James R. Holm

Prospective assessment of outcomes in 411 patients treated with hyperbaric oxygen for chronic radiation tissue injury

Although hyperbaric oxygen is used to treat chronic radiation tissue injury, clinical evidence supporting its efficacy has been limited to date. The authors report prospectively collected patient outcomes from a single centers large experience using hyperbaric oxygen to treat chronic radiation injury.

Altitude exposures during commercial flight: a reappraisal.

BACKGROUND Hypobaric hypoxia during commercial air travel has the potential to cause or worsen hypoxemia in individuals with pre-existing cardiopulmonary compromise. Knowledge of cabin altitude pressures aboard contemporary flights is essential to counseling patients accurately about flying safety. The objective of the study was to measure peak cabin altitudes during U.S. domestic commercial flights on a variety of aircraft. METHODS A handheld mountaineering altimeter was carried by the investigators in the plane cabin during commercial air travel and peak cabin altitude measured. The values were then compared between aircraft models, aircraft classes, and distances flown. RESULTS The average peak cabin altitude on 207 flights aboard 17 different aircraft was 6341 +/- 1813 ft (1933 m +/- 553 m), significantly higher than when measured in a similar fashion in 1988. Peak cabin altitude was significantly higher for flights longer than 750 mi (7085 +/- 801 ft) compared to shorter flights (5160 +/- 2290 ft/1573 +/- 698 m). Cabin altitude increased linearly with flight distance for flights up to 750 mi in length, but was independent of flight distance for flights exceeding 750 mi. Peak cabin altitude was less than 5000 ft (1524 m) in 70% of flights shorter than 500 mi. Peak cabin altitudes greater than 8000 ft (2438 m) were measured on approximately 10% of the total flights. CONCLUSIONS Peak cabin altitude on commercial aircraft flights has risen over time. Cabin altitude is lower with flights of shorter distance. Physicians should take these factors into account when determining an individuals need for supplemental oxygen during commercial air travel.

Diffusion of Carbon Monoxide Through Gypsum Wallboard

Diffusion of Carbon Monoxide Through Gypsum Wallboard Carbon monoxide (CO) poisoning is a significant US health problem, responsible for approximately 500 accidental deaths annually,1 and a risk of 18% to 35% for cognitive brain injury 1 year after poisoning.2 Most morbidity and mortality from CO poisoning is believed to be preventable through public education and CO alarm use. States have been enacting legislation mandating residential CO alarm installation.3 However, as of December 2012, 10 of the 25 states with statutes mandating CO alarms exempted homes without fuel-burning appliances or attached garages, believing that without an internal CO source, risk is eliminated. This may not be true if CO diffuses directly through wallboard material.

SHOULD THE PLACEMENT OF CARBON MONOXIDE (CO) DETECTORS BE INFLUENCED BY CO'S WEIGHT RELATIVE TO AIR?

BACKGROUND Numerous states and localities have recently passed legislation mandating the installation and use of residential carbon monoxide (CO) detectors/alarms. Interestingly, there seems to be confusion about the optimal placement, if any, of CO alarms inside the home. OBJECTIVES It was the goal of this study to demonstrate the behavior of CO in air and to help provide a data-based recommendation for CO alarm placement. METHODS CO was calculated to be slightly lighter than air. An 8-foot-tall airtight Plexiglas chamber was constructed and CO monitors placed within at the top, middle, and bottom. CO test gas (15 L, 3000 parts per million) was infused at each of the three heights in different trials and CO levels measured over time. RESULTS Contrary to a significant amount of public opinion, CO did not layer on the floor, float at the middle of the chamber, or rise to the top. In each case, the levels of CO equalized throughout the test chamber. It took longer to equalize when CO was infused at the top of the chamber than the bottom, but levels always became identical with time. CONCLUSIONS As would have been predicted by the Second Law of Thermodynamics, CO infused anywhere within the chamber diffused until it was of equal concentration throughout. Mixing would be even faster in the home environment, with drafts due to motion or temperature. It would be reasonable to place a residential CO alarm at any height within the room.

