traumatic cardiac arrests assessed by physician-staffed helicopter emergency services. Finally, the findings emphasise the need for further research to understand and improve outcomes in this subgroup of cardiac arrest.

Patients With Atrioventricular Block Transported by a Physician-Staffed Helicopter in Japan From 2015 to 2020

ObjectiveWe retrospectively investigated the current status of patients with atrioventricular block (AVB) who had been transported by the physician-staffed helicopter emergency medical service and their final outcome using data from the Japan Doctor Helicopter Registry (JDHR) system. MethodsThe following details of the dispatch activity were collected from the database of the JDHR: age and sex, vital signs when emergency medical technicians encountered the patient at the scene and on arrival at the receiving hospitals, contents of the medical intervention, new cardiac arrest during transportation, the main etiology of AVB, and the number of deaths in 1 month. The changes in vital signs between the scene and upon arrival at the hospital were compared. ResultsA total of 99 patients had complete AVB. The average age of the patients was 75 years, and there was a male predominance. All subjects were evacuated from the scene. Among the 62 subjects who received the drugs, 18 received atropine. Six patients underwent percutaneous pacing. None of the patients developed a new cardiac arrest during transportation. The average Glasgow Coma Scale score and heart rate upon arrival at the hospital were significantly greater than those at the scene. ConclusionThe present study showed the current status of patients with AVB who were transported by a doctor helicopter using registry data from the JDHR. The present findings suggest that a doctor helicopter could provide safe transportation for patients with AVB.

Usefulness of Key Word Methods to Execute Early Requests for a Physician-Staffed Helicopter Emergency Medical Service Dispatch to Facilitate Early Medical Intervention by Physicians

ObjectiveA physician-staffed helicopter emergency medical service is called a doctor helicopter (DH) in Japan. We retrospectively investigated this service using a data bank provided by the Japan DH registry system. MethodsThe following details of the dispatch activity were collected: patient age and sex, vital signs (Japan Coma Scale [JCS], systolic blood pressure, heart rate, and respiratory rate) at the scene measured by emergency medical technicians (EMTs), dispatch of the DH before the EMTs made contact with patients (key words group) or after (control group), and the survival outcome at 1 month. ResultsDuring the investigation period, 28,357 patient records were analyzed (key words group, n = 13,861; control group, n = 14,496). The age, JCS, and respiratory rate were significantly smaller in the key words group than in the control group. The rates of male sex and survival in the key words group were significantly greater than those in the control group. In the multivariate analysis, dispatch of the DH after EMTs made contact with the patients (odds ratio [OR] = 0.72; 95% confidence interval [CI], 0.55-0.92), female sex (OR = 0.86; 95% CI, 0.75-0.98), older age (OR = 0.97; 95% CI, 0.96-0.97), elevated respiratory rate (OR = 0.97; 95% CI, 0.97-0.98), and high JCS (OR = 0.99; 95% CI, 0.99-0.99) were associated with a decreased 1-month survival (P > .0001). ConclusionThis is the first report to describe the key words method as a potential factor influencing optimal outcomes/potential survival rates in patients evacuated by the DH using the JDRS. Our study results suggest that the firefighting central command room should consider adopting the key words method when the helicopter emergency medical service is used.

Explainable Prediction Model of the Need for Emergency Hemostasis Using Field Information During Physician-Staffed Helicopter Emergency Medical Service Interventions: A Single-Center, Retrospective, Observational Pilot Study

