Wireless point-of-care ultrasound in a multiplace hyperbaric chamber.

Background: Electronic devices remain highly restricted from use during hyperbaric oxygen (HBO2) treatment due to risk of fire in a pressurized, oxygen-rich environment. Over recent decades, point-of- care ultrasound (POCUS) has established utility in most clinical environments except hyperbaric chambers, where only heavily modified POCUS devices have been used. This study evaluated proof of concept, safety, and performance of a wireless off-the-shelf handheld POCUS device in the hyperbaric environment. Materials and Methods: The GE Vscan Air was initially tested in a Class C chamber with 100% nitrogen up to 4.0 ATA and monitored. Second, the Vscan Air was paired with an encased Apple iPad, tested previously for hyperbaric use, and both were pressurized to 2.4 ATA in a Class A chamber (21% oxygen) and evaluated. Similarly, it was then tested at 2.8 ATA and also paired wirelessly with an iPad outside the chamber. Device temperature, image quality, functionality, and wireless connection were tested continuously. Results: The GE Vscan Air automatically shut off due to power button depression during initial compression; thus the power button was punctured with an 18-gauge needle to equalize gas pressure. Thereafter, the system performed well throughout all tests without degradation in function or image quality. The device did not overheat nor reach temperatures concerning for fire hazard. Further, wireless connection to out-of-chamber devices was maintained. Conclusions: Our results suggest that the GE Vscan Air can be used with minor modification in a multi- place hyperbaric chamber. Wireless functionality allows for pairing with a screen and device outside the chamber.

Performance of the Uni-Vent Eagle™ Model 754 ventilator under hyperbaric conditions.

Critically ill patients needing mechanical ventilation may require hyperbaric oxygen therapy. Some institutions still use ventilators that were available prior to the advent of hyperbaric-specific units, such as the Uni-Vent Eagle™ Model model 754. Here we examine the performance of the Uni-Vent model 754 under hyperbaric conditions and investigate concerns of an oxygen leak in the ventilator housing, which poses a fire risk. We studied the ventilator at 1.0, 2.4 and 2.8 ATA in assist control mode using a Michigan test lung and a variety of tidal volumes and respiratory rates. We recorded the delivered volumes, peak pressures, and oxygen percentages within the hyperbaric chamber at 2.4 and 2.8 ATA and within the ventilator housing. At those pressures the ventilator delivered approximately 25% less volume than at 1.0 ATA. We observed breath stacking at high respiratory rates, but this was blunted at both 2.4 and 2.8 ATA. Oxygen levels did not rise in the housing during our investigation. In addition, we fit a linear regression to the data comparing set tidal volumes and delivered tidal volumes in order to model the changes observed. Hyperbaric conditions caused decreased delivered tidal volumes in a depth-dependent fashion, and oxygen levels within the housing did not rise. The Uni-Vent Eagle model 754 performed safely and effectively at depth but requires spirometry to correctly program desired ventilator settings.

Point-of-care ultrasound in a multiplace hyperbaric chamber.

Historically, electronic devices have been generally prohibited during hyperbaric oxygen (HBO2) therapy due to risk of fire in a pressurized, oxygen-rich environment. Point-of-care ultrasound (POCUS) however has emerged as a useful imaging modality in diverse clinical settings. Hyperbaric chambers treating critically ill patients would benefit from the application of POCUS at pressure to make real-time patient assessments. Thus far, POCUS during HBO2 therapy has been limited due to required equipment modifications to meet safety standards. Here we demonstrate proof of concept, safety, and successful performance of an off-the-shelf handheld POCUS system (SonoSite iViz) in a clinical hyperbaric environment without need for modification.

Hyperbaric medicine simulation education curriculum: CNS toxicity during Treatment Table 6 and intubated ICU patient with mucous plugging.

