Using spectral reflectance to distinguish between tracheal and oesophageal tissue: applications for airway management

Proper placement of the tracheal tube requires confirmation, and the predominant method in addition to clinical signs is the presence of end-tidal carbon dioxide. Such is the importance of confirmation that novel methods may also have a place. We previously demonstrated using ex-vivo swine tissue a unique spectral reflectance characteristic of tracheal tissue that differs from oesophageal tissue. We hypothesised that this characteristic would be present in living swine tissue and human cadavers. Reflectance spectra in the range 500-650 nm were captured using a customised fibreoptic probe, compact spectrometer and white light source from both the trachea and the oesophagus in anesthetised living swine and in human cadavers. A tracheal detection algorithm using ratio comparisons of reflectance was developed. The existence of the unique tracheal characteristic in both in-vivo swine and cadaver models was confirmed (p < 0.0001 for all comparisons between tracheal and oesophageal tissue at all target wavelengths in both species). Furthermore, our proposed tracheal detection algorithm exhibited a 100% positive predictive value in both models. This has potential utility for incorporation into airway management devices.

Medic for the millennium: the U.S. Army 91W health care specialist

The new millennium challenges the Army Medical Department to provide good care in a variety of circumstances from peacetime to operations other than war to combat. To provide care in this broad variety of missions, the Army Medical Department needs flexible providers. The new 91W health care specialist enlisted medic is designed to meet this need. By coupling skills in emergency care, evacuation, medical force protection, and primary care with certification in emergency medical technology, the 91W initiative will fill the needs of the Army now and into the new millennium.

U.S. Army MEDEVAC in the new millennium: a medical perspective

The U.S. Army Aeromedical Evacuation community (MEDEVAC) possesses a long-standing tradition of excellence in the care and transportation of combat casualties. Recent developments in civilian air medical transport and quantitative review of MEDEVAC operations have identified potential areas for improvement, concentrating on enhanced flight medic standards, training, sustainment and medical oversight of the air ambulance system. These proposed changes are discussed in detail, from the perspective of current emergency medicine and aviation medicine standards of practice. If instituted, these changes would facilitate the emergence of a true air medical transport capability comparable with the civilian community standard.

U.S. Army air ambulance operations in El Paso, Texas: a descriptive study and system review

OBJECTIVES

To analyze a high-volume military air ambulance unit and review the U.S. Army air medical transport system and Military Assistance to Safety and Traffic (MAST) program.

METHODS

The setting was a remote medical system with numerous ground emergency medical services. All patients transported between January 1, 1996, and February 28, 1998, were included. Patients who were dead on scene or for whom records were unavailable were excluded. A retrospective review of transport and available inpatient records was conducted.

RESULTS

Five hundred seventeen patients were transported during the study period; 461 patients met inclusion criteria (89%). Of these, 70% were classified as trauma; 30% possessed medical or other surgical diagnoses. Prehospital responses numbered 71.6%, while 28.4% were interhospital transfers. Missions averaged 23.4 minutes per flight, with no major aircraft mishaps. Prehospital utilization review showed appropriate use; 35% of interhospital trauma and 11% of interhospital nontrauma missions were staffed inadequately by these criteria. Time intervals, procedures, and program impact are discussed.

CONCLUSION

This and similar units participating in the MAST program provide effective air transport in settings underserved by civilian programs. Quality and wartime readiness could be improved by centralized medical direction, treatment and transfer protocols, and enhanced training of medics. Further investigations of the clinical impact of advanced training and a two-medic aircrew model are warranted.

Mass casualty triage knowledge of military medical personnel

During battlefield and mass casualty incidents, triage has been traditionally performed by many different personnel, including medics, nurses, dentists, and physicians. The objective of this study was to determine which military medical providers are most knowledgeable in mass casualty triage. The design was a prospective, written, timed, case-based examination of triage knowledge. Participants were volunteers from the active duty medical (physician), dental, nursing, and enlisted corps of the three military services. Subjects completed a 16-minute written examination consisting of seven cases in each of three simulated mass casualty scenarios: combat; nuclear, biological, and chemical; and humanitarian. Tests were taken anonymously, although demographic data on medical specialty, training, and experience were collected. Participants were instructed to classify the cases using the NATO categories of immediate, delayed, minimal, or expectant. Scores were tabulated according to two grading scales: an absolute scale of number correct, and a weighted scale amplifying gross misclassifications. Median scores between groups were tested pairwise using the Kruskal-Wallis one-way analysis of variance with p < or = 0.05. Statistically significant differences were noted between the highest and lowest scoring groups in each scenario. Our conclusion is that among the subject groups tested, physicians were best at mass casualty triage. Dentists, nurses, and medics scored progressively less well on our examination.

