Pre-Dive Exercise and Post-Dive Evolution of Venous Gas Emboli

Gennser, Mikael; Jurd, KM; Blogg, S. Lesley

doi:10.3357/asem.2893.2012

Cited by 15 publications

(15 citation statements)

References 6 publications

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Section: Discussionmentioning

confidence: 97%

“…The statistically insignificant change in BG following the exercise dive compared to the control dive is in line with previous research using similar open sea diving protocols. The impact of exercise on VGE is positive in some studies, although none of these can be directly compared to this experiment as they utilized simulated diving (Gennser et al, 2012) or diving profiles that utilized decompressions stops (Castagna et al 2011). One study with rats utilized a relatively extreme downhill running protocol (100 min at À16°) to induce myofibrillar damage and found no difference in bubble amounts or survival rates following a simulated dive (Jorgenson et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Venous gas emboli are often used as a surrogate marker for decompression stress following exercise; however, the data on VGE and exercise are limited to a few conflicting field studies (Blatteau et al, 2005;Castagna et al, 2011;Madden et al, 2014) and simulated dives (Dujic et al, 2004;Gennser et al, 2012). MPs and endothelial function show promise as other markers to assess decompression stress and these may contribute to DCS or other forms of illness with mechanisms separate from circulating gas emboli.…”

Section: Introductionmentioning

confidence: 99%

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The impact of predive exercise on repetitive SCUBA diving

Madden

Barak

Thom

et al. 2014

Clin Physio Funct Imaging

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The impact of predive exercise on repetitive SCUBA diving

Madden

Barak

Thom

et al. 2014

Clin Physio Funct Imaging

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“…It should be noted that the bubble grades observed following the supine control treatments (C1–C3) were surprisingly low. The dive profile chosen for the study (United Kingdom Royal Navy Table 11) has been used to provoke bubbles in a number of trials investigating prophylactic measures to guard against DCS ( Blogg et al, 2010 , 2017 ; Jurd et al, 2011 ; Gennser et al, 2012 ), as it is known to regularly produce VGE loads across the complete range of the KM grading scale, but with a low incidence of DCS. However, in the present study, hardly any bubbles were produced following the control HE.…”

Section: Discussionmentioning

confidence: 99%

“…The reason for this scarcity of bubbles is not known but could be explained to some extent by the fact that the subjects in the present study were all young and fit (mean age 23 and mean BMI 23.4), which is in contrast to other studies. For example in the study by Gennser et al (2012) , the mean age of the subjects was 40 years, with a mean BMI of 27.7. Further, Conkin et al (2003) found that age was significantly related to VGE load, with younger subjects having fewer bubbles.…”

Section: Discussionmentioning

confidence: 99%

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Gennser

Blogg²,

Eiken

et al. 2018

Front. Physiol.

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Human extravehicular activity (EVA) is essential to space exploration and involves risk of decompression sickness (DCS). On Earth, the effect of microgravity on physiological systems is simulated in an experimental model where subjects are confined to a 6° head-down bed rest (HDBR). This model was used to investigate various resting and exercise regimen on the formation of venous gas emboli (VGE), an indicator of decompression stress, post-hyperbaric exposure. Eight healthy male subjects participating in a bed rest regimen also took part in this study, which incorporated five different hyperbaric exposure (HE) interventions made before, during and after the HDBR. Interventions i–iv were all made with the subjects lying in 6° HD position. They included (C1) resting control, (C2) knee-bend exercise immediately prior to HE, (T1) HE during the fifth week of the 35-day HDBR period, (C3) supine cycling exercise during the HE. In intervention (C4), subjects remained upright and ambulatory. The HE protocol followed the Royal Navy Table 11 with 100 min spent at 18 m (280 kPa), with decompression stops at 6 m for 5 min, and at 3 m for 15 min. Post-HE, regular precordial Doppler audio measurements were made to evaluate any VGE produced post-dive. VGE were graded according to the Kisman Masurel scale. The number of bubbles produced was low in comparison to previous studies using this profile [Kisman integrated severity score (KISS) ranging from 0–1], and may be because subjects were young, and lay supine during both the HE and the 2 h measurement period post-HE for interventions i–iv. However, the HE during the end of HDBR produced significantly higher maximum bubble grades and KISS score than the supine control conditions (p < 0.01). In contrast to the protective effect of pre-dive exercise on bubble production, a prolonged period of bed rest prior to a HE appears to promote the formation of post-decompression VGE. This is in contrast to the absence of DCS observed during EVA. Whether this is due to a difference between hypo- and hyperbaric decompression stress, or that the HDBR model is a not a good model for decompression sensitivity during microgravity conditions will have to be elucidated in future studies.

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Exercise-induced myofibrillar disruption with sarcolemmal integrity prior to simulated diving has no effect on vascular bubble formation in rats

et al. 2012

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Decompression sickness is initiated by gas bubbles formed during decompression, and it has been generally accepted that exercise before decompression causes increased bubble formation. There are indications that exercise-induced muscle injury seems to be involved. Trauma-induced skeletal muscle injury and vigorous exercise that could theoretically injure muscle tissues before decompression have each been shown to result in profuse bubble formation. Based on these findings, we hypothesized that exercise-induced skeletal muscle injury prior to decompression from diving would cause increase of vascular bubbles and lower survival rates after decompression. In this study, we examined muscle injury caused by eccentric exercise in rats prior to simulated diving and we observed the resulting bubble formation. Female Sprague-Dawley rats (n = 42) ran downhill (-16º) for 100 min on a treadmill followed by 90 min rest before a 50-min simulated saturation dive (709 kPa) in a pressure chamber. Muscle injury was evaluated by immunohistochemistry and qPCR, and vascular bubbles after diving were detected by ultrasonic imaging. The exercise protocol resulted in increased mRNA expression of markers of muscle injury; αB-crystallin, NF-κB, and TNF-α, and myofibrillar disruption with preserved sarcolemmal integrity. Despite evident myofibrillar disruption after eccentric exercise, no differences in bubble amounts or survival rates were observed in the exercised animals as compared to non-exercised animals after diving, a novel finding that may be applicable to humans.

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Pre-Dive Exercise and Post-Dive Evolution of Venous Gas Emboli

Cited by 15 publications

References 6 publications

The impact of predive exercise on repetitive SCUBA diving

The impact of predive exercise on repetitive SCUBA diving

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Exercise-induced myofibrillar disruption with sarcolemmal integrity prior to simulated diving has no effect on vascular bubble formation in rats

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