ObjectiveEarly recognition of hemostasis is important to prevent trauma-related deaths. We conducted a pilot study of a predictive model of hemostatic need using factors that can be collected during helicopter emergency medical service (HEMS) interventions until transport hospital selection using cases from our institution. MethodsThis single-center, retrospective, observational pilot study included 251 trauma patients aged ≥ 18 years treated with HEMS between April 2017 and March 2022, in Nara Medical University. Cardiac arrest and pre-HEMS treatment patients were excluded. Emergency hemostatic surgery prediction models were constructed using the light gradient boosting machine cross-validation method using objective data that could be collected before hospital determination. The accuracy of this model was compared with that of the ground emergency medical service–based model, and factors influencing outcome were visualized using Shapley additive explanations. ResultsThe predictive accuracy of the model with HEMS intervention factors was an area under the receiver operating characteristic curve of 0.80, superior to the 0.73 accuracy area under the receiver operating characteristic curve for ground emergency medical services constructed with contact information. Clinically important factors, such as shock index, blood pressure changes, and ultrasound findings, had a significant impact on outcomes, with nonmonotonic effects observed across factors. ConclusionThis pilot study suggests that predictive models of emergency hemostasis can be built using limited prehospital information. To validate this model, a larger, multicenter study is recommended.

Factors influencing on-scene time in a physician-staffed helicopter emergency medical service (HEMS): a retrospective observational study

BackgroundFor helicopter emergency service systems (HEMS), the prehospital time consists of response time, on-scene time and transport time. Little is known about the factors that influence on-scene time or about differences between adult and paediatric missions in a physician-staffed HEMS.MethodsWe analysed the HEMS electronic database of Swiss Air-Rescue from 01-01-2011 to 31-12-2021 (N = 110,331). We included primary missions and excluded missions with National Advisory Committee for Aeronautics score (NACA) score 0 or 7, resulting in 68,333 missions for analysis. The primary endpoint ‘on-scene time’ was defined as first physical contact with the patient until take-off to the hospital. A multivariable linear regression model was computed to examine the association of diagnosis, type and number of interventions and monitoring, and patient's characteristics with the primary endpoint.ResultsThe prehospital time and on-scene time of the missions studied were, respectively, 50.6 [IQR: 41.0–62.0] minutes and 21.0 [IQR: 15.0–28.6] minutes. Helicopter hoist operations, resuscitation, airway management, critical interventions, remote location, night-time, and paediatric patients were associated with longer on-scene times.ConclusionsCompared to adult patients, the adjusted on-scene time for paediatric patients was longer. Besides the strong impact of a helicopter hoist operation on on-scene time, the dominant factors contributing to on-scene time are the type and number of interventions and monitoring: improving individual interventions or performing them in parallel may offer great potential for reducing on-scene time. However, multiple clinical interventions and monitoring interact and are not single interventions. Compared to the impact of interventions, non-modifiable factors, such as NACA score, type of diagnosis and age, make only a minor contribution to overall on-scene time.

Differential diagnosis and cause-specific treatment during out-of-hospital cardiac arrest: a retrospective descriptive study

BackgroundThe cardiopulmonary resuscitation (CPR) guidelines recommend identifying and correcting the underlying reversible causes of out-of-hospital cardiac arrest (OHCA). However, it is uncertain how often these causes can be identified and treated. Our aim was to estimate the frequency of point of care ultrasound examinations, blood sample analyses and cause-specific treatments during OHCA.MethodsWe performed a retrospective study in a physician-staffed helicopter emergency medical service (HEMS) unit. Data on 549 non-traumatic OHCA patients who were undergoing CPR at the arrival of the HEMS unit from 2016 to 2019 were collected from the HEMS database and patient records. We also recorded the frequency of ultrasound examinations, blood sample analyses and specific therapies provided during OHCA, such as procedures or medications other than chest compressions, airway management, ventilation, defibrillation, adrenaline or amiodarone.ResultsOf the 549 patients, ultrasound was used in 331 (60%) and blood sample analyses in 136 (24%) patients during CPR. A total of 85 (15%) patients received cause-specific treatment, the most common ones being transportation to extracorporeal CPR and percutaneous coronary intervention (PCI) (n = 30), thrombolysis (n = 23), sodium bicarbonate (n = 17), calcium gluconate administration (n = 11) and fluid resuscitation (n = 10).ConclusionIn our study, HEMS physicians deployed ultrasound or blood sample analyses in 84% of the encountered OHCA cases. Cause-specific treatment was administered in 15% of the cases. Our study demonstrates the frequent use of differential diagnostic tools and relatively infrequent use of cause-specific treatment during OHCA. Effect on protocol for differential diagnostics should be evaluated for more efficient cause specific treatment during OHCA.

