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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 21  |  Issue : 2  |  Page : 121-129

Critical care air transport team and patient transfer unit: A decade of experience of a zonal hospital


1 Department of Anaesthesiology, Command Hospital Air Force, Bengaluru, Karnataka, India
2 Department of Anaesthesiology, Army Hospital R & R, New Delhi, India
3 Department of Anaesthesiology, Hospital (SC), Pune, Maharashtra, India

Date of Submission28-May-2019
Date of Acceptance27-Aug-2019
Date of Web Publication07-Oct-2019

Correspondence Address:
Gp Capt (Dr) Parli Raghavan Ravi
Department of Anaesthesiology, Command Hospital Air Force, Bengaluru, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jmms.jmms_35_19

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  Abstract 


Introduction: The critical care air transport team (CCATT) established in 2007 a vital components of medical evacuations (MEDEVAC) in north-east India. Aim of the Study: The aim of this study was to highlight the importance of obtaining epidemiological data pertaining to the patients transported by CCATT. Method: Cases were analyzed based on the following criteria: age, sex, diagnosis of patient ,spectrum of disease and trauma, ventilation modes, inotropic support, hours of illness/injury before transport, flying time, flight distance, dedicated missions, interventions done aboard the flight and outcomes in the patient within 48 hours. Results: As many as 305 patients were analysed.39.5% patients were surgical patients, 58.5% medical and 1% was pediatric. Among surgical patients 56.8% patients were of poly trauma, 22.8% had traumatic brain injury. 68.8% of the patients transported were non-battle casualties. Dedicated missions constituted 43.4%, while the longest time for CCATT to return to base was 28 hours, shortest been 4 hours.46.8% of the patients required ventilatory support.63.4% of the patients were on inotropic support. 82.6% of the patients survived first 24 hours while 72.6 % of the patient survived 48 hours. Conclusion: Understanding the epidemiology of casualties evacuated by CCATT is an imperative requirement for the developments of effective pre-deployment training to ensure optimal outcomes for critically injured.

Keywords: Aeromedical evacuation, critical care air transport team, modified early warning scoring system, patient transfer unit, peripheral hospital


How to cite this article:
Ravi PR, Joshi M C, Dhawan M, Sud S, Vijai M N. Critical care air transport team and patient transfer unit: A decade of experience of a zonal hospital. J Mar Med Soc 2019;21:121-9

How to cite this URL:
Ravi PR, Joshi M C, Dhawan M, Sud S, Vijai M N. Critical care air transport team and patient transfer unit: A decade of experience of a zonal hospital. J Mar Med Soc [serial online] 2019 [cited 2019 Nov 14];21:121-9. Available from: http://www.marinemedicalsociety.in/text.asp?2019/21/2/121/268622




  Introduction Top


The Indian Armed Forces is expanding and rapidly changing the deployment of its resources to protect its strategic interests and fight insurgency. It is the backbone in disaster relief operations related to manmade or natural calamities. Medical support is an integral part of these operations to minimize loss of life and limb. The environment in which the Indian Armed Forces are deployed necessitates the requirement of an agile medical system that can deploy and redeploy rapidly with a reduced medical footprint. While it is possible to provide lifesaving surgical and medical support in the operation zone for the majority, a small subset of casualties will need advanced lifesaving interventions which are often time-sensitive and only available at the tertiary care centers, given the poor rail and road network and the vagaries of weather. These critically ill patients will need a MEDEVAC having enough capabilities to ensure near physiological homeostasis while being in air.[1] The capability to transport critically injured patient in the early days after injuries has altered the entire structure of the military medical system, minimizing forward deployed medical resources and allowing transfers to definitive care outside the theater of conflict. The critical care air transport team (CCATT) is a high-demand, low-density resource, designed for utilization within a full spectrum of operations, including disaster response, small-scale contingencies, homeland security, and major theaters of war.[2] Understanding the epidemiology of the casualties evacuated by CCAT is essential for developing effective predeployment training and choosing the appropriate equipment to ensure optimal outcomes for critically ill and injured warriors.[3] There is no published data with Indian in military or civil scenario, with regard to the epidemiology of MEDEVAC, elsewhere.

