Alf O Brubakk

Alf O Brubakk
Norwegian University of Science and Technology | NTNU · Department of Circulation and Medical Imaging

Professor Applied Physiology

About

153
Publications
13,413
Reads
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4,696
Citations
Citations since 2016
2 Research Items
1064 Citations
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2016201720182019202020212022050100150200
2016201720182019202020212022050100150200
2016201720182019202020212022050100150200

Publications

Publications (153)
Article
Full-text available
The pathophysiological mechanism of decompression sickness is not fully understood but there is evidence that it can be caused by intravascular and autochthonous bubbles. Doppler ultrasound at a given circulatory location is used to detect and quantify the presence of intravascular gas bubbles as an indicator of decompression stress. In this manusc...
Article
Gas bubble lesions consistent with decompression sickness in marine mammals were described for the first time in beaked whales stranded in temporal and spatial association with military exercises. Putrefaction gas is a post-mortem artifact, which hinders the interpretation of gas found at necropsy. Gas analyses have been proven to help differentiat...
Article
Full-text available
The following describes my professional life up till today, but it also describes what I think lies ahead. I have led an interesting professional life and been lucky enough to be at the centre of some of the important development in modern medicine and diving, namely ultrasound in cardiology and the mechanisms of decompression. I therefore should b...
Article
In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia...
Article
Full-text available
Diving often causes the formation of 'silent' bubbles upon decompression. If the bubble load is high, then the risk of decompression sickness (DCS) and the number of bubbles that could cross to the arterial circulation via a pulmonary shunt or patent foramen ovale increase. Bubbles can be monitored aurally, with Doppler ultrasound, or visually, wit...
Article
Full-text available
Hyperbaric oxygen preconditioning (HBO-PC) can protect the heart from injury during subsequent ischemia. The presence of high loads of venous gas emboli (VGE) induced by a rapid ambient pressure reduction on ascent from diving may cause ischemia and acute heart failure. The aim of this study was to investigate the effect of diving-induced VGE forma...
Article
Full-text available
During scuba diving, the circulatory system is stressed by an elevated partial pressure of oxygen while the diver is submerged and by decompression-induced gas bubbles on ascent to the surface. This diving-induced stress may trigger decompression illness, but the majority of dives are asymptomatic. In this study we have mapped divers' blood transcr...
Article
Full-text available
During scuba diving, the circulatory system is stressed by an elevated partial pressure of oxygen while the diver is submerged and by decompression-induced gas bubbles on ascent to the surface. This diving-induced stress may trigger decompression illness, but the majority of dives are asymptomatic. In this study we have mapped divers' blood transcr...
Article
Full-text available
Vascular bubble formation after decompression contributes to endothelial injuries which form the basis for the development of decompression sickness (DCS). Nitric oxide (NO) is a powerful vasodilator that contributes to vessel homeostasis. It has been shown that NO-releasing agent may reduce bubble formation and prevent serious decompression sickne...
Article
Full-text available
In this study, the effect of a simulated dive on rat brain was investigated using several magnetic resonance imaging (MRI)-methods and immunohistochemistry. Rats were randomly assigned to a dive- or a control group. The dive group was exposed to a simulated air dive to 600 kPa for 45 min. Pulmonary artery was monitored for vascular gas bubbles by u...
Article
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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...
Article
Full-text available
Diving causes a transient reduction of vascular function, but the mechanisms behind this are largely unknown. The aim of this study was therefore to analyze genetic reactions that may be involved in acute changes of vascular function in divers. Rats were exposed to 709 kPa of hyperbaric air (149 kPa PO(2)) for 50 minutes followed by post-dive monit...
Article
Full-text available
Gas embolism can arise from different causes (iatrogenic accidents, criminal interventions, or diving related accidents). Gas analyses have been shown to be a valid technique to differentiate between putrefaction gases and gas embolism. In this study, we performed systematic necropsies at different postmortem times in three experimental New Zealand...
Article
This paper is based on a comprehensive dynamic mathematical model (Copernicus) of vascular bubble formation and growth during and after decompression from a dive. The model is founded on the statistical correlation between measurable venous gas emboli (VGE) and risk of severe decompression sickness (DCS) where VGE has been shown to be a reliable an...