Outcome in intoxicated patients transported by a physician-staffed helicopter in Japan from 2015 to 2020.

We retrospectively investigated the current status of poisoned patients who had been transported by a physician-staffed helicopter emergency medical service and their final outcomes using data from the JAPAN DOCTOR HELICOPTER REGISTRY SYSTEM. The following details of dispatch activity were collected from the database of the JAPAN DOCTOR HELICOPTER REGISTRY SYSTEM: patient age and sex, timing of dispatch request, presence of cardiac arrest, vital signs, medical intervention, main etiology of intoxication, and final outcome. The patients were divided into two groups: those with a good outcome and those with a poor outcome. The variables were compared between the two groups. A total of 336 patients were intoxicated. Psychotropic drug overdose was the dominant cause, followed by carbon monoxide and ethanol. The median Glasgow Coma Scale score was significantly higher in the good outcome group than in the poor outcome group. The rates of cardiac arrest, interventions to secure an airway and/or assist with ventilation, and drug administration were significantly lower in the good outcome group than in the poor outcome group. There were no records concerning the decontamination of the intoxicating substance at the scene or during air evacuation. The study suggests that various factors may influence the outcomes of patients with different types of intoxication. These findings offer valuable insights that could help to establish effective treatment strategies and the operation of doctor helicopters for intoxicated patients.

A Clue Supporting a Diagnosis of Atlanto-Occipital Dislocation Based on a Traumatic Vacuum Phenomenon.

Sir, The high spatial and densitometric resolution of computed tomography (CT) means that it frequently shows gas (vacuum phenomenon [VP]) in tissues. VP is observed at locations that experience traumatic impact; thus, an analysis of VP may be useful for elucidating the mechanism of injury.[1] The mechanism responsible for the formation of VP is as follows: if an enclosed tissue space is allowed to expand as a rebound phenomenon after an external impact, the volume within the enclosed space will increase. In the setting of expanding volume, the pressure within the space will decrease. The solubility of the gas in the enclosed space will decrease as the pressure of the space decreases. Decreased solubility allows a gas to leave a solution. We herein report a patient in whom VP was detected near the foramen magnum after blunt trauma that resulted in a successful diagnosis of atlanto-occipital dislocation. The patient was a 53-year-old man who suddenly crashed while motorcycling on a passing lane of a national route. He was thrown from the vehicle and hit a guardrail on the median. At 16 min from the first call, emergency medical technicians reached him. He was in cardiac arrest at the time, and the initial rhythm was asystole. Bystander basic life support was absent. He was bleeding from the nose and mouth. He was transported to the grounds of a nearby elementary school and evacuated by a physician-staffed helicopter. On arrival, he remained in cardiac arrest. He underwent resuscitative thoracotomy, but it failed to obtain the return of spontaneous circulation. Autopsy CT showed subarachnoid hemorrhaging at the basal cistern and posterior fossa. A sagittal view of the skull and cervical bone on CT did not show any fracture or dislocation. However, he had several small gas densities at the deep neck area near the posterior foramen magnum [Figure 1], so the complication of atlanto-occipital dislocation was suspected. Autopsy imaging of magnetic resonance imaging showed atlanto-occipital dislocation compressing the junction between the medulla and spinal cord [Figure 1].Figure 1: Sagittal view of computed tomography (CT, left and middle) with bony field and magnetic resonance imaging (MRI, short-tau inversion recovery image) on arrival. The CT showed several small gas densities (white triangle) at the deep neck area near the posterior foramen magnum without fracture or dislocation. MRI showed atlanto-occipital dislocation (black triangle) compressing the junction between the medulla and spinal cord. The airway was shifted frontally by a hematoma (star). CT: Computed tomography, MRI: Magnetic resonance imagingThis is the first case report, wherein VP near the foramen magnum was a clue supporting a diagnosis of atlanto-occipital dislocation. The diagnosis of atlanto-occipital dislocation by imaging is not easy, and indeed, one report showed no correct diagnoses of atlanto-occipital dislocation when patients were in cardiac arrest.[2,3] Overlooking atlanto-occipital dislocation can result in a fatal outcome.[4] Accordingly, physician should strongly suspect the complication of atlanto-occipital dislocation when patients have traumatic VP near the foramen magnum on CT. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent form. In the form, the patient’s family has given his consent for his image and other clinical information to be reported in the journal. The patient’s family understands that his name and initial will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Research quality and ethics statement The authors followed applicable EQUATOR Network (https:// www.equator-network.org/) guidelines, notably the CARE guideline, during the conduct of this report. Financial support and sponsorship This work was supported in part by a Grant-in-Aid for Special Research in Subsidies for ordinary expenses of private schools from The Promotion and Mutual Aid Corporation for Private Schools of Japan. Conflicts of interest There are no conflicts of interest.

