Hypoxemia with air breathing periods in U.S. NAVY Treatment Table 6.

Air breathing is used to lessen hyperbaric oxygen (HBO2) toxicity. Hypoxemia could occur during hyperbaric air breathing in patients with lung dysfunction, although this has not been previously reported. We report two cases of hypoxemia during air breathing with two patients treated with the US Navy Table 6. Patient 1 was an 11-year-old male with cerebral gas embolism (during cardiac transplantation), patient 2 was a 66-year-old female with cerebral gas embolism from a central venous catheter accident. Both were mechanically ventilated. We monitored arterial blood gas (ABG) during therapy. In both patients, ABG measurements showed hypoxia during the first air breathing period at 1.9 atm abs (192.5 kPa). If patients require > or = 40% inspired oxygen before HBO2 therapy, oxygenation monitoring is advisable during air breathing periods, especially at lower chamber pressures (< or = 2.0 atm abs).

Energy, water balance and the roost microenvironment in three Australian cave-dwelling bats (Microchiroptera).

The ghost bat, Macroderma gigas, and the orange leaf-nosed bat, Rhinonycteris aurantius, occupy similar ranges across northern Australia and are often found in the same roost caves. Both species are considered rare and vulnerable to further population decline. A third small species, the large bent-wing bat, Miniopterus schreibersii, has a similar body mass to R. aurantius, but has one of the largest ranges of any Australian mammal. In the present study we examine the effect and sensitivity of the animals' roosting microclimates on their energy and water balance. M. schreibersii exhibits a basal metabolic rate about 40% greater than other bats of similar body mass, whereas the other two species are close to predicted levels. R. aurantius shows a decrease in body temperatures below thermoneutrality. R. aurantius has levels of pulmocutaneous water loss among the highest seen for a mammal, and calculations based on nasal tip temperatures suggest that most of this loss is across the skin. Calculated ambient temperatures at which metabolic water production is equal to pulmocutaneous water loss in dry air are -14.7 degrees C for R. aurantius, 9.8 degrees C for M. schreibersii and -0.3 degrees C for M. gigas. Exposing the animals to relative humidities of between 80% and 90% shifted these calculated temperatures to 5.6 degrees C, 25.2 degrees C, and 2.9 degrees C, respectively. For each species the ratio of metabolic water production to evaporative water loss has been treated as a joint function of humidity and ambient temperature. The resulting surface plot shows that under known roosting conditions in caves R. aurantius and M. schreibersii remain in positive water balance, whereas M. gigas does not.