Article
Full-text available
Skin and ear infections, primarily caused by Pseudomonas aeruginosa (P. aeruginosa), are recurrent problems for saturation divers, whereas infections caused by P. aeruginosa are seldom observed in healthy people outside saturation chambers. Cystic fibrosis (CF) patients suffer from pulmonary infections by P. aeruginosa, and it has been demonstrated...
Article
Full-text available
Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N(2))...
Article
Full-text available
Decompression sickness (DCS; 'the bends') is a disease associated with gas uptake at pressure. The basic pathology and cause are relatively well known to human divers. Breath-hold diving marine mammals were thought to be relatively immune to DCS owing to multiple anatomical, physiological and behavioural adaptations that reduce nitrogen gas (N 2) l...
Article
Testing of decompression procedures has been performed both in the dry and during immersion, assuming that the results can be directly compared. To test this, the aim of the present paper was to compare the number of venous gas bubbles observed following a short, deep and a shallow, long air dive performed dry in a hyperbaric chamber and following...
Article
Full-text available
Erratum to: Eur J Appl PhysiolDOI 10.1007/s00421-011-1998-9An incorrect citation was included in the originalpublication:Vince RV, Chrismas B, Midgley AW, McNaughton LR,Madden LA (2009) Hypoxia mediated release of endo-thelial microparticles and increased association ofS100A12 with circulating neutrophils. Oxid Med CellLongev 2:2–6The correct refer...
Article
Full-text available
A key process in the pathophysiological steps leading to decompression sickness (DCS) is the formation of inert gas bubbles. The adverse effects of decompression are still not fully understood, but it seems reasonable to suggest that the formation of venous gas emboli (VGE) and their effects on the endothelium may be the central mechanism leading t...
Article
Full-text available
Decompression modeling of divers is a research field that is over 100 years old and since the beginning has been studied mainly as a clinical and biomedical problem. The topic is largely unexplored by the technological sciences using methods and theories for modeling and control. This article outlines a structure where the process of bubble formati...
Article
Full-text available
When neurological damage occurs in divers, it is considered to be caused by gas bubbles. Entrapment of these bubbles may lead to cellular injury and cerebral oedema. S100B is a protein biomarker that is released in CNS injuries and the concentration is related to the amount of brain damage. A total of 27 rats were randomly assigned to one of three...
Article
Individual differences, physiological pre-conditions and in-dive conditions like workload and body temperature have been known to influence bubble formation and risk of decompression sickness in diving. Despite this fact, such effects are currently omitted from the decompression algorithms and tables that are aiding the divers. There is an apparent...
Article
During SCUBA diving, breathing at increased pressure leads to a greater tissue gas uptake. During ascent, tissues may become supersaturated, and the gas is released in the form of bubbles that typically occur on the venous side of circulation. These venous gas emboli (VGE) are usually eliminated as they pass through the lungs, although their occasi...
Conference Paper
Full-text available
DESIGN Fifty-six female Sprague-Dawley rats were exposed to 700 kPa breathing air for 50 minutes with 50 kPa min -1 linear decompression to surface. Nine non-diving animals were included as controls. Gas bubble grade in the pulmonary artery was measured by Doppler ultrasound at discrete time points for 60 min after decompression. Blood samples were...
Article
Diving and decompression performed under immersed conditions have been shown to reduce cardiac function. The mechanisms for these changes are not known. The effect of immersion before a simulated hyperbaric dive on cardiomyocyte function was studied. Twenty-three rats were assigned to four groups: control, 1 h thermoneutral immersion, dry dive, and...
Article
Full-text available
Heat stress prior to diving has been shown to confer protection against endothelial damage due to decompression sickness. Several lines of evidence indicate a relation between such protection and the heat shock protein (HSP)70 and HSP90 and the major cellular red-ox determinant, glutathione (GSH). The present study has used human endothelial cells...
Article
Decompression Sickness (DCS) may occur when divers decompress from a hyperbaric environment. To prevent this, decompression procedures are used to get safely back to the surface. The models whose procedures are calculated from, are traditionally validated using clinical symptoms as an endpoint. However, DCS is an uncommon phenomenon and the wide va...
Article
Recently, an increase in extravascular lung water (EVLW) accumulation with diminished left ventricular contractility within 60 min after SCUBA diving was reported. We have observed previously that diving was associated with reduced diffusing lung capacity for carbon monoxide (DLCO) and arterial oxygen pressure for up to 60-80 min postdive. Here we...
