Analysis of accidents during instrument approaches.

General aviation and air taxi approach phase accidents, which occurred during Visual and Instrument Flight Rules (VFR and IFR, respectively) over the last 25 years, were analyzed. The data suggest that there is a 204% higher risk during the approach and landing phase of VFR flights, than during similar IFR operations (14.82 vs. 7.27 accidents/100,000 approaches). Alarmingly, the night single pilot IFR (SPIFR) accident rate is almost 8 times the rate of day IFR, 35.43 vs. 4.47 accidents/100,000 approaches, and two and a half times that of day VFR approaches, 35.43 vs. 14.82 accidents/100,000 approaches. Surprisingly, the overall SPIFR accident rates are not much higher than dual-pilot IFR (DPIFR), 7.27 vs. 6.48 accidents/100,000 approaches. The generally static ratio of the statistics for SPIFR/DPIFR accident rates may be accounted for by little or no change in general aviation cockpit technology during the last 25 years, and because IFR operational flight task management training has not kept pace.     

Flight safety in Alaska: comparing attitudes and practices of high- and low-risk air carriers

INTRODUCTION: Aircraft operations are a vital component of the transportation system in Alaska. Between 1990-2002, a total of 481 people died in Alaska in aviation accidents. The purpose of this study was to examine the practices and attitudes of Alaska commuter and air taxi operators and their pilots as they relate to company fatal accident rates. METHODS: A case-control analysis based on accident statistics was performed, grouping operators and their pilots into cases and controls, based on operator fatal accident rates, during January 1990 to June 2001. Responses from two aviation safety surveys-one of air carrier operators and one of active commercial pilots-were compared between cases and controls. RESULTS: The average case pilot had less career flight experience than control pilots and worked 13 h x d(-1) and 81 h x wk(-10; that is, 1 h x d(-1) and 10 h wk-1 more than controls. Case operators were less likely to consider pilot fatigue a problem when scheduling flights (p = 0.05) and more likely to depend financially on timely delivery of bypass mail (p = 0.04). Case pilots were three times as likely as controls to fly daily into unknown weather conditions. Nearly 90% of case pilots reported that they never flew when so fatigued that they wanted to decline the flight, compared with 64% of control pilots (p = 0.01). CONCLUSIONS: Pilots of high-risk operators differed from those working for the other operators, both in experience and working conditions. The combination of pilot inexperience and longer work hours and workweeks may contribute to Alaska's high aviation crash rate.     

Is oral endotracheal intubation efficacy impaired in the helicopter environment?

INTRODUCTION: Patients transported by helicopter often require advanced airway management. The purpose of this study was to determine whether or not the in-flight environment of air medical transport in a BO-105 helicopter impairs the ability of flight nurses to perform oral endotracheal intubation. SETTING: The study was conducted in an MBB BO-105 helicopter. METHODS: Flight nurses performed three manikin intubations in each of the two study environments: on an emergency department stretcher and in-flight in the BO-105 helicopter. RESULTS: The mean time required for in-flight intubation (25.9 +/- 10.9 seconds) was significantly longer than the corresponding time (13.2 +/- 2.8 seconds) required for intubation in the control setting (ANOVA, F = 38.7, p < .001). All intubations performed in the control setting were placed correctly in the trachea; there were two (6.7%) esophageal intubations in the in-flight setting. The difference in appropriate endotracheal intubation between the two settings was not significant (chi 2 = 0.3; p > 0.05). CONCLUSION: Oral endotracheal intubation in the in-flight setting of the BO-105 helicopter takes approximately twice as long as intubation in a ground setting. The results support pre-flight intubation of patients who appear likely to require urgent intubation during air medical transport in the BO-105 helicopter.     

上海市车祸死亡率研究

目的：探讨车祸的现场救治．方法：对１９８１～１９９０年上海市车祸死亡率采用数学模型研究．结果：１０年中该市死亡率波动于３．６７６～６．４９１／１０万．死亡率数学模型为：ｙ＝５＋０．８３３ｓｉｎ（２ｘ／３），其平均相对误差６．８６８％，拟合优度９３．１３２％；ｙ与ｙ的相关系数０．９４５９；１９９１、１９９２年的预测精度分别为９３．３９％和９０．９５％．郊县中嘉定、宝山及青浦三地的死亡率均＞１１．２０／１０万，其中近１／２的郊县致死性车祸发生于沪青平等十三条公路上．结论：为缩短车祸后救治的反应时间，应改善郊县公路两旁的通讯设施，尽快研制适合城乡升降的直升救护机．     

