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- Pernett, Frank, 1970-
(författare)
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Hypoxic Blackout in Serial Freediving – Protective Mechanisms and Risk Factors
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Breath-hold diving or freediving exposes the body to stressors such as low oxygen and high carbon dioxide levels in the blood, increased hydrostatic pressure, and cold. The reduction in blood oxygen levels is considered a primary factor for loss of consciousness while diving. This is known as hypoxic blackout. My thesis aimed to enhance the understanding of the factors that lead to hypoxic blackout in serial freediving. This includes studying the physiological mechanisms that protect the body against hypoxia and exploring how hyperventilation affects those mechanisms, with a specific focus on repetitive dives. The protective mechanisms, splenic contraction (Studies I, II) and diving bradycardia (Studies II and IV), were tested in experimental conditions. The effect of hyperventilation on simulated serial dives (Study II) was investigated, and a strategy to identify actual hyperventilation during diving was developed and explored (Study III). A static apnea test allowing identification of individuals at particular risk for blackout was developed (Study IV).The results showed that hypoxia-induced splenic contraction occurs rapidly enough to be protective in long-duration breath-holds (Study I). Serial simulated dives, preceded by short-term hyperventilation, lead to longer apnea duration and progressive oxygen desaturation (Study II). Despite the more severe desaturation resulting from hyperventilation, these consecutive apneas do not show an augmented diving response or splenic contraction. Hyperventilation was also observed when divers intended to avoid it (Studies II, III, and IV). Therefore, the possibility of estimating hyperventilation from the signal of a force sensor attached to a chest belt was explored (Study III). A stronger diving bradycardia and a bigger spleen were found to be protective against hypoxia and are related to slower oxygen desaturation (Study IV). The main conclusion is that oxygenation is impaired by the accumulation of an oxygen debt when consecutive dives are preceded by hyperventilation. The protective mechanisms, such as splenic contraction and the diving response, are beneficial at the individual level but do not offset the increased risk across a series of dives. However, splenic contraction does offer protection even during the first dive of a series. A chest belt-mounted force sensor could be used to identify when freedivers are hyperventilating. Additionally, a novel static apnea ramp test is effective in identifying freedivers who are at a high risk of faster desaturation during freediving.
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| 2. |
- Sjöling, Mats, et al.
(författare)
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Skydiving culture and its relation to injury risks and injury reporting
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Annan publikation (populärvet., debatt m.m.)abstract
- This article explores some aspects of the Swedish skydiving culture and its relation to injury risks and injury reporting. Seventeen skydivers were interviewed and the transcripts were analyzed with latent and manifest content analyses. The reference frame emerging from the narratives encompasses experiences of joy, passion and playfulness; and of injury, suffering and death. The risk of injury is viewed as an integrated element of the recreational activity, counterbalanced by its recreational value. From the text analysis we suggest that Swedish skydiving culture is carried by the local club; not the national association. Though the Swedish Parachute Association has far-reaching powers over the clubs, our findings imply that skydiving culture at the local drop zone and formal and informal hierarchical structures among skydivers are what really decide how rules are enforced, and if incidents and injuries are reported.
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| 3. |
- Westman, Anton, 1972-
(författare)
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Dangers in sport parachuting
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background Sport parachuting is a dangerous recreational activity for which available literature appears unsatisfactory to form a basis for injury prevention. Aim Overall: Explore some risk factors in sport parachuting. Study I: Identify fatal incident and injury mechanisms for skydiving (sport parachuting from aircraft). Study II: Identify fatal incident and injury mechanisms for BASE jumping (sport parachuting from fixed objects) for each of the four fixed object types B-A-S-E (building, antenna, span, earth). Study III: Identify non-fatal incident and injury mechanisms for skydiving. Study IV: Evaluate the validity of a compulsory reporting system among active skydivers. Study V: Explore some aspects of the Swedish skydiving culture and its relation to injury risks and injury reporting. Study VI: Describe the mechanism of incident and injury for a free fall shoulder dislocation.Methods Descriptive epidemiological studies of (I) fatal injury events in Swedish skydiving, (II) fatal injury events in BASE jumping worldwide, and (III) non-fatal injury events in Swedish skydiving. Self-report survey of (IV) Swedish skydivers to measure: Sensitivity, as the proportion of injury events fulfilling the reporting criterion that were actually reported; Specificity, as the proportion of false positives in relation to the defined gold standard. Content analysis of (V) Swedish skydiving participant narratives. First-person narrative and free fall video recordings (VI) of one case.Results Overall: Risk factors associated with “free fall” flight of the human body and recreational usage of parachutes were described. Study I: Fatal risk factors in skydiving included student instability in free fall, leading to unstable parachute activation with subsequent line entanglement or parachute activation failure. Unintentional water landings also contributed to fatalities. Every fourth skydiving fatality survived impact and died during transports or in hospitals. Study II: Fatal risk factors in BASE jumping included parachutist free fall instability, miscalculation of free fall acrobatics, deployment failure by the parachutist, pilot chute malfunction and parachute malfunction. In cliff jumping (BASE object type E), parachute opening towards the object jumped with subsequent collision was a frequent factor. Poor visibility, strong or turbulent winds, cold and water also contributed to BASE jumping fatalities. Study III: Non-fatal risk factors in skydiving included experience level and type of student-training system. The lower extremities, spine and shoulders were important regions of injury. The most serious injuries were seen in experienced skydivers. Study IV: The overall sensitivity of the skydiving injury reporting system was 0.37 (95% confidence interval (CI) 0.24-0.51). With non-minor injuries as the target for reporting, the sensitivity was 0.67 (95% CI 0.43-0.85). No significant effect on reporting was found for gender, age, license level, years in the sport, total number of jumps or club affiliation. The specificity was 0.91 (95% CI 0.83-0.95). Study V: It is suggested that Swedish skydiving culture is carried by the local club; not the national association. Skydiving culture at the local drop zone and formal and informal hierarchical structures among skydivers may be what really decides how rules are enforced, risk-taking behavior is seen, and if incidents and injuries are reported. Study VI: The free fall airstream forces were in this case strong enough to dislocate a shoulder joint, which has safety implications that should be considered by participants and medical doctors performing precourse examinations.Conclusion A number of risk factors in sport parachuting are described. Some technological, training and regulatory interventions are suggested to increase safety.
