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Reprinted
with permission from DAN
1991 Undersea and Hyperbaric Medical Society
Annual Scientific Meeting Abstract Form
ULTRASONIC DOPPLER
MEASUREMENT OF SPORT DIVERS AT ALTITUDE. C.J. Wachholz, R. Dunford,
P.B. Bennett, Divers Alert Network (DAN), Box 3823, Duke University
Medical Center, Durham, NC
 The
Divers
Alert Network (DAN) has since 1985 used ultrasonic Doppler to
measure sport divers making unsupervised dives in open water. Most
of these measurements have taken place in warm tropical ocean waters at
sea level. In 1990, two groups of sport divers were measured at
altitude following sport diving. The first group of 15 divers were
measured while diving off the Caribbean Island of Saba Netherlands
Antilles. Measurements fo 12 subjects were conducted both at sea
level and at an elevation of 1200 feet, the altitude of the divers'
hotel. Excursions to 1200 feet occurred each day following the
last dive of the day, between 40-80 minutes after exiting the water from
the last dive. Divers made three dives per day on most days.
One Doppler measurement was taken between 30-40 minutes following each
repetitive dive. Divers were measured immediately prior and
immediately following the excursion to 1200 feet. Of the 15
divers, 10 (75%) had positive bubble scores, all grade one or two (Kisman
Masurel Scale). There was no increase in bubble scores following
the excursions to altitude for any of the subjects. Because of
Saba's close proximity to St. Maarten, tourists regularly fly over to
dive for the day. For over ten years, following scuba dives,
return flights to St. Maarten have occurred at altitudes of 1500-4000
feet. No cases of DCS as a result of these flights have been
reported to Divers Alert Network. This information is important in
light of the recently issued minimum 12-hour Flying-After-Diving
recommendations (Sheffield, et al., UHMS, Publ. no. 77, 12/89).
Dive resort operations in the Caribbean that relied on one to three day
dive package business have complained that the 12-hour guideline is too
conservative. Another group that has taken issue with the
necessity of a 12-hour delay to altitude are the freshwater divers of
the Rocky Mountain region. A second group of 12 Doppler subjects
from Grand Junction, Colorado, elevation 4,843 ft, were measured
following single day diving at Lake Powell, UT, elevation 3736
feet. In this group, 7 of the divers (58%) had bubbles, all grade
one or two, except one individual who had a grade three bubble
score. Both the Saba and Utah dives were repetitive, with the
deepest dive first in all cases. In both groups, the effect of
depth (dive #1) produced more bubbles than subsequent repetitive dives
or from any altitude effect. As the '89 Flying-After-Diving
workshop guidelines were only concerned with excursions on commercial
aircraft assuming an 8000 foot cabin altitude, alternate recommendations
for altitude excursions following sport dives to lower altitudes should
be considered
This page last updated on
11/22/2007
from our Windwardside office.
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