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Conclusions: Barotrauma was observed in breath-hold divers who increased their lung volumes by GI. The long-term effects of this barotrauma are uncertain and longitudinal studies are required to assess cumulative lung damage. (Source: Respirology)

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CIH: from sleep apnea to breath-hold diving : Is sympathetic activation inevitable?
Clin Auton Res. 2010 Apr 20;
Authors: Chapleau MW

PMID: 20405161 [PubMed - as supplied by publisher]

We report on a Japanese male professional breath-hold diver (Ama) who developed neurological disorders during repetitive dives to 22 meters of sea water. Each diving duration and surface interval were 40-80 seconds and 20-30 seconds, respectively. He suffe... (Source: SafetyLit: All (Unduplicated))

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Energetics of breath-hold hunting: Modeling the effects of aging on foraging success in the Weddell seal.
J Theor Biol. 2010 Apr 1;
Authors: Hindle AG, Horning M
A simulation model was developed to predict age-related changes in foraging energetics of individual Weddell seals, Leptonychotes weddellii. Aging in diving animals is interesting because their characteristic cyclic sequence of apneustic hunting and eupnea should elevate oxidative stress, possibly accelerating aging. Such a hypothesis can be evaluated by modeling energetics of constrained, time-partitioned activities with well-defined costs. Three possible consequences of physiological aging in divers were specified and appraised. The model examined the potential impacts of age-related decline in muscle contractile ability, increased buoyancy, and reduced aerobic dive limit, alone and in combination, on a daily energy budget. A uniform age effect evident in model outputs is reduced foraging efficiency. The components of this…

(Source: Aviation, Space, and Environmental Medicine)

Decompression sickness in breath-hold divers: A review.
J Sports Sci. 2009 Dec 3;:1-16
Authors: Lemaitre F, Fahlman A, Gardette B, Kohshi K
Although it has been generally assumed that the risk of decompression sickness is virtually zero during a single breath-hold dive in humans, repeated dives may result in a cumulative increase in the tissue and blood nitrogen tension. Many species of marine mammals perform extensive foraging bouts with deep and long dives interspersed by a short surface interval, and some human divers regularly perform repeated dives to 30-40 m or a single dive to more than 200 m, all of which may result in nitrogen concentrations that elicit symptoms of decompression sickness. Neurological problems have been reported in humans after single or repeated dives and recent necropsy reports in stranded marine mammals were suggestive of decompression sickness-like symptoms. Modelling attempts have suggested that marine mammals may live permanently with elevated nitrogen concentrations …

Linér MH, Andersson JPA. Hypoxic syncope in a competitive breath-hold diver with elevation of the brain damage marker S100B. Aviat Space Environ Med 2009; 80:1066-8.
Introduction: Competitive breath-hold divers can accomplish previously unbelievable performances; e.g., the current world record for apnea during rest (“static apnea”) is 11 min 35 s. However, whether such performances are associated with a risk for hypoxic brain damage has not been established. Case Report: A breath-hold diver's competitive performance resulted in a loss of consciousness, after which he was subjected to a medical examination by the event physician. Blood samples were collected for analysis of the brain damage marker S100B in serum. The S100B in serum was 0.100 μg · L−1 in the blood sample collected 15 min after the loss of consciousness. At 1 and 5 d after the incident it was 0.097 μg · L−1 and 0.045 μg · L−1, respectively. Discussion: The elevated level of S10…

This study was conducted to determine whether ventilatory parameters would change in breath-hold divers (BHDs) after they performed the glossopharyngeal technique for lung insufflation. Fifteen elite BHDs, 16 non-expert BHDs and 15 control subjects participated in this cross-sectional study. Volumes and expiratory flow rates were measured twice, before and after the glossopharyngeal technique performed at rest. Before the technique, greater forced vital capacity (FVC) and forced expiratory volume in 1_s (FEV1) and lower FEV1/FVC were noted in the elite and non-expert BHDs compared with controls. No difference was noted regarding the other pulmonary parameters. After the technique, increases were noted in FVC, FEV1 and maximal voluntary ventilation in the elite BHDs (P_<&n...