The Role of Hyperbaric Oxygen as Salvage Therapy for Sudden Sensorineural Hearing Loss

Objective: We sought to evaluate hearing outcomes after salvage therapy with hyperbaric oxygen (HBO2) for the treatment of sudden sensorineural hearing loss (SSNHL). Study Design: Matched control retrospective case series. Setting: Tertiary neurotology referral center. Patients: Thirty-six patients (>18 years) diagnosed with SSNHL. Intervention: Patients received initial therapy with oral and/or intratympanic (IT) steroids with an incomplete response. Eighteen patients underwent salvage therapy with IT steroids and HBO2 (group 1). Eighteen matched controls underwent salvage therapy with IT steroids alone (group 2). Main outcome measures: The main outcome measure was improvement in pure tone average (PTA) and word recognition score (WRS). Complications as a result of therapy were also monitored. Results: There were no significant differences in age, gender, or hearing between the 2 groups (P > .05). There was no significant difference in mean post-treatment PTA between group 1 (60.3 dB) and group 2 (53.2 dB). There were no significant difference in mean post-treatment WRS between group 1 (42%) and group 2 (51%). Serviceable hearing was defined as a minimum WRS of 50%. Thirty-three percent in group 1 and 42% in group 2 went from nonserviceable hearing to serviceable hearing (P > .05). PTA and WRS change scores were not significantly affected by age, gender, form of initial treatment, or pre-treatment PTA and WRS. Conclusion: The present study demonstrated no significant difference in hearing outcomes between patients receiving salvage therapy with HBO2 and IT steroids compared to patients receiving IT steroids alone. Larger, prospective randomized trials are needed to better define the role of HBO2 as salvage therapy for SSNHL.

Imaging in situ human kidney stones with the color Doppler ultrasound twinkling artifact

Hyperbaric pressures of 3–100 atmospheres absolute (ATA) have been shown to reduce the color Doppler ultrasound twinkling artifact on ex vivo human kidney stones, leading to the hypothesis that surface crevice microbubbles cause twinkling. Similarly supportive for the crevice bubble hypothesis is the suppression of kidney stone twinkling in animals breathing elevated levels of carbon dioxide. However, it is unclear whether stable microbubbles can exist on the surface of kidney stones in the human body. For the first time, we investigate the effect of hyperbaric pressure on in situ human kidney stones to determine whether stable microbubbles exist as measured by the color Doppler ultrasound twinkling artifact.

Garage carbon monoxide levels from sources commonly used in intentional poisoning

BACKGROUND The incidence of intentional carbon monoxide (CO) poisoning is believed to have declined due to strict federal CO emissions standards for motor vehicles and the uniform application of catalytic converters (CC). We sought to compare ambient CO levels produced by automobiles with and without catalytic converters in a residential garage, as well as from other CO sources commonly used for intentional poisoning. METHODS CO levels were measured inside a freestanding 73 m3 one-car garage. CO sources included a 1971 automobile without CC, 2003 automobile with CC, charcoal grill, electrical generator, lawn mower and leaf blower. RESULTS After 20 minutes of operation, the CO level in the garage was 253 PPM for the car without a catalytic converter and 30 PPM for the car equipped withone. CO levels after operating or burning the other sources were: charcoal 200 PPM; generator >999 PPM; lawn mower 198 PPM; and leaf blower 580 PPM. CONCLUSIONS While emissions controls on automobiles have reduced intentional CO poisonings, alternate sources may produce CO at levels of the same magnitude as vehicles manufactured prior to the use of catalytic converters. Those involved in the care of potentially suicidal individuals should be aware of this.