Army aeromedical crash rates

BACKGROUND

Safety is a principal concern for everyone in aviation, including those in military and civilian aeromedical programs. The U.S. Army flies thousands of helicopter missions each year, including many aeromedical flights. The comparison between Army general and aeromedical aviation crash data provides a benchmark for establishing patterns in aeromedical safety and may be useful for similar programs examining safety profiles.

OBJECTIVES

To determine the crash rates of Army aeromedical rotary-wing (helicopter) programs and compare them with crash rates in Army general aviation.

METHODS

Retrospective review of safety data from 1987 to 1995. Crashes or mishaps are categorized into three classes: A, B, and C. Class A reflects the most serious mishap and involves loss of life or aircraft destruction, whereas classes B and C represent lesser but still significant mishaps. Crash rates are compared on a year-by-year basis and are reported as events per 100,000 flight hours. Statistical analysis was performed by the z test with Yates' correction, with significance set at p < or = 0.05.

RESULTS

During the study period, 13.31 million total flight hours were recorded, with 741,000 aeromedical hours logged. The mean Army general aviation class A crash rate was 1.86 compared with the aeromedical rate of 2.02. The mean general class A to C crash rate was 7.37 compared with the aeromedical rate of 7.44. Between 1992 and 1995, there were 3 years when the Army aeromedical program suffered no class A mishaps. Differences between study groups are statistically significant, but they are interpreted conservatively given the very low incidence of mishaps in both groups. Both rates are comparable with published civilian mishap rates.

CONCLUSIONS

There is a very low overall incidence of crashes in both groups. There may be no practical difference between Army general and aeromedical aviation mishap rates. Furthermore, Army crash rates are comparable with published civilian mishap rates.

EMS systems: foundations for the future

Emergency medical services (EMS) occupy a unique position in the continuum of emergency health care delivery. The role of EMS personnel is expanding beyond their traditional identity as out-of-hospital care providers, to include participation and active leadership in EMS administration, education, and research. With these roles come new challenges, as well as new responsibilities. This paper was developed by the SAEM EMS Task Force and provides a discussion of these new concepts as well as recommendations for the specialty of emergency medicine to foster the continued development of all of the potentials of EMS.

Improving combat casualty care and field medicine: focus on the military medic

As military medicine in general copes with a rapidly changing world environment, so too must the backbone of the medical force, the enlisted medic. To meet these challenges, the training and utilization of military medics must match new and different missions. This paper will explore innovative approaches to training and preparing for combat casualty care and field medicine. The focus will fall on the education, evaluation, operations, patient-care skills, equipment, and telemedicine potential of the military medic. Future directions for study and development will be suggested. Exploration of the following may improve the capability of the military medic: (1) improved training to include advanced-level skills and interventions for combat casualty care and broader exposure to the casualties expected in operations other than war; (2) annual educational and periodic proficiency evaluation requirements; (3) strengthened medical control at all echelons; and (4) carefully selected additional equipment and technologies to enhance medical capabilities.

Mass gathering medicine: a review

The provision for emergency medical care for spectators and participants at large events is a growing area of interest. This article describes the definition and characteristics of medical care at mass gatherings. The literature is reviewed with regard to the planning, organization, personnel, and staffing required at these events. The equipment and transportation assets needed are also discussed. Disaster and mass casualty planning implications also are described.

Military and civilian emergency aeromedical services: common goals and different approaches

Military and civilian organizations in the U.S. operate separate but parallel emergency aeromedical services. Despite common origins, military and civilian approaches and methods have diverged. This article compares and contrasts the capabilities, priorities, safety, equipment, training and personnel of the largest military service, the U.S. Army, to civilian rotary wing (helicopter) emergency aeromedical programs. The different successes of military and civilian emergency aeromedical programs can be considered for use to improve the services of each. In general, Army programs operate larger aircraft and utilize two pilots per aircraft. Safety is a high priority and the Army aeromedical safety record is excellent. The Army also places a high degree of emphasis on crashworthiness and protective gear for the crew. Most civilian air Emergency Medical Service (EMS) programs operate small to moderate-sized aircraft flying with a single pilot. The recent safety record has improved dramatically. Civilian programs may add to their safety by considering two pilots and incorporating the crashworthy and protective advancements made by the military. Civilian programs fly with two highly trained medical technicians, nurses or physicians, equipped with state-of-the-art medical equipment. Army helicopters fly with one lesser-trained medical crewmember and less equipment. Improved combat casualty care and battlefield survival may be possible by increasing both the number and training of the medical attendants on Army aircraft.

