Interhospital transfer of cardiac patients: does air transport make a difference?

Introduction: The purpose of this study was to compare the outcome of interhospital transported cardiac patients for whom bias in selecting transport mode was removed due to helicopter unavailability. Methods: Patients with the diagnosis of unstable angina or myocardial infarction who underwent transport by ground only because helicopter transport was not available, were compared to patients transported by helicopter. Patients were matched by gender and referring hospital. Ninety-six patients were studied and both groups were comparable in age, diagnosis, Killip classification, treatment with thrombolytics and post-transport procedures. Results: There were no statistically significant differences between the groups for mean ICU days (5.3 air vs. 3.5 ground) and mean hospital days (9.9 vs. 8.2, respectively). No differences were detected in the proportions of deaths within 72 hours of arriving at the receiving institution (1/48 air vs. 0/48 ground), but air transportation was associated with more total deaths (9/48 vs. 1/48, respectively). Conclusion: It appears that the interhospital transport of cardiac patients by air offers no outcome advantage over ground transport.     

CT pneumoangiogram sign following cardiopulmonary resuscitation: detrimental cerebral air embolism or postmortal blood replacement with air?

Massive air in the cerebral vessels (pneumoangiogram) on postmortal computed tomography (CT) examination after cardiopulmonary resuscitation of a 10-year-old child with severe thoracic trauma is reported and possible mechanism of pneumoangiogram is discussed. The patient suffered from severe head and chest injury and was transported to hospital in a cardiopulmonary arrest state. Cardiopulmonary resuscitation was not successful and to find the cause of death, postmortal cranial CT and supine chest X-radiography were performed. Chest X-ray revealed almost total obliteration of left pulmonary aeration as well as pneumomediastinum and bilateral hydropneumothorax. On CT scans, diffuse air was seen in the carotid arteries, middle and anterior cerebral arteries, the vertebral arteries, and in the right sigmoid sinus. This pneumoangiogram sign is believed to be the end result of pumped pneumothorax–pneumomediastinum air which was sucked through the lacerated thoracic great vessels via cardiac massage, replacing the emptied cerebral vessel lumens previously depleted of blood through massive thoracic hemorrhage and has nothing to do with a death contributing detrimental cerebral air embolism.     

Is air medical scene response for illness appropriate?

The purpose of this study was to determine the appropriateness of air medical scene response for illness. The study consisted of a retrospective chart review of a two-helicopter urban air medical transport program with a transport volume of 1,700 flights annually. During the study period, January 1988 through March 1990, 68 patients were transported by helicopter from scene of illness to a tertiary care facility. In cases in which patients could be managed appropriately locally, air transport was deemed unnecessary. Of the 68 patients with illness, 40 were males and 28 were females; the average age was 39.2 years (from a range of 0 to 93). The average transport time was 46.3 minutes. Dispatch diagnoses were cardiac arrest (20), seizure (14), myocardial infarction (8), overdose (6), stroke (5), labor (4), respiratory distress (3) and miscellaneous (8). The discharge (final) diagnosis was different from dispatch diagnoses in 10 patients (14.7%). Fifty-four patients (79.4%) required no tertiary care, and 30 of them were discharged from the emergency department or were pronounced dead there or at the scene. The results of the study indicate air medical response to scene of illness did not appear justified in this study. Transport should be local, by ground, with subsequent tertiary care being arranged as needed. Further prospective study is warranted.     

When is air medical service faster than ground transportation?

The purpose of this study was to mathematically define a distance or travel-time interval in which air medical evacuation would benefit the patient more than ground transport. The authors derived mathematical formulas from known variables (ground travel, extrication and rendezvous times) and fixed averages (on-scene time, lift-off time, and speeds) and used those formulas to test actual flights for appropriateness. The formulas were: [formula: see text] where Y = ground travel time; R = rendezvous time; Z = extrication time; D = distance to scene (km); and X = air travel time. The formulas provide a guide to prospectively determine the legitimacy of air medical transport. They can also be used retrospectively as a guide for quality assurance purposes. During this study of 123 consecutive scene flights, helicopter benefitted all the entrapped patients but only one-third of non-entrapped patients. Of 44 flights from areas with known ground times, helicopter transport benefitted 14 of 16 entrapped, five of 16 non-entrapped, but only three of 17 rendezvous.     

Pilot error in air carrier accidents: does age matter?

