Aviation, space, and environmental medicine最新文献

Background: The aim of this study was to assess the distribution and dynamics of temperature changes on the surface of selected body parts after systemic cryostimulation. The changes that occurred as a reaction to the 1st, 5th, and 10th session of a series of 10 sessions were also analyzed.

Methods: The study group consisted of 24 students (12 women and 12 men, ∼21 yr of age) from the University School of Physical Education in Krakow. They were treated in a cryogenic chamber at the Rehabilitation Center in Krakow once daily for 10 d. The mean temperature in the chamber was -130°C ± 10°C and the session duration was 3 min. Thermovisual examination of temperature distribution in the selected parts of the upper and lower extremities was conducted before and immediately after a session on the 1(st) (S1), 5(th) (S2), and 10(th) (S3) day of treatment. All thermograms were digitally recorded using a Flir Therma CAM TM Sc500 camera.

Results: On the 5th day of treatment, the examined group demonstrated the smallest mean temperature changes (4.57°C-17.31°C for the anterior part of the upper extremities in men and the posterior part of the lower extremities in women, respectively) before and after cryostimulation. The most significant temperature changes were observed in the group of women (6.80°C-20.08°C for the posterior parts of the upper extremities on S2 and the lower extremities on S3, respectively).

Conclusion: There is an important difference in response to cryogenic temperature between men and women in a series.

Background: Respiratory sinus arrhythmia (RSA) is characterized by normal fluctuations in heart rate in phase with the respiratory cycle. There are many proposed mechanisms underlying the RSA phenomenon, including respiratory-induced cardiac loading (i.e., Bainbridge reflex), arterial baroreflex activation, vagal feedback from pulmonary stretch receptors, and central neural mechanisms. It is currently unclear to what extent these mechanisms are responsible for eliciting RSA in humans, particularly in response to stressors.

Case report: Here we present a case report of a healthy 26-yr-old woman (BMI 22.95 kg · m(-2)) who developed extreme RSA when exposed to the simultaneous cardiac loading stressors of 45° head-down tilt (HDT) and increased tidal volume during CO2 rebreathing. During baseline breathing in both supine and 45° HDT position, RSA magnitude was similar (mean ∼10-14 bpm). RSA was tidal volume-dependent, whereby in the supine position the RSA magnitude doubled with an approximate doubling in tidal volume during rebreathing (mean ∼20 bpm). However, when HDT and rebreathing were superimposed, extreme RSA was elicited (mean ∼45 bpm; range ∼38-110 bpm), approximately 450% over baseline breathing in the supine position. ECG analysis and follow up medical assessment revealed no underlying cardiac pathology.

Discussion: The existence of extreme RSA when HDT and increased inspired volumes were superimposed suggests that the dual cardiac loading stimuli acted synergistically, increasing RSA magnitude over either stimulus alone. This case report may be relevant to situations where orthostatic stress and augmented tidal volumes are superimposed, or more generally when conflicting sympathetic and parasympathetic activation is simultaneous.

Objective: This study aimed to elucidate the overall risk and demographic/occupational predictors of neck pain among professional aviators.

Methods: There were 413 surveys characterizing the severity and character of neck pain symptoms that were administered to a multinational cohort of pilots representing 3 separate airframe types. All results were compared to a nonaviator control group. Univariate and multivariate regression analyses were performed to elucidate independent predictors of occupationally related neck pain.

Results: Of the surveys, 92% were completed and returned. Multivariate analysis reveals that the pilot profession is independently predictive of increased occupational neck pain symptoms (OR 1.94, 95% CI 3.72, 1.01). High performance airframes, cargo/passenger airframes, and increasing age were also independent predictors of increased neck pain scores (OR = 3.91, 95% CI 7.10, 2.15; OR = 3.22, 95% CI 5.83, 1.77; OR = 4.00, 95% CI 7.43, 2.15, respectively).