Lessons in emergency evacuation from the Miamisburg train derailment

Hazardous materials incidents result from the release of materials considered to be harmful or potentially harmful to human beings or the environment. This article describes a train derailment and subsequent hazardous materials release with the evacuation of approximately 50,000 citizens. The hazardous materials release took five days to control and resulted in 561 patient visits to local emergency departments for symptoms related to chemical exposure. The evacuation and emergency medical operations are described and serve as a model for developing community emergency preparedness plans and managing victims involved in hazardous materials incidents.

Optimal positioning for cervical immobilization

STUDY OBJECTIVE

We hypothesized that optimal positioning of the head and neck to protect the spinal cord during cervical spine immobilization can be determined with reference to external landmarks. In this study we sought to determine the optimal position for cervical spine immobilization using magnetic resonance imaging (MRI) and to define this optimal position in a clinically reproducible fashion.

METHODS

Our subjects were 19 healthy adult volunteers (11 women, 8 men). In each, we positioned the head to produce various degrees of neck flexion and extension. This positioning was followed by quantitative MRI of the cervical spine.

RESULTS

The mean ratio of spinal canal and spinal cord cross-sectional areas was smallest at C6 but exceeded 2.0 at all levels from C2 to T1 (P < .05). At the C5 and C6 levels, the maximal area ratio was most consistently obtained with slight flexion (cervical-thoracic angle of 14 degrees) (P < .05). For a patient lying flat on a backboard, this corresponds to raising the occiput 2 cm. More extreme flexion or extension produced variable results.

CONCLUSION

In healthy adults, a slight degree of flexion equivalent to 2 cm of occiput elevation produces a favorable increase in spinal canal/spinal cord ration at levels C5 and C6, a region of frequent unstable spine injuries.

A review of spinal immobilization techniques

Immobilization of the spine is an important skill for all emergency providers. This article reviews the literature regarding the equipment, adjuncts, and techniques involved in spinal immobilization. Current prehospital practice is to apply spinal immobilization liberally in cases of suspected neck or back injury. Rigid cervical collars, long backboards, and straps remain the standard implements for immobilizing supine patients. Tape, foam blocks, and towels can complement the basic items and improve stability. Padding may improve positioning and comfort. Intermediate-stage devices include the short backboard and newer commercial devices. Properly used, all provide reasonable immobilization of the sitting patient. Future directions for study include refinement of optimal body position, dynamic performance of all devices, and broadening study populations to include children and the elderly.

On the ground at the U.S. Air Show

Careful planning and organization at mass gatherings are essential if adequate medical care is to be ensured. The U.S. Air Show in Dayton, Ohio, attracts thousands of spectators annually and requires that dozens of EMS agencies and hundreds of first responders, EMTs, paramedics, nurses and physicians join forces to provide EMS coverage.

A proposed model for a residency experience in mass gathering medicine: the United States Air Show

STUDY OBJECTIVE

Mass gathering medicine is an increasingly important responsibility for emergency physicians. A formal experience in mass gathering medicine can introduce emergency medicine residents to this aspect of community medicine.

DESIGN

Educational model based on field experience and retrospective chart review from 1981 through 1991.

SETTING

The US Air Show is a summer event that attracts an average of 223,000 spectators annually. Medical care is provided by physicians, nurses, and technicians operating within an organized system of care. Emergency medicine resident physicians (first-, second-, and third-year) evaluate and treat patients appropriate for the resident's level of responsibility. Residents provide immediate medical control and are integrated into the event disaster plan. On-site attending physician supervision is available at all times. Didactic instruction and event orientation are integrated into the residency curriculum. Residents participate in the planning stages of the event.

RESULTS

During the study period, 2,091 patients were seen. The most common presenting problems were heat illness (28%), blisters and scrapes (25%), headaches (23%), fractures and lacerations (9%), and eye injuries (5%). One hundred forty-eight patients (7%) required transportation to the hospital. Approximately 16 residents participate each year and treat an average of 13.7 patients during their four-hour shift. A resident training model for a mass gathering experience is proposed to include adequate crowd size to generate useful patient volumes; a regularly scheduled event; organized medical and disaster preparations meeting local or published standards; didactic instruction on history, principles, and current issues; on-site attending supervision; degree of responsibility appropriate for training level; participation in planning and organizing the event; and postevent debriefing.

CONCLUSION

A residency experience and training program in mass gathering medicine can introduce the principles of planning and providing care for crowds attending large public events.

Prehospital misidentification of tachydysrhythmias: a report of five cases

Identification and treatment of tachydysrhythmias is an important element of prehospital care. Five cases of prehospital misidentification of tachydysrhythmias are presented to highlight the challenges and pitfalls of field management. The literature is reviewed and discussed in light of new therapies and technology. Guidelines for patient subgroups potentially benefitting from on-line medical control and biotelemetry are explored.

Physician integration into mass gathering medical care. The United States Air Show

INTRODUCTION

Limited information exists concerning physician staffing at mass gathering events.