Two serving soldiers posted at different places in the North East with a diagnosis of pneumonia were being evacuated to a tertiary care hospital at Kolkata by a military aircraft. They were able to maintain adequate oxygen saturation on the ground but desaturated in the flight despite face mask delivered oxygen at a rate of 8 l/min. The aircraft had to make an emergency landing at Jorhat, with both the patients requiring ventilatory support for acute respiratory distress syndrome.

A 35-year-old soldier with a diagnosis of head injury was being evacuated from Chabua to Kolkata by a military aircraft, with one medical assistant as a caregiver. His preflight GCS was 15/15 which decreased to 7/15 in the flight. No facilities or expertise were available on board for securing the airway. The patient aspirated, and the aircraft had to make an emergency landing at Jorhat. The patient's airway was secured and mechanical ventilation was instituted. However, the patient could not be salvaged.

We indigenously developed a stretcher and trolley-based patient transfer unit in 2008 using local resources which housed the essential critical care equipment. Due to several structural limitations both in aircrafts and various ambulances available in armed forces, a stretcher based PTU was introduced in 2015.


  Methodology Top


Patient transfer unit

This patient transfer unit was made by modifying a hospital trolley using local resources to house the essential critical care equipment. The height of the trolley was reduced, and a special fiber material available in a local workshop was used instead of steel/wood to reduce the weight of the trolley and to bring down the center of gravity, so as to provide more stability. A special medical emergency equipment device was designed and placed at the foot of the trolley which was able to accommodate the multipara monitor, cardiac defibrillator, transport ventilator, battery-operated suction apparatus, and two infusion pumps. Two light-weighted aluminum cylinders with the ability to provide a continuous oxygen supply without interruption to the ventilator were placed at the base of the trolley. An airworthy nickle–cadmium battery connected to an inverter was fitted in the patient transport unit (PTU) to provide an additional 8 h power backup apart from the 4 h inbuilt battery backup of the equipments [Figure 1].
Figure 1: Stretcher patient transport unit

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At present, two versions of PTU are available at Jorhat – a trolley based and a stretcher based. A separate trolley (oxygen and power bank) is carried along with the trolley-based [Figure 2] or stretcher-based PTU [Figure 3] with four aluminum alloy oxygen cylinders, an AN-32 battery, inverter, and a foot-operated suction unit. The stretcher trolley-based PTU which can act as a stretcher as well as a trolley was introduced in 2010 and the stretcher only based PTU was introduced in 2015. The advantages and disadvantages are enumerated in [Table 1].
Figure 2: Stretcher trolley patient transport unit

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Figure 3: Stretcher patient transport unit

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Table 1: Advantages and disadvantages of stretcher trolley and stretcher patient transport unit

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Study design

This study is a retrospective descriptive analysis. The source of data collected is from the CCATT feedback proformas. The scientific analysis of information including that of the positive and negative feedback endorsed by the CCATT members in their postmission report has been done. Data were recorded in a specific format that included the names of referring hospital and the hospital to which the patient was transferred, date and time of the evacuation, summary and diagnosis of the case, a scoring system to define whether CCATT required or not, clinical parameters of the case – preflight, inflight and postflight, in-flight interventions performed, and the names of the team members.

Data were compiled using Microsoft excel. Descriptive statistics was calculated and compared. Means with standard deviation were calculated based on nature of data. There was an existing scoring system for evaluating the severity of casualties for deployment of the CCATT, which was a very detailed one, based on injuries and illness, with a large list of priority I and II cases. A new scoring system which was more objective and simple, based on modified early warning scoring systems (MEWS), using physiological parameters such as heart rate, systolic blood pressure (BP), respiratory rate, temperature, neurological examination, SpO2, and oxygen requirements was designed. Statistical analysis tests were performed to compare and analyze the two scoring systems to find the sensitivity and specificity of the two scoring systems and to find the degree of agreement.