Conclusions: Our broad, multinational/multi-airframe analysis reveals that the pilot profession, most notably high performance and long-haul cargo/passenger airframes, display an increased risk of neck pain symptoms.

Lumbar puncture (LP) is a commonly performed low-risk procedure terrestrially, used diagnostically for evaluation of cerebrospinal fluid (CSF) pressure as well as for collection of CSF for analysis. NASA is investigating noninvasive means for measurement of intracranial pressure (ICP) to assess the potential contribution of elevated intracranial pressures to recently reported changes in astronauts' visual acuity and eye anatomy, known collectively as the Visual Impairment/Intracranial Pressure risk. However, many of these noninvasive technologies are still under development, have limited clinical validation, are several years away from being ready for in-flight use, or only provide qualitative rather than quantitative ICP values. Therefore, performance of in-flight LPs, as part of crewmember evaluation, has also been considered by NASA. This manuscript summarizes the unique operational considerations, constraints, concerns, and limitations of using traditional LP as an adjunct or as an alternative to noninvasive ICP measurements during spaceflight.

Background: The T-10 parachute has been the U.S. Army standard parachute since 1952 and is now being replaced by the T-11, which has a capacity for heavier loads. This investigation compared injury rates between the two parachute systems during mass tactical parachute training exercises at Fort Bragg, NC.

Methods: Investigators were on the drop zone for all parachute operations. Data on injured jumpers were collected on the drop zone and supplemented with medical records. Operational data were collected from standard reports and weather data were obtained using a Kestrel(®) Model 4500 pocket weather tracker.

Results: There were a total of 131,747 jumps resulting in 1101 injured service members for a crude incidence of 8.4 injuries/1000 jumps. Most injuries (88%) with a known injury mechanism were associated with ground impact. In univariate analysis, risk of injury with the T-10 was 9.1/1000 jumps and that with the T-11 was 5.2/1000 jumps [odds ratio (T-10/T-11) = 1.72, 95% confidence interval (95%CI) = 1.45-2.08, P < 0.01]. Other factors that independently increased injury risk included night jumps, combat loads, higher wind speeds, higher temperatures, certain aircraft, and entanglements. After controlling for these factors in a multivariate analysis, injury risk was still higher for the T-10 parachute when compared to the T-11 [odds ratio (T-10/T-11) = 1.56, 95%CI = 1.28-1.89, P < 0.01). For virtually all strata of the independent risk factors, the T-11 had a lower injury rate.

Conclusion: Compared to the T-10, the T-11 parachute had a lower injury incidence under virtually all the operational conditions examined.

Background: This study examined the uptake and effectiveness of fatigue mitigation guidance material including sleep recommendations for a trip with a westward ultra-long-range flight and return long-range flight.

Methods: There were 52 flight crew (4-pilot crews, mean age 55 yr) who completed a sleep/duty diary and wore an actigraph prior to, during, and after the trip. Primary crew flew the takeoff and landing, while relief crew flew the aircraft during the Primary crew's breaks. At key times in flight, crewmembers rated their fatigue (Samn-Perelli fatigue scale) and sleepiness (Karolinska Sleepiness Scale) and completed a 5-min Psychomotor Vigilance Task.

Results: Napping was common prior to the outbound flight (54%) and did not affect the quantity or quality of in-flight sleep (mean 4.3 h). Primary crew obtained a similar amount on the inbound flight (mean 4.0 h), but Secondary crew had less sleep (mean 2.9 h). Subjective fatigue and sleepiness increased and performance slowed across flights. Performance was faster on the outbound than inbound flight. On both flights, Primary crew were less fatigued and sleepy than Secondary crew, particularly at top of descent and after landing. Crewmembers slept more frequently and had more sleep in the first 24 h of the layover than the last, and had shifted their main sleep to the local night by the second night.

Discussion: The suggested sleep mitigations were employed by the majority of crewmembers. Fatigue levels were no worse on the outbound ultra-long-range flight than on the return long-range flight.