Gas decompression

PURPOSE: To observe the growth and resolution of decompression gas bubbles in the spinal cord of live rats in real time using MRI. METHODS: We constructed an MRI-compatible pressure chamber system to visualize gas bubble dynamics in deep tissues in real time. The system pressurizes and depressurizes rodents inside an MRI scanner and monitors their respiratory rate, heart rate, and body temperature while providing gaseous anesthesia under pressure during the experiments...

INTRODUCTION: High-flow priapism is rare, uncontrolled arterial inflow, preceded by penile or perineal trauma and arterial-lacunar fistula. There are several ways to treat high-flow priapism, i.e., conservative management, the use of ice packs, mechanical decompression, surgery, and super-selective arterial embolization. Embolization is currently widely accepted in patients who fail from conservative management. This study aimed to report the use of Gelfoam and microcoil embolization in recurrent high-flow priapism compared to PVA embolization...

PURPOSE: Ultrasound imaging is commonly used in decompression research to assess venous gas emboli (VGE) post-dive, with higher loads associated with increased decompression sickness risk. This work examines, for the first time in humans, the performance of a novel electrical impedance spectroscopy technology (I-VED), on possible detection of post-dive bubbles presence and arterial endothelial dysfunction that may be used as markers of decompression stress. METHODS: I-VED signals were recorded in scuba divers who performed standardized pool dives before and at set time points after their dives at 35-minute intervals for about two hours...

In-chamber pneumothorax has complicated medically remote professional diving operations, submarine escape training, management of decompression illness, and hospital-based provision of hyperbaric oxygen therapy. Attempts to avoid thoracotomy by combination of high oxygen partial pressure breathing (the concept of inherent unsaturation) and greatly slowed rates of chamber decompression proved successful on several occasions. When this delicate balance designed to prevent the intrapleural gas volume from expanding faster than it contracts proved futile, chest drains were inserted...

Decompression illness is a collective term for two maladies (decompression sickness [DCS] and arterial gas embolism [AGE]) that may arise during or after surfacing from compressed gas diving. Bubbles are the presumed primary vector of injury in both disorders, but the respective sources of bubbles are distinct. In DCS bubbles form primarily from inert gas that becomes dissolved in tissues over the course of a compressed gas dive. During and after ascent ('decompression'), if the pressure of this dissolved gas exceeds ambient pressure small bubbles may form in the extravascular space or in tissue blood vessels, thereafter passing into the venous circulation...

INTRODUCTION: Diving injuries are influenced by a multitude of factors. Literature analysing the full chain of events in diving accidents influencing the occurrence of diving injuries is limited. A previously published 'chain of events analysis' (CEA) framework consists of five steps that may sequentially lead to a diving fatality. This study applied four of these steps to predominately non-lethal diving injuries and aims to determine the causes of diving injuries sustained by divers treated by the Diving Medical Centre of the Royal Netherlands Navy...

Decompression sickness describes the clinical pathology that ensues when rapid decompression from a highly pressurized environment causes the formation of venous and extravascular inert gas bubbles. Symptoms vary widely, commonly including arthralgias, myalgias, paresthesias, and numbness. Severe and potentially life-threatening pathology, such as neurologic impairment, cardiopulmonary instability, and gastrointestinal hemorrhage, can occur as well. Most think of diving endeavors as a common exposure predisposing to this condition, commonly referred to as "the bends...

Underwater activities are characterized by an imbalance between reactive oxygen/nitrogen species (RONS) and antioxidant mechanisms, which can be associated with an inflammatory response, depending on O2 availability. This review explores the oxidative stress mechanisms and related inflammation status (Oxy-Inflammation) in underwater activities such as breath-hold (BH) diving, Self-Contained Underwater Breathing Apparatus (SCUBA) and Closed-Circuit Rebreather (CCR) diving, and saturation diving. Divers are exposed to hypoxic and hyperoxic conditions, amplified by environmental conditions, hyperbaric pressure, cold water, different types of breathing gases, and air/non-air mixtures...

BACKGROUND: Gastric stromal tumors, originating from mesenchymal tissues, are one of the most common tumors of the digestive tract. For stromal tumors originating from the muscularis propria, compared with conventional endoscopic submucosal dissection (ESD), endoscopic full-thickness resection (EFTR) can remove deep lesions and digestive tract wall tumors completely. However, this technique has major limitations such as perforation, postoperative bleeding, and post-polypectomy syndrome...

BACKGROUND: Hepatic portal venous gas (HPVG) is very rare; it is associated with multiple gastrointestinal etiologies, with pathophysiology not yet fully understood. It is characteristically fast-progressing and has a high mortality rate. Treatment choice depends on the etiology, including conservative and surgical management. CASE PRESENTATION: We report an adult patient (less than 25 years old) of HPVG combined with acute upper gastrointestinal hemorrhage, in which massive gas in the hepatic portal vein system by computed tomography of the abdomen was rapidly dissipated by nasogastric decompression conservative management...