  Results and Observations Top


The study involved 333 [Table 2] patients, who were air evacuated during the study period. Data were available for a total of 305 [Figure 4] patients from February 2008, involving 251 missions. Of these patients, about 75% belonged to the Indian Army, 14% to Assam Rifles, and 8% belonged to the Air Force. The transferred patients also included those belonging to territorial army (11 patients). Aeromedical evacuation (AE) of a few families (19 patients), civilians (3 patients), and one veteran too were carried out. The youngest patient evacuated was a 2-day-old neonate, the daughter of serving soldier, with a case of cyanotic congenital heart disease with transposition of great vessels, who was safely transferred from a peripheral centre to a tertiary care hospital. Mean age of the patients undergoing AE was 35.35 years (+2 standard deviation), suggesting that the majority of AEs have been undertaken for serving personnel in the younger age group who form the backbone of our fighting forces.
Table 2: Consort diagram

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Figure 4: Demography of evacuations

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A total of 251 missions were undertaken with a total flying time of 22,892 min with a mean flying time of 157 min. The details of total flying time were not available in 12 missions, and one mission was aborted as the patient's condition deteriorated before boarding the aircraft. The patient was taken back to the referring hospital.

The majority (35%) of these AEs were performed from Jorhat. A large number of AEs were from peripheral military and air force hospitals in the north-eastern sector with no advanced medical facilities available in the vicinity. Two patients of Border Roads Organization were evacuated, one from Arunanchal PRadesh and another from a civil hospital Ranchi.

Almost 90% of these patients (274) underwent AEs to Kolkata. About 4% (13) of MEDEVACS were undertaken to Jorhat using a rotary wing aircraft. Four patients underwent emergent AEs to Guwahati Medical College and Hospital, including one veteran with intractable epistaxis due to an arterial bleed within the nasal cavity which could not be controlled with conventional methods of controlling epistaxis. It was referred to an interventional radiologist at Guwahati. About four percent of patients (13/230 patients) were transferred to New Delhi as requisite facilities were not available at Kolkata, involving a transit time of about 6 h during each mission.

Out of the total number of patients air evacuated, about 59.5% (174) [Figure 5] were medical and allied cases; majority of them were transferred for management by a neurologist, i.e, 45% (78/174). The second highest transfers of medical cases were for the cardiologist –20% (35/174). About 40.5% (131/305) [Figure 6] of patients, who underwent AEs, were being transferred for surgery and allied specialties with a majority of them – 62.5% (82/131) transferred for management by a neurosurgeon followed by a GI surgeon – 9.5% (13/131). About 90.07% (118/131) [Figure 7] of patients were transferred for polytrauma after initial damage control surgeries at peripheral hospitals. Of these, the majority (61%) suffered due to road traffic accidents. About 45 patients suffered battle casualties that included gunshot wounds (30/118) and blast injuries (14/118).
Figure 5: Medical patients

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Figure 6: Surgical patients

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Figure 7: Trauma patients

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About 77% (236/305) patients were transferred on mechanical ventilator. Two patients were evacuated post tracheostomy with oxygen through a T-piece. Of these, 181 patients (76.8%) required high fraction of inspired oxygen (FiO2 > 60%), while 11 patients required a FiO2 of one. 179 (75.8%) patients required high positive end-expiratory pressure (PEEP) (≥6 cm of water), of which 89 patients required a PEEP of 10 cm of water or more [Figure 8]a and [Figure 8]b. One hundred and forty-eight patients (49%) were on vasopressor/inotropic infusions support en route [Figure 9]. Of these, 116 patients were on single vasopressor/inotropic infusion and 32 patients required two infusions to maintain the BP. Of the 305 patients, 104 patients were on mechanical ventilator as well as vasopressor/inotropic support. The majority of patients (89) received nor-adrenaline infusion to maintain the BP followed by dopamine, dobutamine, and vasopressin infusions, respectively. One patient was given intermittent boluses of ephedrine to maintain the BP en route.
Figure 8: (a) Patients requiring in-flight positive end-expiratory pressure and FIO2. (b) Patients on ventilator requiring positive end-expiratory pressure > 10 cm of water

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Figure 9: Patients on mechanical ventilations and vasopressors

