Rhabdomyolysis, Methamphetamine, Amphetamine and MDMA Use: Associated Factors and Risks.

OBJECTIVE: Rhabdomyolysis is associated with methamphetamine, amphetamine, and methylenedioxymethamphetamine (MA) use. The aim of this study was to determine the frequency, severity, and risk factors of rhabdomyolysis associated with MA use. Methods: We reviewed patients with an MA-positive toxicology screen with and without diagnosed rhabdomyolysis based on initial creatine kinase (CK) concentration over a period of 6 years. Demographics, vital signs, disposition, diagnoses, and laboratory results were recorded. Results: There were 7,319 patients with an MA-positive toxicology screen, of whom 957 (13%) were screened for rhabdomyolysis and included in the study. The majority were male, White, and middle-aged and smoked tobacco. Psychiatric (34%), neurological (15%), and trauma (13%) were the most common discharge diagnostic groups. The majority (55%) were admitted, and 8% were discharged to an inpatient psychiatric facility. Concomitant substance use included ethanol (10%) and cocaine (8%), and 190 (20%) had rhabdomyolysis with median (interquartile range) CK of 2,610 (1,530-6,212) U/L and range 1,020 to 98,172 U/L. There was significant difference in renal function between the rhabdomyolysis and non-rhabdomyolysis patients. Other differences included gender and troponin I concentration. A higher proportion of patients screening positive for both MA and cocaine use experienced rhabdomyolysis. Multiple logistic regression analysis revealed elevated troponin I, blood urea nitrogen, and/or creatinine concentration and male gender to be significant factors associated with rhabdomyolysis. Conclusions: The frequency of rhabdomyolysis in patients screening positive for MA was 20%. Factors associated with rhabdomyolysis in MA-positive patients included elevated troponin, blood urea nitrogen, creatinine concentration, and male gender. Clinicians caring for patients who screen positive for MA should also consider concomitant rhabdomyolysis, especially if renal/cardiac laboratory tests are abnormal and even if there is no history of injury, agitation, or physical restraint.

Altitude decompression sickness incidence among U-2 pilots: 1994-2010.

INTRODUCTION: The U-2 aircraft exposes its pilots to cabin pressures equivalent to 29,500 ft (8992 m) during flight, placing them at risk for decompression sickness (DCS). Historical data documenting DCS in the U-2 pilot community is lacking. This study assesses how rates and types of DCS have changed temporally in the U-2 flight program. METHODS: We created a database of all DCS cases among U-2 pilots from 1994 through 2010. Cases were analyzed by date of occurrence and symptoms experienced. Flight data were collected to calculate DCS incidence rates. RESULTS: From 1994-2010, there were 73 documented DCS cases in U-2 pilots. Between 1994 and 2005, the number of annual cases ranged from 0-5; between 2006 and 2010, the number of annual cases increased to 6-10. Additionally, there was a trend toward more severe (neurologic and pulmonary) cases between 2006 and 2010 with 22 cases compared to 10 cases the preceding 12 yr. The most common presentations of U-2 DCS were joint pain (59%), mainly involving large joints, and generalized neurologic symptoms (44%). From 2006-2010, there was an increase in the average annual flight hours per pilot to meet wartime operational needs that correlated temporally with the increase in number and severity of DCS cases. The DCS risk per flight was 0.076% from 1994-2005 but increased to 0.23% from 2006-2010. CONCLUSIONS: DCS remains prevalent among U-2 pilots. An increase in number and severity of cases correlated temporally with increased operational tempo of the U-2 squadron. Changes in cockpit pressurization and limiting the length and frequency of hypobaric exposure may reduce future incidence.

In-flight urine collection device: efficacy, maintenance, and complications in U-2 pilots.

