Ultrasound detection of lymphatic bubbles in a porcine dive model.

Ultrasound is currently the optimal imaging modality in the decompression research field for assessing intracorporeal gas. Decompression sickness (DCS) is triggered by excess gas bubble presence in the body; however, the relationship is not well understood. Presently, the decompression physiology field does not have a strong predictive DCS biomarker.

Decompression Sickness: Current Recommendations.

Decompression sickness (DCS, "bends") is the clinical condition triggered by generation of bubbles in tissues or blood due to supersaturation of inert gas during or after a reduction in ambient pressure. The condition can occur in association with compressed gas diving, compressed air ("caisson") work or rapid decompression to high altitude or reduced cabin pressure such as extravehicular activity (EVA) in space suits. It can also be triggered by mild reduction in ambient pressure such as during commercial aircraft flight after scuba diving.

Hyperbaric Treatment of Air or Gas Embolism: Current Recommendations.

Gas can enter arteries (arterial gas embolism) due to alveolar-capillary disruption (caused by pulmonary overpressurization, e.g. breath-hold ascent by divers), veins (venous gas embolism, VGE) as a result of tissue bubble formation due to decompression (diving, altitude exposure), or during certain surgical procedures where capillary hydrostatic pressure at the incision site is subatmospheric.

Hyperbaric Oxygen Therapy for Management of Complex Regional Pain Syndrome.

Objectives: Complex regional pain syndrome remains a challenging condition characterized by severe, persistent pain and a variety of inflammatory and trophic symptoms. This study aimed to analyze the current literature to evaluate hyperbaric oxygen therapy (HBOT)'s efficacy in treating complex regional pain syndrome (CRPS), focusing on both sympathetically maintained pain (SMP) and sympathetically independent pain (SIP) subtypes.

Methods: A comprehensive literature search was conducted in PubMed Clinical Queries using the MeSH term "Complex Regional Pain Syndromes" OR the keyword "CRPS" AND "Hyperbaric Oxygen Therapy" OR the keyword "HBOT.

REPRINTED FROM THE 2023 HYPERBARIC INDICATIONS MANUAL 15 Edition:Intracranial Abscess.

The term "intracranial abscess" (ICA) includes cerebral abscess, subdural empyema, and epidural empyema, which share many diagnostic and therapeutic similarities and, frequently, very similar etiologies. Infection may occur and spread from a contiguous infection such as sinusitis, otitis, mastoiditis, or dental infection; hematogenous seeding; or cranial trauma. Brain abscess usually results from predisposing factors such as HIV infection, immunosuppressive drug treatment, surgery, adjacent infection (i.

Elevation of spectral components of electrodermal activity precedes central nervous system oxygen toxicity symptoms in divers.

Background: Oxygen-rich breathing mixtures up to 100% are used in some underwater diving operations for several reasons. Breathing elevated oxygen partial pressures (PO) increases the risk of developing central nervous system oxygen toxicity (CNS-OT) which could impair performance or result in a seizure and subsequent drowning. We aimed to study the dynamics of the electrodermal activity (EDA) and heart rate (HR) while breathing elevated PO in the hyperbaric environment (HBO) as a possible means to predict impending CNS-OT.

Pushing Scuba to New Heights: Approach, Decompression, and Logistical Considerations for High-Altitude Diving.

Yoder, Taylor L., Kreager A. Taber, Laurens E.

Effects of submersion on VO: comparing maximum aerobic exertion on land and underwater.

Introduction: Submersion results in blood redistribution into the pulmonary circulation, causing changes in pulmonary compliance and increased cardiac preload. Few studies have compared incremental exercise to exhaustion (VO max testing) in a dry environment with exercise underwater. We hypothesized that the physiological effects of submersion would result in lower heart rate (HR), minute ventilation (V), and peak oxygen uptake (VO peak) compared with dry conditions.

Relative hypoxemia at depth during breath-hold diving investigated through arterial blood gas analysis and lung ultrasound.

