Aeromedical Transport of Critically Ill Patients: A Literature Review

Emergency critical care: closing the gap between onset of critical illness and intensive care unit admission

Critical illness is an exquisitely time-sensitive condition and follows a disease continuum, which always starts before admission to the intensive care unit (ICU), in the majority of cases even before hospital admission. Reflecting the common practice in many healthcare systems that critical care is mainly provided in the confined areas of an ICU, any delay in ICU admission of critically ill patients is associated with increased morbidity and mortality. However, if appropriate critical care interventions are provided before ICU admission, this association is not observed. Emergency critical care refers to critical care provided outside of the ICU. It encompasses the delivery of critical care interventions to and monitoring of patients at the place and time closest to the onset of critical illness as well as during transfer to the ICU. Thus, emergency critical care covers the most time-sensitive phase of critical illness and constitutes one missing link in the chain of survival of the critically ill patient. Emergency critical care is delivered whenever and wherever critical illness occurs such as in the pre-hospital setting, before and during inter-hospital transfers of critically ill patients, in the emergency department, in the operating theatres, and on hospital wards. By closing the management gap between onset of critical illness and ICU admission, emergency critical care improves patient safety and can avoid early deaths, reverse mild-to-moderate critical illness, avoid ICU admission, attenuate the severity of organ dysfunction, shorten ICU length of stay, and reduce short- and long-term mortality of critically ill patients. Future research is needed to identify effective models to implement emergency critical care systems in different healthcare systems.

Safety of helicopter transport in patients with acute coronary syndrome

BACKGROUND

ST-elevation myocardial infarction (STEMI) systems of care have reduced inter-hospital transfer times and facilitated timely reperfusion goals. Helicopters may be an option when land transportation is not feasible; however, the safety of air transport in patients with acute coronary syndrome (ACS) is a factor to consider.

OBJETIVES

The aim of this study was to evaluate the safety of helicopter transport for patients with ACS.

METHODS

Prospective, observational, and descriptive study including patients diagnosed with ACS within the STEMI network of a metropolitan city transferred by helicopter to a large cardiovascular center to undergo percutaneous coronary intervention. The primary outcome of the study was the incidence of air-travel-related complications defined as IV dislodgement, hypoxia, arrhythmia, angina, anxiety, bleeding, and hypothermia. Secondary outcomes included the individual components of the primary outcome.

RESULTS

A total of 106 patients were included in the study; the mean age was 54 years and 84.9% were male. The most frequent diagnosis was STEMI after successful fibrinolysis (51.8%), followed by STEMI with failed fibrinolysis (23.7%) and non-reperfused STEMI (9.4%). Five patients (4.7%) developed at least one complication: IV dislodgement (1.8%) and hypoxemia (1.8%) in two patients and an episode of angina during flight (0.9%). A flight altitude of > 10,000 ft was not associated with complications.

CONCLUSIONS

The results of this study suggest that helicopter transportation is safe in patients undergoing acute coronary syndrome, despite the altitude of a metropolitan area.

Effectiveness of Negative Pressure Wound Therapy During Aeromedical Evacuation Following Soft Tissue Injury and Infection

INTRODUCTION

Negative pressure wound therapy (NPWT) is utilized early after soft tissue injury to promote tissue granulation and wound contraction. Early post-injury transfers via aeromedical evacuation (AE) to definitive care centers may actually induce wound bacterial proliferation. However, the effectiveness of NPWT or instillation NPWT in limiting bacterial proliferation during post-injury AE has not been studied. We hypothesized that instillation NPWT during simulated AE would decrease bacterial colonization within simple and complex soft tissue wounds.

METHODS

The porcine models were anesthetized before any experiments. For the simple tissue wound model, two 4-cm dorsal wounds were created in 34.9 ± 0.6 kg pigs and were inoculated with Acinetobacter baumannii (AB) or Staphylococcus aureus 24 hours before a 4-hour simulated AE or ground control. During AE, animals were randomized to one of the five groups: wet-to-dry (WTD) dressing, NPWT, instillation NPWT with normal saline (NS-NPWT), instillation NPWT with Normosol-R® (NM-NPWT), and RX-4-NPWT with the RX-4 system. For the complex musculoskeletal wound, hind-limb wounds in the skin, subcutaneous tissue, peroneus tertius muscle, and tibia were created and inoculated with AB 24 hours before simulated AE with WTD or RX-4-NPWT dressings. Blood samples were collected at baseline, pre-flight, and 72 hours post-flight for inflammatory cytokines interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor alpha. Wound biopsies were obtained at 24 hours and 72 hours post-flight, and the bacteria were quantified. Vital signs were measured continuously during simulated AE and at each wound reassessment.

RESULTS

No significant differences in hemodynamics or serum cytokines were noted between ground or simulated flight groups or over time in either wound model. Simulated AE alone did not affect bacterial proliferation compared to ground controls. The simple tissue wound arm demonstrated a significant decrease in Staphylococcus aureus and AB colony-forming units at 72 hours after simulated AE using RX-4-NPWT. NS-NPWT during AE more effectively prevented bacterial proliferation than the WTD dressing. There was no difference in colony-forming units among the various treatment groups at the ground level.

CONCLUSION

The hypoxic, hypobaric environment of AE did not independently affect the bacterial growth after simple tissue wound or complex musculoskeletal wound. RX-4-NPWT provided the most effective bacterial reduction following simulated AE, followed by NS-NPWT. Future research will be necessary to determine ideal instillation fluids, negative pressure settings, and dressing change frequency before and during AE.