In conclusion, direct measurements of ABP during apnea diving showed no or only mild increases in ABP. However, our results cannot be extended over environmental conditions different from those of the present study. (Source: Journal of Applied Physiology)

We report a case with a breath-hold diver who inadvertently experienced a packing blackout. During the incident, an electrocardiogram (ECG) and blood pressure were recorded, and blood samples for determinations of biomarkers of cardiac muscle perturbation (creatine kinase-MB isoenzyme (CK-MB), cardiac troponin-T (TnT), and myoglobin) were collected. The ECG revealed short periods of asystole during the period of 'packing blackout', simultaneous with pronounced reductions in systolic, diastolic, and pulse pressures. Serum myoglobin concentration was elevated 40 and 150 min after the incident, whereas there were no changes in CK-MB or TnT. The ultimate cause of syncope in this diver probably was a decrease in cerebral perfusion following glossopharyngeal insufflation. The asystolic periods r...

Cardiovascular changes during maximal breath-holding in elite divers.
Clin Auton Res. 2009 Aug 5;
Authors: Guaraldi P, Serra M, Barletta G, Pierangeli G, Terlizzi R, Calandra-Buonaura G, Cialoni D, Cortelli P
During maximal breath-holding six healthy elite breath-hold divers, after an initial 'easy-going' phase in which cardiovascular changes resembled the so-called 'diving response', exhibited a sudden and severe rise in blood pressure during the 'struggle' phase of the maneuver. These changes may represent the first tangible expression of a defense reaction, which overrides the classic diving reflex, aiming to reduce the hypoxic damage and to break the apnea before the loss of consciousness.
PMID: 19655193 [PubMed - as supplied by publisher]

Conclusion: These results confirm that elite divers present a potentiation of the well-known apnoea response in both SA and DA conditions. This response is associated with higher brain perfusion which may partly explain the high levels of world apnoea records. (Source: Acta Physiologica)

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Time course of carbon monoxide transfer factor after breath-hold diving.
Undersea Hyperb Med. 2009 Mar-Apr;36(2):93-101
Authors: Prediletto R, Fornai E, Catapano G, Carli C, Garbella E, Passera M, Cialoni D, Bedini R, L'Abbate A
Breath-hold divers may experience haemoptysis during diving. Central pooling of blood as well as compression of pulmonary gas content can damage the integrity of the blood-gas barrier, resulting in alveolar hemorrhage. The single-breath carbon monoxide test (DL,CO) was used to investigate the blood-gas barrier following diving. The study population consisted of 30 divers recruited from a training course. DL,CO levels were measured before diving and at 2, 10 and 25 min after the last of a series of four dives to depths of 10, 15, 20 and 30 m. When compared to pre-diving values, DL,CO values increased significantly at 2 min following diving in all subjects except one. Thereafter values progressively decreased toward baseline at 10 and 25 min in all subjects but…

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Facial immersion in cold water enhances cerebral blood velocity during breathhold exercise in humans.
J Appl Physiol. 2009 Jan 29;
Authors: Kjeld T, Pott FC, Secher NH
The diving response is initiated by apnea and facial immersion in cold water and includes, besides bradycardia, peripheral vasoconstriction, while cerebral perfusion may be enhanced. This study evaluated whether facial immersion in 10 degrees C water has an independent influence on cerebral perfusion evaluated as the middle cerebral artery mean flow velocity (MCA Vmean) during exercise in nine male subjects. At rest, a breath-hold of maximum duration increased the arterial carbon dioxide tension (PaCO2) from 4.2 to 6.7 kPa and MCA Vmean from 37 to 103 cm(.)s(-1) mean (~178%; P0.001). Similarly, during 100 W exercise, a breathhold increased PaCO2 from 5.9 to 8.2 kPa (P0.001) and MCA Vmean from 55 to 113 cm(.)s(-1) (~105%) and facial immersion further increased MCA Vmean to 122 cm(.)s(-1) (~88%; both P0.001). MCA Vmean a…