Pulmonary gas exchange in breath-hold diving (BHD) consists of a progressive increase in arterial partial pressures of oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]) during descent. However, recent findings have demonstrated that [Formula: see text] does not consistently rise in all subjects. This study aimed at verifying and explaining [Formula: see text] derangements during BHD analyzing arterial blood gases and searching for pulmonary alterations with lung ultrasound.

Development of a graphical user interface for automatic separation of human voice from Doppler ultrasound audio in diving experiments.

Doppler ultrasound (DU) is used in decompression research to detect venous gas emboli in the precordium or subclavian vein, as a marker of decompression stress. This is of relevance to scuba divers, compressed air workers and astronauts to prevent decompression sickness (DCS) that can be caused by these bubbles upon or after a sudden reduction in ambient pressure. Doppler ultrasound data is graded by expert raters on the Kisman-Masurel or Spencer scales that are associated to DCS risk.

Effect of Anesthetic Carrier Gas on In Vivo Circulation Times of Intravenously Administered Phospholipid Oxygen Microbubbles in Rats.

Objective: For the treatment of tumor hypoxia, microbubbles comprising oxygen as a majority component of the gas core with a stabilizing shell may be used to deliver and release oxygen locally at the tumor site through ultrasound destruction. Previous work has revealed differences in circulation half-life in vivo for perfluorocarbon-filled microbubbles, typically used as ultrasound imaging contrast agents, as a function of anesthetic carrier gas. These differences in circulation time in vivo were likely due to gas diffusion as a function of anesthetic carrier gas, among other variables.

Volume 50: The UHM Journal celebrates a milestone with the publication of this issue.

As the UHMS observes the distinguished anniversary of the publication of 50 volumes of the Undersea and Hyperbaric Medicine Journal, two of our past editors take a look at the evolution of our flagship publications.

Deep Learning-Based Venous Gas Emboli Grade Classification in Doppler Ultrasound Audio Recordings.

Objective: Doppler ultrasound (DU) is used to detect venous gas emboli (VGE) post dive as a marker of decompression stress for diving physiology research as well as new decompression procedure validation to minimize decompression sickness risk. In this article, we propose the first deep learning model for VGE grading in DU audio recordings.

Methods: A database of real-world data was assembled and labeled for the purpose of developing the algorithm, totaling 274 recordings comprising both subclavian and precordial measurements.

Effects of high-intensity interval training with hyperbaric oxygen.

Hyperbaric Oxygen (HBO) has been proposed as a pre-conditioning method to enhance exercise performance. Most prior studies testing this effect have been limited by inadequate methodologies. Its potential efficacy and mechanism of action remain unknown.

Safety evaluation of carbon tetrafluoride as an inert hyperbaric breathing gas in Sprague-Dawley rats.

Carbon tetrafluoride (CF) is an inert gas with higher molecular weight and lower water solubility than commonly used hyperbaric breathing gases. These inert gas properties decrease time required to decompress and avoid decompression sickness after deep dives. To assess CF toxicity, Sprague-Dawley rats were exposed to 8 atm absolute (ATA) air (10 males, 10 females) or 8 ATA 79% CF/21% O (25 males, 25 females).

Immersion-Induced Mitral Regurgitation: A Novel Risk Factor for Swimming-Induced Pulmonary Edema.

Immersion pulmonary edema, more commonly referred to as swimming-induced pulmonary edema (SIPE), is a well-documented condition believed to be a result of immersion physiologic condition that is characterized by a peripheral-to-central redistribution of blood volume. It disproportionally affects young, healthy athletes with no clinically overt cardiovascular or pulmonary conditions. We present four cases of healthy athletes with previously documented SIPE, who participated in Institutional Review Board-approved clinical studies that examined the pathophysiologic condition and prevention of SIPE.

Blood gas analyses in hyperbaric and underwater environments: a systematic review.

Pulmonary gas exchange during diving or in a dry hyperbaric environment is affected by increased breathing gas density and possibly water immersion. During free diving, there is also the effect of apnea. Few studies have published blood gas data in underwater or hyperbaric environments: this review summarizes the available literature and was used to test the hypothesis that arterial Po under hyperbaric conditions can be predicted from blood gas measurement at 1 atmosphere assuming a constant arterial/alveolar Po ratio (a:A).