Decompression sickness (DCS) is caused by gaseous nitrogen dissolved in tissues forming bubbles during decompression. To date no method exists to identify nitrogen within tissues, but with advances in PET technology it may be possible to track gaseous radionuclides into tissues. We aimed to develop a method to track nitrogen movement in vivo that could then be used to further our understanding of DCS using nitrogen-13 (13 N2 ). A single anesthetized female Sprague Dawley rat, was exposed to 625 kPa, composed of air, isoflurane and 13 N2 for 10 min...

Inflammatory bowel diseases (IBD), with an increasing incidence, pose a significant health burden. Although there have been significant advances in the treatment of IBD, more progress is still needed. Hyperbaric oxygen therapy (HBOT) has been shown to treat a host of conditions such as carbon monoxide poisoning, decompression sickness, and gas gangrene. In the last few years, there has been an increase in research into the use of HBOT as an adjunct to conventional treatment for IBD. Related research has shown that HBOT may exert its therapeutic effects by decreasing oxidative stress, inhibiting mucosal inflammation, promoting ulcer healing, influencing gut microbes, and reducing the incidence of IBD complications...

Forcible wetting of hydrophobic pores represents a viable method for energy storage in the form of interfacial energy. The energy used to fill the pores can be recovered as pressure-volume work upon decompression. For efficient recovery, the expulsion pressure should not be significantly lower than the pressure required for infiltration. Hysteresis of the wetting/drying cycle associated with the kinetic barrier to liquid expulsion results in energy dissipation and reduced storage efficiency. In the present work, we use open ensemble (Grand Canonical) Monte Carlo simulations to study the improvement of energy recovery with decreasing diameters of planar pores...

BACKGROUND: Breathing pure oxygen causes nitrogen washout from tissues, a method commonly deployed to prevent decompression sickness from hypobaric exposure. Theoretically prebreathing oxygen increases the capacity for nitrogen uptake and potentially limits supersaturation during dives of short duration. We aimed to use 13N2, a radioactive nitrogen isotope, to quantify tissue nitrogen following normobaric and hyperbaric exposures. METHODS: Twenty Sprague Dawley rats were divided in 4 conditions; normobaric prebreathe, normobaric control, hyperbaric prebreathe, hyperbaric control...

PURPOSE: Dive-induced cardiac and hemodynamic changes are caused by various mechanisms, and they are aggravated by cold water. Therefore, aging divers with pre-existing cardiovascular conditions may be at risk of acute myocardial infarction, heart failure, or arrhythmias while diving. The aim of this study was to assess the effect of a single decompression CCR dive in arctic cold water on cardiac function in Finnish technical divers. METHODS: Thirty-nine divers performed one identical 45 mfw CCR dive in 2-4 °C water...

Iatrogenic colonic barotrauma is a well-documented entity, mostly due to endoscopic procedures. Compressed air pressure colorectal injury is less frequent, and the exact mechanism is not defined clearly to date. We present our experience of managing high transanal barotrauma to the colorectum in two similar cases presented with massive pneumoperitoneum, pneumothorax, and pneumomediastinum, a rare presentation in emergency departments, with an accident being the common etiology, where both the patients presented with massive abdominal distension and respiratory distress with diffuse subcutaneous emphysema...

Chilaiditi sign is defined as the interposition of the colon or small intestine between the liver and the right diaphragm in the absence of symptoms. Chilaiditi syndrome refers to the condition where the Chilaiditi sign is associated with symptoms including abdominal pain. In this series, we present the cases of two pre-pubescent patients with these rare conditions.  A 10-year-old female with a history of autism, IgA deficiency, and constipation presented for gastrointestinal studies due to weight loss and constipation...

We report the case of a 23-year-old male novice diver who sustained cerebral arterial gas embolism (CAGE) during his open water certification training whilst practising a free ascent as part of the course. He developed immediate but transient neurological symptoms that had resolved on arrival to hospital. Radiological imaging of his chest showed small bilateral pneumothoraces, pneumopericardium and pneumomediastinum. In view of this he was treated with high flow normobaric oxygen rather than recompression, because of the risk of development of tension pneumothorax upon chamber decompression...

INTRODUCTION: Venous gas emboli (VGE) are widely used as a surrogate endpoint instead of decompression sickness (DCS) in studies of decompression procedures. Peak post-dive VGE grades vary widely following repeated identical dives but little is known about how much of the variability in VGE grades is proportioned between-diver and within-diver. METHODS: A retrospective analysis of 834 man-dives on six dive profiles with post-dive VGE measurements was conducted under controlled laboratory conditions...

INTRODUCTION: Quantifying inert gas wash-out is crucial to understanding the pathophysiology of decompression sickness. In this study, we developed a portable closed-circuit device for measuring inert gas wash-out and validated its precision and accuracy both with and without human subjects. METHODS: We developed an exhalate monitor with sensors for volume, temperature, water vapor and oxygen. Inert gas volume was extrapolated from these inputs using the ideal gas law...