Geographic variations in crash risk of general aviation and air taxis

INTRODUCTION: In the past decade, numerous studies have been published regarding the relationship of crash risk and mortality with respect to geographic area. METHODS: We analyzed data (United States only) regarding general aviation and air taxi crashes from 1992-94 from the National Transportation Safety Board. Data regarding 1993 flight hours and standard error were obtained from the Federal Aviation Administration (FAA) and pooled to provide a reliable estimate of crash risk for 1992-94. Calculations were determined for each state and FAA region. RESULTS: During the 3-yr period, the calculated United States crash rate is 8.9 crashes per 100,000 flight hours. The Alaskan and Northwest Mountain regions had the highest crash rates and fatal crash rates. DISCUSSION: This is the first study to report on geographical differences in rates determined as crashes per 100,000 pilot hours. It shows that even when the amount of flying is controlled for, crash rates and fatal crash rates are highest in mountainous regions. Our results indicate that aviation safety in mountainous regions deserves more attention.     

美国空中急救概况

美军大规模使用直升飞机转运伤员开始于朝鲜战争及后来的越南战争。根据已取得的成功经验,空中急救(air medicine)现已成为美国平时完整创伤急救系统不可分割的重要组成部分。笔者重点介绍美国空中急救的方法与经验,以供国内创伤急救医学有关人员在决策或开展中国的空中急救项目．时参考。     

A retrospective analysis of the intubations performed during 5 years of helicopter emergency medical service in Amsterdam

INTRODUCTION: Different skilled personnel perform prehospital airway management, by far one of the most challenging skills with major consequences upon failure. SETTING: The setting for this study was the helicopter emergency medical service at the Vrije Universiteit Medical Center, Amsterdam, the Netherlands. METHODS: We conducted a retrospective analysis of all medical charts of intubated trauma patients in the period from May 1995 to May 2000. We focused on intubation reasons and conditions. RESULTS: In 43 of 653 patients (7%) the process of intubation was recorded as being difficult, leading to 5 failed intubations (11.6%). In 432 of 653 trauma victims (66%), general anaesthesia was required before intubation. Forty (9%) of these patients died, most soon after arrival in the hospital. The clinical condition of 221 (34%) patients was so poor that they did not require additional drugs for intubation; 73% of those patients died, with two-thirds dying at the accident site. CONCLUSION: The rate of difficult intubation in this analysis is low (7%). The overall airway failure (11.6%) is the same as seen in the literature when sedation and relaxation are used. An adult trauma victim with a Revised Trauma Score of 0 has a very poor prognosis of survival.     

Medical considerations in the use of helicopters in mountain rescue

The outcome of patient care can be dramatically improved by bringing rapid rescue and medical care to the mountain rescue scene and by rapid transport to a medical facility. The use of a helicopter for these purposes is common. It is necessary when it has clear advantages for victims in comparison with ground rescue and transport. Helicopters should work within the existing emergency medical system and must be staffed by appropriate mountain rescue and medically trained personnel. Activation time should be as short as possible. Activation of a helicopter for a mountain rescue should primarily include indication and assessment of flight and safety conditions. No other mediators or delaying factors should be permitted. The main safety criteria are appropriate mountain rescue and flight training, competence of air and ground crews, radio communication between the air and ground crews, and mission briefing before the rescue. Criteria for a helicopter used for mountain rescue are proper medical and rescue equipment, load capacity, adequate space, and others. There are two main groups of indications for use of a helicopter for mountain rescue: the patient's condition and the circumstances at the site of the accident. All persons responsible for the activation of the helicopter rescue operation should be aware of specific problems in the mountains or wilderness.     

Feasibility of preclinical cardiac output and systemic vascular resistance in HEMS in thoracic pain--the ultrasonic cardiac output monitor

