Hyperbaric chamber attendant safety I: Doppler analysis of decompression stress in multiplace chamber attendants.

INTRODUCTION

Incidences of decompression sickness of 0.76% have been reported in hyperbaric attendants exposed to routine 243 kPa treatment tables. Occupational health risks of this magnitude are not acceptable in routine clinical practice. Significant variations in procedures are therefore found between institutions in an attempt to enhance staff safety. In extreme cases, the use of multiplace chambers has been abandoned. Doppler ultrasound provides an objective tool to assess the sub-clinical decompression stress associated with any particular exposure.

AIMS

To assess the decompression stress imposed upon staff exposed to our routine 243 kPa table and to elucidate demographic details within the attendant population that impact upon that stress.

DESIGN

prospective observational cohort study. Profile: 243 kPa for 90 min with a 20 min decompression on oxygen.

SUBJECTS

28 nursing and medical personnel routinely undertaking patient care under hyperbaric conditions.

PROCEDURE

Doppler assessment at 20 min intervals for up to 120 min post-exposure. Scoring: aural grading of intravascular bubbles using the Kisman-Masurel (K-M) scoring system; 163 exposures were scrutinized in this manner.

RESULTS

68% of exposures resulted in 'low' (K-M Grades 0-I), 22% in 'intermediate' (Grade II) and 10% in 'high' sub-clinical decompression stress (Grades III-IV). Female gender and increasing age, weight and exposure frequency showed trends towards higher bubble grades. There were no cases of clinical decompression sickness.

CONCLUSIONS

Our standard 243 kPa table conforms to DCIEM definitions of 'acceptable' decompression stress (Grade II or fewer bubbles in ≥50% of the subjects). Significant inter- and intra-individual variability was evident even within this one, tightly controlled dive profile.