INTRODUCTION: Urine collection systems for in-flight use have gradually improved over the past 50 yr; however, current management of urine evacuation remains suboptimal. This is a cross-sectional survey-based study on the current urine collection device employed in the U.S. Air Force's U-2S airframe, examining efficacy, problems with wear, device maintenance, and complaint reporting. METHODS: An anonymous survey consisting of 18 questions was generated inquiring about problems with wear of the urine collection system, care of the device, and education. The survey was offered at Beale AFB and overseas U-2 locations to pilots with at least 180 h of flying experience with the airframe. RESULTS: There were 57 subjects who completed the survey with 62.5% reporting complications, including mechanical dysfunction, pain and poor fit, skin irritation, allergic reaction, embarrassment, and urethral issues. Variation was seen in the degree of problem reporting and care of the device. Discussion and literature review is provided on in-flight and space urine collection and evacuation systems, sheath catheters, urine and contact dermatitis, urethritis, external catheter sizing methods, and psychological aspects of catheter use. CONCLUSIONS: The majority of surveyed pilots experienced various problems associated with wear of their urine collection device. Also, variation in reporting and care of the device exists. Potential improvements include standardization of fitting procedures and device maintenance, increased catheter draining capacity, use of skin barriers to urine, enhanced privacy measures, and incorporation of less injurious structural materials such as silicone.

Neurological altitude decompression sickness among U-2 pilots: 2002-2009.

INTRODUCTION: Compared to the previous 47 yr, U-2 pilots reported an increased number of altitude decompression sickness (DCS) incidents with central nervous system (CNS) manifestations during 2002-2009. Due to increasing incident severity during military operations, the U.S. Air Force initiated an investigation to prevent future mishaps. METHODS: We retrospectively examined all neurological DCS cases observed among U-2 pilots during 2002-2009. Urgency to prevent further pilot losses limited this study to using existing, often incomplete data sources. RESULTS: During 2002-2009, 16 confirmed incidents of CNS DCS occurred with 13 pilots, plus 4 possible incidents with 4 pilots. Significantly, 12 of 16 confirmed incidents occurred at 1 operating location, including 4 of 5 life-threatening cases. This series of cases were of a type and severity rarely found in flight operations and correlated temporally with increased sortie frequency/duration associated with combat operations. Multiple investigations confirmed no defects in aircraft, support equipment, or oxygen supplies. Nor were significant trends observed with age, habitus, environmental exposure, medication use, or cardiac defects. In 11 cases, symptom recognition occurred well after the 4-h point where clinical experience indicated risk should stabilize. Symptoms also recurred days later and responded to repeat hyperbaric oxygen therapy in three of four cases. Finally, neuropsychiatric symptoms persisted in six pilots for years and may represent permanent injury. CONCLUSIONS: An increase in U-2 CNS DCS cases probably resulted from more cockpit activity combined with longer, more frequent high-altitude exposures. Adjustments in preoxygenation, cabin altitude, exercise at altitude, and frequency of flights may reduce incidence.

The effect of vein repair on the risk of venous thromboembolic events: a review of more than 100 traumatic military venous injuries.

BACKGROUND: The management of venous trauma remains controversial. Critics of venous repair have cited an increased incidence of associated venous thromboembolic events with this management. We analyzed the current treatment of wartime venous injuries in United States military personnel in an effort to answer this question. METHODS: From December 1, 2001, to October 31, 2005, all United States casualties with named venous injuries were evaluated. A retrospective review of a clinical database was performed on demographics, mechanism of injury, associated injuries, treatment, outcomes, and venous thromboembolic events. Data were analyzed using the Fisher exact test, analysis of variance, and logarithmic transformation. RESULTS: During this 5-year period, 82 patients sustained 103 named venous injuries due to combat operations. All patients were male, with an average age of 27.9 years (range, 20.3-58.3 years). Blast injuries accounted for 54 venous injuries (65.9%), gunshot wounds for 25 (30.5%), and motor vehicle accidents for 3 (3.6%). The venous injury was isolated in 28 patients (34.1%), and 16 (19.5%) had multiple venous injuries. The venous injury in two patients was associated with acute phlegmasia, with fractures in 33 (40.2%), and 22 (28.1%) sustained neurologic deficits. Venous injuries were treated by ligation in 65 patients (63.1%) and by open surgical repair in 38 (36.9%). Postoperative extremity edema occurred in all patients irrespective of method of management. Thrombosis after venous repair occurred in six of the 38 cases (15.8%). Pulmonary emboli developed in three patients, one after open repair and two after ligation (P > .99). CONCLUSION: In the largest review of military venous trauma in more than three decades, we found no difference in the incidence of venous thromboembolic complications between venous injuries managed by open repair vs ligation. Blast injuries of the extremities have caused most of the venous injuries. Ligation is the most common modality of treatment in combat zones. Long-term morbidity associated with venous injuries and their management will be assessed in future follow-up studies.