INTRODUCTION: The relationship between pilot age and safety performance has been the subject of research and controversy since the "Age 60 Rule" became effective in 1960. This study aimed to examine age-related differences in the prevalence and patterns of pilot error in air carrier accidents. METHODS: Investigation reports from the National Transportation Safety Board for accidents involving Part 121 operations in the United States between 1983 and 2002 were reviewed to identify pilot error and other contributing factors. Accident circumstances and the presence and type of pilot error were analyzed in relation to pilot age using Chi-square tests. RESULTS: Of the 558 air carrier accidents studied, 25% resulted from turbulence, 21% from mechanical failure, 16% from taxiing events, 13% from loss of control at landing or takeoff, and 25% from other causes. Accidents involving older pilots were more likely to be caused by turbulence, whereas accidents involving younger pilots were more likely to be taxiing events. Pilot error was a contributing factor in 34%, 38%, 35%, and 34% of the accidents involving pilots ages 25-34 yr, 35-44 yr, 45-54 yr, and 55-59 yr, respectively (p = 0.87). The patterns of pilot error were similar across age groups. Overall, 26% of the pilot errors identified were inattentiveness, 22% flawed decisions, 22% mishandled aircraft kinetics, and 11% poor crew interactions. CONCLUSION: The prevalence and patterns of pilot error in air carrier accidents do not seem to change with pilot age. The lack of association between pilot age and error may be due to the "safe worker effect" resulting from the rigorous selection processes and certification standards for professional pilots.     

Trauma triage: do AAMS transport guidelines do it effectively?

PURPOSE: Appropriateness of helicopter transport for trauma patient transfer is under closer scrutiny with the development of regionalized trauma systems and managed care. This study was conducted to determine the effectiveness of the 14 Association of Air Medical Services (AAMS) guidelines in triaging trauma patients. METHODS: The application of the trauma transport guidelines for 511 patients flown to our trauma center with hospital stays of fewer than 3 days were analyzed to ensure high sensitivity to overtriage. Injury severity score (ISS), revised trauma score (RTS), Glasgow coma scale (GCS), and mortality rates associated with each of the guidelines were analyzed. RESULTS: Each guideline was associated with mortality greater than or equal to 20%, except motor vehicle, falls, amputation, and degloving. All guidelines had significant ISS (> 14), RTS (< 10), and GCS (< 12), except falls (ISS-6.7, RTS-11, GCS-13.3) and amputations (ISS-6.3, RTS-11, GCS-13.5). Degloving, motor vehicle, spinal cord, airway, and extrication also had a significantly higher RTS (> 12). CONCLUSION: The AAMS transport guidelines for trauma patients accurately predict the potential for serious or life-threatening injury, with the exception of falls and amputations. The rapid access to highly skilled reimplantation teams required by patients with amputations justifies helicopter transport. However, falls greater than 20 feet do not appear to identify potential for life-threatening injury.     

A validated pediatric transport survey: how is your team performing?

INTRODUCTION: Understanding referring practitioners' satisfaction with pediatric transport services is useful for quality improvement. Formal survey methodology was applied to develop a pediatric transport satisfaction survey. SETTING: Large metropolitan area in the Southwestern United States. METHODS: A four-stage process was used to create a 20-item pediatric transport satisfaction survey. The final survey was analyzed for test-retest and internal consistency reliability, and surveys were mailed to a large practitioner base. RESULTS: The survey encompassed three domains: patient care, accessing the transport system, and communication. Test-retest and internal consistency reliability were good (final Cronbach alpha coefficient of 0.88.) Of the 229 providers responding, 69% were local (<60 miles), and 31% were served by our long distance transport team (>60 miles). Respondents reported that physicians selected the transport team in 82% of cases, whereas 9% reported that the charge nurse decided. Transport team selection was based on: (1) ease of initiation, (2) fastest arrival, (3) presence of a physician on the team, (4) stabilization time at the referring facility, and (5) team providing best follow-up. Satisfaction with our transport service was high, with a median survey score of 83 (interquartile [IQ] range, 74-92). Physicians and nurses reported equal satisfaction. CONCLUSION: Survey design methodology was successfully applied to assess satisfaction with pediatric transport. This transport survey offers a reliable measurement of providers' satisfaction with transport services.     

Is mucociliary transport velocity related to symptoms in chronic rhinosinusitis patients?

Mucociliary transport velocity (MTV) measured by rhinoscintigraphy is considered a reliable measure of mucociliary clearance, one of the mechanisms that are distorted in chronic rhinosinusitis (CRS). The aim of this study was to investigate possible correlation of MTV with the severity of patients' symptoms. We have studied thirty-seven CRS patients who completed the 20-item sinonasal outcome test (SNOT-20) form, a reliable measure of health related quality of life and were also examined by rhinoscintigraphy with technetium-99m macroaggregated albumin. Our findings showed that the MTV of our patients ranged from nil to 4.17mm/min with a mean value of 1.74+/-1.055 mm/min. The SNOT-20 scores varied from 0.3 to 3.7 with a mean of 1.6+/-0.922. The correlation between SNOT-20 score and MTV was not statistically significant (Spearman's r=-0.191). In conclusion, although rhinoscintigraphy is widely accepted as a reliable test of mucociliary velocity and clearance, it did not correlate with subjective measures of the severity of CRS.     