Outcomes of patients with decompression illness transported by physician-staffed helicopter according to Japanese Registry data (2015-2020).

No nationwide reports have focused on patients with decompression illness (DCI) transported by doctor helicopter (DH) in Japan. We performed this retrospective study to examine this population using data from the Japan DH registry system (JDRS). Patients were initially selected from the JDRS database. They were divided into two groups: those transported by the Eastern Shizuoka DH (ES-DH) and those transported by other DHs. Variables were compared between the two groups. There were 44 patients who had DCI out of 41,592 patients in the JDRS. The majority of cases (70%) were transported by the ES-DH. In the ES-DH group, age, rate of request type using key words, and rate of instrumental intervention to secure an airway were significantly greater, and the median Glasgow Coma Scale score was significantly lower than that of the other DH group. However, there was no statistically significant difference in the rate of cases with fatal outcomes between the two groups. This is the first report regarding the current status of patients with DCI transported by DH in Japan. Most patients were transported by ES-DH to the Izu Peninsula. In addition, the patients transported by ES-DH due to decompression illness tended to be severely ill; however, the outcomes of the ES-DH and other DH groups did not differ to a statistically significant extent and therefore effective recompression therapy could be successfully performed at suitable hospitals owing to timely transportation.

A Diving Accident Checklist in Izu Peninsula can be Associated with Some Pitfalls

Objective We retrospectively investigated the degree of completion of the checklist during or immediately after diving accident, who were transported by a physician-staffed helicopter emergency medical service (HEMS).

Analysis of the Activities of a Physician-Staffed Helicopter in the Coronavirus Disease 2019 Pandemic Phase

ObjectiveThe purpose of this study was to investigate changes in the duration of activity of a physician-staffed helicopter emergency medical service (HEMS) in Eastern Shizuoka Prefecture before and during the coronavirus disease 2019 pandemic. MethodsWe retrospectively investigated the duration of dispatch activities from February 2020 to June 2021 (pandemic group, n = 1,032) and from April 2016 to January 2020 (control group, n = 3,054). ResultsThere were no significant differences in the average age, percentage of male patients, interval from the request of HEMS dispatch to arrival, interval from arrival at the scene to leaving the scene, interval from leaving the scene to arrival at the hospital, or the ratio of requests for HEMS dispatch from the local fire department between the control and pandemic groups. In contrast, the interval from the first call to HEMS dispatch in the control group was significantly shorter than that in the pandemic group, and the ratio of requests for HEMS dispatch before contacting patients in the control group was significantly greater than that in the pandemic group. ConclusionThe interval from the first call to HEMS dispatch was prolonged in the COVID-19 pandemic period. However, the actual activity time of the HEMS was not affected.