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A total of 289 (94.75%) patients were given in-flight oxygen therapy [Figure 10]. These included patients on mechanical ventilator (236) and patients who received oxygen through face masks. Thirty-six patients were hypoxic (SpO2 <93%) before boarding the aircraft, of which 24 patients were on ventilator and eight patients were hypoxic on room air. One hundred and fifty-five patients were hypoxic in flight, of which about 110 patients became hypoxic about 10 min after the aircraft took off. They required an increase in PEEP and FiO2 to maintain saturations above 90%. Nine patients continued to be hypoxic even after the aircraft landed in spite of PEEP of 10 cm of water or more and a FiO2 of one. These were the sickest of all patients who posed the maximum challenge to the team in during the flight. Hence, patients who may not require oxygen on ground will require oxygen support when are being evacuated by air. Patients who are critically ill have little physiological reserve to sustain the rigors of air evacuation and will require hemodynamic as well as respiratory support for a successful evacuation.
Figure 10: Patients developing in-flight hypoxia

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Of the 236 patients who had an artificial airway in situ, 222 patients had an oral endotracheal tube while 14 patients were tracheostomized in the referring hospital for maintaining the airway before transfer was undertaken. One patient with a severe head injury with a cervical spine injury was intubated on the tarmac before boarding the aircraft as the leader of the CCAT team felt that he would not be able to sustain the rigors of air travel without a mechanical ventilator.

A total of 298 patients had a Foley's catheter in situ for monitoring of urine output and 248 patients had a nasogastric tube to facilitate feeding and decompress the stomach to avoid in-flight abdominal distension. Central venous catheters were noted to be in situ in 119 patients, and other drains were noted in 61 patients including 14 patients with intercostal drains, with under water seals for pneumo/hemothorax. Majority of patients received crystalloids - normal saline (236) or Ringer's lactate (55). Four patients received dextrose-containing fluids and 10 patients received in-flight blood transfusion.

The data acquired using each scoring system were compared with the actual requirement of CCATT based upon the recommendation of team leader of each CCATT mission and the available data of each patient. It was observed that the old scoring system showed poor agreement with a kappa coefficient of 0.162. The new scoring system based on modified early warning physiological score showed good agreement with kappa coefficient of 0.895 [Figure 10], [Figure 11] and [Table 3], [Table 4].
Figure 11: Receiver operating characteristic curve of old score with critical care air transport team requirement (gold standard)

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Table 3: Old score

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Table 4: New scoring system

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  Discussion Top


The emergency medicine services guideline 2013 dictates that patients requiring critical interventions during transport should be provided required interventions as early as possibles.[4],[5] Patients with critical injuries or illnesses resulting in unstable vital signs, who require transport by the fastest available modality, should be evacuated along with a transport team that has the appropriate level of critical care capabilities.[5],[6]

The distribution of patients having medical and surgical conditions is similar to the patient profiles being evacuated by other air transport teams throughout the world.[7] Nearly 77% of all evacuees were on ventilatory support and 49% were on continuous infusion of vasoactive drugs, necessitating the presence of an anesthesiologist in the CCATT team. In the remaining cases, the patients could have been evacuated using a scaled down PTU, with a medical officer trained in emergency medicine as a caregiver.

There is only limited data available on aeromedical evacuations of critically ill patients. Epidemiology of patients evacuated during peace is even scarcer. Data are mainly available from CCATT operations during wars like the Iraq war by Mason et al., in which the prevalence of burns patients evacuated was observed to be higher than its prevalence in other wars.[7] The largest retrospective epidemiological analysis was done by Bridges and Evers in 2009. They reported on patients evacuated during Operation Iraqi Freedom and Operation Enduring Freedom. They observed that there was a high prevalence of traumatic brain injuries, soft tissue injuries and burns in the patients evacuated during these operations.[8]

Sand et al. did a retrospective epidemiological analysis of 504 cases that underwent AE by a relief organization using an air ambulance.[9] The top three diagnoses for adults were fracture of the femoral neck (15%), stroke (14%), and myocardial infarction (14%). In our study, majority of evacuations (174/59.5%) were of medical and allied cases, of which about 78 were for management by a neurologist. Patients evacuated for surgery and allied specialties also mainly required management by a neurosurgeon (82/62.5%). In total, about 160 patients (52.4%) were evacuated for management at a neurocenter. Trauma patients constituted about 90% (118/305) of our patients. Of these, those injured in CI Ops and other counterterrorists' activities in the North-East sector constituted about 28 (9%) of the total AEs.