What determines the periportal free air, and ligamentum teres and falciform ligament signs on CT: Can these specific air distributions be valuable predictors of gastroduodenal perforation?

Purpose

The purpose of this retrospective study was to determine what gives rise to the periportal free air, and ligamentum teres and falciform ligament signs on CT in patients with gastrointestinal (GI) tract perforation, and whether these specific air distributions can play a clinically meaningful role in the diagnosis of gastroduodenal perforation.

Material and methods

Ninety-three patients who underwent a diagnostic CT scan before laparotomy for a GI tract perforation were included. The readers assessed the presence of specific air distributions on CT (periportal free air, and ligamentum teres and falciform ligament signs). The readers also assessed the presence of strong predictors of gastroduodenal perforation (focal defects in the stomach and duodenal bulb wall, concentrated extraluminal air bubbles in close proximity to the stomach and duodenal bulb, and wall thickening at the stomach and duodenal bulb). The specific air distributions were assessed according to perforation sites, and the elapsed time and amount of free air, and then compared with the strong predictors of gastroduodenal perforation by using statistical analysis.

Results

All specific air distributions were more frequently present in patients with gastroduodenal perforation than lower GI tract perforation, but only the falciform ligament sign was statistically significant (p < 0.05). The presence of all three specific air distributions was demonstrated in only 13 (20.6%) of 63 patients with gastroduodenal perforation. Regardless of the perforation sites, the falciform ligament sign was present significantly more frequently with an increase in the amount of free air on multiple logistic regression analysis (adjusted odds ratio, 1.29; p < 0.001). The sensitivity, specificity, accuracy, and positive predictive and negative predictive values of each strong predictor for the diagnosis of gastroduodenal perforation were higher than those of specific air distributions. The focal wall thickening (accuracy, 95.7%) was the most useful parameter for the diagnosis of gastroduodenal perforation.

Conclusion

The prediction of the perforation site of the GI tract on CT should be based on the presence of strong predictors of the site of bowel perforation, and the specific free air distribution should be regarded as complementary predictors.     

MR colonography: How does air compare to water for colonic distention?

PURPOSE: To prove the feasibility of air-distended magnetic resonance colonography (MRC) and compare it with water-based distention. MATERIALS AND METHODS: In five volunteers, the colon was imaged twice: once after distending the colon with air and a second time after distending the colon with water. A total of 50 patients, who had been referred to colonoscopy for a suspected colorectal pathology were randomized into water-distention (N = 25) and air-distention (N = 25) groups. A contrast-enhanced T1-weighted three-dimensional volume interpolated breath-hold (VIBE) sequence was collected. Comparative analysis was based on qualitative ratings of image quality and bowel distention, as well as contrast-to-noise ratio (CNR) measurements for the colonic wall with respect to the colonic lumen. In addition, patient acceptance was evaluated. RESULTS: Inflammatory changes and colorectal masses were correctly identified on MRC in eight patients each. One 4-mm polyp identified at colonoscopy was missed on water-distended MRC. There were no false positive findings. No significant differences were found between air- and water-distention regarding discomfort levels and image quality. The presence of air in the colonic lumen was not associated with susceptibility artifacts. CNR of the contrast-enhanced colonic wall, as well as bowel distention, were superior on air-distended three-dimensional data sets. CONCLUSION: MRC can be performed using either water or air for colonic distention. Both techniques permit assessment of the colonic wall and identification of colorectal masses. While discomfort levels are similar for both agents, MRC with air provides higher CNR and better colonic distention.     

Effects of oxygen-enriched air on cognitive performance during SCUBA-diving – an open-water study

Backround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. Aim: Compare effects of nitrox28 and air on two psychometric tests.

Methods: In this prospective, double-blind, open-water study, 108 advanced divers (38 females) were randomized to an air or a nitrox-group for a 60-min dive to 24 m salt water. Breathing gas effects on cognitive performance were assessed during the dive using a short- and long-term memory test and a number connection test.

Results: Nitrox28 divers made fewer mistakes only on the long-term memory test (p = 0.038). Female divers remembered more items than male divers (p < 0.001). There were no significant differences in the number connection test between the groups.

Conclusion: Likely owing to the comparatively low N₂ reduction and the conservative dive, beneficial nitrox28 effects to diver performance were moderate but could contribute to diving safety.     

AMP-activated protein kinase: a critical signaling intermediary for exercise-stimulated glucose transport?

Physical exercise increases the rate of glucose transport into contracting skeletal muscles by a mechanism that involves translocation of the GLUT4 glucose transporter to the cell surface. This brief report will discuss an emerging hypothesis that suggests that the AMP-activated protein kinase is a key signaling intermediary leading to exercise-stimulated GLUT4 translocation in skeletal muscle.