Compliance with Washington State's requirement for residential carbon monoxide alarms

Carbon monoxide (CO) poisoning is responsible for significant morbidity and mortality in the US. In response, a majority of states have passed legislation in recent years requiring the installation of residential CO alarms. There is, however, no published information evaluating compliance with such laws. Employees of a Seattle medical center were surveyed in 2008 regarding home use of CO and smoke alarms. Washington State enacted legislation requiring residential CO alarms by all residences by January 1, 2013. The survey was repeated in mid-2016 to evaluate compliance. In 2016, a total of 354 employees completed the survey and their responses were compared to an equal number of 2008 survey respondents matched by home ownership and ZIP code. Residential CO alarm use rose from 37% to 78% (p < 0.0001). Among homeowners, 78% had alarms while 80% of renters had them. Homeowners with the highest compliance (96%) had purchased their homes since January 1, 2013 while those with the lowest compliance (73%) had purchased them earlier. A majority (79%) of renters without alarms reported the reason was that their landlord did not provide one, a violation of the law. Only one-half to two-thirds of all equipped homes had the required number of either CO or smoke alarms. Use of residential CO alarms increased significantly in this study population three years after law required them. Areas for further improvement include education of landlords, tenants, and longtime homeowners about the law, as well as public education regarding the number of CO and smoke alarms needed.

Letter re: Hyperbaric oxygen: B-Level evidence in mild traumatic brain injury clinical trials

In their article, Drs. Figueroa and Wright1 reported a reanalysis of hyperbaric oxygens effect on mild traumatic brain injury and claimed that oxygen content of arterial blood plasma (oxygen dissolved in plasma) during hyperbaric exposure correlates with treatment response.

Etiology of the color Doppler ultrasound twinkling artifact on in situ human kidney stones

Hyperbaric pressures of 0.3–10 MPa (absolute) have been shown to reduce the magnitude of the color Doppler ultrasound twinkling artifact on ex vivo human kidney stones, supporting the hypothesis that surface crevice microbubbles cause twinkling. For the first time, we investigate the etiology of twinkling on in situ human kidney stones. Eight human subjects with kidney stones known to twinkle were imaged with a Philips/ATL P4-2 transducer and Verasonics ultrasound system for 45 minutes while inside a hyperbaric chamber. Subjects breathed ambient air while the pressure in the chamber cycled to a maximum pressure of 0.4 MPa, with a scheduled decompression stop at 0.16 MPa where subjects breathed pure oxygen. Preliminary results show no change in the twinkling amplitude at 0.4 MPa compared to the baseline measurements before pressurization; however, a statistically significant increase in the twinkling amplitude was observed when subjects breathed pure oxygen at 0.16 MPa (p = 0.046). The increase in the twinkling amplitude upon changing respiratory gas composition further supports the crevice microbubble hypothesis of twinkling. Higher pressures than explored in this study may be needed to reduce twinkling on in situ human kidney stones. [Work supported by the National Space Biomedical Research Institute through NASA NCC 9-58 and NIH grant DK043881.]Hyperbaric pressures of 0.3–10 MPa (absolute) have been shown to reduce the magnitude of the color Doppler ultrasound twinkling artifact on ex vivo human kidney stones, supporting the hypothesis that surface crevice microbubbles cause twinkling. For the first time, we investigate the etiology of twinkling on in situ human kidney stones. Eight human subjects with kidney stones known to twinkle were imaged with a Philips/ATL P4-2 transducer and Verasonics ultrasound system for 45 minutes while inside a hyperbaric chamber. Subjects breathed ambient air while the pressure in the chamber cycled to a maximum pressure of 0.4 MPa, with a scheduled decompression stop at 0.16 MPa where subjects breathed pure oxygen. Preliminary results show no change in the twinkling amplitude at 0.4 MPa compared to the baseline measurements before pressurization; however, a statistically significant increase in the twinkling amplitude was observed when subjects breathed pure oxygen at 0.16 MPa (p = 0.046). The increase in the twin...