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| 4. |
- Westman, Anton, 1972-, et al.
(författare)
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Fatalities in Swedish skydiving
- 2005
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 37:6, s. 1040-1048
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Tidskriftsartikel (refereegranskat)abstract
- Exact risk patterns in skydiving fatalities are not well known, but incomplete world injury data indicate that many are preventable. A comprehensive national material for Sweden of 37 skydiving fatalities 1964–2003 were reviewed to identify risk factors. In relation to jump volume, the period 1994–2003 had a fatality rate 11 times lower than 1964–1973. Student skydivers had the highest risk of fatal outcome, often caused by instability in freefall leading to unstable parachute activation with subsequent line entanglement, or parachute activation failure. Unintentional water landings also contributed to student fatality, with life jacket malfunctions, neglect to use life jackets, and automatic reserve parachute activation devices activated by water as aggravating factors. One-third of all fatalities had an inflated and operational parachute at some point prior to injury. A drastic worldwide increase in fatal landing incidents with fast wing parachutes during the 1990s did not occur in Sweden. Every fourth fatality caused by rapid deceleration against ground or water survived impact and died during transports or in hospitals. Rescue units and health care providers can improve management of skydiving incidents from knowledge about the incident and injury mechanisms we have described, and the skydiving community can target risk factors in preventive safety work.
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| 5. |
- Westman, Anton, 1972-, et al.
(författare)
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Injuries in Swedish skydiving
- 2007
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Ingår i: British Journal of Sports Medicine. - : BMJ. - 0306-3674 .- 1473-0480. ; 41:6, s. 356-364
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Westman, Anton, 1972-, et al.
(författare)
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Parachuting from fixed objects : descriptive study of 106 fatal events in BASE jumping 1981-2006
- 2008
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Ingår i: British Journal of Sports Medicine. - Loughborough : British Assoc. of Sport and Medicine. - 0306-3674 .- 1473-0480. ; 42:6, s. 431-436
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To analyse the characteristics of fatal incidents in fixed object sport parachuting (building, antenna, span, earth (BASE) jumping) and create a basis for prevention.Design: Descriptive epidemiological study.Participants: Data on reported fatal injury events (n = 106) worldwide in 1981–2006 retrieved from the BASE fatality list.Assessment of risk factors: Human, equipment and environmental factors.Main outcome measurements: Identification of typical fatal incident and injury mechanisms for each of the four fixed object types of BASE jumping (building, antenna, span, earth).Results: Human factors included parachutist free fall instability (loss of body control before parachute deployment), free fall acrobatics and deployment failure by the parachutist. Equipment factors included pilot chute malfunction and parachute malfunction. In cliff jumping (BASE object type E), parachute opening towards the object jumped was the most frequent equipment factor. Environmental factors included poor visibility, strong or turbulent winds, cold and water. The overall annual fatality risk for all object types during the year 2002 was estimated at about one fatality per 60 participants.Conclusions: Participants in BASE jumping should target risk factors with training and technical interventions. The mechanisms described in this study should be used by rescue units to improve the management of incidents.
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| 7. |
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| 8. |
- Westman, Anton, 1972-, et al.
(författare)
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Validity of injury reporting among active Swedish skydivers
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: Evaluation of a national compulsory reporting system for skydiving injuries.Design: Self-report survey.Setting: The Swedish Parachute Association (SFF).Subjects: All persons renewing a Swedish skydiving license 2008 (n=1049).Main outcome measures: Sensitivity was measured as the proportion of injury events fulfilling the reporting criterion that were actually reported; Specificity was measured as the proportion of false positives in relation to the defined gold standard. Self-stated bone fractures, shoulder dislocations and cruciate ligament injuries were labeled as non-minor injuries.Results: The response rate was 100%. The overall sensitivity of the reporting system 2006/2007 was 0.37 (95% confidence interval (CI) 0.24-0.51). With selfstated non-minor injuries as the target for reporting, the sensitivity was 0.67 (95% CI 0.43-0.85). No significant effect on reporting was found for gender, age, license level, years in the sport, total number of jumps or club affiliation. The specificity was 0.91 (95% CI 0.83-0.95).Conclusions: The low sensitivity will yield false low incidence calculations, but risk comparisons related to the candidate predictor variables appear reasonably valid. The false positive reporting warrants assortment of incoming data and a clarification of the reporting criterions. We propose the addition of “hospitalization Yes/No” in future reporting and endorse coordinating skydiving data collection in the Nordic countries. Further studies on attitudes to reporting are necessary to understand the drivers and constraints for achieving a more complete notification of skydiving injuries.
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