BACKGROUND: Cardiac output (CO) and systemic vascular resistance (SVR) are important hemodynamic parameters in emergency patients and for clinical early goal-directed therapy. This study evaluated the feasibility of CO and SVR determination using preclinical continuous wave Doppler ultrasound in a helicopter emergency medical service (HEMS) on emergency patients presenting with or without thoracic pain as a pilot observational study. METHODS: Forty-four consecutive medical emergency patients (62.8 +/- 22 years of age, 23 males) were classified at the scene as with (15 patients, 69 +/- 14 years of age, 40% male) or without (29 patients, 60 +/- 25 years of age, 59% male) thoracic pain by an emergency physician. Hemodynamic parameters were determined based on continuous wave Doppler noninvasively (USCOM, Sydney, Australia): stroke volume (SV), CO, cardiac index (CI), minute distance (MD), and SVR. RESULTS: Noninvasive SV, MD, CO, CI, and SVR determination is feasible using preclinical ultrasound in HEMS. Thoracic pain patients had higher SVR (2,709 +/- 891 vs 1,499 +/- 661 dyne*sec*cm-5) and lower CO/CI (3.37 +/- 1.1 vs 5.06 +/- 2.9 L/min, CI: 1.67 +/- 0.58 vs 3.18 +/- 1.34 L/min/m2) as well as a reduced aortic minute distance (11.2 +/- 3.3 m/min vs 19.1 +/- 8 m/min, P = .001) than patients without thoracic pain. Highest cardiac outputs were measured during and within 30 minutes after seizures (n = 5, 7.5 +/- 3.05 L/min). The range of CO measured in six cardiopulmonary resuscitation patients was 2.7 to 12 L/min; the level of CO was not associated with the establishing of sustained circulation. CONCLUSIONS: Determining SV, CO/CI, and SVR in different emergency situations in HEMS using rapid CW Doppler ultrasound is feasible. Thoracic pain patients have increased SVR and lower CO/CI and reduced aortic minute distance than do non-thoracic pain patients in the preclinical setting.     

Stanford Life Flight celebrates 20 years

Twenty years ago in May 1984, history was made when Stanford Life Flight became the first emergency medical services helicopter in northern California. Flight programs already existed in southern and central California when Life Flight was begun as a joint venture between Stanford and Santa Clara Valley Medical Center to cover a 250-mile service area from the San Francisco peninsula. Dr. Michael Eliastam, medical director of Stanford's emergency services at the time, had foresight in implementing paramedic service to the area during the 1970s. With the prehospital care infrastructure in place, it was time to expand the vision of advanced emergency and critical care to include air medical transport.     

Successful training of HEMS personnel in laryngeal mask airway and intubating laryngeal mask airway placement

INTRODUCTION: To evaluate laryngeal mask airway (LMA) and intubating laryngeal mask airway (ILMA) placement by helicopter emergency medical services (HEMS) personnel after a comprehensive training program. METHODS: HEMS flight staff attended a didactic and manikin-based training session for both devices. After this training, they attempted LMA and ILMA placement in live, anesthetized patients in an operating room (OR). Outcome measures included placement success rates with the LMA, ILMA, and endotracheal intubation through the ILMA, time to ventilation, and time to intubation. Success rates and time to ventilation were compared using chi-squared and analysis of variance (ANOVA), respectively. Mean time to ventilation for the first and second placements of both devices was examined with repeated measures ANOVA. RESULTS: There was no difference in successful placement of the LMA compared with the ILMA (100% vs. 91%, P = .15). Ninety-five percent (19/20) of patients were successfully intubated through the ILMA. Time to intubation was 57.1 +/- 55 seconds (range, 20-240). Mean time to ventilation with either device did not differ significantly (36.8 +/- 17 vs. 38.05 +/- 20 seconds; P = .29). Mean time to ventilation for the first and second placement of either the LMA (P = .45) or the ILMA (P = .47) was not statistically different. CONCLUSION: Trained HEMS flight staff are capable of effectively placing the LMA and ILMA in the operating room after a comprehensive training protocol.     

CT pulmonary angiography: a comparative analysis of the utilization patterns in emergency department and hospitalized patients between 1998 and 2003

OBJECTIVE: The purpose of our study was to objectively examine the temporal utilization patterns of CT pulmonary angiography in emergency department and hospitalized patients in an academic tertiary care center. SUBJECTS AND METHODS: Patients who underwent CT examination for suspected pulmonary embolism either through our emergency department or as inpatients during a recent 9-month interval were identified. The absolute number of studies and incidence of positive results and ancillary findings were compared with similar data published from our institution during the corresponding 9-month interval in 1997-1998. RESULTS: The overall number of patients imaged for pulmonary embolism was significantly greater in the 2002-2003 period than in the 1997-1998 period (homogeneity of rates = 88.45, p < 0.0001). The absolute number of scans obtained was significantly greater in both the emergency department (chi(2) = 167.03, p < 0.0001) and inpatient (chi(2) = 210.62, p < 0.0001) groups in the more recent population. Significantly fewer ancillary findings were reported in both the emergency department (chi(2) = 5.93, p = 0.019) and inpatient (chi(2) = 6.03, p = 0.015) groups in the more recent population. The incidence of CT-detected pulmonary embolism was significantly less in both the emergency department (chi(2) = 34.26, p < 0.0001) and inpatient (chi(2) = 8.52, p < 0.01) groups in the more recent population. This decrease in the incidence of scans with positive findings for pulmonary embolism over time was significantly greater in the emergency department group than the inpatient group (homogeneity of odds = 0.003, p < 0.007). CONCLUSION: The evolution of CT pulmonary angiography utilization has led to a significant increase in the number of patients being imaged for pulmonary embolism with a coincident significant decrease in the rates of CT-detected pulmonary embolism and ancillary findings both in emergency department and hospitalized patients.     