METHODS

A retrospective review of the preparation, planning, and provision of medical care for the United States Air Show was performed. Patient encounters from the air show for the years 1981-1991 also were evaluated.

RESULTS

The frequency rate of overall encounters was 8.45 patients/10,000 spectators and hospital transport rate was 0.6/10,000 spectators. The majority of complaints were related to heat or minor injuries. During this period, emergency physicians played a vital role in both medical planning and on-site staffing. Emergency medicine residents also participated. A small patient population received direct benefit from on-site physician intervention.

CONCLUSION

The on-site emergency physician is of benefit in event preplanning and reducing the burden on the EMS system during mass gathering events.

Retropharyngeal abscess in an afebrile child

A case of retropharyngeal abscess in a child is reported. The patient was nontoxic appearing, afebrile, and had minimal symptoms. The case is used to highlight the high index of suspicion that may be necessary to diagnose the condition. Diagnostic approaches, emergency treatment, and disposition of patients are discussed.

Lights and siren: a review of emergency vehicle warning systems

Emergency medical services providers routinely respond to emergencies using lights and siren. This practice is not without risk of collision. Audible and visual warning devices and vehicle markings are integral to efficient negotiation of traffic and reduction of collision risk. An understanding of warning system characteristics is necessary to implement appropriate guidelines for prehospital transportation systems. The pertinent literature on emergency vehicle warning systems is reviewed, with emphasis on potential health hazards associated with these techniques. Important findings inferred from the literature are 1) red flashing lights alone may not be as effective as other color combinations, 2) there are no data to support a seizure risk with strobe lights, 3) lime-yellow is probably superior to traditional emergency vehicle colors, 4) the siren is an extremely limited warning device, and 5) exposure to siren noise can cause hearing loss. Emergency physicians must ensure that emergency medical services transportation systems consider the pertinent literature on emergency vehicle warning systems.

Bilateral vocal cord hematomas associated with shoulder harness use

A case of bilateral vocal cord hematomas caused by a shoulder harness injury is presented. The patient was restrained by a three-point belt system and was involved in a front-end collision. She presented with mild facial and chest injuries and a contusion of the neck. One hour after injury she began to complain of hoarseness without airway compromise. Fiberoptic laryngoscopy showed bilateral true vocal cord hematomas. The patient had an uneventful hospital course and a full recovery. The importance of the mechanism of injury and associated injuries is discussed.

Analyzing clinical case distributions to improve an emergency medicine clerkship

Recommendations for a core curriculum for undergraduate emergency medicine education have been published. It is expected that a combination of bedside teaching and didactic sessions will cover all aspects of the curriculum, but this has not been demonstrated. This study describes a method of using the distribution of clinical cases to shape the mix of clinical and didactic learning in an emergency medicine clerkship. All senior students at the Albany Medical College participate in a four-week emergency medicine rotation. A brief log describing each clinical encounter is maintained by the students. Data from one year were sorted into 32 categories adapted from American College of Emergency Physicians guidelines and were tabulated. A criterion of 80% of students encountering at least one case in each category was chosen to ensure a reasonable level of exposure to a particular case or topic. One hundred twenty-three students were exposed to an average of 63.7 +/- 27.5 (SD) patients. Seven categories met the criterion, and the remaining 25 categories failed the criterion. Results indicate that exposure to certain categories of patients with appropriate monitoring can be reasonably ensured in our clinical setting. The didactic portion of the curriculum can be adjusted so that categories not meeting the clinical criterion will be emphasized, whereas those meeting the criterion will be de-emphasized. A method has been described that identifies gaps in the clinical exposure of students and permits appropriate identification of didactic sessions to create a clerkship more consistent with recommended guidelines.

Effect of crowd size on patient volume at a large, multipurpose, indoor stadium

A prediction of patient volume expected at "mass gatherings" is desirable in order to provide optimal on-site emergency medical care. While several methods of predicting patient loads have been suggested, a reliable technique has not been established. This study examines the frequency of medical emergencies at the Syracuse University Carrier Dome, a 50,500-seat indoor stadium. Patient volume and level of care at collegiate basketball and football games as well as rock concerts, over a 7-year period were examined and tabulated. This information was analyzed using simple regression and nonparametric statistical methods to determine level of correlation between crowd size and patient volume. These analyses demonstrated no statistically significant increase in patient volume for increasing crowd size for basketball and football events. There was a small but statistically significant increase in patient volume for increasing crowd size for concerts. A comparison of similar crowd size for each of the three events showed that patient frequency is greatest for concerts and smallest for basketball. The study suggests that crowd size alone has only a minor influence on patient volume at any given event. Structuring medical services based solely on expected crowd size and not considering other influences such as event type and duration may give poor results.