INTRODUCTION/BACKGROUND: The incidence of complications and number of critically ill patients in hyperbaric medicine is relatively low [1]. This poses a challenge to those tasked with educating trainees as well as maintaining the skills of staff. Hyperbaric medicine fellows may not be exposed to critical patient scenarios or complications of hyperbaric medicine during a one-year fellowship. Additional staff may be unfamiliar with these situations as well. The purpose of hyperbaric simulation curriculum is to train health care providers for rare situations. To our knowledge, this hyperbaric simulation curriculum is the first published use of simulation education in the specialty of undersea and hyperbaric medicine. MATERIALS AND METHODS: Two simulation cases have been developed that involve a patient with oxygen toxicity during hyperbaric treatment as well as an ICU patient with mucous plugging. RESULTS: Medical training simulations are an effective method of teaching content and training multiple roles in Undersea and Hyperbaric Medicine. SUMMARY/CONCLUSIONS: A hyperbaric simulation curriculum is an achievable educational initiative that is able to train multiple team members simultaneously in situations that they may not encounter on a regular basis. We believe that this could be easily exported to otherinstitutions for further education.

Incidence of DCS and oxygen toxicity in chamber attendants: a 28-year experience.

Decompression sickness (DCS) and central nervous system oxygen toxicity are inherent risks for "inside" attendants (IAs) of hyperbaric chambers. At the Hyperbaric Medicine Center at the University of California San Diego (UCSD), protocols have been developed for decompressing IAs. Protocol 1: For a total bottom time (TBT) of less than 80 minutes at 2.4 atmospheres absolute (atm abs) or shallower, the U.S. Navy (1955) no-decompression tables were utilized. Protocol 2: For a TBT between 80 and 119 minutes IAs breathed oxygen for 15 minutes prior to initiation of ascent. Protocol 3: For a TBT between 120-139 minutes IAs breathed oxygen for 30 minutes prior to ascent. These protocols have been utilized for approximately 28 years and have produced zero cases of DCS and central nervous system oxygen toxicity. These results, based upon more than 24,000 exposures, have an upper limit of risk of DCS and oxygen toxicity of 0.02806 (95% CI) using UCSD IA decompression Protocol 1, 0.00021 for Protocol 2, and 0.00549 for Protocol 3. We conclude that the utilization of this methodology may be useful at other sea-level multiplace chambers.

Single Versus Multiple Hyperbaric Sessions for Carbon Monoxide Poisoning in a Murine Model.

Hyperbaric oxygen (HBO) has been advocated for treatment of acute carbon monoxide (CO) poisoning. There exists considerable debate as to whether HBO prevents delayed neurologic sequelae (DNS) due to CO poisoning. Additionally, existing data in the literature supporting HBO efficacy do not identify an optimal number of HBO treatments. We sought to determine in a mouse model whether there is a difference between one versus multiple HBO sessions for the prevention of DNS. Fifty mice were randomized into five groups of ten mice each: (1) control, receiving no CO exposure or treatment; (2) CO poisoned, receiving no treatment (CO group); (3) CO poisoned, receiving normobaric oxygen for 58 min following the end of exposure (CO + NBO group); (4) CO poisoned, followed by one session of HBO(CO + HBO1); and (5) CO poisoned, followed by three HBO treatment sessions, one every 6 h (CO + HBO3). Prior to poisoning, all animals were trained in step-down latency (SDL) and step-up latency (SUL) tasks. One week after exposure and treatment, all five groups were retested to evaluate the retention of this training. There was no difference detected among groups in SDL (p = 0.67 among all groups) when evaluated using a Kruskal-Wallis test. There was a significant difference among groups in SUL (p = 0.027 among all groups) when evaluated using a Kruskal-Wallis test. When individual groups were compared using a Wilcoxon signed-rank test with Bonferroni correction, there were no statistically significant differences in either SDL or SUL. There was no difference between groups treated with either one or three HBO sessions. One possibility to explain this might be that HBO sessions administered some time after a CO exposure may enhance the lipid peroxidation cascade and worsen neurologic outcomes; alternatively, HBO may simply impart no benefit when compared to NBO.