The impact of a helicopter emergency medical services program on potential morbidity and mortality

INTRODUCTION: The evaluation of the effectiveness of helicopter emergency medical services is currently a major focus of air transport research, and dispatch judgment likely will play a significant role in any research aimed at measuring outcome or impact. SETTING: Two rotor-wing programs in Alberta, Canada. METHODS: A panel of experts evaluated the effectiveness of a helicopter service in Canada. Four hundred sequential patient records were examined and categorized into four risk levels. Level 1 included patients who required critical intervention. Level 2 included patients in whom a major deterioration of vital signs could be expected. Level 3 patients were those for whom transport by an advanced life support ground unit would have been adequate. Level 4 was strictly for missions in which patient transport by any other means would have been impractical, such as remote locations (these cases were double-rated). RESULTS: Risk level 1 included 98 cases (24.5%); risk level 2, 266 cases (66.5%); risk level 3, 36 cases (9%); and risk level 4, 16 cases, two of which were rated level 1, 11 rated level 2, and three rated level 3. CONCLUSION: The results indicate that in 91% of the reviewed cases, helicopter transport was appropriate, representing a reasonable and judicious use of a helicopter emergency medical service.     

Trauma ultrasound feasibility during helicopter transport

Objective: To evaluate the feasibility of performing a standard four-view focused abdominal sonography for trauma (FAST) examination during helicopter transport using a hand-carried ultrasound machine.

Methods: In this prospective observational study, actual and simulated trauma patients were evaluated using the SonoSite 180 ultrasound machine by two air transport programs serving Level 1 trauma centers. FAST examinations were performed in flight by emergency medicine faculty, residents, flight nurses, and ultrasound technologists, who rated the difficulty posed by various factors using Likert scales (0 = not difficult to 5 = impossible). BK 117, Bell 230, and BO 105 medical helicopters flew in all aviating modes. Pilots were queried regarding avionics variations throughout the flights.

Results: Ten flight sonographers performed 21 FAST examinations on 14 patients (five actual, nine simulated). The median Likert value for each parameter was 0 except for patient position, which was 1 (somewhat difficult). Interquartile ranges were 0-0 for vibration, bedding, IV catheters, monitor cables, and ventilator; 0–0.5 for backboard straps; and 0–1 for sunlight, patient position, spider straps, gurney straps, and clothing. Mean examination duration was 3.0 minutes (range 1.5 to 5.5 minutes, SD 1.3). Pilots reported no effects on avionics in any flight mode.

Conclusion: The FAST examination using the SonoSite 180 in flight was rated by 10 evaluators to be performed easily. Examinations were conducted quickly and did not interfere with helicopter avionics. This digital ultrasound machine is the first one small enough to be used in most medical helicopters.     

Agricultural aviation medicine in the Soviet Union

The Soviet Union has developed one of the world's most sophisticated civil aviation medicine programs. The program gives specific attention to aerial application operations and includes special preflight pilot medical examinations, aircraft with specialized protective airflow systems for the pilots, minimum flight altitude spraying limit of 5 m, and the use of a "chemical log book" by each pilot in addition to the flight log book. These and additional steps--i.e. limiting a pilot's daily agricultural flights to 4-6 h--have led to a reported USSR agricultural aviation annual accident rate near zero. The Soviet workhorse aircraft, the Antonov AN-2, can serve multipurpose roles since, when not used for application flights, it can be rapidly converted to executive, courier, cargo, or air taxi, or air ambulance use. A new, single-engine turbojet biplane, the Polish M-15, is undergoing evaluation in the Soviet Union as a replacement for the AN-2. Countries with very high agricultural aircraft accident rates may wish to study the Soviet approach, especially the use by the pilot of a chemical log book.     