The new scoring system used in our study is a modification of various early warning physiological scoring systems used in various countries. These physiological early warning systems have been developed to recognize the early signs of clinical deterioration in patients admitted in hospitals so that early intervention and management can be initiated in the form of increasing nursing attention, informing the physician or activation of a rapid response team or a medical emergency team.[10],[11] Adopting an early warning physiological scoring system in a hospital setting has proven to be beneficial for standardizing the assessment of acute illness severity, enabling a more timely response using a common language across acute hospitals. A cutoff score of ≥6 out of a total score of 21 means that the patient is sick enough to warrant intensive monitoring and treatment in-flight by the CCAT team (urgent or emergent AE). A score of 3–5 means that the patient is stable but requires monitoring more than what is considered for elective AE. A score of 0–2 means the patient is stable and unlikely to deteriorate in flight due to the patient's condition or rigor of aeromedical evacuation (elective AE). Similar score of Modified Early Warning Score (MEWS) is used by the intensive care Society of UK for the transport of critically ill adults.[10],[11]

By analyzing the two scoring systems used in the study, it has been observed that the old scoring system is not only a very detailed one with a long list of priority I and II cases but also has a sensitivity of 16% and a specificity of 100%, at a cutoff of 12/20 with Kappa coefficient of 0.162. This indicates poor agreement with AUC 0.934 (0.904–0.965), when compared with the need for activation of CCATT, as per CCATT leader recommendations, as well as based on the available data. At a cutoff value of 5/20, the sensitivity improves to 86%, but specificity becomes 80% [Figure 11].

The new scoring system fares better at a cutoff of 6/21, the sensitivity is 97%, and specificity is 92% with an AUC of 0.969 (0.943–0.995). The Kappa coefficient is 0.895, indicating good agreement when compared with the need for activation of CCATT as per CCATT leader recommendations as well as based on the available data [Figure 12]. Further studies will be required to validate our findings in this study.
Figure 12: Receiver operating characteristic curve of new score with critical care air transport team requirement (gold standard)

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The CCATT comprised of one anesthesiologist, one operation room assistant (ORA), one nursing officer, two medical assistants (or Ab initio trainee medical assistants), and one house keeper, all detailed on a rotational basis from their respective pools. Medical assistants contribution to in-flight care is negligible, and very often, they suffer from airsickness as they have no prior experience of travelling in an aircraft. The anesthesiologist, ORA, and nursing officer have no formal training in AE. The CCATT needs to be well versed with critical care monitoring and procedures and at the same time possesses sufficient knowledge of aviation medicine, particularly the effect of the flight environment on patient physiology and homeostasis, which is very often delicately balanced in the critically ill.

Suitable basic and advanced learning capsules need to be formulated and implemented in the various service courses which medical officers of the armed forces undergo. The USAF has a 2 weeks' intensive course to provide critical care professionals with an introduction to aerospace physiology and the clinical and operational requirements of critical care transport. This is followed by an ongoing sustainment training program including participation in exercises.[12]

Prior information from the treating doctor about the current condition of the patient as well as details of drug therapy were available to the CCATT team, in <5% of the cases. This put the CCATT at a disadvantage as successful MEDEVAC of the critically ill hinges on meticulous preflight preparation of the patient. In sharp contrast, the air forces of the western world ensure that all patient details are available with the evacuating team as rapidly as possible.[13] A serving soldier, a gun shot victim with a small unilateral pneumothorax at Dimapur. The doctor did not put in a chest tube, as he thought that it would resolve spontaneously. However, he was unaware that the volume of trapped air could increase by 35% from sea level to 8000 ft, which is the cabin altitude of military aircraft.[5] The CCATT team leader after reaching Dimapur had to ensure that a chest tube was placed, which led to an avoidable delay. Similarly, 24 cases of 236 who received ventilatory support did not have a compromised airway and were having adequate gas exchange indices on ground; however, they could have lost their airway or could have had a problem with gas exchange in the air. Therefore, they were given prophylactic airway protection and ventilation before the MEDEVAC, which again led to an unnecessary delay. These cases highlight the importance of having detailed information about the patient's condition and knowledge of aviation medicine.


