Case 4 (female)
The member exhaled before placing the mask in the working position and
after 30 s she appeared conscious. At 33 s she nodded 'yes' to an
attendant's query whether she was breathing. Immediately afterwards
the member's eyelids blinked rapidly. It is estimated that
consciousness was lost 55 s after the mask was put in place. At 1:11
her eyeballs rolled and there were tremors in both hands. The tremors
continued to 2:06 and then the body appeared relaxed. At 2:09 the
breathing rate quickened for approximately 6 s. At 3:03 there was a
slow extension and contraction of both arms, which then relaxed at the
member's sides at 3:26.
At 3:58 breathing began to accelerate, pausing occasionally, and then
accelerating again. From 5:36 to 10:12 there was intermittent moaning.
During this same period the eyelids were open and the eyeballs were
moving, but without appearance of control. Between 10:13 and 38:16,
intermittent patterns of accelerated breathing, relaxed breathing and
moaning continued. During this period a number of movements occurred:
at 26:03 the head tilted back; at 30:41 the shoulders shrugged and
left arm contracted; at 34:55 the left shoulder shrugged; at 37:06
both arms contracted for 10 s after which the member appeared quite
inert.
At 38:16 the camera was turned off, to replace the video tape. The
time elapsed for this is not known. The duration of the second tape is
26:57. At 0:49 of part 2 the member let out a deep gasp and the head
tilted back to 0:57. At 1:31 the tongue extended slightly and
withdrew. This tongue movement continued at 15–20 s intervals until
3:45, after which no further signs of life were apparent. The camera
continued to run from 3:45 to 26:57, but the member appeared dead.
The recorded time from the start of the procedure to cessation of all
signs of life was approximately 42 minutes. The actual time from start
to finish is not known due to the change of video tape. The changes in
breathing patterns, moaning and longer dying time appeared to concern
and confuse the Dignitas attendants.
Conclusion
The estimated time to unconsciousness ranges from 36 to 55 s, which
varies greatly from 5 to 10 s noted by Clayton and Clayton.11 Precise
determination of unconsciousness onset is not possible, but it
appeared to coincide with blinking eyelids, rolling eyeballs and
increased breathing rate. In general, arm movements were limited to
uncoordinated contractions or extensions at the elbow. Neither
attendants nor members touched the mask once it was placed in the
working position. There were no attempts at self-rescue, which implies
that each member was unconscious.
While the camera was focused on the dying member, the attendants could
occasionally be observed, and they appeared anxious about the process.
One attendant later stated that the sudden change in skin colour
(cyanosis), and wide open eyelids were unexpected, because with sodium
pentobarbital the loss of consciousness is slower and the eyelids tend
to remain closed.
The time to death in cases 1–3 was approximately 5–10 minutes, and in
case 4 it was over 40 minutes. In case 4, it is probable that
sufficient oxygen was leaking into the breathing system to sustain
breathing and heart function.
Although each member followed the same breathing protocol, variances
in breathing patterns and total time to death can be attributed to
health differences, variable rebreathing, inspiratory leaks and
dilution of the inhaled mixture with room air (which would include 21%
oxygen). While health information and flow rate data are unavailable,
the video image reveals variances in the fit of the mask. Gaps noted
between face and mask would have allowed room air to enter into the
breathing environment, thereby extending the time to unconsciousness
and the time to death. Even if the Dignitas attendants were trained to
recognise a poor mask fit, they probably could not make adjustments
without running foul of the law. This is because Swiss law requires
the dying individual to perform the final act, and a third party
intervention to adjust the mask would probably constitute an offence.
We conclude that much of the variability in time to unconsciousness
and death can be attributed to differences in the mask fit. A hood
method could reduce the problems of fit. The fit at the collar must be
loose enough to serve as an exhaust port, but tight enough to ensure
that the flow of gas will maintain inflation of the hood.
Discussion
In these four cases, oxygen deprivation by breathing helium through a
mask proved lethal. Nevertheless, we believe a mask breathing
apparatus is problematical because it is very difficult to achieve and
maintain a gas-tight seal between the face and the mask. Even if the
initial mask fit is gas tight, subsequent involuntary movements of the
head, neck and facial muscles are likely to spoil the fit. In
anaesthesia, it is well known that achieving a continual airtight fit
is technically difficult. Even tiny leaks may substantially allow the
ingress of oxygen into the breathing environment. By enhancing the
video images, gaps are visible around the nose bridge and under the
chin, thus room air could easily prevent an oxygen-free environment.
Gaps of some degree may well have been present in all four cases.
The inspired concentration of air, and therefore oxygen, will be
determined by the relative amounts of added helium and expired gas. To
replace expired air completely, and thus ensure the highest possible
concentration of helium, the flow rate of added gas (helium) has been
determined to be a volume of at least two and a half times the
individual's minute volume. This would be true with either the bag and
mask as used by Dignitas, or with the use of a large hood. This flow
rate would require tubing of an adequate internal diameter to deliver
helium from the tank to the inhalation system.
'Final exit' offers detailed information about using a plastic bag
hood and helium for suicide. For aesthetic reasons, Dignitas chose a
mask instead of a hood. A hood, however, may be easier to manage than
any mask that we know. The elastic collar on a hood provides an
exhaust port.
Sudden exposure to a completely oxygen-deficient environment should
result in loss of consciousness within 5–10 s. Given the visibly poor
mask fit, and that the estimated time to unconsciousness ranged
between 36 and 55 s, it is probable that the breathing environment was
not completely oxygen deficient. In two case reports of sudden
exposure to a helium environment inside a hood, Ogden reported loss of
consciousness within 10–12 s.
Assistance with suicide is not necessarily a medical procedure and
these cases of oxygen deprivation show that the prescribing role of
physicians and the use of drugs can be bypassed. Ziegler recently
noted that the Swiss model of assisted suicide has significant
potential to inform the debate over the right to die, and that it
'could also help demedicalize the way that we die'. The transparency
of the Swiss model and the boldness of organisations such as Dignitas
provide unique opportunities to shed light upon otherwise hidden
behaviours. Switzerland is probably unique in that its right-to-die
organisations can account for nearly 5% of all suicides. Given the
nature of Swiss law and the good faith transparency and accountability
of right-to-die groups in that country, the Swiss model offers unique
opportunities for the observation and measurement of a phenomenon that
cries out for empirical enquiry and understanding.
