Speed of spleen volume changes evoked by serial apneas

Schagatay, Erika; Haughey, Helena; Reimers, Jenny

doi:10.1007/s00421-004-1224-0

Cited by 81 publications

(135 citation statements)

References 14 publications

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“…The Hb-response was also enhanced in subjects with pronounced SpO 2 reduction after exercise, suggesting that splenic contraction with erythrocyte expulsion is closely related to the degree of hypoxia, in accordance with the study of Richardson et al,2009 [27]. We suggest that spleen contraction with erythrocyte expulsion may attenuate hypoxia during exercise in subjects with COPD, similar to the effect found during apnea [5,7]. An important question is whether the responses observed in the present study will be modified by repeated or prolonged exercise, or by long-term hypoxia.…”

Section: Hb (G/l)supporting

confidence: 78%

“…The mean Hb increase of 3.9 g/L after exercise/ 6MWT in the present study was similar in magnitude compared to previous observations in healthy subjects during apnea [5,7,27], exercise [12] and eupneic hypoxia [13]. This response was more pronounced in COPD subjects with a larger spleen suggesting that spleen volume has an impact on the ability to expel erythrocytes.…”

Section: Hb (G/l)supporting

confidence: 76%

“…The latter finding suggests that this spleen function may be essential for these individuals during hypoxic challenges similar to that found in healthy subjects during maximal exercise [23], high altitude simulation [13,14] or apnea [4,5,7]. In …”

Section: Discussionsupporting

confidence: 60%

“…diving seals, spleen contraction may prolong aerobic dive duration [2,3]. In healthy human subjects, spleen contraction and circulating hemoglobin (Hb) increase have also been observed during apnea [4][5][6][7]. Interestingly, apnea in splenectomized subjects was found not to induce a Hb increase [5], and neonates with asplenia showed impaired transient elevation of blood Hb in response to acute hypoxia [8].…”

Section: Introductionmentioning

confidence: 99%

“…Heart rate (HR) and peripheral oxygen saturation (SpO 2 ) were measured continuously across the protocol, using a portable pulse-oxymeter (Wristox Nonin 9500 Onyx, Nonin Medical Inc., MN, USA). During the resting periods before and directly after the 6MWT, spleen maximal length (L) thickness (T) and width (W) were measured using ultrasonic imaging (Mindray DP-6600, Shenzhen Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China) every minute for volume calculations using the formula Lπ(WT-T 2 )/3 [7] . The formula is based on the average shape of the spleen, and describes the difference between two ellipsoids divided by two.…”

Section: Measurementsmentioning

confidence: 99%

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Exercise induced hemoconcentration following spleen contraction in subjects with COPD

et al. 2015

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Background: The blood-boosting spleen contraction represents a potential protective response to hypoxia by raising the blood gas storage capacity. Human spleen contraction has been observed during exercise, apnea and simulated altitude resulting in ejection of stored red blood cells into circulation. High-altitude exposure has been shown to increase spleen contraction suggesting that long-term hypoxia may improve the response in humans. Subjects with COPD are often exposed to hypoxia, which limits their physical performance. However, it is not known if spleen contraction occurs in subjects with COPD. Our aim was to reveal whether subjects with COPD recruit the spleen erythrocyte reserve during mild exercise. Methods: SpO 2 , spleen volume and Hb were measured before and after 6 min walking test (6MWT) in 24 subjects with COPD. Results were analyzed for all subjects pooled and for subject groups with resting SpO 2 above and below 90 % separated and expressed as mean. Results: 6MWT reduced SpO 2 from 91 to 83 % and spleen volume from 254 to 181 mL, while Hb increased from 150 to 154 g/L (p = 0.001 for all). Compared to subjects with SpO 2 > 90 %, the group with SpO 2 < 90 % displayed the largest resting spleen volume (339 vs 202 mL; p = 0.001) and the most pronounced spleen volume reduction (139 vs 40 mL; p = 0.007). Conclusion: Exercise with hypoxia evokes spleen contraction in subjects with COPD and may represent a protective response during periods of hypoxia. The larger spleen volume and more pronounced contraction in the most hypoxic subjects may suggest long-term adaptation to hypoxia.