  Conclusions Top


The PTU is an essential and vital step forward in the safe and speedy evacuation of casualties from remote geographical areas. The capability of onboard monitoring, cardiorespiratory support, and intervention has permitted the movement of casualties which could not be transported in earlier years, resulting in more lives and limbs being saved.

Our experiences with MEDEVAC of critically ill patients show that >75% of the cases were from units located further east of Jorhat/Guwahati. The flying time from these units to Jorhat or Guwahati by rotary wing A/C is about 2–3 h. To ensure a smooth and speedy transfer, all peripheral hospitals where facility of a surgical team exists should have a light weight PTU with equipment powered by hot swappable nickel–cadmium batteries. These patients can then be evacuated to the nearby zonal hospitals by rotary wing aircraft from where the CCATT should take over and further evacuate the patient to a tertiary care center. Presently in IAF there are a PTU in about 10 station medicare centers close to military airbases.

The experience gained over the years can be utilized to overcome the limitations and short comings encountered and enhance professional and administrative capabilities of the CCATT. The objective would be to ensure that all casualties can be safely transported to the appropriate tertiary care facilities. More such teams and PTU need to be placed at peripheral and zonal hospitals to ensure comprehensive combat medical support to the Indian Armed Forces.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Pierce PF, Evers KG. Global presence: USAF aeromedical evacuation and critical care air transport. Crit Care Nurs Clin North Am 2003;15:221-31.  Back to cited text no. 1
    
2.
Transporting your Patient Guidelines for Organizing and Preparing Patients for Transfer by Air; Royal Flying Doctor Service of Australia Western Operations. Version: 1.7; 2013.  Back to cited text no. 2
    
3.
Air Mobility Command. Pamphlet 11–303. Access to the Aeromedical Evacuation System. Washington, DC: Department of the Air Force; 2014.  Back to cited text no. 3
    
4.
U.S. Air Force. Instruction 41–307. Aeromedical Evacuation Patient Considerations and Standards of Care. Washington, DC: Department of the Air Force; 2014.  Back to cited text no. 4
    
5.
Essebag V, Halabi AR, Churchill-Smith M, Lutchmedial S. Air medical transport of cardiac patients. Chest 2003;124:1937-45.  Back to cited text no. 5
    
6.
Roedig E. Aeromedical Evacuation. Brig. Gen. Ret. MD, CFS; RTO-MP-HFM-157-06; 2014.  Back to cited text no. 6
    
7.
Mason PE, Eadie JS, Holder AD. Prospective observational study of United States (US) air force critical care air transport team operations in Iraq. J Emerg Med 2011;41:8-13.  Back to cited text no. 7
    
8.
Bridges E, Evers K. Wartime critical care air transport. Mil Med 2009;174:370-5.  Back to cited text no. 8
    
9.
Sand M, Bollenbach M, Sand D, Lotz H, Thrandorf C, Cirkel C, et al. Epidemiology of aeromedical evacuation: An analysis of 504 cases. J Travel Med 2010;17:405-9.  Back to cited text no. 9
    
10.
The Intensive Care Society. Guidelines for the Transport of the Critically Ill Adult. 5th ed. UK: The Intensive Care Society; 2017.  Back to cited text no. 10
    
11.
Beth Smith ME, Jorgan WV. Early Warning System Scores: A Systematic Review. Washington, DC: Department of Veterans Affairs, Health Services Research & Development Service; 2014.  Back to cited text no. 11
    
12.
Rice DH, Kotti G, Beninati W. Clinical review: Critical care transport and austere critical care. Crit Care 2008;12:207.  Back to cited text no. 12
    
13.
Galvagno SM, Dubose JJ, Grissom TE, Fang R, Smith R, Bebarta VS, et al. The epidemiology of critical care air transport team operations in contemporary warfare. Mil Med 2014;179:612-8.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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