Decompression procedures for transfer under pressure ('TUP') diving.

Background: There is an increasing interest in 'transfer under pressure' (TUP) decompression in commercial diving, bridging traditional surface-oriented diving and saturation diving. In TUP diving the diver is surfaced in a closed bell and transferred isobarically to a pressure chamber for final decompression to surface pressure.

Methods: Tables for air diving and air and oxygen decompression have been compared for total decompression time (TDT), oxygen breathing time as well as high and low gradient factors (GF high and low).

The Assessment of Daily Energy Expenditure of Commercial Saturation Divers Using Doubly Labelled Water.

Commercial saturation divers are exposed to unique environmental conditions and are required to conduct work activity underwater. Consequently, divers' physiological status is shown to be perturbed and therefore, appropriate strategies and guidance are required to manage the stress and adaptive response. This study aimed to evaluate the daily energy expenditure (DEE) of commercial saturation divers during a 21-day diving operation in the North Sea.

The relationship between venous gas bubbles and adverse effects of decompression after air dives.

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 advantages to Doppler systems, and here we have looked at the relationship between the amount of intravascular gas bubbles detected by ultrasound echocardiography and the incidence of signs and symptoms of decompression stress after 203 air dives. The results show that venous gas bubbles detected by ultrasound imaging is a highly sensitive, although not specific, predictor of such adverse effects of decompression.

Validation of decompression procedures based on detection of venous gas bubbles: A Bayesian approach.

Introduction: 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 of VGE has been used as an alternative method for validation of decompression procedures.

Venous gas embolism in chamber attendants after hyperbaric exposure.

An initial occupational survey (OS) was initiated to investigate the prevalence of venous gas embolism (VGE) in chamber attendants assisting hyperbaric oxygen (HBO2) treatments. Nine female subjects were exposed for three consecutive days to the routine hospital procedure of compressed air exposure to 240 kPa for approximately 115 min with 12 min of terminal oxygen (O2) breathing. VGE was monitored with ultrasound Doppler in 15 min intervals for 2h after the first and third exposure.

A randomized, double blind study of the prophylactic effect of hyperbaric oxygen therapy on migraine.

In a double blind, placebo-controlled study to assess the prophylactic effect of hyperbaric oxygen therapy on migraine, 40 patients were randomly assigned to a treatment group receiving three sessions of hyperbaric oxygen, or a control group receiving three hyperbaric air treatments. The patients were instructed to keep a standardized migraine diary for eight weeks before and after the treatment. Thirty-four patients completed the study.

Comparison of three different ultrasonic methods for quantification of intravascular gas bubbles.

For evaluating different decompression schedules, the use of ultrasound is common. Systems based on the Doppler principle have mostly been used. However, ultrasonic scanners producing images where the bubbles are easily detected, may be an alternative, because analysis of the signals is simpler than when using Doppler methods.

Agreement between trained and untrained observers in grading intravascular bubble signals in ultrasonic images.

In our experience, it is easier to identify gas bubbles in ultrasonic images than in aural Doppler signals. To verify this, we asked 27 observers with no previous training to estimate the quantity of gas bubbles in video tapes containing sequences of ultrasound images recorded during decompression experiments. The amount of bubbles was graded according to a non-linear grading system with six levels.

Relationship between venous bubbles and hemodynamic responses after decompression in pigs.

We present a new pig model for studying relationships between venous gas bubbles and physiologic effects during and after decompression. Sixteen pigs were anesthetized to allow spontaneous breathing. Eight of them underwent a 30-min exposure to 5 bar (500 kPa) followed by a rapid decompression to 1 bar (2 bar/min); the remaining eight served as controls.