Article
Full-text available
Several studies have demonstrated an adverse effect of bubbles on endothelial function. The degree of dysfunction appears to be related to the number of bubbles present. The aim of the study was to determine whether decompression without bubble formation visible by ultrasound had any effect on arterial endothelial function. We decompressed 21 Sprag...
Article
Full-text available
Although decompression procedures have been improved over the years, decompression still remains a significant problem in diving. While there is universal agreement that the basic problem of decompression is gas coming out of solution, forming bubbles when pressure is reduced, the exact mechanism of decompression injury is not known. Furthermore, t...
Article
Full-text available
Most knowledge about cellular and molecular adaptation in the heart after exercise training comes from rodent models, and this has substantially improved our knowledge about exercise-induced cardiac adaptations. However, in rodents, the electrophysiological properties of the heart are different from the human heart. Therefore, the need of exercise-...
Article
Full-text available
Accumulated inert gas during a dive and subsequent reduction of ambient pressure may lead to formation of gas bubbles, which is the initial cause of decompression sickness (DCS). Decompression procedures are used to get divers safely up from depth, and traditionally, the algorithms are evaluated against clinical symptoms of DCS. However, this appro...
Article
Self-contained underwater breathing apparatus diving reduces cardiovascular function and increases pulmonary artery pressure (PAP) up to 3 days after a single dive. Acute antioxidants partially attenuated arterial endothelial dysfunction, whereas cardiac and PA functions were unaffected. We tested the hypothesis that acute tetrahydobiopterin (BH(4)...
Article
Full-text available
It has been shown that a single bout of exercise performed 20 hours prior to hyperbaric exposure reduces bubble formation and increases survival in rats. Heat shock proteins (HSPs) are stress proteins expressed in cells that are exposed to different stressors. HSPs are known to protect cells, by binding to proteins and stabilizing them. As it is kn...
Article
Full-text available
Most decompression procedures induce the formation of asymptomatic venous gas bubbles. They can be classified as "silent bubbles," which are asymptomatic compared to paradoxical arterialization of venous gas emboli, which can lead to serious neurologic damage. The penetration of such gas bubbles into the arterial circulation is due to pulmonary bar...
Article
Full-text available
The fact that impaired endothelial-dependent vasodilatation after scuba diving often occurs without visible changes in the endothelial layer implies its biochemical origin. Since Lewisx(CD15) and sialyl-Lewisx(CD15s) are granulocyte and monocyte carbohydrate antigens recognized as ligands by endothelial selectins, we assumed that they could be sens...
Article
Full-text available
Gas bubble formation during and after decompression is considered to be the main initiator of decompression sickness (DCS). Compressed-air workers have been reported to acclimatise to the working environment and hence have a reduced risk of DCS, but the exact nature of the adaptation is not known. In the present study, we investigated the effect of...
Article
Exercising before, during, or after diving is proscribed because of the assumption that it would increase incidence of decompression sickness. Our findings show that exercise performed in a timely fashion before diving or during decompression will reduce the number of venous gas bubbles formed. Exercise after diving did not increase the number of b...
Article
Full-text available
We have recently shown that a single air dive leads to acute arterial vasodilation and impairment of endothelium-dependent vasodilatation in humans. Additionally we have found that predive antioxidants at the upper recommended daily allowance partially prevented some of the negative effects of the dive. In this study we prospectively evaluated the...
Article
We report a case of right-to-left intrapulmonary (IP) shunting of venous gas bubbles at a high level of exercise after diving. The diagnosis was made using a 4-chamber view of the heart via echocardiography during exercise. This case is the first in which we could find evidence of IP shunt recruitment during exercise after diving, and the bubble gr...
Article
Full-text available
There is a relationship between gas bubble formation in the vascular system and serious decompression sickness. Hence, control of the formation of vascular bubbles should allow safer decompression procedures. There were 12 pigs that were randomly divided into an experimental group (EXP) and a control group (CTR) of 6 animals each. The pigs were com...
Article
The presence of gas bubbles in the vascular system is often considered a sign of decompression stress and several studies in the existing literature have addressed the relationship between the amount of bubbles detected by ultrasound Doppler systems and the incidence of decompression sickness. The use of ultrasound imaging has some important advant...