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Section: Hb (G/l)supporting

confidence: 78%

Section: Hb (G/l)supporting

confidence: 76%

Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Measurementsmentioning

confidence: 99%

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Exercise induced hemoconcentration following spleen contraction in subjects with COPD

et al. 2015

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Larger spleens and greater splenic contraction during exercise may be an adaptive characteristic of Nepali Sherpa at high‐altitude

Brutsaert,

Harman,

Bigham

et al. 2024

American J Hum Biol

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ObjectivesThe Sherpa ethnic group living at altitude in Nepal may have experienced natural selection in response to chronic hypoxia. We have previously shown that Sherpa in Kathmandu (1400 m) possess larger spleens and a greater apnea‐induced splenic contraction compared to lowland Nepalis. This may be significant for exercise capacity at altitude as the human spleen responds to stress‐induced catecholamine secretion by an immediate contraction, which results in transiently elevated hemoglobin concentration ([Hb]).MethodsTo investigate splenic contraction in response to exercise at high‐altitude (4300 m; Pb = ~450 Torr), we recruited 63 acclimatized Sherpa (29F) and 14 Nepali non‐Sherpa (7F). Spleen volume was measured before and after maximal exercise on a cycle ergometer by ultrasonography, along with [Hb] and oxygen saturation (SpO2).ResultsResting spleen volume was larger in the Sherpa compared with Nepali non‐Sherpa (237 ± 62 vs. 165 ± 34 mL, p < .001), as was the exercise‐induced splenic contraction (Δspleen volume, 91 ± 40 vs. 38 ± 32 mL, p < .001). From rest to exercise, [Hb] increased (1.2 to 1.4 g.dl−1), SpO2 decreased (~9%) and calculated arterial oxygen content (CaO2) remained stable, but there were no significant differences between groups. In Sherpa, both resting spleen volume and the Δspleen volume were modest positive predictors of the change (Δ) in [Hb] and CaO2 with exercise (p‐values from .026 to .037 and R2 values from 0.059 to 0.067 for the predictor variable).ConclusionsLarger spleens and greater splenic contraction may be an adaptive characteristic of Nepali Sherpa to increase CaO2 during exercise at altitude, but the direct link between spleen size/function and hypoxia tolerance remains unclear.

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Breath‐Hold Diving

Fitz‐Clarke

2018

Comprehensive Physiology

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Breath-hold diving is practiced by recreational divers, seafood divers, military divers, and competitive athletes. It involves highly integrated physiology and extreme responses. This article reviews human breath-hold diving physiology beginning with an historical overview followed by a summary of foundational research and a survey of some contemporary issues. Immersion and cardiovascular adjustments promote a blood shift into the heart and chest vasculature. Autonomic responses include diving bradycardia, peripheral vasoconstriction, and splenic contraction, which help conserve oxygen. Competitive divers use a technique of lung hyperinflation that raises initial volume and airway pressure to facilitate longer apnea times and greater depths. Gas compression at depth leads to sequential alveolar collapse. Airway pressure decreases with depth and becomes negative relative to ambient due to limited chest compliance at low lung volumes, raising the risk of pulmonary injury called "squeeze," characterized by postdive coughing, wheezing, and hemoptysis. Hypoxia and hypercapnia influence the terminal breakpoint beyond which voluntary apnea cannot be sustained. Ascent blackout due to hypoxia is a danger during long breath-holds, and has become common amongst high-level competitors who can suppress their urge to breathe. Decompression sickness due to nitrogen accumulation causing bubble formation can occur after multiple repetitive dives, or after single deep dives during depth record attempts. Humans experience responses similar to those seen in diving mammals, but to a lesser degree. The deepest sled-assisted breath-hold dive was to 214 m. Factors that might determine ultimate human depth capabilities are discussed. © 2018 American Physiological Society. Compr Physiol 8:585-630, 2018.

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Speed of spleen volume changes evoked by serial apneas

Cited by 81 publications

References 14 publications

Exercise induced hemoconcentration following spleen contraction in subjects with COPD

Exercise induced hemoconcentration following spleen contraction in subjects with COPD

Larger spleens and greater splenic contraction during exercise may be an adaptive characteristic of Nepali Sherpa at high‐altitude

Breath‐Hold Diving

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