Helicopter Ambulance Transport to the Emergency Department: Demographic and Clinical Factors Impacting Outcomes in a Turkish Medical Center

BACKGROUND Helicopter ambulances (HAs) are a significant component of pre-hospital emergency medical services. This study presents a report on the demographic and clinical factors associated with transport to the emergency department (ED) by HA of 161 patients to a single center in Turkey. MATERIAL AND METHODS Demographic data, diagnoses in arriving center's ED, transferred distance, and outcomes of 161 patients transferred by HAs between March 01, 2019 and May 31, 2021 were retrospectively evaluated. Mortality rates of the cases were compared both with age and according to the distance traveled within the diagnostic groups. RESULTS There were 134 patients (83.2%) with internal diseases, and cardiovascular diseases were the leading cause (68 patients, 41.6%); 27 patients (16.7%) were transferred due to trauma. The mean distance traveled with HAs was 167.1 km (range, 47.0-1316.0) and the median transfer time was 50 min. The most common form of hospitalization after ED arrival was intensive care hospitalization (n=78, 48.4%). Mortality increased as the transfer distance increased in elderly patients, as well as those with a cardiac or trauma-related diagnosis (P=0.015, P=0.044, P=0.028, respectively). CONCLUSIONS Most patients transferred by HA had severe disease. ED physicians dealing with patient transfer by HAs should be prepared for severe cases, both in the HA and in the ED. HAs may be preferred when making the transfer decision for elderly patients, trauma patients, and those with cardiac disease.

Aeromedical retrieval services characteristics globally: a scoping review

BACKGROUND

Aeromedical emergency retrieval services play an important role in supporting patients with critical and often life-threatening clinical conditions. Aeromedical retrieval services help to provide fast access to definitive care for critically ill patients in under-served regions. Typically, fixed-wing aeromedical retrieval becomes the most viable transport option compared with rotary-wing aircraft when distances away from centres of definitive care extend beyond 200 kms. To our knowledge, there are no studies that have investigated fixed-wing aeromedical services in the member countries of the organisation for economic cooperation and development (OECD). A description of the global characteristics of aeromedical services will inform international collaboration to optimise clinical outcomes for patients.

AIM

In this scoping review, we aimed to describe the features of government- and not-for-profit organisation-owned fixed-wing aeromedical retrieval services in some of the member countries of the OECD.

METHODS

We followed scoping review methodology based on the grey literature search strategy identified in earlier studies. This mostly involved internet-based searches of the websites of fixed-wing aeromedical emergency retrieval services affiliated with the OECD member countries.

RESULTS

We identified 460 potentially relevant records after searching Google Scholar (n = 24) and Google search engines (n = 436). After removing ineligible and duplicate information, this scoping review identified 86 government-and not-for-profit-operated fixed-wing aeromedical retrieval services as existing in 17 OECD countries. Concentrations of the services were greatest in the USA followed by Australia, Canada, and the UK. The most prevalent business models used across the identified OECD member countries comprised the government, not-for-profit, and hybrid models. Three-quarters of the not-for-profit and two-fifths of the hybrid business models were in the USA compared to other countries studied. The government or state-funded business model was most common in Australia (11/24, 46%), Canada (4/24, 17%), and the UK (4/24, 17%). The frequently used service delivery models adopted for patients of all ages included primary/secondary retrievals, secondary retrievals only, and service specialisation models. Of these service models, primary/secondary retrieval involving the transportation of adults and children from community clinics and primary health care facilities to centres of definitive care comprised the core tasks performed by most of the aeromedical retrieval services studied. The service specialisation model provided an extra layer of specialist health care dedicated to the transportation of neonates and paediatrics. At least eight aeromedical retrieval services catered solely for children from birth to 16 years of age. One aeromedical service, the royal flying doctor service in Australia also provided primary health care and telehealth services in addition to primary retrieval and interhospital transfer of patients. The doctor and registered nurse/paramedic (Franco-German model) and the nurse and/or paramedic (Anglo-American model) configurations were the most common staffing models used across the aeromedical services studied.

CONCLUSIONS

The development and composition of fixed-wing aeromedical emergency retrieval services operated by not-for-profit organisations and governments in the OECD countries showed diversity in terms of governance arrangements, services provided, and staffing models used. We do not fully understand the impact of these differences on the quality of service provision, including equitable service access, highlighting a need for further research.

Vehicle Dynamics Endured by Patients during Emergency Evacuation—Ambulance versus Helicopter

In the event of a road accident, a quick intervention is crucial. The mobile emergency services take care of patients whose condition requires an emergency repatriation to a hospital, by land in an ambulance or by air in a helicopter. The main criteria for choosing the means of transport are the time required for repatriation and the patient’s more or less critical state of health. Do the vehicle dynamic effects endured by the transported patient have an influence on their health condition? Vehicle dynamics data were recorded with a road data recorder for a period of 3 months, under real conditions of patient repatriation to a hospital; 39 trips were recorded by ambulance and 29 trips by helicopter. Significant differences in speed (average 42 versus 202 km/h) and distance travelled (average 23 versus 85 km) were observed. The sustained effects are similar in helicopters and ambulances. The ambulance causes more abrupt variations in longitudinal and transversal directions, whereas the helicopter has more variations in vertical direction. The vibration level in helicopters is higher than in ambulances. These results can be considered as a first reference baseline for establishing a characterization of transported patients’ exposure to vehicle dynamics.