Repeated hyperbaric exposure and glass ampoule safety.

INTRODUCTION: It has been our institution's policy to not place glass medication ampoules inside our hyperbaric chamber for fear of rupture. There is only a small and conflicting amount of data as to whether glass ampoules are safe for use under hyperbaric conditions. OBJECTIVES: The primary objective of this study was to test the safety and usability of glass medication ampoules inside a hyperbaric chamber. METHODS: Repetitive, rapidly staged compressions and decompressions were performed on multiple different glass medications ampoules inside the medical lock of a medical hyperbaric chamber. Medication ampoules of varying sizes (1 ml to 10 ml) of medication that may be required in a hyperbaric emergency were assessed. The ampoules were rapidly compressed 100 times to pressures of 142 kPa, 183 kPa, 300 kPa, 405 kPa and 507 kPa. They were then dropped from a height of 30 cm while compressed at 507 kPa and then half the ampoules were opened while pressurized at 507 kPa. RESULTS: No ampoules were broken during compression or decompression. No ampoules broke when dropped from 30 cm onto the chamber floor. All ampoules opened at a pressure of 507 kPa functioned normally. No lids/ampoules shattered upon opening. CONCLUSION: This study suggests that glass medication ampoules appear to be safe for use inside a medical hyperbaric chamber at routine treatment pressures.

Cognitive changes after saline or plasmalyte infusion in healthy volunteers: a multiple blinded, randomized, cross-over trial.

BACKGROUND: In an incidental finding, during a study of plasma chemistry after crystalloid infusion, participants reported subjective cognitive changes, particularly slower thinking, after saline but not Hartmann's (Ringer's lactate) solution. The authors tested the hypothesis that saline infusion would produce greater adverse cognitive changes than Plasmalyte infusion. METHODS: The authors conducted a randomized, cross-over, multiple blinded study of healthy adult volunteers. On separate days, participants received 30 ml/kg over 1 h of either 0.9% saline or Plasmalyte with the order randomly allocated. Plasma chemistry was tested on venous samples. As part of a battery of cognitive tests our primary endpoint was the reaction time index after infusion. RESULTS: The authors studied 25 participants. Plasma chloride was greater after saline than after Plasmalyte: mean difference 5.4 mM (95% CI, 4.1-6.6 mM; P < 0.001). Saline was also associated with greater metabolic acidosis: base-excess 2.5 mM more negative (95% CI, 1.9-3.0 mM more negative; P < 0.001). There was no evidence of a difference in the reaction time index between the two interventions: mean reaction time index 394 ms (SD, 72) after saline versus 385 ms (SD, 55) after Plasmalyte. Difference: saline 9 ms slower (95% CI, 30 ms slower to 12 ms faster; P = 0.39). There were minimal differences in the other cognitive and mood tests. CONCLUSIONS: Despite expected differences in plasma chemistry, the authors found that measures of cognition did not differ after infusions of Plasmalyte or saline.