Sleep and cognitive performance of flight nurses after 12-hour evening versus 18-hour shifts

BACKGROUND: Inadequate rest can result in disastrous medical and aviation errors. Using a prospective within-subjects design, this study compared the amount of daily sleep and the cognitive performance in flight nurses working 12-hour evening versus 18-hour shifts during a 72-hour duty schedule. METHODS: Ten flight nurses who worked two different duty schedules participated in the study. The first duty schedule consisted of three back-to-back 12-hour (7:00 pm to 7:00 am) evening shifts. The second duty schedule consisted of two 18-hour (7:00 am to 1:00 am) shifts separated by a 24-hour rest period. Pre- and duty sleep times were monitored using actigraphy. The flight nurses were tested using a battery of neuropsychological tests before and immediately after completing 12- and 18-hour duty schedules. After the conclusion of both duty schedules, nurses were asked to rate the 12- versus 18-hour duty schedules via questionnaire. RESULTS: Daily sleep times for the 12- versus 18-hour were not different for the pre-duty schedule (8.9 +/- 2.3 vs. 9.0 +/- 2.3 hours) or during duty schedule (7.0 +/- 1.4 vs. 6.9 +/- 1.3 hours). A significant decline was seen in the amount of pre- versus duty sleep for both the 12-hour (8.9 +/- 2.3 vs. 7.0 +/- 1.4 hours; P < .05) and the 18-hour (9.0 +/- 2.3 vs. 6.9 +/- 1.3 hours; P = .04) duty schedules. During the 72-hour duty schedule, the 12-hour vs. 18-hour duty schedules, the nurses had less pre-shift sleep (3.2 +/- 1.2 vs. 6.2 +/- 0.6; P = .001) and more on-shift (4.4 +/- 1.7 vs. 2.1 +/- 0.8; P = .002) sleep. Despite the decline in daily sleep during both duty schedules, no significant decline in the before versus after cognitive test scores were observed for either the 12- or 18-hour duty schedule. A questionnaire given to the 10 nurses indicated that the 18-hour duty schedule was more compatible with their non-work lifestyle (P = .04). CONCLUSIONS: Provided adequate daily sleep (at least 7 hours/day) is obtained, we found no difference or decline in the cognitive function of flight nurses working either a 12-hour evening or 18-hour shift during a 72-hour duty schedule. Eighteen-hour duty shifts may be a practical economical means of expanding the period of helicopter site coverage without adversely affecting cognitive performance in medical crewmembers. Actigraphy may be a useful tool for air medical programs that want to objectively assess whether adequate sleep is occurring in individuals working extended (>12 hours) or unusual duty shifts.     

A comparison of pediatric and adult trauma patients transported by helicopter and ground EMS: managed-care considerations

INTRODUCTION: There is a paucity of data comparing injured pediatric patients transported by helicopter emergency medical services (HEMS) with patients transported by ground ambulance. The purpose of this study was to compare HEMS pediatric trauma patients to: 1) pediatric patients transported by ground to an urban level-1 trauma center (TC), and; 2) a similar cohort of adult patients. The managed-care consequences of these comparisons are highlighted. METHODS: All trauma patients flown directly from the scene by HEMS from January 1, 1990, to April 30, 1993, were compared to a cohort of trauma patients arriving by ground advanced life support (ALS). All patients were transported to the same level-1 TC. The data collected included the mechanism of injury and the prehospital procedures performed, the injury severity score (ISS), and outcome. RESULTS: There was no difference in the ISS between the HEMS (n = 216) and ground ALS (n = 355) pediatric patients (16.8 vs 17.1; p = 0.55). Adult HEMS patients (n = 202) had significantly higher ISS than did injured adults (n = 1652) transported by ground (18.0 vs 13.6; p < 0.0001). Overall, trauma patients transported by air directly from the scene have a higher ISS than patients transported by ground (17.5 vs 13.6; p < 0.001). CONCLUSIONS: Pediatric patients transported by HEMS were as severely injured as those transported by ground, in contrast to adult patients. We conjecture that since trauma triage schemes classically focus on adults, ground personnel are more selective about which patients are flown to a TC, and less selective for pediatric patients. Trauma centers and HEMS programs should develop pediatric trauma triage protocols that do not overemphasize physiologic parameters.     

A review of Army Air Corps helicopter accidents, 1971-1982

A comprehensive review of helicopter accident data from ACC sources is presented for the period 1971-1982. Accident and fatality rates have declined from the high values quoted in earlier studies in the 1960's and are now similar to those of fixed wing aircraft equipped with ejection seats. This improvement is related to the replacement of older reciprocating engined helicopters by turbine powered units and parallel progress in helicopter design, aircraft servicing, and pilot training. AAC accident rates now compare extremely favourably with information from civilian sources, though fatality rates are similar. Pilot error remains the main cause of accidents (75%). Particular attention is paid to subsidiary aetiologies such as tail rotor strikes, disorientation, and ground accidents. Helicopter accidents involving fatalities on Operation Corporate are mentioned briefly. Methods whereby occupant protection and aircraft crashworthiness can be improved are covered and it is concluded that assisted escape, although an ideal solution, is by no means an urgent requirement for helicopters, in view of the dramatic reduction in accident and fatality rates.