Article
Verification of new decompression procedures has traditionally been based on observing the occurrence of decompression sickness (DCS) in test dives. Several hundred exposures are required to determine the safety of a procedure with any degree of certainty. The number of venous gas emboli (VGE) corresponds with the risk of getting DCS and detection...
Article
Diving-induced acute alterations in cardiovascular function such as arterial endothelial dysfunction, increased pulmonary artery pressure (PAP) and reduced heart function have been recently reported. We tested the effects of acute antioxidants on arterial endothelial function, PAP and heart function before and after a field dive. Vitamins C (2 g) a...
Chapter
Diving, as a method for exploring and exploiting the underwater world, requires equipment and methods that have been available for only about 200 years. The first practical procedures for decompression from dives were developed by Boycott and colleagues (1) at the beginning of the 1900s. With the development of the self-contained underwater breathi...
Article
Today's human body was “designed,” through natural selection, to maximize fitness in the early ancestral environment, a time in which physical activity was obligatory for survival (see Chapter 16).As an important corollary, the human body is not ideally suited for the modernWestern lifestyle, where inactivity is the norm. Indeed, physical inactivit...
Article
Full-text available
It has previously been reported that a nitric oxide (NO) donor reduces bubble formation from an air dive and that blocking NO production increases bubble formation. The present study was initiated to see whether a short-acting NO donor (glycerol trinitrate, 5 mg/ml; Nycomed Pharma) given immediately before start of decompression would affect the am...
Article
Recent studies have shown that a nitric oxide releasing agent or a single bout of high-intensity exercise 20-24 h before a dive can prevent bubble formation following decompression. The aim of this study was to determine whether high-intensity exercise immediately prior to a dive eliminates the protective effect of a single bout of high-intensity e...
Article
Prevention of bubble formation is a central goal in standard decompression procedures. Previously we have shown that exercise 20-24 h prior to a dive reduces bubble formation and increases survival in rats exposed to a simulated dive. Furthermore, we have demonstrated that nitric oxide (NO) may be involved in this protection; blocking the productio...
Article
Regular exercise training has emerged as a powerful tool to improve endothelium-dependent vasorelaxation. However, little is known about the magnitude of change and the permanence of exercise-induced adaptations in endothelial function. Rats were randomized to either 6 weeks of regular exercise or one bout of exercise. Rats were then sacrificed 0,...
Article
After decompression from dives, bubbles are frequently observed in the right ventricular outflow tract and may lead to vascular damage, pulmonary arterial hypertension and right ventricular overload. No data exist on the effect of open sea diving on the pulmonary artery pressure (PAP). Eight professional divers performed an open sea air dive to 30...
Article
Full-text available
The rate of nitrogen elimination may be an important factor in evaluating the risk of DCS following dives. The present study determined the reproducibility of a method for evaluating nitrogen elimination (series I), and the effect of chronic training on the nitrogen elimination in healthy young women (series II). Nitrogen elimination was determined...
Article
Venous gas emboli are frequently observed in divers even if proper decompression procedures are followed. This study was initiated to determine if pulmonary artery pressure increases in asymptomatic divers, which could increase the risk of arterial embolization due to passage of venous gas emboli from the right to the left side of the heart. Record...
Article
Full-text available
The use of photodynamic therapy (PDT) to treat malignant tumors involves a photosensitizing drug, light, and oxygen. Since PDT requires oxygen, the purpose of this study was to investigate whether increased oxygen tension increases cell death compared with normoxic conditions (21 kPa oxygen). The effect of hyperoxia on PDT and lipid peroxidation wa...
Article
Full-text available
Paradoxical arterializations of venous gas emboli can lead to neurological damage after diving with compressed air. Recently, significant exercise-induced intrapulmonary anatomical shunts have been reported in healthy humans that result in widening of alveolar-to-arterial oxygen gradient. The aim of this study was to examine whether intrapulmonary...
Article
Paradoxical arterializations of venous gas emboli can lead to neurological damage after diving with compressed air. Recently, significant exercise-induced intrapulmonary anatomical shunts have been reported in healthy humans that result in widening of alveolar-to-arterial oxygen gradient. The aim of this study was to examine whether intrapulmonary...
Article
During and after decompression from dives, gas bubbles are regularly observed in the right ventricular outflow tract. A number of studies have documented that these bubbles can lead to endothelial dysfunction in the pulmonary artery but no data exist on the effect of diving on arterial endothelial function. The present study investigated if diving...