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Lung compression effects on gas exchange in human breath-hold diving.
Respir Physiol Neurobiol. 2008 Dec 24;
Authors: Fitz-Clarke JR
Lung compression during breath-hold diving reduces gas exchanging surface area. Beyond a critical depth, collapse of all alveoli should result in total pulmonary shunt and a drop in arterial oxygen partial pressure toward the mixed-venous level. The effect of lung collapse on human breath-hold diving capability is analysed using a computational model of the lungs and circulation that simulates oxygen, carbon dioxide, and nitrogen exchange between alveoli, blood, and tissues. Gas uptake during descent becomes limited by lung compression when the ratio of diffusing capacity to the product of perfusion and gas solubility in blood drops below one. An equation is derived for estimating collapse depth due to direct alveolar compression and time-dependent absorption atelectasis. Oxygen dissolved in blood during descent builds a limited capacitive store for sup…

This is a brief overview of physiological reactions, limitations, and pathophysiological mechanisms associated with human breath-hold diving. Breath-hold duration and ability to withstand compression at depth are the two main challenges that have been overcome to an amazing degree as evidenced by the current world records in breath-hold duration at 10:12 min and depth of 214 m. The quest for even further performance enhancements continues among competitive breath-hold divers, even if absolute physiological limits are being approached as indicated by findings of pulmonary edema and alveolar hemorrhage postdive. However, a remarkable, and so far poorly understood, variation in individual disposition for such problems exists. Mortality connected with breath-hold diving is primarily concentrated to less well-trained recreational divers and competitive spearfishermen who fall victim to hypoxia. Particularly vulnerable are probably also individuals with preexisting cardiac problems and possibly, essentially heal…

In conclusion, ectopic arrhythmias were common during maximal static apneas for training purposes. The results indicate that the occurrence of ectopic beats is associated with individual factors such as the tolerable SaO2 decrease. Content Type Journal ArticleCategory Original ArticleDOI 10.1007/s00421-008-0945-xAuthors Jochen Hansel, University of Tuebingen Department of Sports Medicine, Medical Clinic and Policlinic 72076 Tuebingen GermanyIsabelle Solleder, University of Tuebingen Department of Sports Medicine, Medical Clinic and Policlinic 72076 Tuebingen GermanyWilfried Gfroerer, University of Tuebingen Department of Sports Medicine, Medical Clinic and Policlinic 72076 Tuebingen GermanyClaus M. Muth, University Hospital Department of Experimental Anaesthesiology Ulm GermanyKlaus ...

We report the case of a young breath-hold diver who developed spontaneous, non compressive orbital emphysema during underwater fishing, with a maximal depth of 25-30 meters in the Sardinian sea. He was otherwise healthy, without previous cranio-facial trauma and nasosinusal diseases or surgery were not present in the history. When he was referred to our attention the patient presented right eyelid ptosis but diplopia and vision impairment were absent. Computer tomography scans showed subcutaneous air in the right upper eyelid and around the eyeball, particularly near the orbit's roof but optic nerve area, intraconal, was free of air. A dehiscence in lamina papyracea was evident. In our opinion, this has been the point of air entry into the orbit. A supportive therapy was advised and two we...

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To define the dynamics of cardiovascular adjustments to apnoea, beat-to-beat heart rate (HR) and blood pressure and arterial oxygen saturation (SaO2) were recorded during prolonged breath-holding in air in 20 divers. Apnoea had a mean duration of 210_±_70_s. In all subjects, HR attained a value 14_beats_min−1 lower than control within the initial 30_s (phase I). HR did not change for the following 2–2.5_min (phase II). Then, nine subjects interrupted the apnoea (group A), whereas 11 subjects (group B) could prolong the breath-holding for about 100_s, during which HR continuously decreased (phase III). In both groups, mean blood pressure was 8_mmHg above control at the end of phase I; it then further increased by additional 12_mmHg at the end of the apnoea. In both groups, SaO2 did not change in the initial 100–140_s of apnoea; then, it decreased to 95
t the end of phase II. In group B, SaO2 further diminished to 84
t the end of phase III. A typical pattern of cardiovascular readjustmen…